JPH08184801A - Polarization direction alignment element and liquid crystal video projector using the same - Google Patents

Abstract

PURPOSE: To improve its conversion efficiency ranging to a wide visible ray region and to reduce a manufacturing cost also when unpolarized light is converted to a prescribed polarization. CONSTITUTION: A unit element 10C constituting a polarization direction alignment element is constituted of a polarizing beam splitter 11, a first total reflection prism 12 and a second total reflection prism 13. A light beam 3C is made incident on the polarizing beam splitter 11 to be split to two polarization components orthogonally intersecting with each other. The first polarized component 14A is emitted from the front surface 11B of the polarizing beam splitter 11, and the second polarized component 14B is reflected sidewards by an action surface 11A, and is reflected upward by the reflection surface 12A of the first total reflection prism 12, and is reflected forward by the reflection surface 13A of the second total reflection prism 13 to be emitted from the front 13B of the second total reflection prism 13. Two polarization components 14A, 14B emitted from the element become parallel to each other in the beam advance direction and the polarizing direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polarization direction alignment element for converting unpolarized light into polarized light and a liquid crystal video projector using the same.

[0002]

2. Description of the Related Art In recent years, a liquid crystal video projector has been widely known in which a liquid crystal plate is used to modulate illumination light by a predetermined image signal and the modulated light is enlarged and projected on a screen.

Such a liquid crystal video projector is required to have a higher screen brightness, and in accordance with the demand, two light sources are used, as described in, for example, Japanese Patent Laid-Open No. 3-294841. The corresponding liquid crystal plates are illuminated by the light beams from these light sources, and the light beams of the two systems transmitted through the respective liquid crystal plates are combined by the light combining means,
It is known that the amount of projection light is increased by this.

In addition, the liquid crystal cell, which is the main body of the liquid crystal plate, must have a single direction of polarization of the illumination light due to its nature.
Therefore, a polarizing plate is usually provided on the front surface and the rear surface of the liquid crystal cell so that only a predetermined unidirectional polarization component is allowed to enter the liquid crystal cell.

That is, in the polarizing plate provided on the front surface of the liquid crystal cell, the light component in the non-selected direction is converted into heat by absorption, and theoretically only half of the total light amount can be used.

Therefore, depending on the above prior art, 2
Although the light beams from one light source are used as the illumination light, the light amount equivalent to the light amount from one light source is effectively used.

As a technique for solving such a problem, the technique described in JP-A-6-202041 is known.

That is, in this technique, a polarization beam splitter, a total reflection prism, and λ / 2 are provided between a light source and a liquid crystal plate.
A polarization direction alignment member made of an optical phase plate is provided. This polarization direction alignment member transmits the P polarization component of the light beam from the light source and reflects the S polarization component at a right angle by the polarization beam splitter, and reflects the reflected S polarization component at a further right angle by the total reflection prism. Then, the light is aligned in parallel with the P-polarized component transmitted through the polarization beam splitter, and further, the polarization direction of the S-polarized component is rotated by 90 ° by the λ / 2 optical phase plate so as to be converted into the P-polarized component. As a result, the light quantity of the light beam emitted from the light source is effectively used as the illumination light of the liquid crystal plate.

[0009]

By the way, in the above prior art, a λ / 2 optical phase plate is used to rotate the polarization plane of the P-polarized component by 90 °. However, when the plane of polarization is rotated by the optical phase plate, its rotation angle depends on the wavelength of light. Therefore, for light of a specific wavelength, even if the plane of polarization can be rotated by a desired angle, Light becomes elliptically polarized light, and the amount of light on a desired plane of polarization decreases.

Therefore, except for the light whose polarization plane is rotated by a desired angle, it has to be cut in the latter stage of this λ / 2 optical phase plate, which eventually causes a problem that the conversion efficiency of the polarization component is lowered, and further the white color is generated. When a color image is projected by optical illumination, there are problems such as color reproducibility of the projected image and color unevenness.

Further, since the 1/2 optical phase plate is also expensive, there is a problem that the cost of the entire apparatus becomes high.

