JP2002311382A - Illumination optical device and projection display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive and compact illumination optical device capable of efficiently converting white light from a light source into polarized light and uniformly illuminating an image forming means, and a projection display device using the same. . SOLUTION: A lamp 30, an ellipsoidal mirror 31, a wire grid polarization separation element 32 arranged at a position where light converges, a reflection mirror 33, an aspheric lens 34,
Lens array plate 35 and second lens array plate 36
And 1/2 arranged near the second lens array plate 36
The illumination optical device is constituted by the wave plate 37 and the liquid crystal panel 4.
Light 1

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illumination optical device for illuminating light from a light source on an image forming means. In addition, the present invention relates to a projection display device that irradiates an image formed on an image forming unit with illumination light and enlarges and projects the image on a screen by a projection lens.

[0002]

2. Description of the Related Art An optical image corresponding to a video signal is formed on a small-sized image forming means, which is illuminated with light from a light source, and the optical image is projected on a screen via a projection lens, enlarged and enlarged. 2. Description of the Related Art A projection display device for obtaining an image on a screen is used.
As an image forming unit, a liquid crystal panel of an active matrix type, which modulates light using polarized light, is widely used. An illumination optical device that illuminates a liquid crystal panel with light from a light source uses two lens array plates including a plurality of lenses. The light beam incident on one lens array plate arranged on the light source side is divided into many light beams, and each of the split light beams is superimposed on the liquid crystal panel via the other lens array plate, so that the liquid crystal panel is efficiently and uniformly formed. Can be illuminated. Also, as an illumination optical device of a projection type display device using a liquid crystal panel using polarized light, natural light is polarized by using a polarized light separating prism array as a polarized light separating means and a half-wave plate as a polarized light rotating means. 2. Description of the Related Art There is known an illumination optical device that configures a polarization conversion element that converts light into one direction so as to improve the light use efficiency of a projection display device and increase the brightness of the projection display device (for example, an illumination optical device). And JP-A-8-304739).

FIG. 12 shows a projection display device in which a conventional illumination optical device 10 is introduced. Radiation light from the discharge lamp 1 as a light source is condensed by the parabolic mirror 2 and converted into a substantially parallel light beam. The parallel luminous flux enters the first lens array plate 3 and the second lens array plate 4 in order.
The first lens array plate 3 is composed of a plurality of rectangular lens elements, and the second lens array plate 4 is composed of a plurality of rectangular lens elements respectively corresponding to the plurality of lens elements of the first lens array plate 3. . The first lens array plate 3
Each lens element divides the incident light beam into a large number, and converges each light beam on each lens element of the second lens array plate 4. Many minute light source images are formed on each lens element of the second lens array plate 4.

The light emitted from the second lens array plate 4 is
The light enters the polarization conversion optical element 7. The polarization conversion optical element 7 is composed of a polarization separation prism array 5 and a 回 転
And a wave plate 6. The polarized light separating prism array 5 is a prism array in which columnar prisms having a substantially parallelogram cross section are joined alternately through polarized light separating films and reflective films. The polarization separation prism array 5 converts the natural light emitted from each lens element of the second lens array plate 4 into light beams having polarization directions orthogonal to each other.
Into two polarized lights. One of the separated polarized lights passes through the half-wave plate 6 when the polarized light is emitted from the polarized light separating prism array 5, and the polarization direction is rotated.
The light is emitted from the polarization separation prism array 5 without passing through the wave plate 6. In this way, the polarization conversion element 7 converts the incident natural light into polarized light whose polarization direction is aligned in one direction and emits it.

After passing through the condenser lens 8, the emitted light is reflected by the reflection mirror 9, and separated into three primary colors of green, red and blue by dichroic mirrors 11 and 12 constituting a color separation optical system 13. . The green light is reflected by the dichroic mirror 12 and enters the liquid crystal panel 22, and the red light is reflected by the reflection mirrors 15 and 16 and then enters the liquid crystal panel 24.
After the blue light is reflected by the reflection mirror 14, the liquid crystal panel 23
Incident on. The second lens array plate 4 and the condensing lens 8 connect each lens element of the first lens array plate 3 to the liquid crystal panel 2.
Superimposed images are formed on 2, 23 and 24. A large number of luminous fluxes divided by the first lens array 3 are
The liquid crystal panel 2 is superimposed on 2, 23 and 24.
2, 23, 24 uniform illumination is performed. Relay lens 1
Reference numerals 7 and 18 denote the second lens array plate 4 and each liquid crystal panel 2.
The difference in the intensity of the illumination light to each of the liquid crystal panels 22, 23, and 24 due to the difference in the illumination light path length, which is the distance to 2, 23, and 24, depending on the color light is corrected. The field lenses 19, 20, and 21 are provided with liquid crystal panels 22, 2 respectively.
Illumination light to 3 and 24 is focused on the pupil plane of the projection lens 28.

The three primary colors of green, red and blue emitted from the liquid crystal panels 22, 23 and 24 are synthesized by a dichroic prism 27 formed by intersecting a blue reflecting dichroic mirror 25 and a red reflecting dichroic mirror 26. After that, the light enters the projection lens 28. The projection lens 28 enlarges and projects the images of the liquid crystal panels 22, 23, and 24 on a screen (not shown).

As a polarization separating means for separating natural light into two polarized lights whose polarization directions are orthogonal to each other, a polarization separation prism for performing polarization separation by a thin film utilizing a Brewster angle is widely used. 2. Description of the Related Art A wire grid polarization separation element that performs polarization separation by using a metal grid in which a metal is formed in a fine lattice shape is known (for example, U.S. Pat.
S. P. 6, 108, 131).

As described above, the illumination optical device and the projection display device constituted by using the two lens array plates and the polarization splitting prism array make it possible to obtain a bright, uniform luminance large-screen image. Have been.

[0009]

The polarization separating prism array 5 used in the conventional projection display device shown in FIG.
After alternately bonding a parallel plate glass having a polarization separation film on one surface and a reflection film on the other surface and a parallel plate glass not having these films alternately with an adhesive, the glass It is manufactured by cutting at 45 degrees to the surface. Further, a half-wave plate 6 made of a stretched film is attached to a portion of one of the cut surfaces where the polarization direction is rotated, thereby constituting a polarization conversion element 7. The polarization separation prism array 5 having such a configuration is very expensive, and an inexpensive polarization conversion optical system is desired.

On the other hand, the arrangement pitch of the columnar prisms of the polarization splitting prism array 5 is configured to be about の of the pitch of the rectangular lens elements of the second lens array plate 4. If the arrangement pitch of the prisms of the polarization splitting prism array 5 deviates from the lens element pitch of the second lens array plate 4, the light use efficiency of the illumination optical device decreases. Therefore, when the number of divisions (number of lens elements) of the first and second lens array plates 3 and 4 is fixed and the first and second lens array plates 3 and 4 are miniaturized in order to reduce the size of the apparatus, polarization The pitch of the separation prism array 5 also needs to be precisely narrowed correspondingly. However, the arrangement pitch accuracy of the polarization separation prism array obtained by bonding and cutting by the above-described method cannot be said to be high, and there is a problem that the light use efficiency is reduced when the pitch is narrowed.

Also, the disclosed polarization conversion optical device using the wire grid polarization splitting element has not been inexpensive and has high light use efficiency.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a small-sized illumination optical device and a projection display device which are inexpensive and have high light use efficiency.

[0013]

The present invention has the following configuration to achieve the above object.

A first illumination optical device according to the present invention is an illumination optical device for illuminating an image forming means for forming an image, and comprises a light source for radiating natural light, and a light beam for converging and converging light emitted from the light source. Light from the first condensing means to be made incident, and the first condensing means are split into a first polarized light and a second polarized light whose polarization directions are orthogonal to each other, and one of them is reflected. Polarization separating means for transmitting the other, the second polarized light from the polarized light separating means is incident, reflecting means for reflecting in a predetermined direction, the first polarized light from the polarized light separating means, A second condensing unit that receives the second polarized light reflected by the reflecting unit, converts each of them into substantially parallel light, and emits the light; and the first condensing unit from the second condensing unit. Polarized light and the second polarized light are incident, and each of them is split into a plurality of light beams and emitted. A first lens array plate having a plurality of lens elements, and a plurality of light beams of the first polarized light and the plurality of light beams of the second polarized light from the first lens array plate, respectively. A second lens array plate provided with the first and second lens array plates, and the first polarized light and the second polarized light from the second lens array plate enter, and the first polarized light and the second Polarization rotating means for rotating at least one polarization direction of the polarized light beams so that the polarization directions of the polarized light beams substantially coincide with each other. And a wire grid polarization separating element that polarizes and separates incident light by a metal grid in which a metal is formed in a striped pattern with a period sufficiently smaller than the wavelength of visible light, and wherein the polarization rotating unit is configured to include the first lens. Said from the array plate Wherein the number of light beams is arranged near a position converging each of the second lens array plate.

