JPH10221647A - Polarization illuminating device and polarizing beam splitter array - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the usage rate of light and to attain minituarization by arranging polarizing beam splitter array with specified configuration in an optical path between a first lens plate and the second lens plate constituting an integrator optical system with it. SOLUTION: Polarizing beam splitter array 20 is arranged in the immediately proceding position of the second lens plate 13, concretely speaking, in a state adjacent to the light incident surface of the second lens plate 13 or in a close state. In this case, polarizing beam splitter array is the one constituted by arranging plural beam splitter elements provided with an operation for separating an unfixed polarized light which is made incident from one surface (light incident surface) into a P-polarized light and an S-polarized light being the two kinds of linearly polarized lights by a polarization separating film, for example and for emitting the two kinds of polarized lights from mutually adjacent light emitting surfaces on the other surface in an arrayal state along one plane. Therefore, any light irradiated from the second lens plate 13 becomes the linearly polarized light where the polarizing directions are aligned.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a polarization illuminator and a polarization beam splitter array.

[0002]

2. Description of the Related Art In recent years, an apparatus for enlarging and projecting an image formed on a liquid crystal display element onto a screen has been proposed. In such an image enlargement projection device, it is necessary to illuminate a liquid crystal display element, which is an object to be irradiated, with linearly polarized light having a predetermined polarization direction by using a polarized light illumination device. Conventionally, as such a polarized light illuminating device, one having the configuration shown in FIG. 9 has been proposed. In FIG. 9, X is a system optical axis, 110 is a light emitting unit of a light source lamp (not shown),
111 is a converging concave reflecting mirror, 112 is a first lens plate,
113 is a second lens plate, 114 is a condenser lens,
Reference numeral 115 denotes a liquid crystal display element, and the first lens plate 112 and the second lens plate 113 constitute an integrator optical system. The polarizing beam splitter 120 is disposed at a position on the light source lamp side of the first lens plate 112.

In this polarized lighting device, the light emitting section 11
The light radiated from 0 is converged by, for example, the concave reflecting mirror 111, and the first light disposed in the optical path of the converged light.
The light emitting unit 1 is formed by each of the lens elements of the lens plate 112 of
The image of 10 is made incident on the corresponding lens element of the second lens plate 113, whereby the image of the lens element of the first lens plate 112 is superimposed on the liquid crystal display element 115 by the second lens plate 113. It is projected and illuminated. As shown in FIG. 10, the liquid crystal display element 115 includes polarizing plates P1 on the light incident side and the light emitting side of the liquid crystal layer LC, respectively.
And P2 are arranged, and light transmitted therethrough is projected on a screen by a projection lens (not shown). Reference numeral 117 denotes an aperture regulating member of the liquid crystal display element 115.

A short arc lamp such as a metal halide lamp is generally used as a light source lamp in this type of polarized light illuminating device. Light emitted from a light emitting portion due to the arc is irregularly polarized light. The light applied to the liquid crystal layer of the liquid crystal display element needs to be linearly polarized light. For this reason, it is necessary to dispose a polarizing plate that absorbs one component of the irregularly polarized light before the liquid crystal layer. However, since this polarizing plate is generally low in heat resistance, when it is configured to be arranged in such a manner that the indeterminate polarized light from the light source lamp is directly incident thereon,
There is a problem that the types of light that can be used are limited. Under such circumstances, in the above-mentioned polarized light illuminating device, the indefinitely polarized light from the light source lamp is polarized by the polarization beam splitter 1.
20 separates into two kinds of linearly polarized light, that is, P-polarized light and S-polarized light, and only the polarized light in one polarization direction according to the polarization characteristics of the polarizing plates P1 and P2, for example, only the P-polarized light, is the first lens. It is configured to be incident on the plate 112. Then, the polarized light in the other polarization direction, in this case S
The polarized light is returned to the concave reflecting mirror side in the polarizing beam splitter 120.

However, when only one of the two types of polarized light is used, naturally, the utilization rate of the light emitted from the light-emitting portion is extremely low, and the polarized light that is not used is, for example, a lamp house or a lamp house. Since it is absorbed by the casing of the device and converted into heat, there is a problem that exhaust heat treatment is required. In order to solve such a problem, while separating indefinitely polarized light and using one polarized light as it is,
The other polarized light is propagated through a path different from the one polarized light, and the polarization direction is aligned with the one polarized light by changing the polarization direction by a half-wave plate inserted in the path. Thus, there has been proposed a polarized light illuminating device configured to be able to use the other polarized light as well.

However, in the configuration of the conventional polarization illuminator, each of the beam splitter elements constituting the polarization beam splitter 120 is connected to the first lens plate 11.
In connection with the need to have a relatively large aperture area to cover the aperture area of the second lens element, it is necessary to increase the thickness of the beam splitter element inevitably. The beam splitter 120 has a problem that its thickness in the system optical axis X direction is large.

Further, as a result, not only the length in the direction of the system optical axis X becomes large, but also the optical path expands accordingly, so that the lens element of the second lens plate 113 needs to have a large diameter. Furthermore, since a large aperture area is also required as the projection lens, the entire system becomes large, and in the end, this type of apparatus which is required to be downsized can meet such a demand. There is a problem that it cannot.

