JPH0527201A - Single polarized light wave generation device and video projector device - Google Patents

Abstract

PURPOSE:To set the optical axis of a projected polarized light wave to a single direction by reducing the optical path capacity, weight, and cost while maintaining a high light utilization rate. CONSTITUTION:Total reflecting mirrors 24-29 are fitted to four flanks of a cube, consisting of four prisms 20-23 having polarizing layers 30 and 31 and a mirror surface 32 on border surfaces, except a light incidence/projection surface, and incident light is split by the polarizing layers 30 and 31 into light beams which have mutually orthogonal planes of polarization; and the P polarized wave travels straight as it is and is projected and the S polarized light wave after being reflected by the polarizing layers 30 and 31 is reflected by the mirror surface 32 and total reflecting mirrors 24-29 to have its polarizing direction rotated by pi/2rad, so that the light is projected as a P polarized light wave.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single polarization wave converting device for converting parallel light having all polarization directions into a single polarization wave, and also enlarging a video signal on a screen by using a matrix type liquid crystal panel. The present invention relates to a liquid crystal video projector device for projecting.

[0002]

2. Description of the Related Art FIG. 2 is a perspective view of a generally known conventional single polarization wave conversion device, wherein 1 is a polarization beam splitter for separating parallel light having any polarization direction into S polarization and P polarization. ˜5 are right angle prisms, 6 and 7 are synthesizing prisms, 8 is incident light (cross section of the bundle), and 9 is outgoing light (cross section of the bundle).

Next, the operation will be described. First, FIG.
In the above, for the sake of description, axes that are orthogonal to each other are assumed between the light incident surface of the polarization beam splitter 1 and the incident optical axis. That is, in the x-axis direction parallel to the two adjacent sides of the light incident surface,
The y-axis direction is taken and the incident optical axis is the z-axis direction. The cross section 8 of the light beam incident on the polarization beam splitter 1 has the same square shape as the incident surface, and the length of one side is r.

When parallel light having all polarization directions is incident on the polarization beam splitter 1, it is divided into polarized waves (P-polarized light and S-polarized light) whose polarization planes are orthogonal to each other, the P-polarized wave is transmitted, and the S-polarized wave is incident. It is reflected at right angles to the optical axis (z axis). When these polarized waves are emitted from the polarization beam splitter 1, due to the positional relationship of the polarizing layers, the P polarized waves travel in the z axis direction with the x axis as the polarization direction, and the S polarized waves have the y axis as polarized light. Direction, while proceeding in the x-axis direction.

The P-polarized wave emitted from the polarization beam splitter 1 is reflected in the y-axis direction on the slope of the right-angle prism 2, travels with the x-axis as the polarization direction, and is then reflected in the x-axis direction on the slope of the right-angle prism 3. , Y-axis as the polarization direction and enters the combining prism 6. On the other hand, the S-polarized wave emitted from the polarization beam splitter 1 is reflected in the y-axis direction on the slope of the right-angle prism 4, travels with the x-axis as the polarization direction, and then is reflected in the x-axis direction on the slope of the right-angle prism 5, The light enters the combining prism 7 with the y axis as the polarization direction.

Thus, the two polarized waves separated by the polarization beam splitter 1 both have the same polarization direction and the traveling directions are the same. However, the synthesizing prism 6,
At the time of incidence of 7, the light beam cross section has a rectangular shape of r × 2r. Therefore, the synthesizing prisms 6 and 7 are used to incline the optical axes of the two polarized waves by refraction, and the outgoing light beam cross section 9
The light flux is combined into a square of r × r which is equal to the incident light flux at the position.

FIG. 3 shows the structure of a conventional liquid crystal video projector device, 10 is a light source for emitting white parallel light, and 11 is a light source.
Is a polarization beam splitter that separates the light from the light source 10 into S-polarized light and P-polarized light, 12 and 13 are total reflection mirrors, and 14
5 is a liquid crystal panel, 16 and 17 are polarizing plates, and 18 is a polarizing plate 1.
A polarization beam splitter that combines the outgoing lights emitted from the optical systems 6 and 17, and a projection lens 19 for enlarging and projecting.

Next, the operation will be described. In FIG. 3, the light emitted from the light source 10 is split by the polarization splitter 11 into polarized waves (S-polarized light, P-polarized light) whose polarization planes are orthogonal to each other. The polarization beam splitter 11 has the property of passing the P-polarized wave in the incident light and reflecting the S-polarized wave, and basically there is almost no loss here. The P-polarized wave emitted from the polarization beam splitter 11 is reflected by the total reflection mirror 12 and is incident on the liquid crystal panel 14 as the P-polarized wave. On the other hand, the S-polarized wave emitted from the polarization beam splitter 11 is reflected by the total reflection mirror 13 and enters the liquid crystal panel 15 as the S-polarized wave.

