JP2002049038A - Reflection type liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display device in which uniform display quality in the display region is realized. SOLUTION: The device has a liquid crystal layer 30 which selectively reflects light in a specified wavelength region, a pair of alignment layers 16 and 26 formed on both surfaces of the liquid crystal layer, and a pair of electrodes 14 and 24 to apply voltage on the liquid crystal layer 30. One of the alignment layers 16 and 26 is a horizontal alignment layer 16 and the other is a perpendicular alignment layer 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection type liquid crystal display device which performs display by reflecting external light, and more particularly to a reflection type liquid crystal display device having a liquid crystal layer which selectively reflects light in a specific wavelength region. The present invention relates to a reflection type liquid crystal display device.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been characterized by their thinness and low power consumption, and have been developed to use OA equipment such as word processors and personal computers, portable information equipment such as electronic notebooks, and cameras equipped with liquid crystal monitors. Widely used for body VTRs and the like.

A liquid crystal display device is not a self-luminous display device that emits light by itself, unlike a CRT (cathode ray tube) or EL (electroluminescence).
In the case of a transmissive liquid crystal display device using a pixel electrode (transparent electrode) formed of a transparent conductive material such as (Indium Tin Oxide), a lighting device (a so-called backlight) such as a fluorescent tube is disposed behind the liquid crystal panel. do it,
The display is performed by the light incident from there.

[0004] In the case of a transmissive liquid crystal display device, display is performed using a backlight as described above. Therefore, in order to reduce the size and weight of various devices using the liquid crystal display device, it is necessary to provide a backlight. Space and backlight weight are a problem. In addition, since the backlight consumes 50% or more of the total power consumption of the liquid crystal display device, the power consumption increases, and when it is used for a portable device,
A large (large capacity) battery is required, which is another factor that hinders miniaturization and weight reduction. Further, when the ambient light is much brighter than the display light, such as when the device is used outdoors under fine weather, there is a problem that the contrast ratio is greatly reduced.

On the other hand, in the case of a reflection type liquid crystal display device which performs display by reflecting externally incident light,
Since there is no need to provide a backlight and a small battery can be used, there is an advantage that further reduction in size and weight can be achieved. Further, since the amount of display light corresponding to the amount of ambient light is obtained, the contrast ratio does not decrease even when used outdoors under fine weather. Therefore, the reflective liquid crystal display device can be suitably used for portable information terminals, digital cameras, portable video cameras, and the like.

However, although having many advantages as described above, the reflection type liquid crystal display devices currently in practical use have a low reflectance (ratio of reflected light intensity to incident light intensity) and have low ambient light. Has a problem that the visibility is extremely reduced when is relatively dark.

[0007] The main reason for the low reflectivity is that the reflective liquid crystal display devices currently in practical use use either one or two polarizers in any system. That is, 50% or more of incident light is absorbed by these polarizers and is lost without being used for display.

Therefore, as a reflection type liquid crystal display device using no polarizer, a reflection type liquid crystal display provided with a liquid crystal layer (a liquid crystal layer having a helical structure such as a cholesteric liquid crystal layer) that selectively reflects light in the visible light region. An apparatus has been proposed (for example, JP-A-7-209662).

The phenomenon that the cholesteric liquid crystal layer selectively reflects light having a wavelength corresponding to the helical pitch is, for example, as follows.
Appl. Opt. Vol. 7, No. 9, page 1729 (1968)
Year), Phys. Rev .. Vol. 5, No. 9, pp. 577 (19
70 years).

For example, a right-handed cholesteric liquid crystal layer selectively reflects only clockwise circularly polarized light (right circularly polarized light) having a wavelength λ in the range of no · p <λ <ne · p. Right-handed circularly polarized light of a wavelength and left-handed circularly polarized light of all wavelengths (left circularly polarized light) are transmitted. Here, no and ne are the refractive indexes of the liquid crystal layer with respect to ordinary light and extraordinary light, p is a helical pitch, and λ is a reflection wavelength. The reflection center wavelength λm at this time is λm, where na is the average refractive index of the liquid crystal layer.
= Na · p. On the other hand, the left-handed cholesteric liquid crystal layer selectively reflects only counterclockwise circularly polarized light in a specific wavelength region, contrary to the above-described right-handed cholesteric liquid crystal layer.

As a liquid crystal layer having such an effect of selectively reflecting light in a specific wavelength region (selective reflection effect), in addition to the cholesteric liquid crystal layer already described, an optical material that is optically added to a normal nematic liquid crystal material can be used. Examples include a chiral nematic liquid crystal layer to which an active chiral agent is added, a chiral smectic liquid crystal layer, and the like. The cholesteric liquid crystal layer is generally unstable and unreliable to stimuli caused by the atmosphere or ultraviolet rays, while the chiral nematic liquid crystal layer is excellent in light resistance and stable, and the helical pitch can be adjusted relatively. A chiral nematic liquid crystal layer is generally used for practical use because it is easy, the reflection wavelength width can be easily adjusted, and the range of material selection is wide.

The presently proposed reflective liquid crystal display devices having the above-mentioned liquid crystal layer, for example, the reflective liquid crystal display devices disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 7-209662, etc. It has a configuration in which a horizontal alignment layer is provided on the surfaces of two substrates sandwiching a liquid crystal layer, that is, a configuration in which a horizontal alignment layer is provided on both surfaces of a liquid crystal layer.

[0013]

However, the inventors of the present invention have made a prototype of a reflective liquid crystal display device having a horizontal alignment layer provided on both sides of a liquid crystal layer and evaluated its spectral characteristics. It has been found that there are regions where different wavelength regions are present, resulting in non-uniform display, which causes display unevenness and alignment defects observed as disclination lines.

The inventor of the present invention similarly evaluated the spectral characteristics of a reflection type liquid crystal display device in which vertical alignment layers were provided on both surfaces of a liquid crystal layer. As a result, in this case, selective reflection occurs in the display area. There are regions with different wavelength regions,
It has been found that there is a problem in that the display becomes uneven and display unevenness occurs, and the wavelength region for selective reflection is widened, thereby lowering color purity.

[0015] SID98.p109 (1998)
Is a numerical analysis of the relaxation process of a liquid crystal layer sandwiched between a pair of substrates from homeotropic alignment (when an electric field is applied in the direction normal to the substrate) to planar alignment (when no electric field is applied). The results are described for the case where it is assumed that the substrate has a horizontal alignment regulating force and the case where both surfaces of the substrate are assumed to have a vertical alignment regulating force, but the display characteristics are not mentioned.

The present invention has been made in view of the above points, and an object of the present invention is to provide a reflection type liquid crystal display device in which uniform display quality is realized in a display area.

[0017]

According to the present invention, there is provided a reflective liquid crystal display device comprising at least one liquid crystal layer for selectively reflecting light in a specific wavelength region, and both surfaces of the at least one liquid crystal layer. A pair of alignment layers;
At least one pair of electrodes for applying a voltage to one liquid crystal layer, one of the pair of alignment layers is a horizontal alignment layer, and the other is a vertical alignment layer. The above object is achieved.

The horizontal alignment layer may be provided on a surface of the at least one liquid crystal layer on the viewer side.

Alternatively, the vertical alignment layer may be provided on a surface of the at least one liquid crystal layer on the viewer side.

Preferably, the thickness of the at least one liquid crystal layer is defined by a columnar spacer formed on a substrate provided on the side of the at least one liquid crystal layer on the side of the vertical alignment layer.

