JP2001133770A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display device which increases the range of colors to be displayed when an auxiliary light source is turned on in a dark environment. SOLUTION: The liquid crystal display device consists of a first substrate 11, second substrate 12, liquid crystal layer 10, auxiliary light source 50 and driving device. The liquid crystal layer is held between the first substrate and the second substrate to form a liquid crystal cell, and the driving device is connected to the first substrate and the second substrate. The device is equipped with a voltage applying means on the faces near the liquid crystal layer of the first substrate and the second substrate. The first substrate has a first reflection plate 21 on the face near the liquid crystal layer, and the second substrate has a second reflection plate 22 and color conversion layers 44, 45, 46 on the face near the liquid crystal layer. The second reflection plate has an opening 23 for the auxiliary light source in a nonpixel part. The auxiliary light source is disposed on the back of the liquid crystal cell and near the second substrate. The light from the auxiliary light source passes through the color conversion layers and the opening for the auxiliary light source and then enters the first reflection plate and then the second reflection plate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a reflection type liquid crystal display device which requires an auxiliary light source.

[0002]

2. Description of the Related Art In a transmission type liquid crystal display device using a backlight as a light source, the contrast ratio is reduced due to surface reflection of light incident from the outside, and the color specification range is reduced. In particular, in a bright environment such as outdoors on a sunny day, the amount of surface reflection is larger than the amount of light of the backlight, so that the visibility is reduced so that the user can hardly recognize the display. On the other hand, the reflection type color liquid crystal display device reflects the light incident from the outside and displays the same, so that a constant contrast ratio and a color specification range can be obtained regardless of the surrounding environment. In particular, in a bright environment such as outdoors in fine weather, better visibility than a transmissive liquid crystal display device can be obtained. However, in a dark environment such as indoors where lighting is weak, the amount of incident light is reduced, so that the display of the reflective liquid crystal display device is dark, and the visibility is reduced. Even if a reflective color liquid crystal display device having a reflectance and a contrast ratio equal to or higher than that of a printed matter is realized, it is inevitable that the display becomes dark in a darker environment. Therefore, an auxiliary light source is indispensable for the reflection type color liquid crystal display device. As the auxiliary light source, for example,
There is a front light described in Japanese Patent Publication No. 308 and Japanese Patent Application Laid-Open No. 10-268306. The front light includes a light source such as a fluorescent lamp and a light guide plate. The light source is located on the side of the light guide plate, and the light generated here enters the light guide plate. The light guide plate is distributed so as to cover the entire surface of the display unit, and light is reflected on the upper surface of the light guide plate to illuminate the display portion. Alternatively, Japanese Patent Application Laid-Open No. 10-21799 describes a method of arranging a planar auxiliary light source so as to cover the entire display portion and directly illuminating the display portion. The auxiliary light source is, for example, an electroluminescent element, and the electrodes are transparent electrodes, so that the display unit can be viewed through the auxiliary light source. In a reflection type color liquid crystal display device, a color filter is used in the same manner as in a transmission type color liquid crystal display device, but a light color filter having a small amount of dye is used in order to improve the reflectance when an auxiliary light source is not used. The light color filter has a higher transmittance than a normal color filter, but has a lower color purity.

[0003]

The color of a light color filter has lower color purity than a normal color filter. When the color specification range is determined only by the color purity of the color filter, the color specification range of the reflective color liquid crystal display device using the light color filter is narrower than that of the transmission color liquid crystal display device. In a bright environment such as outdoors during the daytime, the intensity of light incident on the liquid crystal display device from the surroundings is high, and the surface reflected light may be strong enough to be compared with the backlight light of the transmission type color liquid crystal display device. In such a case, the contrast ratio of the transmission type color liquid crystal display device is significantly reduced, and the color specification range is also reduced. On the other hand, in the reflection type color liquid crystal display device, the reflection on the reflection plate is stronger than the surface reflection, so that the reflection type liquid crystal display device is not affected. In an environment where surface reflection is dominant, a reflective color liquid crystal display device may have a higher contrast ratio and a wider color specification range. On the other hand, in a dark environment, the brightness can be made equal to that of the transmissive liquid crystal display device by combining the above-mentioned auxiliary light source with the reflective color liquid crystal display device and sufficiently increasing the amount of light. However, at this time, since the color ranges of both are determined by the color purity of the color filters, the color range of the reflective color liquid crystal display device is narrower than that of the transmissive color liquid crystal display device. Therefore, in a dark environment, the visibility of the reflection type liquid crystal display device was inferior to that of the transmission type liquid crystal display device. The conventional auxiliary light source has only a function of improving the brightness of the reflective color liquid crystal display device in a dark environment. If the color specification range can be expanded in addition to the brightness when the auxiliary light source is turned on, the visibility of the reflective color liquid crystal display device in a dark environment can be made closer to that of the transmissive liquid crystal display device.