The relationship between the liquid crystal panel 14 and the polarizing plate 16 and the incident polarized wave (P polarized wave in this case) is as shown in FIG. In the figure, 14a and 14c are glass plates, 14
Reference numeral b denotes a liquid crystal, and the alignment direction on the incident side of the liquid crystal 14b coincides with the polarization direction of the incident light and gradually twists toward the emission side, and the alignment direction on the emission side is π / 2 (with respect to the incidence side. rad
) Use a twisted structure. Further, they are arranged so that the orientation direction on the output side and the polarization direction of the polarizing plate 16 coincide with each other. Therefore, when the P-polarized wave is incident, when the electric field is off, as shown in FIG.
As shown in FIG. 4A, the S-polarized light is transmitted, and when the electric field is on, it is blocked as shown in FIG. Similarly,
When the S-polarized wave passes through the liquid crystal panel 15 and the polarizing plate 17, the transmitted light becomes a P-polarized wave. Therefore, by controlling the electric field by the video signal, the first optical modulation system including the liquid crystal panel 14 and the polarizing plate 16 and the liquid crystal panel 1 are formed.
Optical modulation is performed in the second optical modulation system composed of the optical disc 5 and the polarizing plate 17.

The S-polarized wave from the first optical modulation system and the second
The P-polarized wave from the optical modulation system is incident on the polarization beam splitter 18, the P-polarized wave is transmitted and the S-polarized wave is reflected, and the lights from the first and second optical modulation systems are combined and projected. The image is enlarged and projected by the lens 19.

In the above-mentioned conventional apparatus, the light beams from the light source are once separated into P and S polarized waves by the polarization beam splitters 11 and 18 and then combined to improve the light utilization efficiency. is there. That is, when the light from the light source 10 is directly modulated by the optical modulation system, the liquid crystal panel 1
Polarizers must also be arranged on the incident side of 4, 15,
As a result, the polarized wave on one side is discarded, so the light utilization rate is 5
This is because it falls to 0%, and it is difficult to increase the brightness due to the problem of heat resistance of the polarizing plate.

[0012]

The conventional single polarization wave conversion device is configured as described above, and since the space volume required for the optical path is large and many optical parts are used, the volume of the entire device is Weight and cost have increased. Further, there is a problem that the optical axes of the combined polarized waves do not completely coincide because the optical axes are inclined by the combining prisms 6 and 7.

Further, the conventional liquid crystal video projector apparatus is configured as described above, and the light utilization rate is doubled as compared with the case where the light source light is directly modulated, but the spatial volume required as an optical path is increased. And the polarization beam splitter 11,
The use of optical components such as 18 added weight and cost.

The present invention has been made to solve the above problems, and can reduce the optical path volume, weight, and cost while ensuring the conventional light utilization rate.
Moreover, it is an object of the present invention to obtain a single polarization wave conversion device capable of directing the optical axis of the emitted polarization wave in a single direction.

Further, according to the present invention, there is provided a liquid crystal video projector device capable of reducing the optical path volume, weight and cost while ensuring the same utilization ratio of light as in the prior art and improving the peripheral light amount difference of the projected image. The purpose is to get.

[0016]

A single polarization wave conversion device according to the present invention has four side surfaces except a light input / output surface in a cube-shaped combination of four prisms having a polarizing layer and a mirror surface on the boundary surface. It is equipped with a total reflection mirror. Further, in the single polarization wave converting device according to the present invention, instead of the total reflection mirror, a prism having a mirror surface with the same positional relationship is attached.

Further, the liquid crystal video projector device according to the present invention comprises the above-mentioned single polarization wave converting device for converting light from a light source into a single polarization wave, and a liquid crystal panel for optically modulating the emitted light by a video signal. A projection lens for enlarging and projecting an image on the liquid crystal panel is provided.

[0018]

In the present invention, the P-polarized wave of the incident light is transmitted through the polarizing layer, the S-polarized wave is reflected by the polarizing layer, and further reflected by the mirror surface inside and outside the cubic prism combination, and the polarization direction is π. It is rotated by / 2 rad and emitted as a P-polarized wave.

Further, in the present invention, the light from the light source is converted into a single polarized wave, which is then optically modulated and enlarged and projected.

