JP2003222726A - Optical element and display apparatus using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a display apparatus capable of obtaining bright reflection display. <P>SOLUTION: An optical film 20 having a characteristic for straightly directing and transmitting one of two orthogonal polarization components of an incident light and refracting and transmitting the other is disposed on a front side as an observed side of display of a liquid crystal element 10 for controlling a polarization state of a transmitted light. An optical element 1 comprising an optical layer 2 having the characteristic for straightly directing and transmitting one of two orthogonal polarization components of the incident light and refracting and transmitting the other, a reflection film 6 disposed opposite to one face of the optical layer 2 and a plurality of light absorbing walls 7 disposed substantially perpendicular to the reflection film 6 at intervals in the plate direction of the reflection film 6 between the optical layer 2 and the reflection film 6 is disposed on a back side of the liquid crystal element 10 so as to place the optical layer 2 opposite to the liquid crystal element 10. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical element and a reflective display device using the same.

[0002]

2. Description of the Related Art As a display device using a polarization control element for controlling the polarization state of transmitted light, a reflection device for displaying the light incident from the front side, which is the observation side of the display, is reflected by a reflecting means provided on the rear side. There is a type.

This reflection type display device includes, for example, a polarization control element such as a liquid crystal element, a front side polarizing plate and a rear side polarizing plate arranged with the polarization control element sandwiched therebetween, and a rear side polarizing plate. It consists of a reflector.

In this reflection type display device, the light incident from the front side, which is the viewing side of the display, is made incident on the polarization control element as linearly polarized light along the transmission axis by the front side polarizing plate,
Of the light whose polarization state is controlled by the polarization control element and which is emitted to the rear side, the light of the polarization component along the absorption axis of the rear side polarizing plate is absorbed by this rear side polarizing plate, The light of the polarization component along the transmission axis is transmitted through the rear side polarizing plate and reflected by the reflecting plate, and the reflected light is transmitted through the rear side polarizing plate, the polarization control element and the front side polarizing plate to the front side. The image is displayed by emitting.

[0005]

However, in the above-mentioned conventional reflection type display device, the polarizing plates disposed on the front side and the rear side of the polarization control element respectively absorb the light of the polarization component along the absorption axis thereof. Since the light of the polarized component along the transmission axis is transmitted, the light transmittance is low and a bright display cannot be obtained.

The present invention provides an optical element capable of forming a bright display type display device by arranging it on the rear side of a polarization control element, and a reflection type display device using the optical element. It is intended to be provided.

[0007]

The optical element of the present invention comprises:
Of the two polarization components of the incident light which are orthogonal to each other, one of the optical layers and an optical layer having a characteristic of straightening and transmitting one polarization component and refracting and transmitting the other polarization component Between the optical film and the reflective film, the reflective film being disposed so as to face the surface of the reflective film, and being disposed substantially vertically to the reflective film with a space in the surface direction of the reflective film. It is characterized by comprising a plurality of light absorbing walls.

In this optical element, the optical layer allows the light of one polarization component of the two polarization components of the incident light which are orthogonal to each other to go straight and to transmit, and the light of the other polarization component to refract and transmit. Therefore, of the light incident from the direction along the normal of the optical layer, the light of one polarization component that has passed straight through the optical layer and is transmitted is reflected by the light absorption walls. The light of the other polarization component that is reflected by the film, goes straight through the optical layer again, passes through the optical layer, and refracts through the optical layer, and the light of the other polarization component enters the light absorbing wall and is absorbed. Of the light incident from the direction inclined with respect to the normal to the optical layer, the light of one polarization component that has passed straight through the optical layer and is transmitted is incident on the light absorbing wall and absorbed, Along the normal line of the other polarized light that is refracted and transmitted Is reflected by the reflective film light refracted in the direction through between the plurality of light absorbing walls, light refracted in a direction inclined with respect to the normal line is absorbed incident on the light absorption wall.

That is, this optical element has a characteristic of reflecting light of one polarization component and absorbing light of the other polarization component with respect to light incident from a direction along the normal line of the optical layer. For the light incident from a direction inclined with respect to the normal line of the optical layer, the light of one polarization component is absorbed and a part of the light of the other polarization component is reflected. It exhibits the property of absorbing other light.

Therefore, the reflectance of light can be changed by controlling the incident directions of the light of one polarization component and the light of the other polarization component which are incident on the optical element. The polarization state is controlled by the polarization control element by arranging the polarization control element on the rear side of the polarization control element for controlling the polarization state of the transmitted light so that the reflectance of light incident from the front side of the polarization control element and incident on the optical element is controlled by the polarization control element. It is possible to perform reflective display which is changed by.

Since this optical element reflects both the light of the one polarization component and the light of the other polarization component,
The reflectance of light is higher than that in which a reflection plate is arranged on the rear side of the polarizing plate, and therefore a reflection type display device having a bright display can be constructed.

As described above, in the optical element of the present invention, of the two polarization components of the incident light which are orthogonal to each other, the light of one polarization component is made to go straight and transmitted, and the light of the other polarization component is refracted. A reflective film is arranged so as to face one surface of an optical layer having a property of transmitting, and the optical film and the reflective film are spaced apart from each other in the surface direction of the reflective film with respect to the reflective film. By arranging a plurality of light absorbing walls substantially vertically, the light reflectance can be changed by controlling the incident directions of the light of one polarization component and the light of the other polarization component that enter the optical element. , The light is reflected with a high reflectance. Therefore, by arranging this optical element on the rear side of the polarization control element for controlling the polarization state of the transmitted light, a bright reflection type display device for display is provided. Can be configured Kill.

In the optical element of the present invention, the optical layer has a prism sheet having a plurality of elongated prism portions densely arranged on one surface and formed in parallel with each other, and a refractive index larger than that of the prism sheet. And a high refractive index layer provided on one surface of the prism sheet so as to cover the plurality of elongated prism portions.

In this case, the high refractive index layer of the optical layer comprises a liquid crystal polymer layer in which liquid crystal molecules are aligned with their long axes aligned in a direction substantially parallel to the length direction of the elongated prism portion of the prism sheet. Is desirable.

Further, in this optical element, the light absorbing wall is composed of a cylindrical body having an inner surface as a light absorbing surface, and the plurality of cylindrical light absorbing walls are arranged in the surface direction of the reflecting film. It is preferable that they are closely arranged.

Further, in the display device of the present invention, the polarization control element for controlling the polarization state of the transmitted light and the light of one polarized component of the two polarized components of the incident light which are orthogonal to each other are allowed to go straight and be transmitted. , An optical film having a characteristic of refracting and transmitting the light of the other polarization component, which is arranged on the front side which is the viewing side of the display of the polarization control element, and two polarization components of the incident light which are orthogonal to each other. An optical layer having a characteristic of allowing light of one polarization component to go straight forward and transmitting, and refracting and transmitting light of the other polarization component, and a reflection film arranged to face one surface of the optical layer. , A plurality of light absorbing walls disposed between the optical layer and the reflective film in a plane direction of the reflective film and being substantially perpendicular to the reflective film. The optical layer is provided on the rear side of the device to control the polarization. An optical element arranged to face the child, is characterized in that it comprises a.

That is, in this display device, an optical film having the same characteristics as the optical layer of the above-mentioned optical element of the invention is arranged on the front side, which is the viewing side of the display, of the polarization control element for controlling the polarization state of transmitted light. , The light of one polarization component and the light of the other polarization component incident on the optical element by arranging the optical element on the rear side of the polarization control element with its optical layer facing the polarization element. The incident direction of is controlled by the optical film and the polarization control element to perform reflective display in which the reflectance of light by the optical element is changed.

According to this display device, since the optical element reflects both the light of one polarization component and the light of the other polarization component as described above, a bright reflective display can be obtained.

As described above, in the display device of the present invention, one of the two polarization components of the incident light, which are orthogonal to each other, travels straight to the front side, which is the viewing side of the display of the polarization control element. Is transmitted, and an optical film having a characteristic of refracting and transmitting the light of the other polarization component is arranged, and on the rear side of the polarization control element, the optical element of the invention described above,
By arranging the optical layer so as to face the polarizing element, a bright reflective display can be obtained.