Further, a second illumination optical device of the present invention is an illumination optical device for illuminating an image forming means for forming an image, wherein the light source emits natural light and the light emitted from the light source is collected. A first condensing means for converging and converging, and light from the first condensing means is incident thereon and separated into a first polarized light and a second polarized light whose polarization directions are orthogonal to each other. Polarized light separating means for reflecting light and transmitting the other light, reflecting means for receiving the second polarized light from the polarized light separating means and reflecting in a predetermined direction, and first polarized light from the polarized light separating means A second polarized light reflected by the reflecting means is incident, the light is converted into substantially parallel light, and the second polarized light is emitted from the second polarized light. The first polarized light and the second polarized light are incident, and are divided into a plurality of light fluxes. A first lens array plate having a plurality of lens elements for emitting light, and a plurality of light beams of the first polarized light and a plurality of light beams of the second polarized light from the first lens array plate are respectively incident thereon. A second lens array plate having a plurality of lens elements, and the first polarized light and the second polarized light from the second lens array plate are incident, and the first polarized light and the A polarization rotating means for rotating at least one of the second polarized lights to make the two polarization directions substantially coincide with each other, wherein the polarization separating means comprises a light converging position by the first condensing means. And a wire grid polarization separating element that polarizes and separates incident light by a metal grid in which a metal is formed in a striped pattern at a period sufficiently finer than the wavelength of visible light, and wherein the polarization rotating means includes: From the lens array plate The plurality of luminous fluxes are arranged near positions where they converge on the second lens array plate, respectively, and the reflecting means comprises a reflecting prism, and the second polarized light passes through a medium of the reflecting prism. It is characterized by doing.

Further, a third illumination optical device of the present invention is an illumination optical device for illuminating an image forming means for forming an image, wherein the light source emits natural light and the light emitted from the light source is collected. First condensing means for converging and converging, and light from the first condensing means is incident, and is separated into a first polarized light and a second polarized light whose polarization directions are orthogonal to each other. Polarization separating means for reflecting the polarized light and transmitting the second polarized light; reflecting means for receiving the second polarized light from the polarized light separating means and reflecting the polarized light in a predetermined direction; The first polarized light from the means and the second polarized light reflected by the reflecting means.
And a second condensing unit for converting each of them into substantially parallel light and emitting the same, and the first and second polarized lights from the second condensing unit. A first lens array plate including a plurality of lens elements into which light is incident, each of which is split into a plurality of light beams, and a plurality of light beams of the first polarized light from the first lens array plate; A second lens array plate including a plurality of lens elements into which a plurality of light beams of the second polarized light are respectively incident; the first polarized light from the second lens array plate and the second polarized light; Polarized light is incident, the first polarized light and the second
Polarization rotating means for rotating at least one polarization direction of the polarized light beams so that the polarization directions of the polarized light beams substantially coincide with each other. And a wire grid polarization separating element that polarizes and separates incident light by a metal grid in which a metal is formed in a striped pattern with a period sufficiently smaller than the wavelength of visible light, and wherein the polarization rotating unit is configured to include the first lens. The plurality of luminous fluxes from the array plate are arranged in the vicinity of positions where they converge on the second lens array plate, respectively, and the reflecting means comprises a back reflection mirror having a reflection film formed on one surface of a parallel plate glass. The back reflection mirror is in close contact with the wire grid polarization separation element on a surface on which the reflection surface is not formed.

According to the first to third illumination optical devices,
An illumination optical device which is small, has high light use efficiency, and is inexpensive can be provided.

Further, in the second illumination optical device, a reflection prism is used as the reflection means, and the second polarized light separated and transmitted through the medium of the reflection prism, so that the light use efficiency is further improved.

Further, in the third illumination optical device, since the back reflection mirror closely attached to the wire grid polarization separation element is used as the reflection means, light loss is reduced, and light utilization efficiency is further improved.

In the first to third illumination optical devices,
The first condensing means may be constituted by an elliptical reflecting mirror. Thus, light from the light source can be converged at a low cost with a small number of parts.

Alternatively, the first condensing means may be constituted by a parabolic mirror and a lens. Accordingly, it is possible to converge the light from the light source while suppressing a decrease in light use efficiency.

In the first to third illumination optical devices, it is preferable that the period of the metal grating of the wire grid polarization splitting element is about 150 nm or less. Thereby, the polarization separation characteristics are improved, and a decrease in light use efficiency can be suppressed.

In the first to third illumination optical devices, it is preferable that the height of the metal grating of the wire grid polarization splitting element is about 200 nm or less. Thereby, the polarization separation characteristics are improved, and a decrease in light use efficiency can be suppressed.

In the first to third illumination optical devices, it is preferable that the metal of the wire grid polarization splitting element is aluminum. Thereby, the metal grid can be formed easily and inexpensively.

In the first to third illumination optical devices, it is preferable that the reflection surface of the reflection means is formed of an aluminum film or a dielectric film. When formed of an aluminum film, the reflection means can be manufactured easily and inexpensively. In addition, when formed of a dielectric film, the reflectance of the reflection surface can be improved, so that light loss can be reduced. In addition, since infrared rays can be transmitted, it is possible to prevent a temperature rise of elements constituting the optical system thereafter. .

In the first to third illumination optical devices, it is preferable that the second condensing means comprises one aspherical lens for reducing spherical aberration. By reducing the spherical aberration, the loss of light can be reduced, and the light use efficiency can be improved. In addition, by using one aspherical lens, the number of parts can be reduced, the structure can be simplified, and downsizing and cost reduction can be achieved.

In the above, it is preferable that the aspherical lens is manufactured by molding. Thereby, an aspherical lens having a desired shape can be manufactured easily and at low cost.

Preferably, the aspherical lens is made of a resin. Thereby, an aspherical lens having a desired shape can be manufactured easily and at low cost.

In the first to third illumination optical devices, it is preferable that the polarization rotating means is a half-wave plate made of a stretched resin film. As a result, inexpensive polarization rotating means can be obtained.

Alternatively, the polarization rotating means may be constituted by a thin film formed by oblique evaporation or the like. This makes it possible to form the polarization rotating means having excellent heat resistance with high positional accuracy.

Next, the first projection type display device of the present invention comprises:
An illumination optical unit including a light source that emits white light; a color separation optical unit that separates white light from the light source into color lights of blue, green, and red color components; and each color light from the color separation optical unit is incident. A projection type display device comprising: an image forming unit that forms an optical image in accordance with a video signal; and a projection lens that projects an optical image formed on the image forming unit onto a screen. The optical means is any one of the first to third illumination optical devices. By using any one of the first to third illumination optical devices of the present invention, it is possible to provide a projection display device that is small, has high light use efficiency, and is inexpensive.

In the first projection display device, three image forming means are provided corresponding to blue, green, and red light, respectively, and further, blue, green, and blue light from the three image forming means are provided.
A color combining optical unit for combining the red emission light may be provided. Thus, the entire spectrum of white light from the light source can be used, so that the light use efficiency is improved and a high-luminance color image can be displayed.

Alternatively, in the first projection type display device, each color light from the color separation optical unit is incident on a common image forming unit, and the projection lens projects a color image formed on the image forming unit. It can also be configured to do so. Since a color image is formed on one image forming unit, a color combining optical unit is not required, and a small-sized and low-cost projection display device can be provided.

In the first projection type display device, a transmission type liquid crystal panel can be used as the image forming means.

Further, the second projection type display device of the present invention comprises:
Illumination optical means including a light source that emits white light, blue, green, and color separation optical means that separates white light from the light source into color lights of respective color components, and each color light from the color separation optical means is Incoming, the incident color light is polarized in a direction orthogonal to 2
Three polarized light separating prisms for separating into three polarized light beams, three image forming means for receiving light from the three polarized light separating prisms, respectively, and forming an optical image according to a video signal, and the three image forming means The light emitted from each of the three polarization splitting prisms is incident after being transmitted therethrough, and a color combining optical unit that combines these three incident lights, and an optical image formed on the image forming unit is screened. A projection type display device having an upper projection lens, wherein the illumination optical means is any one of the first to third illumination optical devices. By using any one of the first to third illumination optical devices of the present invention, it is possible to provide a projection display device that is small, has high light use efficiency, and is inexpensive.

In the second projection display device, a reflective liquid crystal panel can be used as the three image forming means.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an illumination optical device and a projection display device according to the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 shows the configuration of a first illumination optical device of the present invention. As the image forming means, a transmission type liquid crystal panel that modulates light using polarized light is used.

In FIG. 1, reference numeral 30 denotes a lamp as a light source;
Reference numeral 31 denotes an ellipsoidal mirror as a first condensing means for converging and converging light from the lamp 30, 32 a wire grid polarization splitting element, 33 a reflection mirror, and 34 a second condensing means. An aspheric lens, 35 is a first lens array plate,
36 is a second lens array plate, 37 is a half-wave plate as polarization rotating means, 38 is a superimposing lens, 39 is the first illumination optical device of the present invention, 40 is a field lens, and 41 is image forming means. A liquid crystal panel, 50 is a polarization separation element 3
2, the optical axis of the polarized light transmitted through 2, the optical axis 51 of the polarized light reflected by the polarization splitting element 32, the optical axis 52 of the illumination optical device 39, and the light 53 converged by the ellipsoidal mirror 31 and then converged. ,
Numeral 54 indicates a part of the two polarized light beams, which are transmitted through the first and second lens array plates 35 and 36 and enter the liquid crystal panel 41, respectively.

