JP2002202524A - Liquid crystal optical element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a display of good contrast even in a reflection mode and a transmission mode with a liquid crystal display element using chiral nematic liquid crystals. SOLUTION: A filter panel 21, polarizing plate 30, λ/4 plate 40, light emitting layer 50 and reflection layer 60 are laminated on the rear surface side of a liquid crystal panel 1. The filter panel 21 is formed by grasping the chiral nematic liquid crystals having a spiral structure of the direction reverse from the torsional direction of the spiral structure of the chiral nematic liquid crystals of the liquid crystal panel 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
Liquid crystal optical element using liquid crystal exhibiting more than one kind of optical stable state, especially in both a transmission mode using light from a light source such as a backlight and a reflection mode not using light from a light source such as a backlight. The present invention relates to a liquid crystal optical element that can be used.

[0002]

2. Description of the Related Art As a liquid crystal used in a liquid crystal display, there is a chiral nematic liquid crystal. The chiral nematic liquid crystal enters a selective reflection state when the optical state (orientation direction) is planar, and enters a fine scattering state and does not exhibit reflection when it is focal conic.

[0003] When a chiral nematic liquid crystal is sandwiched between a pair of parallel substrates, in a planar state, the central axis of a helical twist (referred to as a helical axis) in which the director of the liquid crystal rotates at regular intervals. They are arranged so as to be perpendicular to the substrate on average, and reflect only circularly polarized light corresponding to the direction of the twist. For example, if the direction of the twist is clockwise, only the right circularly polarized light of the selective reflection wavelength is reflected. As described above, by reflecting the light of the specific wavelength, that is, the selective reflection wavelength, of the incident external light, a specific color is observed on the display observation side (side on which the external light is incident).

In the focal conic state, the helical axes of a plurality of liquid crystal domains are arranged in a random direction or a non-perpendicular direction with respect to the substrate. In that state,
Since the chiral nematic liquid crystal is in a non-reflection state, the color of the absorption layer is observed on the display observation side by providing the absorption layer on the substrate on the side opposite to the side where external light is incident. Therefore,
For example, if the color of the absorbing layer is black, the observer can visually recognize the reflection color of the liquid crystal in the selective reflection state and the planar state in contrast to the black display in the non-reflection state of the focal conic state. it can.

When a chiral nematic liquid crystal is changed to a planar state or a focal conic state, a predetermined voltage may be applied to the chiral nematic liquid crystal. In the case of transition from focal conic to planar, a voltage that causes the liquid crystal to be homeotropic is applied, and transition is made to planar via homeotropic. Homeotropic is a liquid crystal orientation in which liquid crystal molecules are substantially parallel to the direction in which an electric field is applied.

The two states (planar and focal conic) are stable even when no electric field is applied, and are bright in the selective reflection state of the planar because a polarizing plate is not required. A liquid crystal optical element using a chiral nematic liquid crystal and utilizing its selective reflection can function as a memory type by maintaining its liquid crystal orientation even when no electric field is applied. Therefore, a liquid crystal optical element with low power consumption can be formed using a chiral nematic liquid crystal. In addition, since display can be performed in the reflection mode without using a light source such as a backlight, power consumption can be reduced in this regard as well.

[0007]

However, in consideration of use in a place with little external light, it is preferable that it can be used in a transmission mode using light from a light source such as a backlight. When a backlight is applied, an absorption layer cannot be provided on the substrate on the side opposite to the display observation side. However, if the backlight is turned on in a state where the absorption layer is not provided, the display state observed on the display observation side becomes a display state with low contrast.

That is, when the portion of the chiral nematic liquid crystal to be turned on is set to the planar state and the portion to be turned off is set to the focal conic state, the portion of the chiral nematic liquid crystal to be turned off is set to the non-reflective state. Therefore, white color is observed on the display observation side. Further, in a portion to be turned on, a color corresponding to a wavelength excluding the selective reflection wavelength, that is, a complementary color of a color according to the wavelength of light from the backlight is observed. When a green light source is used as the backlight, a pale pink color is observed, and the contrast is small with respect to the white in the off-display portion.