On the other hand, when the arrangement position of the polarizing beam splitter is set between the first lens plate 112 and the second lens plate 113, the integrator optical system includes:
Since the image of the first lens plate 112 is superimposed and projected on the liquid crystal display element 115 by the second lens plate 113, it is very difficult to secure a dedicated optical path for each polarized light separated by the polarizing beam splitter. Is difficult, and furthermore, one-half of the polarized light is
Where processing by wave plates is also required, one or both polarized light beams are inevitably sacrificed due to the placement of such an optical processing member in the optical path, resulting in However, there is a problem that a sufficiently high light utilization rate cannot be realized.

[0009]

DISCLOSURE OF THE INVENTION The present invention has been made based on the above circumstances, and its object is to provide:
It is an object of the present invention to provide a polarized light illuminating device capable of realizing illumination of a liquid crystal display element in a state where the utilization rate of light emitted from a light source is sufficiently high and reducing the size of the entire device. It is another object of the present invention to provide a polarizing beam splitter array having a smaller thickness than an opening area.

[0010]

SUMMARY OF THE INVENTION A polarized light illuminating apparatus according to the present invention comprises a light source lamp, an optical system for focusing light emitted from the light source lamp, and a plurality of light sources arranged in an optical path of the focused light. A first lens plate comprising a lens element of
A second lens plate comprising a plurality of lens elements corresponding to the lens elements of the first lens plate, and a first lens plate and a second lens plate which constitute an integrator optical system together with the first lens plate And a polarizing beam splitter array disposed in the optical path between the P-polarized light and the separated P-polarized light and S-polarized light, the polarization direction changing means for aligning one polarization direction with the other polarization direction, The polarizing beam splitter array separates the indefinitely polarized light incident from one surface into two types of linearly polarized light, P-polarized light and S-polarized light, and separates the two types of polarized light from the light exit surfaces adjacent to each other on the other surface. A plurality of beam splitter elements having a function of emitting light are arranged side by side, and the polarized light emitted from each lens element of the second lens plate has a uniform polarization direction. There characterized in that it is superimposed illuminated the irradiated object through the liquid crystal display device.

In the above, it is preferable that the polarizing beam splitter array is disposed immediately before the second lens plate. Further, the value of the ratio t / L of the thickness t in the system optical axis direction of the polarizing beam splitter array to the distance L between the first lens plate and the second lens plate may be 0.2 or less. preferable.

Further, the polarizing beam splitter array includes:
A plurality of beam splitter elements are a plate-like body arranged along a plane perpendicular to the system optical axis and corresponding to the lens elements of the first lens plate, and each of the beam splitter elements has an isosceles triangular cross section at right angles. The entire cross section of a state in which two of the columnar prism portions are overlapped so that one of the equal sides of one of the prism portions and one of the equal sides of the other prism portion coincide with each other forms a parallelogram, In one prism part of the beam splitter element,
The surface on the other side of the equilateral side is a light incident surface and a polarization separation film is formed on the surface on the hypotenuse, and in the other prism portion, the surface on the hypotenuse is a light reflection surface. In addition, the surface on the other side of the same side may be a light emitting surface (this configuration is referred to as “separation plane parallel type” in this specification).

In the above-mentioned parallel beam splitter array of the splitting plane, the light emitting surface of the transmitted polarized light passing through the polarized light separating film of each beam splitter element and the reflected polarized light reflected by the polarized light separating film. It is preferable that a polarization direction changing film constituting the polarization direction changing means is formed on one of the light emission surfaces.

The second lens plate includes a first lens element element disposed corresponding to a light exit surface of the transmitted polarized light in each beam splitter element of the polarizing beam splitter array of the separation plane parallel type, and a reflection element. Preferably, the second lens element is arranged corresponding to the light exit surface of the polarized light.

The polarizing beam splitter array according to the present invention is a polarizing beam splitter array in which a plurality of beam splitter elements are stacked along one plane, and each of the beam splitter elements includes a pair of splitter units. It is configured to be stacked along one plane,
Each of the pair of splitter units is a state in which two of the columnar prism portions having a right-angled isosceles cross section are overlapped so that one of the equal sides of one prism portion and one of the equal sides of the other prism portion coincide. The entire cross section is a parallelogram, and in one prism portion, a surface relating to the other of the equal sides is a light incident surface and a polarization separation film is formed on a surface relating to the oblique side thereof. In the other prism portion, the surface related to the oblique side is a light reflecting surface and the surface related to the other of the equal sides is a light emitting surface. It is characterized in that two of the entrance surfaces are in a continuous state, and that the light exit surfaces of the splitter units belonging to adjacent pairs and adjacent to each other are continuous. The Do configuration is referred to as "separation plane symmetric.").

In this split plane symmetric polarization beam splitter array, the continuous light emitting surfaces of the splitter units belonging to adjacent pairs and adjacent to each other are provided with:
It is preferable that a continuous polarization direction changing film is formed.

In the polarized light illuminating apparatus of the present invention, when using a polarizing beam splitter array of a separation plane symmetric type, one plane on which a plurality of beam splitter elements are superposed is perpendicular to the system optical axis. , A continuous light incident surface formed by a pair of splitter units may be arranged to correspond to the lens element of the first lens plate.

