JP2001083324A - Light reflecting element and scattering type liquid crystal display device using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a scattering type liquid crystal display device having sufficiently high brightness of light display and good contrast. SOLUTION: A 1st linearly polarizing plate 11, a phase plate 12 having an optical axis 12a in a thickness direction, a 2nd linearly polarizing plate 13 and a reflecting film 14 are successively laminated from the front face side to obtain the objective light reflecting element 10 having angle selective reflecting characteristics by which reflectance to light incident from the direction along a normal line of the phase plate 12 in light incident from the front face side, passing through the 1st linearly polarizing plate 11, the phase plate 12 and the 2nd linearly polarizing plate 13 and emergent to the front face side after reflection by the reflecting film 14 is lower than the reflectance to light incident from the direction at a tilt to the normal line. The light reflecting element 10 in disposed on the back face side of a scattering/transmission type liquid crystal element 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light reflecting element and a scattering type liquid crystal display using the same.

[0002]

2. Description of the Related Art As a liquid crystal display device, a pair of substrates each having electrodes provided on inner surfaces facing each other, and scattering of incident light according to an electric field applied between the pair of substrates, is performed between the pair of substrates. And a scattering type using a scattering / transmission type liquid crystal element comprising a liquid crystal layer for controlling transmission.

[0003] Conventionally, as this scattering type liquid crystal display device,
One in which a black light absorbing film is disposed on the back side of the scattering / transmission type liquid crystal element, and one in which a reflection film (specular reflection film or scattering reflection film) is disposed on the back side of the scattering / transmission type liquid crystal element. In addition, any of the scattering type liquid crystal display devices uses external light which is light of the use environment to control and display light by the liquid crystal layer of the scattering / transmission type liquid crystal element.

That is, in a scattering type liquid crystal display device in which a black light absorbing film is disposed on the back side of a scattering / transmission type liquid crystal element,
When an off-voltage is applied between the electrodes of the liquid crystal element, that is, when the liquid crystal molecules are aligned in an alignment state that scatters incident light, light incident on the liquid crystal element from the front is scattered by the liquid crystal layer, and the scattered light Among them, the light heading toward the front surface of the liquid crystal element (backscattered light) is emitted to the front of the liquid crystal element and observed, and the display in that area becomes a bright white display.

On the other hand, when an on-voltage of a voltage value is applied between the electrodes of the liquid crystal element so that the liquid crystal molecules are oriented so as to transmit the incident light with little scattering, the light incident on the liquid crystal element from the front is reduced. The light passes through the liquid crystal element with little scattering and is absorbed by the light absorbing layer, and the display in that region becomes black and dark.

Further, in a scattering type liquid crystal display device in which a reflection film is arranged on the back side of a scattering / transmission type liquid crystal element, when an off-voltage is applied between the electrodes of the liquid crystal element (the liquid crystal molecules are arranged so as to scatter incident light). (When aligned in a state), light incident on the liquid crystal element from the front is scattered by the liquid crystal layer, and of the scattered light, light directed toward the front surface of the liquid crystal element (backscattered light) is emitted forward of the liquid crystal element. In addition, light of the scattered light emitted to the back side of the liquid crystal element (forward scattered light)
Is reflected by the reflection film and is scattered again by the liquid crystal layer of the liquid crystal element, and of the scattered light, light directed toward the front surface of the liquid crystal element (forward scattered light of the scattered light) is emitted forward of the liquid crystal element. Back scattered light of the light directly incident on the liquid crystal layer and forward scattered light of the reflected scattered light are observed, and the display in that region becomes bright white.

On the other hand, when an on-voltage is applied between the electrodes of the liquid crystal element so that the liquid crystal molecules are aligned in an alignment state in which incident light is transmitted with little scattering, light incident on the liquid crystal element from the front is reduced. The light passes through the liquid crystal element without being scattered and is reflected by the reflection film, and the reflected light is transmitted again through the liquid crystal element, and most of the light is emitted out of the range of the visual field of the observer. The display becomes dark.

[0008]

However, in the conventional scattering type liquid crystal display device in which a black light absorbing film is disposed on the back side of the scattering / transmission type liquid crystal element, the dark display is a black display with sufficient darkness. However, since a bright display is displayed only with light emitted forward of light scattered by the liquid crystal layer of the liquid crystal element,
The brightness of the bright display is not enough and the screen is dark.

Further, in the conventional scattering type liquid crystal display device in which a reflection film is arranged on the back side of the scattering / transmission type liquid crystal element, the bright display emits light forward of light scattered by the liquid crystal layer of the liquid crystal element. And the light emitted to the back side of the liquid crystal element and reflected by the reflection film is displayed by the light, and thus a bright display with high luminance can be obtained. Among the light reflected by the reflective film and emitted forward, there is also light that exits within the range of the observer's field of view, so that the contrast ratio between the bright display and the dark display, that is, the contrast is poor.

The present invention provides a light-reflecting element which can be arranged on the back side of a scattering / transmission type liquid crystal element to constitute a scattering type liquid crystal display device having sufficient brightness of bright display and good contrast. It is another object of the present invention to provide a scattering type liquid crystal display device using the light reflecting element.

[0011]

The light reflecting element of the present invention comprises a first linear polarizing plate, a phase plate having an optical axis in a thickness direction, a second linear polarizing plate, and a reflecting film. The first linearly polarizing plate, the phase plate, and the second linearly polarizing plate are transmitted through the first linear polarizing plate, the phase plate, and the second linear polarizing plate, reflected by the reflection film, and emitted to the front side. Out of the light, the reflectivity for light incident from a direction along the normal to the phase plate has an angle selective reflection characteristic smaller than the reflectivity for light incident from a direction oblique to the normal. It is characterized by having.

In this light reflecting element, the reflectivity for light incident from a direction along the normal to the phase plate is smaller than the reflectivity for light incident from a direction oblique to the normal. Since it has selective reflection characteristics, it can be arranged on the back side of the scattering / transmission type liquid crystal element to form a scattering type liquid crystal display device with sufficient bright display and high contrast.

Further, the scattering type liquid crystal display device of the present invention comprises:
It comprises a pair of substrates provided with electrodes on inner surfaces facing each other, and a liquid crystal layer disposed between the pair of substrates and controlling scattering and transmission of incident light according to an electric field applied between the electrodes. A scattering / transmission type liquid crystal element; and a light reflection element disposed on the back side of the scattering / transmission type liquid crystal element, wherein the light reflection element has a first linear polarizing plate and an optical axis in a thickness direction. Having a phase plate, a second linear polarizer, and a reflective film are sequentially laminated from the front side, and are incident from the front side, and the first linear polarizer, the phase plate, and the second straight line Of the light transmitted through the polarizing plate and reflected by the reflective film and emitted to the front side, the reflectance for light incident from a direction along the normal to the phase plate is oblique to the normal. Select an angle smaller than the reflectance for light incident from an inclined direction And it is characterized in that it has a reflection characteristic.

That is, in this scattering type liquid crystal display device, the above-mentioned light reflecting element of the present invention is arranged on the back side of the scattering / transmission type liquid crystal element. A light that enters the liquid crystal element from the front and is emitted from the front of light scattered by the liquid crystal layer; and a light that exits to the back side of the liquid crystal element and is reflected by the light reflection element to form a liquid crystal display. Since light can be displayed again by light that is transmitted through the element again and scattered by the liquid crystal layer and is emitted forward, a bright display with sufficient brightness can be obtained.

Further, in this scattering type liquid crystal display device, the light reflection element has a reflectance with respect to light incident from a direction along a normal line of the phase plate from a direction obliquely inclined with respect to the normal line. Since it has an angle selective reflection characteristic smaller than the reflectance with respect to incident light, a dark display when the display is observed from the front direction which is a normal observation direction, that is, a direction near the normal to the screen of the liquid crystal element. Is a display having a sufficient light-dark ratio with respect to the bright display, and therefore has a good contrast.

According to another aspect of the present invention, there is provided a light-reflecting element comprising a linear polarizing plate, a phase plate having an optical axis in a thickness direction, and reflecting incident light having a predetermined polarization component and transmitting incident light having another polarization component. A selective reflection plate and a back film composed of a scattering reflection film or a light absorption film are sequentially laminated from the front side, and are incident from the front side, pass through the linear polarizing plate and the phase plate, and selectively reflect the light. The light reflected by the plate and emitted to the front side, or the light reflected by the selective reflection plate and emitted to the front side and transmitted through the selective reflection plate and scattered and reflected by the back film made of the scattering reflection film to form the front surface Among the light rubbing out to the side, the angle selection is such that the reflectance for light incident from a direction along the normal to the phase plate is smaller than the reflectance for light incident from a direction oblique to the normal. Must have reflective properties The one in which the features.

In this light reflecting element, the reflectance for light incident from a direction along the normal to the phase plate is smaller than the reflectance for light incident from a direction oblique to the normal. Since it has selective reflection characteristics, it can be arranged on the back side of the scattering / transmission type liquid crystal element to form a scattering type liquid crystal display device with sufficient bright display and high contrast.

According to another aspect of the invention, there is provided a scattering type liquid crystal display device comprising: a pair of substrates each having electrodes provided on inner surfaces facing each other; and an electric field applied between the pair of substrates. A scattering / transmission type liquid crystal element comprising a liquid crystal layer for controlling scattering and transmission of incident light according to the above, and a light reflection element arranged on the back side of the scattering / transmission type liquid crystal element. Has a linear polarizer, a phase plate having an optical axis in the thickness direction, a selective reflector that reflects incident light of a predetermined polarization component and transmits incident light of another polarization component, and a scattering reflection film or light absorption. A rear film made of a film is sequentially laminated from the front side, and is incident from the front side, transmitted through the linear polarizing plate and the phase plate, reflected by the selective reflection plate, and emitted to the front side. Or reflected by the selective reflector Out of the light emitted to the front side and transmitted through the selective reflection plate and scattered and reflected by the back film made of the scattering reflection film and emitted to the front side, incident from the direction along the normal line of the phase plate. The reflected light has an angle-selective reflection characteristic that is smaller than that of light incident from a direction oblique to the normal.

That is, this scattering type liquid crystal display device has the above-mentioned other light reflection element of the present invention arranged on the back side of the scattering / transmission type liquid crystal element. For example, a bright display, the light emitted from the front of the light scattered by the liquid crystal layer incident on the liquid crystal element from the front, and emitted to the back side of the liquid crystal element and reflected by the light reflecting element, Since light can be displayed by light that is transmitted again through the liquid crystal element and is emitted forward of light scattered by the liquid crystal layer, a bright display with sufficient brightness can be obtained. Can be obtained.

