JPH07104232A - Linear polarization device and liquid crystal display device - Google Patents

Abstract

(57) [Summary] [Structure] The selective reflection liquid crystal element 1 of the cholesteric liquid crystal cell selectively reflects light of a specific wavelength to separate it into left-handed circularly polarized light and right-handed circularly polarized light, and arranges them on the optical path of each. 1
After they are converted into linearly polarized light by the / 4 wavelength retardation plates 2 and 4, respectively, linearly polarized light combined by the other selective reflection liquid crystal element 6 is obtained. A liquid crystal display device is obtained by combining this configuration with a polarization control type liquid crystal cell such as a TN type. [Effect] In principle, non-polarized incident light can be converted into linearly polarized light without loss, and a polarizing device with high conversion efficiency and therefore bright can be obtained. Further, the manufacturing cost is low, and a light and compact device can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear polarization device and a liquid crystal display device using the same, and more particularly to a liquid crystal display device suitable for projection type display.

[0002]

2. Description of the Related Art Generally, a liquid crystal cell used in a liquid crystal display device is a polarization control type liquid crystal cell (eg, TN type LCD, STN type LCD, ECB type LCD, F type) which uses two polarizing plates.
(LC type LCD etc.) and a scattering type or dye addition type liquid crystal cell (for example, polymer dispersion type LCD, PC type LCD, GH type LCD etc.) which does not use a polarizing plate or uses one sheet.

Since a polarization control type liquid crystal cell and a scattering type or dye addition type liquid crystal cell using one polarizing plate use a polarizing plate for polarizing input or output light, its maximum transmittance is at least 50% or less. Will end up. This is because the polarization control type liquid crystal cell requires linearly polarized light as light to be incident as its display principle, and therefore one polarizing plate is used as a polarizer, and whether light is emitted or not is controlled. One polarizing plate is used as an analyzer for this purpose, and the dye-added type liquid crystal cell is provided with a dye to function as one or both of the polarizer and the analyzer. In any case, the polarizer absorbs the orthogonal light components in order to convert the unpolarized light into the linearly polarized light. Therefore, the maximum transmittance of the liquid crystal display device is at least 50% or less. Therefore, these liquid crystal display devices have a dark display,
In particular, when it is applied to a projection type TV or the like, the light source must be strengthened, and even if the light source is strengthened, the absorption and dispersion of light from the light source by the polarizing plate is burdened, which is a problem.

On the other hand, a scattering type liquid crystal cell (for example, a polymer-dispersed LCD) which does not use a polarizing plate does not use a polarizing plate, and therefore its maximum transmittance can be set to about 80% (20%). The absorption of light is due to the light absorption of a member such as a substrate.) In recent years, its application to a projection TV has been actively studied. However, this scattering type liquid crystal cell
In addition to its optical characteristics having temperature dependence, it also has a short life and has not been put to practical use.

Against this background, in projection type TVs and the like, a technique for making unpolarized light linearly polarized without absorbing half of the light by using a beam splitter, a prism and a phase difference plate has been actively studied in recent years. ing.

Method using the former beam splitter
(M.Imai et.al., JAPAN DISPLAY '92, P235), in principle, a high degree of polarization is obtained, and the transmittance is also bright,
This optical system is large and heavy, is difficult to manufacture, is expensive, and is not practical.

The latter method using a prism and a retardation plate
(S.Sakai et.al., SID'91, p301) has a high transmittance, but is not practical because the degree of polarization is poor due to the wavelength dependence of the retardation plate.

Also, M. Schadt et al. Have proposed a method for obtaining a polarizer in SID'90, p324 by utilizing the selective reflection of cholesteric liquid crystal as in the case of the above two methods. Since the light is decomposed into light and is incident on the cell, the light utilization rate is about 100%, but the light incident on the cell is 50% or less, which is not so bright and not practical.

[0009]

As described above, since a typical polarization control type liquid crystal device uses a polarizing plate as a polarizer, there is a problem that the light loss is large and the display is dark. Further, a scattering type device that does not use a polarizer has not been put to practical use in terms of operation and life. Therefore, it has been proposed to combine a polarization control type liquid crystal device with a device using a beam splitter or a prism as a polarization device for converting unpolarized light into linearly polarized light, but such a polarization device is complicated. In addition, there is a problem that the weight becomes large and the polarization characteristic is not sufficient.

