JP3372942B2 - Image projection device - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an image projection apparatus.

[0002]

2. Description of the Related Art FIG. 12 is a main part configuration diagram showing one conventional example of an image projection apparatus of this type.

This image projection apparatus comprises a light source 101, such as a halogen lamp and a metal halide lamp, which emits non-polarized light, a reflection mirror 102 which reflects a part of the non-polarized light emitted from the light source 101, and a light source 101. A heat ray cut filter 103 that absorbs or reflects heat rays of non-polarized light that is incident directly or via a reflection mirror 102, and a condenser lens 10 that converts the non-polarized light from which the heat rays have been removed into non-polarized parallel light.
4 and a polarizing plate 105 for converting unpolarized parallel light into linearly polarized light
And a liquid crystal light valve 107 that is an image generator that generates an image by modulating linearly polarized light according to a video signal, and of the linearly polarized light modulated by the liquid crystal light valve 107, only the component in the transmission axis direction. Polarizing plate 108 that transmits light
And a projection lens 110, which is a projection optical system that projects the linearly polarized light that has passed through the polarizing plate 108 onto a screen (not shown) to project the image.

FIG. 13 is a schematic view of the main part of another conventional image projection apparatus of this type.

In this image projection device, instead of the two polarizing plates 105 and 108 of the image projection device shown in FIG. 12, two polarization beam splitters 106 and 109 are arranged in front of and behind the liquid crystal light valve 107, respectively. is there.

In the image projection apparatus shown in FIGS. 12 and 13, of the unpolarized light emitted from the light source 101, only the linearly polarized light that has passed through the polarizing plate 105 or the polarizing beam splitter 106 is illuminated by the liquid crystal light valve 107. Therefore, there is a drawback that linearly polarized light that does not pass through the polarizing plate 105 or the polarizing beam splitter 106 becomes a loss and the light utilization efficiency becomes 50% or less.

As an image projection apparatus that solves this drawback,
There is one described in JP-A-61-90584 shown in FIG.

In this image projection apparatus, the condenser lens
The unpolarized parallel light emitted from 104 enters the polarization beam splitter 111, and the action surface (2
The P-polarized light L _P is transmitted as it is, and the S-polarized light L _S is reflected at right angles upward and is incident on the total reflection prism 112 by the vapor deposition film 111 _{a on} which the two right-angle prisms are bonded to each other on the inclined surface. The S-polarized light L _S is reflected to the right at a right angle by the total reflection prism 112, so that the S-polarized light L _P is transmitted in the same direction as the P-polarized light L _P transmitted through the polarization beam splitter 111.
Is emitted from. Here, the S polarized light L _S is linearly polarized light having a polarization plane parallel to the working surface 111 _a of the polarization beam splitter 111, and the P polarized light L _P is the S polarization component L _S.
It means linearly polarized light having a plane of polarization orthogonal to. A half-wave plate 113 is arranged on the emission side of the total reflection prism 112, and the S-polarized light L _S emitted from the total reflection prism 112 is
The polarization plane is 90 ° by transmitting through the half-wave plate 113.
It is rotated and converted into P-polarized light L _P ^* . Further, wedge-shaped lenses 114 and 115 for changing the optical path are arranged on the exit sides of the polarization beam splitter 111 and the half-wave plate 113, respectively, and the P-polarized light L _P and the 1 / P-polarized light transmitted through the polarization beam splitter 111 are The optical path of the P-polarized light L _P ^* converted by the two-wavelength plate 113 is changed, and the P-polarized light L _P ^* intersects at a point P ₀ on the incident side surface of the liquid crystal light valve 117 to be combined light.

Therefore, in this image projection apparatus, the S-polarized lights L _S and P separated by the polarization beam splitter 111 are used.
Since the liquid crystal light valve 117 can be illuminated by both of the polarized light L _P, the light utilization efficiency can be doubled as compared with the image projection device shown in FIGS. 12 and 13. As another prior art document mentioned above, there is Japanese Patent Laid-Open No. 63-121821.
No. 2 (Liquid crystal display device with improved light utilization efficiency), U.S. Pat. No. 2,748,659 (automobile headlight provided with a polarization conversion element), U.S. Pat. No. 2,810,324.
No. specification (high-efficiency polarization device).

[0010]

However, in the image projection apparatus described in Japanese Patent Laid-Open No. 61-90584, the P-polarized light L _P and the P-polarized light L _P ^* converted by the ½ wavelength plate 113 are used ^. 14 and the liquid crystal light valve 117 are incident on the liquid crystal light valve 117 at the angle θ shown in FIG. There is a drawback that it is necessary to make the distance considerably large and the incident angle small.

As a method for solving this drawback, FIG.
A parallel illumination method is considered in which the wedge lenses 114 and 115 are removed and the P-polarized light L _P and the P-polarized light L _P ^* converted by the half-wave plate 113 are incident on the liquid crystal light valve 117 while being parallel to each other. To be However, even if this parallel illumination system is applied to the image projection apparatus described in Japanese Patent Laid-Open No. 61-90584, unless the light source 111 is a perfect point light source or a line light source, non-polarized parallel light emitted from the condenser lens 104 is used. Is not perfect, the two P-polarized components L _P ,
L _P ^* is not perfectly parallel either. This is shown in Figure 1.
This will be described using 5.

Non-polarized light emitted from a light source 101 having a finite diameter φ is focused by a condenser lens 104 arranged at a distance L, but the light emitted from the condenser lens 104 is not a perfect parallel light. Angle 2ω (ω = tan ^-1
The non-parallel light has a spread in the range of {(φ / 2) / L}. Since the ray α of the non-parallel light is incident on the ½ wavelength plate 113 without being affected by the polarization beam splitter 111, the S polarized light and the P polarized light are both included from the ½ wavelength plate 113. Emit. Further, the light beam β becomes the S-polarized light L _S at the polarization beam splitter 111, but it is a total reflection prism.
After being reflected by 112, it is again reflected by the polarization beam splitter 111 and is emitted from the ½ wavelength plate 113 as P-polarized light L _P ^* from a completely different position as shown by the ray β ₁ .
As indicated by light ray β ₂ in FIG. 5, the light is absorbed at the interface of the half-wave plate 113 or is transmitted as it is, resulting in loss of light.