An object of the present invention is to provide a reflection type liquid crystal display device which can further expand a color specification range when an auxiliary light source is turned on in a dark environment.

[0005]

The above object is achieved by a first substrate having a first reflection plate on a side close to a liquid crystal layer, and a second substrate having a second reflection plate on a side close to the liquid crystal layer. A second reflector having an auxiliary light source opening in a non-pixel portion, the auxiliary light source being located behind the liquid crystal cell and close to the second substrate, and the auxiliary light source light The problem is solved by entering the first reflection plate after passing through the color conversion layer and the auxiliary light source opening, and thereafter entering the second reflection plate. Here, the color conversion layers are composed of color conversion layers having red, green, and blue emission colors, and light emitted from each color conversion layer selectively enters the second reflector corresponding to a different pixel. In addition, each pixel includes a color filter, and the color filter includes a color filter having red, green, and blue transmitted light colors, and the red color filter is distributed close to the red color conversion layer, and a green color filter is provided. Are distributed close to the green color conversion layer, and the blue color filter is distributed close to the blue color conversion layer. In addition, a slope layer is provided between the first reflector and the first substrate, and a reflection surface normal of the first reflector is inclined with respect to a normal of the first substrate along the slope of the slope layer. . Further, the first substrate or the second substrate has columnar projections on a side close to the liquid crystal layer, the columnar projections have an inclined surface, and a part of the inclined surface overlaps with the auxiliary light source opening and is made of metal. It has a layer and functions as a first reflector. In addition, a microlens array is provided between the second substrate and the auxiliary light source, and the microlens array focuses the auxiliary light source on the auxiliary light source opening.

In the present invention, the first substrate has an active element on the side close to the liquid crystal layer, and the active element is connected to a signal wiring for transmitting an image signal and a scanning signal to the pixel electrode, and to the pixel electrode. Some of them overlap the auxiliary light source opening and are distributed on the slope of the inclined layer, and can function as the first reflector. Further, the second substrate may have a phase plate on the side close to the liquid crystal layer. The second reflector may be provided with a concavo-convex forming layer formed by stamping. Further, the first polarizing plate can be arranged outside the first substrate, and the second polarizing plate can be arranged on the side of the second substrate close to the liquid crystal layer. In addition, a microprism array is provided between the second substrate and the auxiliary light source, and the cross section of the microlens array includes a semicircular or arc-shaped curve, and the center of the semicircle or arc is viewed from the normal direction of the substrate. It can overlap with the auxiliary light source opening.
Also, the cross-sectional shape of the microlens array is a repetitive structure consisting of a substantially right triangle or a straight short side and a curved long side, and the microprism array is configured such that the average of the auxiliary light source propagation directions is inclined from the substrate normal. And the auxiliary light source light is focused on the auxiliary light source opening.

[0007]

Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the liquid crystal display device according to the first embodiment of the present invention, and is a cross-sectional view taken along cutting lines 3 and 4 parallel to the pixel electrode 17 as shown in FIG.
In FIG. 1, a first substrate 11 of the pair of substrates is made of borosilicate glass, has a thickness of 0.7 mm,
An insulating layer 31, an inclined layer 32, an active element 25 (FIG. 2B), a pixel electrode 17, and a first alignment film 13 are sequentially stacked on the side close to the liquid crystal layer 10. The pixel electrode 17
It is made of Indium Tin Oxide (ITO).
It is connected to the. The active element 25 is an inverted staggered thin film transistor, and is connected to the gate wiring 27 and the signal wiring 26. Gate wiring 27 and signal wiring 26
Is provided with an antireflection layer 29 on the side close to the first substrate 11. The antireflection layer 29 is made of aluminum oxide and has a thickness of 0.2 μm. Alternatively, the antireflection layer 29 may be made of chromium oxide and the first electrode may be made of chromium. Alternatively, the antireflection layer 29 may be a light absorber such as a metal oxide or a pigment. The gate wiring 27 and the signal wiring 26 are insulated by the insulating layer 31. The insulating layer 31 is made of silicon nitride and has a thickness of 1 μm. Graded layer 3
2 is formed between the signal wiring 26 and the insulating layer 31. FIG. 2A shows the first substrate 1 viewed from the normal direction of the substrate.
1, which shows a state in which the inclined layer 32 is formed on the insulating layer 31. The shape of the inclined layer 32 is a trapezoid having a gentle slope, and the bottom of the trapezoid is a rectangle of about 200 μm × 30 μm. The top of the trapezoid is a smaller rectangle, approximately 180 μm × 10 μm. The height of the trapezoid is about 3 μm. FIG. 2B shows a state where the pixel electrode 17 is formed on the inclined layer 32. One of the slopes of the inclined layer 32 overlaps with the pixel electrode 17, and the side of the pixel electrode 17 close to the liquid crystal layer 10 is a mirror surface, and thus functions as a reflector. When the portion where the pixel electrode 17 overlaps the inclined layer 32 is called a first reflector 21, the first reflector 21 is
2, the light incident perpendicularly to the macroscopic plane of the first substrate 11 is reflected in the direction in which the normal of the reflection surface is directed. The pixel electrode 17 forms one pixel, has a substantially square shape, and a size of about 275 μm × 8
0 μm. The distance between the pixel electrodes is 25 μm in the vertical direction,
It is 20 μm in the lateral direction, and the aperture ratio is about 75%. The first substrate 11 includes the pixel electrodes 17 in a matrix, and the number thereof is 480 in the vertical direction and 640 × in the horizontal direction.
There are three. For the first alignment film 13, a polyimide organic polymer manufactured by Nissan Chemical Industries, Ltd. was used.

The second substrate 12 of the pair of substrates is made of the same material and has the same thickness as the first substrate.
46, a first flattening layer 47, an unevenness forming layer 20, a second reflector 22, a second flattening layer 48, a color filter 41,
42, 43, a third planarization layer 49, a common electrode 16, and a second alignment film 14. The color conversion layers 44, 45, 46
The layer thickness is about 2 μm, and it has a stripe shape. Red color conversion layer 44, green color conversion layer 45, blue color conversion layer 46
Are sequentially arranged, and the width of the stripe and the width between the stripes are 50 μm and 250 μm, respectively. The color conversion layer is made of a binder resin containing a dye, and the dye of the red color conversion layer 44 is a cyanine dye, 4-dicyanomethylene-2-methyl-6- (p-dimethylaminostillyl).
-4H-pyran was used. The dyes of the green color conversion layer 45 include coumarin-based dyes 2, 3, 5, 6-1H and 4H-tetrahydro-8-trifluoromethylquinolizino (9, 9a,
1-gh) Coumarin was used. As the dye for the blue color conversion layer 46, 1,4-bis (2-methylstil) benzene, which is a stilbene dye, was used. In addition, polymethyl methacrylate was used as the binder resin. The mixing ratio of each dye to the binder resin was 5% to 10%. The first planarization layer 47 is made of an acrylic resin and has a thickness of about 2
μm. The unevenness forming layer 20 is a positive type or negative type photoresist, and is distributed in a large number between the first planarizing layer 47 and the second reflector 22 in an island shape. After being formed into a cylindrical shape by photolithography, the shape is deformed by heating and then a convex surface having a gentle inclination is formed. The diameter of the convex surface is 15μ
m and the height is 1 μm. The reflection electrode is made of Al, and its layer thickness is 200 nm. The surface of the reflective electrode has a gentle uneven surface along the convex surface forming layer, and can reflect light in various directions different from the regular reflection direction of the macroscopic plane of the reflective electrode. The unevenness forming layer 20 is distributed on a portion of the first substrate 11 corresponding to the pixel electrode 17. The reflective electrode is not distributed over the entire surface of the second substrate 12, and a portion where the reflective electrode is not distributed is referred to as an auxiliary light source opening 23. When the auxiliary light source opening 23 has a rectangular shape. Yes,
The length of the short side is 8 μm, and the length of the long side is 200 μm. The gap between the auxiliary light source openings 23 is 92 in the short side direction.
μm and 100 μm in the long side direction.
It is distributed so as to correspond to the distribution of 5, 46. The second flattening layer 48 is made of an acrylic resin and has a thickness of about 2 μm. The color filters 41, 42, and 43 have a stripe shape, and have a width of about 85 μm and a gap of about 15 μm. As the color filters, a red color filter 41, a green color filter 42, and a blue color filter 43 are sequentially arranged. The red color filter 41 is close to the red color conversion layer 44, the green color filter 42 is close to the green color conversion layer 45, and the blue color filter 43 is close to the blue color conversion layer 46. are doing. The third flattening layer 49 is made of an acrylic resin and has a thickness of about 2 μm. In addition, the first planarizing layer 47, the second planarizing layer 48, and the third planarizing layer 49 may be made of an epoxy resin.
The common electrode 16 is made of ITO and has a layer thickness of 0.2 μm. As the second alignment film 14, a polyimide organic polymer manufactured by Nissan Chemical Industries, Ltd. was used in the same manner as the first alignment film 13. The first alignment film 13 and the second alignment film 14 are subjected to an alignment treatment by a rubbing method, so that the first alignment film 13
Between the liquid crystal layer 10 and the second alignment film 14 is 240
Rotated by degrees. Color conversion layer 4 on second substrate 12
4, 45, 46, the auxiliary light source opening 23, and the color filters 41, 42, 43, the color conversion layers 44, 45, 46 and the color filter 4, as shown in FIG.
The stripes 1, 42, 43 are parallel to each other, and the color conversion layers 44, 45, 46 and the auxiliary light source opening 23
And the gaps between the color filters 41, 42, and 43 are distributed so as to overlap when viewed from the substrate normal direction of the second substrate 12. Accordingly, light from the auxiliary light source 50 located below the second substrate 12 passes through the color conversion layers 44, 45, and 46,
It can be guided further above.