Further, in this scattering type liquid crystal display device, the light reflection element has a reflectance with respect to light incident from a direction along a normal line of the phase plate from a direction oblique to the normal line. Since it has an angle selective reflection characteristic smaller than the reflectance for incident light, the dark display when the display is observed from the front direction (the direction near the normal to the screen of the liquid crystal element), which is the normal observation direction, This is a display having a sufficient light-dark ratio with respect to the dark display, and thus the contrast is also good.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As described above, the light reflecting element of the present invention comprises a first linear polarizing plate, a phase plate having an optical axis in a thickness direction, a second linear polarizing plate, and a reflecting film. Are sequentially laminated from the front side, are incident from the front side, pass through the first linear polarizing plate, the phase plate, and the second linear polarizing plate, are reflected by the reflection film, and Out of the light emitted to the side, the reflectivity for light incident from a direction along the normal to the phase plate is smaller than the reflectivity for light incident from a direction oblique to the normal. Therefore, by arranging this light reflection element on the back side of the scattering / transmission type liquid crystal element, a scattering type liquid crystal display device with sufficient bright display and good contrast is provided. Can be configured.

In this light reflecting element, it is desirable that the transmission axis of the second linearly polarizing plate is arranged substantially orthogonal to the transmission axis of the first linearly polarizing plate. The dark display of the scattering type liquid crystal display device can be made substantially black.

As described above, the scattering type liquid crystal display device of the present invention comprises a first linear polarizing plate, a phase plate having an optical axis in the thickness direction, 2 linearly polarizing plates and a reflective film are sequentially laminated from the front side, and are incident from the front side and transmitted through the first linearly polarizing plate, the phase plate, and the second linearly polarizing plate. Out of the light reflected by the reflection film and emitted to the front side, the light incident from a direction in which the reflectance with respect to the light incident from a direction along the normal to the phase plate is oblique to the normal. A light reflection element having an angle-selective reflection characteristic smaller than the reflectance with respect to is provided, so that a bright display can be made sufficiently bright and good contrast can be obtained.

As described above, another light reflecting element according to the present invention includes a linear polarizing plate, a phase plate having an optical axis in a thickness direction, and a reflecting plate for reflecting incident light having a predetermined polarization component and forming another polarization component. A selective reflection plate that transmits incident light, and a back film made of a scattering reflection film or a light absorption film are sequentially laminated from the front side, and are incident from the front side and pass through the linear polarizer and the phase plate. The light reflected by the selective reflection plate and emitted to the front side, or the light reflected by the selective reflection plate and emitted to the front side and transmitted through the selective reflection plate and the back film made of the scattering reflection film Of the light scattered and reflected and emitted to the front side, the reflectance for light incident from a direction along the normal to the phase plate is the reflectance for light incident from a direction oblique to the normal. Angle-selective reflection characteristics smaller than Therefore, by arranging this light reflection element on the back side of the scattering / transmission type liquid crystal element, a scattering type liquid crystal display device with sufficient brightness of bright display and good contrast can be constituted. Can be.

In this light reflection element, the selective reflection plate has a reflection axis and a transmission axis in directions substantially orthogonal to each other, reflects incident light of a polarized component along the reflection axis, and extends along the transmission axis. Or a cholesteric liquid crystal that reflects light of one of the left and right circularly polarized light components and transmits other polarized light components. Those consisting of layers are preferred.

When the selective reflection plate is the polarization reflection plate, it is desirable that the polarization reflection plate is arranged so that its transmission axis is substantially parallel to the transmission axis of the linear polarization plate. The difference between the reflectance for light incident from a direction along the normal line of the phase plate and the reflectance for light incident from a direction oblique to the normal line is increased, and scattering with better contrast is achieved. Type liquid crystal display device.

In the case where the selective reflection plate is made of the cholesteric liquid crystal layer, it is preferable that the reflection wavelength band is a band covering almost the entire visible light band. The bright display and the dark display can be displayed without banding.

As described above, another scattering type liquid crystal display device of the present invention comprises a linear polarizing plate, a phase plate having an optical axis in a thickness direction, and a predetermined plate on the back side of the scattering / transmission type liquid crystal element. A selective reflection plate that reflects the incident light of the polarized light component and transmits the incident light of the other polarized light component, and a back film made of a scattering reflection film or a light absorbing film are sequentially stacked from the front side, and are incident from the front side. And light transmitted through the linear polarizing plate and the phase plate, reflected by the selective reflection plate, and emitted to the front side,
Alternatively, of the light reflected by the selective reflection plate and emitted to the front side and the light transmitted through the selective reflection plate and scattered and reflected by the back film made of the scattering reflection film and emitted to the front side, the phase plate A light reflection element having an angle selective reflection characteristic in which the reflectance for light incident from a direction along the normal line is smaller than the reflectance for light incident from a direction oblique to the normal line. Yes, so that bright display can be made sufficiently bright and good contrast can be obtained.

In this scattering type liquid crystal display device, if the back film of the light reflection element is a scattering reflection film, the light enters the scattering / transmission type liquid crystal element from the front, emits to the back side of the liquid crystal element, and emits light. Of the light incident on the light reflection element from the front side, the light reflected by the selective reflection plate through the linear polarizing plate and the phase plate and the light reflected by the selective reflection plate and transmitted through the selective reflection plate by the scattering reflection film. Since both the scattered and reflected light is emitted to the front side of the light reflecting element, more reflected light can be made incident on the liquid crystal element from the back side to increase the screen brightness.

In this scattering type liquid crystal display device,
If the back film of the light reflecting element is a light absorbing film, light incident on the scattering / transmission type liquid crystal element from the front, emitted to the back side of the liquid crystal element, and incident on the light reflecting element from the front side thereof. The light transmitted through the linear polarizer and the phase plate and reflected by the selective reflection plate is emitted to the front side of the light reflection element and is incident on the liquid crystal element from the back side, and the selection is performed. Since the light transmitted through the reflection plate is absorbed by the light absorbing film, a dark display can be made close to black, and good contrast can be obtained.

[0031]

FIG. 1 is an exploded perspective view of a scattering type liquid crystal display device according to a first embodiment of the present invention.
(A) shows a light transmission path when the liquid crystal molecules 8a of the scattering / transmission type liquid crystal element 1 are aligned in an alignment state that scatters incident light, and (b) shows that the liquid crystal molecules 8a of the liquid crystal element 1 FIG. 3 shows a light transmission path when the light is oriented in an orientation state in which incident light is transmitted with little scattering.

This scattering type liquid crystal display device comprises a scattering / transmission type liquid crystal element 1 for scattering and transmitting incident light, and a light reflecting element 10 arranged on the back side of the liquid crystal element 1.

FIG. 2 is a cross-sectional view of a part of the scattering / transmission type liquid crystal element 1. This liquid crystal element 1 has a pair of transparent substrates 2, 3 having transparent electrodes 4, 5 provided on inner surfaces facing each other. And a liquid crystal layer 6 disposed between the pair of substrates 2 and 3 and controlling scattering and transmission of incident light in accordance with an electric field applied between the electrodes 4 and 5.

The pair of substrates 2 and 3 are joined at their peripheral edges via a frame-shaped sealing material (not shown), and the liquid crystal layer 6 is provided between the substrates 2 and 3 by the sealing material. It is provided in a region surrounded by.

The scattering / transmission type liquid crystal element 1 used in this embodiment is of a polymer dispersion type, and its liquid crystal layer 6 has a liquid crystal / liquid crystal type.
It is a polymer composite layer. This liquid crystal / polymer composite layer comprises a nematic liquid crystal 8 having a positive dielectric anisotropy in a transparent polymer layer 7.
And a liquid crystal 8 is confined in each gap of the polymer layer 7 polymerized so as to have a cross section like a sponge.

The liquid crystal element 1 is of an active matrix type, and an electrode 5 provided on the inner surface of one substrate (the lower substrate in FIG. 2) 3 has a plurality of pixels arranged in a matrix. The electrode and the electrode 4 provided on the inner surface of the other substrate 21 are a single-film counter electrode facing all of the plurality of pixel electrodes 5.

Although not shown in FIG. 2, a plurality of TFTs (thin film transistors) connected to the plurality of pixel electrodes 5 are provided on the inner surface of the substrate 3 on which the pixel electrodes 5 are provided. A plurality of gate wirings and data wirings for supplying a gate signal and a data signal to the TFT are provided.

Next, the light reflection element 10 disposed on the back side of the scattering / transmission type liquid crystal element 1 will be described. The light reflection element 10 used in this embodiment is, as shown in FIG. A linear polarizing plate 11, a phase plate having an optical axis 12a in the thickness direction (hereinafter referred to as a vertical axis phase plate) 12, a second linear polarizing plate 13, and a reflection film (specular reflection film or scattering reflection film) 14 Are sequentially laminated from the front side.

The first linearly polarizing plate 11 is disposed so that its transmission axis 11a is oriented in an arbitrary direction.
Of the first linearly polarizing plate 11 is arranged substantially orthogonal to the transmission axis 11a of the first linearly polarizing plate 11.

The longitudinal axis phase plate 12 is a phase plate laminate in which two uniaxial phase plates having optical axes in a direction along a plane direction are laminated with their optical axes substantially orthogonal to each other. Alternatively, the vertical phase plate 12 is made of a polymer liquid crystal film obtained by polymerizing a polymer liquid crystal in a state in which the liquid crystal molecules are vertically aligned. 12a.

Since the vertical axis phase plate 12 has the optical axis 12a in the direction along the normal line, it has no phase difference with respect to the incident light from the direction along the normal line. Has a phase difference with respect to incident light from a direction obliquely inclined with respect to the normal.

The longitudinal axis phase plate 12 preferably has an optical axis 12a substantially parallel to the normal line.
The optical axis 12a may be slightly inclined with respect to the normal line. When the optical axis 12a of the vertical phase plate 12 is inclined with respect to the normal line, The direction of inclination of the optical axis 12a is changed to the transmission axis 11 of one of the first and second linear polarizers 11 and 13.
a or 13a may be arranged in a direction substantially parallel to or close to 13a.

The light reflecting element 10 enters from the front side, passes through the first linear polarizing plate 11, the longitudinal phase plate 12, and the second linear polarizing plate 13 and is reflected by the reflecting film 14. The emitted light is emitted to the front side.

That is, the light incident on the light reflecting element 10 from the front side is first converted by the first linear polarizing plate 11 into a polarization component along a direction (absorption axis) orthogonal to the transmission axis 11a. The light is absorbed, becomes linearly polarized light along the transmission axis 11a of the first linearly polarizing plate 11, and is incident on the longitudinal axis phase plate 12.

This vertical phase plate 12 has an optical axis 12a in a direction along the normal line, and does not have a phase difference with respect to incident light from the direction along the normal line. Since there is a phase difference with respect to incident light from a direction obliquely inclined with respect to the normal line, of the linearly polarized light transmitted through the first linearly polarizing plate 11 and incident on the vertical axis phase plate 12, Light incident on the longitudinal axis phase plate 12 from the direction along the normal line passes through the longitudinal axis phase plate 12 without generating a phase difference, that is, without substantially changing the polarization state, and Light incident on the second linear polarizing plate 13 as it is and incident from a direction obliquely inclined with respect to the normal line generates a phase difference in the process of transmitting through the vertical axis phase plate 12 and becomes elliptically polarized light. , And enters the second linear polarizing plate 13.