The at least one liquid crystal layer is two liquid crystal layers stacked on each other via a dielectric sheet, and the at least one pair of electrodes are opposed to each other via the two liquid crystal layers and the dielectric sheet. One of the two liquid crystal layers selectively reflects right circular knitted light of a specific first wavelength region, and the other of the two liquid crystal layers has a left side of a specific second wavelength region. It is preferable to adopt a configuration in which circularly polarized light is selectively reflected.

Of the two liquid crystal layers, the horizontal alignment layer is provided on a viewer side surface of one of the liquid crystal layers, and the vertical alignment layer is provided on a viewer side surface of the other liquid crystal layer. Is preferred.

Alternatively, the horizontal alignment layer or the vertical alignment layer may be provided on the observer side of each of the two liquid crystal layers.

The vertical alignment layer is provided on a surface of each of the two liquid crystal layers on the side of the dielectric sheet, and the thickness of each of the two liquid crystal layers is different from that of each of the two liquid crystal layers. It is preferable to adopt a configuration defined by a columnar spacer formed on a substrate provided so as to face the dielectric sheet with the interposition therebetween.

Hereinafter, the operation of the present invention will be described.

In the reflection type liquid crystal display device of the present invention,
Since one of the pair of alignment layers provided on both surfaces of the liquid crystal layer is a horizontal alignment layer, the liquid crystal molecules of the liquid crystal layer are horizontally aligned with the horizontal alignment layer on the surface of the horizontal alignment layer.
Therefore, the helical axis of the helical structure of the liquid crystal layer that selectively reflects light in a specific wavelength region is maintained perpendicular to the horizontal alignment layer. As a result, a decrease in the color purity of the selectively reflected light is suppressed, and a change in the wavelength region of the selectively reflected light is suppressed.

Further, since the other is a vertical alignment layer, the liquid crystal molecules of the liquid crystal layer do not receive the alignment control force in the azimuthal direction on the surface of the vertical alignment layer. Therefore, even if the thickness (cell gap) of the liquid crystal layer changes in the display area, the number of spiral turns of the spiral structure of the liquid crystal layer continuously changes, and the spiral pitch does not change. As a result, the generation of alignment defects is suppressed, and the change in the wavelength region of the selectively reflected light is suppressed.

According to the present invention, as described above, it is possible to improve the uniformity of the spectral characteristics in the display area.

When a horizontal alignment layer is provided on the surface of the liquid crystal layer on the viewer side, the liquid crystal molecules in the vicinity of the viewer side of the liquid crystal layer have uniform planar alignment, and the reflection surface has metallic luster. . As a result, a display that is very bright in a specific viewing angle range and has high color purity is realized.

When a vertical alignment layer is provided on the viewer side of the liquid crystal layer, liquid crystal molecules near the viewer side of the liquid crystal layer are not in planar alignment, and the reflection surface is slightly scattered. Take on the nature. As a result, a display with good visibility is realized in a wide viewing angle range.

If a structure in which the thickness of the liquid crystal layer is defined by the columnar spacer formed on the substrate provided on the side of the liquid crystal layer on the vertical alignment layer is adopted, the liquid crystal layer is formed on the substrate with relatively high positional accuracy. Since the thickness of the liquid crystal layer is defined by the columnar spacers that can be formed, by forming the columnar spacers in portions other than the picture element regions that do not contribute to display,
It is possible to improve the aperture ratio and reduce the influence of the orientation of the liquid crystal molecules in the vicinity of the columnar spacer on the display. Further, since the columnar spacer is formed on the substrate provided on the vertical alignment layer side, it is not necessary to perform a rubbing process on the substrate on which the columnar spacer is formed in a manufacturing process. Therefore, the defect of the columnar spacer is prevented, and the alignment defect due to the rubbing shadow caused by the columnar spacer does not occur.

The two layers stacked on each other via a dielectric sheet
One of the two liquid crystal layers selectively reflects right circular knitted light in a specific first wavelength region and the other selectively reflects left circularly polarized light in a specific second wavelength region. When a configuration that reflects light is adopted, one liquid crystal layer selectively reflects right circular knitted light in a specific first wavelength region, and the other liquid crystal layer reflects left circularly polarized light in a specific second wavelength region. Both right-handed circularly polarized light and left-handed circularly polarized light included in the incident light can be used for display, and a very bright display is realized. The specific first wavelength region and the specific second wavelength region may be the same wavelength region with each other, may be different wavelength regions from each other, may partially overlap with each other, or one may be the other. May be included. In addition, since the two liquid crystal layers are stacked via the dielectric sheet, there is no parallax which is a problem in the configuration via the substrate.

At this time, of the two liquid crystal layers, a horizontal alignment layer is provided on the viewer side surface of one of the liquid crystal layers, and a vertical alignment layer is provided on the viewer side surface of the other liquid crystal layer. Of the right circularly polarized light and the left circularly polarized light included in the incident light, one of the circularly polarized light is reflected by the liquid crystal layer in which liquid crystal molecules near the surface on the observer side have a uniform planar orientation. On the other hand, the other circularly polarized light is reflected by a liquid crystal layer in which liquid crystal molecules in the vicinity of the observer side are not in planar alignment. As a result, very bright and high color purity is achieved in a specific viewing angle range, and display with good visibility is realized in a wide viewing angle range.

When a horizontal alignment layer is provided on each of the two liquid crystal layers on the surface on the observer side, both the right circularly polarized light and the left circularly polarized light contained in the incident light are on the observer side. Are reflected by the liquid crystal layer having a uniform planar orientation. As a result, a display that is very bright and has high color purity in a specific viewing angle range is realized.

Alternatively, if a vertical alignment layer is provided on the surface of each of the two liquid crystal layers on the viewer side, both the right circularly polarized light and the left circularly polarized light contained in the incident light are changed on the viewer side. Are reflected by the liquid crystal layer that is not in the planar alignment. As a result, a display with good visibility is realized in a wide viewing angle range.

A vertical alignment layer is provided on the surface of each of the two liquid crystal layers on the side of the dielectric sheet, and the thickness of each of the two liquid crystal layers is adjusted to the dielectric sheet via each of the two liquid crystal layers. When the configuration defined by the columnar spacers formed on the substrates provided so as to face each other is adopted, the vertical alignment layers are provided on the surfaces of the two liquid crystal layers on the side of the dielectric sheet. In the process, the stress when rubbing the horizontal alignment layer is not applied to the dielectric sheet. As a result, the strength reliability is increased.
In addition, since the stress does not reach the dielectric sheet, a relatively thin dielectric sheet can be used. As a result, the parallax can be further reduced and the driving voltage can be reduced. Further, since the thickness of the two liquid crystal layers is defined by the columnar spacers that can be formed on the substrate with relatively high positional accuracy, the columnar spacers are formed on the two substrates so as to face each other. , Supporting the dielectric sheet so as to sandwich it from above and below,
The thickness (cell gap) of the liquid crystal layer can be defined with high accuracy. In addition, since the dielectric sheet can be supported so as to be sandwiched from above and below, a relatively thin dielectric sheet can be used. As a result, the parallax can be further reduced and the driving voltage can be reduced. it can. Further, by forming the columnar spacer in a portion other than the picture element region that does not contribute to display, it is possible to improve the aperture ratio and to reduce the influence of the orientation of the liquid crystal molecules near the columnar spacer on the display. It becomes possible.