Therefore, the above-mentioned JP-A-61-905 is used.
Since the image projection device described in Japanese Patent Publication No. 84 has a problem when used in the parallel illumination system, the wedge lenses 114 and 115 are indispensable. However, considering the light incident angle characteristics of the liquid crystal light valve 117, FIG. The angle θ shown in can not be increased so much that the wedge lenses 114 and 115 and the liquid crystal light valve
Since it is not possible to reduce the distance from 117 to a certain value or more, it is difficult to reduce the size of the entire device and the light source 10
There is a drawback in that the illumination efficiency (light utilization rate) is reduced as the distance between 1 and the liquid crystal light valve 117 increases.

Further, the image projection apparatus described in the above-mentioned Japanese Patent Laid-Open No. 61-90584 has a polarization beam splitter 111.
Since the total reflection prism 112 and the like are required,
There is a drawback that the entire device is larger than that shown in FIG.

It is an object of the present invention to provide an image projection device capable of making a polarization conversion system compact.

[0016]

An image projection apparatus of the present invention comprises an illumination optical system, image forming means for forming image light using polarized light from the illumination optical system, and projection for projecting the image light. The illumination optical system includes a lens group in which a plurality of condensing lenses are arranged along a predetermined direction that traverses an optical path of light from a light source, and a plurality of units arranged in the predetermined direction. Then, each of the plurality of light fluxes arranged in the predetermined direction from the lens group is incident on a corresponding unit of the plurality of units, and the polarized light from the plurality of units of the polarizing element is used. An optical system for illuminating the image forming means, and the plurality of units of the polarizing element respectively divide the incident light into reflected light and transmitted light whose polarization directions are orthogonal to each other, and the reflected light and Reflect one of the transmitted light And a reflecting section directed substantially in the same direction as the other traveling direction, and a modulating section that changes the polarization direction of at least one of the reflected light and the transmitted light to match the polarization directions of the two, and further, It is characterized in that a light shielding portion is provided at a position corresponding to each of the reflecting portions of a plurality of units.

In the above case, the image forming means may include a liquid crystal display element and a polarizing plate provided separately from the liquid crystal display element on the light emitting side of the liquid crystal display element. Further, the illumination optical system may include a lamp as the light source and a concave mirror that reflects light from the lamp toward the polarizing element.

Further, in each of the units, both the modulation section and the division section may be provided on a prism which constitutes the unit.

Further, the lens group may include a fly-eye lens having lenses arranged in the predetermined direction or a lenticular lens having lenses arranged in the predetermined direction.

Further, the modulator is a crystal such as mica or quartz, a stretched polymer film, a low-molecular liquid crystal aligned with the molecular axes, a side-chain high-molecular liquid crystal, or a low-molecular liquid crystal in a polymer. You may comprise with the polymer liquid crystal which disperse | distributed.

Further, the illumination optical system has a plurality of dichroic mirrors for obtaining the polarized lights of the three colors of R, G and B, and the image forming means has the three colors of R, G and B. The projection optical system has three liquid crystal display devices that form image light of three colors of R, G, and B by polarized light.
The image lights of the three colors of G and B may be combined and projected.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a unit 20 of a plate-shaped polarizing element showing a first embodiment of the plate-shaped polarizing element used in the image forming apparatus of the present invention.

The unit 20 of the plate-shaped polarizing element of the present embodiment has a first incident side prism 21 ₁ having a triangular prism shape whose cross section is a right triangle, and inclined faces adjacent to both sides of the _first incident side prism 21 _1. First and second emission side prisms 22 ₁ and 22 ₂ having the same shape as the _first incidence side prism 21 ₁ arranged in contact with each other, and the first incidence side of the first emission side prism 22 ₁ . A second incident-side prism 21 ₂ having a shape half that of the first incident-side prism 21 ₁ , which is arranged on the opposite side of the prism 21 ₁ with their slopes in contact with each other;
The third incident-side prism 21 ₃ having the same shape as that of the second incident-side prism 21 ₂ is arranged on the opposite side of the first incident-side prism 21 ₁ of the outgoing-side prism 22 ₂ with the inclined surfaces thereof in contact with each other. And three incident side prisms 21 ₁ ~
21 ₃ and the two exit side prisms 22 ₁ and 22 ₂ are integrated to form a single parallel plate. Further, the contact surface between the first incident-side prism 21 ₁ and the first emitting-side prism 22 ₁ has a first 1/1 / th distance on the first incident-side prism 21 ₁ side.
The four-wave plate 23 ₁ is provided, and the first polarization separating film 24 ₁ is provided on the first exit side prism 22 ₁ side. Further, a second quarter wave plate 23 ₂ is provided on the first incident side prism 21 ₁ side on the contact surface between the _first incident side prism 21 ₁ and the second emission side prism 22 _2. Therefore, the second polarization separation film 24 ₂ is provided on the side of the second exit side prism 22 ₂ . Second incident side prism 2
The contact surface between 1 ₂ and the first exit-side prism 22 ₁ has the first
Are total reflection mirror 25 ₁ is formed, and the third incidence side prism 21 ₃ The contact surface with the second exit-side prism 22 _2, the second total reflection mirror 25 ₂ are formed. Here, the first and second polarization separation action films 24 ₁ , 24
₂ has a characteristic of reflecting S-polarized light having a polarization plane parallel to the film surface and transmitting P-polarized light having a polarization plane perpendicular to the film surface. In addition, the first and second quarter-wave plates 23 ₁ and 23 ₂ receive the first and second incident lights P ₁ and P _{2 respectively.}
As described above, it acts on the light incident at an incident angle of 45 °, and its axial direction is selected so as to convert the S-polarized light into circularly polarized light.

That is, in the unit 20 of the plate-shaped polarizing element of the present embodiment, the contact surface between the first incident side prism 21 ₁ and the first outgoing side prism 22 ₁ and the first incident side prism 21 ₁ and the _first incident side prism 21 ₁ . The contact surface of the _second output prism 22 ₂ with the output-side prism 22 ₂ has almost the same angle of inclination with respect to the non-polarized light (the first and second incident lights P ₁ and P ₂ ), and the reflected light from the one (the first and second The second S-polarized light L _S1 , L _S2 ) functions as a pair of split surfaces that face each other toward the other, and the first and second polarization splitting films 24 ₁ and 24 ₂ polarize the incident light into polarization planes. Reflected light (first and second S-polarized light L _S1 ,
L _S2 ) and transmitted light (first and second P-polarized light L _P1 ,
L _P2 ) and functions as a dividing unit. In addition, the first and second total reflection mirrors 25 ₁ and 25 ₂ are one of reflected light and transmitted light (first and second S-polarized light L _S1 and L _S2 ).
To the other (first and second P-polarized light L _P1 ,
L _P2 ) functions as a reflecting portion that is directed in almost the same direction as the traveling direction. Further, the first and second quarter-wave plates 23
₁ and 23 ₂ are at least one of reflected light and transmitted light (first
And the second S-polarized light L _S1 , L _S2 ) functions as a modulator that changes the polarization planes of the two and matches the polarization planes of the two.