Therefore, the present invention uses a polarization direction alignment element which has good conversion efficiency over a wide visible light region and is inexpensive in the case of converting unpolarized light into light of a predetermined polarization. An object of the present invention is to provide a liquid crystal video projector that generates illumination light of a liquid crystal plate.

Further, in the prior art relating to the liquid crystal video projector as shown in FIG. 12 of Japanese Patent Laid-Open No. 6-202041, the P polarization component transmitted through the polarization beam splitter and the P polarization converted by the 1/2 optical phase plate are used. The components are combined by a wedge prism, but in such a conventional technique, when the wedge prism and the liquid crystal plate are brought closer to each other, the beams of the two polarized components to be combined have a large angle with each other. Incident on the liquid crystal plate, and each illuminates the liquid crystal plate at an angle, so that vignetting occurs on the liquid crystal plate and the projection lens, and there is a problem that the utilization efficiency of the illumination light is reduced by that amount. If the distance between the wedge prism and the liquid crystal plate is increased, there is a problem that the optical system becomes large. Further, since the polarization direction alignment member is arranged near the light source at a position where the light beam diameter is large, there is a problem that each optical element constituting this member, and eventually the optical system, becomes large in size, which is against the request for cost reduction. It was

The present invention has been made in order to solve such a problem, and it is possible to prevent the utilization efficiency of illumination light from being lowered, downsize the optical system, and reduce the cost.
It is another object to provide a liquid crystal video projector.

[0015]

A polarization direction alignment element according to the present invention splits a light beam into first and second polarization components which are orthogonal to each other, and the first polarization component is directed forward. A polarization beam splitter that respectively emits the second polarization component to the side, and a first polarization component that reflects the first polarization component emitted to the front or the second polarization component emitted to the side upward or downward. A total reflection mirror member and a second total reflection mirror member that reflects the first polarized component reflected upward or downward sideways or the second polarized component reflected upward or downward forward. And a second polarization component emitted from the polarization beam splitter and a first polarization component reflected from the second total reflection mirror member, or a first polarization component emitted from the polarization beam splitter. And the second total internal reflection Mira And it is characterized in that formed by constituting the beam traveling direction and the polarization direction of the second polarized light component reflected from the member to be parallel to each other.

Further, the polarization direction aligning elements according to claim 1 which are bilaterally symmetric with each other are combined, and from one polarization direction aligning element the upper left and lower right, and from the other polarization direction aligning element the upper right. It is also possible to configure such that the polarization components whose beam traveling direction and polarization direction are parallel to each other are emitted from the lower left and.

Further, it is also possible to construct a structure in which the left-right symmetric combination is further combined in the vertical symmetry so as to emit eight polarized beams having parallel polarization directions.

The above-mentioned total reflection mirror member is a general term for members having a surface for totally reflecting light, and includes, for example, a total reflection prism as well as a total reflection mirror.

Further, the liquid crystal video projector of the present invention is a liquid crystal projector using the above-mentioned polarization direction alignment element, wherein the polarization direction alignment element emits illumination light and the polarization direction alignment element emits light. And a liquid crystal plate that modulates the polarized light component with a predetermined image signal, and the polarized light transmission direction is set so as to transmit the polarized light component, and the modulated polarized light component is projected. And a projection lens for enlarging and projecting on a surface.

Further, an optical system for reducing the diameter of the light beam from the light source and for making the light beam into a parallel light flux is arranged on the optical path between the light source and the polarization direction alignment element. It is preferable to have a structure.

[0021]

According to the above-described polarization direction alignment element of the present invention, the light beam from the light source is split into two polarization components orthogonal to each other in the polarization beam splitter, and one polarization component is divided into two total reflections. The polarization plane is rotated by 90 ° with the mirror member so that the other polarization component directly emitted from the polarization beam splitter is parallel to the beam straight direction and the polarization direction, and the light beam emitted from the light source. Can be converted into polarized light having a plane of polarization in a predetermined direction with almost no reduction in the amount of light.