It is an object of the present invention to obtain a linear polarization device that converts unpolarized light into linearly polarized light, in which the above-mentioned disadvantages are improved.

Further, a liquid crystal display device using the improved linear polarization device is obtained.

[0012]

In the present invention, as a means for solving the above-mentioned problems, one direction in which the incident light of a specific wavelength is selectively reflected in the direction of the first optical path and travels in the first optical path. First selective reflection that separates circularly polarized first circularly polarized light and second incident circularly polarized light that selectively transmits the incident light in a second direction and travels in a second optical path A liquid crystal element, a first quarter-wave retardation plate located on the first optical path for converting the first circularly polarized light into first linearly polarized light, and a second optical path on the second optical path. A second quarter-wave retarder for locating and converting the second circularly polarized light into second linearly polarized light, and transmitting the first linearly polarized light from the first optical path, Second
Of the second selective reflection liquid crystal element for obtaining the third linearly polarized light by reflecting the second linearly polarized light from the optical path of (1) and synthesizing the linearly polarized light.

Further, the above-mentioned linear polarization device is obtained in which the incident light is light having a peak wavelength in any of red, green and blue.

Further, the first circularly polarized light that selectively reflects the incident light and travels in the first optical path and the second circularly polarized light that selectively transmits and travels in the second optical path are separated. A selective reflection liquid crystal element, a first quarter-wave retarder that is located on the first optical path and converts the first circularly polarized light into first linearly polarized light, and the second light A second quarter-wave retarder that is located on the road and converts the second circularly polarized light into second linearly polarized light, and transmits the first linearly polarized light from the first optical path. A linear polarization device comprising a second selective reflection liquid crystal element for reflecting the second linearly polarized light from the second optical path and synthesizing the linearly polarized light to obtain a third linearly polarized light; Three
(2) A liquid crystal display device comprising a polarization control liquid crystal device which receives linearly polarized light and controls the polarized light to be emitted light, and a polarizing device which is arranged on the optical path of the emitted light and operates as an analyzer.

Further, three combinations of an incident light polarization device and a polarization control liquid crystal device corresponding to the red wavelength light, the green wavelength light and the blue wavelength light respectively are provided, and the emitted lights emitted from these sets are combined. The liquid crystal display device is characterized in that the liquid crystal display device is characterized in that it passes through an outgoing light polarization device that operates as an analyzer.

Further, the above liquid crystal display device is obtained in which the polarization control liquid crystal device is a TN type liquid crystal device.

Further, in a liquid crystal display device having at least one polarization control type liquid crystal display cell and a linear polarization device for making linear polarization light incident on the polarization control type liquid crystal display cell, the linear polarization device is made incident. Peak wavelength of light λm
A cholesteric liquid crystal cell or a polymer liquid crystal film that selectively reflects and obtains circularly polarized reflected light and transmitted light,
Light of a peak wavelength λm is made incident, and [{(1 + 2k) /
4} λm] (k = 0,1,2, ...) and acts as a retardation to transmit the reflected light and the transmitted light of the circularly polarized light, respectively, and make each of the transmitted light a linearly polarized light.
A wavelength phase difference plate and a cholesteric liquid crystal cell that selectively reflects one of these linearly polarized lights and transmits one of the linearly polarized lights to combine the respective linearly polarized lights into linearly polarized lights having the same polarization axis and selectively reflects the peak wavelength λm. Alternatively, the present invention provides a liquid crystal display device comprising a polymer liquid crystal film and allowing the synthesized linearly polarized light to enter the polarization control type liquid crystal display cell.

[0018]

The operation of the present invention will be described below with reference to FIG.

FIG. 2 shows a linear polarization device according to one embodiment of the present invention, which comprises a first selective reflection liquid crystal element 1, a second selective reflection liquid crystal element 6, a first quarter-wave retarder 2 and a second selective reflection liquid crystal element 2. 1/4 wavelength retardation plate 4, and additionally includes a first mirror 3 and a second mirror 5.