[0020]

【Example】

Embodiment 1 Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Figure 1
Shows the configuration of a single polarization wave conversion device according to this embodiment.
Reference numerals 0 to 23 are prisms, and reference numerals 24 to 29 are total reflection mirrors. The combined body of the prisms 20 to 23 forms a cube, and the side length is R. Further, the combined body of the prisms 20 and 21 and the combined body of the prisms 22 and 23 each have an isosceles right triangle as a bottom surface, and the height is a triangular column shape equal to the length of sides sandwiching the right angle of the bottom surface. Polarizing layers 30 and 31 are formed on the respective boundary surfaces. This state is shown in FIG. That is, the polarizing layer 3 is formed on a plane formed by one side that sandwiches the right angle of the bottom surface and a corner that is not on the surface in contact with this side.
0, 31 are formed. The polarizing layers 30 and 31 have an inclination of π / 4 rad with respect to the incident optical axis, and the S-polarized wave is reflected in the direction perpendicular to the incident optical axis. Further, the inclined surfaces of the triangular prism-shaped prism coupling bodies 20, 21 and 22, 23 are coupled to form a cubic shape, and a mirror surface 32 of total reflection in both directions is formed at a portion where the prisms 20 and 22 contact each other.

The above cube-shaped prism coupling bodies 20 to 2
Of the six surfaces of No. 3, the surface that is in contact with the two polarizing layers 30 and 31 at the side is a light incident surface, and the surface that is in contact with each of the polarizing layers 30 and 31 at a point is the light emitting surface. In addition, as shown in FIG. 6, the two surfaces of the other four surfaces which the polarization layers 30 and 31 cross in a diagonal direction are the bases (length R) which are in contact with the light incident surface.
Then, the first isosceles triangular total reflection mirrors 24 and 27 having a height of √2R / 2 are attached with an inclination of π / 4 rad with the mirror surface as the inner surface. In addition, on the other two surfaces, the second isosceles triangle-shaped total reflection mirror is used in the same relationship as the first isosceles triangular total reflection mirror with the sides in contact with the pair of triangular prisms 20, 21 and 22, 23 as the bases. The reflection mirrors 25 and 28 are mounted, and the third isosceles triangular total reflection mirror 26 having a diagonal of the bottom side (length √2R) and a height of R / 2,
29 is attached with its mirror surface facing the light emitting surface side at an inclination of π / 4 rad, and the oblique sides of the second and third isosceles triangular total reflection mirrors 25, 28, 26, 29 on the light incident surface side are overlapped.

Next, the operation will be described with reference to FIGS. 7 and 8. Reference numeral 33 indicates a section of incident light, and 34 indicates a section of emitted light. FIG. 9 is a view of these sections as seen from the optical axis direction on the incident side.
.About.D and A'.about.D 'are attached. Note that unnecessary hidden lines are omitted in FIGS. 7 and 8 to prevent the drawings from being complicated. For the sake of explanation, it is assumed that mutually orthogonal axes are provided between the incident optical axis and the light incident surface. That is, the x-axis direction and the y-axis direction are taken parallel to the two adjacent sides of the square light incident surface (equivalent to 33), and the incident optical axis is the z-axis direction.

FIG. 7 is an explanatory view of the section A of the incident light 33, and the polarizing layer 3 on the boundary surface between the prisms 20 and 21.
The P-polarized wave of the incident light of 0 is transmitted and is emitted in the z-axis direction as it is with the y-axis direction as the polarization direction and reaches the section A of the emitted light 34. On the other hand, the S polarized wave is y in the polarizing layer 30.
It is reflected in the axial direction and travels with the x-axis direction as the polarization direction,
Subsequently, the light is reflected in the x-axis direction by the mirror surface 32 at the boundary between the prisms 20 and 22 and proceeds in the y-axis direction as the polarization direction, and further reflected in the z-axis direction by the total reflection mirror 24 and emitted in the y-axis direction as the polarization direction. The emitted light 34 reaches the section A ′. The outgoing light 34 has a polarization direction of π / due to two-time specular reflection.
It rotates by 2 rad and becomes a P-polarized wave. The section C of the incident light 33 is completely the same as the section A due to the symmetry of the device, and therefore the description thereof is omitted. However, the y-axis direction is the polarization direction (P polarized light in this example) for the sections C and C ′ of the outgoing light 34. ) Is emitted as.