In the above, the second lens plate is a first lens disposed corresponding to a continuous area of the light exit surface of the transmitted polarized light in each beam splitter element of the polarization beam splitter array of the separation plane symmetric type. It is preferable that the light emitting device be constituted by an element element and a second lens element element arranged corresponding to a continuous area of the light emission surface of the reflected polarized light.

Further, in the present invention, the light source lamp is constituted by a short arc lamp forming a rod-shaped light emitting portion, regardless of whether the polarizing beam splitter array of the parallel type or the symmetric type is used. It is preferable that the longitudinal direction of the elongated image of the light emitting unit coincides with the longitudinal direction of each beam splitter element of the polarizing beam splitter array.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. FIG. 1 is an explanatory diagram showing a basic configuration of the polarized light illumination device of the present invention. In this figure, X is the system optical axis,
Reference numeral 10 denotes a light emitting unit, 11 denotes a converging concave reflecting mirror, 12 denotes a first lens plate, 13 denotes a second lens plate, 14 denotes a condenser lens, and 15 denotes a liquid crystal display element. This liquid crystal display element 1
5 has the same configuration as that shown in FIG. 17
Is a diameter regulating member of the liquid crystal display element 15. Then, the polarizing beam splitter array 20 is connected to the second lens plate 1.
3, specifically, in a state close to or in close contact with the light incident surface of the second lens plate 13.

Here, the "polarizing beam splitter array" means that the non-uniform polarized light incident from one surface (light incident surface) is converted into two types of linearly polarized light P by a polarization separation film.
A plurality of beam splitter elements having the function of separating polarized light and S-polarized light and emitting these two types of polarized light from light emission surfaces adjacent to each other on the other surface are arranged in a line along one plane. Refers to what is composed.

FIG. 2 shows a first lens plate 12 and a second lens plate 13, and a polarizing beam splitter array (hereinafter simply referred to as a "PBS array") 20 of a separation plane parallel type.
FIG. 3 is a cross-sectional view for explaining the PBS array 20, and FIG. 4 is an explanatory view of a beam splitter element (hereinafter, simply referred to as "PBS element") 21 constituting the PBS array 20. . As shown in FIG.
The array 20 has a PBS element 21 composed of a columnar or rod-shaped prism each having a parallelogram cross-section, each of which extends in a direction perpendicular to the paper of FIG. The whole is configured to be stacked so as to be arranged in a vertical direction, and is arranged along a plane perpendicular to the system optical axis X.

Here, as shown in FIG. 4, the PBS element 21 has two columnar prism portions 2 each having an isosceles triangular cross section.
5 and 26, and the entire cross section of a state in which one of the equal sides of one prism portion 25 and one of the equal sides of the other prism portion 26 are overlapped (the boundary surface is indicated by 27) is parallel. It is a quadrilateral. In one of the prism portions 25, a surface on an equal side that is not the boundary surface 27 is a light incident surface 28, and a polarization separation film 30 is formed on a surface on an oblique side thereof. In the other prism portion 26, the light reflecting film 31 is formed on the surface on the hypotenuse side to form a reflection surface, and the polarization direction formed by a half-wave plate on the surface on the equal side that is not the boundary surface 27. A change film 32 is formed.

The PBS element 21 having such a configuration is
Are stacked via the intermediate optical element 22. However, since it is basically sufficient if such a configuration is adopted, for example, a parallelogram whose cross section rises to the right as shown in FIG. In this case, the rod-shaped prisms each having the same cross-sectional shape are vertically stacked, and the polarization separation films 30 and the light reflection films 31 are alternately formed on the sequential boundary surfaces, thereby forming a PBS. The configuration may be such that the element 21 and the intermediate optical element 22 are both formed.

In the above, the specific configuration of the polarization splitting film 30, the light reflecting film 31, and the polarization direction changing film 32 and the specific forming means thereof can use a currently known technique. Means for integrally connecting or connecting the stacked bodies of the PBS element 21 and the intermediate optical element 22 to each other can also use a currently known technique.

As shown in FIG. 2, in the PBS array 20 having the above-described structure, the light incident surface 28 of the PBS element 21 is connected to the first lens plate 12 in relation to the first lens plate 12. In the second lens plate 13 disposed on the light emission side of the system optical axis X of the PBS array 20, the polarization separation is performed. A first lens element element 36a located immediately after the film 30 and a second lens element element 36b located immediately after the polarization direction changing film 32 adjacent thereto are arranged. Therefore, one PBS element 21 has one light incident surface 28 corresponding to one of the lens elements of the first lens plate 12, and two continuous light output surfaces adjacent to the second lens plate 13. 2
One lens element element and one lens element element.

In the polarized light illuminating device having the above structure, the liquid crystal display element 15 is irradiated with light as follows. That is, as shown in FIG. 1, light emitted from the light emitting unit 10 is incident on the first lens plate 12 while being focused by the concave reflecting mirror 11. As shown in FIG. 2, the light that has passed through each of the lens elements 35 is projected by the action of the lens element 35 so as to be focused on the second lens plate 13, so that the light immediately before the second lens plate 13 is emitted. The light is incident on the PBS array 20 arranged at the position.