As described above, when the liquid crystal display device using the chiral nematic liquid crystal is used in the transmission mode, light is transmitted through both the focal conic state and the planar state, and therefore, the contrast is low. You can only get the display. The contrast in the transmission mode is at most 2 or less.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and can be used in a reflection mode that does not use light from a light source such as a backlight. It is an object of the present invention to provide a liquid crystal optical element capable of obtaining a display with good contrast even in a transmission mode using light from a light source.

[0011]

A liquid crystal optical element according to the present invention is a liquid crystal optical element having a display panel in which a chiral nematic liquid crystal is sandwiched between a pair of substrates, and at least a part of incident light when no light is emitted. A luminescent material that absorbs light, and a chiral nematic liquid crystal having a helical structure in a direction opposite to the twisting direction of the helical structure of the chiral nematic liquid crystal in the display panel between the display panel and the luminescent material. A panel is arranged.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing one embodiment of a liquid crystal optical element according to the present invention. As shown in FIG. 1, a liquid crystal optical element includes a filter panel 21 as a second panel and a polarizing plate (straight line) on a rear surface side (a side opposite to a display observation side) of a liquid crystal panel 1 as a display panel. Polarizing plate) 30,
Phase difference plate (λ / 4 plate) 40, light emitting layer 50, and reflective layer 6
0 is a laminated structure. In the following, the light emitting layer 50
The part constituted by the light emitting element and the reflective layer 60 may be referred to as a lighting element. Further, the polarizing plate 30, the λ / 4 plate 40, and the portion of the lighting element may be collectively referred to as a planar light emitter or a light emitter.

The liquid crystal panel 1 is, as exemplified in FIG.
It has a first substrate 2a and a second substrate 2b. The first substrate 2a is a substrate on the display observation side, and the second substrate 2b is a substrate on the back side. The material of the first substrate 2a and the second substrate 2b is, for example, glass or plastic.

A transparent electrode group 3a is provided on the first substrate 2a, and a transparent electrode group 3b is provided on the second substrate. One of the transparent electrode groups 3a and 3b is a row electrode group, and the other is a column electrode group, which are arranged so as to be substantially orthogonal to each other. Each intersection of the row electrode group and the column electrode group becomes each pixel. In addition,
Only one of the first substrate 2a and the second substrate 2b may be provided with an electrode divided into a plurality of portions, and the other substrate may be provided with one undivided electrode.

On each of the first substrate 2a and the second substrate 2b, an electric insulating layer 4 is formed on the transparent electrode forming surface.
a, 4b are formed. The first substrate 2a and the second substrate 2b on which the transparent electrode groups 3a and 3b and the electric insulating layers 4a and 4b are formed are pressure-bonded via the peripheral sealing material 6. A space surrounded by the first and second substrates 2a and 2b and the peripheral sealing material 6 is filled with a liquid crystal layer 7 of chiral nematic liquid crystal. The liquid crystal layer 7 can exhibit either the planar or focal conic optically stable state even when no voltage is applied.

The filter panel 21 is a panel configured similarly to the liquid crystal panel 1. However, the direction of the twist of the helical structure of the chiral nematic liquid crystal used is opposite to the direction of the twist of the chiral nematic liquid crystal used in the liquid crystal panel 1. The transparent electrodes provided on the upper and lower substrates in the filter panel 21 may be integrated electrodes. That is, the filter panel 21
The chiral nematic liquid crystal is in a focal conic or planar state over the entire surface.

The chiral nematic liquid crystal of the liquid crystal layer 7 in the liquid crystal panel 1 and the chiral nematic liquid crystal used in the filter panel 21 are obtained by mixing a nematic liquid crystal and a chiral agent as an optically active substance. Selectively reflects only circularly polarized light corresponding to the direction. The direction of the twist depends on the optically active substance used.