[0037]

DESCRIPTION OF THE PREFERRED EMBODIMENTS To solve the above-mentioned problems, the present inventor has proposed a reflection type liquid crystal display device having a horizontal alignment layer on both sides of a liquid crystal layer and a reflection type liquid crystal display having a vertical alignment layer on both sides of the liquid crystal layer. A prototype liquid crystal display device was prototyped, its spectral characteristics were evaluated, and detailed studies were conducted. As a result, the following findings were obtained.

First, a case where a horizontal alignment layer is provided on both surfaces (upper surface and lower surface) of a liquid crystal layer will be described. in this case,
The liquid crystal molecules of the liquid crystal layer are horizontally aligned with respect to the substrate on the upper and lower surfaces of the horizontal alignment layer, so that the helical axis of the helical structure of the liquid crystal layer is perpendicular to the substrate. Also,
The liquid crystal molecules near the upper and lower surfaces of the liquid crystal layer are oriented in a specific azimuthal direction according to the alignment regulating force of each horizontal alignment layer. The direction of the alignment regulating force of the horizontal alignment layer is generally defined by a rubbing process.

Usually, there is some variation in the cell gap (the thickness of the liquid crystal layer) in the display area.
As described above, the liquid crystal molecules in the vicinity of the upper surface and the lower surface of the liquid crystal layer are each subjected to an alignment regulating force such that they are aligned in a specific azimuthal direction. The direction does not change. For this reason, the number of spiral turns of the spiral structure of the liquid crystal layer cannot be changed continuously. On the other hand, the local orientation direction of the liquid crystal molecules in the liquid crystal layer having a helical structure is matched each time the helix makes a half turn. Therefore, the number of spiral turns is discontinuously increased by 0.5 with the change of the cell gap.
(Half turn).

Therefore, if there is a cell gap variation exceeding about half the helical pitch in the display area, a plurality of areas in which the number of helical turns of the liquid crystal layer is different by 0.5 (half turn). Will be present. It is considered that, at the boundary between the regions having different helical rotation numbers, the alignment state of the liquid crystal molecules changes discontinuously, so that an alignment defect was generated, and this was observed as a disclination line.

In a region where the change of the cell gap does not exceed about half of the helical pitch, the number of spiral turns does not change. Therefore, as the cell gap increases, the helical pitch becomes longer and longer, and as the cell gap becomes smaller. The helical pitch is reduced and shortened. Therefore, in the region where the number of spiral turns is the same, there are regions where the spiral pitch is different. Since the wavelength region to be selectively reflected depends on the helical pitch, it is considered that there is a region in the display region where the wavelength region to be selectively reflected is different, resulting in non-uniform display and display unevenness.

Next, a case where a vertical alignment layer is provided on both surfaces (upper and lower surfaces) of the liquid crystal layer will be described. In this case, the liquid crystal molecules of the liquid crystal layer do not receive an alignment regulating force such that they are aligned in a specific azimuthal direction on the surfaces of the vertical alignment layers on the upper surface and the lower surface. The numbers are expected to change continuously. Therefore,
It is considered that the change in the helical pitch and the alignment defect that occur when the horizontal alignment layers are provided on both surfaces do not occur in this case.

However, on the surface of the vertical alignment layer, the liquid crystal molecules of the liquid crystal layer are subjected to an alignment regulating force such that the liquid crystal molecules are aligned perpendicular to the substrate, so that the helical axis of the helical structure is not perpendicular to the substrate. Tilt randomly. Therefore, the inclination of the helical axis of the helical structure of the liquid crystal layer with respect to the substrate in the display region is not uniform. Therefore, it is considered that there are regions where the wavelength regions to be selectively reflected are different from each other, resulting in non-uniform display and display unevenness, and the wavelength region to be selectively reflected is widened, thereby causing a decrease in color purity.

The present invention has been made based on the above findings obtained by the present inventors. Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings. Note that the present invention is not limited to the following embodiments. (Embodiment 1) FIG. 1 schematically shows a reflection type liquid crystal display device 100 according to Embodiment 1 of the present invention.

The reflection type liquid crystal display device 100 includes a liquid crystal layer 30 for selectively reflecting light in a specific wavelength region, a pair of alignment layers 16 and 26 provided on both sides of the liquid crystal layer, and a voltage applied to the liquid crystal layer 30. And a pair of alignment layers 16 and 26, one of which is a horizontal alignment layer 16 and the other is a vertical alignment layer 26.

More specifically, a liquid crystal layer 30 for selectively reflecting light in a specific wavelength region is provided between the first substrate 10 and the second substrate 20, and the first substrate 10 is a transparent substrate. 12, a transparent electrode 14 formed on the surface of the transparent substrate 12 on the liquid crystal layer 30 side, and a horizontal alignment layer 16 formed on the transparent electrode 14.
A light absorbing layer 23 formed on the surface of the transparent substrate 22 on the liquid crystal layer 30 side to absorb light in the visible light region; a transparent electrode 24 formed on the light absorbing layer 23; Vertical alignment layer 26.

The method of manufacturing the above-mentioned reflection type liquid crystal display device 100 will be specifically described below.

The first substrate 10 is manufactured, for example, as follows. First, a transparent electrode 14 made of an ITO layer is formed on the surface of the transparent substrate 12 made of glass or the like on the liquid crystal layer 30 side to a thickness of about 100 nm by a sputtering method. Next, a horizontal alignment layer 16 is formed on the transparent electrode 14 so as to have a thickness of about 50 nm. Horizontal alignment layer 16
For example, first, AL4552 manufactured by JSR is applied by spin coating, and then baked at about 180 ° C. for about 60 minutes.
Thereafter, it is obtained by applying an alignment regulating force for aligning the liquid crystal molecules in a specific azimuthal direction by rubbing treatment.

On the other hand, the second substrate 20 is manufactured, for example, as follows. First, a light absorbing layer 23 for absorbing light in the visible light region is formed on the surface of the transparent substrate 22 made of glass or the like on the liquid crystal layer 30 side using, for example, vinyl chloride.
The light absorbing layer 23 may be provided outside the transparent substrate 22 (on the side other than the liquid crystal layer 30 side). Next, a transparent electrode 24 made of an ITO layer is formed on the light absorbing layer 23 by a sputtering method so as to have a thickness of about 100 nm. Thereafter, a vertical alignment layer 26 is formed on the transparent electrode 24 so as to have a thickness of about 50 nm. Vertical alignment layer 2
6 is, for example, N, N-dimethyl-N-octadecyl-
3-aminopropyltrimethoxylyl chloride (N, N-dimethyl-N-octadecyl)
-3-aminopropritrimethyoxys
il chloride) is applied by a dip method, and then baked at about 120 ° C. for about 30 minutes.

The first substrate 10 and the second substrate 20 manufactured as described above are bonded so that the cell gap is about 5 μm. Then, the bonded first substrate 10
A liquid crystal material is injected into the gap between the substrate and the second substrate 20 to form a liquid crystal layer 30. As a material of the liquid crystal layer 30, for example,
A chiral nematic liquid crystal material is used in which a chiral agent S811 (manufactured by Merck) is mixed at about 21.7 wt% with a nematic liquid crystal material ZLI4792 (manufactured by Merck) so that the spontaneous pitch of the spiral structure is about 0.4 μm. The chiral nematic liquid crystal layer 30 has a left-handed helical structure, selectively reflects left-handed circularly polarized light in a wavelength region having a center wavelength of about 620 nm, and exhibits red. Reference numeral 32 in FIG. 1 denotes a chiral nematic liquid crystal layer 30.
Is schematically shown.