After the light emitted from the white visible light source through the filter or the dichroic mirror is separated into monochromatic light having a bandwidth having a width of about 80 nm to some extent,
It is converted into linearly polarized light by light control by the linearly polarizing device shown in the figure.

In the figure, a wavelength λm, for example, λ1 indicating a red color
The first selective reflection liquid crystal element 1, for example, a cholesteric liquid crystal film whose twist pitch is controlled so as to selectively reflect at an incident angle of light, for example, at 45 °, is irradiated with non-polarized light having a peak wavelength. When the spiral direction of the cholesteric liquid crystal film used here is left-handed, the light LCL that is selectively reflected becomes left-handed circularly polarized light and travels along the first optical path LA. On the contrary, the right-hand circularly polarized light LCR is transmitted and travels along the second optical path LB. If the value obtained by multiplying the birefringence of the liquid crystal material used for the cholesteric liquid crystal film by the twist pitch is set to be equal to or more than the bandwidth (about 80 nm) of the light emitted from the light source, all the unpolarized light L incident at this wavelength can be obtained. It can be selectively reflected and transmitted. Therefore, the respective circularly polarized light has a brightness of 50% of the incident light L.

Next, the wavelength of the incident light for each of these circularly polarized light LCL, LCR (a bandwidth equal to or less than the value obtained by multiplying the birefringence of the liquid crystal material used for the cholesteric liquid crystal film with the peak wavelength λ1 as the center and the twist pitch) Light) is made incident on a retardation plate (referred to as a quarter-wave retardation plate in the present invention) having a function of shifting the phase of 1/4 + k / 2 (k = 0, 1, 2, ...). The retardation value Rd and the wavelength dependence of the quarter-wave retarder are the birefringence and the twist pitch of the liquid crystal material used in the first selective reflection liquid crystal element around the wavelength of the light (λ1). 1/4 + k / 2 (k = 0, consisting of a bandwidth equal to or smaller than the multiplied value)
1, 2, ...) are used. That is, by arranging the first and second quarter-wave retarders 2 and 4 on the optical paths LA and LB, respectively, the circularly polarized lights LCL and LCR incident on these retarders are both perfect. It is converted into linearly polarized light LDL and LDR.

After that, using the mirrors-3 and 5, the traveling directions of the two linearly polarized lights LDL and LDR (first and second optical paths L
(A, LB) are made orthogonal to each other, and, similarly to the selective reflection liquid crystal layer 1, a value obtained by multiplying the birefringence and the twist pitch of the liquid crystal material used for the cholesteric liquid crystal film around the wavelength of incident light (λ1 as a center). The second selective reflection liquid crystal element 6 composed of a cholesteric liquid crystal cell for selectively reflecting (the following bandwidth) is irradiated. Here, conditions are set so that selective reflection occurs at an incident angle of 45 °, and the two linearly polarized lights LDL and LDR are arranged so as to be irradiated at an angle of 45 °. By doing so, one linearly polarized light LDL goes straight and is transmitted, and the other linearly polarized light LDR is bent and reflected at a right angle, so that the two linearly polarized lights have the same polarization axis, the same polarization direction, and the same traveling direction. It becomes a linearly polarized light LD. In principle, the light control system described above does not absorb light (however, there is some absorption by each member). Also,
Since the finally emitted light LD is a combined light of two lights having a brightness of 50% of the incident light, the brightness of the emitted light is almost 100% of the incident light.

By providing such an optical system according to the present invention for each of the three primary colors of light, red R, green G, and blue B, light having a wavelength required for approximately full-color display can be obtained.
It is possible to control the display by making the light incident on one polarization control type liquid crystal cell.

For example, when a TN type liquid crystal cell is used as a polarization control type liquid crystal cell, the light incident on each cell is linearly polarized light, and the light transmitted through the TN type liquid crystal cell is a common analyzer which is a polarizing device. It can be made incident. TN
When the linearly polarized light passing through the cell passes through the transmission axis of the polarizing plate, there is no light absorption in principle, and the final transmittance is almost 100%. However, as described above, there is a slight amount of absorption in each member, so that it is substantially more than 80%.