As the light emitting layer 50, for example, an organic EL can be used. As the reflective layer 60, a mirror sheet, glass or the like on which a metal film or a dielectric multilayer film is deposited, a metal plate, or the like can be used. Also,
An inorganic EL can be used as the light emitting layer 50. When using an inorganic EL, the inorganic EL can also function as the reflection layer 60. That is, the lighting element can be constituted only by the inorganic EL.

FIG. 3 shows the slow axis of the λ / 4 plate 40 and the polarizing plate 5.
It is explanatory drawing which shows the relationship of the direction of the absorption axis of 0. FIG.
As shown in FIG. 3A or FIG. 3B, the polarizing plate 30 disposed between the filter panel 21 and the light-emitting layer 50 has a λ /
The angle between the absorption axis of the polarizing plate 30 and the slow axis of the λ / 4 plate 40 is +45 so that the four plates 40 form a circularly polarizing plate.
Degrees or -45 degrees.

The liquid crystal display device formed as exemplified in FIGS. 1 to 3 is used in both a transmission mode using light from the light emitting layer 50 and a reflection mode not using light from the light emitting layer 50. be able to. Hereinafter, the operation of the liquid crystal display element when used in the transmission mode and when used in the reflection mode will be described. Here, as shown in FIG.
The case where a light source 51 and a light guide plate 52 that guides light from the light source to the λ / 4 plate 40 side is used as the light emitting layer 50 will be described.

As the light source 51, an LED, a cold cathode tube, a hot cathode tube, and other lamps such as a halogen lamp and a metal halide lamp can be used. As the light guide plate 52, a molded product such as a light guide plate having a prism-shaped portion, a light guide plate having a dome-shaped portion, a light guide plate having a blast-shaped portion, or a product printed on the surface of the reflection layer 60 or the like is used. be able to. As the reflective layer 60, a mirror sheet, glass or the like on which a metal film or a dielectric multilayer film is deposited, a metal plate, or the like can be used. Further, it can also be formed by depositing a metal film or a dielectric multilayer film on the light guide plate 52.

FIG. 5 is a cross-sectional view showing an example of the configuration of a lighting element which forms a part of a planar light-emitting body. In the configuration example shown in FIG. 5, an LED unit 51A is used as the light source 51,
As the light guide plate 52, a prism light guide plate 52A is used. The LED unit 51A is, for example, 2 mm × 45 mm
Four green LEDs with an emission wavelength of 530 nm ± 30 nm are mounted on a printed wiring board, and each LED emits 20 mA when turned on.
The voltage is set so that the current flows.

The prism light guide plate 52A has, for example, a size of 45 mm × 55 mm, a thickness of the light incident portion of 2.0 mm and a thickness of the anti-light incident portion of 1.5 mm, and is parallel to the surface on the light incident portion side. A large number of prisms having a triangular cross section are formed. The prism is adjusted so as to emit light at a fixed angle to the anti-prism surface (light emitting surface). Then, the green light from the LED unit 51A is made incident on the light entrance of the prism light guide plate 52A. In addition, as such an illumination element, an element generally used as a backlight of a liquid crystal display can be used.

As the reflection layer 60, for example, a mirror sheet 60A having an average reflectance of 96% and a thickness of 0.1 mm is disposed. Further, in this example, the prism light guide plate 52A
For example, a scattering sheet 70 having a haze of 90%, a total light transmittance of 95%, and a thickness of about 0.1 mm is disposed on the exit surface side of the light emitting element. The scattering sheet 70 is not an essential component, but is effective in making the luminance of the light emitting layer 50 uniform.

Here, the twist direction of the liquid crystal layer 7 of the liquid crystal panel 1 is right, and in the planar state, only the right circularly polarized light is reflected. In the planar state, only left circularly polarized light is reflected. Of course, the twist direction of the liquid crystal layer 7 of the liquid crystal panel 1 may be to the left, and the twist direction of the chiral nematic liquid crystal of the filter panel 21 may be to the right.