Light emitted from a lamp 30 such as an ultrahigh pressure mercury lamp or a xenon lamp is condensed by an ellipsoidal mirror 31 and then converged at one focal position of the ellipsoidal mirror. In the vicinity of the converging position, the wire grid polarization splitting element 32
Is arranged. The wire grid polarization separation element 32
The light that becomes P-polarized light is transmitted through the incident surface, and the light that becomes S-polarized light is reflected. Therefore, the light incident on the wire grid polarization separation element 32 is separated into two polarized lights whose polarization directions are orthogonal to each other. The traveling direction of the separated S-polarized light is changed to a predetermined direction by the reflection mirror 33. The two separated polarized lights form secondary light source images at one focal position of the ellipsoidal mirror 31 and near the optical axis 52 of the illumination optical device 39, respectively. FIG.
The light 53 is collected by the ellipsoidal mirror 31, converged, and split by the wire grid polarization splitting element 32 into two polarized lights.

The separated P-polarized light and S-polarized light are converted into substantially parallel light by the aspherical lens 34 and then enter the first lens array plate 35. The first lens array plate 35 has a large number of minute rectangular lens elements arrayed on the same plane. The luminous flux of each polarized light incident on the first lens array plate 35 is divided into a number of luminous fluxes by a number of lens elements. A large number of split light beams are
Converge on a large number of minute rectangular lens elements arranged and formed on the lens array plate 36 of FIG. The multiple lens elements of the first lens array plate 35 and the multiple lens elements of the second lens array plate 36 correspond one-to-one. One focus position of the elliptical mirror 31 and the second lens array plate 36
And have a substantially conjugate relationship. On each lens element of the second lens array plate 36, a minute secondary light source image formed by polarization-separated P-polarized light and a minute secondary light source image formed by S-polarized light are formed at different positions. The focal length of the lens element of the first lens array plate 35 is equal to the distance between the first lens array plate 35 and the second lens array plate 36. The lens element of the first lens array plate 35 has a rectangular opening similar to the liquid crystal panel 41. The focal length of the lens elements of the second lens array plate 36 is determined in consideration of the power of the lens elements so that the surface of the first lens array plate 35 and the surface of the liquid crystal panel 41 have a substantially conjugate relationship. ing.

On the exit surface of the second lens array plate 36,
Only half the area of the aperture of each lens element is １ ／
A wave plate 37 is attached. Therefore, of the many light beams emitted from the second lens array plate 36, the light beam of the P-polarized light passes through the half-wave plate 37, and at this time, the polarization direction is rotated and converted to S-polarized light. . On the other hand, the luminous flux of the S-polarized light having the secondary light source image formed at a position different from the P-polarized light in the lens element of the second lens array 36 passes through the second lens 37 without passing through the half-wave plate 37. The light exits the array plate 36. As described above, the two polarized lights separated by the wire grid polarization separating element 32 have the same polarization direction when exiting the second lens array plate 36 and the half-wave plate 37, and have one common polarized light. It becomes the polarized light of the direction.

The superimposing lens 38 transmits light emitted from each lens element of the second lens array plate 36 to the liquid crystal panel 41.
This is a lens for superimposing illumination on the top. A large number of light beams emitted from the second lens array plate 36 are
8. After being transmitted through the field lens 40 and refracted, it is superimposed on the liquid crystal panel 41 to illuminate the liquid crystal panel 41 uniformly. The field lens 40 is for condensing light illuminating the liquid crystal panel 41 on a pupil plane (not shown) of the projection lens. The pupil plane of the projection lens and the surface of the second lens array plate 36 have a substantially conjugate relationship. The light flux 54 is separated by the wire grid polarization splitting element 32, and then passes through the first and second lens array plates 35 and 36, and passes through the liquid crystal panel 4.
1 shows the appearance of some light rays of two polarized lights illuminating 1.

As described above, the first illumination optical device 39 includes:
After the natural light from the lamp 30 is efficiently polarized and separated, it can be efficiently converted into polarized light in one direction to uniformly illuminate the image forming means 41.

FIG. 2 shows the configuration of the wire grid polarization splitting element. Wire grid polarization separation element 32
Is formed by forming a stripe-shaped metal grid 43 parallel to each other with a metal such as aluminum on a glass substrate 42.
The width of each metal stripe constituting the metal grid 43 is b, the height is h, and the arrangement period (pitch) is d. When the metal grating is formed with a sufficiently small cycle d of about 1/5 or less with respect to the wavelength of the incident light, the light of the electric field component oscillating perpendicular to the grid period direction 44 is reflected, and the light of the electric field component oscillating in parallel is It is transmitted, hardly absorbs light, and can be efficiently polarized and separated. In the case of the configuration of FIG.
Is incident at an incident angle θ, the reflected light 46 becomes S-polarized light and the transmitted light 47 becomes P-polarized light with respect to the incident surface of the wire grid polarization separation element 32. The wire grid polarization splitting element 32 according to an example of the present embodiment includes a glass substrate 4
2 has a width b of about 70 nm,
A large number of stripes made of aluminum having a rectangular cross section having a height h of about 150 nm and a period d of about 140 nm are formed. Such a submicron fine metal grating is manufactured, for example, as follows. Number n on glass substrate
An aluminum base film having a conductivity of m is formed, and a resist pattern is formed by electron beam lithography. Next, aluminum having a predetermined thickness is deposited, and unnecessary aluminum is selectively removed by lift-off to form a metal grid.
Further, the conductive base film remaining other than the metal lattice is removed by etching, or oxidized and transparentized by heat treatment. In recent years, with the development of semiconductor technology, simple microfabrication of the submicron as described above can be manufactured relatively easily at low cost.

The wire grid polarization splitting element has a smaller dependency on the incident angle of the transmittance and the reflectance than the thin-film polarization splitting prism utilizing the Brewster angle, and can perform the polarization splitting with high efficiency. Further, since it is made of metal and glass, it has excellent heat resistance and light resistance. Further, it can be manufactured at lower cost than the polarization separation prism array 5 shown in FIG.

FIG. 3 shows the spectral transmittance of the wire grid polarization splitting element. The P-polarized light transmittance and S in the case where the incident angle is the reference incident angle of 45 degrees and 30 degrees, respectively.
9 shows characteristics of polarized light transmittance. In FIG. 3, the incident angle is 4
The case of 5 degrees is indicated by a solid line, and the case of 30 degrees is indicated by a dotted line. In the blue wavelength region, the transmittance of P-polarized light and the reflectance of S-polarized light slightly decrease, but the incident angle is the reference incident angle 4.
In the case of 5 degrees, a transmittance of P-polarized light and a reflectance of S-polarized light of 90% or more are obtained on average. Even when the angle of incidence is 30 degrees, which is -15 degrees smaller than the reference angle of incidence, an average of 84% or more of P-polarized light transmittance and S-polarized light reflectance can be obtained. By the way, in the case of the polarization splitting prism, if the incident angle becomes smaller than the reference incident angle of 45 degrees by about -15 degrees, P
The polarization transmittance becomes 40 to 50%.

In the illumination optical device 39 described above, the wire grid polarization separation element 32 having high transmittance and reflectance of the polarized and separated light irrespective of the incident angle, and having excellent heat resistance and light resistance is removed from the lamp 30. Are arranged in the vicinity of the position where the light is converged. For this reason, the wire grid polarization separation element 32 can be made very small, and a low cost and high efficiency polarization separation element can be configured.

Next, the separated two polarized lights are respectively converged to different positions near the optical axis 52 of the illumination optical device 39, and then the aspheric lens 34 and the first lens array plate 35
Synthesized by Thereafter, the two polarized lights are respectively converged at different positions on each lens element of the second lens array plate 36 to separate and form a secondary light source image. A 波長 wavelength plate 37 is arranged near the second lens array plate 36. The half-wave plate corresponds to the position of the secondary light source image formed by the P-polarized light in the secondary light source image formed by the two polarized lights, and is formed at about the opening of each lens element of the second lens array plate 36. Affixed to 1/2 area. Accordingly, the polarization direction of the P-polarized light can be rotated to the S-polarization direction by the half-wave plate 37 to make the polarization directions uniform. The half-wave plate 37 has relatively low heat resistance, but is made of an inexpensive stretched film. The half-wave plate 37 is arranged at a position where the light beam is divided into a large number, and at a position where the spread angle of the incident light is small. Therefore, the half-wave plate 37
Can be configured at low cost, and the polarization direction of the polarized light that is transmitted with high efficiency can be rotated while ensuring reliability.

In FIG. 1, the first condensing means is an ellipsoidal mirror 31. However, the first condensing means may be constituted by a parabolic mirror and a condensing lens. FIG. 4 shows a first condenser means constituted by a parabolic mirror and a condenser lens. Reference numeral 30 denotes a lamp, 60 denotes a parabolic mirror, and 61 denotes a condenser lens. In the case of the ellipsoidal mirror 31 shown in FIG. 1, a part of the light reflected by the reflection surface near the lamp among the reflection surfaces of the ellipsoidal mirror 31 is blocked by the tip of the lamp 30 and is not converged. Is slightly reduced. However, when a substantially parallel light beam is obtained by the parabolic mirror 60 and then converged by the condenser lens 61, there is no light blocking at the tip of the lamp 30 and light use efficiency is improved. Can be higher.

