JPH11249074A - Polarizing element and reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizing element with which light transmittance is improved. SOLUTION: A polarizing element 1 is provided with a polarizing plate 2, non-birefringent transmissible substrate 3 arranged on one surface side of this polarizing plate 2, and plural stripe-shaped birefringence parts 4 formed on the substrate 3 and composed of birefringent dielectrics. The birefringence parts 4 are mutually parallel and arranged at equal intervals. The direction of this arrangement is equal with the polarizing direction of light passed through the polarizing plate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a polarizing element having improved light transmittance and a reflection type liquid crystal display device using the same.

[0002]

2. Description of the Related Art A liquid crystal display device such as a liquid crystal display has
Because of its excellent features such as light weight and thinness, AV equipment such as small cameras, video cameras, digital cameras,
Currently, it is widely used as a display for OA equipment such as a word processor and a personal computer.

However, in the conventional liquid crystal display device, there is a problem to be improved such that a backlight is required because light use efficiency is as low as several percent, and power consumption is increased. In response to such a problem, a reflection type liquid crystal display device using natural light has been proposed, and an electric field control birefringence type liquid crystal display device and the like have been put to practical use.

[0004]

By the way, in the liquid crystal display device of the electric field control birefringence type, the electro-optical modulation is performed by disposing a polarizing plate on the front side of the liquid crystal panel. However, such a polarizing plate absorbs about one-half of the light transmitted through the polarizing plate. As a result, in a liquid crystal display device equipped with this polarizing plate, the light utilization efficiency is only about 40%, and sufficient brightness is obtained. Complained that it was not possible to get a display of the height.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a polarizing element having improved light transmittance and a reflective liquid crystal display device having the same.

[0006]

It is well known that when light enters a medium made of a dielectric, polarized light may be generated. For example, as shown in FIG. 3, when non-polarized light is incident on the medium B made of a dielectric material from the medium A made of a dielectric material, most of the S-polarized light component is reflected at the interface between the media, and the P-polarized light component is Many of them pass through the interface and pass through the medium B. Such a phenomenon is particularly remarkable when θp is an angle called a Brewster angle (tan θp = n _B / n _A ). At this time, the reflected light is completely an S-polarized component, and the transmitted light is completely a P-polarized component. Becomes

The polarizing element of the present invention is made by utilizing such a principle, and comprises a polarizing plate and a light-transmitting substrate having no birefringence disposed on one side of the polarizing plate. A plurality of stripe-shaped birefringent portions formed of a dielectric material having birefringence, formed on the substrate, wherein the birefringent portions are arranged parallel and at equal intervals, and the arrangement direction is The present invention has been made to solve the above problem, in that the polarization direction of the light transmitted through the polarizing plate is the same as the polarization direction.

According to the polarizing element of the present invention, the birefringent portions are arranged in parallel with each other and at equal intervals, and the arrangement direction is the same as the polarization direction of the light transmitted through the polarizing plate. Of the light incident on the side wall of the part, the polarized light component which becomes S-polarized light with respect to the birefringent part is reflected on the side wall and is incident on the polarizing plate. At this time, the light reflected on the side wall of the birefringent portion and incident on the polarizing plate passes through the polarizing plate because its polarization direction matches the polarization direction of the polarizing plate.

On the other hand, of the light incident on the side wall of the birefringent part, the polarized light component which becomes P-polarized light with respect to the birefringent part is refracted on the side wall and most of the light enters the birefringent part. At this time, since the birefringent part has birefringence, even when it is P-polarized light at the time of entering the birefringent part, an S-polarized light component is generated by birefringence while propagating through the birefringent part. . Therefore, the polarization component (S-polarized light) parallel to the polarization axis of the polarizing plate is generated in the P-polarized light component which is originally cut by the polarizing plate provided below the birefringent portion. The light passing through is generated.

In the reflection type liquid crystal display device according to the present invention, the polarizing element is disposed on the front side of the liquid crystal panel. According to this reflection type liquid crystal display device, by arranging the polarizing element, light passing through the polarizing plate is generated from the light of the polarization component that would otherwise be cut by the polarizing element, Therefore, light use efficiency is improved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below. FIG. 1 is a view showing one embodiment of the polarizing element of the present invention.
Reference numeral 1 denotes a polarizing element. The polarizing element 1 includes a polarizing plate 2, a substrate 3 disposed on one surface side of the polarizing plate,
A plurality of stripe-shaped birefringent portions 4 formed on the substrate 3 are provided.

The polarizing plate 2 has a well-known structure generally used in the prior art, and includes an iodine-based polarizer made of polyvinyl alcohol which is uniaxially stretched by enclosing polyiodide ions and a uniaxially stretched polyvinyl alcohol. It is formed by laminating a cellulose triacetate film or a protective film on a dye-based polarizer in which a water-soluble dichroic dye is bound with its affinity. The polarizing plate 2 transmits light of a polarization component in the same direction as the uniaxially stretched direction, and absorbs light of a polarization component in a direction orthogonal to the uniaxially stretched direction.

The substrate 3 is made of a translucent material having no birefringence. The birefringent portions 4 have a substantially square cross section made of a dielectric material having birefringence, and are formed on the substrate 3 in a state of being arranged in parallel with each other and at equal intervals. These birefringent parts 4 are arranged in the following directions:
The polarizing plate 2 is formed and arranged so as to have the same polarization direction as light transmitted therethrough.