[0026]

Embodiment An embodiment of the present invention will be described in detail below with reference to FIG.

Example 1 FIG. 1 shows a projection type liquid crystal display device. A halogen lamp is used as the light source 10, and RGB
Dichroic mirror that reflects monochromatic light of 11R, 1
Place 1G and 11B continuously. Here, the wavelength of the light reflected by each dichroic mirror is 586 nm to 6 when the mirror 11 R has a peak wavelength of λ1 = 620 nm.
74 nm bandwidth λ R, mirror 11G has λ2 = 550 n
It has a bandwidth λ G of 490 nm to 570 nm with m as a peak wavelength, and a bandwidth λ B of 400 nm to 480 nm with the mirror 11B having a peak wavelength of λ3 = 440 nm.

The light reflected by each dichroic mirror is shown in the following respective linear polarization devices 12R, 12G,
It is incident on 12B.

Each linear polarization device has the same optical system configuration as shown in FIG. 2, and has different characteristics depending on the wavelength to be handled. This linear polarization device will be described with reference to FIG.

First selective reflection liquid crystal element 1 for red light R
Uses polyimide (trade name AL-3046, made by Japan Synthetic Rubber) as an alignment film on two glass substrates, and uses rubbing alignment treatment (the rubbing direction is the same in the upper and lower substrates).
Then, the liquid crystal layer is made into a cell with a thickness of 10 μm,
24 wt% of a left-handed chiral agent (trade name S-811, made by Merck Japan) in a nematic liquid crystal (product name E-7, made by Merck Japan) having a refractive index anisotropy Δn = 0.23.
It is obtained by mixing and filling a liquid crystal having a spiral pitch of 0.387 μm between substrates and sandwiching it as a liquid crystal layer. As a liquid crystal cell to be obtained, the selective reflection liquid crystal element 1 selectively reflects a left circularly polarized light component having a bandwidth λR having a wavelength of 586 nm to 674 nm and transmits a right circularly polarized light component out of light incident at 45 ° through the dichroic mirror 11R. It has a function to let.

First selective reflection liquid crystal element 1 for green light G
Uses polyimide (trade name AL-3046, made by Japan Synthetic Rubber) as an alignment film on two glass substrates, and uses rubbing alignment treatment (the rubbing direction is the same in the upper and lower substrates).
Then, the liquid crystal layer is made into a cell with a thickness of 10 μm,
27 wt% of a left-handed chiral agent (trade name S-811, manufactured by Merck Japan) in a nematic liquid crystal (product name E-7, manufactured by Merck Japan) having a refractive index anisotropy Δn = 0.23.
It is obtained by mixing and filling a liquid crystal having a helical pitch of 0.343 μm between substrates and sandwiching it as a liquid crystal layer. The obtained liquid crystal cell has a function of selectively reflecting the left circularly polarized light component having a bandwidth λG having a wavelength of 485 nm to 574 nm and transmitting the right circularly polarized light component of the light incident at 45 ° from the dichroic mirror 11G.

In the first and second selective reflection liquid crystal elements for blue light B, polyimide (trade name AL-3046, made by Japan Synthetic Rubber) is used as an alignment film on two glass substrates, and this is subjected to rubbing alignment treatment. (The rubbing direction is the same for the upper and lower substrates), and a nematic liquid crystal having a refractive index anisotropy Δn of 0.23 (trade name E-7, manufactured by Merck Japan) is formed into a cell with a liquid crystal layer thickness of 10 μm. To the left twisted chiral agent (trade name S-811, made by Merck Japan) 34w
It was obtained by mixing t% and filling a liquid crystal having a helical pitch of 0.275 μm between substrates and sandwiching it as a liquid crystal layer.
The resulting liquid crystal cell is 4 from the dichroic mirror 11B.
Of the light incident at 5 °, the wavelength is 399 nm to 488n
It has the function of selectively reflecting the left-handed circularly polarized light component with a bandwidth λ B of m and transmitting the right-handed circularly polarized light component.

Next, as the quarter-wave retarders 2 and 4 for converting each circularly polarized light into linearly polarized light, a retardation plate made of polycarbonate is used as the first and second optical paths A of each linear polarization device. , B. 1 / of each linear polarization device
The retardation of the 4-wavelength phase difference plate is as follows.