The second focusing means is an aspheric lens 34 manufactured by molding. By making the lens shape an aspherical shape, spherical aberration can be reduced, and 2 converged near the optical axis 52.
The two polarized lights can be efficiently made incident on the first lens array plate 35. When heat resistance is required, the aspheric lens 34 is desirably a glass molded product. When heat resistance is not required, a relatively inexpensive resin molded product may be used.

The reflection mirror 33 is a reflection film formed by forming an aluminum film or a dielectric film on a glass substrate. When an aluminum film is used for the reflection film, the reflection mirror can be constructed relatively inexpensively. In addition, when a dielectric film is used as the reflective film, a higher reflectance can be obtained and infrared rays can be transmitted, so that heat rays can be cut.

As the polarization rotating means, a thin-film wave plate composed of a thin film may be used. The thin film wave plate utilizes a phenomenon that birefringence occurs when a light beam is perpendicularly incident on a film surface of an obliquely deposited thin film. The retardation can be controlled by adjusting the thickness of the obliquely deposited film. Although a thin-film wave plate is more expensive than a wave plate using a stretched resin film, since it has excellent heat resistance, cooling means is not required. Further, the arrangement accuracy with respect to the second lens array plate 36 can be increased.

In the above example, the polarization rotating means is disposed in the pass region of the P-polarized light so that the P-polarized light separated from the polarized light is converted into the S-polarized light. The light may be disposed in a region where the S-polarized light passes so that the light is converted into the P-polarized light.

First and second lens array plates 35 and 36
As the number of divisions (the number of lens elements) increases, more uniform illumination becomes possible. The first and second lens array plates 3
5, 36 are cheaper if they are smaller. In the conventional illumination optical device using the polarization separation prism array 5 shown in FIG. 12, the arrangement pitch of the polarization separation prism needs to be approximately １ ／ of the lens element pitch of the second lens array plate 4. When the size of the two-lens array plate 4 is extremely reduced, it becomes necessary to further reduce the arrangement pitch of the polarization splitting prisms, thereby lowering the arrangement accuracy and lowering the light use efficiency.
Also in the configuration of the present invention, when the second lens array plate 36 is reduced in size, the second lens array plate 36 is similarly disposed near the lens array plate 36.
Although there is a restriction that the half-wave plate 37 also needs to be small, since the half-wave plate 37 is a single film,
Its arrangement is easy. Therefore, even if the number of divisions of the lens array plate is relatively large, a decrease in efficiency due to the downsizing of the lens array plate hardly occurs. Therefore, the illumination optical device can be downsized.

FIG. 5 shows another configuration of the first illumination optical device. The difference from the configuration of FIG. 1 is that a reflection mirror 73 is arranged for light transmitted through the polarization splitting element.

The light emitted from the lamp 70 is transmitted to the elliptical mirror 7.
After being converged by 1, it converges to one focal position of the elliptical mirror 71. Near the convergence position, a wire grid polarization splitting element 72 is arranged. The light incident on the wire grid polarization separation element 72 transmits P-polarized light to the incident surface, reflects S-polarized light, and separates the polarized light into two polarized lights having orthogonal polarization directions. The separated P-polarized light enters the reflection mirror 73, is reflected, and changes the traveling direction of the light to a predetermined direction. The separated two polarized lights form secondary light source images near the optical axis 92 of the illumination optical device 79, respectively. FIG. 5 shows a state of a light beam 93 which is condensed by an ellipsoidal mirror 71 from a lamp 70, converged, and separated into two polarized lights by a wire grid polarization separating element 72. In FIG. 5, reference numeral 90 denotes the polarization separation element 7.
Reference numeral 91 denotes the optical axis of the P-polarized light transmitted through the reflection mirror 73, and reference numeral 92 denotes the optical axis of the illumination optical device 79.

The separated P-polarized light and S-polarized light are converted into substantially parallel light by the aspheric lens 74, and then enter the first lens array plate 75. The luminous flux of each polarized light incident on the first lens array plate 75 is divided into a large number of luminous fluxes by a large number of lens elements formed thereon. A large number of split light beams are supplied to the second lens array plate 7.
The light converges on a large number of minute lens elements arranged and formed on the light emitting element 6. On each lens element of the second lens array plate 76, minute secondary light source images formed by polarization-separated P-polarized light and S-polarized light are formed at different positions. Among the many light beams emitted from the second lens array plate 76, the light beam of the P-polarized light passes through the half-wave plate 77, and at this time, the polarization direction is rotated and converted to S-polarized light. On the other hand, the second
The luminous flux of the S-polarized light having the secondary light source image formed at a position different from the P-polarized light in the lens element of the lens array 76 is 1 /
The light is emitted from the second lens array plate 76 without passing through the two-wavelength plate 77. As described above, the two polarized lights separated by the wire grid polarization separating element 72 have the same polarization direction when exiting the second lens array plate 76 and the half-wave plate 77, and have one common polarized light. It becomes the polarized light of the direction.

A large number of light beams emitted from the second lens array plate 76 are passed through a lens 78 for superposition and a field lens 80.
After being transmitted and refracted, it is superimposed on the liquid crystal panel 81,
The liquid crystal panel 81 is uniformly illuminated with high efficiency. Luminous flux 94
Shows the appearance of a part of the two polarized lights that illuminate the liquid crystal panel 81 after passing through the first and second lens array plates 75 and 76 after being separated by the wire grid polarization separating element 72. I have.

As described above, the illumination optical device 79 of FIG. 5 efficiently polarizes and separates natural light from the lamp 70,
The light is efficiently converted into polarized light in one direction, and
1 can be uniformly illuminated.

As compared with the configuration shown in FIG. 1, a reflection mirror for reflecting P-polarized light transmitted through the wire grid polarization splitting element 72 is arranged near the wire grid polarization splitting element 72. Without placing
The illumination optical device can be made compact.

As described above, the first illumination optical devices 39 and 79 of the present invention collect the light from the light source and arrange the wire grid polarization separation element in the vicinity of the converged position to form two polarized light beams. And converts the polarization direction of one of the two polarized lights to the other at the position where the polarized light is incident at a relatively small incident angle near the second lens array plate. A compact and highly efficient illumination optical device can be configured.

(Embodiment 2) FIG. 6 shows the configuration of a second illumination optical device according to the present invention. As the image forming means, a transmission type liquid crystal panel that modulates light using polarized light is used.

In FIG. 6, reference numeral 100 denotes a discharge lamp as a light source; 101, an elliptical mirror as a first light condensing means for condensing light from the lamp 100; and 102, a wire grid polarization separating element; 104 is an aspheric lens as a second light condensing means, 105 is a first lens array plate, 1
Reference numeral 06 denotes a second lens array plate, 107 denotes a half-wave plate serving as a polarization rotating unit, 108 denotes a superimposing lens, 109 denotes a second illumination optical device of the present invention, 110 denotes a field lens, and 111 denotes an image forming unit. 120, the optical axis of the polarized light transmitted through the polarization splitting element 102, 121, the optical axis of the polarized light reflected by the polarization splitting element 102, 122, the optical axis of the illumination optical device 109, and 123, the elliptical mirror 101. The light 124 converged after being condensed by the reference numeral 124 indicates a part of the two polarized light separated by polarization, transmitted through the first and second lens array plates 105 and 106 and incident on the liquid crystal panel 111. ing.

The above is the same as the first embodiment shown in FIG. 1 in the first embodiment, except that a reflecting prism 103 is used as a reflecting means. The reflection prism 103 is a right-angle prism having a reflection film formed on the oblique side.

The light emitted from the lamp 100 is converged by the ellipsoidal mirror 101 and then converges to one focal position of the ellipsoidal mirror. In the vicinity of the convergence position, a wire grid polarization splitting element 102 is arranged. The light incident on the wire grid polarization splitting element 102 is transmitted as P-polarized light with respect to the incident surface, reflected as S-polarized light, and separated into two polarized lights whose polarization directions are orthogonal to each other. The S-polarized light reflected and separated by the wire grid polarization separation element 102 enters the reflection prism 103. The incident light propagates through the reflecting prism 103, is reflected by the reflecting film formed on the oblique side, changes the traveling direction of the light in a predetermined direction, and propagates through the reflecting prism 103 again.
Emitted from 03. The separated two polarized lights are located at one focal point of the ellipsoidal mirror 101 and the illumination optical device 10
A secondary light source image is formed in the vicinity of each of the optical axes 122 of No. 9.
FIG. 6 shows that the light from the lamp 100 is condensed and converged by the ellipsoidal mirror 101, and
2 shows the appearance of the light beam 123 separated into two polarized lights. Reference numeral 120 denotes an optical axis of the P-polarized light transmitted through the polarization splitter 102, 121 denotes an optical axis of the S-polarized light reflected by the polarization splitter 102, and 122 denotes an optical axis of the illumination optical device 109.