As described above, the second linearly polarizing plate 13 is disposed so that its transmission axis 13a is substantially orthogonal to the transmission axis 11a of the first linearly polarizing plate 11, so that the vertical Light incident on the axial phase plate 12 from the direction along the normal line, transmitted through the vertical phase plate 12 with almost no change in the polarization state, and incident on the second linear polarizer 13, ie, the first light Most of the linearly polarized light along the transmission axis 11a of the linearly polarizing plate 11 is absorbed by the second linearly polarizing plate 13.

On the other hand, light (linearly polarized light along the transmission axis 11a of the first linearly polarizing plate 11) incident on the vertical phase plate 12 from a direction oblique to its normal line Since the elliptically polarized light is transmitted through the axial phase plate 12 as elliptically polarized light and is incident on the second linearly polarizing plate 13, the elliptically polarized light is orthogonal to the transmission axis 13 a of the second linearly polarizing plate 13. The light of the polarization component along the direction (absorption axis) is absorbed by the second linear polarizer 13, but the light of the polarization component along the transmission axis 13 a of the second linear polarizer 13 is The light passes through the second linear polarizing plate 13 and enters the reflection film 14, and is reflected by the reflection film 14.

The light reflected by the reflection film 14 passes through the second linear polarizing plate 13 again and is incident on the vertical phase plate 12 from the back side thereof, and becomes elliptically polarized light to become the elliptically polarized light. Light is emitted to the front side of the phase plate 12.

That is, the light incident on the reflection film 14 is
In the above-mentioned incident path from the front side, the second linearly polarizing plate out of the light that has entered the longitudinal axis phase plate 12 from a direction obliquely inclined with respect to its normal line and has become elliptically polarized light. 13 is light transmitted through the reflective film 1
The light (linearly polarized light) reflected by 4 and transmitted again through the second linear polarizing plate 13 is incident on the longitudinal axis phase plate 12 from a direction obliquely inclined with respect to its normal line. In the process of transmitting through the phase plate 12, a phase difference is generated again, and the light becomes elliptically polarized light.

The elliptically polarized light emitted to the front side of the longitudinal phase plate 12 is incident on the first linearly polarized light plate 11 from the back side, and the first linearly polarized light of the elliptically polarized light is The light of the polarization component along the direction (absorption axis) orthogonal to the transmission axis 11a of the plate 11
The light of the polarization component absorbed by the first linear polarizing plate 11 and along the transmission axis 11a of the first linear polarizing plate 11 is transmitted through the first linear polarizing plate 11 and emitted to the front side as reflected light by the light reflecting element 10. I do.

As described above, the light reflecting element 10 converts the light incident from the front side of the light reflecting element 10 from the direction along the normal of the longitudinal axis phase plate 12 to the second linear polarizing plate 13.
Of the light incident from the direction oblique to the normal to the vertical axis phase plate 12, the light incident on the reflective film 14 through the above-described path is reflected by the reflective film 14 and Therefore, the light reflecting element 10 has a reflectance with respect to light incident from a direction along a normal line of the vertical axis phase plate 12 in a direction obliquely inclined with respect to the normal line. It has an angle-selective reflection characteristic smaller than the reflectance with respect to light incident from the light source.

Therefore, by arranging the light reflecting element 10 on the back side of the scattering / transmission type liquid crystal element 1, a scattering type liquid crystal display device having sufficient brightness of bright display and good contrast can be constituted. .

The light reflecting element 10 used in this embodiment
Represents the second linear polarizing plate 13 and its transmission axis 13a
Are arranged substantially orthogonal to the transmission axis 11a of the linear polarizing plate 11, and are incident on the vertical phase plate 12 from a direction along the normal line, and change the polarization state of the vertical phase plate 12. Most of the light that has passed through and entered the second linear polarizing plate 13 (linearly polarized light along the transmission axis of the first linear polarizing plate 11) is absorbed by the second linear polarizing plate 13. The reflectance with respect to the light incident from the direction along the normal line of the vertical axis phase plate 12 is substantially 0, so that the dark display of the scattering type liquid crystal display device can be made substantially black.

The scattering type liquid crystal display device of this embodiment uses external light which is the light of the use environment to control and display the light scattering by the liquid crystal layer 6 of the scattering / transmission type liquid crystal element 1. When an off-voltage is applied between the electrodes 4 and 5 of the liquid crystal element 1 so that the liquid crystal molecules 8a of the liquid crystal layer 6 are oriented in a random direction, the display of the pixel area becomes bright. When an on-voltage is applied between the electrodes 4 and 5 so that the liquid crystal molecules 8a are oriented substantially perpendicular to the surfaces of the substrates 2 and 3, the display of the pixel region becomes dark.

That is, when an off-voltage is applied between the electrodes 4 and 5 of the scattering / transmission type liquid crystal element 1 so that the liquid crystal molecules 8a of the liquid crystal layer 6 are oriented in a random direction. When the liquid crystal element 8a is oriented so as to scatter incident light, light incident on the liquid crystal element 1 from the front is transmitted through the liquid crystal layer as shown by an arrow in FIG. The light scattered by the light 6 and directed toward the front surface of the liquid crystal element 1 (backscattered light) out of the scattered light is emitted forward of the display element 1.

Also, of the light scattered by the liquid crystal layer 6, the light (forward scattered light) heading toward the back surface of the liquid crystal element 1 is
The light is emitted to the back side of the liquid crystal element 1 and the light reflecting element 10
From the front side.

At this time, light emitted to the back side of the liquid crystal element 1 is scattered light (forward scattered light), and most of the light is applied to the light reflecting element 10 by the method of the vertical phase plate 12. Light enters from a direction oblique to the line.

For this reason, most of the light that has entered the light reflecting element 10 from the front side and transmitted through the first linear polarizing plate 11 to become linearly polarized light, The light transmitted through the second linear polarization plate 13 is incident on the second linear polarization plate 13, and the light transmitted through the second linear polarization plate 13 is reflected by the reflection film 14, and the reflected light is converted into the second linear polarization light. Plate 13, longitudinal phase plate 12, and first linear polarizer 11
And is emitted to the front side of the light reflecting element 10.

The reflected light emitted to the front side of the light reflecting element 10 re-enters the liquid crystal element 1 from the back side and is scattered by the liquid crystal layer 6. Light directed toward the front surface (forward scattered light) is emitted forward.

Therefore, according to this scattering type liquid crystal display device, a bright display is incident on the liquid crystal element 1 from the front and the liquid crystal layer 6
The light (backscattered light) of the light scattered by the light emitted in front of the liquid crystal element 1 and emitted to the back side of the liquid crystal element 1 and reflected by the light reflecting element 10, and It can be displayed by light emitted forward (forward scattered light) of the light transmitted and scattered by the liquid crystal layer 6, and therefore, the light absorbing film is disposed on the back side of the scattering / transmission type liquid crystal element. Sufficient and sufficient brightness compared to a conventional scattering type liquid crystal display device (a device that displays a bright display only with light that enters the liquid crystal element from the front and is scattered by the liquid crystal layer and is emitted forward). A bright display of brightness can be obtained.

This bright display is a white display without banding, and the light emitted forward is scattered light having a substantially uniform intensity distribution scattered by the liquid crystal layer 6 of the liquid crystal element 1. The display brightness when viewed from the front direction, which is the normal viewing direction, that is, the direction near the normal line of the screen of the liquid crystal element 1, is sufficient.

An ON voltage was applied between the electrodes 4 and 5 of the scattering / transmission type liquid crystal element 1 so that the liquid crystal molecules 8a of the liquid crystal layer 6 were oriented almost perpendicular to the surfaces of the substrates 2 and 3. In other words, when the liquid crystal molecules 8a are aligned in an alignment state in which the incident light is transmitted with little scattering, the light transmission path at that time is indicated from the front as shown by the arrow in FIG. The light that has entered the liquid crystal element 1 transmits through the liquid crystal layer 6 with almost no scattering, exits to the rear side of the liquid crystal element 1, and enters the light reflection element 10 from the front side.

Although FIG. 1 shows only the path of light incident from the direction along the normal line of the screen of the liquid crystal element 1, external light enters the liquid crystal element 1 at various incident angles. When the liquid crystal molecules 8a are oriented so as to transmit incident light with little scattering, incident light from the front exits to the back side of the liquid crystal element 1 at various exit angles corresponding to the incident angles. Are incident on the light reflecting element 10 at various incident angles.

The light transmitted through the liquid crystal element 1 and incident on the light reflecting element 10 from the front side thereof is transmitted through the first linear polarizing plate 11 to become linearly polarized light and incident on the vertical phase plate 12. I do.

Then, of the linearly polarized light incident on the vertical axis phase plate 12, the light incident from the direction along the normal line of the vertical axis phase plate 12 is reflected on the vertical axis phase plate 12 without substantially changing the polarization state. The light passes through the plate 12 and is absorbed by the second linear polarizing plate 13 disposed so that the transmission axis 13a is substantially perpendicular to the transmission axis 11a of the first linear polarizing plate 11.

The linearly polarized light (not shown) incident on the vertical axis phase plate 12 from a direction obliquely inclined with respect to the normal thereof becomes elliptically polarized light as described above, and The second linear polarizer 1 of the elliptically polarized light is transmitted through the plate 12 and is incident on the second linear polarizer 13.
The light of the polarization component along the direction (absorption axis) orthogonal to the third transmission axis 13a is absorbed by the second linear polarizer 13.

As described above, in the pixel region in which the liquid crystal molecules 8a of the liquid crystal layer 6 of the liquid crystal element 1 are oriented so as to transmit the incident light with little scattering, the light is incident from the front at various incident angles. The light transmitted through the liquid crystal element 1 and incident on the light reflecting element 10 is incident from the direction along the normal line of the vertical axis phase plate 12, and the second linearly polarizing plate 13 is hardly changed in polarization state. And the light incident on the second linearly polarizing plate 13 as an elliptically polarized light as an elliptically polarized light. Transmission axis 13a of the linear polarizing plate 13
The light of the polarization component along the direction (absorption axis) orthogonal to the above is absorbed by the second linear polarizing plate 13, and the display of the pixel area becomes dark.

However, in this case, the light reflecting element 10
Is incident from a direction obliquely inclined with respect to the normal line of the longitudinal axis phase plate 12, becomes elliptically polarized light, and becomes the second linear polarizing plate 13.
The light of the polarization component along the transmission axis 13a of the second linear polarizing plate 13 of the light incident on the second linear polarizing plate 13 is transmitted through the second linear polarizing plate 13 and reflected by the reflection film 14, and the reflected light Are transmitted through the second linear polarizer 13, the vertical phase plate 12, and the first linear polarizer 11, and are emitted to the front side of the light reflecting element 10.

The reflected light emitted to the front side of the light reflecting element 10 re-enters the liquid crystal element 1 from the rear side, passes through the liquid crystal element 1 and is emitted forward, so that the light is , Resulting in light leakage from the dark display area.

However, the reflected light from the light reflecting element 10 at this time is the light of the light absorbed by the second linear polarizer 13 of the light incident on the light reflecting element 10 at various incident angles. The light is extremely small compared to the amount, and the intensity of light emitted in the front direction is sufficiently low.