As the configuration and the driving method of the transparent electrodes 14 and 24 for driving the liquid crystal layer 30, the known electrode configuration and the driving method can be used. For example,
An active matrix type, a simple matrix type, or a segment type can be used.

The reflection type liquid crystal display device 100 thus obtained performs display as follows. First, when no voltage is applied, of the incident light, counterclockwise circularly polarized light in a wavelength region having a center wavelength of about 620 nm is selectively reflected by the liquid crystal layer 30 and counterclockwise circularly polarized light other than the above wavelength region. And right-handed circularly polarized light in all wavelength regions passes through the liquid crystal layer 30 and is absorbed by the light absorbing layer 23.
A color corresponding to a wavelength region having a center wavelength of 0 nm, that is, red is displayed. Next, when a voltage is applied, the helical structure of the liquid crystal layer 30 is broken, so that all incident light is
And is absorbed by the light absorbing layer 23, so that black is displayed. In this way, two-color display of red / black is performed.

In this embodiment, the case where the light absorbing layer 23 for absorbing light in the visible light region is used has been described. However, the present invention is not limited to this. For example, light in the wavelength region corresponding to green is reflected. Alternatively, a light absorbing layer that absorbs light in the other visible light region may be used. In this case, when a voltage is applied, light in a wavelength region corresponding to green is reflected by the light absorbing layer, and green is displayed. On the other hand, when no voltage is applied, light in the wavelength region corresponding to green is reflected by the light absorbing layer, and light in the wavelength region corresponding to red is reflected by the liquid crystal layer 30, so that yellow (orange) is displayed. You. In this way, a two-color display of yellow (orange) / green is possible.

In the reflection type liquid crystal display device 100 according to the present invention, one of the pair of alignment layers 16 and 26 provided on both surfaces of the liquid crystal layer 30 is the horizontal alignment layer 16. In this case, the liquid crystal molecules of the liquid crystal layer 30 are horizontally aligned with the horizontal alignment layer 16. Therefore, the helical axis of the helical structure of the liquid crystal layer 30 is maintained perpendicular to the horizontal alignment layer 16. As a result, a decrease in the color purity of the selectively reflected light is suppressed, and a change in the wavelength region of the selectively reflected light is suppressed.

Since the other is the vertical alignment layer 26,
On the surface of the vertical alignment layer 26, the liquid crystal molecules of the liquid crystal layer 30 do not receive the alignment control force in the azimuthal direction. Therefore, even if the thickness (cell gap) of the liquid crystal layer 30 changes in the display area, the number of spiral turns changes continuously, and the spiral pitch does not change. As a result, the generation of alignment defects is suppressed, and the change in the wavelength region of the selectively reflected light is suppressed.

As described above, according to the present invention, it is possible to enhance the uniformity of the spectral characteristics in the display area.

FIG. 2 shows a reflection type liquid crystal display device 1 according to the present invention.
00 shows the spectral reflectivity characteristic of 00. Reflective liquid crystal display device 10
The evaluation of the spectral characteristic of 0 was performed by measuring the wavelength dependence of the reflectance in the central portion 41 and the peripheral portion 42 of the display area shown in FIG. A solid line 51 and a broken line 52 shown in FIG.
1 and the reflectance at the peripheral portion 42 are shown.

As shown in FIG. 2B, the solid line 51 and the broken line 52 overlap each other, and
There is no difference in the wavelength dependence of the reflectance between the first and peripheral portions 42, and the wavelength region and the reflectance (all of the central wavelength, the intensity, and the half width of the selective reflection peak) that are selectively reflected are the same. Understand. As described above, it was confirmed that the reflective liquid crystal display device 100 had uniform spectral characteristics over the entire display area.

As a comparative example, a reflective liquid crystal display device 700 having a configuration in which horizontal alignment layers are provided on both surfaces of a liquid crystal layer as shown in FIG. 11 and vertical alignment layers provided on both surfaces of a liquid crystal layer as shown in FIG. Reflection type liquid crystal display device 8 having an improved configuration
13 and 14 show the spectral reflectance characteristics of No. 00, respectively. In the drawings, components having substantially the same functions as those of the reflective liquid crystal display device 100 are denoted by the same reference numerals for simplicity of description.

The reflection type liquid crystal display device 700 has the same configuration as the reflection type liquid crystal display device 100 except that the horizontal alignment layer 27 is provided on the second substrate 20, as shown in FIG. ing. FIG. 13 shows the spectral reflectance characteristics of the reflection type liquid crystal display device 700. The solid line 5 shown in FIG.
3 and the broken line 54 show the reflectance at the central portion 43 and the reflectance at the peripheral portion 44 of the display area shown in FIG. The solid line 53 and the broken line 54 shown in FIG. 13B do not overlap each other, and
And the peripheral region 44 has a wavelength region selectively reflected (the center wavelength of the selective reflection peak) different from each other,
It can be seen that the display is uneven in the display area. Also, reference numeral 4 in FIG. 11 and FIG.
Reference numeral 5 denotes a disclination line generated in the display area, and it can be seen that the number of spiral turns is different from each other in the areas 46 and 47.

The reflection type liquid crystal display device 800 has the same configuration as the reflection type liquid crystal display device 100 except that a vertical alignment layer 17 is provided on the first substrate 10 as shown in FIG. ing. FIG. 14 shows the spectral reflectance characteristics of the reflective liquid crystal display device 800. The solid line 5 shown in FIG.
Reference numerals 8 and broken lines 59 indicate the reflectance at the central portion 48 and the reflectance at the peripheral portion 49 of the display area shown in FIG. The solid line 58 and the broken line 59 shown in FIG. 14B do not overlap each other, and
And in the peripheral portion 49, the wavelength region selectively reflected (the center wavelength of the selective reflection peak) is different from each other,
It can be seen that the display is uneven in the display area. The selective reflection peaks of the solid line 58 and the broken line 59 are the solid line 51 and the broken line 52 (FIG.
3 and the dashed line 54 (FIG. 13B), the half-width is wider, the wavelength region to be selectively reflected is wider, and the color purity is lower.

In the first embodiment, as shown in FIG. 1, the reflection type liquid crystal display device 100 is provided on the first substrate 10.
That is, the horizontal alignment layer 16 is provided on the surface of the liquid crystal layer 30 on the viewer side, and the vertical alignment layer 26 is provided on the second substrate 20, that is, on the surface of the liquid crystal layer 30 on the side other than the viewer side. However, a configuration in which a vertical alignment layer is provided on the surface of the liquid crystal layer 30 on the viewer side and a horizontal alignment layer is provided on the opposite surface may be adopted.

FIG. 3 schematically shows a reflection type liquid crystal display device 100 'employing the above-described configuration. Reflective liquid crystal display device 1
00 ′ is provided with a vertical alignment layer 17 on the first substrate 10 and a horizontal alignment layer 27 on the second substrate 20,
It has the same configuration as the reflective liquid crystal display device 100, and uniform display quality can be obtained in the display area, similarly to the reflective liquid crystal display device 100.