FIG. 8 is an explanatory view of the section B of the incident light 33, in which the P-polarized wave of the incident light is the prisms 20 and 2.
The light passes through the polarizing layer 30 on the boundary surface of No. 1 and is emitted as it is in the z-axis direction with the y-axis direction as the polarization direction, and reaches the section B of the emitted light 34. On the other hand, the S polarized wave is y in the polarizing layer 30.
It is reflected in the axial direction and travels with the x-axis direction as the polarization direction,
The light passes through the prism 23, is reflected in the x-axis direction by the total reflection mirror 25, proceeds in the y-axis direction as the polarization direction, is further reflected in the z-axis direction by the total reflection mirror 26, and is emitted in the y-axis direction as the polarization direction. , Emitted light as P-polarized wave 3
4 to section B '. The section D of the incident light 33 is completely the same as the case of the section B due to the symmetry of the device, and therefore the description thereof will be omitted. It is emitted as P-polarized light in the example).

As described above, the parallel light beams having all the polarization directions are converted into the parallel light beams having the single polarization direction. Also, assuming that the outgoing light beam cross-sectional area is equal to that of the conventional device,
The relation of r = √2R is established. However, in this case, it is needless to say that the cross-sectional area of the incident light flux is halved and the density is doubled in order to make the light quantity of the emitted light flux equal to the conventional one.

Example 2 In the above example, the total reflection mirrors 24 to 29 were attached to the side surfaces of the aggregate of the prisms 20 to 23. However, as a second example, as shown in FIG. Therefore, the prisms 35 to 38 having mirror surfaces are attached to the surfaces having the same positional relationship as these, and the same effect as that of the first embodiment is obtained.

In each of the above embodiments, the mirror or the mirror surface is used for the sake of description, but any mirror having a highly efficient optical reflecting surface can be replaced.

Embodiment 3 FIG. 11 shows the configuration of a liquid crystal video projector device according to this embodiment, and 39 is the single polarization wave converting device described with reference to FIG. 1 and FIGS. It receives and emits a single polarized wave (here, P polarized wave). Other configurations are the same as the conventional one.

Next, the operation will be described. The light amount of the light source 10 is larger in the central portion than in the peripheral portion. FIG. 12A shows this state laterally by the light amount difference distribution. As described above, the single polarization wave converting device 39 transmits the P polarization wave, moves the S polarization wave, and emits the P polarization wave as the P polarization wave. At this time, since the light quantity peak of the S-polarized wave comes to a corner of the outgoing light quantity wave distribution, the outgoing light quantity difference distribution is in a state in which the periphery is raised as shown in FIG. 12B, and when the image is enlarged and projected. It is possible to mitigate the decrease in peripheral light amount due to vignetting. Therefore, the light emitted from the light source 10 becomes a single polarization wave by the single polarization wave conversion device 39, is optically modulated by the liquid crystal panel 14 and the polarizing plate 16, and is enlarged and projected by the projection lens 19.

In the above embodiment, although the color display is not mentioned, a system using a single plate color liquid crystal panel in which a color filter is formed for each pixel of the liquid crystal panel 14 or a single polarization wave conversion device is used. A method of color-separating the outgoing light of 39 and optically modulating each color light by a plurality of black-and-white liquid crystal panels, or a method of synthesizing the light, and a plurality of single polarization wave conversion devices 39 and a black-and-white liquid crystal panel after color-separating the light of the light source. However, the same effect can be obtained even in a system in which each color light is optically modulated and then combined.

Fourth Embodiment Although the total reflection mirrors 24 to 29 are attached in the third embodiment, as the fourth embodiment, as shown in FIG.
In place of 29, prisms 35 to 38 each having a mirror surface formed on a surface having the same positional relationship as these are mounted, and the same effect as that of the third embodiment can be obtained.

[0032]

As described above, according to the present invention, the cube-shaped prism coupling body and the mirror surface provided outside the cube-shaped prism coupling body are formed, so that the optical path volume, weight, and cost can be reduced, and the polarization wave The optical axis can be unidirectional.

Further, according to the present invention, since the light source light is made into a single polarized wave through the single polarization wave converting device, optical parts such as a polarization beam splitter are unnecessary, and the light source light beam cross-sectional area is halved. Therefore, it is possible to reduce the optical path space, the volume of the light source, the weight, and the cost while maintaining the light utilization rate, and it is possible to improve the reduction of the peripheral light amount of the projected image.

[Brief description of drawings]

FIG. 1 is a perspective view of a single polarization wave conversion device according to the present invention.

FIG. 2 is a perspective view of a conventional single polarization wave conversion device.

FIG. 3 is a configuration diagram of a conventional liquid crystal video projector device.

FIG. 4 is an operation explanatory diagram of a conventional liquid crystal video projector device.

FIG. 5 is a structural explanatory view of a prism portion of the single polarization wave conversion device according to the present invention.