The light from the lens element 35 is non-constantly polarized light. The non-constantly polarized light is incident on the light incident surface 28 of the PBS element 21 of the PBS array 20. It is separated into polarized light S. Then, as shown in the figure, when the polarized light separating film 30 is an S polarized light transmitting type and a P polarized light reflecting type, the S polarized light transmitted through the polarized light separating film 30 goes straight as it is to the second lens. The P-polarized light that has entered the first lens element element 36a of the plate 13 while being reflected by the polarization splitting film 30 is bent 90 °, is reflected again by the light reflecting film 31, is further bent 90 °, and is emitted. Then, the light passes through the polarization direction changing film 32, is changed to S-polarized light, and then enters the second lens element element 36 b of the second lens plate 13.

However, the light radiated from the second lens plate 13 is linearly polarized light having the same polarization direction, and the indefinitely polarized light from the light emitting section 10 is converted by the polarization splitting film 30 into P-polarized light. Separated into polarized light and S-polarized light,
Even though each optical path is made to be a separate one and one of them is processed by the polarization direction changing film 32 to align its polarization direction with the other polarized light, in practice, the arrangement of additional optical processing members for that purpose is performed. A very high light utilization is achieved because neither polarized light is sacrificed.

More specifically, as is apparent from FIG. 2, in the space between the first lens plate 12 and the second lens plate 13, one lens element of the first lens plate 12 is provided. A non-optical path space 41 is generated between the converging light path 40 (b) related to 35 (a) and the light path 40 (b) related to the adjacent lens element 35 (b). This is because the first lens plate 12
In this case, even if the lens elements 35 are densely arranged, individual light passing therethrough is focused toward the lens elements 35 of the second lens plate 13. The area of the non-optical path space 41 is maximized immediately before the second lens plate 13.

Therefore, in the present invention, the non-optical path space 41 is used.
Is used to arrange an additional optical processing member for one of the separated polarized lights, wherein the additional optical processing member specifically refers to the light reflection in the example of the drawing. This is a prism portion having an isosceles triangular cross section having a film 31 and a polarization direction changing film 32, and is a prism portion 26 in the PBS element 21 in FIG.

That is, the polarization separation film 3 of the PBS element 21
The polarized light (S-polarized light in the example shown in FIG. 1) that passes through the second lens plate 1 inherently follows the integrator optical system.
3 and reflected by the polarization splitting film 30 (P-polarized light in the illustrated example) is processed by the additional optical processing member disposed adjacent to the polarized light to be polarized. The direction is changed to the same polarization direction as the former polarized light, and these polarized lights are emitted from the second lens plate 13.

The non-optical path space 41 is not a space in which no light is present. The non-optical path space 41 has a small light path due to imperfect focusing performance of the lens element 35 of the first lens plate 12 and the like. However, since the light in the non-optical path space 41 is not originally intended for use, and its light intensity is considerably small, the presence of an additional optical processing member is required. The degree to which light in the non-optical path space 41 is sacrificed is very small. In contrast, with the additional optical processing member, the increase in light utilization by being able to utilize both of the separated polarized light is remarkable, and after all, according to the present invention,
Extremely high light utilization can be achieved.

According to the present invention, the PBS array 20
In each of the PBS elements 21, the light incident surface 28 may be small. This is because light from the lens element 35 of the first lens plate 12 is sufficiently focused because the PBS array 20 is disposed immediately before the second lens plate 13. is there. In the PBS element 21 having such a small light incident surface 28, the thickness t is also small. The reason for this is that, as is apparent from FIG. 4, the unit part constituting the PBS element 21 is an isosceles triangle in cross section, and the height H of the light incident surface 28 and the thickness t are equal. is there.

Although not shown in FIG. 2 accurately, the optical path length between the first lens plate 12 and the second lens plate 13 is actually reduced due to the arrangement of the PBS array 20. Above, it becomes larger by the thickness t of the PBS array 20. When the optical path length is increased, the first lens plate 12 on the surface of the liquid crystal display element 15 is correspondingly increased.
Is proportionally reduced, and as a result, in order to obtain a uniform illuminance distribution on the surface of the liquid crystal display element 15, this reduced image size is covered. Thus, it is necessary to increase the opening area of the first lens plate 12 lens element 35. In addition, since the divergence of light on the second lens plate 13 increases as the optical path length increases, the lens element element 36
It is necessary to increase the opening area of the holes a and 36b.

Conversely, if the thickness t of the PBS array 20 can be reduced, the first lens plate 12
Can be made smaller, and in the present invention, the thickness t of the PBS array 20 can be made smaller as described above, and as a result, Unnecessary light is reduced on the liquid crystal display element surface, and the lens element of the second lens plate 13
Specifically, the lens element elements 36a and 36b can be small in diameter, and the opening area of the entire second lens plate 13 can be small. As a result, the utilization rate of light is increased, and it is possible to use a condenser lens or a projection lens having a small aperture, so that the polarization illuminator can be sufficiently reduced in size.

In the present invention, the value t / L of the thickness t of the PBS array 20 to the distance L between the first lens plate 12 and the second lens plate 13 is 0.2 or less. Such dimensions are preferred. By adopting a configuration that satisfies such conditions, the whole can be made sufficiently small.