Further, the inventor of the present invention evaluated the spectral characteristics of the reflection type liquid crystal display devices 100 and 100 ′, and examined the details in detail. As a result, as shown in FIG. The visibility of the reflected light differs between the case where the horizontal alignment layer is provided and the case where the vertical alignment layer is provided on the viewer side surface of the liquid crystal layer 30 as shown in FIG. I found that.

In the reflection type liquid crystal display device 100 shown in FIG. 1, the horizontal alignment layer 16 is formed on the surface of the liquid crystal layer 30 on the viewer side.
Is provided, the liquid crystal molecules in the vicinity of the surface of the liquid crystal layer 30 on the observer side have a uniform planar orientation, and the reflective surface has metallic luster. As a result, a display that is very bright in a specific viewing angle range and has high color purity is realized. From such a viewpoint, the reflective liquid crystal display device 100 can be suitably used for a device in which the display unit is limited to a specific viewing angle range, that is, a device having a relatively small display area.
It can be suitably used for watches, calculators, mobile phones, and the like. Of course, it is not limited to these uses.

The reflection type liquid crystal display device 100 'shown in FIG.
In the above, the vertical alignment layer 1 is formed on the surface of the liquid crystal layer 30 on the viewer side.
7, the liquid crystal molecules in the vicinity of the surface of the liquid crystal layer 30 on the observer side are not in planar alignment, and the reflection surface is slightly scattered. As a result, a display with good visibility is realized in a wide viewing angle range. From such a viewpoint, the reflective liquid crystal display device 100 ′ can be suitably used for a device that simultaneously observes a wide viewing angle range, that is, a device having a relatively large display area, such as a notebook personal computer or a portable information terminal. Can be suitably used. Of course, it is not limited to these uses.

The difference in visibility between the reflection type liquid crystal display devices 100 and 100 'will be described with reference to FIGS. FIGS. 4A and 5A show the wavelength dependence of the reflectance of the reflective liquid crystal display devices 100 and 100 ′, respectively. FIGS. 4B and 5B show the reflection type liquid crystal display devices 100 and 10 respectively.
It shows the angle dependence of the reflectance of 0 '. In this case, the reflection type liquid crystal display devices 100 and 100 ′ have a cell gap of about 20 μm and a liquid crystal layer 3
As a material of No. 0, about 40 wt% of a chiral agent CB15 (Merck) was added to a nematic liquid crystal material E7 (Merck).
A chiral nematic liquid crystal material is used which is mixed so that the spontaneous pitch of the helical structure is about 0.37 μm.
The chiral nematic liquid crystal layer 30 has a right-handed spiral structure, selectively reflects clockwise circularly polarized light in a wavelength region having a center wavelength of about 550 nm, and exhibits a green color.

As shown in FIGS. 4A and 4B,
In the reflection type liquid crystal display device 100, peaks of both the wavelength dependence of the reflectance and the angle dependence of the reflectance are relatively narrow, and a very bright display with a high color purity is realized in a specific viewing angle range. I understand.

As shown in FIGS. 5A and 5B, the reflection type liquid crystal display device 100 'has relatively wide peaks in both the wavelength dependence of the reflectance and the angle dependence of the reflectance. It can be seen that a display with good visibility is realized in a wide viewing angle range.

In consideration of the difference in visibility of the reflected light as described above, the display area can be appropriately selected by selecting an alignment layer provided on the viewer side of the liquid crystal layer according to the application of the reflection type liquid crystal display device. In this case, a reflective liquid crystal display device having a uniform display quality and having visibility suitable for use can be obtained. In this embodiment, the case where one liquid crystal layer is used has been described. However, when two or more liquid crystal layers are stacked, similarly, the horizontal alignment layer is formed on the surface of each liquid crystal layer on the viewer side. Is provided, very bright display with high color purity is realized in a specific viewing angle range, and visibility is wide in a wide viewing angle range by providing a vertical alignment layer on the viewer side surface of each liquid crystal layer. A good display is realized.

In the first embodiment, the liquid crystal layer 30
Is preferably defined by a columnar spacer. In that case, it is preferable that the columnar spacer is further formed on a substrate provided with a vertical alignment layer.

FIG. 6 schematically shows a reflection type liquid crystal display device 200 employing such a configuration. The reflection type liquid crystal display device 200 has the same configuration as the reflection type liquid crystal display device 100 except that a columnar spacer 34 is formed on the second substrate 20.

In the reflection type liquid crystal display device 200, the thickness of the liquid crystal layer 30 is determined by the columnar spacers 34 which can be formed on the second substrate 20 with relatively high positional accuracy. By forming a portion other than the elementary region in a portion that does not contribute to display, it is possible to improve the aperture ratio and to reduce the influence of the alignment of the liquid crystal molecules near the columnar spacer on the display. Further, since the columnar spacer 34 is formed on the second substrate 20 provided with the vertical alignment layer 26, it is necessary to perform a rubbing process on the second substrate 20 on which the columnar spacer 34 is formed in a manufacturing process. There is no. Therefore, the loss of the columnar spacer 34 is prevented, and the alignment defect due to the rubbing shadow caused by the columnar spacer 34 does not occur.

The thickness of the liquid crystal layer 30 (cell gap)
May be defined by spherical spacers scattered between the first substrate 10 and the second substrate 20, or the columnar spacers 34 may be formed on the first substrate 10 so that the The effect of the present invention that uniform display quality can be obtained is not impaired. (Embodiment 2) FIG. 7 schematically shows a reflection type liquid crystal display device 300 according to Embodiment 2 of the present invention.

The reflection type liquid crystal display device 300 includes two liquid crystal layers 30a and 30b that selectively reflect light in a specific wavelength region, a pair of alignment layers 16 and 71 provided on both surfaces of the liquid crystal layer 30a, A pair of alignment layers 27 and 72 provided on both surfaces of the liquid crystal layer 30b, and a pair of electrodes 14 and 24 for applying a voltage to the two liquid crystal layers 30a and 30b.
One of the pair of alignment layers 16 and 71 provided on both sides of the liquid crystal layer 30a is the horizontal alignment layer 16, the other is the vertical alignment layer 71, and the liquid crystal layer 30
b of the pair of alignment layers 27 and 72 provided on both sides, one is the horizontal alignment layer 27 and the other is the vertical alignment layer 7.
2 is provided.

Further, the two liquid crystal layers 30a and 30b
Are stacked on each other via a dielectric sheet 70,
The pair of electrodes 14 and 24 are provided so as to face each other via the two liquid crystal layers 30 a and 30 b and the dielectric sheet 70, and the two liquid crystal layers 30 a and 30
b, one liquid crystal layer 30a selectively reflects right circularly polarized light (clockwise circularly polarized light) in a specific wavelength region, and the other liquid crystal layer 30b selectively reflects left circularly polarized light (clockwise circularly polarized light) in a specific wavelength region. It has a function of selectively reflecting circularly polarized light.

The liquid crystal layer 30a for selectively reflecting right circularly polarized light
Is provided between the first substrate 10 and the dielectric sheet 70, and the liquid crystal layer 30b that selectively reflects left circularly polarized light is
It is provided between the second substrate 20 and the dielectric sheet 70.

The first substrate 10 is the liquid crystal layer 3 of the transparent substrate 12
The transparent electrode 14 is formed on the surface on the 0a side, and a horizontal alignment layer 16 is formed on the transparent electrode 14.

On the other hand, the second substrate 20 has a transparent electrode 24 formed on the surface of the transparent substrate 22 on the liquid crystal layer 30b side.
A horizontal alignment layer 27 is further formed on the transparent electrode 24, and a light absorbing layer 23 is formed on the surface of the transparent substrate 22 on the side other than the liquid crystal layer 30b side.