In this display device, the polarization control element includes liquid crystal molecules at a twist angle of substantially 90 ° between a front substrate, which is the viewing side of the display, and a rear substrate, which faces the front substrate. A liquid crystal element provided with a twist-oriented liquid crystal layer, the optical film arranged on the front side of the liquid crystal element, a prism sheet in which a plurality of elongated prism portions are densely arranged on one surface in parallel with each other. A high refractive index layer having a refractive index larger than that of the prism sheet, the high refractive index layer being provided on the one surface of the prism sheet to cover the plurality of elongated prism portions. The optical layer of the optical element disposed on the side has a prism sheet in which a plurality of elongated prism portions are densely arranged on one surface and formed in parallel with each other, and a refractive index larger than the refractive index of the prism sheet. And a high refractive index layer provided on the one surface of the prism sheet to cover the plurality of elongated prism portions, wherein the optical film and the optical element are prism sheets of the optical film. It is preferable that the longitudinal direction of the elongated prism portion and the longitudinal direction of the elongated prism portion of the prism sheet of the optical layer of the optical element are substantially orthogonal or parallel to each other.

[0021]

1 to 7 show an embodiment of an optical element of the present invention, and FIG. 1 is a sectional view of a part of the optical element.

As shown in FIG. 1, the optical element 1 of this embodiment allows one of the two polarized light components of the incident light, which are orthogonal to each other, to go straight through and transmit the light of the other polarized light component. Optical layer 2 having the property of refracting and transmitting light
And a plurality of light absorption walls 7 arranged between the optical layer 2 and the reflection film 6. The reflection film 6 is arranged so as to face one surface of the optical layer 2.

The optical layer 2 has a prism sheet 3 in which a plurality of elongated prism portions 4 are densely arranged on one surface and formed in parallel with each other, and a refractive index higher than that of the prism sheet 3. The high refractive index layer 5 is provided on one surface of the prism sheet 3 so as to cover the plurality of elongated prism portions 4.

The prism sheet 3 is made of an optically isotropic transparent resin, for example, an acrylic resin having a refractive index of 1.511, and one surface thereof, that is, the high refractive index layer 5 is provided. A plurality of linear elongated prism parts 4 on the surface
Are densely arranged at a very small pitch of about 25 μm to 100 μm and are formed parallel to each other, and the outer surface which is the other surface is formed as a flat surface.

Each of the plurality of elongated prism portions 4 of the prism sheet 3 has an isosceles triangular cross section, and two slanted surfaces 4a and 4b of the elongated prism portion 4 are provided.
The inclination angle of each is 45 ° (see FIGS. 2 and 3).

The high refractive index layer 5 is optically anisotropic and has a refractive index of the prism sheet 3 in a direction substantially parallel to the length direction of the elongated prism portion 4 of the prism sheet 3. It has a characteristic larger than the refractive index.

The high refractive index layer 5 is composed of, for example, a liquid crystal polymer layer in which liquid crystal molecules are aligned with their major axes aligned in a direction substantially parallel to the length direction of the elongated prism portion 4 of the prism sheet 3. ing. Hereinafter, this high refractive index layer 5 is referred to as a liquid crystal polymer layer.

The liquid crystal polymer layer 5 is filled with polymer liquid crystal in the concave portions between the plurality of elongated prism portions 4 of the prism sheet 3, and the liquid crystal molecules are arranged along the length direction of the elongated prism portions 4. It is formed by polymerizing in a state of being arranged.

In this embodiment, the liquid crystal polymer layer 5 is formed thicker than the depth of the concave portions between the plurality of elongated prism portions 4 of the prism sheet 3 so that the outer surface thereof becomes a continuous flat surface. However, the liquid crystal polymer layer 5 has a plurality of elongated prism portions 4 of the prism sheet 3.
The outer surface of the liquid crystal polymer layer 5 may be formed so as to be flush with the top of the elongated prism portion 4 in each of the recesses between the two.

The liquid crystal polymer layer 5 is optically anisotropic because the liquid crystal molecules are aligned so that their long axes are aligned in a direction substantially parallel to the lengthwise direction of the elongated prism portion 4. And the refractive index in the direction along the alignment direction of the liquid crystal molecules, that is, in the direction substantially parallel to the lengthwise direction of the elongated prism portion 4 of the prism sheet 3, is the prism sheet 3.
Greater than the refractive index of.

The refractive index in the direction orthogonal to the liquid crystal molecule alignment direction of the liquid crystal polymer layer 5, that is, in the direction substantially orthogonal to the length direction of the elongated prism portion 4 of the prism sheet 3, is the prism sheet 3. Is substantially the same as the refractive index of.

That is, the refractive index of the liquid crystal polymer layer 5 in the direction substantially parallel to the lengthwise direction of the elongated prism portion 4 is 1.663, which is substantially equal to the lengthwise direction of the elongated prism portion 4. The refractive index in the orthogonal direction is 1.511.

The optical layer 2 has an optically isotropic prism sheet 3 and the prism sheet 3 having a refractive index in a direction substantially parallel to the longitudinal direction of the elongated prism portion 4 of the prism sheet 3. And a liquid crystal polymer layer 5 having a refractive index in the direction substantially orthogonal to the length direction of the elongated prism portion 4 that is substantially the same as the refractive index of the prism sheet 3 Therefore, of the two polarization components of the incident light which are orthogonal to each other, one polarization component along a direction substantially orthogonal to the lengthwise direction of the elongated prism portion 4 (hereinafter, referred to as a polarization component in the x direction). ) Is transmitted straight and transmitted, and the other polarization component (hereinafter, y) along a direction substantially parallel to the lengthwise direction of the elongated prism portion 4 is transmitted.
Direction (referred to as the polarization component) is refracted and transmitted.

FIG. 2 shows the normal line of the optical layer 2 (the normal line of the outer surface of the prism sheet 3 and the outer surface of the liquid crystal polymer layer 5) h.
1 is a diagram showing a transmission path of light incident from a direction along 1; FIG. 3 is substantially orthogonal to the normal direction h1 of the optical layer 2 with respect to the longitudinal direction of the elongated prism portion 4 of the prism sheet 3. It is a figure which shows the transmission path of the light which injected from the direction which inclined to the direction, and all have shown the transmission path of the light which entered from the outer surface of the said liquid crystal polymer layer 5.

As shown in FIGS. 2 and 3, of the light incident on the optical layer 2 from the outer surface of the liquid crystal polymer layer 5, the light is substantially orthogonal to the longitudinal direction of the elongated prism portion 4 of the prism sheet 3. The light X of the polarization component in the x direction having a vibrating surface in the direction is the liquid crystal polymer layer 5 and the prism sheet 3.
In a direction substantially parallel to the lengthwise direction of the elongated prism portion 4, passing through the interfaces with the inclined surfaces 4a and 4b of the plurality of elongated prism portions 4 without refracting, and exiting from the outer surface of the prism sheet 3. The light Y of the polarization component in the y direction having the vibrating surface is refracted at the interface between the liquid crystal polymer layer 5 and the inclined surfaces 4a and 4b of the plurality of elongated prism portions 4, and is emitted from the outer surface of the prism sheet 3. To do.

The outgoing direction of the light transmitted through the optical layer 2 is
It depends on the incident angle to the optical layer 2 and the polarization direction.

That is, focusing on the light incident on the optical layer 2 at an incident angle of 0 ° parallel to the normal line h1, the light X of the polarization component in the x direction is shown in FIG. As described above, the interface between the liquid crystal polymer layer 5 and the outside air (air), the interface between the liquid crystal polymer layer 5 and the inclined surfaces 4a and 4b of the elongated prism portion 4, and the interface between the prism sheet 3 and the outside air. And are transmitted without refraction, and are emitted in a direction parallel to the normal line h1 at an emission angle of 0 °.

Further, as described above, the inclination angles of the two inclined surfaces 4a and 4b of the elongated prism portion 4 are 45, respectively.
And the refractive index of the optically isotropic prism sheet 3 is 1.511, and the refractive index of the liquid crystal polymer layer 5 in the direction substantially parallel to the lengthwise direction of the elongated prism portion 4 is 1. Therefore, the light Y of the polarization component in the y direction out of the light incident at the incident angle of 0 ° is 0.663, as shown in FIG.
The light is refracted in the direction of 5.02 ° at the interfaces with the inclined surfaces 4a and 4b, and is further refracted in the direction of 8.37 ° at the interface between the prism sheet 3 and the outside air.