That is, for example, when the reflection film 14 on the back surface of the light reflection element 10 is a mirror reflection film, the reflection film 14 reflects the incident light at the same reflection angle as the incident angle. 14 is incident on the light reflecting element 1.
0, which is incident obliquely, transmitted through the vertical linear phase plate 12 as elliptically polarized light, and transmitted through the second linear polarizer 13 out of the light incident on the second linear polarizer 13 Since the light is incident on the reflection film 14 in a direction obliquely inclined with respect to the normal line, the light is reflected by the reflection film (specular reflection film) 14 in a direction obliquely inclined with respect to the normal line. Is reflected.

For this reason, the leakage light emitted to the front side of the light reflecting element 10 and transmitted through the liquid crystal element 1 and emitted forward on the observation surface side has the intensity of the light emitted in the front direction.
The light has an intensity distribution lower than the intensity of light emitted in a direction oblique to the front direction.

When the reflection film 14 on the back surface of the light reflection element 10 is a scattering reflection film, light (linearly polarized light) transmitted through the second linear polarizing plate 13 and incident on the reflection film 14 Is scattered and reflected by the reflection film (scattering / reflection film) 14 to produce light whose polarization state is disturbed, and the reflected light is orthogonal to the transmission axis 13a of the second linear polarizer 13. The light of the polarization component along the direction (absorption axis) is absorbed by the second linear polarizing plate 13, and the light of the polarization component along the transmission axis 13 a of the second linear polarizing plate 13 is
The light passes through the second linear polarizing plate 13 and further passes through the vertical axis phase plate 12 and the first linear polarizing plate 11 and is emitted to the front side of the light reflecting element 10.

For this reason, when the reflection film 14 is a scattering reflection film, the leaked light emitted to the front side of the light reflecting element 10 and transmitted through the liquid crystal element 1 and emitted forward is the second light. The second linear polarizer of the reflected light whose polarization state has been disturbed by the scattered reflection on the reflective film 14 compared to the intensity of the light transmitted through the linear polarizer 13 and incident on the reflective film 14 The light whose intensity has been reduced by the amount of light absorbed by the light 13, and thus the light emitted in the front direction has sufficiently low intensity.

Therefore, the dark display when the display is observed from the front direction, which is the normal observation direction, is a display having a sufficient contrast ratio with respect to the bright display. For example, as described above, the bright display can be made sufficiently bright, and the dark display can be made sufficiently dark, so that good contrast can be obtained.

Further, in the scattering type liquid crystal display device of this embodiment, the light reflecting element 10 is connected to the second linear polarizing plate 13 by the transmission axis 13a and the transmission axis 11a of the first linear polarizing plate 11 to the transmission axis 11a.
Since the light reflecting element 10 has a configuration in which the light is incident substantially perpendicularly to the vertical axis of the phase plate 12, the reflectance of the light reflecting element 10 is substantially zero as described above. Therefore, the dark display can be made substantially black.

The transmission axis 11a of the first linear polarizer 11 and the second linear polarizer 13
Is not limited to substantially 90 degrees, but is not limited to about 90 degrees.
An angle range of more than 5 degrees and 90 degrees or less (preferably 6 degrees)
0 degree to 90 degree angle range, more preferably 75 degree to 9 degree
0 degree angle range), and the first linear polarizer 11
If the crossing angle between the transmission axis 11a and the transmission axis 13a of the second linear polarizing plate 13 is within this range, the angle-selective reflection characteristic of the light reflecting element 10 is changed from the direction along the normal to the vertical axis phase plate 12 The characteristic is that the reflectance with respect to the reflected light is smaller than the reflectance with respect to the light incident from the direction oblique to the normal line, and a scattering type liquid crystal display device having sufficient brightness of bright display and good contrast is provided. be able to.

[Second Embodiment] FIG. 3 is an exploded perspective view of a scattering type liquid crystal display device showing a second embodiment of the present invention.
(A) shows a light transmission path when the liquid crystal molecules 8a of the scattering / transmission type liquid crystal element 1 are aligned in an alignment state that scatters incident light, and (b) shows that the liquid crystal molecules 8a of the liquid crystal element 1 FIG. 3 shows a light transmission path when the light is oriented in an orientation state in which incident light is transmitted with little scattering.

The scattering type liquid crystal display device of this embodiment has a linear polarizing plate 21 on the back side of the scattering / transmission type liquid crystal element 1 for scattering and transmitting incident light, and a vertical axis having an optical axis 22a in the thickness direction. Phase plate 22 and selective reflection plate 23 that reflects incident light of a predetermined polarization component and transmits incident light of another polarization component
And a back reflection film 24 (hereinafter, referred to as a scattering reflection film) made of a scattering reflection film, in which a light reflection element 20 having a configuration in which the light reflection element 20 is sequentially stacked from the front surface side is disposed. The scattering / transmission type liquid crystal element 1 is of the same polymer dispersion type as that used in the first embodiment.

In the light reflecting element 20 of this embodiment, the vertical axis phase plate 22 is oriented in the direction along the normal line similarly to the vertical axis phase plate 12 of the light reflecting element 10 of the first embodiment. Has an optical axis 22a, does not have a phase difference with respect to incident light from a direction along the normal line, and has a phase difference with respect to incident light from a direction oblique to the normal line. It has.

The longitudinal axis phase plate 22 preferably has an optical axis 22a substantially parallel to the normal.
The optical axis 22a may be slightly inclined with respect to the normal line. When the optical axis 22a of the vertical phase plate 22 is inclined with respect to the normal line, the vertical axis It is only necessary to dispose the optical axis 22 in such a manner that the inclination direction of the optical axis 22a is directed substantially parallel to or close to the transmission axis 21a of the linear polarizing plate 21.

In the light reflection element 20 of this embodiment, the selective reflection plate 23 is a polarization reflection plate, and a selective reflection plate made of this polarization reflection plate (hereinafter, referred to as a polarization reflection plate).
23 has a reflection axis 23s and a transmission axis 23p in directions substantially orthogonal to each other, reflects incident light of a polarization component along the reflection axis 23s, and transmits incident light of a polarization component along the transmission axis 23p. Selective reflection characteristics. The polarization reflection plate 23 has characteristics in which the reflection characteristic and the transmission characteristic have no wavelength dependence, and reflects incident light at a reflection angle substantially equal to the incident angle, such as specular reflection.

The polarization reflection plate 23 has its transmission axis 23p substantially parallel to the transmission axis 21a of the linear polarization plate 21 and its reflection axis 23s set to the transmission axis 2 of the linear polarization plate 21.
1a is arranged substantially orthogonally.

The light reflecting element 20 receives light incident from the front side thereof, passes through the linear polarizing plate 21, the longitudinal axis phase plate 22, and the polarizing reflecting plate 23 and reflects the light reflected by the scattering reflection film 24 on the front side. Out.

That is, the light incident on the light reflection element 20 from the front side is first absorbed by the linear polarizing plate 21 into the light of the polarization component along the direction (absorption axis) orthogonal to the transmission axis 21a. Then, the light is converted into linearly polarized light along the transmission axis 21a of the linearly polarizing plate 21 and is incident on the vertical axis phase plate 22.

Of the linearly polarized light incident on the vertical phase plate 22, the light incident on the vertical phase plate 22 from the direction along the normal thereof changes the polarization state of the vertical phase plate 22 almost. The linearly polarized light is transmitted without being incident on the polarizing reflection plate 23 as it is, and the light incident from the direction obliquely inclined with respect to the normal line has a phase difference in the process of transmitting through the vertical axis phase plate 22. Then, the light is converted into elliptically polarized light and enters the polarization reflector 23.

As described above, the polarization reflection plate 23 has its transmission axis 23p substantially parallel to the transmission axis 21a of the linear polarization plate 21, and its reflection axis 23s is aligned with the transmission axis 21a of the linear polarization plate 21. Since they are arranged almost orthogonally, they are incident on the vertical axis phase plate 22 from the direction along the normal line, pass through the vertical axis phase plate 22 without changing the polarization state, and pass through the polarization reflector 23. Most of the incident light, that is, linearly polarized light along the transmission axis 21a of the linearly polarizing plate 21 is transmitted through the polarizing and reflecting plate 23 and is incident on the scattering and reflecting film 24. Is done.

The light scattered and reflected by the scattering reflection film 24 is transmitted through the polarizing reflection plate 23 again and is incident on the vertical axis phase plate 22 from the back side thereof.
The light is emitted as elliptically polarized light to the front side of the longitudinal axis phase plate 22.

That is, the light incident from the direction along the normal line of the vertical phase plate 22 passes through the vertical phase plate 22 with almost no change in the polarization state, and further transmits through the polarization reflection plate 23. Incident on the scattering reflection film 24 from the direction along the normal line. However, since this light is reflected by the scattering reflection film 24 and becomes scattered light, it passes through the polarizing reflection plate 23 again and Most of the light incident on the axial phase plate 22 from the rear side enters the vertical phase plate 22 in a direction obliquely inclined with respect to the normal line, and becomes elliptically polarized light. Out to the front side of.

The light incident on the scattering / reflecting film 24 is linearly polarized light along the transmission axis 23p of the polarizing / reflecting plate 23. The light scattered and reflected by the scattering / reflective film 24 is The light whose state has been disturbed. Therefore, of the light scattered and reflected by the scattering reflection film 24, the light of the polarization component along the reflection axis 23 s of the polarization reflection plate 23 is reflected by the polarization reflection plate 23. The light of the polarization component reflected to the back side and along the transmission axis 23p of the polarization reflection plate 23 passes through the polarization reflection plate 23 and enters the vertical axis phase plate 22 from the back side.

Therefore, the light scattered and reflected by the scattering reflection film 24 and entering the vertical axis phase plate 22 from the back side enters the front surface side, passes through the polarizing reflection plate 23 and passes through the scattering reflection film 24. The intensity of the reflected light, which is disturbed in the polarization state due to the scattered reflection on the scattered reflection film 24, is increased by the amount of the light reflected to the back side by the polarization reflection plate 23, as compared with the intensity of the light incident on the scattered reflection film 24. The reduced light is emitted as elliptically polarized light to the front side of the longitudinal axis phase plate 22.

The elliptically polarized light emitted to the front side of the longitudinal phase plate 22 is incident on the linearly polarized light plate 21 from the back side thereof.
The light of the polarization component along the direction (absorption axis) orthogonal to the transmission axis 21a of the first linear polarization plate 21 is absorbed by the linear polarization plate 21, and the light of the polarization component along the transmission axis 21a of the linear polarization plate 21 is The light reflecting element 2 that transmits through the linear polarizing plate 21
The light is emitted to the front side as the reflected light by 0.

On the other hand, the light (linear polarizing plate 21) incident on the vertical phase plate 22 from a direction obliquely inclined with respect to its normal line.
Linearly polarized light along the transmission axis 21a) passes through the longitudinal axis phase plate 22 as elliptically polarized light, and
3, the light of the polarization component along the reflection axis 23s of the polarization reflector 23 among the elliptically polarized light is reflected by the polarization reflector 23, and is reflected by the transmission axis 23p of the polarization reflector 23. The light of the polarized component along the light passes through the polarizing reflection plate 23 and is incident on the scattering reflection film 24, and is scattered and reflected by the scattering reflection film 24.