Further, since the plane of polarization of the polarization component is rotated by the light reflection of the two total reflection mirror members, when the light wavelength is changed as in the prior art using the 1/2 optical phase plate, a straight line is obtained. The polarized light does not become an elliptically polarized light, and the conversion efficiency of the polarized light component can be approximately 100% over a wide visible light region. Therefore, it is possible to obtain polarized light in which the rotation angles of the polarization planes are aligned over a wide visible light region, and it is possible to use substantially the entire amount of light in this wide visible light region as illumination light.

Further, the manufacturing cost can be reduced by using the two total reflection mirror members without using the 1/2 optical phase plate.

Further, a polarizing beam splitter and two total reflection mirror members arranged in a predetermined positional relationship are symmetrically combined to emit four polarized beams whose beam traveling directions and polarization directions are aligned. It is possible,
The light beam emission area and the emission light amount can be inexpensively and easily increased.

The liquid crystal video projector of the present invention uses the polarization direction alignment element when converting the polarization component to obtain the polarization component for illuminating the liquid crystal plate, and the polarization plane is spread over a wide visible light region. Since it is possible to obtain polarized light with a uniform rotation angle, it is possible to use almost the entire amount of light in this wide visible light region as the illumination light, and further, there is a problem of color reproducibility of the projected image and color unevenness. Problems can also be resolved. Further, the manufacturing cost of the device can be reduced.

In the liquid crystal video projector according to the present invention, an optical system for reducing the diameter of the light beam from the light source and making the light beam into a parallel light beam is provided on the optical path between the light source and the polarization direction alignment element. By arranging, the beam diameter can be narrowed down at the position where the light beam is incident on the parallel direction alignment element, so that the size of the polarization direction alignment element that converts the polarization component can be formed small, and It is possible to reduce the size and manufacturing cost. Further, the light amount distribution of the light beam can be made uniform by narrowing down the beam diameter.

Further, by forming a parallel light flux, the light beam of the polarization component emitted from this polarization direction alignment element also becomes a parallel light flux and can be used as it is as illumination light of the liquid crystal plate, and in the liquid crystal plate and the projection lens. It is possible to obtain illumination light with high utilization efficiency without vignetting.

[0028]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic view showing a liquid crystal video projector according to an embodiment of the present invention. As shown in the figure, this liquid crystal video projector includes two parabolic reflectors 1A and 1B as reflecting means and two halogen lamps or metal halide lamps arranged near the focal points of the reflectors 1A and 1B. Light sources 2A and 2B and light source 2
The light beams 3A and 3B emitted from A and 2B directly or via the reflecting mirrors 1A and 1B are reflected by the reflecting surfaces 4A and 4A,
A double-sided total reflection mirror 4 which is incident on 4B and reflects the light beams 3A and 3B at right angles on its reflection surfaces 4A and 4B, and light beams 3A and 3B which are reflected at right angles by the double-sided total reflection mirror 4 respectively. Total reflection mirrors 5A and 5B that reflect at right angles, and polarization direction alignment element 10A and S polarization component L that receive the light beams 3A and 3B reflected from these total reflection mirrors 5A and 5B and emit _P polarization component LP. _The polarization direction alignment element 10B that emits _S and the polarization direction alignment element 10
A single-plate color liquid crystal plate 6A and a single-plate color liquid crystal plate 6B as image forming means for modulating the P polarization component L _P from A and the S polarization component L _S from the polarization direction alignment element 10B in accordance with a predetermined image signal. Then, the P-polarized component L _P transmitted through the single-plate color liquid crystal plate 6A is transmitted, and the S-polarized component L _S transmitted through the single-plate color liquid crystal plate 6B is reflected on the working surface (evaporation film surface) 7A, and these 2 Two polarization components L _P , L
_It is composed of a second polarization beam splitter 7 for combining _S and a projection lens 9 for magnifying and projecting the combined two polarization components L _P and L _S on a screen 8.

As described above, in this liquid crystal video projector, the light beams 3A and 3B emitted from the two light sources 2A and 2B in directions orthogonal to each other are total reflection surfaces 4A and 4B of the double-sided total reflection mirror 4 opposite to each other. Is reflected at a right angle.