The light Y refracted at the interface between the liquid crystal polymer layer 5 and one inclined surface 4a of the elongated prism portion 4 is used.
And the direction of emission of the light Y refracted at the interface with the other inclined surface 4b are opposite to each other with the normal line h1 as a boundary, and in the figure, the direction to the left of the normal line h1 is shown. When the angle is − and the rightward angle is +, the light is refracted at the interface between the liquid crystal polymer layer 5 and the −45 ° inclined surface (the left inclined surface in the figure) 4a of the elongated prism portion 4. The light Y is in the direction of + 8.37 ° with respect to the normal line h1 from the outer surface of the prism sheet 3 (rightward in the figure).
The liquid crystal polymer layer 5 and the slender prism portion 4 at an inclined surface of + 45 ° (the inclined surface on the right side in the drawing) 4b.
The light Y refracted at the interface with is emitted from the outer surface of the prism sheet 3 in the direction of −8.37 ° with respect to the normal line h1 (left direction in the drawing).

Further, light incident on the optical layer 2 from a direction inclined with respect to the normal line h1 in a direction substantially orthogonal to the length direction of the elongated prism portion 4 of the prism sheet 3,
For example, focusing on the light incident at an incident angle of −8.37 ° with respect to the normal line h1, the light X of the polarization component in the x direction out of the light is the liquid crystal as shown in FIG. The interface between the polymer layer 5 and the outside air refracts in the direction of + 5.53 ° and enters the liquid crystal polymer layer 5, and refracts the interface between the liquid crystal polymer layer 5 and the inclined surfaces 4a and 4b of the elongated prism portion 4. Without passing through, the light is refracted in the direction of + 8.37 ° at the interface between the prism sheet 3 and the outside air, and is emitted in a direction parallel to the incident direction to the optical layer 2.

On the other hand, of the light incident on the optical layer 2 at the incident angle of −8.37 ° with respect to the normal line h1, the light Y of the polarization component in the y direction is as shown in FIG. Then, the light is refracted in the direction of + 5.02 ° at the interface between the liquid crystal polymer layer 5 and the outside air and enters the liquid crystal polymer layer 5.

Of the incident light Y, the light incident on the interface between the liquid crystal polymer layer 5 and the −45 ° inclined surface 4a of the elongated prism portion 4 is refracted in the direction of 0 ° at the interface. , Passes through the interface between the prism sheet 3 and the outside air without refraction, and exits in a direction parallel to the normal line h1.

Further, of the incident light Y, the liquid crystal polymer layer 5 and the slanted surface 4 of the elongated prism portion 4 at + 45 °.
The light incident on the interface with b is refracted in the direction of + 12.5 ° at the interface, and further refracted at the interface between the outer surface of the prism sheet 3 and the outside air and emitted in the direction of + 19.09 °.

In the y direction which is incident on the optical layer 2 from a direction inclined at −8.37 ° in a direction substantially orthogonal to the length direction of the elongated prism portion 4 of the prism sheet 3 with respect to the normal line h1 thereof. 2 of the elongated prism part 4 of the light Y of the polarization component
The incidence rates on the two inclined surfaces 4a and 4b have the following relationship.

That is, as shown in FIG. 3, the y-direction is incident from a direction inclined by −8.37 ° in a direction substantially orthogonal to the length direction of the elongated prism portion 4 with respect to the normal line h1. In the light Y of the polarization component of, the width of the transmission region of the light incident on the −45 ° inclined surface 4a is c, and the width of the transmission region of the light incident on the + 45 ° inclined surface 4a is d. Assuming that the sum of the widths c and d of both areas, that is, the pitch of the plurality of elongated prism portions 4 is 1, the widths c and d of the respective areas
Is represented by the following equation.

C = (1 + tan 5.02 °) / 2 (1) d = (1-tan 5.02 °) / 2 (2) Therefore, y incident from the direction inclined at −8.37 °
Assuming that the amount of light Y of the polarization component in the direction is 100%, the ratio of the light incident on the −45 ° inclined surface 4a of the elongated prism unit 4 is {(1 + tan 5.02 °) / 2} × 100≈54. .4% (3) The proportion of light incident on the + 45 ° inclined surface 4b of the elongated prism portion 4 is {(1-tan 5.02 °) / 2} × 100≈45.6% (4) Becomes

As described above, the light incident on the −45 ° inclined surface 4a is refracted in the direction of 0 ° at the interface between the liquid crystal polymer layer 5 and the inclined surface 4a, and the normal line h1.
Light emitted in a direction parallel to and incident on the + 45 ° inclined surface 4b is refracted at the interface between the liquid crystal polymer layer 5 and the inclined surface 4b and the interface between the outer surface of the prism sheet 3 and the outside air. Since it is emitted in the direction of + 19.09 °, about 54.4% of the light Y of the polarization component in the y direction that is incident from the direction inclined by −8.37 ° has the emission angle of 0 °. The light is emitted in a direction parallel to the normal line h1, and about 45.6% of the other light is emitted in a direction of + 19.09 °.

2 and 3 show the transmission paths of the light incident on the optical layer 2 from the outer surface of the liquid crystal polymer layer 5, the optical layer 2 enters from the outer surface of the prism sheet 3. It exhibits the same characteristics with respect to irradiated light.

That is, as can be seen by reversing the transmission paths shown in FIGS. 2 and 3, the optical layer 2 is
Even with respect to the light incident from the outer surface of the prism sheet 3, the light X of the polarization component in the x direction along the direction substantially orthogonal to the length direction of the elongated prism portion 4 of the prism sheet 3 is made to travel straight. The light Y of the polarization component in the y direction along the direction substantially parallel to the length direction of the elongated prism portion 4 is refracted and transmitted.

Also in this case, the liquid crystal polymer layer 5 when the incident angle of light from the outer surface of the prism sheet 3 is 0 °
The emission angle of the polarization component X in the x direction from the outer surface of the is 0 °, and the emission angle of the polarization component Y in the y direction is −8.37 ° or +8.3.
7 °, and when the incident angle of light from the outer surface of the prism sheet 3 is −8.37 °, the exit angle of the polarization component X in the x direction from the outer surface of the liquid crystal polymer layer 5 is + 8.37 °,
The emission angles of the polarization component Y in the y direction are 0 ° and + 19.09 °, and the relationship between the incident angle and the emission angle is that when light is incident from the outer surface of the liquid crystal polymer layer 5 as shown in FIGS. 2 and 3. Is the same as.

The reflection film 6 is a specular reflection film,
The reflection film 6 is arranged on one surface side of the optical layer 2, for example, the outer surface side of the prism sheet 3 in parallel with the outer surface of the prism sheet 3, and the light absorption wall (hereinafter, referred to as absorption wall) 7 Are arranged between the optical layer 2 and the reflection film 6 with a gap in the surface direction of the reflection film 6 substantially perpendicular to the reflection film 6.

FIG. 4 is a perspective view of the reflection film 6 and a plurality of light absorption walls 7, FIG. 5 is an enlarged perspective view of one light absorption wall 7, and FIG. 6 is a view of the reflection film 6 and a plurality of light absorption walls 7. It is an expanded sectional view.

As shown in FIGS. 4 and 5, the absorption wall 7 is made of a cylindrical body having an inner peripheral surface serving as a light absorption surface 7a. The reflective film 6
Are arranged closely side by side.

The optical system composed of the reflection film 6 and the plurality of absorption walls 7 is along the normal line (not shown) of the reflection film 6 in the light incident from the front side facing the optical layer 2. Light incident from a direction is reflected and emitted to the front side, and light incident from a direction inclined with respect to the normal line is absorbed.

That is, of the light incident on the optical system from its front side, the light incident at an incident angle within a predetermined angle range from the direction along the normal line of the reflection film 6 is indicated by a solid arrow in FIG. As shown in, the light is reflected by the reflective film 6 through the spaces between the plurality of absorption walls 7 and again enters the optical layer 2 through the spaces between the plurality of absorption walls 7, The light is emitted from the outer surface of the liquid crystal polymer layer 5 of the optical layer 2.