Next, the unit 20 of the plate-shaped polarizing element of this embodiment
The operation of will be described.

The first incident light P ₁ having a random polarization plane, which is incident on the contact surface between the first incident side prism 21 ₁ and the first outgoing side prism 22 ₁ at an incident angle of 45 °.
Of the first P-polarized light L _P1 having a polarization plane perpendicular to the film surface after passing through the first quarter-wave plate 23 ₁ and then entering the first polarization separation film 24 ₁ . The first S-polarized light L _S1 transmitted through the _first polarization separation film 24 ₁ and having a polarization plane parallel to the film surface is reflected rightward to the right by the first polarization separation film 24 _1. As a result, the first P-polarized light L _P1 and the first S-polarized light L _S1 are split. First P-polarized light L
_P1 exits from the exit surface of the first exit-side prism 22 ₁ . On the other hand, the first S-polarized light L _S1 is converted into circularly polarized light by passing through the _first ¼ wavelength plate 23 ₁ ,
By being transmitted through the _second quarter-wave plate 23 ₂ , it is converted into the first converted P-polarized light L _P1 ^* having a polarization plane perpendicular to the film surface of the second polarization separation film 24 _2. To be done. The first converted P-polarized light L _P1 ^* is transmitted through the second polarization separation film 24 ₂ and then reflected upward by the second total reflection mirror 25 ₂ at a right angle to the second exit side prism. The first P-polarized light L _P1 is emitted from the emission surface of 22 _{2 in} the same direction as the traveling direction.

Further, the first incident side prism 21 ₁ and the second incident side prism 21 ₁
The second incident light P ₂ having a random polarization plane, which is incident on the contact surface with the exit side prism 22 ₂ at an incident angle of 45 °, is transmitted through the second quarter-wave plate 23 ₂ . Later second
The polarization separation enters the working film _{24. 2,} the second P-polarized light L _P2 is transmitted through the second polarization separation acting film 24 ₍₂₎ having a polarization plane perpendicular to the film surface, parallel with respect to the film plane The second S-polarized light L _S2 having a different polarization plane is reflected at a right angle to the left by the second polarization splitting film 24 ₂ , so that the second P-polarized light L _S2 .
It is split into _P2 and the second S-polarized light L _S2 . The second P-polarized light L _P2 is emitted from the emission surface of the second emission side prism 22 ₂ . On the other hand, the second S-polarized light L _S2 is converted into circularly polarized light by passing through the _second quarter-wave plate 23 _2, and then transmitted through the first quarter-wave plate 23 _1. The second converted P-polarized light L _P2 ^* having a polarization plane perpendicular to the film surface of the first polarization separation film 24 ₁ is converted. The second converted P-polarized light L _P2 ^* passes through the first polarization splitting film 24 ₁ and then the first total reflection mirror 25 ₁
Is reflected upward at a right angle by the first exit side prism 22
The second P-polarized light L _P2 is emitted from the emission surface of _{1 in} the same direction as the traveling direction.

Therefore, the unit 20 of the plate-shaped polarizing element of the present embodiment is the first incidence side prism 21 ₁ which is incident on the first incidence side prism 21 1.
And the second incident light P ₁ , P ₂ to the first and second P polarized light L _P1 , L _P2 and the first and second converted P polarized light L
_P1 ^*, to convert without loss and L _P2 ^*, can be emitted from the emission surface entirely.

Next, the unit 20 of the plate-shaped polarizing element of this embodiment
The material of each component will be described.

First, second and third incident side prisms 2
1 _{1 to} 21 ₃ and the first and second exit side prisms 22
₁ , 22 ₂ may be made of glass, plastic, or the like.
_In order to keep the separation function of ₁ and 24 ₂ optimal, it is preferable to use glass having a large degree of freedom in selecting the refractive index. It is also possible to use a combination of parallel flat plates without using a prism, but in this case, the transmittance of P-polarized light is inferior to that when a prism is used. The first and second quarter-wave plates 23 ₁ and 23 ₂ are crystalline ones such as mica and quartz,
Consists of a stretched polymer film, a low-molecular liquid crystal with a certain thickness, orientated with the molecular axes aligned in a certain direction, a side-chain polymer liquid crystal, or a low-molecular liquid crystal dispersed in a polymer. be able to. The first and second polarization splitting films 24 ₁ and 24 ₂ can be composed of known optical multilayer films. First
The second total reflection mirrors 25 ₁ and 25 ₂ may use aluminum vapor deposition mirrors, or the second and third incident side prisms 21 ₂ and 21 ₃ may be removed to remove the first and second emission mirrors. The slopes of the side prisms 22 ₁ and 22 ₂ on the side opposite to the first incident side prism 22 ₁ may be used as the air boundary surface.

As an example of the configuration of arranging a plurality of units 20 shown in FIG. 1 to form a plate-shaped polarizing element, as shown in FIG. 2, a plate-shaped polarizing element 4 is formed by arranging a plurality of units 20 in the lateral direction.
There is one. In addition, as another configuration example, as shown in FIG. 3, a plate-shaped polarizing element 41a configured by arranging a plurality of units 20 arranged side by side in the lateral direction and arranging a plurality of columns with a pitch shifted by half between adjacent columns is provided. is there. In the plate-shaped polarization elements 41 and 41a shown in FIGS. 2 and 3, the incident-side prism (FIG.
The second incident-side prism 21 ₂ and the third incident-side prism 21 ₃ ) may be integrally configured.

FIG. 4 is a block diagram of a unit 20a of a plate-shaped polarizing element showing a second embodiment of the plate-shaped polarizing element used in the image forming apparatus of the present invention.

The unit 20a of the plate-shaped polarizing element of this embodiment differs from the unit 20 of the plate-shaped polarizing element shown in FIG.
And instead of the second quarter wave plates 23 ₁ and 23 ₂ , 1
Of the contact surfaces of the first entrance-side prism 21 ₁ and the first exit-side prism 22 ₁ and the contact surfaces of the first entrance-side prism 21 ₁ and the second exit-side prism 22 _2. It is provided in the middle.

In the unit 20a of the plate-shaped polarizing element of this embodiment, the first incident light P ₁ is the first P-polarized light L _{P1 which} is transmitted through the first polarization separation film 24 ₁ and The S-polarized light L _S1 is reflected at a right angle to the right by the first polarization separation action film 24 ₁ , so that the first P-polarized light L _P1 and the first S-polarized light L _S1.
Is divided into and The first P-polarized light L _P1 is emitted from the emission surface of the first emission-side prism 22 ₁ . On the other hand, the first S-polarized light L _S1 is transmitted through the half-wave plate 26 so that the polarization plane is rotated by 90 ° and the first converted P-polarized light L _{P1 is obtained.}
Converted to ^* . The first converted P-polarized light L _P1 ^* is the second
Of after passing through the polarization separation action film 24 _2, it is reflected at a right angle upwardly at the second total reflection mirror 25 _2, the second exit surface of the exit-side prism 22 ₂ of the first P-polarized light L _P1 Emit in the same direction as the traveling direction. In addition, the second incident light P
₂ indicates that the second P-polarized light L _P2 is the second polarization separation action film 24 ₂
And the second S-polarized light L _S2 is reflected by the second polarization separation film 24 ₂ at the right angle to the left, and thus the second P-polarized light L _S2 is transmitted.
It is split into polarized light L _P2 and second S-polarized light L _S2 . Second
The P-polarized light L _P2 is emitted from the emission surface of the second emission-side prism 22 ₂ . On the other hand, the second S-polarized light L _S2 is converted to the second converted P-polarized light L _P2 ^* by rotating the polarization plane by 90 ° by passing through the ½ wavelength plate 26. Second
Of the converted P-polarized light L _P2 ^* of the first polarization separation film 2
After passing through 4 ₁ , it is reflected at a right angle upward by the first total reflection mirror 25 ₁ , and is in the same direction as the traveling direction of the second P-polarized light L _P2 from the exit surface of the _first exit-side prism 22 _1. Emit to. Therefore, the unit 20 of the plate-shaped polarizing element of this embodiment is
a also the incident on the first incident-side prism 21 ₁ 1
And the second incident light P ₁ , P ₂ to the first and second P polarized light L _P1 , L _P2 and the first and second converted P polarized light L
_P1 ^*, to convert without loss and L _P2 ^*, can be emitted from the emission surface entirely. The half-wave plate 26 is
Where the contact surface between the incident-side prism 21 ₁ and the first exit-side prism 22 ₁ and the contact surface between the first incident-side prism 21 ₁ and the second exit-side prism 22 ₂ are provided. Good.

FIG. 5 is a constitutional view of a unit 30 of a plate-shaped polarizing element showing a third embodiment of the plate-shaped polarizing element used in the image forming apparatus of the present invention.

In the unit 30 of the plate-shaped polarizing element of this embodiment, the splitting portion (polarization splitting film 34) is obliquely arranged with respect to the unpolarized light (incident light P), and the reflecting portion (total reflection film 35) is provided. The half-wave plate 36, which is arranged in parallel to the division portion and serves as a modulation portion, has an optical path of the reflected light (S-polarized light L _S ), particularly the reflection portion (total reflection film 3
5) is arranged in the optical path of the reflected light (S-polarized light L _S ) reflected in 5).

That is, the unit 30 of the plate-shaped polarizing element of this embodiment is the first glass member 31 whose cross section is a parallelogram.
_1, are arranged by contacting the slope with each other to the first glass member 31 ₁ on both sides, second and third cross-section of a right triangle
Of the glass member 31 _2, made of 31 ₃ which, three glass members 31 ₁ to 31 ₃ constitute a single parallel plate together. Further, a total reflection film 35 is provided on the contact surface between the _first glass member 31 ₁ and the second glass member 31 _2, and the first glass member 31 ₁ and the third glass member 31 _{3 are provided.}
A polarization separation film 34 is provided on the contact surface with. Further, on the emission surface of the first glass member 31 ₁ (the surface opposite to the surface on which the incident light P enters), the half-wave plate 36
Is provided. Here, the polarization splitting film 34 has a property of reflecting S-polarized light having a polarization plane parallel to the film surface and transmitting P-polarized light having a polarization plane perpendicular to the film surface. Further, the half-wave plate 36 acts on the light incident at an incident angle of 90 °. Therefore, in the unit 30 of the plate-shaped polarizing element of the present embodiment, the polarization splitting action film 34 reflects the incident light (S-polarized light L _S ) and transmitted light (P-polarized light L _P ) whose polarization planes are orthogonal to each other. It functions as a division unit that divides into. Further, the total reflection film 35 functions as a reflection portion that reflects one of the reflected light and the transmitted light (S-polarized light L _S ) and directs the light in the substantially same direction as the traveling direction of the other (P-polarized light L _P ). Further, the half-wave plate 36 functions as a modulator that changes the polarization plane of at least one of the reflected light and the transmitted light (S-polarized light L _S ) to match the polarization planes of the two.

Next, the unit 30 of the plate-shaped polarizing element of this embodiment
The operation of will be described.

Incident light P having a random polarization plane, which is incident on the film surface of the polarization separating film 34 at an incident angle of 45 °, is P-polarized light L _P having a polarization plane perpendicular to the film surface.
Is transmitted through the polarization splitting film 34, and the S-polarized light L _S having a polarization plane parallel to the film surface is reflected by the polarization splitting film 34 at a right angle to the left, so that the P-polarized light L _P is obtained. It is split into S-polarized light L _S. P-polarized light L _P is the exit surface of the third glass member 31 ₃ (surface opposite to the surface where the incident light P is incident)
Exit from. On the other hand, the S-polarized light L _S is reflected upward at a right angle by the total reflection film 35, and is emitted from the emission surface of the _second glass member 31 _{2 in} the same direction as the traveling direction of the P-polarized light L _P. By passing through the wave plate 36, the polarization plane becomes 9
It is rotated by 0 ° and converted into P-polarized light L _P ^* . Therefore, the unit 30 of the plate-shaped polarizing element of this embodiment converts the incident light P incident on the _first glass member 31 ₁ into the P-polarized light L _P and the converted P-polarized light L _P ^* without loss. Then, the light can be emitted from the entire emission surface.