A vertical alignment layer 71 is formed on the surface of the dielectric sheet 70 provided between the two liquid crystal layers 30a and 30b on the liquid crystal layer 30a side.
A vertical alignment layer 72 is formed on the side surface. The thickness of the dielectric sheet 70 is preferably 30 μm or less, more preferably 10 μm or less, in order to reduce parallax and to keep the driving voltage low. The influence of the thickness of the dielectric sheet 70 on the driving voltage is as follows.
This is because the driving voltage applied between the pair of transparent electrodes 14 and 24 is divided by the electric capacity of the liquid crystal layers 30a and 30b and the electric capacity of the dielectric sheet 70. For this reason, for example, when the thickness of the dielectric sheet 70 increases, the voltage applied to the liquid crystal layers 30a and 30b decreases, so that the voltage applied to the liquid crystal layers 30a and 30b is set to a predetermined value. , A pair of transparent electrodes 14
And the drive voltage applied between 24 must be high.

In the reflection type liquid crystal display device 300 according to Embodiment 2 of the present invention, one of the pair of alignment layers provided on both surfaces of the liquid crystal layers 30a and 30b is a horizontal alignment layer and the other is a pair. Is a vertical alignment layer, so that uniform display quality can be obtained in the display area, similarly to the reflective liquid crystal display device 100 according to the first embodiment.

In the second embodiment, of the two liquid crystal layers 30a and 30b, one liquid crystal layer 30a selectively reflects right circular knitted light in a specific wavelength region, and the other liquid crystal layer 30b has a specific liquid crystal layer 30b. Reflects left circularly polarized light in the wavelength range of
Both right-handed circularly polarized light and left-handed circularly polarized light included in the incident light can be used for display, and a very bright display is realized.

As a configuration of a reflection type liquid crystal display device which can use both right circularly polarized light and left circularly polarized light for display, for example,
A configuration in which two liquid crystal layers each sandwiched between a pair of substrates is conceivable is also considered.
Since the two substrates are stacked via one substrate, parallax occurs. In the second embodiment, since the two liquid crystal layers 30a and 30b are stacked via the dielectric sheet 70, no parallax occurs.

Further, the two liquid crystal layers 30a and 30b
Are provided with the vertical alignment layer on the surface on the dielectric sheet 70 side, so that the horizontal alignment layer 16
No stress is applied to the dielectric sheet 70 when the rubbing process is performed on the dielectric sheet 70. As a result, the strength reliability is increased. Further, since the stress does not reach the dielectric sheet 70, a relatively thin dielectric sheet can be used as the dielectric sheet 70, and as a result, the parallax can be further reduced and the driving voltage is suppressed to be low. be able to.

Further, of the two liquid crystal layers 30a and 30b, the horizontal alignment layer 16 is provided on the observer side surface of one of the liquid crystal layers 30a, and is perpendicular to the observer side surface of the other liquid crystal layer 30b. Since the alignment layer 27 is provided, of the right-handed circularly polarized light and the left-handed circularly polarized light included in the incident light, the right-handed circularly polarized light has liquid crystal molecules near the surface on the observer side in a uniform planar alignment. The left circularly polarized light reflected by the liquid crystal layer 30a is reflected by the liquid crystal layer 30b in which the liquid crystal molecules near the surface on the observer side are not in a planar alignment. As a result, very bright and high color purity is achieved in a specific viewing angle range, and display with good visibility is realized in a wide viewing angle range. Note that the same display can be realized by a configuration in which a vertical alignment layer is provided on the viewer side surface of the liquid crystal layer 30a and a horizontal alignment layer is provided on the viewer side surface of the liquid crystal layer 30b.

In the second embodiment, as described above,
Of the two liquid crystal layers 30a and 30b, the horizontal alignment layer 16 is provided on the observer side surface of one liquid crystal layer 30a, and the vertical alignment layer 2 is provided on the observer side surface of the other liquid crystal layer 30b.
7 is provided, but two liquid crystal layers 30a are provided.
And 30b, a horizontal alignment layer may be provided on the viewer side surface. FIG. 8 schematically shows a reflective liquid crystal display device 400 employing such a configuration. The reflection type liquid crystal display device 400 has a reflection mode except that the vertical alignment layer 26 is formed on the second substrate 20 and the horizontal alignment layer 73 is provided on the surface of the dielectric sheet 70 on the liquid crystal layer 30b side. It has the same configuration as the liquid crystal display device 300. Like the reflective liquid crystal display device 300, the reflective liquid crystal display device 400 can obtain uniform display quality in the display area and can use both left and right circularly polarized light,
Although a very bright display is realized, the visibility of the reflected light is different from that of the reflective liquid crystal display device 300 as described below.

In the reflection type liquid crystal display device 400 shown in FIG. 8, a horizontal alignment layer is provided on each of the two liquid crystal layers 30a and 30b on the viewer side.
The right circularly polarized light and the left circularly polarized light contained in the incident light are respectively reflected by the liquid crystal layers 30a and 30b in which liquid crystal molecules in the vicinity of the surface on the observer side have a uniform planar orientation. As a result, a display that is very bright and has high color purity in a specific viewing angle range is realized.

Alternatively, two liquid crystal layers 30a and 30
Each of b may have a configuration in which a vertical alignment layer is provided on the viewer side surface. FIG. 9 schematically shows a reflective liquid crystal display device 500 employing such a configuration. The reflection type liquid crystal display device 500 includes a vertical alignment layer 1 on a first substrate 10.
7 are formed, and the liquid crystal layer 30a of the dielectric sheet 70 is formed.
Except that a horizontal alignment layer 74 is provided on the side surface.
It has the same configuration as the reflective liquid crystal display device 300. This reflection type liquid crystal display device 500 includes a reflection type liquid crystal display device 3.
As in the case of 00, a uniform display quality can be obtained in the display area, and both right and left circularly polarized lights can be used, and a very bright display is realized. Different from 300.

In the reflection type liquid crystal display device 500 shown in FIG. 9, since the two liquid crystal layers 30a and 30b each have a vertical alignment layer on the viewer side,
The right circularly polarized light and the left circularly polarized light included in the incident light are respectively reflected by the liquid crystal layers 30a and 30b in which the liquid crystal molecules near the viewer side are not in the planar alignment. As a result, a display with good visibility is realized in a wide viewing angle range.

By taking into account the difference in visibility of reflected light as described above, an alignment layer provided on the viewer side of the liquid crystal layer is appropriately selected according to the application of the reflection type liquid crystal display device. In this case, a reflective liquid crystal display device having a uniform display quality and having visibility suitable for use can be obtained.

In the second embodiment, the thickness (cell gap) of the two liquid crystal layers 30a and 30b is preferably defined by the columnar spacer. Further, when a vertical alignment layer is provided on the surface of the two liquid crystal layers 30a and 30b on the side of the dielectric sheet 70, the columnar spacers serve as two liquid crystal layers 30a and 30b.
Ob is preferably formed on the first substrate 10 and the second substrate 20 provided so as to oppose the dielectric sheet 70 via each of Ob. Further, instead of the dielectric sheet 70 having the vertical alignment layers 71 and 72 provided on both surfaces, a vertical alignment dielectric sheet 70 ′ having functions as the vertical alignment layers 71 and 72 may be used.