After the separated P-polarized light and S-polarized light are converted into substantially parallel light by the aspheric lens 104,
To the lens array plate 105. The first lens array plate 105 has a large number of minute lens elements arrayed on the same plane. The luminous flux of each polarized light incident on the first lens array plate 105 is divided into a number of luminous fluxes by a number of lens elements. Many split luminous fluxes are
Each of the light beams converges on a number of minute lens elements arranged and formed on the second lens array plate 106. Elliptical mirror 10
One focal position of the first lens array plate 106 and the second lens array plate 106 are configured to have a substantially conjugate relationship. On each lens element of the second lens array plate 106, a polarization-separated P
A small secondary light source image by polarized light and a small secondary light source image by S-polarized light are formed at different positions.

The output surface of the second lens array plate 106 has only one half of the aperture of each lens element.
A / 2 wavelength plate 107 is attached. Therefore, among the many light beams emitted from the second lens array plate 106, the light beam of the P-polarized light passes through the half-wave plate 107, and at this time, the polarization direction is rotated and converted to S-polarized light. . on the other hand,
The luminous flux of the S-polarized light, which forms the secondary light source image at a position different from the P-polarized light in the lens element of the second lens array 106, does not pass through the half-wave plate 107, The beam 106 is emitted. As described above, the two polarized lights separated by the wire grid polarization separating element 102 are combined with the second lens array plate 106 and the half-wave plate 1
07 are emitted, the polarization directions are aligned, and the light becomes polarized light in one common polarization direction.

A large number of light beams emitted from the second lens array plate 106 are transmitted through a superimposing lens 108 and a field lens 110, are refracted, and are superimposed on a liquid crystal panel 111. Illuminate evenly.
The light beam 124 is separated by the wire grid polarization splitting element 102, and then the first and second lens array plates 105, 1
6 shows the appearance of a part of the two polarized lights that illuminate the liquid crystal panel 111 by passing through the liquid crystal panel 06.

As described above, the illumination optical device 109 efficiently separates the natural light from the lamp 100 into polarized light, and then efficiently converts the light into polarized light in one direction.
Can be uniformly illuminated.

Next, the effect of the reflecting prism 103 of the second illumination optical device 109 will be described.
This will be described in comparison with (FIG. 1).

In the first illumination optical device 39 (FIG. 1), the position where the P-polarized light transmitted through the wire grid polarization separation element 32 converges to form a secondary light source image, and the position where the P-polarized light is reflected by the wire grid polarization separation element 32 are reflected. The position at which the S-polarized light converges and forms a secondary light source image is different from the aspheric lens 34 in the optical path length in the light traveling direction. Aspheric lens 34
Is determined so that the light emitted from each of the converged P-polarized light and S-polarized light emitted from the secondary light source images can be converted into parallel light and emitted. For this reason, the aspherical lens 3 is designed to maximize the light use efficiency of the illumination optical device at an intermediate position between the convergence position of the P-polarized light and the convergence position of the S-polarized light.
4 shape is decided. Therefore, from the viewpoint of the light use efficiency, the convergence position of the P-polarized light and the convergence position of the S-polarized light are both slightly deviated from the optimum positions, resulting in a decrease in the light use efficiency. The light use efficiency decreases as the relative distance between the convergence position of the P-polarized light and the convergence position of the S-polarized light increases. FIG. 7 shows the relative light use efficiency of the illumination optical device with respect to the relative distance between the convergence position of the P-polarized light and the convergence position of the S-polarized light. In FIG. 7, Pp denotes the first illumination optical device 3.
9 (FIG. 1) shows the convergence position of the P-polarized light, and Ps also shows the convergence position of the S-polarized light. As shown,
It can be seen that the relative efficiency L0 for both P-polarized light and S-polarized light is reduced by the optical relative distance L0 between Pp and Ps.

On the other hand, the second illumination optical device 10
In 9, the S-polarized light reflected by the wire grid polarization splitting element 102 enters the reflecting prism 103. By transmitting the S-polarized light through the reflecting prism 103, the optical distance is reduced. That is, as shown in FIG. 7, the convergence position of the S-polarized light moves to Ps ′. Accordingly, the optical relative distance L1 between the convergence position Pp of the P-polarized light and the convergence position Ps' of the S-polarized light is shorter than the relative distance L0 of the first illumination optical device 39 (FIG. 1), and the relative efficiency is improved. Can be done. As described above, the second illumination optical device 109 uses the reflection prism as the reflection unit, and configures one of the polarization-separated polarized light to pass through the medium of the reflection prism, thereby providing the first illumination optical device 109 with the first illumination optical device. The light use efficiency is further improved as compared with the device 39 (FIG. 1).

As described above, the second illumination optical device 109
Is a method that focuses light from a light source, arranges a wire grid polarization separating element near the converged position, separates the polarized light into two polarized lights, and uses a reflecting prism as a reflection means to pass one polarized light through the prism. At the position where polarized light is incident at a relatively small angle of incidence near the second lens array plate, the polarization direction of one of the two polarized lights is converted to the other polarization direction at the position near the second lens array plate. In addition, a compact and highly efficient illumination optical device can be configured.

FIG. 8 shows another configuration of the second illumination optical device. 6 is different from the configuration in FIG. 6 in that a reflection prism 133 is disposed for light transmitted through the polarization beam splitter.

The light emitted from the lamp 130 is converged by the ellipsoidal mirror 131 and then converges to one focal position of the ellipsoidal mirror 131. In the vicinity of the convergence position, a wire grid polarization separation element 132 is arranged. The light incident on the wire grid polarization separating element 132 has a P
The polarized light is transmitted, and the s-polarized light is reflected and separated into two polarized lights having different polarization directions. The separated P-polarized light enters the reflection prism 133, is reflected by the reflection film formed on the oblique side, and changes the traveling direction of the light to a predetermined direction. The separated two polarized lights are used by the illumination optical device 13.
A secondary light source image is formed in the vicinity of the optical axis 152 of No. 9 respectively.
FIG. 8 shows that the light from the lamp 130 is condensed and converged by the ellipsoidal mirror 131,
2 shows the appearance of a light beam 153 separated into two polarized lights. 8, reference numeral 150 denotes the optical axis of the S-polarized light reflected by the polarization separation element 132, and 151 denotes the polarization separation element 102.
, The optical axis of the P-polarized light that is reflected by the reflection film of the reflection prism 133 and exits the reflection prism 133, and 152 is the optical axis of the illumination optical device 139.

After the separated P-polarized light and S-polarized light are converted into substantially parallel light by the aspheric lens 134,
To the lens array plate 135. The luminous flux of each polarized light incident on the first lens array plate 135 is divided into a large number of luminous fluxes by a large number of lens elements formed thereon. A large number of split light fluxes converge on a large number of minute lens elements arranged and formed on the second lens array plate 136, respectively. On each lens element of the second lens array plate 136, a minute secondary light source image formed by polarized P-polarized light and a minute secondary light source image formed by S-polarized light are formed at different positions. Among the many light beams emitted from the second lens array plate 136, the light beam of the P-polarized light passes through the half-wave plate 137, and at this time, the polarization direction is rotated and converted to S-polarized light. On the other hand, the second lens array 1
The luminous flux of the S-polarized light having the secondary light source image formed at a position different from the P-polarized light in the lens element 36 is a half-wave plate 137
Out of the second lens array plate 136 without passing through. Thus, the wire grid polarization splitting element 13
The two polarized lights separated by 2 have the same polarization direction when exiting the second lens array plate 136 and the half-wave plate 137, and become polarized light in one common polarization direction.

A large number of light beams emitted from the second lens array plate 136 are transmitted through the superimposing lens 138 and the field lens 140, are refracted, and are superimposed on the liquid crystal panel 141. Illuminate evenly.
After the light beam 154 is separated by the wire grid polarization separation element 132, the first and second lens array plates 135, 1
The appearance of a part of the two polarized lights that illuminate the liquid crystal panel 141 through the liquid crystal panel 141 is shown.

As described above, the illumination optical device 139 of FIG.
After the natural light from the lamp 130 is efficiently polarized and separated, it can be efficiently converted into polarized light in one direction, and the image forming unit 141 can be uniformly illuminated.

As compared with the configuration of FIG. 6, a reflecting prism for reflecting P-polarized light transmitted through the wire grid polarization separating element 132 is arranged near the wire grid polarization separating element 132, so that a reflecting means is newly provided. The illumination optical device can be made compact without disposing the illumination optical device.

(Embodiment 3) FIG. 9 shows the configuration of a third illumination optical device of the present invention. As the image forming means, a transmission type liquid crystal panel that modulates light using polarized light is used.

In FIG. 9, reference numeral 160 denotes a lamp as a light source, 161 denotes an elliptical mirror as a first light condensing means for converging and converging light from the lamp 160, and 162 denotes a wire grid polarization splitting element and 164. Is an aspheric lens as a second light condensing means, 165 is a first lens array plate, 16
6 is a second lens array plate, 167 is a half-wave plate as polarization rotating means, 168 is a superimposing lens, 169 is a third illumination optical device of the present invention, 170 is a field lens,
171 is a liquid crystal panel as an image forming means, 180 is the optical axis of the polarized light reflected by the polarization separation element 162, 181 is the optical axis of the polarized light transmitted through the polarization separation element 162, 182 is the optical axis of the illumination optical device 169, Reference numeral 183 denotes a light beam that converges after being converged by the ellipsoidal mirror 161, and 184 denotes a light beam that is transmitted through the first and second lens array plates 165 and 166 and is incident on the liquid crystal panel 171. Some rays are shown.