Of the light incident on the front side of this optical system, the light incident at an incident angle larger than the angle range with respect to the normal line of the reflection film 6 is shown by a broken line arrow in FIG. As described above, the light is directly incident on the absorption wall 7, or
It is obliquely reflected by the reflective film 6 through the space between the plurality of absorption walls 7, enters the absorption wall 7, and is absorbed by the absorption wall 7.

The angle of incidence of light on the optical system composed of the reflective film 6 and the plurality of absorption walls 7 and the emission rate of light reflected by the reflective film 6 and emitted (hereinafter referred to as reflectance). The relationship is determined by the ratio of the interval a of the absorption wall 7 (the inner diameter of the cylindrical body whose inner peripheral surface is the light absorption surface 7a) and the height b of the absorption wall 7.

In this embodiment, the ratio of the distance a to the height b of the absorbing wall 7 is 1: 3.56, and therefore,
Assuming that the incident angle of light incident on the optical system from its front side (angle with respect to the normal line of the reflective film 6) is θ, tan θ = 3.
Since 56/1 and θ≈74 °, 90 ° -of the light emitted from the outer surface of the prism sheet 3 to the reflective film 6 side.
An angle of about 74 ° = about 16 ° or more, that is, the reflection film 6
The light emitted at an angle larger than the range of about ± 16 ° with respect to the normal line is directly incident on the absorption wall 7 and absorbed, and the light emitted at the angle within the range of about ± 16 ° is reflected. Membrane 6
And is specularly reflected at the same reflection angle as the angle of incidence on the reflection film 6.

Of the light reflected by the reflection film 6, the light directed to the absorption wall 7 is incident on the absorption wall 7 and absorbed, and the light not incident on the absorption wall 7 is absorbed by the optical system. Emit to the front side.

The incident angle of the light reflected by the optical system and emitted to the front side corresponds to the position where the light is incident on the reflection film 6 between the plurality of absorption walls 7 (center of the cylindrical body). When it is a part to be
Although it is about 8 °, the light reflected by the reflection film 6 may be reflected by the absorption wall 7 depending on the incident position of the light on the reflection film 6.
Since most of the light reflected by the reflection film 6 is emitted to the front side of the optical system, the incident angle of the light is approximately 1 ° or less.

However, the incident angle of light of the optical system is about 1 °.
Hereinafter, for example, even if it is 0 °, a part of the incident light is incident on the plurality of absorption walls 7 from its end face and is absorbed, so that the light of the optical system is incident at an incident angle of 0 °. The reflectance of the incident light is about 90%.

FIG. 7 shows the relationship between the incident angle of light on the optical system composed of the reflection film 6 and the plurality of absorption walls 7 and the reflectance.

In this embodiment, since the plurality of light absorbing walls 7 are cylindrical bodies each having an inner peripheral surface serving as a light absorbing surface 7a, the optical system has a normal line to the reflecting film 6. The incident angle-reflectance characteristics shown in FIG. 7 are exhibited for light incident from any direction around the.

In the optical element 1, as described above, the optical layer 2 allows the light X of one polarization component of the two polarization components of the incident light, which are orthogonal to each other, to go straight through and transmit the light X. In order to refract and transmit the component light Y, focusing on the light incident from the direction along the normal line h1 of the optical layer 2, among the light, one of the light that has passed straight through the optical layer 2 and transmitted. The light X of the polarization component is transmitted to the plurality of light absorption walls 7
The light Y of the other polarization component, which is reflected by the reflection film 6 through the gap, travels straight through the optical layer 2 again, is emitted, and is refracted and transmitted through the optical layer 2, is absorbed by the light. Wall 7
Is incident on and absorbed.

Focusing on the light incident from a direction inclined with respect to the normal line h1 of the optical layer 2, among the light,
The light X of one polarization component that has passed straight through the optical layer 2 and has been transmitted.
Are incident on and absorbed by the light absorbing wall 7, and the optical layer 2
Of the light Y of the other polarization component that has been refracted and transmitted through, the light refracted in the direction along the normal line h1 is reflected by the reflection film 6 through the space between the plurality of light absorption walls 7, Light refracted in a direction inclined with respect to the normal line h1 enters the light absorption wall 7 and is absorbed.

That is, the optical element 1 receives the light incident from the direction along the normal line h1 of the optical layer 2 as follows:
The light X having one polarization component is reflected, and the light Y having the other polarization component is reflected.
Is absorbed, the light X of one polarization component is absorbed and the light Y of the other polarization component is absorbed with respect to light incident from a direction inclined with respect to the normal line h1 of the optical layer 2. It exhibits the property of reflecting a part of the light and absorbing the other light.

Therefore, the reflectance of light can be changed by controlling the incident directions of the light X of one polarization component and the light Y of the other polarization component which are incident on the optical element 1. By disposing the element 1 on the rear side of the polarization control element for controlling the polarization state of the transmitted light, the reflectance of the light incident from the front side of the polarization control element and incident on the optical element 1 is determined by the polarization control element. It is possible to perform reflective display which is changed by controlling the polarization state by.

Since the optical element 1 reflects both the light X of one polarization component and the light Y of the other polarization component, the optical element 1 has a light intensity higher than that of the one in which a reflection plate is arranged behind the polarizing plate. Therefore, a reflective display device having a bright display can be constructed.

In the optical element 1 of this embodiment, the optical layer 2 is composed of a prism sheet 3 in which a plurality of elongated prism portions 4 are densely arranged on one surface and are formed in parallel with each other, and the prism sheet 3 is formed. Has a refractive index greater than the refractive index,
Since the high refractive index layer 5 is provided on the one surface of the prism sheet 3 so as to cover the plurality of elongated prism portions 4, the elongated prism portion of the prism sheet 3 is included in the optical layer 2. 4, the light X of one polarization component (polarization component in the x direction) having a vibrating surface in a direction substantially orthogonal to the length direction of 4 is transmitted straight and transmitted, and vibrates in the length direction of the elongated prism portion 4. It is possible to have a function of refracting and transmitting the light Y of the other polarization component having the surface (polarization component in the y direction).

Further, in this embodiment, in the high refractive index layer 5 of the optical layer 2, the liquid crystal molecules have a molecular major axis in a direction substantially parallel to the lengthwise direction of the elongated prism portion 4 of the prism sheet 3. Since it is a liquid crystal polymer layer aligned and arranged,
The high refractive index layer 5 can be easily formed.

Further, in this embodiment, the light absorption wall 7 is
Is a tubular body having an inner surface as a light absorbing surface, and a plurality of the tubular light absorbing walls 7 are densely arranged in the surface direction of the reflecting film 6, so that the plurality of reflecting films 6 and Light incident on the optical system including the light absorbing wall 7 from any direction around the normal line of the reflective film 6 among the light transmitted through the optical layer 2 and incident on the optical system. Further, it is possible to have a function of reflecting light incident at an incident angle within a predetermined angle range from a direction along the normal line of the reflection film 6 and causing the light to enter the optical layer 2.

The light absorbing wall 7 is not limited to the cylindrical shape, but may be, for example, a polygonal cylindrical shape. Further, in the optical element 1 of the above-mentioned embodiment, the reflection film 6 is arranged on the outer surface side of the prism sheet 3 of the optical layer 2, and a plurality of absorption walls 7 are provided between the optical layer 2 and the reflection film 6. Although it is arranged,
Since the optical layer 2 exhibits the same characteristics with respect to the light incident from any of the surfaces thereof, the reflection film 6 is provided on the optical layer 2 in the same manner.
Is disposed on the outer surface side of the high refractive index layer (liquid crystal polymer layer) 5 of
A plurality of absorption walls 7 may be arranged between the optical layer 2 and the reflection film 6.

8 to 13 show an embodiment of the display device of the present invention using the optical element 1, and FIG. 8 is a partial sectional view of the display device.

The display device of this embodiment is as shown in FIG.
A polarization control element 10 for controlling the polarization state of transmitted light, an optical film 20 arranged on the front side which is the viewing side of the display of the polarization control element 10, and an optical element arranged on the rear side of the polarization control element 10. It consists of 1.