FIG. 10E schematically shows a reflection type liquid crystal display device 600 employing such a configuration. The reflective liquid crystal display device 600 has columnar spacers 34 a and 34 b formed on the first substrate 10 and the second substrate 20, respectively, and has a function as vertical alignment layers 71 and 72 instead of the dielectric sheet 70. Oriented dielectric sheet 7
Except that 0 ′ is provided, the reflective liquid crystal display device 3
It has the same configuration as 00.

In the reflective liquid crystal display device 600, the thickness of the two liquid crystal layers 30a and 30b is defined by the columnar spacers 34a and 34b which can be formed on the substrate with relatively high positional accuracy. The first substrate 1 is arranged such that the spacers 34a and 34b face each other.
And the vertical alignment dielectric sheet 70 ′ is sandwiched from above and below by being formed on the
The thickness (cell gap) of the liquid crystal layers 30a and 30b can be defined with high accuracy. Further, since the vertically aligned dielectric sheet 70 'can be supported so as to be sandwiched from above and below, a relatively thin dielectric sheet can be used as the vertically aligned dielectric sheet 70', and as a result, parallax is further reduced. And the driving voltage can be kept low.

Further, the columnar spacers 34a and 34b
Is formed in a portion other than the picture element region that does not contribute to the display, thereby improving the aperture ratio and reducing the influence of the orientation of the liquid crystal molecules near the columnar spacer on the display. Further, since the vertical alignment dielectric sheets 70 ′ having the functions as the vertical alignment layers 71 and 72 are used instead of the dielectric sheet 70, compared with the case where the vertical alignment layers 71 and 72 are formed on the dielectric sheet 70, As a result, the number of manufacturing steps can be reduced.

The reflection type liquid crystal display device 600 is manufactured, for example, as follows. FIGS. 10 (a) to 10 (e)
FIG. 10 is a process cross-sectional view illustrating a manufacturing process of the reflective liquid crystal display device 600.

First, as shown in FIG. 10A, a transparent substrate 1 on which a transparent electrode 14 made of, for example, an ITO layer is formed.
2 (for example, a glass substrate), a photosensitive resin 34a ′ (for example, an acrylic photosensitive resin) to be the columnar spacer 34a is applied by, for example, a spin coating method. In this embodiment, the photosensitive resin 34a 'is formed to have a thickness of about 5 μm.

Next, as shown in FIG. 10B, the photosensitive resin 34a 'is patterned by a photolithography process to form a columnar spacer 34a.
At this time, the columnar spacer 34a is preferably patterned so as to be formed outside the pixel region in order to prevent a decrease in the aperture ratio and reduce the influence of the orientation of the liquid crystal molecules near the columnar spacer on display. .

Next, as shown in FIG. 10C, a horizontal alignment layer 16 is formed on the transparent substrate 12 on which the columnar spacers 34a are formed so as to have a thickness of, for example, about 50 nm (500 °). The horizontal alignment layer 16 is formed, for example, by first using JSR
AL4552 manufactured by Co., Ltd. is applied by a spin coating method, then baked at about 180 ° C. for about 60 minutes, and then subjected to a rubbing treatment to give an alignment controlling force for aligning the liquid crystal molecules in a specific azimuthal direction. Thus the first
The substrate 10 is completed. Also, the second substrate 20 having the transparent electrode 24, the columnar spacers 34b, and the horizontal alignment layer 27 formed on the transparent substrate 22 is prepared by the same process as the above-described process shown in FIGS. 10A to 10C. I do. At this time,
It is preferable that the columnar spacer 34b is formed so as to face the columnar spacer 34a when it is bonded to the first substrate later.

Thereafter, as shown in FIG.
A vertical alignment dielectric sheet (for example, a polyimide film film having a thickness of about 7.5 μm and having both surfaces subjected to vertical alignment processing) 70 ′ is attached on the substrate 10, and the second substrate 20 is attached.

Then, as shown in FIG.
A liquid crystal material, which will be described later, is injected and sealed between the substrate and the vertically aligned dielectric sheet 70 'and between the second substrate and the vertically aligned dielectric sheet 70' to form the liquid crystal layer 30a and the liquid crystal layer 30b. Form. Thereafter, a light absorbing layer 23 for absorbing light in the visible light region is formed outside the second substrate 20 (on the side other than the liquid crystal layer 30b side). It should be noted that the arrangement and the formation time of the light absorbing layer 23 are not limited to this, and the second substrate 20
May be formed on the liquid crystal layer 30b side, or may be formed at any point in the above-described process.

As a material of the liquid crystal layer 30a, for example, about 25.2 wt% of a chiral agent R811 (manufactured by Merck) is mixed with a nematic liquid crystal material ZLI4792 (manufactured by Merck), and the spontaneous pitch of the spiral structure is about 0.36 μm. A chiral nematic liquid crystal material is used. The chiral nematic liquid crystal layer 30a has a right-handed helical structure, selectively reflects clockwise circularly polarized light in a wavelength region having a center wavelength of about 550 nm, and exhibits a green color. In addition,
Reference numeral 32a in FIG. 1 schematically shows a helical structure of the chiral nematic liquid crystal layer 30a.

As a material of the liquid crystal layer 30b, for example, about 25.2 wt% of a chiral agent S811 (manufactured by Merck) is mixed with a nematic liquid crystal material ZLI4792 (manufactured by Merck), and the spontaneous pitch of the helical structure is about 0.36 μm. A chiral nematic liquid crystal material is used. The chiral nematic liquid crystal layer 30b has a left-handed helical structure, selectively reflects left-handed circularly polarized light in a wavelength region having a center wavelength of about 550 nm, and exhibits a green color. In addition,
Reference numeral 32b in FIG. 1 schematically shows the spiral structure of the chiral nematic liquid crystal layer 30b.

In the second embodiment, the liquid crystal layer 30
Although the liquid crystal layer 30a selectively reflects right circularly knitted light and the liquid crystal layer 30b selectively reflects left circularly polarized light, the present invention is not limited to this. The liquid crystal layer 30a selectively reflects left circularly knitted light. Alternatively, the liquid crystal layer 30b may be configured to selectively reflect right circularly polarized light. Further, in the second embodiment, in order to increase the use efficiency of light in a specific wavelength region to increase color purity and luminance,
A wavelength region where the liquid crystal layer 30a selectively reflects;
The wavelength region where 0b is selectively reflected is configured to be substantially the same wavelength region as each other, but is not limited thereto, may be different wavelength regions, may partially overlap each other, One may encompass the other.

By the steps shown in FIGS. 10A to 10E, the reflection type liquid crystal display device 600 is completed.
In the above description, the case where the vertically oriented dielectric sheet 70 'is used instead of the dielectric sheet 70 has been described, but of course, the dielectric sheet 70 may be used,
As the dielectric sheet 70, for example, a glass sheet can be used. The vertical alignment layers provided on both surfaces of the dielectric sheet 70 may be formed by a known method using a known material. (Other Embodiments) In the above embodiments, the reflection type liquid crystal display device provided with one or two liquid crystal layers for selectively reflecting light in a specific wavelength region has been described. The present invention is not limited to the embodiment, and can be suitably used in a reflection type liquid crystal display device including three or more liquid crystal layers that selectively reflect light in a specific wavelength region. For example, a configuration in which three liquid crystal layers that selectively reflect light in the wavelength regions corresponding to red, green, and blue, respectively, and a right circular polarization and a left circular polarization in the wavelength regions corresponding to the three colors described above are further provided. The present invention can also be suitably used for a reflection type liquid crystal display device of a multi-color display in which six liquid crystal layers are stacked in order to use both of them for display. Of course, the present invention can also be suitably used for a reflection type liquid crystal display device for full color display having a configuration in which more liquid crystal layers are stacked. Even in a case where three or more liquid crystal layers are stacked, desired visibility can be obtained by appropriately selecting an alignment layer provided on the viewer side of each liquid crystal layer.