First, consider the reflection mode, that is, the state where the LED unit 51A is not lit. LED unit 51A
Is turned off, a predetermined voltage is applied to the chiral nematic liquid crystal of the filter panel 21 to make a focal conic transition. That is, the state of the chiral nematic liquid crystal is changed to a focal conic state on the entire surface of the filter panel 21. In the liquid crystal layer 7 of the liquid crystal panel 1, a portion to which a predetermined voltage for transitioning to the planar state is applied is in the planar state. Also,
A portion to which a predetermined voltage for making a transition to focal conic is applied becomes a focal conic state. Each state is stable even when the applied voltage is erased.

Since the planar state is a state of selective reflection, a color corresponding to the selective reflection wavelength of the liquid crystal layer 7 of the liquid crystal panel 1 is visually recognized on the display observation side. Since the focal conic state is a non-reflective state, almost all external light is transmitted to the filter panel 21 side in the focal conic portion of the liquid crystal layer 7. Since the chiral nematic liquid crystal of the filter panel 21 is in a focal conic state, light transmitted through the liquid crystal panel 1 further transmits through the filter panel 21 and enters the polarizing plate 30. The polarizing plate 30 absorbs one side of the linearly polarized light and emits the other side (the one having a polarization axis different by 90 degrees). The light emitted from the polarizing plate 30 is converted into circularly polarized light by the λ / 4 plate 40, passes through the prism light guide plate 52A, is reflected by the mirror sheet 60A, and enters the λ / 4 plate 40 again.

The circularly polarized light incident on the λ / 4 plate 40 from the mirror sheet 60A is converted into linearly polarized light by the λ / 4 plate 40 and is incident on the polarizing plate 30 again. The direction of the polarization axis of linearly polarized light is
The direction differs from the direction when the light is first emitted from the polarizing plate 30 by 90 degrees. Therefore, the light reflected by the reflective layer 60 is absorbed by the polarizing plate 30. That is, the polarizing plate 30 and the λ / 4 plate 4
0 and the mirror sheet 60A form an absorption layer equivalently. Therefore, of the external light incident from the display observation side, the light transmitted through the focal conic portion of the liquid crystal layer 7 of the liquid crystal panel 1 is formed by the polarizing plate 30, the λ / 4 plate 40, and the reflecting layer 60. It is absorbed by the absorption layer, and when viewed from the display observation side, the portion in the focal conic state is visually recognized as black.

As described above, in the reflection mode, the reflected color based on the selective reflection of the liquid crystal layer 7 of the liquid crystal panel 1 is visually recognized in the planar state, and black in the focal conic state. Therefore, for example, if a voltage is applied so that a portion to be turned on in the liquid crystal panel 1 is in a planar state, a display with good contrast is realized.

Next, a case will be considered where the transmission mode, that is, the LED unit 51A is in a lighting state. When the LED unit 51A is turned on, the filter panel 21
A predetermined voltage for causing a transition to a chiral nematic liquid crystal in a planar state is applied to the entire surface of the substrate. That is, the state of the chiral nematic liquid crystal of the filter panel 21 is a planar state exhibiting selective reflection. Light from the LED unit 51A is transmitted through the prism light guide plate 52A to λ.
The light passes through the / 4 plate 40 and enters the polarizing plate 30. Polarizing plate 3
0 absorbs one side of the linearly polarized light and emits the other side.
Light emitted from the polarizing plate 30 is converted into circularly polarized light by the λ / 4 plate 40 and enters the filter panel 21.

The chiral nematic liquid crystal of the filter panel 21 is in a planar state. In the chiral nematic liquid crystal of the filter panel 21, the twist direction is left. Therefore, the filter panel 21 reflects most of the left circularly polarized light among the incident circularly polarized light and transmits the right circularly polarized light.

In a portion of the liquid crystal layer 7 of the liquid crystal panel 1 which is in a focal conic state, right circularly polarized light from the filter panel 21 side is transmitted. Further, since the twist direction of the chiral nematic liquid crystal used for the liquid crystal layer 7 of the liquid crystal panel 1 is rightward, the portion in the planar state almost reflects right circularly polarized light from the filter panel 21 side. . Therefore, in the transmission mode, the portion in the planar state in the liquid crystal layer 7 of the liquid crystal panel 1 hardly leaks light from the LED unit 51A to the display observation side, and is viewed as black when viewed from the display observation side. The part in the focal conic state is L
The emission color from the ED unit 51A is visually recognized. As a result, a display with good contrast can be obtained.