Next, the two reflected light beams 3
Each of A and 3B is reflected by the total reflection mirrors 5A and 5B again at a right angle, and the corresponding polarization direction alignment element 10 is provided.
A and 10B are irradiated.

As will be described later, the polarization direction aligning elements 10A and 10B are a combination of four unit elements in which a polarizing beam splitter and two total reflection prisms are arranged in a predetermined positional relationship in a predetermined positional relationship. light beam 3A of irradiated unpolarized, 3B to the polarization direction aligned element 10A in the P-polarized component L _P, also in the polarization direction aligned elements 10B S-polarized component L
Convert to _S without reducing the light intensity.

The two polarization components L _P and L _S emitted from the polarization direction aligning elements 10A and 10B are applied to the two single-plate color liquid crystal plates 6A and 6B provided correspondingly.

The single-plate color liquid crystal plate 6A is provided with a polarizing plate and a liquid crystal cell which are set so that the polarized light transmission direction and the action direction are aligned with respect to the P-polarized component L _P irradiated on the single-plate color liquid crystal plate 6A. The liquid crystal plate 6B includes a polarizing plate and a liquid crystal cell that are set so that the polarization transmission direction and the action direction of the S-polarized component L _S irradiated on the liquid crystal plate 6B are aligned. As a result, both the P-polarized component L _P and the S-polarized component L _S are effectively modulated by the same predetermined image signal input at the same timing in the single-plate color liquid crystal plate 6A and the single-plate color liquid crystal plate 6B. It will be processed.

Therefore, unlike the prior art, the situation in which approximately half the light amount of the unpolarized light beam from the light source is not cut by the polarizing plate of the liquid crystal plate does not occur, and the light energy can be effectively used and cut. The conventional problem that the light is converted into heat to cause thermal deformation of the liquid crystal plate can be improved.

Incidentally, these single plate color liquid crystal plates 6A, 6
On the rear surface of B, a polarizing plate whose polarization transmission direction is set to a predetermined direction is arranged so as to transmit the modulated polarized light, like a normal liquid crystal plate.

In this way, the two single-plate color liquid crystal plates 6 are
A, 2 two polarized component L _P is modulated by 6B, L _S as is depicted, it enters from a direction perpendicular to each other on the second polarizing beam splitter 7.

In the second polarization beam splitter 7, the P-polarized component L _P is transmitted through the working surface (deposited film surface) 7A, while the S-polarized component L _S is reflected by the working surface 7A. , Modulated and carrying image information 2
The two polarization components L _P and L _S are combined by the second polarization beam splitter 7 and emitted in the direction of the projection lens 9. After that, the combined two polarization components L _P and L _S are projected on the screen 8 by the projection lens 9, and a predetermined image is displayed on the screen 8. As a result, the screen brightness can be sufficiently increased by effectively utilizing the total amount of light beams 3A and 3B emitted from the two light sources 2A and 2B.

The second polarization beam splitter 7 is arranged so that the images related to the image information carried by the two polarization components L _P and L _S are surely overlapped on the screen 8.
It is necessary to adjust the beam traveling direction and the beam position of the two polarization components L _P and L _S incident on the beam.

Further, in this embodiment, each light source 1A,
An optical system for reducing the beam diameters of the light beams 3A and 3B and for making the light beams 3A and 3B into parallel light beams is provided on the optical path between the 1B and the corresponding polarization direction alignment elements 10A and 10B. Has been done. This optical system will be described with reference to FIG.

That is, the light beam 3 emitted from the light source section including the parabolic reflectors 1A and 1B and the light sources 2A and 2B.
A and 3B are convex lenses 10 through a filter (UV / IR cut filter) 101 for cutting ultraviolet rays and infrared rays.
2 and a concave lens 103 to enter a light beam diameter conversion optical system.