The light reflected by the polarization reflector 23 is incident on the vertical phase plate 22 from the back side, and almost all of the light is converted into elliptically polarized light. Light is emitted to the front side.

That is, the light reflected by the polarizing reflector 23 is such that the light incident on the polarizing reflector 23 from a direction oblique to the normal line is reflected at the same reflection angle as the incident angle. Since the light is incident on the vertical phase plate 22 in a direction obliquely inclined with respect to the normal line, most of the light becomes elliptically polarized light and is emitted to the front side of the vertical phase plate 22. .

The light transmitted through the polarizing reflector 23 and scattered and reflected by the scattering reflector 24 passes through the polarizing reflector 23 again and enters the longitudinal phase plate 22 from the back side. Most of the light is emitted as elliptically polarized light to the front side of the longitudinal axis phase plate 22.

At this time, the light incident on the scattering / reflecting film 24 is linearly polarized light along the transmission axis 23p of the polarizing / reflecting plate 23. Is the light whose polarization state is disturbed, and therefore, only the light of the polarization component along the transmission axis 23p of the polarization reflection plate 23 among the light scattered and reflected by the scattering reflection film 24 is this light. Since the light passes through the polarizing reflector 23 and enters the longitudinal phase plate 22 from the back side thereof,
Light that is scattered and reflected by the scattering reflection film 24 and enters the vertical phase plate 22 from the back side is incident on the front side, passes through the polarizing reflection plate 23, and is incident on the scattering reflection film 24. This is light whose intensity is reduced as compared with the intensity, and the light is emitted as elliptically polarized light to the front side of the longitudinal axis phase plate 22.

Then, the elliptically polarized light reflected by the polarization reflection plate 23, transmitted through the longitudinal axis phase plate 22 and emitted to the front side thereof, is reflected by the scattering reflection film 24,
The elliptically polarized light transmitted through the polarization reflector 23 and the longitudinal phase plate 22 and emitted to the front side is incident on the linearly polarized light plate 21 from the back side, and among the elliptically polarized light,
Light having a polarization component along a direction (absorption axis) orthogonal to the transmission axis 21a of the linear polarizing plate 21 is absorbed by the linear polarizing plate 21 and the transmission axis 21 of the linear polarizing plate 21 is absorbed.
The light of the polarization component along a is transmitted through the linear polarizing plate 21 and is emitted to the front side as light reflected by the light reflecting element 20.

As described above, the light reflecting element 20 is incident from the front side, and the linear polarizing plate 21 and the vertical phase plate 2
2 and the light reflected by the polarizing reflector 23 and the light transmitted through the polarizing reflector 23 and the scattering reflector 24.
When the incident light from the front side is the light incident from the direction along the normal line of the longitudinal axis phase plate 22, the light is scattered and reflected. Most of the light is reflected by the scattering reflection film 24 and emitted to the front side, and the incident light from the front side is reflected by the vertical phase plate 22.
When the light is incident from a direction obliquely inclined with respect to the normal line, the light is reflected by the polarization reflection plate 23 and the scattering reflection film 24 and emitted to the front side.

Of these emitted lights, the scattering / reflecting film 2
4 is light whose intensity has been reduced due to the above-mentioned polarization disorder, but the light reflected by the polarization reflector 23 is reflected light having no polarization disorder, and thus the scattering reflection film The light is higher in intensity than the outgoing light reflected by the light 24.

Therefore, the light reflecting element 20 has a reflectance with respect to light incident from a direction along the normal line of the vertical axis phase plate 22 with respect to light incident from a direction oblique to the normal line. It has an angle selective reflection characteristic smaller than the reflectance.

Therefore, by arranging the light reflection element 20 on the back side of the scattering / transmission type liquid crystal element 1, a scattering type liquid crystal display device having a sufficient bright display and a good contrast can be constituted. .

The light reflecting element 20 used in this embodiment
Since the polarization reflection plate 23 is disposed with the transmission axis 23p of the polarization reflection plate 23 substantially parallel to the transmission axis 21a of the linear polarization plate 21, the light is incident from the direction along the normal to the vertical axis phase plate 22. The difference between the reflectance with respect to the reflected light and the reflectance with respect to light incident from a direction oblique to the normal line can be further increased.

The scattering type liquid crystal display device of this embodiment uses external light which is the light of the use environment to control and display the light scattering by the liquid crystal layer 6 of the scattering / transmission type liquid crystal element 1. When an off-voltage is applied between the electrodes 4 and 5 of the liquid crystal element 1 so that the liquid crystal molecules 8a of the liquid crystal layer 6 are oriented in a random direction, the display of the pixel area becomes bright. When an on-voltage is applied between the electrodes 4 and 5 so that the liquid crystal molecules 8a are oriented substantially perpendicular to the surfaces of the substrates 2 and 3, the display of the pixel region becomes dark.

That is, when an off voltage is applied between the electrodes 4 and 5 of the scattering / transmission type liquid crystal element 1 so that the liquid crystal molecules 8a of the liquid crystal layer 6 are oriented in a random direction. When the liquid crystal element 8a is oriented so as to scatter incident light, the light transmission path at that time is indicated by an arrow in FIG. The light scattered by 6 and directed toward the front surface of the liquid crystal element 1 out of the scattered light is emitted forward.

Of the light scattered by the liquid crystal layer 6, light traveling toward the back of the liquid crystal element 1 is
And is incident on the light reflecting element 20 from the front side.

At this time, the light emitted to the back side of the liquid crystal element 1 is scattered light, and most of the light is applied to the light reflection element 20 at an angle with respect to the normal to the vertical axis phase plate 22. Incident from the direction inclined to.

Therefore, most of the light incident on the light reflecting element 20 from the front side thereof and transmitted through the linear polarizing plate 21 to be linearly polarized light is converted to elliptically polarized light by the vertical phase plate 22. The transmitted light is incident on the polarized light reflector 23, and of the light, the light of the polarized component along the reflection axis 23 s of the polarized light reflector 23 is reflected by the polarized light reflector 23, and the reflected light is reflected on the vertical axis phase. The light passes through the plate 22 and the linear polarizing plate 21 and is emitted to the front side of the light reflecting element 20.

Also, of the light transmitted through the vertical axis phase plate 22 as elliptically polarized light and incident on the polarized light reflection 23,
The light of the polarization component along the transmission axis 23p of the polarization reflection plate 23 is transmitted through the polarization reflection plate 23 and is scattered and reflected by the scattering reflection film 24, and the light is transmitted to the polarization reflection plate 23 and the vertical axis phase plate. The light passes through 22 and the linear polarizing plate 21 and is emitted to the front side of the light reflecting element 20.

Then, the reflected light emitted to the front side of the light reflecting element 20, that is, the light reflected by the polarizing reflector 23 and the light reflected by the scattering reflecting film 24 are transmitted to the liquid crystal element 1. The light is incident again from the rear side and is scattered by the liquid crystal layer 6, and of the scattered light, light directed toward the front surface of the liquid crystal element 1 is emitted forward.

Therefore, according to this scattering type liquid crystal display device, bright display is incident on the liquid crystal element 1 from the front and the liquid crystal layer 6
Of the light scattered by the liquid crystal element 1 and the light that is emitted forward, is emitted to the back side of the liquid crystal element 1, is reflected by the light reflection element 20, is transmitted again through the liquid crystal element 1, and is scattered by the liquid crystal layer 6. The light can be displayed by the light emitted forward in the light.

In this embodiment, the light reflected by the light reflection element 20 is both the light reflected by the polarization reflection plate 23 and the light reflected by the scattering reflection film 24. The light scattered and reflected by the scattering reflection film 24 is light whose intensity has been reduced due to the disturbance of polarization, but the light reflected by the polarization reflection plate 23 (reflected light having no disturbance of polarization) is the scattered reflection. The light has higher intensity than the light reflected by the film 24.

Therefore, the light reflected by the light reflecting element 20 at the time of bright display is light having a higher intensity than the light reflected by the light reflecting element 10 at the time of bright display in the first embodiment. The reflected light enters the liquid crystal element 1 from the back side, is scattered by the liquid crystal layer 6, and is emitted forward.

Therefore, according to the scattering type liquid crystal device of this embodiment, the scattering type liquid crystal device of the first embodiment is more effective than that of the first embodiment.
A brighter bright display can be obtained.

This bright display is a white display without banding, and the light emitted forward is scattered light having a substantially uniform intensity distribution scattered by the liquid crystal layer 6 of the liquid crystal element 1. The display brightness when viewed from the front direction, which is the normal viewing direction, that is, the direction near the normal line of the screen of the liquid crystal element 1, is sufficient.

Further, an on-voltage was applied between the electrodes 4 and 5 of the scattering / transmission type liquid crystal element 1 so that the liquid crystal molecules 8a of the liquid crystal layer 6 were oriented almost perpendicular to the substrates 2 and 3. At that time, that is, when the liquid crystal molecules 8a are aligned in an alignment state in which the incident light is transmitted without being scattered, the light transmission path at that time is, as indicated by an arrow in FIG. The light that has entered the liquid crystal element 1 transmits through the liquid crystal layer 6 with little scattering, exits to the rear side of the liquid crystal element 1, and enters the light reflection element 20 from the front side.

FIG. 3 shows only the path of light incident from the direction along the normal line of the screen of the liquid crystal element 1. However, since external light enters the liquid crystal element 1 at various incident angles. When the liquid crystal molecules 8a are oriented so as to transmit incident light with little scattering, incident light from the front exits to the back side of the liquid crystal element 1 at various exit angles corresponding to the incident angles. Are incident on the light reflecting element 20 at various incident angles.

The light transmitted through the liquid crystal element 1 and incident on the light reflecting element 20 from the front side thereof is transmitted through the linear polarizing plate 21 to become linearly polarized light and is incident on the vertical phase plate 22.
Of the light, light incident from a direction along the normal to the vertical phase plate 22 passes through the vertical phase plate 22 with almost no change in the polarization state. The light passes through the polarizing reflector 23 disposed substantially parallel to the transmission axis 21 a of the plate 21 and is scattered and reflected by the scattering reflector 24.

The light scattered and reflected by the scattering reflection film 24 is transmitted through the polarization reflection plate 23 to reduce the intensity as described above, and is transmitted through the vertical axis phase plate 22 and the linear polarization plate 21 to be forwardly transmitted. Out.

The linearly polarized light (not shown) incident on the ordinate phase plate 22 from a direction oblique to the normal line is transmitted through the ordinate phase plate 22 as elliptically polarized light. Then, of the elliptically polarized light, the light of the polarization component along the reflection axis 23s of the polarization reflection plate 23 is reflected by the polarization reflection plate 23, and the transmission axis 2
The light of the polarization component along 3p is transmitted through the polarization reflection plate 23 and is scattered and reflected by the scattering reflection film 24.

The light reflected by the polarizing reflector 23 passes through the longitudinal phase plate 22 and the linear polarizing plate 21 and exits forward, and the light scattered and reflected by the scattering reflector 24 is Then, the light passes through the polarizing reflector 23 to reduce the intensity, and passes through the ordinate phase plate 22 and the linear polarizing plate 21 to be emitted forward.