The polarization control element 10 is, for example, a liquid crystal element, and is disposed between the front substrate 11 which is the viewing side of the display and the rear substrate 12 which faces the front substrate 11. Electrodes 13 and 1 respectively provided on the inner surface
The liquid crystal layer 15 controls the polarization state of transmitted light according to the electric field applied between the four. Hereinafter, this polarization control element 10 will be referred to as a liquid crystal element.

The liquid crystal element 10 is, for example, of an active matrix type, and includes a pair of front and rear substrates 11,
Electrode 14 provided on the inner surface of rear substrate 12 of
Are a plurality of pixel electrodes arranged in a matrix in the row direction and the column direction, and electrodes 13 provided on the inner surface of the front substrate 11.
Is a single film-shaped counter electrode facing the plurality of pixel electrodes.

Although not shown in the drawing, on the inner surface of the rear substrate 12, a plurality of TFTs (thin film transistors) respectively connected to the plurality of pixel electrodes and a T of each row are provided.
A plurality of gate wirings for supplying gate signals to the FT and a plurality of data wirings for supplying data signals to the TFTs in each column are provided.

Then, the front substrate 11 and the rear substrate 12
Are bonded to each other via a frame-shaped sealing material (not shown) at the peripheral edge thereof, and the liquid crystal layer 15 is provided in a region surrounded by the sealing material between the substrates 11 and 12.

In addition, the liquid crystal element 10 of this embodiment is TN
The liquid crystal molecules of the liquid crystal layer 15 of the liquid crystal element 10 are of a (twisted nematic) type, and are formed by the alignment films 16 and 17 provided on the inner surfaces of the pair of substrates 11 and 12 so as to cover the electrodes 13 and 14. Each board 11, 12
The orientation direction in the vicinity of is regulated, and the twist orientation is substantially at a twist angle of 90 °.

As shown in FIGS. 1 to 7, the optical element 1 includes an optical layer 2 including a prism sheet 3 and a liquid crystal polymer layer (high refractive index layer) 5, and one surface of the optical layer 2. And a plurality of light absorbing walls 7 arranged substantially vertically between the optical layer 2 and the reflective film 6, and the optical layer 2 It is arranged on the rear side of the liquid crystal element 10 so as to face the liquid crystal element 10.

The optical film 20 has a prism sheet 21 in which a plurality of elongated prism portions 22 are densely arranged on one surface at a very small pitch of about 25 μm to 100 μm and formed in parallel with each other, and the prism sheet 21. And a high refractive index layer 23 provided on one surface of the prism sheet 21 so as to cover the plurality of elongated prism portions 22.

In this embodiment, the high refractive index layer 2
3 is formed thicker than the depth of the concave portions between the plurality of elongated prism portions 22 of the prism sheet 21 so that the outer surface thereof becomes a continuous flat surface.
3 may be formed in the recesses between the plurality of elongated prism portions 22 of the prism sheet 21 such that the outer surface of the high refractive index layer 23 is flush with the top of the elongated prism portions 22.

The prism sheet 21 is made of an optically isotropic transparent resin, for example, an acrylic resin having a refractive index of 1.511. The plurality of elongated prism portions 22 formed on one surface of the prism sheet 21 are Each has an isosceles triangular cross-sectional shape, and the inclination angles of the two inclined surfaces 22a and 22b are both 45 ° (see FIG. 9).

In the high refractive index layer 23, liquid crystal molecules are arranged with their long axes aligned in a direction substantially parallel to the length direction of the elongated prism portion 22 of the prism sheet 21.
The refractive index in the direction along the alignment direction of the liquid crystal molecules, that is, in the direction substantially parallel to the lengthwise direction of the elongated prism portion 22 of the prism sheet 21 is larger than the refractive index of the prism sheet 21, The prism sheet 2 has a refractive index in a direction substantially orthogonal to the orientation direction, that is, in a direction substantially orthogonal to the lengthwise direction of the elongated prism portion 22.
It consists of a liquid crystal polymer layer having a refractive index substantially equal to 1. Hereinafter, this high refractive index layer 23 is referred to as a liquid crystal polymer layer.

The refractive index of the liquid crystal polymer layer 23 in the direction substantially parallel to the lengthwise direction of the elongated prism portion 22 is 1.663, and the direction substantially orthogonal to the lengthwise direction of the elongated prism portion 22. Has a refractive index of 1.511.

That is, the optical film 20 has substantially the same structure as that of the optical layer 2 of the optical element 1, and, like the optical layer 2 of the optical element 1, two of the incident lights orthogonal to each other are provided. Of the polarized light components, one polarized light component having a vibrating surface in a direction substantially orthogonal to the lengthwise direction of the elongated prism portion 22, that is, the light of the polarized light component in the x direction is made to go straight and is transmitted therethrough. It has a characteristic of refracting and transmitting light of the other polarization component having a vibrating surface in a direction substantially parallel to the length direction of the portion 4, that is, light of the polarization component in the y direction.

FIG. 9 is a diagram showing a transmission path of light incident on the optical film 20 from a direction along its normal line (the normal line of the outer surface of the prism sheet 21 and the outer surface of the liquid crystal polymer layer 23) h2. Then, the prism sheet 21
Shows the path of light incident from the outer surface of.

As shown in FIG. 9, this optical film 2
0 represents the light X of the polarization component in the x direction out of the light incident at an incident angle of 0 ° parallel to the normal line h2 and the interface between the prism sheet 21 and the outside air (air) and the elongated prism. The interfaces between the inclined surfaces 22a and 22b of the portion 22 and the liquid crystal polymer layer 23 and the interface between the liquid crystal polymer layer 23 and the outside air are transmitted without refraction, and are parallel to the normal line h2 at an emission angle of 0 °. Emit in any direction.

Further, as described above, the inclination angles of the two inclined surfaces 22a and 22b of the elongated prism portion 22 are each 45 °, and the refractive index of the optically isotropic prism sheet 21 is 1. 511, since the refractive index of the liquid crystal polymer layer 23 in the direction substantially parallel to the longitudinal direction of the elongated prism portion 22 is 1.663, this optical film 20 is incident at the incident angle of 0 °. Of the light, the y
The light Y of the directional polarization component is refracted in the direction of 5.02 ° at the interface between the slanted surfaces 22a and 22b of the elongated prism portion 22 and the liquid crystal polymer layer 23, and is further exposed to the ambient air and the liquid crystal polymer layer 23. The light is refracted at the interface of and is emitted in the direction of 8.37 °.

One inclined surface 2 of the elongated prism portion 22
Light Y refracted at the interface between 2a and the liquid crystal polymer layer 23
The emission direction of the light Y refracted at the interface between the other inclined surface 22b and the liquid crystal polymer layer 5 is the normal line h.
2 are opposite directions with respect to each other. In the figure, if the leftward angle with respect to the normal line h2 is −, and the rightward angle is +, the elongated prism portion 22 has a −45 angle.
The light Y refracted at the interface between the inclined surface (the inclined surface on the left side in the drawing) 22a and the liquid crystal polymer layer 23 is +8.37 from the outer surface of the liquid crystal polymer layer 23 with respect to the normal h2.
The light Y emitted in the direction (right direction in the drawing) and refracted at the interface between the + 45 ° inclined surface (the right inclined surface in the drawing) 22b of the elongated prism portion 22 and the liquid crystal polymer layer 23 is A direction of −8.37 ° from the outer surface of the liquid crystal polymer layer 23 with respect to the normal line h2 (left direction in the drawing)
Emit to.

Although FIG. 9 shows a transmission path of light which is incident on the optical film 20 from a direction along the normal line h2, the optical film 20 is seen from a direction inclined with respect to the normal line h2. The transmission path of incident light is also the optical element 1
Is the same as that of the optical layer 2 of FIG.
The exit angle of the polarization component X in the x direction when the angle is 7 ° is +8.
The exit angle of the polarization component Y in the 37 ° and y directions is 0 ° and +19.
It is 09 °.

Further, the same characteristics are exhibited with respect to the light incident from the outer surface of the liquid crystal polymer layer 23, and in this case, the relationship between the incident angle and the exit angle is that the light is incident from the outer surface of the liquid crystal polymer layer 5. Is the same as when

The optical film 20 is arranged on the front side of the liquid crystal element 10 with one surface thereof, for example, the outer surface of the liquid crystal polymer layer 23 facing the liquid crystal element 10.

