JP2849238B2 - Single polarization wave conversion device and liquid crystal video projector device - Google Patents

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 any polarization direction into a single polarization wave, and enlarges a video signal on a screen using a matrix type liquid crystal panel. The present invention relates to a liquid crystal video projector for projecting.

[0002]

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

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

When parallel light having any polarization direction enters the polarization beam splitter 1, the polarization plane is divided into polarization waves (P polarization and S polarization) orthogonal to each other, the P polarization wave is transmitted, and the S polarization wave is incident. It is reflected at right angles to the optical axis (z-axis). When these polarized waves are emitted from the polarizing beam splitter 1, the P-polarized wave travels in the z-axis direction with the x-axis as the polarization direction, and the S-polarized wave travels in the y-axis, due to the positional relationship of the polarization layers. It advances in the x-axis direction while maintaining the direction.

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

[0006] Thus, the two polarized waves separated by the polarization beam splitter 1 both have the same polarization direction and have the same traveling direction. However, the combining prism 6,
At the time of incidence of 7, the light beam cross section has a rectangular shape of r × 2r. Therefore, the optical axes of the two polarized waves are tilted by refraction using the combining prisms 6 and 7, and the cross section of the emitted light beam 9
Are combined into a square shape of r × r equal to the incident light flux at the position of.

FIG. 3 shows the configuration 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 light from the light source 10 into S-polarized light and P-polarized light, 12 and 13 are total reflection mirrors, and 14 and 1
5 is a liquid crystal panel, 16 and 17 are polarizing plates, 18 is a polarizing plate 1
A polarizing beam splitter for synthesizing outgoing lights emitted from 6, 6 and 17 is a projection lens for enlarging and projecting.

Next, the operation will be described. In FIG. 3, light emitted from a light source 10 is divided by a polarization splitter 11 into polarized waves (S-polarized light and P-polarized light) whose polarization planes are orthogonal to each other. The polarization beam splitter 11 has a property of transmitting a P-polarized wave in incident light and reflecting an S-polarized wave, and basically has little 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 a 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 an S-polarized wave.

The relationship between the liquid crystal panel 14 and the polarizer 16 and the incident polarized wave (in this case, the P-polarized wave) is as shown in FIG. In the figure, reference numerals 14a and 14c denote glass plates;
b is a liquid crystal, the orientation direction of the incident side of the liquid crystal 14b coincides with the polarization direction of the incident light, gradually twists toward the emission side, and the orientation direction on the emission side is π / 2 ( rad
) The structure shall be twisted. In addition, they are arranged so that the alignment direction on the emission side and the polarization direction of the polarizing plate 16 match. Therefore, when the P-polarized wave is incident, and when the electric field is turned off, FIG.
As shown in FIG. 4A, the light is transmitted as an S-polarized wave, and is cut off 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 controlled.
5 and a second optical modulation system including the polarizing plate 17 perform optical modulation.

The S-polarized wave from the first optical modulation system and the second
Is input to the polarization beam splitter 18, the P-polarized wave is transmitted, and the S-polarized wave is reflected, and the light from the first and second optical modulation systems is combined and projected. The image is enlarged and projected by the lens 19.

In the above-mentioned conventional apparatus, the light from the light source is once separated into P and S polarized waves by the polarization beam splitters 11 and 18 and then combined to improve the light use 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 placed on the entrance sides of 4, 15
As a result, since the polarized wave on one side is discarded, the light utilization rate is 5%.
This is because it is difficult to increase the luminance due to the problem of heat resistance of the polarizing plate.

[0012]

The conventional single-polarization wave-forming device is constructed as described above, and requires a large space volume as an optical path and uses a large number of optical components. Weight and cost increased. In addition, since the optical axes are inclined by the combining prisms 6 and 7 for combining, there is a problem that the optical axes of the combined polarized waves do not completely match.

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

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and can reduce the volume, weight, and cost of an optical path while securing the conventional light utilization rate.
It is another object of the present invention to obtain a single polarized wave converting device that can make the optical axis of the emitted polarized wave in a single direction.

Further, the present invention provides a liquid crystal video projector capable of reducing the optical path volume, weight, and cost while maintaining the same light utilization rate as the conventional one, and improving the peripheral light amount difference of the projected image. The purpose is to gain.

[0016]

According to the present invention, there is provided a single-polarization wave-forming apparatus comprising four prisms each having a polarizing layer and a mirror surface formed on a boundary surface and having four light-exit surfaces except a light input / output surface. A total reflection mirror is attached. Further, the single polarized wave converting device according to the present invention is such that a prism having a mirror surface is attached in the same positional relationship instead of the total reflection mirror.

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 polarized wave, a liquid crystal panel for optically modulating the emitted light by a video signal, A projection lens for enlarging and projecting an image formed by a liquid crystal panel is provided.

[0018]

According to 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 mirror surfaces inside and outside the cubic prism combination, and the polarization direction is π. / 2 rad, and is emitted as a P-polarized wave.

In the present invention, the light from the light source is converted into a single polarized wave, 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. FIG.
Shows the configuration of a single polarization wave converting 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 its 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 a right-angled isosceles triangle as a bottom surface, and have a triangular prism shape whose height is equal to the length of a side sandwiching the right angle of the bottom surface. Polarizing layers 30 and 31 are formed on each boundary surface. This is shown in FIG. That is, the polarizing layer 3 is formed on a plane formed by one side sandwiching the right angle of the bottom surface and a corner 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 a direction perpendicular to the incident optical axis. Further, the inclined surfaces of the triangular prism-shaped prism combination bodies 20, 21 and 22, 23 are combined to form a cubic shape, and a mirror surface 32 of total reflection is formed in a portion where the prisms 20, 22 contact each other in both directions.

The above cubic prism combination bodies 20-2
Out of the six surfaces 3, the surface in contact with the two polarizing layers 30, 31 at the sides is defined as a light incident surface, and the surface in contact with each of the polarizing layers 30, 31 at a point is defined as a light emitting surface. As shown in FIG. 6, the two sides of the other four planes where the polarizing layers 30 and 31 traverse in the diagonal direction each have a base (length R) that is in contact with the light incident plane.
Then, first isosceles triangular total reflection mirrors 24 and 27 having a height of √2R / 2 are attached at an inclination of π / 4 rad with the mirror surfaces as inner surfaces. On the other two surfaces, a second isosceles triangular-shaped total reflection mirror is formed on the same side as the first isosceles triangular-shaped total reflection mirror, with the side where the pair of triangular prism-shaped prisms 20, 21 and 22, 23 contacts each other as the base. Reflection mirrors 25 and 28 are attached, and the third isosceles triangular total reflection mirror 26 having a height of R / 2 with the diagonal line being the base (length 長 2R).
29 is attached with its mirror surface facing the light emitting surface 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. Reference numeral 33 denotes a section of incident light, and reference numeral 34 denotes a section of output light. FIG. 9 is a diagram in which these sections are viewed from the optical axis direction on the incident side.
To D and A 'to D'. In FIGS. 7 and 8, unnecessary hidden lines are omitted in order to prevent the drawings from being complicated. Further, for the sake of description, axes orthogonal to each other are assumed between the incident optical axis and the light incident surface. That is, the x-axis direction and the y-axis direction are taken in parallel with two adjacent sides of the square light incident surface (equivalent to 33), and the incident optical axis is defined as the z-axis direction.

FIG. 7 is an explanatory view of the section A of the incident light 33. The polarizing layer 3 on the boundary between the prisms 20 and 21 is shown in FIG.
At 0, the P-polarized wave of the incident light is transmitted, 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
Reflected in the axial direction, travels in the x-axis direction as the polarization direction,
Subsequently, the light is reflected on the mirror surface 32 at the boundary between the prisms 20 and 22 in the x-axis direction and travels with the y-axis direction as the polarization direction, and further reflected on the total reflection mirror 24 in the z-axis direction and emitted with the y-axis direction as the polarization direction. Then, the light reaches the section A 'of the emitted light 34. The outgoing light 34 has a polarization direction of π /
It rotates by 2 rad and becomes a P-polarized wave. The section C of the incident light 33 is completely the same as that of the section A due to the symmetry of the apparatus, and the description thereof is omitted. However, the sections C and C ′ of the outgoing light 34 are polarized in the y-axis direction (P-polarized light in this example). ).

FIG. 8 is an explanatory diagram of the section B of the incident light 33. The P-polarized wave of the incident light is
1, 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
Reflected in the axial direction, travels in 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, travels 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. Outgoing light 3 as a P-polarized wave
4 to the section B '. The section D of the incident light 33 is completely the same as that of the section B due to the symmetry of the apparatus, and therefore the description is omitted. It is emitted as P-polarized light in the example.

As described above, a parallel light beam having any polarization direction is converted into a parallel light beam having a single polarization direction. Also, assuming that the cross section of the emitted light beam is equal to that of the conventional device,
The relationship of r = √2R is established. However, at this time, in order to make the light quantity of the outgoing light beam equal to that in the conventional case, it goes without saying that the cross-sectional area of the incident light beam is set to half of the conventional one and the density is doubled.

Embodiment 2 In the above embodiment, the total reflection mirrors 24 to 29 are mounted on the side surfaces of the assembly of the prisms 20 to 23. However, in Embodiment 2, as shown in FIG. Therefore, prisms 35 to 38 having mirror surfaces are attached to the surfaces having the same positional relationship as those described above, and the same effects as those of the first embodiment can be obtained.

In the above embodiments, a mirror or a mirror surface is used for the description. However, any mirror having a highly efficient optical reflecting surface can be used.

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

Next, the operation will be described. The light from the light source 10 has a larger amount of light at the center than at the periphery. FIG. 12A shows this state in a horizontal manner by the light amount difference distribution. The single polarized wave converter 39 transmits the P-polarized wave as described above, moves the S-polarized wave, and emits it as a P-polarized wave. At this time, since the peak of the light amount of the S-polarized wave comes to a corner of the distribution of the emitted light wave, the distribution of the emitted light difference becomes a state in which the periphery is lifted as shown in FIG. It is possible to alleviate a decrease in peripheral light amount due to vignetting. Accordingly, the light emitted from the light source 10 becomes a single polarized wave by the single polarized wave converting 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.

Although the above embodiment does not refer to color display, it does not mention a single 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. 39, a method in which the emitted light is color-separated and optically modulated for each color light by a plurality of monochrome liquid crystal panels and then combined, or a plurality of single polarization wave converting devices 39 and a monochrome liquid crystal panel are arranged after the light source light is color-separated. However, the same effect can be obtained for a system in which the light is modulated for each color light and then combined.

Fourth Embodiment In the third embodiment, the total reflection mirrors 24 to 29 are mounted. In the fourth embodiment, as shown in FIG.
Instead of 29, prisms 35 to 38 having mirror surfaces are attached to the surfaces having the same positional relationship as those described above, and the same effect as in the third embodiment can be obtained.

[0032]

As described above, according to the present invention, the light-emitting device is formed by the cubic prism combination and the mirror surface provided outside thereof, so that the optical path volume, weight, and cost can be reduced, and the polarization wave can be reduced. The optical axis can be unidirectional.

Further, according to the present invention, since the light source light is converted into a single polarized wave through the single polarization wave converting device, optical components such as a polarization beam splitter are not required, and the light source light beam cross-sectional area is reduced to half. Thus, the optical path space, the light source volume, the weight, and the cost can be reduced while maintaining the light utilization rate, and the decrease in the peripheral light amount of the projected image can be improved.

[Brief description of the 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 a diagram illustrating the operation of a conventional liquid crystal video projector device.

FIG. 5 is an explanatory diagram of a configuration of a prism portion of the single polarization wave converting device according to the present invention.

FIG. 6 is a perspective view and a front view of a mirror section of the single polarization wave conversion device according to the present invention.

FIG. 7 is a diagram illustrating the operation of the single polarization wave conversion device according to the present invention with respect to the incident light A region.

FIG. 8 is a diagram illustrating the operation of the single-polarization wave conversion device according to the present invention with respect to the incident light B region.

FIG. 9 is a sectional view of incident light and outgoing 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 a diagram showing the distribution of the difference between the input and output light amounts of the liquid crystal video projector device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Light source 14 Liquid crystal panel 19 Projection lens 20-23,35-38 Prism 24-29 Total reflection mirror 30,31 Polarization layer 32 Mirror surface 33 Incident light 34 Outgoing light 39 Single polarization wave conversion device

Claims (4)

(57) [Claims] 1. A triangular prism having a base of a right-angled isosceles triangle and a height equal to the length of a side sandwiching the right angle of the bottom surface, one side sandwiching the right angle of one bottom surface and an angle not on a surface in contact with the one side. A polarizing layer is formed on the plane to be formed, and a common side surface of a pair of triangular prisms is 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 at a portion where the two surfaces are in contact with each other, and a surface that is in contact with two polarizing layers on the sides of the six surfaces of the cubic prism combination is a light incident surface, and a surface that is in contact with each polarizing layer at a point is a light emitting surface. , The two surfaces of the other four surfaces that the polarizing layer traverses in the diagonal direction have the sides that are in contact with the light incident surface as bases, and the height is Δ
A 2 / 2-fold first isosceles triangular total reflection mirror is attached with its mirror surface as the inner surface at an inclination of π / 4 rad. A second isosceles triangular total reflection mirror is attached in the same relation as the isosceles triangular total reflection mirror, and a third diagonal line whose base is the base and whose height is.
Characterized in that the isosceles triangular total reflection mirror is mounted with its mirror surface facing the light emitting 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 device. 2. A prism having mirror surfaces in the same positional relationship instead of the total reflection mirrors is attached to four surfaces other than the light incident surface and the light reflection surface of the cubic prism combined body. Item 2. A single polarization wave-forming device according to Item 1. 3. A single polarization wave converting device that converts light from a light source into a single polarization wave, a liquid crystal panel that optically modulates light from the single polarization wave converting 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-forming device has a right-angled isosceles triangle as a base and a height equal to the length of one side sandwiching the right-angle of the bottom. A polarizing layer is formed on a plane formed by one side sandwiching the right angle of the bottom surface of the bottom and a corner not on the surface in contact with it, and the common side surfaces of a pair of triangular prisms are combined to form a cubic prism combined body , Forming a total reflection mirror surface where the tetrahedral pieces separated by the polarizing layer of each triangular prism contact each other,
Of the six faces of the cubic prism assembly, the face that contacts two polarizing layers on the sides is a light incident face, the face that contacts each polarizing layer at a point is a light emitting face, and the polarizing layer of the other four faces is Is a first isosceles triangular total reflection mirror whose sides are in contact with the light incident surface on the two diagonally crossing surfaces and whose height is √ / 2 times the height thereof. The second two isosceles triangular total reflection mirrors are attached to the remaining two surfaces in the same relation as the first isosceles triangular total reflection mirror, with the sides where the pair of triangular prisms contact each other as the bases. A third isosceles triangular total reflection mirror whose diagonal is the base and whose height is √2 / 4 times as large as that of the second surface and the second and third isosceles triangular total reflection mirrors, Liquid crystal display characterized by overlapping oblique sides on the light incident surface side Oh projector apparatus. 4. A prism having mirror surfaces in the same positional relationship instead of each of the total reflection mirrors is attached to four surfaces other than the light incident surface and the light reflection surface of the cubic prism combined body. Item 4. A liquid crystal video projector according to item 3.