However, the light reflected by the polarization reflection plate 23, transmitted through the vertical axis phase plate 22 and the linear polarization plate 21, and emitted forward enters the light reflection element 20 from an oblique direction. This light is reflected by the polarizing reflection plate 230 at the same reflection angle as the incident angle, and the emitted light is emitted in a direction inclined obliquely to the front direction. Has little effect.

Therefore, the liquid crystal molecules 8a of the liquid crystal element 1
The display observed from the front when the liquid crystal molecules are aligned in an alignment state in which incident light is transmitted with little scattering is incident on the liquid crystal element 1 from a direction along a normal line of the longitudinal axis phase plate 22. Of the light scattered and reflected by the scattering reflection film 24 and the light incident on the liquid crystal element 1 from a direction obliquely inclined with respect to the normal of the longitudinal axis phase plate 22, the light is scattered and reflected by the scattering reflection film 24. This is a display of brightness corresponding to the intensity of the light.

That is, the liquid crystal molecules 8a of the liquid crystal element 1
Is a dark display having a sufficient light-to-dark ratio with respect to the bright display.

Therefore, according to the scattering type liquid crystal display device of this embodiment, the bright display is made sufficiently brighter than that of the scattering type liquid crystal display device of the above-described first embodiment.
The dark display is made sufficiently dark, and a better contrast can be obtained as compared with a conventional scattering type liquid crystal display device in which a reflection film (specular reflection film or scattering reflection film) is arranged on the back side of the scattering / transmission type liquid crystal element. .

Further, in the scattering type liquid crystal display device of this embodiment, the light reflecting element 20 is arranged such that the polarizing reflection plate 23 is arranged such that its transmission axis 23p is substantially parallel to the transmission axis 21a of the linear polarizing plate 21. Therefore, the reflectance of the light reflecting element 20 with respect to light incident from a direction along the normal line of the vertical axis phase plate 22 and the reflectance with respect to light incident from a direction oblique to the normal line And a scattering type liquid crystal display device having a better contrast can be configured.

The linear reflection plate 2 of the light reflection element 20
The transmission axis 21a of 1 and the transmission axis 23p of the polarizing reflection plate 23 are not limited to be substantially parallel, but an angle range smaller than 45 degrees (preferably an angle range of 30 degrees or less, more preferably an angle range of 15 degrees or less). May cross at the intersection angle of
The transmission axes 21a of the linear polarizing plate 21 and the polarizing reflecting plate 23,
If the intersection angle of 23p is within this range, the light reflecting element 2
The angle-selective reflection characteristic of 0 indicates that the reflectance for light incident from a direction along the normal of the vertical axis phase plate 22 is smaller than the reflectance for light incident from a direction oblique to the normal. As a characteristic, a scattering type liquid crystal display device having sufficient brightness for bright display and good contrast can be constructed.

[Third Embodiment] FIG. 4 is an exploded perspective view of a scattering type liquid crystal display device according to a third embodiment of the present invention.
(A) shows a light transmission path when the liquid crystal molecules 8a of the scattering / transmission type liquid crystal element 1 are aligned in an alignment state that scatters incident light, and (b) shows that the liquid crystal molecules 8a of the liquid crystal element 1 FIG. 3 shows a light transmission path when the light is oriented in an orientation state in which incident light is transmitted with little scattering.

In the scattering type liquid crystal display device of this embodiment, on the back side of the scattering / transmission type liquid crystal element 1, the back film (scattering reflection film 2) of the light reflecting element 20 of the second embodiment shown in FIG.
4) A light reflecting element 20 having a configuration in which a light absorbing film 25 is replaced.
a is arranged, and the other configuration is the same as that of the second embodiment.

The light reflecting element 20a of this embodiment enters from the front side, and receives the linear polarizing plate 21 and the vertical phase plate 22.
And the reflection axis 2 of the polarizing reflection plate 23
The light of the polarization component along 3s is reflected by the scattering reflection film 24, and the reflected light is emitted to the front side.

That is, the light incident on the light reflecting element 20a from the front side is first absorbed by the linear polarizing plate 21 into the light of the polarization component along the direction (absorption axis) orthogonal to the transmission axis 21a. Then, the light is converted into linearly polarized light along the transmission axis 21a of the linearly polarizing plate 21 and is incident on the vertical axis phase plate 22.

Among the linearly polarized light incident on the vertical axis phase plate 22, the light incident on the vertical axis phase plate 22 from the direction along the normal thereof changes the polarization state of the vertical axis phase plate 22 almost. The linearly polarized light is transmitted without being incident on the polarizing reflection plate 23 as it is, and the light incident from the direction obliquely inclined with respect to the normal line has a phase difference in the process of transmitting through the vertical axis phase plate 22. Then, the light is converted into elliptically polarized light and enters the polarization reflector 23.

The polarizing reflector 23 has its transmission axis 23p substantially parallel to the transmission axis 21a of the linear polarizing plate 21 and the reflection axis 23s, as in the second embodiment.
Is arranged substantially perpendicular to the transmission axis 21a of the linear polarizing plate 21, and thus is incident on the vertical axis phase plate 22 from a direction along the normal line, and changes the polarization state of the vertical axis phase plate 22. Most of the light that has passed through and entered the polarizing reflector 23, that is, the linearly polarized light along the transmission axis 21 a of the linear polarizing plate 21, is transmitted through the polarizing reflector 23 and is absorbed by the light absorbing film 25. Absorbed.

On the other hand, the light incident on the vertical axis phase plate 22 from a direction obliquely inclined with respect to its normal (the linear polarizing plate 21).
Linearly polarized light along the transmission axis 21a) passes through the longitudinal axis phase plate 22 as elliptically polarized light, and
3, the light of the polarization component along the reflection axis 23s of the polarization reflector 23 among the elliptically polarized light is reflected by the polarization reflector 23, and is reflected by the transmission axis 23p of the polarization reflector 23. The light of the polarized component along the transmitted light passes through the polarizing reflector 23 and is absorbed by the light absorbing film 25.

The light reflected by the polarization reflection plate 23 is incident on the vertical axis phase plate 22 from the back side, and almost all of the light is converted into elliptically polarized light. Light is emitted to the front side.

That is, as for the light reflected by the polarizing reflector 23, the light incident on the polarizing reflector 23 from a direction oblique to the normal line is reflected at the same reflection angle as the incident angle. Since the light is incident on the ordinate phase plate 22 in a direction obliquely inclined with respect to the normal line, most of the light becomes elliptically polarized light and becomes
Out to the front side of.

The elliptically polarized light reflected by the polarization reflection plate 23, transmitted through the vertical axis phase plate 22 and emitted to the front side enters the linear polarization plate 21 from the back side,
Of the elliptically polarized light, the transmission axis 2 of the linear polarizing plate 21
The light of the polarization component along the direction (absorption axis) orthogonal to 1a is absorbed by the linear polarizing plate 21, and the light of the polarization component along the transmission axis 21a of the linear polarizing plate 21 is converted into the linearly polarized light. The light passes through the plate 21 and is emitted to the front side as light reflected by the light reflecting element 20a.

As described above, the light reflecting element 20a receives the light incident from the front side, transmits the linear polarizing plate 21 and the vertical axis phase plate 22 and reflects the light reflected by the polarizing reflecting plate 23 on the front side. When the incident light from the front side is the light incident from the direction along the normal line of the longitudinal axis phase plate 22, most of the light is transmitted through the polarizing reflector 23. And absorbed by the light absorbing film 25.

When the incident light from the front side is incident from a direction oblique to the normal to the longitudinal axis phase plate 22, the light transmitted through the polarizing reflection plate 23 out of the light. The light of the polarization component along the axis 23p is
3 is absorbed by the light absorbing film 25 and the light of the polarization component along the reflection axis 23s of the polarization reflection plate 23 is reflected by the polarization reflection plate 23.

Therefore, the light reflecting element 20a has a reflectance with respect to light incident from a direction along the normal of the vertical axis phase plate 22 with respect to light incident from a direction oblique to the normal. It has an angle selective reflection characteristic smaller than the reflectance.

Therefore, by disposing the light reflecting element 20a on the back side of the scattering / transmission type liquid crystal element 1,
A scattering type liquid crystal display device having a sufficient bright display and a good contrast can be configured.

The light reflecting element 20 used in this embodiment was used.
a is such that the polarization reflection plate 23 is arranged such that the transmission axis 23p of the polarization reflection plate 23 is substantially parallel to the transmission axis 21a of the linear polarization plate 21, and the light absorbing film 25 on the back surface is a black film. A larger difference between the reflectance for light incident from a direction along the normal line of the vertical axis phase plate 22 and the reflectance for light incident from a direction oblique to the normal line, The reflectance for light incident from a direction along the normal line of the vertical axis phase plate 22 is substantially zero,
The dark display of the scattering type liquid crystal display device can be made close to black.

The scattering type liquid crystal display device of this embodiment uses external light which is the light of the use environment to control and display the light scattering by the liquid crystal layer 6 of the scattering / transmission type liquid crystal element 1. When an off-voltage is applied between the electrodes 4 and 5 of the liquid crystal element 1 so that the liquid crystal molecules 8a of the liquid crystal layer 6 are oriented in a random direction, the display of the pixel area becomes bright. When an on-voltage is applied between the electrodes 4 and 5 so that the liquid crystal molecules 8a are oriented substantially perpendicular to the surfaces of the substrates 2 and 3, the display of the pixel region becomes dark.

That is, when an off-voltage is applied between the electrodes 4 and 5 of the scattering / transmission type liquid crystal element 1 so that the liquid crystal molecules 8a of the liquid crystal layer 6 are oriented in a random direction. When the liquid crystal element 8a is oriented so as to scatter incident light, the light transmission path at that time is indicated by an arrow in FIG. The light scattered by 6 and directed toward the front surface of the liquid crystal element 1 out of the scattered light is emitted forward.

Of the light scattered by the liquid crystal layer 6, the light traveling toward the back of the liquid crystal element 1
Of the light reflecting element 20a and enters the light reflecting element 20a from the front side.

At this time, the light emitted to the back side of the liquid crystal element 1 is the scattered light, and most of the light is obliquely transmitted to the light reflecting element 20a with respect to the normal to the vertical axis phase plate 22. Incident on the light reflecting element 2
Most of the light that has been incident on the light receiving surface 0a from the front side thereof and transmitted through the linear polarizing plate 21 to become linearly polarized light is transmitted as the elliptically polarized light through the vertical axis phase plate 22 and is incident on the polarization reflection 23. Of the light, the reflection axis 23s of the polarization reflection plate 23
Is reflected by the polarization reflection plate 23, and the reflected light passes through the longitudinal axis phase plate 22 and the linear polarization plate 21 and is emitted to the front side of the light reflection element 20a.

The light transmitted through the longitudinal axis phase plate 22 and converted into elliptically polarized light and incident on the polarized light reflection 23 is
The light of the polarization component along the transmission axis 23p of the polarization reflection plate 23 passes through the polarization reflection plate 23 and is absorbed by the light absorbing film 25.