In the above embodiment, the case where the chiral nematic liquid crystal layer is used as the liquid crystal layer that selectively reflects light in a specific wavelength range has been described. However, the present invention is not limited to this. Alternatively, a chiral smectic liquid crystal layer or the like may be used.

Further, the wavelength region in which the above-mentioned liquid crystal layer selectively reflects is not limited to the above embodiment, but may be appropriately set according to the application. When setting this wavelength region, in the reflection type liquid crystal display device according to the present invention, since the number of spiral turns of the spiral structure of the liquid crystal layer continuously changes, the spiral pitch is not stretched or shrunk. The spontaneous pitch of the liquid crystal material to be a liquid crystal layer (set as a liquid crystal material) is a helical pitch in the liquid crystal layer.
Therefore, the wavelength region to be selectively reflected can be set to a desired region with high accuracy.

[0107]

According to the present invention, a reflective liquid crystal display having a uniform display quality in a display area is realized by combining a horizontal alignment layer and a vertical alignment layer as alignment layers provided on both sides of a liquid crystal layer. An apparatus can be provided.

Further, by appropriately selecting an alignment layer provided on the observer side of the liquid crystal layer according to the use of the reflection type liquid crystal display device, a reflection type liquid crystal display having a viewing angle optimized for the use is provided. An apparatus is provided. Therefore, the reflection type liquid crystal display device according to the present invention can be suitably used for various applied products requiring various viewing angle characteristics.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a reflective liquid crystal display device 100 according to a first embodiment of the present invention.

FIGS. 2A and 2B are diagrams showing spectral reflectance characteristics of the reflective liquid crystal display device 100 according to the first embodiment of the present invention.

FIG. 3 is a sectional view schematically showing a reflective liquid crystal display device 100 ′ according to Embodiment 1 of the present invention.

4A is a diagram illustrating the wavelength dependence of the reflectance of the reflection type liquid crystal display device 100, and FIG. 4B is a diagram illustrating the angle dependence of the reflectance of the reflection type liquid crystal display device 100. is there.

5A is a diagram illustrating the wavelength dependence of the reflectance of the reflective liquid crystal display device 100 ′, and FIG. 5B is a diagram illustrating the angle dependence of the reflectance of the reflective liquid crystal display device 100 ′. FIG.

FIG. 6 is a sectional view schematically showing a reflective liquid crystal display device 200 according to Embodiment 1 of the present invention.

FIG. 7 is a sectional view schematically showing a reflective liquid crystal display device 300 according to a second embodiment of the present invention.

FIG. 8 is a cross-sectional view schematically showing a reflective liquid crystal display device 400 according to Embodiment 2 of the present invention.

FIG. 9 is a sectional view schematically showing a reflective liquid crystal display device 500 according to Embodiment 2 of the present invention.

FIGS. 10A to 10E are cross-sectional views schematically showing manufacturing steps of a reflective liquid crystal display device 600 according to Embodiment 2 of the present invention.

FIG. 11 is a sectional view schematically showing a reflection type liquid crystal display device 700.

FIG. 12 is a sectional view schematically showing a reflective liquid crystal display device 800.

FIGS. 13A and 13B are diagrams showing spectral reflectance characteristics of the reflection type liquid crystal display device 700. FIGS.

FIGS. 14A and 14B are diagrams illustrating spectral reflectance characteristics of a reflection type liquid crystal display device 800. FIGS.

[Explanation of symbols]

 Reference Signs List 10 first substrate 12 transparent substrate 14 transparent electrode 16 horizontal alignment layer 17 vertical alignment layer 20 second substrate 22 transparent substrate 23 light absorption layer 24 transparent electrode 26 vertical alignment layer 27 horizontal alignment layer 30, 30a, 30b liquid crystal layer 34, 34a , 34b columnar spacer 45 disclination line 70 dielectric sheet 70 'vertical alignment dielectric sheet 71, 72 vertical alignment layer 73, 74 horizontal alignment layer 100 reflective liquid crystal display device 100' reflective liquid crystal display device 200 reflective liquid crystal display Device 300 Reflective liquid crystal display 400 Reflective liquid crystal display 500 Reflective liquid crystal display 600 Reflective liquid crystal display 700 Reflective liquid crystal display 800 Reflective liquid crystal display

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yasutaka Ito 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term (in reference) 2H089 LA06 QA14 QA16 RA11 TA04 TA15 2H090 LA02 LA09 MA01 MA02 MA12 MB01 2H091 FA08X FA08Z FA41Z FA44Z GA08 HA11 LA16 LA19

Claims (9)

[Claims] At least one liquid crystal layer selectively reflecting light in a specific wavelength region, a pair of alignment layers provided on both surfaces of the at least one liquid crystal layer, and a voltage applied to the at least one liquid crystal layer. A reflection type liquid crystal display device, comprising: at least one pair of electrodes for applying a voltage; and one of the pair of alignment layers is a horizontal alignment layer and the other is a vertical alignment layer. 2. The reflection type liquid crystal display device according to claim 1, wherein the horizontal alignment layer is provided on a surface of the at least one liquid crystal layer on a viewer side. 3. The reflection type liquid crystal display device according to claim 1, wherein the vertical alignment layer is provided on a surface of the at least one liquid crystal layer on a viewer side. 4. The at least one liquid crystal layer is two liquid crystal layers stacked on each other via a dielectric sheet, and the at least one pair of electrodes is connected via the two liquid crystal layers and the dielectric sheet. One of the two liquid crystal layers selectively reflects right circular knitted light in a specific first wavelength region, and the other is left circularly polarized light in a specific second wavelength region. 2. The reflective liquid crystal display device according to claim 1, which selectively reflects light. 5. The horizontal alignment layer is provided on a viewer-side surface of one of the two liquid crystal layers, and the vertical alignment layer is provided on a viewer-side surface of the other liquid crystal layer. The reflective liquid crystal display device according to claim 4, wherein the reflective liquid crystal display device is provided. 6. The reflection type liquid crystal display device according to claim 4, wherein the horizontal alignment layer is provided on a surface on a viewer side of each of the two liquid crystal layers. 7. The reflection type liquid crystal display device according to claim 4, wherein the vertical alignment layer is provided on a surface on the viewer side of each of the two liquid crystal layers. 8. The thickness of the at least one liquid crystal layer is:
4. The reflection type liquid crystal display device according to claim 1, wherein said at least one liquid crystal layer is defined by a columnar spacer formed on a substrate provided on said vertical alignment layer side. 9. The vertical alignment layer is provided on the surface of the two liquid crystal layers on the dielectric sheet side, and the thickness of each of the two liquid crystal layers is equal to the thickness of the two liquid crystal layers. 5. The reflection type liquid crystal display device according to claim 4, wherein the reflection type liquid crystal display device is defined by columnar spacers formed on a substrate provided so as to face the dielectric sheet with each interposed therebetween.