Next, the two substrates 11 and 12 were assembled so that both alignment films 13 and 14 faced each other.
In order to make the distance between the two substrates uniform and to make the thickness of the liquid crystal layer uniform over the entire display portion, a spacer and a seal portion were formed therebetween. The spacer is a spherical polymer bead having a diameter of 7 μm and dispersed throughout the display unit. The dispersion density was about 100 per 1 cm ² . The seal portion was formed by applying a mixture of spherical polymer beads to an epoxy resin around the display portion.
The alignment marks of the first substrate 11 and the second substrate 12 are appropriately arranged, and the alignment marks are used to use the alignment marks.
2, the color conversion layers 44, 45, 4
6 and the stripes of the color filters 41, 42, 43 were arranged in parallel to the pixel electrode 17. The color conversion layers 44, 45, and 46 overlap the pixel electrode 17, the color filters 41, 42, and 43 overlap the pixel electrode 17, and the auxiliary light source opening 23 is formed of the inclined layer 32 when viewed from the substrate normal direction.
The distribution overlaps with one of the slopes.

The liquid crystal layer 10 includes an anthraquinone-based and diamine-based dichroic dye 2, a chiral agent S811 manufactured by Merck, and a liquid crystal composition MLZ479 manufactured by Merck.
A mixture of 2 was used. The weight ratio of S811 was about 0.9%. The liquid crystal layer 10 was formed by vacuum sealing from the sealing opening.
MLZ4792 is a high-resistance liquid crystal composition having a positive dielectric anisotropy and capable of active driving. This liquid crystal material is sealed between the first substrate 11 and the second substrate 12 by a vacuum sealing method. Thus, a liquid crystal layer 10 was formed. Note that one of the liquid crystal layers 10 represents a liquid crystal molecule.