The reflected light emitted to the front side of the light reflecting element 20a, that is, the light reflected by the polarizing reflector 23, enters the liquid crystal element 1 from the back side again and is reflected by the liquid crystal layer 6. The light scattered and directed to the front surface of the liquid crystal element 1 out of the scattered light is emitted forward.

Therefore, according to this scattering type liquid crystal display device, a bright display is incident on the liquid crystal element 1 from the front and the liquid crystal layer 6
Of the light scattered by the liquid crystal element 1 and the light that is emitted forward, is emitted to the back side of the liquid crystal element 1 and is reflected by the light reflection element 20a, passes through the liquid crystal element 1 again, and
Of the light scattered by the light emitted forward.

According to this scattering type liquid crystal display device, a bright display enters the liquid crystal element 1 from the front and is emitted out of the light scattered by the liquid crystal layer 6 to the front.
Out of the light reflected by the light reflecting element 20a, transmitted through the liquid crystal element 1 again, and scattered by the liquid crystal layer 6, and can be displayed by light emitted forward. A conventional scattering type liquid crystal display device in which a light absorbing film is disposed on the back side of a scattering / transmission type liquid crystal element (a bright display is emitted from the front of light scattered by the liquid crystal layer after being incident on the liquid crystal element from the front). Display only with light
, A bright display with sufficient brightness can be obtained.

This bright display is a white display without banding, and the light emitted forward is scattered light having a substantially uniform intensity distribution scattered by the liquid crystal layer 6 of the liquid crystal element 1. The display brightness when viewed from the front direction, which is the normal viewing direction, that is, the direction near the normal line of the screen of the liquid crystal element 1, is sufficient.

An ON voltage was applied between the electrodes 4 and 5 of the scattering / transmission type liquid crystal element 1 so that the liquid crystal molecules 8a of the liquid crystal layer 6 were oriented almost perpendicular to the substrates 2 and 3. In other words, when the liquid crystal molecules 8a are aligned in an alignment state in which incident light is transmitted with little scattering, the light transmission path at that time is indicated by an arrow in FIG. The light that has entered the liquid crystal element 1 transmits through the liquid crystal layer 6 with almost no scattering, exits to the rear side of the liquid crystal element 1, and enters the light reflection element 20a from the front side.

Although FIG. 4 shows only the path of light incident from the direction along the normal line of the screen of the liquid crystal element 1, external light enters the liquid crystal element 1 at various incident angles. When the liquid crystal molecules 8a are oriented so as to transmit incident light with little scattering, incident light from the front exits to the back side of the liquid crystal element 1 at various exit angles corresponding to the incident angles. Are incident on the light reflecting element 20a at various incident angles.

The light transmitted through the liquid crystal element 1 and incident on the light reflecting element 20a from the front side is reflected by the linear polarizing plate 21a.
Is transmitted as a linearly polarized light and is incident on the vertical axis phase plate 22, and of the light, the light incident from the direction along the normal to the vertical axis phase plate 22 is almost unchanged. The light passes through the vertical phase plate 22 and further passes through the transmission axis 23.
p is transmitted through a polarizing reflector 23 disposed substantially parallel to the transmission axis 21 a of the linear polarizing plate 21 and is absorbed by the light absorbing film 25.

Further, linearly polarized light (not shown) incident on the ordinate phase plate 22 from a direction oblique to its normal is transmitted through the ordinate phase plate 22 as elliptically polarized light. Then, of the elliptically polarized light, the light of the polarization component along the transmission axis 23p of the polarizing reflector 23 is transmitted through the polarizing reflector 23 and the light absorbing film 25 is transmitted. Is absorbed by

On the other hand, of the elliptically polarized light incident on the polarizing reflector 23, light having a polarization component along the reflection axis 23s of the polarizing reflector 23 is reflected by the polarizing reflector 23, and the ordinate phase is reflected. The light passes through the plate 22 and the linear polarizing plate 21 and is emitted forward. This light is incident on the light reflecting element 20 in an oblique direction, and is reflected by the polarizing reflecting plate 230 at the same reflection angle as the incident angle. Since the light is emitted and emitted in a direction oblique to the front direction, this light hardly affects the brightness of the display.

Therefore, the liquid crystal molecules 8a of the liquid crystal element 1
The display observed from the front direction when the liquid crystal is oriented to an alignment state in which the incident light is transmitted with little scattering is a display close to black.

Therefore, according to the scattering type liquid crystal display device of this embodiment, a bright display can be made sufficiently bright, and a dark display can be made to be a display close to black, so that good contrast can be obtained.

[Fourth Embodiment] FIG. 5 is an exploded perspective view of a scattering type liquid crystal display device according to a fourth embodiment of the present invention.
(A) shows a light transmission path when the liquid crystal molecules 8a of the scattering / transmission type liquid crystal element 1 are aligned in an alignment state that scatters incident light, and (b) shows that the liquid crystal molecules 8a of the liquid crystal element 1 FIG. 3 shows a light transmission path when the light is oriented in an orientation state in which incident light is transmitted with little scattering.

In the scattering type liquid crystal display device of this embodiment, the polarizing reflector 23 of the light reflecting element 20 of the second embodiment shown in FIG. A light reflecting element 20b having a configuration in which the light reflecting element 20b is replaced by a selective reflection plate 23 'made of, is the same as that of the second embodiment.

The selective reflection plate 23 ′ made of the cholesteric liquid crystal layer is made of, for example, a cholesteric polymer liquid crystal.
A cholesteric liquid crystal film polymerized while maintaining a cholesteric phase at a predetermined pitch, and among light incident from the front surface, a circularly polarized component around one of the right and left and wavelength light in a predetermined wavelength band is directed forward. It has a selective reflection characteristic that reflects light, transmits other light, and emits it to the back side. Hereinafter, this selective reflection plate 23 'is referred to as a cholesteric liquid crystal film.

That is, in the cholesteric liquid crystal film 23 ', the twist direction of the cholesteric liquid crystal molecules 22 is clockwise or counterclockwise when viewed from the front side.
Is reflected by a circularly polarized light component around the same direction as the twisting direction of the cholesteric liquid crystal, and reflects light in a reflection wavelength band determined by the average refractive index of the cholesteric liquid crystal and the twist pitch of the cholesteric liquid crystal molecules a, and reflects light in other wavelength bands. Let go through without doing.

The cholesteric liquid crystal film 23 'used in this embodiment has a reflection wavelength band that covers almost the entire visible light band. Therefore, light reflected by the cholesteric liquid crystal film 23' is , White light without banding.

The light reflection element 20b is obtained by replacing the polarization reflection plate 23 in the light reflection element 20 of the second embodiment with a cholesteric liquid crystal film 23 ', and the cholesteric liquid crystal film 23' has a predetermined polarization. The selective reflection characteristic of reflecting the incident light of the component and transmitting the incident light of another polarized component is basically the same as that of the polarizing reflector.

For this reason, like the light reflecting element 20 of the second embodiment, the light reflecting element 20b has a vertical axis
2 has a smaller angle-selective reflection characteristic than the reflectance for light incident from a direction along the normal to the light incident from a direction oblique to the normal, and This light reflecting element 20b is
By arranging it on the back side of the transmission type liquid crystal element 1, a scattering type liquid crystal display device having sufficient bright display brightness and good contrast can be configured.

In the scattering type liquid crystal display device of this embodiment, the light reflecting element 20b has a cholesteric liquid crystal film 23 'as a selective reflection plate which reflects incident light having a predetermined polarization component and transmits incident light having another polarization component. However, the optical characteristics of the light reflection element 20b are substantially the same as those of the light reflection element 20 of the second embodiment using the polarization reflection plate 23 as the selective reflection plate.

Therefore, in this scattering type liquid crystal display device, the transmission path when the liquid crystal molecules 8a of the liquid crystal element 1 are aligned in an alignment state that scatters incident light, and the liquid crystal molecules 8a of the liquid crystal element 1 almost scatter incident light. The light transmission path when the light is oriented in the orientation state in which the light is transmitted without passing through
Since it is almost the same as the scattering type liquid crystal display device of the embodiment,
The description is omitted.

In the scattering type liquid crystal display device of this embodiment, the reflection wavelength band of the cholesteric liquid crystal film 23 'of the light reflection element 20b is a band covering almost the entire visible light band. And the dark display can be a display without banding.

The scattering type liquid crystal display device of the fourth embodiment uses the scattering film 24 as the back film of the light reflecting element 20b. The same display as the scattering type liquid crystal display device shown in FIG. 4 can be performed.

The liquid crystal display device of each of the above-described embodiments is for displaying a black-and-white image. However, the liquid crystal display device of each of the embodiments corresponds to each pixel region on the inner surface of one of the substrates of the scattering / transmission type liquid crystal element 1. If a plurality of color filters, for example, three color filters of red, green, and blue, are provided, a multicolor image such as a full-color image can be displayed.

Further, in the liquid crystal display device of each embodiment, the front / rear surface of the scattering / transmission type liquid crystal element 1 or at least one layer (for example, the first layer) of the laminated structure of the light reflecting elements 10, 20, 20a and 20b is provided. In the case of the embodiment, between the first linear polarizer 11 and the vertical phase plate 12, between the vertical phase plate 22 and the second linear polarizer 13, and the second linear polarizer A configuration in which a light diffusion film is disposed between at least one of the layers between the plate 13 and the reflection film 14) may be adopted, and thus the viewing angle can be widened.

The scattering / transmission type liquid crystal element 1 is not limited to a polymer dispersion type, but a cholesteric liquid crystal having a positive dielectric anisotropy or a mixed liquid crystal of a cholesteric liquid crystal and a nematic liquid crystal is provided between a pair of transparent substrates. Phase transition type (also called a phase transition type) provided with a liquid crystal layer made of

This phase transition type liquid crystal element scatters and transmits light by utilizing the phase transition of liquid crystal, and is in an electric field free state in which no voltage is applied between electrodes provided on the inner surfaces of a pair of substrates. In the above, the liquid crystal exhibits a cholesteric liquid crystal phase and scatters incident light. In addition, when a predetermined voltage is applied between the electrodes, the liquid crystal transitions to a nematic liquid crystal phase in a homeotropic arrangement, and transmits incident light with almost no scattering.

Further, the scattering / transmission type liquid crystal element 1 is
The liquid crystal display device is not limited to the active matrix type, but may be a simple matrix type. In the case of a monochrome liquid crystal display device, a segment type may be used.

Further, the light reflecting elements 10 and 2 of each of the above-described embodiments are used.
0, 20a and 20b are not limited to the scattering type liquid crystal display device,
It can be used for other purposes.

[0176]

According to the light reflecting element of the present invention, a first linear polarizing plate, a phase plate having an optical axis in a thickness direction, a second linear polarizing plate, and a reflecting film are sequentially laminated from the front side. Out of light that enters from the front side, passes through the first linear polarizer, the phase plate, and the second linear polarizer, is reflected by the reflection film, and exits to the front side. And the phase plate has an angle-selective reflection characteristic in which the reflectance for light incident from a direction along the normal to the phase plate is smaller than the reflectance for light incident from a direction oblique to the normal. Therefore, by arranging this light reflection element on the back side of the scattering / transmission type liquid crystal element, a scattering type liquid crystal display device having sufficient brightness of bright display and good contrast can be constituted.