In the display device of this embodiment, dark display is performed when no electric field is applied between the electrodes 13 and 14 of the liquid crystal element 10, and bright display is performed when an electric field is applied between the electrodes 13 and 14. In the normally black mode, the optical film 20 has the prism sheet 2
1 in the length direction of the elongated prism portion 22 of the liquid crystal element 1
0 is arranged substantially parallel or orthogonal to the alignment direction of the liquid crystal molecules in the vicinity of the front substrate 11.
Are arranged such that the lengthwise direction of the elongated prism portion 4 of the prism sheet 3 of the optical layer 2 is substantially parallel to the lengthwise direction of the elongated prism portion 22 of the prism sheet 21 of the optical film 20.

This display device is a reflection type device that uses external light, which is the light of the environment in which it is used, for display. The image is displayed by being reflected by the optical element 1 arranged at.

In this display device, the front direction of the screen (the surface of the optical film 20 arranged in front of the liquid crystal element 10) (the direction near the normal line h2 of the optical film 20) is the most used environment. Used in the bright direction, the display is viewed from the front direction.

10 to 13 are schematic views showing the light transmission path of the display device, and FIGS. 10 and 11 show the case where no electric field is applied between the electrodes 13 and 14 of the liquid crystal element 10. FIG. 12 shows the paths of the light X of the polarization component in the x direction and the light Y of the polarization component in the y direction that are incident from the front direction.
13 shows that the liquid crystal molecules of the liquid crystal layer 15 are incident between the electrodes 13 and 14 of the liquid crystal element 10 from the front direction in a state in which an electric field is applied that vertically rises and aligns substantially perpendicularly to the surfaces of the substrates 11 and 12. The paths of light X having a polarization component in the x direction and light Y having a polarization component in the y direction are shown.

The light transmission path of the display device will be described by focusing on the light incident at an incident angle of 0 ° with respect to the normal line h2 of the optical film 20. Non-polarized light incident at an incident angle of ° (the ratio of the polarized light component X in the x direction to the light component Y in the y direction is 50
%), The light X of the polarization component in the x direction is
As shown in FIGS. 0 and 12, the light Y of the polarization component in the y direction travels straight through the optical film 20 and is incident on the liquid crystal element 10 as shown in FIGS.
The light is refracted by the optical film 20 and is + 8 ° with respect to the normal line h2 of the optical film 20. 37 and -8.37 °
The light is emitted in the direction of and enters the liquid crystal element 10.

The electrodes 13, 1 of the liquid crystal element 10 are
4 when no electric field is applied, that is, the liquid crystal layer 15
In the state where the liquid crystal molecules are twist-aligned at a twist angle of substantially 90 °, the light incident on the liquid crystal element 10 is substantially rotated by 90 ° in the process of passing through the liquid crystal layer 15, so that Of the light transmitted through the film 20 and incident on the liquid crystal element 10, the light X of the polarization component in the x direction.
However, the light Y of the polarization component in the y direction whose polarization state is substantially rotated by 90 ° is emitted to the rear side of the liquid crystal element 10, and the light Y of the polarization component in the y direction is substantially in the polarization state. 90
The X-polarized light component X in the x direction is emitted to the rear side of the liquid crystal element 10.

These lights are incident on the optical element 1 from its front surface, and among the lights, go straight through the optical film 20 as shown in FIG. The light Y having the polarization component of ## EQU1 ## which is incident on the optical element 1 is refracted by the optical layer 2 of the optical element 1, and is + 8.37 ° and −8 with respect to the normal line h1 of the optical layer 2.
8. The light is emitted in the direction of 37 ° and is incident on the optical system including the reflection film 6 and the plurality of absorption walls 7, and is incident on and absorbed by the plurality of absorption walls 7 either directly or by being reflected by the reflection film 6. It

Further, as shown in FIG. 11, the optical film 2
0 is refracted and transmitted to the + 8.37 ° and −8.37.
The light emitted in the direction of 0 °, transmitted through the liquid crystal element 10, becomes the light X of the polarization component in the x direction, and enters the optical element 1, travels straight through the optical layer 2 of the optical element 1 and is transmitted. The light enters the optical system at the incident angles of + 8.37 ° and 8.37 ° and is absorbed by the absorbing wall 7.

Therefore, the electrode 1 of the liquid crystal element 10 is
When no electric field is applied between 3 and 14, most of the lights X and Y of the polarization components in the x and y directions that are incident from the front side are absorbed by the absorption wall 7 of the optical element 1 and the display of that pixel is performed. Is a dark display with sufficient darkness.

On the other hand, the electrodes 13, 14 of the liquid crystal element 10 are
An electric field is applied between the liquid crystal molecules of the liquid crystal layer 15 to cause the substrate 11,
If the liquid crystal layer 15 is oriented so that it rises substantially perpendicularly to the 12th plane, the birefringence of the liquid crystal layer 15 is almost eliminated, so that the liquid crystal layer 15 is transmitted through the optical film 20.
The light X having the polarization component in the x direction and the light Y having the polarization component in the y direction are emitted to the rear side of the liquid crystal element 10 without changing the polarization state.

These lights are incident on the optical element 1 from the front surface thereof, and of the light, the light travels straight through the optical film 20 as shown in FIG. 12 and is transmitted to change the polarization state of the liquid crystal element 10. The light that has not been transmitted and is incident on the optical element 1 as the light X of the polarization component in the x-direction travels straight through the optical layer 2 of the optical element 1 and is transmitted to the reflection film at the incident angle of 0 °. 6 and a plurality of absorption walls 7 are incident on the optical system, and most of the light is reflected by the reflection film 6 and enters the optical layer 2 from the rear side.

In addition, as shown in FIG. 13, the optical film 20 is refracted and transmitted to the + 8.37 ° and −8.3.
Light emitted in the direction of 7 °, transmitted through the liquid crystal element 10 without changing the polarization state, and incident on the optical element 1 as the light Y of the polarization component in the y direction is the optical layer of the optical element 1. 2 is refracted and transmitted, and the direction of 0 ° with respect to the normal line h1 of the optical layer 2 or + 19.09 ° and −19.09.
The light exits in the direction of and enters the optical system.

Of the light, the light that has entered the optical element 1 at the incident angle of 0 ° is reflected by the reflective film 6 and enters the optical layer 2 from the rear side thereof, and the light of +19.0 is obtained.
Light incident on the optical element 1 at incident angles of 9 ° and −19.09 ° is incident on and absorbed by the plurality of absorption walls 7 either directly or by being reflected by the reflective film 6.

Of the light reflected by the reflection film 6 and incident on the optical layer 2 from the rear side at an incident angle of 0 °, most of the light X of the polarization component in the x direction is shown in FIG. As described above, the light travels straight through the optical layer 2 and further travels straight through the liquid crystal element 10 and the optical film 20, and is emitted in the front direction at an emission angle of 0 °.

Of the light reflected by the reflection film 6 and incident on the optical layer 2 from the rear side at an incident angle of 0 °, the light Y of the polarization component in the y direction is as shown in FIG. The optical layer 2 is refracted and transmitted to be −8.37 ° and +8.
The light exits in the direction of 37 °, passes through the liquid crystal element 10, and enters the optical film 20 from the rear surface.

As described above, the light incident on the optical film 20 from the rear surface at the incident angles of −8.37 ° and + 8.37 ° is refracted through the optical film 20 and transmitted,
The light is emitted to the front side with an emission angle of 0 ° and emission angles of + 19.09 ° and -19.09 ° with respect to the normal line h2 of the optical film 20.

Therefore, the electrode 1 of the liquid crystal element 10 is
When an electric field is applied between 3 and 14, the display of that pixel becomes a bright display.

Since the display of this display device is observed from the front as described above, the bright display is as shown in FIG.
2, the light X of the polarization component in the x direction emitted at an emission angle of 0 °, and the emission angle of 0 ° and + 19.09 ° as shown in FIG.
And the light Y of the polarized light component in the y direction emitted to the front side at the emission angle of −19.09 ° and the light emitted at the emission angle of 0 ° have sufficient brightness. .