In a state where the auxiliary light source 50 is not turned on,
The liquid crystal display was irradiated with white light, and the dependence of the reflectance on the applied voltage was measured with the gate open. As shown in FIG. 4, the negative applied voltage dependency was obtained, and the threshold voltage at which the reflectance started to increase was about 2.7V. When the effective value of the applied voltage is 1 V, the reflectance is 5.4%,
The reflectance at V was 20.2%, and a 3.7: 1 contrast ratio was obtained by driving between the two voltages. Thereafter, the planar light source was disposed behind the second substrate 12, the driving circuit for the planar light source and the driving circuit for the liquid crystal layer were connected, and a reinforcing metal frame was provided to obtain a liquid crystal display device.
As the auxiliary light source 50, a light source mainly emitting blue light was used.
The light source that emits blue light includes an organic electroluminescence (EL) element, an inorganic EL element, a cold cathode tube including only a blue phosphor, and the like, and these are applicable. It has a structure in which an anode, a hole injecting layer, a hole transporting layer, a light emitting layer, an electron transporting layer, and a cathode are sequentially laminated, and has a light emitting layer obtained by adding a distilaryleneamine derivative to a distilarylene derivative. It emits blue light when a voltage of 5 V is applied, and its brightness is about 80 cd / m ² . Since the anode is made of ITO and is transparent, it emits light toward the anode. The anode is the second substrate 12
The auxiliary light source 50 is arranged so as to be close to. Here, in order to convert the color (wavelength) of light to a color on the short wavelength side corresponding to higher energy, a nonlinear optical material is required, but the conversion efficiency is low and a bright display cannot be obtained. In contrast, in the present embodiment, by using the auxiliary light source 50 that emits blue light having high energy among visible light, the color conversion layers 44, 45, and 46 made of phosphors are used to efficiently use red, green, and the like. Can be converted to other colors, and a bright display can be obtained.

Next, when an AC electric field having a frequency of 60 Hz and an effective voltage of 10 V was applied to the auxiliary light source 50, blue light was emitted toward the second substrate 12. FIG. 3 shows an optical path of light reaching the user when the auxiliary light source is turned on. For comparison, FIG. 3 shows an example of the optical path of reflected light that enters from outside and reaches the user when the auxiliary light source is not turned on. The external incident light 65 is reflected by the second reflection plate 22 toward the user, and has one reflection process on the optical path, whereas the auxiliary light source light 61 has two reflection processes. The blue auxiliary light source light passes through the auxiliary light source opening 23 after being changed in wavelength by the color conversion layer 43, is reflected by the first reflective plate 21, then enters the second reflective plate 22, and After being reflected by the reflection plate 22, the light goes to the user. The red color conversion layer 44 is close to the pixel provided with the red color filter 41, and the first reflector 21 on which the light passing through the red color conversion layer 44 is incident changes the normal of its reflection surface to the red color. It faces the filter 41 side. Therefore, the light that has passed through the red color conversion layer 44 and turned red can be selectively guided to the pixel including the red color filter 41. The same applies to green light and blue light. When the auxiliary light source was turned on, the display could be read even in a dark environment such as a dark room. The dependency of the reflectance on the applied voltage when the auxiliary light source 50 was turned on was also negative as in the case of no lighting, and the threshold voltage was about 2.7 V. The contrast ratio at that time was 2.9:
1, which was almost the same as the value measured when white light was irradiated from the outside. Brightness of bright display is 11 cd / m2
Met. In addition, red, green,
The hue of blue display was measured. International Lighting Institute 19
When plotted in the 31XYZ color system, as shown in FIG. 5, when the auxiliary light source was turned on, the distribution was farther away from the plot of the light source light, and a more vivid color display was obtained. In FIG. 5, reference numeral 81 denotes a color specification range when the auxiliary light source is not lit, 82 denotes a color specification range when the auxiliary light source is lit, and 83 denotes a color specification range when the conventional auxiliary light source is lit.

As described above, in the first embodiment, the plane light source that emits blue light is provided behind the second substrate 12,
This is converted to red, green, and blue light using a color conversion layer, and selectively guided to pixels having red, green, and blue color filters, respectively, to read a display in a dark environment. In addition to this, it was possible to expand the color specification range when the auxiliary light source was turned on.

FIG. 7 shows a second embodiment of the present invention.
The liquid crystal display device of the present embodiment is the first embodiment (FIG. 1)
A phase plate 35 and a third alignment film 15 were formed between the second alignment film 14 and the liquid crystal layer 10. The process of forming the phase plate 35 will be described below. First, the second alignment film 14 was formed by a spin coating method, and this was subjected to an alignment treatment by a rubbing method using a rubbing roll. Next, the second alignment film 14
Photopolymerizable liquid crystal molecules dissolved in a solvent such as xylene were applied on the substrate by using a spin coating method. Thereafter, the solvent is removed, and the photopolymerizable liquid crystal molecules are used as a liquid crystal layer.
. Since the photopolymerizable liquid crystal molecular layer was sufficiently thin, the alignment regulating force of the photoalignment film was applied to the entire layer, and the layer formed homogeneous alignment parallel to the direction defined by the photoalignment film. Thereafter, the polymer was irradiated with light and polymerized to form a phase plate 35 while maintaining the alignment direction. The light source has a wavelength of 360
A high-pressure mercury lamp having an emission line in nm is used.
J / cm ² , and the irradiation time was 5 minutes. By setting the thickness of the phase plate 35 to about 1 μ, the retardation is set to a quarter wavelength. Thereafter, a third alignment film 15 was formed by spin coating. As the photopolymerizable liquid crystal molecule, a liquid crystal molecule having an acrylic group at one or both molecular terminals was used. For the latter, see, for example, Dirk J. et al. Bro
er, Rifat A. M. Hikment,
Ger Challa et al. (Makromol.
Chem, Vol 190, 3201-3215
(1989)). In these photopolymerizable liquid crystal molecules, an acrylic group is photopolymerized to form a molecular main chain to form a polymer. In addition, a liquid crystal state can be obtained by having a mesogen portion in the center and further having a whole molecule in a rod shape.