In this light beam diameter conversion optical system, the light beams 3A and 3B are first made into a focused light beam by the convex lens 102,
Then, the concave lens 103 forms a parallel light beam. The beam diameters of the light beams 3A and 3B emitted from the concave lens 103 are much narrower than the beam diameters of the light beams 3A and 3B emitted from the light source section. It is possible to reduce the size of the polarization direction alignment elements 10A and 10B that are irradiated with light. Further, compared to the light beams 3A and 3B immediately after being emitted from the light source unit, the light amount distribution can be made more uniform, and the brightness unevenness of the projected image displayed on the screen 8 can be reduced. Further, since the polarization direction alignment elements 10A and 10B are irradiated with the parallel light beams 3A and 3B which have become light beams, the polarization component L emitted from the polarization direction alignment elements 10A and 10B.
_P and L _S are also parallel light beams, and the liquid crystal plates 6A and 6B remain as they are.
It can be used as the illumination light of.

Next, the polarization direction alignment elements 10A and 10 described above are used.
B will be described in more detail with reference to FIGS.

FIG. 3 shows the polarization direction alignment elements 10A and 10B.
10 shows a unit element 10C constituting the above. That is,
The unit element 10C is composed of a polarization beam splitter 11, a first total reflection prism 12 and a second total reflection prism 13 whose surfaces adjacent to each other are bonded. The polarization beam splitter 11 and the second total reflection prism 13 are cubic blocks of the same size, and the first total reflection prism 12 is a triangular prism block of a size obtained by cutting the cube block in half. The light beam 3C is incident on the polarization beam splitter 11, and is split into two polarization components orthogonal to each other in the polarization beam splitter 11. That is, the first polarization component 14A passes through the working surface (deposition film surface) 11A and is emitted from the front surface 11B of the polarization beam splitter 11, while the second polarization component 14A
Of the polarized light component 14B of the second total reflection prism 13 is reflected laterally on the working surface 11A, upwards on the reflection surface 12A of the first total reflection prism 12, and further reflected on the reflection surface 13 of the second total reflection prism 13.
This second total internal reflection prism is reflected forward at A.
It is ejected from the front surface 13B of 13. The two reflective surfaces 12A,
13A is arranged so that the irradiated beam of the second polarization component 14B is incident at an incident angle of 45 °, and the second polarization component 14B is reflected at a right angle on these reflection surfaces 12A and 13A. . Therefore, the front surface 13 of the second total reflection prism 13 is
The second polarization component 14B when emitted from B becomes a state in which the polarization plane is rotated by 90 ° with respect to the second polarization component 14B when reflected from the working surface 11A of the polarization beam splitter 11, and eventually , The second polarization component 14B emitted from the front surface 13B of the second total reflection prism 13 is the polarization beam splitter 11
The first polarized light component 14A emitted from the front surface 11B of the light source and the beam traveling direction and the polarization direction thereof are parallel to each other.

As a result, substantially the total amount of light of the unpolarized light beam 3C is converted into polarized light having a polarization plane in a predetermined direction.

Further, as shown in FIG. 4, a unit element 10C including a polarization beam splitter 11, a first total reflection prism 12 and a second total reflection prism 13, and this unit element 10C.
By combining the unit element 10D including the polarization beam splitter 21, the first total reflection prism 22 and the second total reflection prism 23 in the front-rear direction in which the arrangement of the optical members is symmetrical with respect to 10C, the two Four polarization components 14A, 14B, 24A, 24B can be generated from the light beams 3C, 3D.

That is, the unit element 10C causes the light beam 3C incident on the polarization beam splitter 11 to have a first polarization component 14A and a first polarization component 14A whose beam traveling direction and polarization direction are parallel to each other. Two polarization components 14B
And the unit element 10D converts the light beam 3D incident on the polarization beam splitter 21 into the first polarization component.
24A, and the first polarization component 24A is converted into a second polarization component 24B whose beam traveling direction and polarization direction are parallel to each other.

If the beam traveling directions of the two unpolarized light beams 3C and 3D are parallel to each other, the polarization components 14A, 14B and 24 emitted from these two unit elements 10C and 10D.
The beam traveling directions and the polarization directions of A and 24B are parallel to each other.