As an example of the configuration of arranging a plurality of the units 30 shown in FIG. 5 to form a plate-shaped polarizing element, the unit 2 shown in FIG.
Similar to 0, there is a configuration example shown in FIGS. 2 and 3. Here, since the unit 30 shown in FIG. 5 can be formed by arranging a plurality of glass members each having a parallelogrammic cross section when forming a plate-shaped polarizing element, the unit 30 has better workability than the unit 20 shown in FIG. It has the effect of being That is, the unit 20 is a glass plate provided with the polarization splitting film 34 on one surface and a total reflection film 35.
Easily by alternately laminating (for example, aluminum vapor deposition film) a glass plate provided on one side, cutting at a cross section of 45 °, optically polishing the cut surface, and then bonding the half-wave plate 36. Can be created.

FIG. 6 is a constitutional view of a unit 30a of a plate-shaped polarizing element showing a fourth embodiment of the plate-shaped polarizing element used in the image forming apparatus of the present invention.

The unit 30a of the plate-shaped polarizing element of this embodiment is different from the unit 30 of the plate-shaped polarizing element shown in FIG.
That is, the two-wave plate 36 is disposed between the polarization splitting film 34 (dividing portion) and the total reflection film 35 (reflecting portion).

In the unit 30a of the plate-shaped polarizing element of this embodiment, as for the incident light P, the P-polarized light L _P is transmitted through the polarization splitting action film 34 and the S-polarized light L _S is leftward at the polarization splitting action film 34. Reflected at right angles to the P-polarized light L _P and the S-polarized light L _S
Is divided into and The P-polarized light L _P is emitted from the third glass member 31 ₃
Is emitted from the emission surface of. On the other hand, the S-polarized light L _S is transmitted through the half-wave plate 36 so that the plane of polarization is rotated by 90 ° and converted into P-polarized light L _P ^* , and then reflected at a right angle upward by the total reflection film 35. , P-polarized light L _P is emitted from the emission surface of the second glass member 31 _{2 in} the same direction as the traveling direction. Therefore, the unit 30a of the plate-shaped polarizing element of this embodiment is the first
The incident light P incident on the glass member 31 ₁ can be converted into the P-polarized light L _P and the converted P-polarized light L _P ^* without any loss and can be emitted from the entire emission surface.

FIG. 7 is a constitutional view of a unit 30b of a plate-shaped polarizing element showing a fifth embodiment of the plate-shaped polarizing element used in the image forming apparatus of the present invention.

The unit 30b of the plate-shaped polarizing element of this embodiment is different from the unit 30 of the plate-shaped polarizing element shown in FIG.
That is, the two-wave plate 36 is bonded to the emission surface of the _third glass member 31 ₃ which is the optical path of the transmitted light (P-polarized light L _P ).

In the unit 30b of the plate-shaped polarizing element of this embodiment, as for the incident light P, the P-polarized light L _P is transmitted through the polarization splitting action film 34 and the S-polarized light L _S is leftward at the polarization splitting action film 34. Reflected at right angles to the P-polarized light L _P and the S-polarized light L _S
Is divided into and The P-polarized light L _P is emitted from the third glass member 31 ₃
After the light is emitted from the emission surface of, the polarization plane is rotated by 90 ° by passing through the half-wave plate 36, converted into S-polarized light L _S ^* , and emitted. On the other hand, the S-polarized light L _S is reflected by the total reflection film 3
5, the light is reflected upward at a right angle and is emitted from the emission surface of the _second glass member 31 _{2 in} the same direction as the traveling direction of the converted S-polarized light L _S. Therefore, in the unit 30b of the plate-shaped polarizing element of the present embodiment, the incident light P incident on the _first glass member 31 ₁ is converted into the S-polarized light L _S and the converted S-polarized light L _S ^*.
The light can be converted into light without loss and emitted from the entire emission surface.

FIG. 8 is a perspective view showing a part of the first embodiment of the polarization conversion unit used in the image forming apparatus of the present invention.

The polarization conversion unit 40 of this embodiment is shown in FIG.
And the double-sided lenticular lens 42, which is provided on the incident side of the plate-shaped polarization element 41 and is a conversion unit that converts unpolarized light into unpolarized light in a fence pattern.
Consists of. Here, the plate-shaped polarizing element 41 is arranged so as to be substantially orthogonal to the optical axis of the fence-shaped pattern of non-polarized light emitted from the double-sided lenticular lens 42, and transmits the fence-shaped pattern of non-polarized light to be almost dense. It converts into polarized light. In addition, as shown in FIG. 9, the surface of the double-sided lenticular lens 42 on the incident side of the incident lights P _{1 to} P ₃ (non-polarized light) has a function of converging the incident lights P _{1 to} P ₃ and having a positive power. Focusing surfaces 43 ₁ to 43 ₃ formed of lenses are provided at the same pitch as each unit 20 _{1 to} 20 _{3 of} the plate-shaped polarizing element 41. In addition, the incident light P of the double-sided lenticular lens 42
The surface of the exit side of the ₁ to P _3, to diverge the incident light P ₁ to P ₃ which is focused with the effect of the parallel light, divergent working surfaces 44 _{1-44 3} consisting of a negative power lens, the Unit 20 _{1 to} 20 ₃
The first entrance-side prism 21 ₁ (see FIG. 1) is provided so as to face each other. Further, each divergent action surface 44
Between _{1-44 3,} the nonoperating surface 45 _1, 45 ₂ which is a plan provided.

Therefore, the double-sided lenticular lens 4
By the incident light P ₁ to P ₃ coming incident perpendicularly to the plane of incidence of 2 which is focused by the focusing action surface 43 _{1-43 3,} as shown in FIG. 9, the nonoperating surface 45 _1, 45 ₂ Does not enter the divergent surface 44 ₁ -44 ₃ and then enters the divergent surface 44 ₁
The light emitted from the double-sided lenticular lens 42 becomes a fence-shaped non-polarized light because the light is collimated and emitted at ˜44 ₃ . The non-polarized light of this fence-shaped pattern is converted into polarized light by the plate-shaped polarizing element 41, and then each unit 20 _{1 to} 20 ₃
The light is emitted from the entire emission surface of. The divergent surface 44 ₁
To 44 the absolute value focusing action face of the _third focal length 43 _{1-43 3}
By setting the focal length to half, the luminous flux width of the non-polarized light in the fence-shaped pattern emitted from the double-sided lenticular lens 42 can be half the pitch of the focusing surfaces 43 ₁ to 43 ₃ . Further, by providing an absorbing film on the non-acting surfaces 45 ₁ and 45 ₂ , it is possible to reduce adverse effects due to diffused reflection and the like.