The above configuration is the same as that of the first embodiment shown in FIG. 5 in the first embodiment, except that the reflection means is constituted by using a back reflection flat glass plate 163 bonded to a wire grid polarization separation element 162. That is the point. The back reflection flat glass 163 is formed by forming a reflection film such as aluminum or a dielectric film on one surface of a parallel flat glass, and the surface on which the reflection film is not formed is joined to the wire grid polarization separation element 162. .

The light emitted from the lamp 160 is condensed by the ellipsoidal mirror 161 and then converges at one focal position of the ellipsoidal mirror. Near the convergence position, a wire grid polarization splitting element 162 is arranged. The light incident on the wire grid polarization separation element 162 transmits P-polarized light with respect to the incident surface, reflects S-polarized light, and is separated into two polarized lights whose polarization directions are orthogonal to each other. The separated P-polarized light passes through the wire grid polarization splitting element 162,
The light enters the back reflection flat glass 163, is reflected by the reflection surface of the flat glass, is changed in the traveling direction of light in a predetermined direction, is again incident on the wire grid polarization separation element 162, and is transmitted therethrough. The separated two polarized lights are located at one focal point of the ellipsoidal mirror 161 and the illumination optical device 1
A secondary light source image is formed near the optical axis 182 of each of the 69 light sources. FIG. 9 shows that the light from the lamp 160 is
The light beam 183 is condensed, converged, and split by the wire grid polarization splitting element 162 into two polarized lights. Reference numeral 180 denotes the optical axis of the S-polarized light reflected by the polarization separation element 162, 181 denotes the light transmitted through the polarization separation element 162, is reflected by the reflection surface of the rear-surface reflection flat glass 163, and is emitted from the wire grid polarization separation element 162. P
The optical axis of the polarized light, 182, is the optical axis of the illumination optical device 169.

The separated P-polarized light and S-polarized light are converted into substantially parallel light by the aspheric lens 164,
To the lens array plate 165. The first lens array plate 165 has a large number of minute lens elements arrayed on the same plane. The luminous flux of each polarized light that has entered the first lens array plate 165 is split into a number of luminous fluxes by a number of lens elements. Many split luminous fluxes are
Each of the light beams converges on a number of minute lens elements arranged and formed on the second lens array plate 166. On each lens element of the second lens array plate 166, a minute secondary light source image formed by polarized P-polarized light and a minute secondary light source image formed by S-polarized light are formed at different positions.

The output surface of the second lens array plate 166 has only one half of the aperture of each lens element.
A / 2 wavelength plate 167 is attached. Therefore, among the many light beams emitted from the second lens array plate 166, the light beam of the P-polarized light passes through the half-wave plate 167, and at this time, the polarization direction is rotated and converted to S-polarized light. . on the other hand,
The luminous flux of the S-polarized light having the secondary light source image formed at a position different from the P-polarized light in the lens element of the second lens array 166 passes through the half-wave plate 167 without passing through the second lens array plate. Emit 166. As described above, the two polarized lights separated by the wire grid polarization separating element 162 are combined with the second lens array plate 166 and the half-wave plate 1
When the light is emitted from the light source 67, the polarization directions are aligned, and the light is polarized in one common polarization direction.

A large number of light beams emitted from the second lens array plate 166 are transmitted through the superimposing lens 168 and the field lens 170, are refracted, and are superimposed on the liquid crystal panel 171. Illuminate evenly.
The light beam 184 is separated by the wire grid polarization separation element 162, and then the first and second lens array plates 165, 1
The state of a part of the two polarized lights that illuminate the liquid crystal panel 171 through the light 66 is shown.

As described above, the second illumination optical device 169
After the natural light from the lamp 160 is efficiently polarized and separated, it can be efficiently converted to polarized light in one direction to uniformly illuminate the image forming unit 171.

Next, regarding the effect of the rear-surface reflecting flat glass 163 of the second illumination optical device 169, the first illumination optical device 39 (FIG. 1), the illumination optical device 79 (FIG. 5) and the second
Illumination optical device 109 (FIG. 6) and illumination optical device 139
This will be described in comparison with (FIG. 8).

In the first and second illumination optical devices, the wire grid polarization separation element and the reflection mirror or the reflection prism as the reflection means are arranged separately. Accordingly, light loss occurs in the wire grid polarization splitting element and the reflection mirror or the reflection prism. On the other hand, in the third illumination optical device 169, the wire grid polarization separation element 1
62 and the back surface reflection flat glass 163 which is the reflection means are adhered to each other. Therefore, there is no light loss in this portion. Therefore, polarization separation can be performed with higher efficiency.

As described above, the third illumination optical device 169
The light from the light source is condensed, a wire grid polarized light separating element is arranged near the converged position, separated into two polarized lights, and a back reflecting flat glass bonded to the polarized light separating element is used as a reflection means, At the position where the polarized light is incident at a relatively small incident angle near the second lens array plate, one of the two polarized lights is converted to the other polarized light, so that it is very low cost and compact. A very efficient illumination optical device can be constructed.

(Embodiment 4) FIG. 10 shows a configuration of a first projection display apparatus of the present invention. As the image forming means, three transmissive liquid crystal panels that modulate light using polarized light are used.

In FIG. 10, reference numeral 200 denotes a lamp as a light source; 201, an ellipsoidal mirror as a first condensing means for converging and converging light from the lamp 200; 202, a wire grid polarization separation element; Is a reflection mirror, 204
Is an aspheric lens as a second light collecting means, 205 is a first lens array plate, 206 is a second lens array plate, 20
7 is a half-wave plate as a polarization rotating means, 208 is a superimposing lens, 210 is a reflecting mirror for bending the optical path, 211
Is the optical axis of the polarized light transmitted through the polarization separation element 202, 212
The optical axis of the polarized light reflected by the polarization splitting element 202, 213 is the optical axis of the illumination optical device 209, 214 is the form of the light beam converged by the elliptical mirror 201 and then converged, and 209 is the illumination optical device of the present invention. is there.

Reference numeral 220 denotes a red transmitting dichroic mirror, reference numeral 221 denotes a green reflecting dichroic mirror, and reference numeral 222 denotes a dichroic mirror.
Is a color separation optical unit composed of a red transmitting dichroic mirror 220 and a green reflecting dichroic mirror 221. 223, 224, 225 are reflection mirrors, 22
6, 227 are relay lenses; 228, 229, and 230 are field lenses; 231, 232, and 233 are incident-side polarizing plates; 234, 235, and 236 are transmissive liquid crystal panels that are image forming means. Reference numerals 237, 238, and 239 denote polarizing plates on the emission side; 242, a dichroic prism which is a color combining optical means composed of a dichroic mirror 240 for red reflection and a dichroic mirror 241 for blue reflection; and 243, a projection lens.

The illumination optical device 209 is provided with a reflection mirror 210 in the first illumination optical device 39 (FIG. 1) and an optical axis 213.
Has the same configuration as that of the first illumination optical device 39 except that is bent.

The polarized light obtained by converting the natural light from the lamp 200 with high efficiency by the illumination optical device 209 is incident on the color separation optical means 222. The light incident on the color separation optical means 222 is a red transmitting dichroic mirror 220,
By the dichroic mirror 221 of green reflection, blue, green,
It is separated into each color light of red. The green light is transmitted through the field lens 228 and the polarizing plate 231 on the incident side, and is incident on the liquid crystal panel 234. After the red color light is reflected by the reflection mirror 223, the field lens 229 and the polarizing plate 23 on the incident side are reflected.
2 and enter the liquid crystal panel 235. The blue light passes through the relay lenses 226 and 227 and is reflected by the reflection mirror 22.
The light is reflected by 4, 225, passes through the field lens 230 and the polarizing plate 233 on the incident side, and then enters the liquid crystal panel 236. The three liquid crystal panels 234, 235, and 236 are of an active matrix type, and control a voltage applied to a pixel according to a video signal to control the corresponding polarizing plate 2 on the emission side.
Light transmitted through 37, 238, and 239 is modulated to form green, red, and blue images, respectively. Liquid crystal panels 234, 23
5, 236, and the dichroic prism 242, which is a color synthesizing optical means, for the color light transmitted through the output side polarizing plates 237, 238, and 239, the red and blue color lights are respectively red-reflected dichroic mirror 240 and blue-reflected dichroic. After being reflected by the mirror 241 and combined with green color light, it is enlarged and projected on a screen (not shown) by the projection lens 243.

The first projection display device uses an inexpensive and small-sized illumination optical device 209 capable of converting natural light into one-way polarized light with high efficiency and uniform illumination, and three liquid crystal panels. Therefore, a very bright and high-resolution projected image can be formed.

As described above, the first projection type display device has a high efficiency of polarization separation even at a relatively large incident angle, and is a small wire grid polarization separation element 202 excellent in heat resistance and light resistance. And a half-wave plate 207 that is arranged near the second lens array plate 206 having a small incident angle of incident light and rotates the polarization direction. Equipment cost reduction,
There is a very great effect that the light use efficiency can be improved while the size is reduced, and the brightness of the projection display device can be increased.