The retardation of the quarter-wave retarder for the red light R is such that the retardation RdR for each wavelength is about 0.25 times that of the light λR having a wavelength of 586 nm to 674 nm. The retardation of the quarter-wave retarder for the green light G is λG having a wavelength of 490 nm to 570 nm.
On the other hand, the retardation RdG for each wavelength has a wavelength-dependent characteristic that is approximately 0.25 times each wavelength, and the retardation of the quarter-wave retarder for the blue light B. Is light λ having a wavelength of 400 nm to 480 nm.
In contrast to B, the retardation RdB for each wavelength has a wavelength-dependent characteristic that is approximately 0.25 times each wavelength.

Next, the light is incident on the second selective reflection liquid crystal element 6 for combining these linearly polarized lights at an incident angle of 45 °.

The second selective reflection liquid crystal element 6 of each linear polarization device has the same structure as the first selective reflection liquid crystal element 1 except for the chiral agent.

That is, the second selective reflection liquid crystal element of the linearly polarizing device 12R for red light uses polyimide (trade name AL-3046, made by Japan Synthetic Rubber) as an alignment film on two glass substrates and rubs it. Alignment treatment (the rubbing direction is the same in the upper and lower substrates) was performed to form a liquid crystal layer having a thickness of 10 μm, and the liquid crystal layer was made into a cell.
24% by weight of a right-handed chiral agent (trade name R-811, made by Merck Japan) was mixed with nematic liquid crystal (trade name: E-7, made by Merck Japan) of, and the spiral pitch of the liquid crystal was 0.387 μm. It is obtained by filling between the substrates and sandwiching them as a liquid crystal layer. The resulting liquid crystal cell has a second optical path B
Of light incident at 45 ° from 586 nm to 6 nm
It has a function of selectively reflecting the right circularly polarized light component having a bandwidth λ R of 74 nm and transmitting the left circularly polarized light component.

Similarly, the second selective reflection liquid crystal element for the green light G and the second selective reflection liquid crystal element for the blue light B are twisted to the right instead of the chiral agent of the first selective reflection liquid crystal element. It is constituted by adding a chiral agent (R-811).

As a result, the second selective reflection liquid crystal element for the green light G (the liquid crystal has a spiral pitch of 0.343 μm) has 45 pixels.
Of the light incident at ゜, the wavelength is 485nm-574nm
It has the function of selectively reflecting the right circularly polarized light component of the light λ G and transmitting the left circularly polarized light component.

Further, in the second selective reflection liquid crystal element for blue light B (the helical pitch of the liquid crystal is 0.275 μm), the light λ having a wavelength of 399 nm to 488 nm out of the light incident at 45 °.
It has the function of selectively reflecting the right circularly polarized light component of B and transmitting the left circularly polarized light component.

The second selective reflection liquid crystal element is arranged at a position where the first and second optical paths LA and LB of each linear polarization device are orthogonal to each other, and combines the linearly polarized light incident on this. The linearly polarized light that has entered the first optical path and is incident on the second
The linearly polarized light that has passed through the selective reflection liquid crystal element of No. 2 and travels along the second optical path and is incident is reflected by the second selective reflection liquid crystal element without being transmitted. These lights are combined and emitted as linearly polarized light. In this way, each linear polarization device 12R
, 12G and 12B, linearly polarized lights LR, LG and LB of red R, green G and blue B were obtained.

The degree of polarization and the transmittance of each linearly polarized light were measured using a polarizing plate. The brightness when the transmission axis of the polarizing plate is parallel to the polarization axis of the linearly polarized light is the RG reflected by the dichroic mirrors 11R, 11G, and 11B.
R is 97.0% and G is 9 with respect to the brightness of the light of B.
It was 6.5% and B was 96.0%. In addition, the brightness when the transmission axis of the polarizing plate is orthogonal to the polarization axis of the linearly polarized light is the R, G, and B reflected by the dichroic mirror.
R is 0.65% and G is 0.5
2% and B was 0.41%. Therefore, the respective transmittances and degrees of polarization are as follows.

The transmittance of R is 97.0% and the degree of polarization is 99.34%.