In the polarizing element 1 having such a configuration,
For example, when incorporated and used in a reflection type liquid crystal display device of an electric field control birefringence type, as shown in FIG. Used.

In such a reflection type liquid crystal display device, the polarizing element 1 is formed and arranged so that the arrangement direction of the birefringent portions 4 is the same as the polarization direction of the light transmitted through the polarizing plate 2. As shown by an arrow in FIG.
Most of the polarized light component, which becomes S-polarized light with respect to the birefringent portion 4 of the light incident on a, is reflected by the side wall 4a, passes through the substrate 3, and is incident on the polarizing plate 2. Then, the light incident on the polarizing plate 2 in this manner passes through the polarizing plate 2 and is incident on the liquid crystal panel because the polarization direction of the light matches the polarization direction of the polarizing plate 2.

On the other hand, of the light incident on the side wall 4a of the birefringent part 4, the polarization component which becomes the P-polarized light with respect to the birefringent part 4 is as follows:
Most of the light is refracted by the side wall 4 a and enters the birefringent part 4. Then, since the birefringent part 4 is provided with birefringence, even if the light incident on the birefringent part 4 is P-polarized light at the time of incidence, the light will be propagated through the birefringent part 4 from now on. S-polarized light component is generated by birefringence.

Therefore, a polarization component (S-polarized light) parallel to the polarization axis of the polarizing plate 2 is generated in the P-polarized light component which is originally cut by the polarizing plate 2 below the birefringent portion 4.
Light passing through the polarizing plate 2 is generated, and as a result, the liquid crystal panel 5
Is increased as compared with the case where only the polarizing plate 2 is simply disposed without providing the birefringent portion 4 as in the related art.

Therefore, in the polarizing element 1 of the present invention,
The light transmittance can be increased as compared with a conventional configuration including only a polarizing plate, thereby improving the light use efficiency. Further, even in a reflection type liquid crystal display device using such a polarizing element 1, the polarizing element 1 generates light that passes through the polarizing plate 2 from light of a polarized component that would otherwise be cut. , The light use efficiency can be improved.

[0019]

As described above, in the polarizing element of the present invention, the birefringent portions are arranged parallel to each other and at equal intervals, and the arrangement direction is the same as the polarization direction of the light transmitted by the polarizing plate. With such a configuration, of the light incident on the side wall of the birefringent part, most of the polarized light component that becomes S-polarized light with respect to the birefringent part is reflected by the side wall and made incident on the polarizing plate. Then, the light incident on the polarizing plate in this way passes through the polarizing plate because its polarization direction matches the polarization direction of the polarizing plate.

On the other hand, of the light incident on the side wall of the birefringent part, the polarized light component that becomes P-polarized light with respect to the birefringent part is refracted on the side wall and most of the light enters the birefringent part. Then, since the birefringent part is provided with birefringence, even if the light incident on the birefringent part is P-polarized light at the time of incidence, it will be birefringent while propagating through the birefringent part. An S-polarized component is generated.

Therefore, the P-polarized light, which is originally cut by the polarizing plate below the birefringent portion, has a polarization component (S-polarized light) parallel to the polarization axis of the polarizing plate, and passes through the polarizing plate. As a result, compared to a case where only a polarizing plate is simply arranged without providing a birefringent portion as in the related art,
The amount of light transmitted through the polarizing plate can be increased, and thereby the light use efficiency can be increased.

In the reflection type liquid crystal display device of the present invention, since the above-mentioned polarizing element is arranged on the front side of the liquid crystal panel, the light of the polarization component which would otherwise be cut passes through the polarizing plate. Light is generated, and thus the light utilization efficiency is increased. Therefore, if this liquid crystal display device is applied to, for example, a liquid crystal projector, display brightness can be improved.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a schematic configuration of a polarizing element of the present invention.

FIG. 2 is a side sectional view showing a schematic configuration of a reflection type liquid crystal display device of the present invention.

FIG. 3 is a principle diagram for explaining the operation of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Polarizing element, 2 ... Polarizing plate, 3 ... Substrate, 4 ... Birefringent part,
4a: Side wall, 5: Liquid crystal panel

Claims (2)

[Claims] 1. A polarizing plate, a light-transmitting substrate having no birefringence disposed on one surface side of the polarizing plate, and a birefringent dielectric formed on the substrate. A plurality of stripe-shaped birefringent portions, wherein the birefringent portions are arranged parallel to each other and at equal intervals, and the arrangement direction is the same as the polarization direction of light transmitted by the polarizing plate. A polarizing element, characterized in that: 2. A reflection type liquid crystal display device of an electric field control birefringence type, comprising: a polarizing plate on a front side of a liquid crystal panel; and a translucent material having no birefringence disposed on one side of the polarizing plate. A substrate, formed on the substrate, comprising a plurality of stripe-shaped birefringent portions made of a dielectric material having birefringence, wherein the birefringent portions are arranged in parallel with each other and at equal intervals, this arrangement A reflection type liquid crystal display device, wherein a polarizing element whose direction is the same as the polarization direction of light transmitted through the polarizing plate is arranged.