FIG. 10 shows an example in which the illumination optical device 209 having the same configuration as the first illumination optical device shown in FIG. 1 is used. Any of the illumination optical devices described in the first to third embodiments may be used.

(Embodiment 5) FIG. 11 shows the configuration of a second projection type display apparatus according to the present invention. As the image forming means, three reflective liquid crystal panels are used.

In FIG. 11, reference numeral 300 denotes a lamp as a light source; 301, an elliptical mirror as a first light condensing means for converging and converging light from the lamp 300; 302, a wire grid polarization separating element; Is a reflection mirror, 304
Is an aspheric lens as a second light condensing means, 305 is a first lens array plate, 306 is a second lens array plate, 30
7 is a half-wave plate which is a polarization rotating means, 308 is a superimposing lens, 310 is a reflecting mirror for bending the optical path, 311
Are the optical axes of the polarized light transmitted through the polarization separation element 302, 312
313 denotes the optical axis of the polarized light reflected by the polarization separation element 302;
, An optical axis of the illumination optical device 309;
The light beam 309 converged after being converged by the illumination optical device 309 of the present invention.

Reference numeral 330 denotes a blue reflecting dichroic mirror; 331, a green reflecting dichroic mirror;
Is a color separation optical unit composed of a dichroic mirror 330 for reflecting blue and a dichroic mirror 331 for reflecting green. 333 is a reflection mirror, 334, 335, 33
6 is a polarized light separating film 3 using Brewster's angle.
Polarization splitting prism with 37, 338, 339, 34
Reference numerals 0, 341 and 342 denote reflective liquid crystal panels which are image forming means, and 345 denotes a dichroic mirror 343 which reflects red light.
A dichroic prism 34 which is a color combining optical means composed of
Reference numeral 6 denotes a projection lens, and 347 and 348 denote 板 wavelength plates.

The illumination optical device 309 is provided with a reflection mirror 310 in the first illumination optical device 39 (FIG. 1) and an optical axis 313.
Has the same configuration as that of the first illumination optical device 39 except that is bent.

The polarized light obtained by subjecting the natural light from the lamp 300 to polarization conversion with high efficiency by the illumination optical device 309 enters the color separation optical means 332. The light incident on the color separation optical means 332 is reflected by a blue reflecting dichroic mirror 330,
The blue, green,
It is separated into each color light of red. The separated green, red, and blue light components are respectively separated into polarization separation prisms 334, 335, and 336.
Incident on. Polarization splitting prisms 334, 335, 336
Is a polarization separation film 33 composed of a dielectric multilayer film
It is a prism having 7, 338, 339. The incident angle of each color light on the polarization separation films 337, 338, 339 is 45 °
The polarization separation film transmits P-polarized light and reflects S-polarized light with respect to the polarization separation film surface. The reflected S-polarized light of green, red, and blue light enters the reflective liquid crystal panels 340, 341 and 342, respectively. The reflection type liquid crystal panels 340, 341 and 342 are of an active matrix type and include a liquid crystal layer and a reflection film. As the liquid crystal, a 45-degree twisted nematic liquid crystal is used. In a reflective liquid crystal panel, the birefringence of liquid crystal changes when a voltage is applied in accordance with a video signal. The light incident on the driven pixels of the reflective liquid crystal panel passes through the liquid crystal, is reflected by the reflective film, and changes the polarization state of the light from S-polarized light to P-polarized light due to birefringence in the process of transmitting the liquid crystal again. And emits. The green P-polarized color light emitted from the reflective liquid crystal panel 340 passes through the polarization splitting prism 334 and then enters the dichroic prism 345 serving as a color combining unit. The red and blue P-polarized lights emitted from the reflection type liquid crystal panels 341 and 342 are respectively separated by the polarization separation prism 3.
35, 336, and the half-wave plate 347,
After the polarization direction is rotated by 348 and converted into S-polarized light, the dichroic prism 345 as a color combining means
Incident on. Green by the dichroic prism 345,
The red and blue light components are combined and enlarged and projected on a screen by a projection lens 346.

On the other hand, reflective liquid crystal panels 340 and 34
The S-polarized light that has entered the undriven pixels 1 and 342 and has been emitted without changing the polarization state is
The light is reflected at 34, 335, and 336, and returns to the illumination optical unit 309 side.

In this manner, the optical image formed as a change in the polarization state of light in the reflection type liquid crystal panel is enlarged and projected on a screen (not shown), and a full-color projected image is formed.

The second projection display device uses an inexpensive and small-sized illumination optical device 309 capable of efficiently converting natural light into one-way polarized light and providing uniform illumination, and a reflective liquid crystal panel. Therefore, a projection display device having a relatively small size, an ultra-high resolution, and a high brightness can be configured.

As described above, the second projection type display device has a high efficiency of polarization separation even at a relatively large incident angle, and has a small wire grid polarization separation element 302 excellent in heat resistance and light resistance. And a half-wave plate 307 arranged near the second lens array plate 306 having a small incident angle of incident light and rotating the polarization direction. Equipment cost reduction,
There is a very great effect that the light use efficiency can be improved while the size is reduced, and the brightness of the projection display device can be increased.

FIG. 11 shows an example in which the illumination optical device 309 having the same configuration as the first illumination optical device shown in FIG. 1 is used. Any of the illumination optical devices described in the first to third embodiments may be used.

In Embodiments 4 and 5, an example in which three liquid crystal panels using polarized light are used as the image forming means has been described. However, a projection type display apparatus using one liquid crystal panel may be used. Good.

For example, a color filter (color separation optical means) for separating white light into red, green, and blue light is arranged on the incident side of one liquid crystal panel, and a color image formed on the liquid crystal panel is formed. May be enlarged and projected.

Alternatively, on the incident side of one liquid crystal panel,
A microlens array substrate having a large number of microscopic microlenses corresponding to pixels of one unit of red, green, and blue of a liquid crystal panel is arranged, and a dichroic mirror as shown in FIGS. 10 and 11 is used. By making each color light of red, green, and blue from the color separation optical means incident on the microlens array substrate at a different angle, a color image may be formed on the liquid crystal panel, and this may be enlarged and projected. A method of forming a color image with one liquid crystal panel using a microlens array is described in, for example, Japanese Patent Application Laid-Open No. 4-60538.

Further, the projection type display device of the present invention can be used in addition to the type of observing the screen from the same side as the light projection side.
Any projection display device that projects the rear surface on a transmission screen and observes the screen from the side opposite to the projection side may be used.

[0114]

As described above, according to the present invention, the wire grid polarization separation element disposed near the position where the light from the light source converges, and the position where the light polarized and separated at a relatively small incident angle is incident , A low-cost, small and very efficient illumination optical device and a bright projection display device can be configured.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first illumination optical device of the present invention.

FIG. 2 is a perspective view showing a configuration of a wire grid polarization splitting element.

FIG. 3 is a diagram showing polarization separation characteristics of a wire grid polarization separation element.

FIG. 4 is a schematic configuration diagram of a first light collecting means using a parabolic mirror and a lens;

FIG. 5 is a schematic configuration diagram showing another configuration example of the first illumination optical device of the present invention.

FIG. 6 is a schematic configuration diagram of a second illumination optical device of the present invention.

FIG. 7 is a diagram showing a relationship between a convergence position of two polarization-separated polarized lights and light use efficiency.

FIG. 8 is a schematic configuration diagram showing another configuration example of the second illumination optical device of the present invention.

FIG. 9 is a schematic configuration diagram of a third illumination optical device of the present invention.

FIG. 10 is a schematic configuration diagram of a first projection display device of the present invention.

FIG. 11 is a schematic configuration diagram of a second projection display device of the present invention.

FIG. 12 is a schematic configuration diagram of a conventional projection display device.