The transmittance of G is 96.5% and the polarization degree is 99.50%.

The transmittance of B is 96.0% and the polarization degree is 99.61%.

The linearly polarized light LR, LG, obtained as described above,
LB is a polarization control type liquid crystal device T as shown in FIG.
TN type LCD 13R with FT switching element, 1
It was made incident on 3G and 13B. The TN LCDs are all manufactured under the same conditions and the number of pixels is 640 × 480. The retardation (Δnd) is 0.475 μm.
Is set to. As shown in FIG. 1, dichroic mirrors 14R, 14G, and 14B are arranged so that the light emitted from these TN type LCDs can be combined, and an outgoing light polarization device 15 that operates as an analyzer is arranged at the end of the optical path. The display mode of each TN type LCD 13R, 13G, 13B is set so as to be normally white mode, and the lens 1
Use 6 to project. When the brightness of this projected light was measured, when each TN LCD was turned off (light transmission) over the entire surface, a very bright display with 65% of the brightness of the light source was obtained, indicating that it was on (light cut off). When this was done, a very dark display of 0.31% of the brightness of the light source was obtained. The estimated contrast ratio was 212: 1.

(Embodiment 2) T for display in Embodiment 1
A liquid crystal display device of the present invention was prepared under the same conditions, materials, and manufacturing methods as in Example 1 except that the N-type LCD was a VAN-type LCD.
When the brightness of the projected light was measured, when each VAN LCD was turned off, 57% of the brightness of the light source was obtained, and a very bright display was obtained as in the first embodiment. 0.26% of the brightness of the light source and the same as Example 1.
A very dark display was obtained. The estimated contrast ratio was 219: 1.

(Third Embodiment) T for display in the first embodiment
Conditions and materials similar to those of Example 1 except that the N-type LCD is a STN type LCD in a monochrome mode using a quarter-wave retarder.
When a projection type liquid crystal display device was created by the manufacturing method and the brightness of the projected light was measured by multiplex drive, each ST
When the entire N-type LCD is turned off, the brightness of the light source is 58%, and a very bright display is obtained as in the first embodiment. When the entire-on is turned on, the brightness of the light source is 0.78%. As in Example 1, a very dark display was obtained. The estimated contrast ratio was 73: 1.

(Embodiment 4) In this embodiment, the mirror 5 arranged on the second optical path LB shown in FIG. 2 is a dichroic mirror which selectively reflects red light and transmits light of other wavelengths. This is a device having the same characteristics as the red light linearly polarizing device 12R of the first embodiment.

Assuming that the incident light L is unpolarized white light, the left circularly polarized red light λ R is reflected and proceeds in the first optical path LA,
The right circularly polarized red light λ R and other wavelength light are transmitted and proceed on the second optical path LB. When these transmitted lights are incident on the dichroic mirror 5 arranged on the second optical path, only the right circularly polarized red light λR is reflected and the other wavelength lights are transmitted or absorbed. Therefore, the linearly polarizing device 12 for red light according to the first embodiment is used.
Similar to R, it is possible to obtain linearly polarized light in which red light is combined. Further, as a modification, if the mirror is a total reflection mirror and a red light filter is arranged before or after the optical path of the mirror, the same effect can be obtained.

In the above embodiment, the specific material and manufacturing method have been described, but it is needless to say that the same effect can be obtained by using other materials and manufacturing methods as long as the effects of the present invention can be obtained. As the selective reflection liquid crystal element, a polymer liquid crystal film or the like can be used in addition to the cholesteric liquid crystal cell as in the embodiment. Further, it is needless to say that the same effect can be obtained even if the liquid crystal display device to be used is one other than the TN, VAN, and STN types as long as the liquid crystal display device obtains the action of the present invention (that controls polarization). Absent.

[0052]

According to the present invention, since the element and the member can be made of a thin film-like plate, it is possible to realize a linear polarizing device and a liquid crystal display device which are compact and lightweight as a whole. A light and small liquid crystal display device can be realized. In addition, both are easy to make and the manufacturing cost is low. Furthermore, since the light of the required wavelength is efficiently converted into linearly polarized light, the display characteristics (contrast ratio, etc.) obtained are excellent. In particular, when a switching element such as a TFT is provided in the liquid crystal cell used, a liquid crystal display device having a large display capacity can be realized.