In FIG. 3 and FIG. 4, the unit element 10C,
Light beams 3C and 3D incident on 10D and polarization components 14A, 14B and 24 emitted from these unit elements 10C and 10D.
The beams A and 24B are shown as straight lines, but in reality, the respective light beams 3C and 3D are incident on the entire area of the rear surface of the corresponding polarization beam splitters 11 and 21, and the polarization beam splitters 11 and 21 and Since the light is emitted from the entire area in front of the total reflection prisms 13 and 23 of No. 2, the polarization beam splitter 1
The polarization components aligned in the same polarization direction are emitted from the entire area of the square surface corresponding to four times the area of the front surface of 1, 21.

The light beam 3C input to the unit element 10C is transmitted through the first total reflection prism 22 of the unit element 10D, and the polarization component 24A emitted from the unit element 10D is the first total reflection element of the unit element 10C. Although it passes through the reflection prism 12, the first total reflection prisms 12 and 22 are substantially transparent in the front-rear direction, and even when they pass through the first total reflection prisms 12 and 22, they are substantially transparent. The light intensity does not decrease.

FIG. 5 shows a specific configuration of the polarization direction aligning elements 10A and 10B in the above embodiment, which is a combination of the two unit elements 10C and 10D shown in FIG.
Further, they are vertically symmetrically combined, and eventually they are constituted by combining four unit elements 10C shown in FIG.

Therefore, the light beam 3 emitted from the light source section composed of the parabolic reflectors 1A and 1B and the light sources 2A and 2B.
A and 3B are incident from the rear surfaces of the four polarization beam splitters 11 and 21 of the polarization direction alignment elements 10A and 10B, and the four polarization beam splitters of the polarization direction alignment elements 10A and 10B.
The beam traveling direction and the polarization direction are aligned from the front surfaces of 11 and 21 and the four second total reflection prisms 13 and 23.
The polarized light components 14A, 14B, 24A, 24B of the book are converted and emitted.

As shown in the figure, the polarization direction aligning elements 10A and 10B in this embodiment are polarization beam splitters 11 and 21 and first total reflection prisms 12 and 22, which are cubic blocks having substantially the same shape, and half of them. Since the second total reflection prisms 13 and 23, which are triangular prism blocks of a size, are combined and the manufacturing is easy, the manufacturing cost is also low.

In addition, the polarization directions of the polarizations emitted from the polarization direction alignment elements 10A and 10B are changed to the single-plate color liquid crystal plates 6A and 6A.
It is preferable to adjust the arrangement angle of the polarization direction alignment elements 10A and 10B so as to match the polarization transmission direction of the polarizing plate arranged on the front surface of B.

Further, except when the polarization directions of the polarized light emitted from the liquid crystal plates 6A and 6B are orthogonal to or parallel to the vertical direction of the display image, the liquid crystal plates 6A and 6B.
It is necessary to rotate the polarization direction of the polarized light emitted from B to a predetermined direction and then make it enter the polarization beam splitter 7. For example, in the case where the above two directions form an angle of 45 °, a rotatory element such as a 1/2 optical phase plate is arranged on the front surface of the polarization beam splitter 7, whereby the polarization plane of the polarized light is 45 °.
Just rotate it.

The polarization direction aligning element and the liquid crystal video projector of the present invention are not limited to those in the above embodiment, and various modifications can be made.

For example, the unit elements shown in FIGS. 3 and 4 and the combination of the unit elements can be used as they are as the polarization direction aligning element, and an arbitrary number of unit elements can be combined to form the polarization direction aligning element. It is also possible to do so. It is also possible to use a total reflection mirror instead of the above total reflection prism.

Further, as the liquid crystal video projector, it is possible to omit the total reflection mirrors 4, 5A, 5B of the above-mentioned embodiment and have a structure as shown in FIG. That is,
The light beams 203 A and 203 B from the light sources 202 A and 202 B are directly polarized in the polarization direction aligning element 210 without passing through a reflecting member.
It is also possible to make it incident on A and 210B.

The symbols given to the respective members in FIG. 6 are represented by adding 200 to the symbols given to the respective members having the same function in FIG.

Further, if the constitution of the apparatus of the above-mentioned embodiment is adopted, the back focal length of the projection lens can be made relatively short and the astigmatism of the projection lens can be reduced.