The polarization conversion unit 40 of this embodiment has the following advantages.

(1) Since the incident lights P _{1 to} P ₃ are converted by the double-sided lenticular lens 42 into non-polarized light in the form of a fence and are made incident on the respective units 20 _{1 to} 20 ₃ of the plate-shaped polarizing element 41,
The size of each unit 20 _{1 to} 20 ₃ can be reduced. Further, in order to further reduce the size of each unit 20 _{1 to} 20 ₃ of the plate-shaped polarizing element 41, the pitch of the focusing action surfaces 43 ₁ to 43 ₃ of the double-sided lenticular lens 42 is reduced to divide the number of fence-shaped patterns. Should be increased.

(2) Even if the light source has a finite diameter, the incident light beams P _{1 to} P ₃ are each unit 20 of the plate-like polarizing element 41.
_{1 to} 20 ₃ of the first and second polarization separation action films 24 ₁ and 4
5 ₂ Always for entering the can improve the degree of polarization of the disadvantages can be eliminated, the light use efficiency and the emitted light in the conventional image projection apparatus shown in FIG. 14. In particular, since it is relatively easy for the first and second polarization separation action films 24 ₁ and 24 ₂ to make the reflectance for S-polarized light 100%, it is possible to keep the polarization degree of the emitted light high. .

(3) Each unit 20 _{1 of the} plate-shaped polarizing element 41
The first, second and third entrance side prisms 21 _{1 to} 21 ₃ and the first and second exit side prisms 22 ₁ and 22 ₂ which are the components of 20 ₃ have the same shape and size. Therefore, it is possible to reduce the number of types of parts in manufacturing, and to reduce the cost. In particular, since it is possible to reduce the types of prisms that occupy a large proportion in terms of cost, the effect of cost reduction is extremely large.

As the double-sided lenticular lens 42, an acrylic plate extruded or compression molded can be used in consideration of ease of molding and optical characteristics such as transmittance. However, particularly when heat resistance is required, a compression molded product made of a glass member or a polished molded product is preferable.
Further, the double-sided lenticular lens 42 may be integrally formed or a single-sided lenticular lens may be attached. When the light source has a finite diameter, the fence-shaped pattern is obtained by setting the absolute value of the focal length of the divergent action surfaces 44 _{1 to} 44 ₃ to be half the focal length of the focusing action surfaces 43 ₁ to 43 _3. The ratio of the non-polarized light beam existence region to the non-light beam existence region can be set to 1: 1.

The polarization conversion unit 40 of this embodiment is shown in FIG.
The plate-shaped polarizing element 41 and the double-sided lenticular lens 42 shown in FIG. 4 are used, but the plate-shaped polarizing element and the double-sided lenticular lens composed of the units 20a, 30, 30a, and 30b shown in FIGS. It may be configured by using.

Next, a second embodiment of the polarization conversion unit used in the image forming apparatus of the present invention will be described.

The polarization conversion unit of this embodiment converts the non-polarized light, which is provided on the plate-shaped polarizing element 41a shown in FIG. 3 and the incident side of the plate-shaped polarizing element 41a, into non-polarized light having a lattice pattern. And a double-sided fly-eye lens which is a conversion means for In the polarization conversion unit of the present embodiment, after the incident light is split in the vertical and horizontal directions by the double-sided fly-eye lens, it is applied to the first incident-side prism 21 ₁ of each unit 20 _{1 to} 20 ₅ of the plate-shaped polarizing element 41a. Make it incident. Note that, also in this embodiment, the units 20a, 30, shown in FIGS.
It may be configured by using a plate-shaped polarization element composed of 30a and 30b and a double-sided fly-eye lens.

FIG. 10 is a schematic block diagram showing the first embodiment of the image projection apparatus of the present invention.

The image projection apparatus of the present embodiment includes the polarization conversion unit 40 shown in FIG. 8 as an illumination optical system for converting parallel white light (non-polarized light) from the first condenser lens 64 into white linearly polarized light. The point of use is different from the image projection apparatus shown in FIG. In the image projection apparatus of the present embodiment, the second condenser that collects the white linearly polarized light from the polarization conversion unit 40 in the pupil of the projection lens 68 between the polarization conversion unit 40 and the liquid crystal light valve 66. A lens 65 is provided.

Therefore, the image projection apparatus of this embodiment is
Polarization conversion unit 40 which is the polarization conversion unit of the present invention
To illuminate the liquid crystal light valve 66 with the light source 6
The white light (non-polarized light) emitted from the light source 1 can be incident on the liquid crystal light valve 66 without loss, and the distance from the light source 61 to the liquid crystal light valve 66 can be shortened. Can be realized.

FIG. 11 is a schematic configuration diagram showing a second embodiment of the image projection apparatus of the present invention.

The image projection apparatus of this embodiment includes a light source 71 which emits non-polarized light (white light), a reflection mirror 72, a heat ray cut filter 73, a first condenser lens 74,
An illumination optical system that converts non-polarized light from the light source 71 into polarized light, an image generation unit that generates an image by modulating the polarized light according to a video signal, and a projection optical system that projects the image. Here, the illumination optical system decomposes white light, which is non-polarized light, into non-polarized light of red, green, and blue, a first dichroic mirror 81 for decomposition, a second dichroic mirror 82 for decomposition, and a disassembled dichroic mirror 82. Separation unit 40 _R , 40 _G , 40 _B having the same structure as the polarization conversion unit 40 shown in FIG. When,
Red condenser lens 75 _R , green condenser lens 7
It is composed of 5 _G and a blue condenser lens 75 _B. In addition, the image generating unit is composed of three liquid crystal light valves 76 _R for red, green liquid crystal light valve 76 _G and blue liquid crystal light valve 76 _B for generating red, green and blue images. Become. Furthermore, the projection optics
First combining dichroic mirror 84, combining reflecting mirror 85, and second combining dichroic mirror 86.
And a projection lens 78.