More specifically, as understood from FIG. 2, in the PBS element 21, polarized light (S-polarized light in the example of FIG. "Light") and the polarization separation film 30.
Is reflected by the light reflecting film 31 (P-polarized light in the example shown in the figure, and then converted to S-polarized light by the polarization direction changing film 32; hereinafter, referred to as "reflected polarized light"). A difference occurs between the two optical path lengths. That is, the optical path length of the reflected polarized light is longer than the optical path length of the transmitted polarized light, and the difference is the vertical distance (H) between the polarization separation film 30 and the light reflection film 31.
be equivalent to. ), And eventually has a length equal to the thickness t of the PBS element 21. As a result, the second lens plate 13
As a result, the image forming position of the light projected on the liquid crystal display element 15 is slightly different between the transmission polarized light and the reflected polarized light in the system optical axis X direction. As a result, for example, on the basis of illumination using only the transmitted polarized light, the light incident area of the reflected polarized light on the liquid crystal display element 15 is slightly larger than the light incident area of the transmitted polarized light.

However, in the configuration satisfying the condition that the value of the ratio t / L is 0.2 or less as described above,
The magnitude of the enlargement error of the light incident area due to the type of the polarized light can be set within the range of the allowance by the aperture regulating member 17 provided in the actual liquid crystal display element 15, and eventually,
Since the error in the light incident area due to the difference in the optical path length between the transmitted polarized light and the reflected polarized light can be reliably absorbed, it is possible to effectively solve the problem and use both polarized lights with high efficiency. Become.

In the above embodiment, the specific configuration can be variously changed. For example, the converging optical system in the basic configuration is a converging concave reflecting mirror 1.
The configuration is not limited to the configuration according to 1, but may be a configuration using another concave reflecting mirror or a lens system as appropriate. Further, the PBS element 21 or the intermediate optical element 22 may be of a composite type constituted by combining columnar prisms having an isosceles triangular cross section and joining them with an appropriate optical adhesive.

In the PBS element 21 described above, the polarization direction changing film 32 is formed on the light exit surface of the other prism portion 26 having the oblique side on which the light reflecting film 31 is formed, as shown in FIG. As described above, instead of the polarization direction changing film 32, the polarization direction changing film 33 may be formed on the surface of the intermediate optical element 22 on the second lens plate 13 side. In this case, the polarized light transmitted through the polarization separation film 30 is subjected to the action of changing the polarization direction, but the polarized light subjected to the action of changing the polarization direction is changed, and there is no essential difference. The same operation and effect can be obtained.

The polarization direction changing films 32 and 33 are made of PB
It is preferably formed on the light emitting surface side of the S element 21, but may be formed on the light incident surface side of the second lens plate 13, for example. Further, a polarization direction changing plate or a polarization direction changing member in which a polarization direction changing film is formed in a region corresponding to the light emission surface of the polarized light having a specific polarization direction of the PBS array 20 may be interposed on a single transparent substrate. it can.

FIG. 6 shows a separation plane symmetric PBS according to the present invention.
FIG. 7 is a cross-sectional view for explaining the array 50, and FIG.
FIG. 4 is an explanatory diagram of a PBS element 51 constituting the array 50.
The PBS array 50 includes a plurality of PBS elements 51 vertically stacked along a plane perpendicular to the plane of the paper, and as shown in FIG.
Is composed of a pair of splitter units 53 and 54 stacked in the vertical direction. In FIG. 6, a portion surrounded by a dashed-line rectangular frame indicates the PBS element 51, and in FIG. 7, a portion surrounded by two dashed-line rectangular frames indicates a splitter unit.

Each of the splitter units 53 and 54 includes, as in the case of the PBS element 21 in the above-described example, two columnar prism portions having a right-angled isosceles cross section and one of the equal sides of one of the prism portions 55. The other prism part 56
The overall cross section in a state of being superimposed so that one of the equal sides thereof coincides with the boundary surface 57 forms a parallelogram. Then, in one of the prism portions 55,
The surface on the other side of the equal side is a light incident surface 58, and the polarization separation film 60 is formed on the surface on the oblique side.
In the other prism portion 56, a light reflecting film 61 is formed on a surface related to the oblique side, and a surface related to the other side of the equal side is a light emitting surface. 62 are formed.

The pair of splitter units 53 and 54 will be described with reference to the cross-sectional shape shown in FIG. 7. When one splitter unit 53 is used as a reference, the other splitter unit 54 is turned upside down, that is, one splitter unit 53 is turned upside down. Are combined in a posture rotated 180 ° about the axis Y.

In this state, both splitter units 53,
Numeral 54 denotes a surface on which the polarization splitting films 60, 60 are formed, which are positioned on the respective isosceles of the columnar space 70 having a right-angled isosceles triangular cross section with the apex angle facing the light incident side. Symmetrical state. Then, the light incident surfaces 58, 58 of the splitter units 53, 54, respectively.
Are continuous in the vertical direction, and the light exit surface of the transmitted polarized light that passes through the polarization separation film 60 is also continuous.