Further, the light amounts of the two polarization components L _P and L _S can be made equal, and further, the distances from the light sources 2A and 2B to the corresponding single color liquid crystal plates 6A and 6B can be made equal. It is possible to reduce the color unevenness of the image formed on the screen 8 by the combined two polarization components.

Of the image signals input to the single-plate color liquid crystal plates 6A and 6B, one is an image signal for the right eye and the other is an image signal for the left eye.
Alternatively, it is possible to display a stereoscopic image viewing image on the screen 8 by moving the single-plate color liquid crystal plates 6B in parallel in the direction perpendicular to the optical axis by a slight distance.
It is to be noted that a viewer uses predetermined polarized glasses when viewing the stereoscopic image.

In the above embodiment, the light source section 1A,
Two sets of each of 1B, 2A and 2B, polarization direction alignment elements 10A and 10B and color liquid crystals 6A and 6B are provided, but it is also possible to provide one set of each. In this case, the polarization beam splitter for beam combination is unnecessary.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a liquid crystal video projector according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining in detail a part of the embodiment apparatus shown in FIG.

FIG. 3 is a schematic view showing a part of a polarization direction alignment element of the present invention.

FIG. 4 is a schematic view showing a part of a polarization direction alignment element of the present invention.

FIG. 5 is a schematic view showing a polarization direction alignment element of the present invention.

FIG. 6 is a schematic view showing an embodiment apparatus different from the embodiment apparatus shown in FIG.

[Explanation of symbols]

1A, 1B, 201 A, 201 B Parabolic reflector 2A, 2B, 202 A, 202 B Light source 3A, 3B, 3C, 3D, 203 A, 203 B Light beam 4 Double-sided total reflection mirror 7A, 11A, 207 A Working surface 5A, 5B Total reflection mirror 6A, 6B, 206 A, 206 B Single plate color liquid crystal plate 7, 11, 21, 207 Second polarization beam splitter 8, 208 Screen 9, 209 Projection lens 10A, 10B, 10C, 10D, 210 A, 210 B Polarization direction alignment element 12, 22 First total reflection prism 4A, 4B, 12A, 13A Reflective surface 13, 23 Second total reflection prism 14A, 14B, 24A, 24B Polarization component 102 Convex lens 103 concave lens

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G03B 33/12 H04N 5/74 A

Claims (4)

[Claims] 1. A polarization which separates one light beam into first and second polarization components which are orthogonal to each other, and emits the first polarization component forward and the second polarization component laterally, respectively. A beam splitter, a first total reflection mirror member that reflects the first polarized light component emitted forward or the second polarized light component emitted laterally upward or downward, and the first total reflection mirror member reflected upward or downward. And a second total reflection mirror member that reflects the first polarized component sideways or the second polarized component reflected upward or downward forward, and the second total reflection mirror member emitted from the polarization beam splitter. Two polarization components and a first polarization component reflected from the second total reflection mirror member, or a first polarization component emitted from the polarization beam splitter and reflected from the second total reflection mirror member Beam with second polarization component A polarization direction alignment element, which is configured so that a traveling direction and a polarization direction are parallel to each other. 2. The polarization direction aligning elements according to claim 1, which are bilaterally symmetric with each other, are combined from one of the polarization direction aligning elements from upper left and lower right, and the other polarization direction aligning element is upper right. And a polarization direction alignment element, which is configured so that polarization components whose beam traveling directions and polarization directions are parallel to each other are emitted from the lower left. 3. A liquid crystal projector using the polarization direction alignment element according to claim 1, wherein the polarization direction alignment element emits illumination light, and a polarization component emitted from the polarization direction alignment element. And a projection lens for enlarging and projecting the modulated polarization component on a projection surface, and a liquid crystal plate that modulates the polarization component with a predetermined image signal. 4. An optical system for reducing the diameter of the light beam from the light source and for making the light beam a parallel light beam is arranged on the optical path between the light source and the polarization direction alignment element. The liquid crystal video projector according to claim 3, characterized in that: