KR100254335B1 - Lcd device - Google Patents

Abstract

Parallel light emitted from the lamp 1 generating white light and reflected by the reflector 2 enters the first hologram optical element 5. The first hologram optical element 5 splits parallel light into colored light components of a plurality of different wavelength bands and emits the light components. The light components emitted from the first hologram optical means 5 impinge on the second hologram optical element 6 at an angle of incidence different for each wavelength. The second hologram optical element 6 causes light of different wavelengths to be incident on each pixel of the liquid crystal device 7.

Description

LCD Display

BACKGROUND ART Liquid crystal display (LCD) devices are known which emit light from a back light source to a liquid crystal (LC) cell to display color images. This LCD device uses red (R), green (G), and blue (B) corresponding to the pixels of the LC cell.

When the light from the back light source passes through the color filter, the LCD device displays a color image.

However, when light from the back light source penetrates the color filters in this LCD device, the color filters absorb light of complementary color components. The LCD device therefore has a low utilization efficiency of light from the back light source and encloses a black color display.

In view of the above situation, an LCD device having improved light utilization efficiency using a holographic optical element has recently been developed. This LCD device has holographic optics installed between the light source and the LC cell. This holographic optic splits the light from the back light source into parallel light components of R, G and B wavelengths. The split light is collected on the pixel of the LC cell of the associated colors. Thus, light of individual wavelengths enters without waste into each pixel of the LC cell.

Each of the multiple diffraction gratings of the holographic optical element of this LCD device diffracts light of any wavelength among the wavelengths of parallel light incident (incidence angle) at arbitrary angles. Since different diffraction angles exist for different wavelengths of light, light at each wavelength enters the relevant pixel of the LC cell.

The diffraction angle and diffraction efficiency of this hologram optical element with respect to light of each wavelength are determined by the angle of incidence of light directed to the holographic optical element. Therefore, the intensity of light incident on each pixel of the LC cell is not fixed but varies with wavelength. Generally used hologram optical element has the highest diffraction efficiency for G wavelength among the R, G and B wavelength components. Therefore, it is not easy to achieve good color characteristics with balanced R, G, and B colors.

The present invention relates to a liquid crystal display device, and more particularly to a color liquid crystal display device using optical means such as a holographic optical element device.

1 is a side view illustrating the structure of an LC projector according to a first embodiment of the present invention;

FIG. 2 is a plot showing the light path for light of the green (G) wavelength component within the LC projector of FIG.

FIG. 3 is a plot showing the light path for light of the red (R) wavelength component within the LC projector of FIG.

4 is a chart showing the light path for light of the blue (B) wavelength component within the LC projector of FIG. 1;

5 is a graph showing the diffraction efficiency of the second hologram optical element of the LC projector;

6 is a diagram showing a variant of an LC projector first according to the first embodiment of the present invention;

7 is a diagram showing a variant of an LC projector second according to the first embodiment of the present invention;

8 is a cross-sectional view illustrating the structure of an LC projector according to a second embodiment of the present invention;

9 is a diagram showing a first variant of the LC projector according to the second embodiment of the present invention;

10 is a diagram showing a second variant of the LC projector according to the second embodiment of the present invention;

11 is a cross-sectional view illustrating the structure of an LC projector according to a third embodiment of the present invention;

FIG. 12 is a plot showing the light path for light of the green (G) wavelength component within the LC projector of FIG.

FIG. 13 is a plot showing the optical path to light of the red (R) wavelength component within the LC projector of FIG.

FIG. 14 is a plot showing the light path for light of the blue (B) wavelength component within the LC projector of FIG.

15 is a sectional view for explaining the structure of the LC projector according to the fourth embodiment of the present invention;

16 is a sectional view for explaining the structure of an LC projector according to a fifth embodiment of the present invention;

FIG. 17 is a plot showing the light path from the lamp to the pixels of the LC cell of FIG. 16;

18 is a diagram showing the shape of a microlens combined with unit pixels, and

19 is a diagram showing another shape of a microlens combined with unit pixels.

<Explanation of symbols for main parts of drawing>

1: lamp 2: reflector

3: optical axis 4: incident side polarizing plate

5,15,20,25,51: first optical means 6,16,21,26,50: second optical means

7: LC cell 8: exit side polarizer

9: projection lens

It is therefore an object of the present invention to provide an LCD device which can obtain good color characteristics with balanced R, G and B colors.

In order to achieve the above object, an LCD device according to an aspect of the present invention is:

Light sources 1, 2 for providing essentially parallel light fluxes;

An LC device 7 having multiple pixels;

First holographic optics 5, 15 for splitting essentially parallel light fluxes from light sources 1, 2 into light fluxes of a plurality of different wavelength bands and for emitting the split light fluxes in different directions ; And

A second hologram optical element 6, 16 for guiding light fluxes of a plurality of different wavelength bands emitted from the first hologram optical element 5, 15 to a predetermined pixel of the LC device 7 for each wavelength band; Include.

The light fluxes of a plurality of different wavelength bands split by the first hologram optics impinge on the second hologram optics at different incidence angles. The second hologram optic can thus make the intensity of the light components incident on each pixel of the LC cell essentially the same for any wavelength band.

Thus, this LCD device can obtain excellent color characteristics with balanced R, G and B colors.

An LCD device according to another aspect of the present invention is:

Light sources 1,2 for providing essentially parallel light fluxes;

An LC device 7 having multiple pixels;

Prisms 20 and 25 for splitting essentially parallel light fluxes from light sources 1 and 2 into light fluxes of multiple different wavelength bands and emitting the split light fluxes in different directions; And

Second hologram optics 21 and 26 for guiding light fluxes of a plurality of different wavelength bands emitted from the prisms 20 and 25 to predetermined pixels of the LC device 7 for each wavelength band.

Many different wavelength bands of light fluxes split by the prism impinge on the holographic optics at different angles of incidence. Therefore, the holographic optics can make the intensity of the light components incident on each pixel of the LC cell essentially the same for any wavelength band.

Thus, this LCD device can obtain excellent color characteristics with balanced R, G and B colors.

An LCD device according to another aspect of the present invention is:

Light sources 1,2 for providing essentially parallel light fluxes;

An LC device 7 having multiple pixels;

Hologram optics 51 for splitting essentially parallel light fluxes from light sources 1 and 2 into light fluxes of multiple different wavelength bands and for emitting the split light fluxes in different directions;

And a lens 50 for guiding light fluxes of a plurality of different wavelength bands emitted from the prisms 20 and 25 to predetermined pixels of the LC device 7 for each wavelength band.

Light fluxes of multiple different wavelength bands split by holographic optics enter the lens at different angles of incidence. Therefore, this lens can make the intensity of the light components incident on each pixel of the LC cell essentially the same for any wavelength band.

Thus, this LCD device can obtain excellent color characteristics with balanced R, G and B colors.

In other words, the LCD device according to the present invention is:

Light sources 1,2 for providing essentially parallel light fluxes;

An LC device 7 having multiple pixels;

First optical means (5, 15) for splitting essentially parallel light fluxes from light sources (1,2) into light fluxes of multiple different wavelength bands and for emitting the split light fluxes in different directions, respectively; 20, 25; 51) and

Second optical means 6 for guiding light fluxes of a plurality of different wavelength bands emitted from the first optical means 5, 15; 20, 25; 51 to the predetermined pixel of the LC device 7 for each wavelength band. , 16; 21, 25; 50).

[First Embodiment]

1 shows the structure of an LCD projector according to a first embodiment of the present invention.

In this LC projector, a lamp 1 for generating white light is provided at the focal point of the reflector 2 having a parabolic surface. The reflector 2 reflects the light from the lamp 1 to be parallel to the optical axis 3. The polarizing plate 4 which passes the light of a specific polarized light component is provided perpendicular to the optical axis 3 on the side which reflects the light of the reflector 2. (This polarizing plate 4 will hereinafter be referred to as "incident side polarizing plate.") The first hologram optical element 5 inclined to the optical axis 3 by a predetermined angle has the light of the incident side polarizing plate 4 It is arranged on the outgoing side. Therefore, the parallel light of the polarized specific light component of the incident side polarizing plate 4 enters the first hologram optical element 5 at a predetermined incident angle. On the side from which the light of the first hologram optical element 5 exits, the second hologram optical element 6 is provided in parallel with the first hologram optical element 5. On the side from which the light of the second hologram optical element 6 exits, the LC cell 7 is provided in parallel with the second hologram optical element 6. On the outgoing side of the LC cell 7, a polarizing plate 8 (hereinafter referred to as " output side polarizing plate ") for passing a specific polarized light component is provided in parallel to the LC cell 7. The projection lens 9 for projecting the image of the light passing through the exit side polarizing plate 8 is provided on the side from which the light of the exit side polarizing plate 8 exits.

The LC cell 7 is sealed between a pair of transparent substrates on which electrodes are formed in the form of a dot matrix, and multiple pixels are formed in the form of a dot matrix. The black matrix BM for preventing light leakage is provided between the pixels on the substrate where light is incident. The LC cell 7 has unit pixels each composed of a set of three color (R, G and B) pixels. One side of each pixel has a size of 54 mu m, and the pitch between the pixels is 88 mu m. However, this LC cell 7 has no color filter.

The incident side polarizing plate 4 passes a specific polarized light component (eg, one of linearly polarized S light or P light component) included in parallel light reflected by the reflector 2 generated from the lamp 1. The exit-side polarizer 8 passes certain polarized light components in the light exiting from the LC cell 7.

The first hologram optical element 5 diffracts light of an arbitrary wavelength with individual diffraction gratings. The diffraction angle of the light diffracted by the first hologram varies with the wavelength. The diffraction grating of the first hologram optical element 5 is formed with a uniform pitch d (= 2.182). The light of the three wavelength components R, G and B (hereinafter referred to as "light of the R wavelength component", "light of the G wavelength component" and "light of the B wavelength component") is the second hologram optical element 6 The first hologram optical element 5 is inclined at 23 ° to the optical axis 3 of the lamp 1 so as to be incident at each particular incident angle. Therefore, the incident angle of the light toward the first hologram optical element 5 is 23 degrees. The first hologram optical element 5 diffracts light incidence at an incidence angle of 23 ° in order to emit final light at an angle that varies with wavelength. Light of the R wavelength component (λ = 640 nm) is emitted at an angle of 43 ° from the first hologram optical element 5. Light of the G wavelength component (λ = 550 nm) is emitted at an angle of 40 degrees from the first hologram optical element 5. Light of the B wavelength component (λ = 460 nm) is emitted at an angle of 37 degrees from the first hologram optical element 5.

The second hologram optical element 6 diffracts light of any wavelength. The diffraction angle of the light diffracted by the second hologram optical element 6 depends on the wavelength. The second hologram optical element 6 enters each pixel of the LC cell in which light from the first hologram optical element 5 incident at a specific angle of incidence with respect to the individual wavelength components corresponds to the respective color. 2 to 4, the second hologram optical element 6 is arranged in combination with unit pixels each composed of three color (R, G and B) pixels of a set of LC cells 7. Unit hologram optics. Such unit hologram optics show the maximum diffraction efficiency for the R wavelength at points HA shown in Figures 2-4 and the maximum diffraction efficiency for the G wavelength at points HB shown in Figures 2-4 and at the point HC shown in Figures 2-4. It has the maximum diffraction efficiency for the B wavelength. Therefore, the diffraction grating pitch d _A at point HA is 1.006 nm, the diffraction grating pitch d _B at HB is 1.006 nm and the diffraction grating pitch d _C at HC is 1.006 nm. As shown in FIG. 5, the second hologram optical element 6 has a high diffraction efficiency of light of the G wavelength component when the light of each wavelength component is incident at an angle of incidence of 40 °. The diffraction efficiency of the light of the R wavelength component is high when it is incident and the diffraction efficiency of the light of the B wavelength component is high when the light of each wavelength component is incident at an incident angle of 37 degrees.

The second holographic optical element 6 is arranged at intervals of about 10 mu m with the first holographic optical element. In the second hologram optical element 6, light incidence is arranged at intervals of about 1100 mu m with respect to the surface of the LC cell 7.

The operation of this LC projector will now be described.

As shown in FIG. 1, the light from the lamp 1 in the LC projector is reflected by the reflector 2 to be parallel to the optical axis 3. This parallel light is incident perpendicularly to the incidence side polarizer 4 which selectively passes the light of a particular polarized light component. Light of the specific polarized light component selected by the incident side polarizer 4 enters the first hologram optical element 5 at an incidence angle of 23 °. As shown in Figs. 2 to 4, the light of the R, G and B wavelength components incident on the first hologram optical element 5 is diffracted by the first hologram optical element 5 at different diffraction angles and further Exit at each exit angle. Light leaving the first optical element 5 enters the second hologram optical element 6 at an optimal angle of incidence for each wavelength component. Light of each wavelength component incident on the second hologram optical element 6 is focused on an associated pixel of the LC cell 7 corresponding to each color.

This will be discussed in detail below for each of the R, G and B wavelength components.

As shown in FIG. 2, the light of the G wavelength component incident on the first hologram optical element 5 at an incidence angle of 23 ° is diffracted and exits from the first hologram optical element 5 at an exit angle of 40 °. The light leaving the first holographic optical element 5 enters the second holographic optical element 6 at an incident angle of 40 degrees. Light entering the point HB of the second hologram optical element 6 leaves the second hologram optical element 6 at substantially right angles and strikes the relevant pixel for G of the LC cell 7. Light incident on the point HA of the second hologram optical element 6 leaves the second hologram optical element 6 at a predetermined exit angle and hits the relevant pixel for G of the LC cell 7. Light incident on the point HC of the second hologram optical element 6 leaves the second hologram optical element 6 at a predetermined exit angle and strikes the associated pixel for G of the LC cell 7.

As shown in Fig. 3, the light of the R wavelength component incident on the first hologram optical element 5 at an incidence angle of 23 ° is diffracted and exits from the first hologram optical element 5 at an exit angle of 43 °. Light leaving the first hologram optical element 6 enters the second hologram optical element 6 at an incident angle of 43 °. Light incident on the point HA of the second hologram optical element 6 leaves the second hologram optical element 6 at substantially right angles and strikes the relevant pixel for R of the LC cell 7. Light incident on the point HB of the second hologram optical element 6 leaves the second hologram optical element 6 at a predetermined exit angle and strikes the associated pixel for R of the LC cell 7. Light incident on the point HC of the second hologram optical element 6 leaves the second hologram optical element 6 at a predetermined exit angle and strikes the relevant pixel for R of the LC cell 7.

As shown in Fig. 4, the light of the B wavelength component incident on the first hologram optical element 5 at an incidence angle of 23 ° is diffracted and exits from the first hologram optical element 5 at an exit angle of 37 °. Light leaving the first hologram optical element 6 enters the second hologram optical element 6 at an incidence angle of 37 degrees. Light entering the point HC of the second hologram optical element 6 leaves the second hologram optical element 6 at substantially right angles and hits the relevant pixel for B of the LC cell 7. Light incident on the point HB of the second hologram optical element 6 leaves the second hologram optical element 6 at a predetermined exit angle and strikes the associated pixel for B of the LC cell 7. Light incident on the point HA of the second hologram optical element 6 leaves the second hologram optical element 6 at a predetermined exit angle and strikes the associated pixel for B of the LC cell 7.

As described above, according to this LC projector, the parallel light emitted from the lamp 1 and reflected by the reflector 2 is diffracted by the first hologram optical element 5 at different diffraction angles for each wavelength. do. That is, the exiting light of each wavelength component from the first hologram optical element 5 enters the second hologram optical element 6 at an optimum angle of incidence. Therefore, it is possible to improve the diffraction efficiency of light of each wavelength component by the second hologram optical element 6. That is, the second hologram optical element 6 can efficiently concentrate the light of each wavelength component with respect to the associated color to the associated pixel of the LC cell. The light of each wavelength component that has passed through the exit-side polarizing plate 8 of the LC cell 7 is projected by the projection lens 9 as an arbitrary image. As a result, a clear and bright projected image is obtained.

In the above, only the optical path for the R wavelength component (λ = 640 nm), the optical path for the G wavelength component (λ = 550 nm) and the optical path for the B wavelength component (λ = 460 nm) have been discussed. The wavelength of the light emitted from the lamp 1 is not limited to those three.

For example, light of all wavelength components between the R and G wavelength components exits the first hologram optical element 5 at an exit angle of 40 ° to 43 °. The exiting light from the first hologram optical element 5 is diffracted by the second hologram optical element 6. The exiting light from the second hologram optical element 6 is directed to any pixel for R in the LC cell 7, black matrix BM and any pixel for G in the LC cell 7, depending on the wavelength. Enter In other words, light of a given wavelength band around the R wavelength component enters a certain pixel for R of the LC cell 7, and light of a given wavelength band around the G wavelength component is directed to G of the LC cell 7. Into which pixel to go.

Yellow light, which also does not belong to the band, is absorbed by the black matrix (BM). Therefore, even if the LC cell 7 has no color filter, the color of the light leaving the LC cell 7 does not become ambiguous.

Although the LC projector has the first and second holographic optics 5, 6 arranged side by side, the arrangement will not be limited to this particular type but will have the form shown in Figures 6 and 7.

In the first variant shown in Fig. 6, the transparent plate 10 made of glass or the like is arranged on the side from which the light of the incident side polarizing plate 4 inclined at a predetermined angle (23 °) with respect to the optical axis 3 exits. The first hologram optical element 5 is provided on the light-incident surface of this transparent plate 10 and the second hologram optical element 6 is provided on the light-exciting surface of the transparent plate 10.

In the second modification shown in FIG. 7, the transparent plate 10 made of glass or the like is arranged on the side from which the light of the incident side polarizing plate 4 inclined at a predetermined angle (23 °) with respect to the optical axis 3 is emitted. The second hologram optical element 6 is provided on the light-extracting surface of the transparent plate 10 and the first hologram optical element 5 is installed on the light-extracting surface of the first hologram optical element 5. do.

The LC projector according to the first and second variants has substantially the same functions and advantages as the LC projector of the first embodiment.

Second Embodiment

8 is a cross-sectional view for explaining the structure of an LCD projector according to a second embodiment of the present invention. In order to avoid undue description, similar or identical reference numerals are given to the components of the present embodiment that are identical to the relevant components of the first embodiment.

The incident side polarizing plate 4 is provided on the side which reflects the light of the reflector 2 which reflects the light from the lamp 1 in parallel to the optical axis 3 perpendicular to the optical axis 3. The first hologram optical element 15 is arranged on the light exit side of the incident side polarizing plate 4 as an optical element tilted perpendicular to the optical axis 3. Therefore, parallel light of the polarized specific light component passing vertically through the incident side polarizer 4 enters the first hologram optical element 15. On the light exit side of the first hologram optical element 15, the second hologram optical element 16 is provided in parallel to the first hologram optical element 15. As shown in FIG. On the light exiting side of the second holographic optical element 16, the LC cell 7, the emission-side polarizing plate 8 and the projection lens 9 are arranged perpendicularly to the optical axis 3 in this order.

The first hologram optical element 15 diffracts light of an arbitrary wavelength at a diffraction angle. The diffraction angle of light diffracted by the first hologram optical element 15 depends on the wavelength. The diffraction angles of the first hologram optical element 15 are formed with a uniform pitch d (= 0.856 nm). The first hologram optical element 15 generates light of three wavelength components of R, G and B. Light of the three wavelength components of R, G and B enters the second hologram optical element 16 at their specific angle of incidence. Specifically, light of the R wavelength component (λ = 640 nm) is emitted from the first hologram optical element 15 at an angle of 48.4 °. Light of the G wavelength component (λ = 550 nm) is emitted from the first hologram optical element 15 at an angle of 40 degrees. Light of the B wavelength component (λ = 460 nm) is emitted from the first hologram optical element 15 at an angle of 32.5 degrees.

The second hologram optical element 16 diffracts light of any wavelength. The diffraction angle of light diffracted by the second hologram optical element 16 depends on the wavelength. The second hologram optical element 16 causes light incident at a particular angle of incidence to enter each pixel of the LC cell 7 for corresponding colors. The second holographic optical element 16 has unit holographic optical elements arranged in combination by unit pixels each consisting of a set of three color (R, G and B) pixels of the LC cell 7. Such unit hologram optical elements have diffraction angles formed in the same manner as in the first embodiment. In the second hologram optical element 16, the pitch d _A of the diffraction angle at point HA is 3.141 nm, the pitch d _B of the diffraction angle at point HB is 2.182 nm and the pitch d of the diffraction angle at point HC _C is 1.624 nm.

As is apparent from the above, according to this LC projector, the parallel light emitted from the lamp 1 and reflected by the reflector 2 is diffracted by the first hologram optical element 15 at a diffraction angle for each wavelength. do. That is, the exiting light of each wavelength component from the first hologram optical element 15 enters the second hologram optical element 16 at an optimal angle of incidence. Therefore, it is possible to improve the diffraction efficiency of light of each wavelength component by the second hologram optical element 16. That is, the second hologram optical element 16 can efficiently concentrate the light of each wavelength component to the associated pixel of the LC cell 7 for the relevant color. As a result, a clear and bright projected image is obtained.

Since light is incident perpendicularly to the first hologram optical element 15, if the incident light is an S-polarized light component, reflection in the first hologram optical element 15 can be minimized. When a particular polarized light component enters the first hologram optic 15 vertically, there is an elliptical less polarized light produced by reflection to the back side of the first hologram optic 15. Therefore, it is possible to use light incident on the first hologram optical element 15 effectively and without waste.

The lamp 1, the reflector 2 and the incident side polarizer 4 can also be arranged linearly, whereby this LC projector can be made smaller than the LC projector of the first embodiment.

Although the LC projector has the first and second hologram optics 5, 6 arranged side by side, the arrangement is not limited to this particular form and will take the form shown in FIG. 9 or FIG.

In the first variant shown in Fig. 9, the transparent plate 10 made of glass or the like is arranged on the light exit side of the incident side polarizing plate 4 perpendicular to the optical axis 3. The first hologram optical element 15 is provided on the light incident surface of this transparent plate 10, and the second hologram optical element 16 is installed on the light exiting surface of the first hologram optical element 15. do.

In the second variant shown in FIG. 10, the transparent plate 10 is arranged on the light exit side of the incident side polarizing plate 4 perpendicular to the optical axis 3. The first hologram optical element 15 is provided on the light exit surface of this transparent plate 10, and the second hologram optical element 16 is mounted on the light exit surface of the first hologram optical element 15. do.

The LC projector according to the first and second variants has the same functions and advantages as the LC projector of the second embodiment.

In the LC projector according to the second embodiment, the light strikes the LC cell 7 at an angle relative to the incident light in the LC projector of the first embodiment. Therefore, the projection lens 9 is preferably arranged to be moved from the position of the LC cell 7.

Third Embodiment

11 is a cross-sectional view for explaining the structure of the LCD projector according to the third embodiment of the present invention. In order to avoid undue description, similar or identical reference numerals are given to the components of the present embodiment that are identical to the relevant components of the first embodiment.

The incident side polarizing plate 4 is provided on the side which reflects the light of the reflector 2 which reflects the light from the lamp 1 in parallel to the optical axis 3 perpendicular to the optical axis 3. The prism 20 is arranged on the light exit side of the incident side polarizing plate 4 as an optical element. The prism 20 has a light-incident surface inclined to the optical axis 3 and a light-extracting surface formed perpendicular to the optical axis 3. The hologram optical element 21 is provided perpendicularly to the optical axis 3 on the light exit side of the prism 20. On the light exiting side of the holographic optical element 21, the LC cell 7, the emission-side polarizing plate 8, and the projection lens 9 are arranged in the order described perpendicular to the optical axis 3.

The prism 20 rotates parallel light of specific polarized light components passing through the incident side polarizer 4 at different angles depending on the wavelength. Prism 20 has a light-incident surface that is inclined at about 38.2 ° with respect to the light-exciting surface. Thus, the angle of incidence of light on the prism 20 is about 38.2 degrees. The prism 20 has a reflection index of 1.962. Light of the R wavelength component (λ = 640 nm) emerges from the prism at an angle of 41.7 °. Light of the G wavelength component (λ = 550 nm) is emitted at an angle of 40 degrees from the prism. Light of the B wavelength component (λ = 460 nm) is emitted at an angle of 39 ° from the prism.

The hologram optical element 21 diffracts light of an arbitrary wavelength. The diffraction angle of the light diffracted by the hologram optical element 21 depends on the wavelength. The hologram optical element 21 causes light incident at a particular angle of incidence to enter each pixel of the LC cell 7 for corresponding colors. This holographic optical element 21 has unit holographic optical elements. This hologram optical element 21 has unit holographic optical elements arranged in combination with unit pixels each composed of a set of three color (R, G and B) pixels of the LC cell 7. Such unit hologram optical elements have diffraction angles formed in the same manner as in the first embodiment. In the hologram optical element 16, the pitch d _A of the diffraction angle at point HA is 1.006 nm, the pitch d _B of the diffraction angle at point HB is 0.848 nm and the pitch d _C of the diffraction angle at point HC is 0.733 nm.

The hologram optics 21 are arranged at intervals of about 10 μm with respect to the light-exciting surface of the prism 20 and at intervals of about 1100 μm with respect to the light-incident surface of the LC cell 7.

The operation of this LC projector will be discussed below.

As shown in FIG. 11, the light from the lamp 1 in this LC projector is reflected by the reflector 2 so as to be parallel to the optical axis 3. This parallel light enters perpendicular to the incidence side polarizer 4 which selectively passes certain polarized light components. Light of the polarized specific light component selected by the incident side polarizer 4 enters the prism 20 at an angle of incidence of 38.2 °. As shown in FIGS. 12-14, the light of the R, G and B wavelength components incident on the prism 20 are diffracted by the prism 20 at different diffraction angles, each exiting at different exit angles. The light leaving the prism 20 enters the hologram optical element 21 at an optimal angle of incidence for each wavelength component. The light of each wavelength component incident on the hologram optic 21 is focused on the relevant pixel of the LC cell 7 for significant colors.

The above will be described in detail for each of the R, G and B wavelength components.

As shown in FIG. 12, the light of the G wavelength component incident on the prism 20 at an angle of incidence of 38.2 ° is diffracted and exits the exit angle of 40 ° from the prism 20.

Light leaving the prism 20 enters the hologram optical element 21 at an incident angle of 40 °. Light incident on the point HB of the hologram optics 21 leaves the hologram optics 21 substantially vertical and strikes the relevant pixel for G of the LC cell 7. Light incident on the point HA of the hologram optical element 21 leaves the hologram optical element 21 at a predetermined exit angle and strikes the relevant pixel for G of the LC cell 7. Light incident on the point HC of the hologram optical element 21 leaves the hologram optical element 21 substantially vertical, and strikes the relevant pixel for G of the LC cell 7.

As shown in FIG. 13, the light of the R wavelength component incident on the prism 20 at an incidence angle of 38.2 ° is diffracted and exits from the prism 20 at an exit angle of 41.7 °. The light leaving the prism 20 enters the hologram optical element 21 at an incident angle of 43 °. Light incident on the point HA of the hologram optical element 21 leaves the hologram optical element 21 at right angles in essence and strikes the relevant pixel for R of the LC cell 7. Light entering the point HB of the hologram optical element 21 leaves the hologram optical element 21 at a predetermined exit angle and strikes the relevant pixel for R of the LC cell 7. Light incident on the point HC of the hologram optical element 21 leaves the hologram optical element 21 at a predetermined exit angle and strikes the relevant pixel for R of the LC cell 7.

As shown in FIG. 14, the light of the B wavelength component incident on the prism 20 at an incidence angle of 38.2 ° is diffracted and exits the prism 20 at an exit angle of 39 °. Light leaving the prism 20 enters the hologram optical element 21 at an incidence angle of 39 °. Light incident on the point HC of the hologram optic 21 leaves the hologram optic 21 at substantially right angles and strikes the relevant pixel for B of the LC cell 7. Light incident on the point HB of the hologram optical element 21 leaves the hologram optical element 21 at a predetermined exit angle and strikes the relevant pixel for B of the LC cell 7. Light incident on the point HA of the hologram optical element 21 leaves the hologram optical element 21 at a predetermined exit angle and strikes the relevant pixel for B of the LC cell 7.

As described above, according to this LC projector, the parallel light emitted from the lamp 1 and reflected by the reflector 2 is diffracted by the first hologram optical element 5 at different diffraction angles for each wavelength. do. That is, the exiting light of each wavelength component from the prism 20 enters the hologram optical element 21 at the optimum angle of incidence. Therefore, it is possible to improve the diffraction efficiency of light of each wavelength component by the hologram optical element 21. That is, the hologram optical element 21 can efficiently concentrate the light of each wavelength component with respect to the associated color to the associated pixel of the LC cell. Thus a clear and bright projected image can be obtained.

Fourth Example

15 is a cross-sectional view illustrating the structure of the LCD projector according to the fourth embodiment of the present invention. In order to avoid undue description, similar or identical reference numerals are given to the components of the present embodiment that are identical to the relevant components of the third embodiment.

The incident side polarizing plate 4 is provided on the side which reflects the light of the reflector 2 which reflects the light from the lamp 1 in parallel to the optical axis 3 perpendicular to the optical axis 3. The prism lens 25 is arranged on the light exit side of the incident side polarizing plate 4 perpendicular to the optical axis 3 as an optical element. The hologram optical element 26 is provided perpendicularly to the optical axis 3 on the light exit side of the prism lens 25. On the light exiting side of the hologram optical element 26, the LC cell 7, the emission-side polarizing plate 8 and the projection lens 9 are arranged in the order described perpendicular to the optical axis 3.

The prism lens 25 diffracts parallel light of specific polarized light components passing through the incident side polarizing plate 4 at angles different according to the wavelength. The light-incident surface of the prism lens 25 is a sawtooth-shaped lens surface. The light exiting surface of the prism lens 25 is a plane perpendicular to the optical axis 3. The prism lens 25 has a microlens 25a corresponding to the unit pixels each composed of three colors R, G, and B of the LC cell 7. In this case each micro lens 25a has a light-incident lens surface that is inclined at about 38.2 ° with respect to the light-exciting surface. The reflection index of each microprism lens 25a is 1.926. Light of the R wavelength component (λ = 640 nm) emerges from the prism lens 25 at an angle of 41.7 °. Light of the G wavelength component (λ = 550 nm) is emitted from the prism lens 25 at an angle of 40 degrees. Light of the B wavelength component (λ = 460 nm) is emitted at an angle of 39 ° from the prism lens 25.

The hologram optical element 26 is the same as in the third embodiment and focuses the light of the R wavelength component, the light of the G wavelength component, and the light of the B component to the associated pixel.

As described above, according to this LC projector, parallel light emitted from the lamp 1 and reflected by the reflector 2 is diffracted by the prism lens 25 at different diffraction angles for each wavelength. That is, the exiting light of each wavelength component from the prism lens 25 enters the hologram optical element 26 at the optimum angle of incidence. Therefore, the hologram optical element 26 is used to improve the diffraction efficiency of the light of each wavelength component with the hologram optical element 26 and to effectively concentrate the pixel of the LC cell 7 for the corresponding colors. It is possible to diffract effectively. This can provide a clear and bright projected image.

In the fourth embodiment, the microprism lenses 25a constituting the prism lens 25 are combined into unit pixels each consisting of three color (R, G and B) pixels of the LC cell 7.

[Fifth Embodiment]

16 is a cross-sectional view illustrating the structure of the LCD projector according to the fifth embodiment of the present invention.

In order to avoid undue description, similar or identical reference numerals are given to the components of the present embodiment that are identical to the relevant components of the first embodiment.

In this LC projector, the lamp 1 is located in focus of the reflector 2 with an elliptical surface. The reflector 2 reflects the light generated from the lamp 1 to produce light parallel to the optical axis 3. The hologram optical element 51 is arranged on the light reflecting surface of the reflector 2 and tilts with respect to the optical axis 3. On the light exiting side of the holographic optical element 51, the incident side polarizing plate 4 for selectively passing the specific polarized light component is arranged parallel to the holographic optical element 51. As shown in FIG. A flat-shaped condenser lens 50 is arranged in parallel with the incident side polarizer 4 on the light exit side of the polarizer 4. The LC cell 7 is provided on the light exit side of the condenser lens 50 in parallel with the condenser lens 50. An emission-side polarizing plate 8 for selectively passing a specific polarized light component among the light passing through the LC cell 7 is arranged on the light exit side of the LC cell 7 in parallel with the LC cell 7. The projection lens 9 for projecting the image of the light passing through the exit side polarizing plate 8 is provided on the light exit side of the light exit side polarizing plate 8.

The LC cell 7 has liquid crystals sealed between a pair of transparent substrates on which electrodes are formed in a dot matrix form and a plurality of pixels are arranged in a dot matrix form. The black matrix BM for preventing light leakage is provided between the pixels on the substrate where light is incident. As shown in FIG. 18, the LC cell 7 has unit pixels arranged in an annular shape, each of which consists of a set of three color (R.G and B) pixels. Each pixel of R, G and B is arranged along the direction in which the light of the hologram optical element 51 to be discussed later from left to right in the order of B, G and R is split. This LC cell 7 is equipped with color filters for R, G and B. However, the LC cell 7 may not be equipped with color filters. The hologram optical element 51 diffracts light of an arbitrary wavelength into each diffraction grating. The diffraction angle of the light diffracted by the hologram optical element 51 varies depending on the wavelength. As shown in FIG. 17, parallel light emitted from the lamp 1 and reflected by the reflector 2 enters the hologram optical element 51 at a predetermined incident angle. The hologram optical element 51 splits incident light into parallel light for each wavelength band. In other words, the diffraction gratings of the hologram optical element 51 are formed at a uniform pitch. The hologram optical element 51 substantially diffracts the light of the G wavelength band toward the direction of the normal and thus causes the light to leave. The hologram optical element 51 diffracts the light of the B wavelength band at a smaller diffraction angle than the light of the G wavelength and thus allows the light to be taken out.

In Fig. 18, the direction (final direction) of splitting the light of the hologram optical element 51 is determined from the left to the right direction.

Regarding the relevant colors, the condenser lens 50 focuses the parallel light of the respective wavelengths split by the hologram optical element 51 to the relevant pixel of the LC cell 7. The condenser lens 50 has microlenses 50a arranged annularly in combination with unit pixels each composed of three colors R, G and B pixels of the LC cell 7. As shown in FIG. 18, each microlens 50a is formed in a hexagonal shape having a pixel for G of the LC cell 7 in the center and connecting the centers of six adjacent pixels for R and B around the center pixel. . As shown in FIG. 17, the microlens 50a is a convex lens having a convex surface toward the hologram optical element 51. The microlens 50a focuses the parallel incident light of each wavelength band to the relevant pixel of the LC cell 7 for that color according to the wavelength (incidence angle) of the light. Specifically, the light of the G wavelength band is focused on the relevant pixel for G of the LC cell 7, the light of the R wavelength band is focused on the related pixel for R of the LC cell 7 and the light of the B wavelength band. Is concentrated in the relevant pixel for B in the LC cell 7.

The operation of this LC projector will now be discussed.

As shown in FIG. 16, the light from the lamp 1 is reflected by the reflector 2 such that it is parallel to the axis 3. This parallel light enters the hologram optical element 51 at a predetermined incident angle. As shown in FIG. 17, parallel light incident on the holographic optical element 51 is diffracted by the holographic optical element 51 at different diffraction angles for the R, G, and B wavelength bands, and the diffracted light is each wavelength band. Leave hologram optics 51 as parallel lights for. In detail, the light of the G wavelength band is substantially diffracted in the normal reflection of the holographic optical element 51, thus leaving the holographic optical element 51. The light of the R wavelength band is diffracted at a diffraction angle larger than that of the G wavelength band, and leaves the hologram optical element 51 at a predetermined angle in the normal direction of the hologram optical element 51. The light of the B wavelength band is diffracted at a diffraction angle smaller than that of the G wavelength band, and the hologram optical element 51 is moved at a predetermined angle opposite to the exit direction of the light of the R wavelength with respect to the normal of the hologram optical element 51. I'm leaving.

The exiting light from the hologram optical element 51 enters the incident side polarizer 4 which selectively passes certain polarized light components. Light passing through the incident side polarizer 4 enters each microlens 50a of the condenser lens 50 at different incident angles for each wavelength. As shown in FIG. 17, light incident on the microlens 50a at different incidence angles is collected by the microlens 50a in the relevant pixel of the LC cell 7 for the corresponding colors. In detail, the light of the G wavelength band substantially perpendicular to the associated microlens 50a is concentrated in the relevant pixel for G of the LC cell 7. Light of the R wavelength band entering the associated microlenses 50a at a predetermined angle is focused on the relevant pixel for R of the LC cell 7. Light of the B wavelength band entering the related microlenses 50a at a predetermined angle is focused on the relevant pixel for B of the LC cell 7.

The polarized light components of the light passing through the LC cell 7 are selectively passed by the exit side polarizer 8. The light passing through this exit side polarizing plate 8 is projected as an image by the projection lens 9.

As described above, in accordance with the LC projector, the parallel light emitted from the lamp 1 and reflected by the reflector 2 is different diffraction angles for the R, G and B wavelength bands by the hologram optic 51. Is diffracted. Parallel lights with different angles of incidence with respect to R, G and B leave the hologram optical element 51. It is therefore possible to split the light from the lamp 1 into light components of wavelength bands with less portions. This aspect simplifies the structure of the LC projector.

In addition, the microlenses 50a of the condenser lens 50 focus each light split by the hologram optical element 51 into an associated pixel of the LC cell 7 matching the wavelength bands. This prevents the light of the complementary color components from being absorbed by the color filter or prevents the light from the lamp 1 from being obscured by the black matrix BM. Therefore, this LC projector can prevent light loss. Thus, the utilization efficiency of the light emitted from the lamp 1 can be improved to obtain a bright color image and a bright projected image.

[transform]

The hologram optics 5, 15 and 51 used in the first, second and fifth embodiments diffract light of any wavelength band into each diffraction grating such that the light is diffracted into diffraction gratings different for each wavelength. Let's do it. That is, even though each of the hologram optical elements used in the first, second and fifth embodiments has a single element structure, the structure of such hologram optical elements is not limited to this form. For example, three types of three-layer structure types of holographic optics capable of selectively passing lights of respective R, G and B wavelengths may be used.

Holographic optics in the first, second and fifth embodiments and prisms in the second and fourth embodiments are used as means for splitting parallel light from the lamp. On the other hand, according to the present invention, all the optical means for splitting the incident light by wavelength and emitting the split light components according to the wavelength may be used in place of holographic optics and prisms.

In the first to fourth embodiments the incidence side polarizer is arranged on the light incidence side of the optical means (hologram optics 5, 15 and prisms 20, 25, while in the fifth embodiment the incidence side polarizer It is arranged on the light exiting side of the optical means The incident side polarizer may however be used on both sides.

The holographic optical elements in the first to fourth embodiments and the microlenses in the fifth embodiment focus light incident at different angles for the respective wavelength bands to a predetermined and associated pixel. On the other hand, according to the present invention, all the optical means for focusing light incident at different angles for each wavelength band into certain and related pixels may be used in place of the mentioned holographic optical elements and microlenses.

Although each microlens has a hexagonal shape in the fifth embodiment, the structure of the microlens is not limited to this form. For example, as shown in FIG. 19, each of the unit pixels will have three pixels for R, G, and B arranged in a linear manner, and each microlens 50b is formed in a polygonal shape combined with this unit pixel. May be The condenser lens is formed by arranging such microlenses 50b in an annular shape.

Although the foregoing description of the embodiments of the first to fifth examples is given when the present invention is applied to an LC project, the present invention is not limited to this particular application. The present invention may be applied to various LCD devices that allow the viewer to directly observe the image displayed on the LC cell 7.

LCD devices according to the first to fifth embodiments will be regarded as some applicable form of the present invention. The present invention is applicable to all LCD devices using two optical means combined. The method for combining such two optical means and the features of those two optical means may be selected to provide the required result through experiments.

Claims (13)

Light sources 1 and 2 for providing essentially luminous flux; A liquid crystal device 7 having multiple pixels; First hologram optical elements (5, 15) for splitting the essentially parallel luminous flux from the light sources (1,2) into luminous fluxes of different wavelength bands and for emitting the split luminous flux in different directions; And second hologram optical elements 6 and 16 for guiding the luminous fluxes of the plurality of different wavelength bands emitted from the first holographic optical elements 5 and 15 to predetermined pixels of the liquid crystal device 7 for each wavelength band. It includes; The first hologram optical elements 5 and 15 split essentially parallel light beams from the light sources 1 and 2 into parallel light beams in a plurality of different wavelength bands, and emit the split parallel light beams in different directions. Liquid crystal display device characterized in that. 2. The method of claim 1, wherein each of the incidence angles of the luminous fluxes incident on the second holographic optical element (6, 16) is determined by the second holographic optical element for each of the wavelength bands of the luminous fluxes. 6, 16) the liquid crystal display, characterized in that falling within a predetermined range including the angle of incidence to maximize the diffraction efficiency. The liquid crystal display device according to claim 1, wherein the light from the light sources (1, 2) hits the first hologram optical element at an angle. 4. The light source according to claim 3, further comprising a flat plate (4) disposed between the light sources (1, 2) and the liquid crystal device (7), wherein one luminous flux from the light sources (1, 2) is Liquid crystal display device characterized in that it enters perpendicular to the polarizing plate (4). The liquid crystal display device according to claim 1, wherein the first holographic optical elements (5, 15) and the second holographic optical elements (6, 16) are respectively mounted on both sides of the transparent plate (10). . The liquid crystal display according to claim 1, wherein the first holographic optical elements (5, 15) and the second holographic optical elements (6, 16) are respectively mounted on one side of the transparent plate (10). . The liquid crystal according to claim 1, wherein when light from the light sources (1, 2) is diffracted by the first hologram optical elements (5, 15), the diffraction angle becomes larger as the wavelength of the light becomes longer. Display. Light sources 1 and 2 for providing essentially luminous flux; A liquid crystal device 7 having multiple pixels; Prisms (20, 25) for splitting the essentially parallel luminous flux from the light sources (1,2) into luminous fluxes in a plurality of different wavelength bands and for emitting the split luminous fluxes in different directions; And second hologram optical elements 21 and 26 for guiding the light fluxes of the plurality of wavelength bands emitted from the prisms 20 and 25 to predetermined pixels of the liquid crystal device 7 for each wavelength band. LCD display device. 9. The prism (20, 25) according to claim 8, wherein the prisms (20, 25) split essentially parallel light fluxes from the light sources (1,2) into balanced light fluxes in a plurality of different wavelength bands, and the split parallel light fluxes in different directions. Liquid crystal display characterized in that the emission. The liquid crystal display device according to claim 8, wherein the prism (25) is an aggregate of a plurality of microprisms (25a). 9. The prism (20, 25) according to claim 8, wherein the prisms (20, 25) split essentially essentially parallel luminous flux from the light sources (1,2) into essentially parallel luminous fluxes in a plurality of different wavelength bands, respectively. A liquid crystal display device, characterized in that to emit in different directions. 9. The holographic optics of claim 8, wherein each of the incidence angles of the luminous fluxes incident on the holographic optical element (21, 26) from the prisms (20, 25) is each of the wavelength bands of the luminous fluxes. A liquid crystal display device characterized by falling within a predetermined range including an angle of incidence for maximizing diffraction efficiency of the elements (21, 26). Light sources 1 and 2 for providing essentially luminous flux; A liquid crystal device 7 having multiple pixels; First optical means 5, 15 for splitting the essentially parallel luminous flux from the light sources 1, 2 into luminous fluxes of different wavelength bands and for emitting the split light fluxes in different directions 20, 25, 51); Second optical means 6 for guiding the light fluxes of the plurality of different wavelength bands emitted from the first optical means 5, 15, 20, 25, 51 to a predetermined pixel of the liquid crystal device 7 for each wavelength band; , 16, 21, 26, 50); The first optical means (5, 15, 20, 25, 51) split essentially parallel light flux from the light sources (1, 2) into parallel light fluxes of a plurality of different wavelength bands, each of the split parallel light fluxes. A liquid crystal display device, characterized in that to emit in different directions.

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