Further, in this state, two of the light emission surfaces of the reflected polarized light in each of the two splitter units belonging to the adjacent pair and adjacent to each other are also in a continuous state. For example, focusing on one of the splitter units 53, a splitter unit adjacent to the other splitter unit 54 on the opposite side (this is a splitter unit of a pair adjacent to the pair to which the one splitter unit 53 belongs). It is the other splitter unit.) 5
4A, the light emitting surface is continuous in the vertical direction, and the polarization direction changing films 62 and 62A formed on the light emitting surface are integrally continuous.

The light reflecting film 61 in each of two splitter units belonging to an adjacent pair and adjacent to each other.
Are formed on each of the isosceles sides of the columnar space 71 having an isosceles triangular cross section at right angles in cross section (for example, the light reflecting film 61 of one of the splitter units 53 and the light reflecting film 61A of the splitter unit 54A). It is located.

The above PBS array 50 is arranged such that its continuous light incident surface (58, 58) corresponds to the lens element 35 of the first lens plate 12. As shown in FIG. 6, the second lens plate 13 has a first lens element element 36a located corresponding to a continuous light exit surface of transmitted polarized light, and a second lens element 13a. The element 36b is arranged so as to be positioned corresponding to a continuous light exit surface of the reflected polarized light, that is, a continuous polarization direction changing film (for example, 62, 62A).

In the configuration of the PBS array 50 of the above-described separation plane symmetric type, the columnar space 70 having an isosceles cross section of the paired splitter units 53 and 54 and the isosceles triangle of the adjacent pair (53, 54A). Column space 7
1 may be optically left as a space, but in fact, from the viewpoint of mechanical strength and handling, the columnar space 70,
It is preferable that a transparent optical member having a cross-sectional shape corresponding to 71 is arranged and configured as a single unit as a whole.

According to the separation plane symmetric type PBS array 50 as described above, the light incident surface of the PBS element 51 constituted by the pair of splitter units 53 and 54 is the light incident surface of each splitter unit 53 and 54. 58, 58, and the thickness t in the system optical axis X direction is
It is の of the height H of the light incident surface of the element 51. And
In the configuration of the PBS array 20 of the separation plane parallel type shown in FIGS. 2 to 4, when the height of the light incident surface 28 is H, the thickness t is equal to H. In the PBS array 50 of the separation plane symmetric type, the same size H
Since the thickness t can be reduced to half while obtaining the light incident surface of, the effect of miniaturization is extremely large. Further, according to the above configuration, the variation of the angle component of the incident light is halved as compared with the case where the polarization separation film whose polarization separation ability depends on the incident angle. As a result, a higher light utilization rate can be realized.

This principle is explained as follows. That is, FIG. 8A shows an isosceles triangle 75 corresponding to the PBS element 21 of the PBS array 20 of the separation plane parallel type, and the polarization separation film 30 is formed on the oblique side. Here, the height h and the thickness d of the PBS element 21 correspond to two equal sides of the isosceles triangle 75, and therefore have the same size as a matter of course.

On the other hand, the configuration of the PBS array 50 of the separation plane symmetric type shown in FIGS. 6 and 7 is as shown in FIG. 8B, and isosceles triangle of FIG. 8A. 7
5 of the two isosceles triangles 76 and 77 formed when they are bisected by a perpendicular drawn down to the hypotenuse from the apex angle of the hypotenuse extending in the direction perpendicular to the optical axis direction (vertical direction in the figure). Has one isosceles triangle 76. The hypotenuse of this isosceles triangle 76 is height h and isosceles triangle 7
5 and the total area of the polarization separation films 60 and 60 is the same, but it is clear that the thickness in the optical axis direction is half (d / 2) of the case of the isosceles triangle 75.

As described above, according to the PBS array 50 of the separation plane symmetric type, the thickness is small with respect to the aperture area, so that it is extremely useful as the PBS array in the polarized light illuminating device having the above-described configuration. The miniaturization can be remarkably achieved. That is, not only the thickness of the PBS array is reduced, but also the diffusion area of light is suppressed, so that the aperture area of the second lens plate 13, the condenser lens 14, the projection lens, and the like is reduced. can do.

As described above, the polarized light illuminating apparatus of the present invention has been described in the case of using a parallel-separated plane type or a symmetrical separated plane type as a PBS array.
The extending direction of the PBS element 21 or 51 in the BS array 20 or 50 is
It is important to arrange the PBS array 20 or 50 so as to match the direction in which the image of the elongated light emitting unit 10 projected to zero extends.

That is, regardless of the type of the above-mentioned PBS array, its function is basically exerted by arranging it along a plane perpendicular to the system optical axis X. Each of the PBS arrays 20 and 50 is formed of a stack of columnar prisms having a parallelogram cross section, and the light incident surface does not extend over the entire PBS array, but in the stacking direction (shown in the figure). In the vertical direction in each example), the light incident surface and the non-optical path space 41
And the non-incident surfaces according to the above are alternately arranged, so that the processing characteristics are different between the stacking direction and the direction perpendicular to the stacking direction.

On the other hand, the light emitting section 10 is usually formed by a short arc lamp such as a metal halide lamp or a mercury lamp. In the short arc lamp, since the arc generated is elongated between the electrodes, the light emitting section 10 is formed. The image of the elongated light emitting unit 10 itself becomes an elongated shape.
The image of the lens element 35 is processed by the PBS array 20 or 50.