[Explanation of symbols]

30, 70, 100, 130, 160, 200, 300
Lamps 31, 71, 101, 131, 161, 201, 301
Ellipsoidal mirror 32, 72, 102, 132, 162, 202, 303
Wire grid polarization separation element 33, 73, 203, 303, 210, 223, 22
4, 225, 310, 333 Reflecting mirror 103, 133 Reflecting prism 163 Back reflecting flat glass 34, 74, 104, 134, 164, 204, 304
Aspherical lenses 35, 75, 105, 135, 165, 205, 305
First lens array plate 36, 76, 106, 136, 166, 206, 306
Second lens array plate 37, 77, 107, 137, 167, 207, 30
7, 347, 348 1/2 wavelength plate 38, 78, 108, 138, 168, 208, 308
Superimposing lenses 39, 79, 109, 139, 169, 209, 309
Illumination optical device 40, 80, 110, 140, 170, 228, 22 of the present invention
9, 230 Field lens 41, 81, 111, 141, 171, 234, 23
5, 236 Liquid crystal panel 42 Glass substrate 43 Metal lattice 44 Grid periodic direction 45 Natural light 50, 91, 120, 151, 181, 211, 311
Optical axes 51, 90, 121, 150, 180, 212, 312 of P-polarized light transmitted through the polarization splitting element
Optical axes 52, 92, 122, 152, 182, 213, 313 of S-polarized light reflected by the polarization splitting element
Optical axes 53, 93, 123, 153, 183, 214, 314 of the illumination optical device
Aspects of rays converged and converged by an ellipsoidal mirror 54, 94, 124, 154, 184 Aspects of some rays in which polarized light is illuminated on a liquid crystal panel 60 Parabolic mirror 61 Condenser lens 220 Red Transmitting dichroic mirrors 221, 331 Green reflecting dichroic mirrors 222, 332 Color separation optical means 226, 227 Relay lenses 231, 232, 233 Polarizing plates 237, 238, 239 on the input side Polarizing plates 241, 344, 330 on the output side Reflection dichroic mirror 240, 343 Red reflection dichroic mirror 242, 345 Dichroic prism 243, 346 Projection lens 334, 335, 336 Polarization separation prism 337, 338, 339 Polarization separation film 340, 341, 342 Reflective liquid crystal panel

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03B 21/00 G03B 21/00 E 33/12 33/12 F term (Reference) 2H049 BA04 BA06 BB03 BB61 2H088 EA14 EA15 EA16 EA18 EA19 HA06 HA13 HA20 HA24 HA28 2H091 FA05X FA08 FA10 FA19 FA21 FA26 FA41Z FC29 FC30 FD07 FD12 FD22 FD24 LA03 LA04 LA15 MA07 2H099 AA12 BA09 CA11 CA17

Claims (20)

[Claims] 1. An illumination optical device for illuminating an image forming means for forming an image, comprising: a light source for emitting natural light; a first light collecting means for collecting and converging light emitted from the light source; Light from the first light condensing means is incident thereon, and is separated into first and second polarized lights whose polarization directions are orthogonal to each other, and one of them is reflected and the other is transmitted. And the second polarized light from the polarized light separating means enters,
A reflecting means for reflecting light in a predetermined direction; a first polarized light from the polarized light separating means; and a second polarized light reflected by the reflecting means are incident, converted into substantially parallel lights, and emitted. A second condensing means for causing the first and second polarized light beams from the second condensing means to enter, and split into a plurality of light fluxes and emitted therefrom, respectively. A first lens array plate comprising: a plurality of lens elements to which a plurality of light beams of the first polarized light and a plurality of light beams of the second polarized light from the first lens array plate respectively enter A second lens array plate provided with the first polarized light and the second polarized light from the second lens array plate, and the first polarized light and the second polarized light By rotating at least one of the polarization directions, the polarization directions of both are substantially reduced. A polarization rotating unit for matching the light, wherein the polarization separating unit is disposed near a convergence position of the light by the first condensing unit, and forms the metal in a stripe shape with a period sufficiently smaller than the wavelength of visible light. A wire grid polarization splitting element for splitting incident light by a metal grid, wherein the polarization rotating unit converges the plurality of light fluxes from the first lens array plate onto the second lens array plate, respectively. An illumination optical device which is arranged near a position. 2. An illumination optical device for illuminating an image forming means for forming an image, comprising: a light source for emitting natural light; a first light collecting means for collecting and converging light emitted from the light source; Light from the first light condensing means is incident thereon, and is separated into first and second polarized lights whose polarization directions are orthogonal to each other, and one of them is reflected and the other is transmitted. And the second polarized light from the polarized light separating means enters,
A reflecting means for reflecting light in a predetermined direction; a first polarized light from the polarized light separating means; and a second polarized light reflected by the reflecting means are incident, converted into substantially parallel lights, and emitted. A second condensing means for causing the first and second polarized light beams from the second condensing means to enter, and split into a plurality of light fluxes and emitted therefrom, respectively. A first lens array plate comprising: a plurality of lens elements to which a plurality of light beams of the first polarized light and a plurality of light beams of the second polarized light from the first lens array plate respectively enter A second lens array plate provided with the first polarized light and the second polarized light from the second lens array plate, and the first polarized light and the second polarized light By rotating at least one of the polarization directions, the polarization directions of both are substantially reduced. A polarization rotating unit for matching the light, wherein the polarization separating unit is disposed near a convergence position of the light by the first condensing unit, and forms the metal in a stripe shape with a period sufficiently smaller than the wavelength of visible light. A wire grid polarization splitting element for splitting incident light by a metal grid, wherein the polarization rotating unit converges the plurality of light fluxes from the first lens array plate onto the second lens array plate, respectively. An illumination optical device, which is arranged near a position, wherein the reflection means comprises a reflection prism, and wherein the second polarized light passes through a medium of the reflection prism. 3. An illumination optical device for illuminating an image forming means for forming an image, comprising: a light source for radiating natural light; a first light condensing means for condensing and converging light emitted from the light source; The light from the first condensing means enters, is separated into a first polarized light and a second polarized light whose polarization directions are orthogonal to each other, reflects the first polarized light, and Polarized light separating means for transmitting polarized light, and the second polarized light from the polarized light separating means is incident,
A reflecting means for reflecting light in a predetermined direction; a first polarized light from the polarized light separating means; and a second polarized light reflected by the reflecting means are incident, converted into substantially parallel lights, and emitted. A second condensing means for causing the first and second polarized light beams from the second condensing means to enter, and split into a plurality of light fluxes and emitted therefrom, respectively. A first lens array plate comprising: a plurality of lens elements to which a plurality of light beams of the first polarized light and a plurality of light beams of the second polarized light from the first lens array plate respectively enter A second lens array plate provided with the first polarized light and the second polarized light from the second lens array plate, and the first polarized light and the second polarized light By rotating at least one of the polarization directions, the polarization directions of both are substantially reduced. A polarization rotating unit for matching the light, wherein the polarization separating unit is arranged near a position where light is converged by the first condensing unit, and forms a metal in a striped pattern with a period sufficiently smaller than the wavelength of visible light. And a polarization rotator that polarizes and separates incident light by using a metal grating, wherein the polarization rotator converges the plurality of light beams from the first lens array plate on the second lens array plate. The reflection means is arranged in the vicinity of a position, and the reflection means comprises a back surface reflection mirror in which a reflection film is formed on one surface of a parallel plate glass, and the back surface reflection mirror is formed by a wire on a surface on which the reflection surface is not formed. An illumination optical device, which is in close contact with a grid polarization separation element. 4. The illumination optical device according to claim 1, wherein said first light-collecting means comprises an elliptical reflecting mirror. 5. The illumination optical device according to claim 1, wherein said first condensing means comprises a parabolic mirror and a lens. 6. The metal grid of the wire grid polarization splitting element has a period of 150 nm or less.
The illumination optical device according to any one of the above. 7. The height of the metal grid of the wire grid polarization splitting device is 200 nm or less.
The illumination optical device according to any one of the above. 8. The illumination optical device according to claim 1, wherein the metal of the wire grid polarization splitting element is aluminum. 9. The illumination optical device according to claim 1, wherein an aluminum film or a dielectric film is provided on a reflection surface of said reflection means. 10. The illumination optical device according to claim 1, wherein said second light condensing means comprises one aspherical lens for reducing spherical aberration. 11. The illumination optical device according to claim 10, wherein the aspheric lens is manufactured by molding. 12. The illumination optical device according to claim 10, wherein said aspherical lens is made of resin. 13. The illumination optical device according to claim 1, wherein said polarization rotating means is a half-wave plate made of a stretched resin film. 14. The illumination optical device according to claim 1, wherein said polarization rotating means is a half-wave plate formed of a thin film. 15. An illumination optical unit including a light source that emits white light, a color separation optical unit that separates white light from the light source into color light components of blue, green, and red, and a color separation optical unit. A projection type display device comprising: an image forming unit that receives each color light, and forms an optical image according to a video signal; and a projection lens that projects an optical image formed on the image forming unit onto a screen. A projection display device, wherein the illumination optical unit is the illumination optical device according to any one of claims 1 to 14. 16. The image forming means is provided three in correspondence with blue, green, and red color lights, and further combines blue, green, and red emitted lights from the three image forming means. 16. The projection display device according to claim 15, further comprising a color combining optical unit that performs color synthesis. 17. The projection display according to claim 15, wherein each color light from said color separation optical means is incident on a common image forming means, and said projection lens projects a color image formed on said image forming means. apparatus. 18. The projection display according to claim 15, wherein the image forming means is a transmission type liquid crystal panel. 19. An illumination optical unit including a light source that emits white light, a color separation optical unit that separates white light from the light source into color light components of blue, green, and red, and a color separation optical unit. And three polarized light separating prisms that separate the incoming colored light into two polarized light beams whose polarization directions are orthogonal to each other. Light from the three polarized light separating prisms respectively enters and according to a video signal Three image forming means for forming an optical image, and light emitted from each of the three image forming means is transmitted after passing through each of the three polarization splitting prisms, and then enters, and a color for combining these three incident lights is provided. A projection display device comprising: a combining optical unit; and a projection lens configured to project an optical image formed on the image forming unit on a screen, wherein the illumination optical unit is a lighting device. A projection display device, which is the illumination optical device according to any of the above. 20. The projection display device according to claim 19, wherein each of said three image forming means is a reflective liquid crystal panel.