As described above, in this embodiment, the filter panel 21 and the polarizing plate 3
In the reflection mode, most of the light that is not selectively reflected by the liquid crystal layer 7 of the liquid crystal panel 1 is absorbed on the back surface of the liquid crystal panel 1. Therefore, almost the same display as when the black absorbing layer is actually provided on the back surface of the liquid crystal panel 1 can be obtained.

In the transmission mode, the filter panel 2
By making the state of the chiral nematic liquid crystal 1 planar, only the circularly polarized light of the direction selectively reflected by the liquid crystal layer 7 out of the left and right circularly polarized light from the rear side of the liquid crystal panel 1 is incident thereon. In 7, almost no light leaks from the planar portion. Also,
In a portion of the liquid crystal layer 7 of the liquid crystal panel 1 which is in a focal conic state, light from the filter panel 21 is almost transmitted. As a result, a display with good contrast in which the negative / positive is reversed from that in the reflection mode can be obtained. Therefore, with the configuration as in this embodiment, a display with good contrast is realized in both the reflection mode and the transmission mode.

In the emission spectrum of the lighting element, the emission center wavelength (λ _rad ) matches the selective reflection center wavelength (λ _refl ) of the liquid crystal layer 7 of the liquid crystal panel 1, and the emission spectrum half width (Δλ _rad ) has the selective reflection spectrum. Half width (Δλ
_refl ) is most preferably less than Δλ _rad
If <Δλ _refl , | λ _rad −λ _refl | <
Even about 100 nm can be used. Also, | λ
It is more preferable that _rad− λ _refl | <50 nm.

When Δλ _rad ≧ Δλ _refl , Δ
It is preferable that λ _rad −Δλ _refl <100 nm.

It is most preferable that the center wavelength of the selective reflection of the chiral nematic liquid crystal of the filter panel 21 coincides with the center wavelength of the selective reflection of the liquid crystal layer 7 of the liquid crystal panel 1 (λ _refl ). When the 21 central wavelength of the chiral nematic liquid crystal of selective reflection of the _{(λ fil), | λ refl} -λ fil | <1
It is preferably about 00 nm.

In the above description, the electrodes provided on the upper and lower substrates of the filter panel 21 have an integral structure, and the chiral nematic liquid crystal is in a focal conic or planar state over the entire surface of the filter panel 21. However, a part of the chiral nematic liquid crystal of the filter panel 21 is in a focal conic state when the light emitter is not emitting light, and a part of the chiral nematic liquid crystal of the filter panel 21 is in the planar state when the light emitter is emitting light. Good. For example, by arranging patterned electrodes to provide a display with high contrast only in a specific portion, or by arranging electrodes in a fine pattern such as a stripe pattern to control the area of each state (focal conic or planar state). The contrast of the entire screen may be adjusted.

The structure of the electrodes provided on the upper and lower substrates in the filter panel 21 is the same as the structure of the electrodes in the liquid crystal panel 1, and the filter panel is operated in the same state as the voltage applied state corresponding to the display state of the liquid crystal panel 1. A voltage may be applied to 21. That is, the liquid crystal panel 1 and the filter panel 21 may be configured to display the same display data.

In such a configuration, a part of the liquid crystal panel 1 corresponding to the part in the planar state in the filter panel 21 is also in the planar state. Then, in the reflection mode, the liquid crystal panel 1
Since both left and right circularly polarized light are reflected by the filter panel 21 and the filter panel 21, that portion (the portion in a planar state)
Brightness can be further improved. That is, the liquid crystal panel 1 and the filter panel 21 realize a two-layer helical structure in which the directions of the twists of the helical structure are different from each other. Since selective reflection is performed in each of the two layers, the brightness of the reflective display is greatly improved. Can be done.