Therefore, in the arrangement of the PBS array 20 or 50, each PBS element 21 or 51 is
It is important to set the posture to extend in the same direction in relation to 0. According to such a configuration, the light emitting portion 10 projected from the lens element 35 of the first lens plate 12 is elongated. Since the image can be incident on the corresponding PBS element 21 or 51 while keeping the whole of the image in a continuous state, very little light is sacrificed.

On the other hand, if the direction in which the elongated image of the light emitting unit 10 projected on the PBS array 20 or 50 extends is the same as that of the PBS element 21 of the PBS array 20 or 50,
Or, when perpendicular to the direction in which 51 extends (in FIG. 2,
In the case where the image of the light emitting unit 10 extends in the vertical direction), a part of the image is incident in a cut state, so that a part of the light is sacrificed.

[0060]

According to the first aspect of the present invention, the polarizing beam splitter array having a specific configuration is used to form an optical path between the first lens plate and the second lens plate which forms an integrator optical system together with the first lens plate. Since the polarizing beam splitter array is arranged inside the polarizing beam splitter array, a small-diameter polarizing beam splitter array can be used, and as a result, a small polarized light illuminating device can be provided which basically has a high light utilization rate.

According to the second aspect of the present invention, since the polarizing beam splitter array is disposed immediately before the second lens plate, the effect of miniaturizing the apparatus can be reliably obtained.

According to the third aspect of the present invention, the ratio t / of the thickness t in the system optical axis direction of the polarizing beam splitter array to the distance L between the first lens plate and the second lens plate. Since the value of L is 0.2 or less, it is possible to provide a polarized light illuminating device that achieves miniaturization and does not sacrifice the light utilization rate.

According to the fourth aspect of the present invention, in the configuration using the PBS array of the separation plane parallel type, reflection is performed by utilizing the non-optical path space between the optical paths formed by the lens elements of the first lens plate. Since the member for processing the polarized light is disposed, the utilization of light can be reliably increased, and at the same time, the size of the apparatus can be significantly reduced.

According to the fifth and sixth aspects of the present invention, the above-described effects can be reliably obtained in a configuration using a PBS array having a parallel separation plane.

According to the seventh aspect of the present invention, it is possible to obtain a large light incident surface and to provide a split plane symmetric polarizing beam splitter array whose thickness is extremely small.

According to the eighth aspect of the present invention, it is possible to provide a split plane symmetric polarizing beam splitter array having a large light incident surface, a small thickness, and a polarization direction changing means. .

According to the ninth aspect of the present invention, it is possible to provide a polarization illuminating device that is small in size as a whole by using a PBS array having a symmetrical separation plane.

According to the tenth aspect, it is possible to provide the polarized light illuminating apparatus according to the ninth aspect, wherein the second lens plate has a simple configuration.

According to the eleventh aspect of the present invention, regardless of whether the PBS array is of the parallel-to-separation type or of the symmetrical type to the separation surface, the shape of the light emitting portion is taken into consideration, and the light utilization factor is also considered in that respect. Can be provided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a basic configuration of a polarized light illuminating device of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between a first lens plate and a second lens plate and a polarizing beam splitter array of a separation plane parallel type.

FIG. 3 is an explanatory cross-sectional view of a polarizing beam splitter array of a separation plane parallel type.

FIG. 4 is an explanatory diagram of a beam splitter element constituting a polarizing beam splitter array of a separation plane parallel type.

FIG. 5 is an explanatory cross-sectional view showing a modified example of the polarization beam splitter array of the separation plane parallel type in FIG.

FIG. 6 is a cross-sectional view for explaining a polarization plane splitter array of a separation plane symmetric type according to the present invention.

FIG. 7 is an explanatory diagram of a beam splitter element included in the separation plane symmetric polarization beam splitter array of FIG.

FIG. 8 is an explanatory view showing a beam splitter element constituting the split plane symmetric polarization beam splitter array of FIG. 7 in comparison with the case of a split plane parallel type.

FIG. 9 is an explanatory view showing a configuration of a conventional polarized light illumination device.

FIG. 10 is an explanatory sectional view showing a basic configuration of a liquid crystal display element.

[Explanation of symbols]

 X system optical axis 10 light emitting unit 11 converging concave reflecting mirror 12 first lens plate 13 second lens plate 14 condenser lens 15 liquid crystal display device 17 aperture regulating member 20 polarizing beam splitter array (PBS array) 21 beam splitter element ( PBS element) 22 Intermediate optical element 25, 26 Columnar prism portion 27 Boundary surface 28 Light incident surface 30 Polarization separation film 31 Light reflection film 32 Polarization direction changing film 33 Polarization direction changing film 35 Lens element 36a, 36b Lens element element PP polarization Light S S polarized light 40 Convergent light path 41 Non-optical path space 50 Polarized beam splitter array (PBS array) 51 Beam splitter element (PBS element) 53, 54, 54A A pair of splitter units 55, 56 Prism portion 57 Boundary surface 58 Light incidence Surface 60 Polarization separation film 6 , 61A Light reflecting film 62, 62A Polarization direction changing film 70, 71 Columnar space 75 Isosceles triangle 76, 77 Isosceles triangle 110 Light emitting unit 111 Concave reflecting mirror 112 First lens plate 113 Second lens plate 114 Condenser lens 115 Liquid crystal display element 120 Polarizing beam splitter LC Liquid crystal layer P1, P2 Polarizing plate 117 Diameter regulating member