In the image projecting apparatus of this embodiment, the red non-polarized light P _R is reflected upward by the first separating dichroic mirror 81 at a right angle, and is transmitted through the first separating dichroic mirror 81. Of the non-polarized light P _G + P _B of the blue non-polarized light P _B is transmitted through the second dichroic mirror for decomposition 82, and the green non-polarized light P _G is perpendicular to the upper side of the second dichroic mirror for decomposition 82. The parallel white light P _R + P _G + P _B , which is non-polarized light and is emitted from the first condenser lens 74 by being reflected by
The unpolarized light P _R , P _G , P _B of each color of green and blue is decomposed.
The red non-polarized light P _R is reflected to the left at a right angle by the separation reflection mirror 83, and then the red polarization conversion unit 40.
_It is incident on _R and converted into red polarized light. In addition, the green non-polarized light P _G receives the second separation dichroic mirror 8
After being reflected by 2, the light enters the polarization conversion unit 40 _G for green and is converted into green polarized light. Further, the blue unpolarized light P _B is reflected by the second dichroic mirror 82 for decomposition.
After being transmitted, it is incident on the blue polarization conversion unit 40 _B and is converted into blue polarized light.

The red polarized light is converted into the red condenser lens 7
It is incident on the red liquid crystal light valve 76 _R via 5 _R ,
The polarization plane is rotated in accordance with the red component of the color video signal to be modulated, and becomes a light flux including both P-polarized light and S-polarized light. Further, the red polarizing plate 77 _R linearly polarizes the red image light R. Converted to ^* . Similarly,
The polarized light of green is converted into the green image light G ^* modulated according to the green component of the color video signal by the action of the liquid crystal light valve for green 76 _G and the polarizing plate for green 77 _G.
In addition, blue polarized light is emitted from the blue liquid crystal light valve 76 _B.
By the action of the blue polarizing plate 77 _B , the blue image light B ^* modulated according to the blue component of the color video signal is converted.

The red image light R ^* and the green image light G ^* are the first
After being combined by the combining dichroic mirror 84 and converted into yellow image light R ^* + G ^* , the light is incident on the second combining dichroic mirror 86. Also, the blue image light B
^{The *} is reflected upward by the combining reflection mirror 85 at a right angle, and then enters the second combining dichroic mirror 86. Then, the yellow image light R ^* + G ^* is transmitted through the second combining dichroic mirror 86, and the blue image light B ^* is reflected at a right angle to the left by the second combining dichroic mirror 86, whereby a yellow image is obtained. Light R ^* + G ^* and blue image light B ^*
And are combined and converted into white image light R ^* + G ^* + B ^* modulated according to the color video signal. White image light R ^*
+ G ^* + B ^* is enlarged and projected on a screen (not shown) by the projection lens 78, and a color image is projected on the screen.

The image projection apparatus of this embodiment has the following effects by having the polarization conversion unit for each of the non-polarized light P _R , P _G , P _B of each color of red, green and blue.

(1) Red polarization conversion unit 40 _R , green polarization conversion unit 40 _G and blue polarization conversion unit 4
Since it is difficult to reduce the wavelength dependence of the quarter-wave plate and the polarization splitting action film (see FIG. 1) used for each unit of 0 _B to zero, the parallel white light P _R which is unpolarized light + P _G +
Than the P _B and the incident light, Red, Green, unpolarized light P _R of the respective colors of blue, P _G, improved who was a P _B incident light utilization efficiency of light attained.

(2) Since the light source 71 generally has a finite diameter, the white light emitted from the light source 71 always has a finite divergence angle. When the beam diameter of light having a finite divergence angle is compressed by some optical system, the divergence angle increases in inverse proportion to the compression ratio of the beam diameter. Therefore, in the conventional image projection device shown in FIG. 14, since the distance between the polarization conversion unit and the liquid crystal light valve 117 is large, even if the beam diameter of light having a finite divergence angle is compressed, the divergence angle of the light is reduced. Due to the increase, the light collection efficiency on the liquid crystal light valve 117 is reduced. On the other hand, in the image projection apparatus of the present embodiment, since the thin plate-shaped polarization conversion unit is used, the polarization conversion unit can be installed close to the liquid crystal light valve, so that red, green, and blue unpolarized light is emitted. It is possible to prevent a decrease in the light collection efficiency on the liquid crystal light valve 117 due to an increase in the spread angle of P _R , P _G , and P _B.

Next, a third embodiment of the image projection apparatus of the present invention will be described.

The image projection apparatus of the present embodiment has a first separation dichroic mirror 81 and a second separation dichroic mirror 82 instead of the green polarization conversion unit 40 _G and the blue polarization conversion unit 40 _B. 11 is different from the image projection apparatus shown in FIG. 11 in that it has a cyan polarization conversion unit provided in a space (a common optical path of the green non-polarized light P _G and the blue non-polarized light P _B ).

When a plurality of polarization conversion units are used, each polarization conversion unit has an optically equivalent position (light traveling direction and amplitude) in terms of utilization efficiency of light emitted from the light source and suppression of occurrence of color unevenness. Since it is better to arrange each of them in an equivalent position), it is desirable to configure the image projection apparatus as shown in FIG. 11. However, in the case where the reduction of the number of parts is prioritized, the image of the present embodiment can be obtained. Even if the projector is configured like a projection device and the number of polarization conversion units is reduced, the light utilization efficiency can be improved as compared with the conventional image projection device, and the entire device can be made compact.

[0073] In the image projection apparatus shown in FIG. 11, as the polarization conversion unit 40 _R, 40 _G, 40 _B for the respective colors, the unit 20a shown in FIGS. 4 to 7, 30, 30a,
A configuration in which a plate-shaped polarizing element made of 30b and a double-sided lenticular lens are combined, or a configuration in which the plate-shaped polarizing element 41a shown in FIG. 3 and a double-sided fly-eye lens are combined may be used. Further, the configuration of the image projection apparatus of the present invention is not limited to the configuration shown in FIG. 11, and for example, as in Japanese Patent Laid-Open No. 62-59919, white light is converted into white light using each color filter. Disassembled into
In the image projection device that synthesizes each color light modulated by the liquid crystal light valve by the cube prism, the polarization conversion unit 40 shown in FIG. 8 may be arranged for each color filter. In addition, as described in JP-A-62-13911, the first
In the image projection device that decomposes white light into each color light with the cube prism and combines each color light modulated by the reflection type liquid crystal light valve with the second cube prism, on the emission surface of each color light of the first cube prism. The polarization conversion unit 40 shown in FIG. 8 may be arranged.

[0074]

As described above, according to the present invention,
In a compact system, non-polarized light emitted from a light source can be converted into polarized light to improve light utilization efficiency.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a unit 20 of a plate-shaped polarizing element showing a first embodiment of a plate-shaped polarizing element used in an image projection apparatus of the present invention.

FIG. 2 is a partial view showing a configuration example in which a plurality of units 20 shown in FIG. 1 are arranged to form a plate-shaped polarizing element.