[Brief description of drawings]

FIG. 1 is a layout diagram illustrating a configuration of an embodiment of the present invention.

FIG. 2 is a layout diagram for explaining the operation of light control of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... 1st selective reflection liquid crystal element 2 ... 1/4 wavelength phase difference plate 3 ... Mirror 4 ... 1/4 wavelength phase difference plate 5 ... Mirror 6 ... 2nd selective reflection liquid crystal element

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuko Fukuoka 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa Stock company, Toshiba Yokohama Works (72) Inventor Hitoshi Hato 8 Shinsugita-cho, Isogo-ku, Yokohama, Kanagawa Company Toshiba Yokohama Office

Claims (6)

[Claims] 1. A unidirectional circularly polarized first circularly polarized light that selectively reflects incident light of a specific wavelength in the direction of the first optical path and travels along the first optical path, and the incident light as a second A first selective reflection liquid crystal element which selectively transmits in the direction of the second direction and travels in the second optical path to be separated into the second circularly polarized light of the other direction, and the first selective reflection liquid crystal element which is located on the first optical path First quarter-wave retarder for converting the circularly polarized light of the first linearly polarized light into the first linearly polarized light and the second linearly polarized light of the second circularly polarized light located on the second optical path. And a second quarter-wave retarder that converts the light into a first linearly polarized light from the first optical path and a second linearly polarized light from the second optical path that reflects the first linearly polarized light. A linear polarization device comprising a second selective reflection liquid crystal element for synthesizing linearly polarized light to obtain a third linearly polarized light. 2. The linear polarization device according to claim 1, wherein the incident light is light having a peak wavelength in any one of red, green and blue. 3. A first circularly polarized light that selectively reflects incident light and travels along a first optical path and a second circularly polarized light that selectively transmits and travels through a second optical path. A selective reflection liquid crystal element,
The first circularly polarized light is located on the first optical path,
A first quarter-wave retarder that converts the linearly polarized light of
The second circularly polarized light is located on the second optical path and
A second quarter-wave retarder that converts the linearly polarized light of
The first linearly polarized light from the first optical path is transmitted, the second linearly polarized light from the second optical path is reflected, and the linearly polarized light is combined to obtain a third linearly polarized light. A linear polarization device including a second selective reflection liquid crystal element, a polarization control liquid crystal device that receives a third linearly polarized light and controls the polarized light to be emitted light, and an analyzer arranged on the optical path of the emitted light. A liquid crystal display device including a polarizing device that operates as a device. 4. Three sets of combinations of an incident light polarization device and a polarization control liquid crystal device respectively corresponding to red wavelength light, green wavelength light and blue wavelength light are provided, and output lights emitted from these sets are combined. 4. The liquid crystal display device according to claim 3, wherein the liquid crystal display device passes through an outgoing light polarization device that operates as an analyzer. 5. The liquid crystal display device according to claim 3, wherein the polarization control liquid crystal device is a TN type liquid crystal device. 6. A liquid crystal display device comprising at least one polarization control type liquid crystal display cell, and a linear polarization device which makes linearly polarized light incident on the polarization control type liquid crystal display cell,
The linear polarization device allows a cholesteric liquid crystal cell or a polymer liquid crystal film that selectively reflects the peak wavelength λm of incident light to obtain circularly polarized reflected light and transmitted light, and makes light having a peak wavelength λm enter, [{ (1 + 2k) / 4}
[lambda] m] (k = 0,1,2, ...) Acting as a retardation to transmit the circularly polarized reflected light and the transmitted light, respectively, and make the respective transmitted light into linearly polarized light, a 1/4 wavelength phase difference. A plate and one of these linearly polarized lights are selectively reflected and one of them is transmitted to combine the respective linearly polarized lights into linearly polarized lights having the same polarization axis.
A liquid crystal display device comprising: a cholesteric liquid crystal cell or a polymer liquid crystal film that selectively reflects m, and causes the synthesized linearly polarized light to enter the polarization control type liquid crystal display cell.