In the transmission mode, the portion of the filter panel 21 corresponding to the portion of the liquid crystal panel 1 which is in the focal conic state is also in the state of focal conic, so that the entire surface of the filter panel 21 is planar as described above. Part of the light from the illuminant side is not reflected by the filter panel 21 as in the case of the state described above, and the brightness of that part (the part in the focal conic state) is further improved. Can be.

Next, a method of manufacturing the liquid crystal panel 1 and the filter panel 21 will be described. In manufacturing the liquid crystal panel 1, a polyimide thin film is formed by spinner coating on surfaces of two glass substrates having transparent electrodes in contact with the liquid crystal layer 7, and thereafter, resin spacers having a diameter of 4 μm are sprayed on upper and lower substrate surfaces. Epoxy resin was printed on the four sides with the same diameter except for the injection hole, and the upper and lower substrates were bonded to form a cell. This is called an empty cell. The transparent electrode arranged on one glass substrate is a common electrode over the entire surface,
The transparent electrode arranged on the other glass substrate is an electrode corresponding to the pattern to be displayed.

As a chiral nematic liquid crystal, Tc = 8
7 ° C., Δn = 0.231, Δε = 16.5, viscosity η =
44.7 parts of a nematic liquid crystal having a specific resistance of 2 × 10 ¹¹ Ω · cm at 32 mPa · s and a chiral agent represented by Chemical Formula 1
A liquid crystal is used in which 1 part, 5.1 parts of the chiral agent shown in (Chemical Formula 2) and 5.1 parts of the chiral agent shown in (Chemical Formula 3) are dissolved and mixed.
The helical pitch of this liquid crystal is about 0.34 μm. The chiral nematic liquid crystal thus adjusted is hereinafter referred to as liquid crystal A.

[0045]

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[0046]

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[0047]

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After the liquid crystal A was injected into the empty cell by a vacuum injection method, the injection port was sealed with an ultraviolet curable resin to produce a liquid crystal panel 1. The peak wavelength of the selective reflection of the liquid crystal panel 1 was about 530 nm. The liquid crystal A using the chiral agent shown in [Chemical Formula 1] to [Chemical Formula 3] has a right-handed twist direction,
The liquid crystal panel 1 using the liquid crystal A reflects right circularly polarized light and transmits left circularly polarized light in the planar state.

When the filter panel 21 is manufactured,
As a chiral nematic liquid crystal, Tc = 87 ° C., Δn
= 0.231, Δε = 16.5, viscosity η = 32 mPa ·
s, nematic liquid crystal 8 having a specific resistance of 2 × 10 ¹¹ Ω · cm
A liquid crystal obtained by dissolving and mixing 5.1 parts of the chiral agent shown in Chemical Formula 4, 5.1 parts of the chiral agent shown in Chemical Formula 5, and 5.1 parts of the chiral agent 5.1 shown in Chemical Formula 6 in 4.7 parts. Used. The helical pitch of this liquid crystal is about 0.34 μm. The chiral nematic liquid crystal thus adjusted is hereinafter referred to as liquid crystal B.

[0050]

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[0051]

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[0052]

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The liquid crystal B using the chiral agent shown in [Chemical Formula 4] to [Chemical Formula 6] has a left-handed twist direction, and the filter panel 21 using the liquid crystal B reflects left circularly polarized light in the planar state. And right circularly polarized light.

Liquid crystal B corresponds to liquid crystal A in which the same nematic liquid crystal and a chiral agent having the same molecular structure and different optical activities are combined. The liquid crystal A and the liquid crystal B may be manufactured using chiral agents having different molecular structures. However, as in the above-described manufacturing method, the liquid crystal panel 1 and the filter panel 21 are formed using liquid crystals using chiral agents having the same molecular structure. It is easy to match the center wavelengths and the like of the selective reflection of both if the above is manufactured.

Furthermore, in the above-described manufacturing method, the liquid crystal A and the liquid crystal B use the same chiral agent having the same molecular structure and the same ratio between the nematic liquid crystal and the chiral agent. The center wavelength of reflection and the center wavelength of selective reflection of the filter panel 21 can be easily matched.