That is, when an electric field is applied in which the liquid crystal molecules of the liquid crystal element 10 are substantially vertically raised and aligned, they are incident on the reflection film 6 of the optical element 1 at an incident angle of 0 ° and 0 °.
Of the light reflected in the X direction, the light X of the polarization component in the X direction
However, it goes straight through the optical layer 2 of the optical element 1 and is transmitted therethrough, and further goes straight through the liquid crystal element 10 and the optical film 20 to be transmitted and emitted in the front direction.

Therefore, a part of the incident light enters the absorption walls 7 of the optical element 1 from its end face and is absorbed, and the optical loss and the optical layer 2 and the optical element 1 of the optical element 1 are absorbed. Neglecting light loss in the process of passing through the film 20 and the liquid crystal element 10, when the electric field is applied, the light X of the polarization component in the x direction out of the light incident at an incident angle of 0 ° from the front side of the display device. , 100%, that is, the non-polarized light incident from the front side of the display device is emitted in the front direction at an emission rate of 50%.

Further, as described above, the optical layer 2 of the optical element 1 has about a part of the light Y of the polarization component in the y direction which is incident from the direction inclined by −8.37 ° with respect to the normal line h1. 5
4.4% of light is emitted at an emission angle of 0 °, and similarly, the optical film 20 also has a y-direction polarization component light Y incident from a direction inclined by −8.37 ° with respect to the normal h2. Out of
About 54.4% of light is emitted at an emission angle of 0 °.

Therefore, ignoring the above-mentioned optical loss,
When the electric field is applied, the light Y of the polarization component in the y direction out of the light incident at the incident angle of 0 ° from the front side of the display device is 54.
The emission rate of 4 × 54.4≈29.6%, that is, the emission rate of the unpolarized light incident from the front side of the display device is emitted in the front direction at about 14.8%.

Therefore, the electrode 1 of the liquid crystal element 10 is
The theoretical brightness of bright display observed from the front direction when an electric field is applied between 3 and 14 so as to orient the liquid crystal molecules so as to rise substantially perpendicularly to the surfaces of the substrates 11 and 12 (the above-mentioned light The value ignoring the loss is the light X of the polarization component in the x direction that is emitted in the front direction at an emission rate of 50% of the unpolarized light that is incident from the front side of the display device, and the unpolarized light that is incident from the front side of the display device. Of the light Y of the polarized light component in the y direction emitted in the front direction at an emission rate of about 14.8%, that is, about 64.8 of the intensity of the unpolarized light incident from the front side of the display device. Sufficient brightness with a strength of%.

[0117] Actually, a part of the incident light is absorbed by a plurality of absorption walls 7 of the optical element 1 from its end face and is absorbed, and a light loss of the optical element 1 is caused. Since there is light loss in the process of passing through the optical layer 2 and the optical film 20 and the liquid crystal element 10, the brightness of bright display observed from the front when the angle of incidence of light on the display device is 0 °. Becomes lower than the theoretical brightness.

However, the optical system including the reflection film 6 and the plurality of absorption walls 7 of the optical element 1 has a 0 ° angle as described above.
Since the light incident at the incident angle of is reflected in the 0 ° direction with a reflectance of about 90% (see FIG. 7), the light loss due to being absorbed by the absorption wall 7 is small, and the optical element is 1, the optical layer 2, the optical film 20, and the liquid crystal element 10.
The light loss in the process of passing through is extremely small.

Further, this display device, as described above,
The screen is used by directing the front direction of the screen to the brightest direction of the usage environment, and external light, which is the light of the usage environment, is incident not only from the front direction but also from various directions.

As can be seen by tracing the transmission path shown in FIG. 13 in reverse, the display device displays the light Y of the polarization component in the y direction which is incident from the front side at an incident angle of −19.09 °. Part of the light (horizontal prism 4 of optical element 1
Light incident on the inclined surface 4a of +45) and +1 from the front side.
Light Y of the polarization component in the y direction incident at an incident angle of 9.09 °
Part of the light (of the lateral prism portion 4 of the optical element 1
The light incident on the inclined surface 4a of 45) is reflected and emitted in the front direction, so that the emitted light raises the brightness of the bright display.

Therefore, the brightness of the bright display observed from the front direction is about 60% or more of the intensity of the non-polarized light incident from the front side of the display device.

As described above, in this display device, one of two polarization components of the incident light, which are orthogonal to each other, is provided on the front side, which is the display side of the display of the liquid crystal element 10 for controlling the polarization state of the transmitted light. An optical film 20 having a characteristic of allowing the component light to go straight through and transmitting the other polarization component light to be refracted and transmitted therethrough is provided on the rear side of the liquid crystal element 10, and two polarizations of incident light orthogonal to each other are provided. Among the components, an optical layer 2 having a characteristic of allowing light of one polarization component to go straight and to be transmitted and refracting and transmitting light of the other polarization component, and is arranged so as to face one surface of the optical layer 2. Reflective film 6
And a plurality of absorption walls 7 disposed between the optical layer 2 and the reflective film 6 at intervals in the surface direction of the reflective film 6 and substantially perpendicular to the reflective film 6. Since the optical element 1 is arranged with the optical layer 2 facing the liquid crystal element 10, a bright reflective display can be obtained.

In the display device of this embodiment, liquid crystal molecules are substantially formed between the liquid crystal element 10 between the front substrate 11 on the display observation side and the rear substrate 12 facing the front substrate 11. TN type liquid crystal element provided with a liquid crystal layer 15 twisted at a twist angle of 90 °, and the optical film 20 is provided on one surface with a plurality of elongated prism portions 22.
Prism sheet 2 in which are closely arranged and are parallel to each other
1 and a high refractive index layer 23 having a refractive index larger than that of the prism sheet 21 and provided on the one surface of the prism sheet 21 so as to cover the plurality of elongated prism portions 22. The optical layer 2 of the optical element 1
A prism sheet 3 in which a plurality of elongated prism portions 4 are densely arranged on one surface and formed in parallel with each other; and a prism sheet 3 having a refractive index larger than that of the prism sheet 3; And a high-refractive index layer (liquid crystal polymer layer) 5 provided on the surface of the optical film 2 so as to cover the plurality of elongated prism portions 4.
0 and the optical element 1 in the longitudinal direction of the elongated prism portion 22 of the prism sheet 21 of the optical film 20 and the longitudinal direction of the elongated prism portion 4 of the prism sheet 3 of the optical layer 2 of the optical element 1. Since they are arranged substantially parallel to each other, a dark display is sufficiently dark, a bright display is sufficiently bright, and a high-contrast display can be obtained.

In the optical film 20 and the optical element 1, the elongated prism portion 22 of the prism sheet 21 of the optical film 20 and the elongated prism of the prism sheet 3 of the optical layer 2 of the optical element 1 are arranged. The portion 4 may be disposed so as to be substantially orthogonal to the lengthwise direction, and by doing so, bright display is performed in the absence of an electric field when no electric field is applied between the electrodes 13 and 14 of the liquid crystal element 10. Element 10
In the state where an electric field is applied between the electrodes 13 and 14, the dark display normally white mode reflective display can be obtained.

Further, although the display device of the above embodiment is provided with the active matrix type liquid crystal element 10, the liquid crystal element 10 may be a simple matrix type liquid crystal element.

Further, although the liquid crystal element is used as the polarization control element 10 in the display device of the above-mentioned embodiment, the polarization control element 10 is not a liquid crystal element but any element that controls the polarization state of transmitted light. Good.

In addition, in the display device of the above-mentioned embodiment, the optical film 20 is provided with the high refractive index layer (liquid crystal polymer layer) thereof.
Although the outer surface of 23 is arranged so as to face the polarization control element (liquid crystal element) 10, the optical film 20 exhibits the same characteristics with respect to light incident from any of the surfaces. 20, the prism sheet 21
The outer surface may be arranged so as to face the polarization control element 10.

[0128]

According to the optical element of the present invention, of the two polarization components of the incident light which are orthogonal to each other, the light of one polarization component is made to go straight and transmitted, and the light of the other polarization component is made to be refracted and transmitted. An optical layer having characteristics, a reflective film disposed to face one surface of the optical layer, and the reflection between the optical layer and the reflective film with a space in the surface direction of the reflective film. Since it is composed of a plurality of light absorption walls arranged substantially perpendicular to the film, by arranging this optical element at the rear side of the polarization control element, a bright display type reflective display device is formed. can do.