Claims (11)

[Claims] A light source lamp; an optical system for converging light emitted from the light source lamp; a first lens plate including a plurality of lens elements disposed in an optical path of the converged light; A second lens plate comprising a plurality of lens elements corresponding to the lens elements of the first lens plate, which constitutes an integrator optical system together with the first lens plate; a first lens plate and a second lens plate And a polarization beam splitter array disposed in the optical path between the P-polarized light and the S-polarized light, and the polarization direction changing means for aligning one polarization direction of the separated P-polarized light and S-polarized light with the other polarization direction. The polarizing beam splitter array separates the irregularly polarized light incident from one surface into two types of linearly polarized light, P-polarized light and S-polarized light, and separates the two types of polarized light from a light exit surface adjacent to each other on the other surface. A plurality of beam splitter elements having a function of emitting light are arranged in a line, and polarized light emitted from each lens element of the second lens plate and having a uniform polarization direction is displayed on a liquid crystal display. A polarized light illuminating device characterized by being superimposedly illuminated on an object to be irradiated through an element. 2. The polarization beam splitter array according to claim 2, wherein
The polarization illuminating device according to claim 1, wherein the polarizing illuminating device is disposed immediately before the lens plate. 3. The value of the ratio t / L of the thickness t in the system optical axis direction of the polarizing beam splitter array to the distance L between the first lens plate and the second lens plate is 0.2.
The polarized light illuminating device according to claim 2, wherein: 4. The polarizing beam splitter array is a plate-like body in which a plurality of beam splitter elements are arranged along a plane perpendicular to the system optical axis, corresponding to the lens elements of the first lens plate. Each of the elements is an overall cross section in a state where two of the prismatic prism portions having a right-angled isosceles cross section are overlapped so that one of the equal sides of one of the prism portions coincides with one of the equal sides of the other prism portion. Is a parallelogram, and in one prism portion of each beam splitter element, a surface relating to the other of the equal sides is a light incident surface and a polarization separation film is formed on a surface relating to the oblique side thereof. In the other prism portion, the surface related to the oblique side is a light reflecting surface and the surface related to the other of the equal sides is a light emitting surface. Polarizing illumination device according to any one of claims 1 to 3. 5. A light-emitting surface for transmitted polarized light passing through the polarization splitting film of each beam splitter element and a light-emitting surface for reflected polarized light reflected by the polarization splitting film. The polarization illuminating device according to claim 4, wherein a polarization direction changing film constituting the polarization direction changing means is formed. 6. A second lens plate, comprising: a first lens element element disposed corresponding to a light exit surface of transmitted polarized light in each beam splitter element of the polarized beam splitter array; and a light exit of reflected polarized light. 6. The polarized light illuminating device according to claim 4, wherein the polarized light illuminating device is constituted by a second lens element element arranged corresponding to the surface. 7. A polarizing beam splitter array comprising a plurality of beam splitter elements stacked along one plane, wherein each of the beam splitter elements has a pair of splitter units stacked along the one plane. Each of the pair of splitter units overlaps two of the columnar prism portions having an isosceles triangular cross section at right angles so that one of the equal sides of one prism portion and one of the equal sides of the other prism portion coincide with each other. The entire cross section in the combined state forms a parallelogram, and in one prism portion, the surface on the other side of the equal side is a light incident surface and the surface on the oblique side is a polarization separation film. Is formed, and in the other prism portion, the surface related to the oblique side is a light reflecting surface and the surface related to the other of the equal sides is a light emitting surface. The pair of splitter units are characterized in that two of the light incident surfaces in each of them are in a continuous state, and the light emitting surfaces of the splitter units belonging to an adjacent pair and adjacent to each other are continuous. Polarization beam splitter array. 8. The polarization beam splitter according to claim 7, wherein a continuous polarization direction changing film is formed on a continuous light emission surface of the splitter unit belonging to an adjacent pair and adjacent to each other. array. 9. A polarizing beam splitter array according to claim 7, wherein a plane on which the plurality of beam splitter elements are superimposed is perpendicular to the system optical axis. 3. A continuous light incident surface formed by a pair of splitter units forming a pair is arranged corresponding to a lens element of the first lens plate.
Or the polarized light illuminating device according to claim 3. 10. A second lens plate, comprising: a first lens element element disposed corresponding to a continuous area of a light emission surface of transmitted polarized light in each beam splitter element of a polarized beam splitter array; 10. The polarized light illuminating device according to claim 9, comprising a second lens element element arranged corresponding to a continuous area of the light emitting surface of the light. 11. A light source lamp is constituted by a short arc lamp forming a rod-shaped light emitting portion, and a longitudinal direction of the light emitting portion with respect to an elongated image coincides with a length direction of each beam splitter element of the polarizing beam splitter array. The polarized light illuminating device according to any one of claims 4, 5, 6, 9, and 10.