As described above, in the above embodiment, the filter panel 21 and the polarizing plate 3 are provided on the back surface of the liquid crystal panel 1 having the liquid crystal layer 7 made of chiral nematic liquid crystal.
The 0, λ / 4 plate 40, the lighting element, and the reflection layer 60 are arranged, and the twist direction of the chiral nematic liquid crystal of the filter panel 21 is opposite to the twist direction of the liquid crystal layer 7 in the liquid crystal panel 1. With such a configuration, in the reflection mode, all or part of the light not selectively reflected by the liquid crystal panel 1 is absorbed on the side opposite to the display observation side. In the transmission mode, all or part of both left and right circularly polarized light from the light emitter can be selectively reflected by the filter panel 21 and the liquid crystal panel 1. As a result, a display with good contrast can be obtained in both the transmission mode and the reflection mode.

[0057]

According to the present invention, a liquid crystal display device is provided with a luminous body that absorbs at least a part of incident light when no light is emitted, and a chiral nematic liquid crystal in the display panel is provided between the display panel and the luminous body. Since the second panel sandwiching a chiral nematic liquid crystal having a helical structure in the direction opposite to the twisting direction of the helical structure is arranged, high-contrast display can be realized in both the reflection mode and the transmission mode. This has the effect of obtaining a liquid crystal display device that can be operated.

[Brief description of the drawings]

FIG. 1 is a schematic view showing one embodiment of a liquid crystal optical element.

FIG. 2 is a cross-sectional view illustrating a configuration example of a liquid crystal panel.

FIG. 3 is an explanatory diagram showing the relationship between the direction of the slow axis of the λ / 4 plate and the direction of the absorption axis of the polarizing plate.

FIG. 4 is a schematic view showing a liquid crystal optical element using a light source and a light emitting layer formed of a light guide plate.

FIG. 5 is a cross-sectional view illustrating a configuration example of a lighting element.

[Explanation of symbols]

 Reference Signs List 1 liquid crystal panel 21 filter panel 30 polarizing plate 40 retardation plate (λ / 4 plate) 50 light emitting layer 51 light source 51A LED unit 52 light guide plate 52A prism light guide plate 60 reflection layer 60A mirror sheet

Continued on the front page (72) Inventor Shinya Tahara 1150 Hazawa-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Inside Asahi Glass Co., Ltd. F term (reference) 2H088 GA02 GA08 GA12 GA17 MA02 MA20 2H089 HA21 KA20 QA16 5C094 AA01 BA03 BA43 CA19 JA11

Claims (5)

[Claims] 1. A liquid crystal optical element comprising a display panel in which a chiral nematic liquid crystal is sandwiched between a pair of substrates,
A luminous body that absorbs at least a part of incident light when not emitting light, and a helix having a direction opposite to a twist direction of a helical structure of the chiral nematic liquid crystal in the display panel between the display panel and the luminous body. A liquid crystal optical element comprising a second panel sandwiching a chiral nematic liquid crystal having a structure. 2. The center wavelength of selective reflection of a chiral nematic liquid crystal of a display panel and the center wavelength of selective reflection of a chiral nematic liquid crystal of a second panel.
The liquid crystal optical element according to the above. 3. The center wavelength of the selective reflection of the chiral nematic liquid crystal of the display panel is λ _refl, and the center wavelength of the selective reflection of the chiral nematic liquid crystal of the second panel is λ _refl.
If | _fil |, | _λrefl-λfil | <100n
The liquid crystal optical element according to claim 1, wherein m is m. 4. When the luminous body does not emit light, a part or the whole of the chiral nematic liquid crystal of the second panel is in a focal conic state, and when the luminous body emits light, a part or the whole of the chiral nematic liquid crystal is in a planar state. The liquid crystal optical element according to any one of claims 1 to 3, wherein 5. The liquid crystal optical element according to claim 1, wherein the display panel and the second panel have the same electrode structure and display the same display data.