In the optical element of the present invention, the optical layer has a prism sheet having a plurality of elongated prism portions densely arranged on one surface and formed in parallel with each other, and a refractive index larger than that of the prism sheet. It has preferably a high refractive index layer provided on one surface of the prism sheet to cover the plurality of elongated prism portions,
By doing so, in the optical layer, light of one polarization component along a direction substantially orthogonal to the length direction of the prism portion of the prism sheet is made to go straight and transmitted,
A function of refracting and transmitting the light of the other polarization component along the length direction of the elongated prism portion can be provided.

In this case, the high refractive index layer of the optical layer is composed of a liquid crystal polymer layer in which liquid crystal molecules are aligned with their long axes aligned substantially parallel to the length direction of the elongated prism portion of the prism sheet. It is more preferable that the high refractive index layer 5 can be easily formed.

Further, in this optical element, it is preferable that the light absorption wall is formed in a cylindrical shape, and a plurality of the cylindrical light absorption walls are arranged side by side in the surface direction of the reflection film. By the above, in the optical system composed of the reflection film and the plurality of absorption walls, the light incident from any direction around the normal line of the reflection film is transmitted through the optical layer and the optical It is possible to have a function of reflecting, of the light incident on the system, light incident at an incident angle within a predetermined angle range from the direction along the normal line of the reflective film and making the light incident on the optical layer.

Further, in the display device of the present invention, an optical film having the same characteristics as the optical layer of the above-mentioned optical element of the invention is provided on the front side, which is the display side, of the polarization control element for controlling the polarization state of the transmitted light. By arranging the optical element on the rear side of the polarization control element so that its optical layer faces the polarizing element, the light of one polarization component and the other polarization component incident on the optical element are arranged. Since the incident direction of the light is controlled by the optical film and the polarization control element to perform the reflective display in which the reflectance of the light by the optical element is changed, a bright reflective display can be obtained. .

In the display device of the present invention, the polarization control element has substantially 9 liquid crystal molecules between the front substrate which is the viewing side of the display and the rear substrate which faces the front substrate.
A liquid crystal element comprising a liquid crystal layer twist-aligned at a twist angle of 0 °, wherein the optical film includes a prism sheet in which a plurality of elongated prism portions are densely arranged on a rear surface and formed in parallel with each other, and the prism sheet. Of a high refractive index layer provided on the rear surface of the prism sheet to cover the plurality of elongated prism portions, the optical layer of the optical element is on the front surface. A prism sheet in which a plurality of elongated prism portions are closely arranged and formed in parallel with each other, and having a refractive index larger than that of the prism sheet, and provided on the front surface of the prism sheet so as to cover the plurality of elongated prism portions. The optical film and the optical element, the length of the elongated prism portion of the prism sheet of the optical film. And the lengthwise direction of the elongated prism portion of the prism sheet of the optical layer of the optical element is preferably substantially orthogonal or parallel to each other. By doing so, the dark display is sufficiently dark. In addition, a bright display is sufficiently bright and a high-contrast display can be obtained.

[Brief description of drawings]

FIG. 1 is a partial sectional view showing an embodiment of an optical element of the present invention.

FIG. 2 is a diagram showing a transmission path of light incident on the optical layer of the optical element in a direction along a normal line thereof.

FIG. 3 is a diagram showing a transmission path of light incident on the optical layer of the optical element in a direction inclined with respect to the normal line thereof.

FIG. 4 is a perspective view of a reflective film and a plurality of light absorbing walls of the optical element.

FIG. 5 is an enlarged perspective view of one light absorbing wall.

FIG. 6 is an enlarged cross-sectional view of the reflective film and a plurality of light absorbing walls.

FIG. 7 is a diagram showing a relationship between an incident angle of light and an reflectance of an optical system including the reflective film and a plurality of absorption walls.

FIG. 8 is a sectional view showing an embodiment of the display device of the present invention.

FIG. 9 is a diagram showing a transmission path of light incident on the optical film of the display device.

FIG. 10 is a schematic diagram showing a transmission path of light of one polarization component that is incident from the front direction when there is no electric field in the display device.

FIG. 11 is a schematic diagram showing a transmission path of light of the other polarization component which is incident from the front direction when there is no electric field in the display device.

FIG. 12 is a schematic diagram showing a transmission path of light of one polarization component incident from the front direction when an electric field is applied to the display device.

FIG. 13 is a schematic diagram showing a transmission path of light of the other polarization component incident from the front direction when an electric field is applied to the display device.

[Explanation of symbols]

1 ... Optical element 2 ... Optical layer 3 ... Prism sheet 4 ... Slender prism part 4a, 4b ... inclined surface 5 ... High refractive index layer (liquid crystal polymer layer) 6 ... Reflective film 7 ... Light absorbing wall 10 ... Polarization control element (liquid crystal element) 15 ... Liquid crystal layer 20 ... Optical film 21 ... Prism sheet 22 ... Slim prism 22a, 22b ... Inclined surface 23 ... High refractive index layer (liquid crystal polymer layer)

Claims (6)

[Claims] 1. An optical layer having characteristics that, of two polarization components of incident light, which are orthogonal to each other, light of one polarization component travels straight and is transmitted, and light of the other polarization component is refracted and transmitted. A reflection film disposed to face one surface of the optical layer, and between the optical layer and the reflection film, with a gap in the surface direction of the reflection film, substantially with respect to the reflection film. An optical element comprising a plurality of light absorbing walls arranged vertically. 2. The optical layer has a prism sheet in which a plurality of elongated prism portions are densely arranged on one surface and formed in parallel with each other, and a refractive index higher than that of the prism sheet. 2. The optical element according to claim 1, further comprising a high refractive index layer provided on the one surface of the high refractive index layer so as to cover the plurality of elongated prism portions. 3. The high refractive index layer of the optical layer comprises a liquid crystal polymer layer in which liquid crystal molecules are aligned with their long axes aligned in a direction substantially parallel to the length direction of the elongated prism portion of the prism sheet. The optical element according to claim 2, wherein: 4. The light absorbing wall comprises a cylindrical body having an inner surface as a light absorbing surface, and a plurality of the cylindrical light absorbing walls are arranged densely in the surface direction of the reflecting film. The optical element according to claim 1, wherein: 5. A polarization control element for controlling the polarization state of transmitted light, and of two polarized light components of incident light which are orthogonal to each other, one of the polarized light components is made to go straight and transmitted, and the other polarized light component is transmitted. An optical film having a characteristic of refracting and transmitting light, which is arranged on the front side which is the viewing side of the display of the polarization control element, and of one of the two polarization components of the incident light which are orthogonal to each other. An optical layer having a characteristic of directly advancing and transmitting the light of the other polarization component and refracting and transmitting the light of the other polarization component, a reflection film arranged to face one surface of the optical layer, the optical layer and the reflection. Between the film and a plurality of light absorbing walls arranged substantially perpendicular to the reflective film at intervals in the surface direction of the reflective film, the rear side of the polarization control element, the The optical layer is arranged to face the polarization control element. Display apparatus comprising: the academic element. 6. A polarization control element in which liquid crystal molecules are twist-aligned at a twist angle of substantially 90 ° between a front substrate which is a viewing side of a display and a rear substrate which faces the front substrate. A liquid crystal element provided with a layer, the optical film arranged on the front side of the liquid crystal element, a prism sheet in which a plurality of elongated prism portions are densely arranged in parallel on one surface, and the prism sheet And a high refractive index layer provided on the one surface of the prism sheet so as to cover the plurality of elongated prism portions, and is disposed on the rear side of the liquid crystal element. The optical layer of the optical element is
A prism sheet in which a plurality of elongated prism parts are densely arranged on one surface and formed in parallel with each other, and has a refractive index higher than the refractive index of the prism sheet, and the plurality of prism sheets are provided on the one surface of the prism sheet. It comprises a high refractive index layer provided to cover the elongated prism portion, the optical film and the optical element, the length direction of the elongated prism portion of the prism sheet of the optical film, and the optical layer of the optical element. 6. The display device according to claim 5, wherein the prism sheet is arranged so that the lengthwise direction of the elongated prism portion is substantially orthogonal or parallel.