FIG. 3 is a partial view showing another configuration example in which a plurality of units 20 shown in FIG. 1 are arranged to form a plate-shaped polarizing element.

FIG. 4 is a configuration diagram of a unit 20a of a plate-shaped polarizing element showing a second embodiment of the plate-shaped polarizing element used in the image projection device of the present invention.

FIG. 5 is a configuration diagram of a unit 30 of a plate-shaped polarizing element showing a third embodiment of the plate-shaped polarizing element used in the image projection device of the present invention.

FIG. 6 is a configuration diagram of a unit 30a of a plate-shaped polarization element showing a fourth example of the plate-shaped polarization element used in the image projection apparatus of the present invention.

FIG. 7 is a configuration diagram of a unit 30b of a plate-shaped polarizing element, which shows a fifth embodiment of the plate-shaped polarizing element used in the image projection device of the present invention.

FIG. 8 is a perspective view showing a part of a first embodiment of a polarization conversion unit used in the image projection device of the present invention.

9A and 9B are views for explaining the operation of the double-sided lenticular lens shown in FIG.

FIG. 10 is a schematic configuration diagram showing a first embodiment of the image projection apparatus of the present invention.

FIG. 11 is a schematic configuration diagram showing a second embodiment of the image projection apparatus of the present invention.

FIG. 12 is a main part configuration diagram showing an example of a conventional projection display device.

FIG. 13 is a main part configuration diagram showing another example of a conventional projection display device.

FIG. 14 is a main part configuration diagram showing a projection type display device described in JP-A-61-90584.

FIG. 15 is a diagram illustrating a problem when the parallel illumination method is applied to the projection display device of FIG.

[Explanation of symbols]

_{20,20 1 ~20 5, 20a, 30,30a} , 30b
Units 21 _{1 to} 21 ₃ Incident side prisms 22 ₁ and 22 ₂ Outgoing side prisms 23 ₁ and 23 ₂ 1/4 wave plates 24 ₁ , 24 ₂ and 34 Polarization separating action films 25 ₁ and 25 ₂ Total reflection mirrors 31 _{1 to} 31 ₃ glass member 35 total reflection film 36 1/2 wavelength plate 40 polarization conversion unit 40 _R polarization conversion unit for red 40 _G polarization conversion unit for green 40 _B polarization conversion unit for blue 41 plate-shaped polarization element 42 double-sided lenticular lens 43 ₁ ~ 43 ₃ Focusing action surface 44 _{1 to} 44 ₃ Divergence action surface 45 ₁ , 45 ₂ Non-action surface 61, 71 Light source 62, 72 Reflection mirror 63, 73 Heat ray cut filter 64, 74 First condenser lens 65 Second condenser lens 66 liquid crystal light valves 67 polarizer 68, 78 projection lens 75 _R red condenser lens 75 _G green condenser lens 75 _B for blue condenser lens 76 _R red Liquid crystal light valve 76 _G for green liquid crystal light valve 76 _B for blue liquid crystal light valves 77 _R for red polarizing plate 77 _G for green polarizer 77 _B for blue polarizing plate 81 first decomposition dichroic mirror 82 second cracking dichroic Mirror 83 Decomposing reflection mirror 84 First combining dichroic mirror 85 Combining reflecting mirror 86 Second combining dichroic mirror P, P ₁ , P ₂ , P ₃ Incident light L _P , L _P1 , L _P2 P polarized light L _S , L _S1 , L _S2 S-polarized light L _P ^* , L _P1 ^* , L _P2 ^* converted P-polarized light L _S ^* , L _S1 ^* , L _S2 ^* converted S-polarized light P _R + P _G + P _B parallel white light P _R red unpolarized light P _G green unpolarized light P _B blue unpolarized light R ^* red image light G ^* green image light B ^* blue image light R ^* + G ^* yellow image light R ^* + G ^* + B ^* White image light

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuki Kimura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Junko Shin Yoshiki 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Within the corporation (56) Reference JP-A-63-121821 (JP, A) US patent 2748659 (US, A) US patent 2810324 (US, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) ) G02B 27/28 G02B 5/30 G03B 21/00

Claims (7)

(57) [Claims] 1. An illumination optical system, an image forming unit that forms image light using polarized light from the illumination optical system, and a projection optical system that projects the image light, the illumination optical system comprising: A lens group in which a plurality of condenser lenses are arranged along a predetermined direction that traverses an optical path of light from a light source, and a plurality of units arranged in the predetermined direction, and are arranged in the predetermined direction from the lens group. A polarizing element in which each of the plurality of light beams is incident on a corresponding unit of the plurality of units; and an optical system that illuminates the image forming unit with polarized light from the plurality of units of the polarizing element. Then, each of the plurality of units of the polarization element divides the incident light into a reflected light and a transmitted light whose polarization directions are orthogonal to each other, and one of the reflected light and the transmitted light and advances the other. In almost the same direction A reflecting section to direct, and a modulating section that changes the polarization direction of at least one of the reflected light and the transmitted light to match the polarization directions of the two,
The image projection apparatus further comprises a light-shielding portion at a position corresponding to the reflection portion of each of the plurality of units. 2. The image forming means includes a liquid crystal display element,
The image projection apparatus according to claim 1, further comprising a polarizing plate provided on the light emitting side of the liquid crystal display element, the polarizing plate being separated from the liquid crystal display element. 3. The image projection apparatus according to claim 1, wherein the illumination optical system includes a lamp as the light source and a concave mirror that reflects light from the lamp toward the polarization element. 4. The image projection apparatus according to claim 1, wherein, in each unit, the modulation unit and the division unit are both provided on a prism that constitutes the unit. 5. The image projection apparatus according to claim 1, wherein the lens group includes a fly-eye lens having lenses arranged in the predetermined direction or a lenticular lens having lenses arranged in the predetermined direction. 6. The modulator is a crystal such as mica or quartz,
A stretched polymer film, a low-molecular liquid crystal aligned with molecular axes aligned, a side-chain polymer liquid crystal, or a polymer liquid crystal in which a low-molecular liquid crystal is dispersed in a polymer. 1. The image projection device according to 1. 7. The illumination optical system has a plurality of dichroic mirrors for obtaining the polarized lights of the three colors of R, G, B, and the image forming means has the three colors of R, G, B. It has three liquid crystal display devices which form image light of three colors R, G, B by polarized light, and the projection optical system combines and projects the image light of three colors R, G, B. The image projection device according to claim 1, wherein the image projection device is a display device.