6A and 6B are a perspective view and a front view of a mirror portion of a single polarization wave converting device according to the present invention.

FIG. 7 is an operation explanatory diagram of an incident light A region of the single polarization wave converting device according to the present invention.

FIG. 8 is an operation explanatory diagram for an incident light B region of the single polarization wave conversion device according to the present invention.

FIG. 9 is a sectional view of incident light and emitted light of the single polarization wave conversion device according to the present invention.

FIG. 10 is a perspective view of a single polarization wave conversion device according to another embodiment of the present invention.

FIG. 11 is a configuration diagram of a liquid crystal video projector device according to the present invention.

FIG. 12 is an input / output light amount difference distribution map of the liquid crystal video projector device according to the present invention.

[Explanation of symbols]

10 light sources 14 LCD panel 19 Projection lens 20-23, 35-38 Prism 24-29 Total reflection mirror 30,31 Polarizing layer 32 mirror surface 33 incident light 34 outgoing light 39 Single polarization wave conversion device

Claims (4)

[Claims] 1. An isosceles right triangle is used as a base, and a height of one side of a triangular prism having a height equal to the sides of the right side of the bottom is defined by one side of the right side of the bottom and a corner not on the surface in contact with the side. A polarizing layer is formed on the plane to be formed, and common side surfaces of a pair of triangular prisms are combined to form a cubic prism combined body, and tetrahedral pieces separated by the polarizing layer of each triangular prism are combined. A total reflection mirror surface is formed in a portion where is in contact with, and a surface which is in contact with two polarizing layers at two sides of the six surfaces of the cubic prism combined body is a light incident surface and a surface which is in point contact with each polarizing layer is a light emitting surface. Then, the two sides of the other four planes that the polarization layer crosses in a diagonal direction are the sides that are in contact with the light incident plane, and the height is √
The first isosceles triangular total reflection mirror of 2/2 times is attached with the mirror surface as the inner surface at an inclination of π / 4 rad, and the other two surfaces have the sides in contact with the pair of triangular prisms as the bases. A second isosceles triangular total reflection mirror is mounted in the same relationship as the isosceles triangular total reflection mirror, and a third line whose diagonal is the base is √2 / 4 times its height.
The isosceles triangular total reflection mirror is attached so that its mirror surface faces the light emission surface side, and the oblique sides of the second and third isosceles triangular total reflection mirrors on the light incident surface side are overlapped. One polarization wave converter. 2. A prism having a mirror surface in the same positional relationship is attached to each of the four surfaces other than the light incident surface and the light reflecting surface of the cubic prism assembly in place of the respective total reflection mirrors. Item 1. A single polarization wave conversion device according to item 1. 3. A single polarization wave conversion device for converting light from a light source into a single polarization wave, a liquid crystal panel for optically modulating the light from the single polarization conversion device with a video signal, and an image formed by the liquid crystal panel. In a liquid crystal video projector device equipped with a projection lens for enlarging and projecting, a single polarization wave conversion device has a base of a right-angled isosceles triangle and a height of one side of a triangular prism that is equal to the length of one side sandwiching the right angle of the bottom face. While forming a polarizing layer on a plane formed by one side sandwiching the right angle of the bottom surface of the base and a corner not on the surface in contact with it, common side surfaces of a pair of triangular prisms are combined to form a cubic prism combined body. , A total reflection mirror surface is formed at the portion where the tetrahedral pieces separated by the polarizing layer of each triangular prism contact.
Of the six faces of the cube-shaped prism combination, the face that is in contact with two polarizing layers at the side is the light incident face, and the face that is in point contact with each polarizing layer is the light emitting face, and the other of the four faces is the polarizing layer. Of the first isosceles triangular total reflection mirror whose base is the side in contact with the light incident surface and whose height is √2 / 2 times that of the two surfaces that intersect in the diagonal direction are π / 4 rad of which the mirror surface is the inner surface. The second isosceles triangular total reflection mirror is mounted in the same relationship as the first isosceles triangular total reflection mirror, with the sides contacting the pair of triangular prisms being the bottom sides on the remaining two surfaces. , A third isosceles triangle-shaped total reflection mirror having a diagonal line as a base and a height of √2 / 4 times that of the second side and a third isosceles triangle-shaped total reflection mirror. Liquid crystal display characterized by stacking hypotenuses on the light incident surface side Oh projector apparatus. 4. A prism having a mirror surface in the same positional relationship is mounted on each of the four surfaces other than the light incident surface and the light reflecting surface of the cubic prism combined body, instead of the respective total reflection mirrors. Item 3. A liquid crystal video projector device according to item 3.