In this light reflecting element, it is desirable that the second linearly polarizing plate is arranged so that its transmission axis is substantially orthogonal to the transmission axis of the first linearly polarizing plate. The dark display of the scattering type liquid crystal display device can be made substantially black.

The scattering type liquid crystal display device of the present invention has
A first linear polarizing plate, a phase plate having an optical axis in a thickness direction, and a second linear polarizing plate on the back side of the transmission type liquid crystal element;
A reflection film and a reflection film are arranged in order from the front side, are incident from the front side, pass through the first linear polarizing plate, the phase plate, and the second linear polarizing plate, and are reflected by the reflection film. Out of the light emitted to the front side, the reflectance for light incident from a direction along the normal to the phase plate is smaller than the reflectance for light incident from a direction oblique to the normal. Since the light reflection element having the selective reflection characteristic is arranged, the bright display can be made sufficiently bright and a good contrast can be obtained.

Another light reflecting element of the present invention is a linear polarizing plate, a phase plate having an optical axis in the thickness direction, and reflecting incident light of a predetermined polarization component and transmitting incident light of another polarization component. A selective reflection plate and a back film composed of a scattering reflection film or a light absorption film are sequentially laminated from the front side, and are incident from the front side, pass through the linear polarizing plate and the phase plate, and selectively reflect the light. The light reflected by the plate and emitted to the front side, or the light reflected by the selective reflection plate and emitted to the front side and transmitted through the selective reflection plate and scattered and reflected by the back film made of the scattering reflection film to form the front surface Out of the light emitted to the side, the reflectivity for light incident from a direction along the normal to the phase plate is smaller than the reflectivity for light incident from a direction oblique to the normal. Has reflective properties Because it is, by disposing the light reflecting elements on the rear side of the scattering / transmission type liquid crystal element, it is possible brightness of the bright display constitutes an even better scattering type liquid crystal display device sufficiently contrast.

In this light reflection element, when the selective reflection plate is the polarization reflection plate, it is desirable that the polarization reflection plate is arranged with its transmission axis substantially parallel to the transmission axis of the linear polarization plate. By doing so, the reflectance for light incident from a direction along the normal to the phase plate,
The difference from the reflectance with respect to light incident from a direction obliquely inclined with respect to the normal line can be further increased, so that a scattering type liquid crystal display device having better contrast can be configured.

When the selective reflection plate is made of the cholesteric liquid crystal layer, it is desirable that the reflection wavelength band is a band covering almost the entire visible light band. The bright display and the dark display can be displayed without banding.

Another scattering type liquid crystal display device of the present invention comprises a linear polarizing plate, a phase plate having an optical axis in a thickness direction, and a predetermined polarization component on the back side of a scattering / transmission type liquid crystal element. A selective reflection plate that reflects light and transmits incident light of another polarization component, and a back film made of a scattering reflection film or a light absorption film are laminated and arranged in order from the front side. The light transmitted through the plate and the phase plate and reflected by the selective reflection plate and emitted to the front side, or the light reflected by the selective reflection plate and emitted to the front side and transmitted through the selective reflection plate, and A direction in which, among the lights scattered and reflected by the back film made of the scattering reflection film and emitted to the front side, the reflectance for light incident from a direction along the normal to the phase plate is oblique to the normal. From the reflectance for light incident from Small angle selected are those in which a light reflecting element having a reflecting property is disposed, therefore, with sufficiently bright to bright display, it is possible to obtain a good contrast.

In this scattering type liquid crystal display device, if the back film of the light reflection element is a scattering reflection film, the light enters the scattering / transmission type liquid crystal element from the front, emits to the back side of the liquid crystal element, and Of the light incident on the light reflection element from the front side, the light reflected by the selective reflection plate through the linear polarizing plate and the phase plate and the light reflected by the selective reflection plate and transmitted through the selective reflection plate by the scattering reflection film. Since both the scattered and reflected light is emitted to the front side of the light reflecting element, more reflected light can be made incident on the liquid crystal element from the back side to increase the screen brightness.

In this scattering type liquid crystal display device,
If the back film of the light reflecting element is a light absorbing film, light incident on the scattering / transmission type liquid crystal element from the front, emitted to the back side of the liquid crystal element, and incident on the light reflecting element from the front side thereof. The light transmitted through the linear polarizer and the phase plate and reflected by the selective reflection plate is emitted to the front side of the light reflection element and is incident on the liquid crystal element from the back side, and the selection is performed. Since the light transmitted through the reflection plate is absorbed by the light absorbing film, a dark display can be made close to black, and good contrast can be obtained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a scattering type liquid crystal display device according to a first embodiment of the present invention, in which (a) is a state in which liquid crystal molecules of a scattering / transmission type liquid crystal element are aligned to scatter incident light. (B) shows a light transmission path when the liquid crystal molecules of the liquid crystal element are aligned in an alignment state in which incident light is transmitted with little scattering.

FIG. 2 is a cross-sectional view of a part of the scattering / transmission type liquid crystal element 1.

FIG. 3 is an exploded perspective view of a scattering type liquid crystal display device according to a second embodiment of the present invention, in which (a) is a state in which liquid crystal molecules of a scattering / transmission type liquid crystal element are aligned to scatter incident light. (B) shows a light transmission path when the liquid crystal molecules of the liquid crystal element are aligned in an alignment state in which incident light is transmitted with little scattering.

FIG. 4 is an exploded perspective view of a scattering-type liquid crystal display device according to a third embodiment of the present invention, in which (a) is a state in which liquid crystal molecules of a scattering / transmission type liquid crystal element are aligned so as to scatter incident light. (B) shows a light transmission path when the liquid crystal molecules of the liquid crystal element are aligned in an alignment state in which incident light is transmitted with little scattering.

FIG. 5 is an exploded perspective view of a scattering type liquid crystal display device according to a fourth embodiment of the present invention, in which (a) is a state in which liquid crystal molecules of a scattering / transmission type liquid crystal element are aligned so as to scatter incident light. (B) shows a light transmission path when the liquid crystal molecules of the liquid crystal element are aligned in an alignment state in which incident light is transmitted with little scattering.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Scattering / transmission type liquid crystal element 2,3 ... Substrate 4,5 ... Electrode 6 ... Liquid crystal layer (liquid crystal / polymer composite layer) 10,20,20a, 20b ... Light reflection element 11,13,21 ... Linear polarizing plate 11a, 13a, 21a: transmission axis 12, 22, vertical axis phase plate 12a, 22a: optical axis 14: reflection film 23: polarization reflection plate (selective reflection plate) 23s: reflection axis 23p: transmission axis 23 ': cholesteric liquid crystal film (Selective reflection plate) 24 scattering reflection film 25 light absorption film

Claims (7)

[Claims] 1. A first linear polarizing plate, a phase plate having an optical axis in a thickness direction, a second linear polarizing plate, and a reflection film are sequentially stacked and arranged from a front side. Of the light that enters, passes through the first linear polarizing plate, the phase plate, and the second linear polarizing plate, is reflected by the reflection film, and is emitted to the front side, the light is incident on the normal to the phase plate. A light-reflecting element, wherein the light-reflecting element has an angle-selective reflection characteristic in which the reflectance for light incident from a direction along the direction is smaller than the reflectance for light incident from a direction oblique to the normal line. . 2. The light reflecting element according to claim 1, wherein the second linearly polarizing plate is arranged so that its transmission axis is substantially orthogonal to the transmission axis of the first linearly polarizing plate. 3. A pair of substrates each having electrodes provided on inner surfaces facing each other, and disposed between the pair of substrates, and controls scattering and transmission of incident light according to an electric field applied between the electrodes. A scattering / transmission type liquid crystal element comprising a liquid crystal layer; and a light reflection element disposed on the back side of the scattering / transmission type liquid crystal element, wherein the light reflection element has a first linear polarizer, A phase plate having an optical axis in the direction, a second linear polarizer, and a reflective film are sequentially stacked from the front side, and are incident from the front side, and the first linear polarizer and the phase plate Among the light transmitted through the second linear polarizer and reflected by the reflection film and emitted to the front side, the reflectance for light incident from a direction along the normal to the phase plate is the normal. Than the reflectance for light incident from a direction inclined to A scattering type liquid crystal display device having a small angle selective reflection characteristic. 4. A linear polarizing plate, a phase plate having an optical axis in a thickness direction, a selective reflecting plate for reflecting incident light of a predetermined polarization component and transmitting incident light of another polarization component, and a scattering reflection film. Alternatively, a back film composed of a light absorbing film and a rear film are sequentially laminated from the front side, incident on the front side, transmitted through the linear polarizing plate and the phase plate, reflected by the selective reflection plate, and reflected on the front side. Outgoing light, or light reflected by the selective reflection plate and emitted to the front side and light transmitted through the selective reflection plate and scattered and reflected by the back film made of the scattering reflection film and emitted to the front side, The reflectivity for light incident from a direction along the normal line of the phase plate has an angle selective reflection characteristic smaller than the reflectivity for light incident from a direction oblique to the normal line. A light reflecting element characterized by the above-mentioned. 5. The selective reflection plate has a reflection axis and a transmission axis in directions substantially orthogonal to each other, reflects incident light of a polarization component along the reflection axis, and receives incident light of a polarization component along the transmission axis. 5. The light according to claim 4, wherein the polarizing reflector has a property of transmitting light, and the polarizing reflector is disposed with its transmission axis substantially parallel to the transmission axis of the linear polarizer. Reflective element. 6. The selective reflection plate comprises a cholesteric liquid crystal layer that reflects light of a circularly polarized light component around one of the left and right of incident light and transmits light of another polarized light component,
The light reflection element according to claim 4, wherein the reflection wavelength band is a band covering substantially the entire visible light band. 7. A pair of substrates each having electrodes provided on inner surfaces facing each other, and disposed between the pair of substrates, and controls scattering and transmission of incident light according to an electric field applied between the electrodes. A scattering / transmission type liquid crystal element comprising a liquid crystal layer; and a light reflecting element disposed on the back side of the scattering / transmission type liquid crystal element, wherein the light reflecting element is a linear polarizing plate and optically arranged in a thickness direction. A phase plate having an axis, a selective reflection plate that reflects incident light of a predetermined polarization component and transmits incident light of another polarization component, and a back film made of a scattering reflection film or a light absorption film are sequentially laminated from the front side. Light that enters from the front side, passes through the linear polarizer and the phase plate, is reflected by the selective reflection plate, and exits to the front side, or is reflected by the selective reflection plate and faces the front side. Outgoing light and selective reflection Of the light that passes through the plate and is scattered and reflected by the back film made of the scattering reflection film and emitted to the front side, the reflectance for light incident from a direction along the normal to the phase plate is the same as that of the above method. A scattering type liquid crystal display device having an angle selective reflection characteristic smaller than a reflectance for light incident from a direction oblique to a line.