As the third alignment film 15, a polyimide organic polymer manufactured by Nissan Chemical Industries was used as in the first and second alignment films 13 and 14. The third alignment film 15 was subjected to an alignment treatment by a rubbing method, and the alignment directions of the first alignment film 13 and the third alignment film 15 were made antiparallel. In addition, an alignment process was performed such that the alignment direction of the second alignment film 14 and the third alignment film 15 was 45 degrees. The liquid crystal material did not contain a chiral material. As described above, the liquid crystal layer 10 was set to the homogeneous alignment, and the angle between the alignment direction of the liquid crystal layer 10 and the alignment direction of the phase plate 35 was set to 45 degrees.

The vibration direction of the e-polarized light is directed by the dichroic dye 2 and thus is absorbed by the dichroic dye 2, but the vibration direction of the o-polarized light is perpendicular to the dichroic dye 2 and is therefore hardly absorbed. . By setting the angle between the retardation of the phase plate 35 and the alignment direction of the phase plate 35 with the alignment direction of the liquid crystal layer 10 as described above, incident light passes through the phase plate 35, is reflected by the second reflection plate 14, and is again reflected. In the process of passing through the phase plate 35, the e-polarized light and the o-polarized light in the liquid crystal layer 10 can be exchanged. Thereby, the two components of light in the liquid crystal layer 10 can both be sufficiently absorbed, and the contrast ratio can be improved. When the auxiliary light source was not lit, white light was irradiated, and the dependence of the reflectance on the applied voltage was measured with the gate open. As a result, as shown in FIG. 6, a negative applied voltage dependency was obtained. The reflectivity at the time of applying a voltage having an effective value of 1 V and 10 V was 3% and 17%, respectively. By driving between the two voltages, a contrast ratio of 5.7: 1 was obtained. The dependence of the reflectance on applied voltage when the auxiliary light source is turned on is negative as in the case of non-lighting, and the contrast ratio at that time is 8.1: 1, which is measured by irradiating white light from outside. The contrast ratio improved. The brightness of the bright display was 20 cd / m ² . The hue of red, green, and blue display when the auxiliary light source was not lit and when it was lit was measured. When the measurement results were plotted in the International Illuminating Engineering Institute 1931 XYZ color system, the distribution when the auxiliary light source was turned on was more distant from the plot of the light source light, and a more vivid color display was obtained.

As described above, in the second embodiment, the contrast ratio is increased by forming the phase plate 35 and the third alignment film 15 between the second alignment film 14 and the liquid crystal layer 10. Was completed. Further, by turning on the auxiliary light source 50, a higher contrast ratio and a wider color specification range than when the auxiliary light source 50 was not lit can be obtained.

A third embodiment of the present invention will be described. In this embodiment, the order of lamination of the color conversion layers 44, 45, 46, the second reflection plate 22, and the color filters 41, 42, 43 of the liquid crystal display device of the first embodiment (FIG. 1) is changed. The color conversion layers 44, 45, and 46 were disposed between the second reflection plate 22 and the color filters 41, 42, and 43. In this case, display characteristics almost similar to those of the first embodiment were obtained. Color conversion layers 44, 45, 46 and color filters 41, 42, 43
Is formed by patterning a binder to which a dye or a fluorescent substance is added by using a means such as photolithography. Because both are formed in a similar process,
It is efficient if formed continuously.

In the liquid crystal display device according to the third embodiment, since the color conversion layer and the color filter are directly laminated and both can be formed continuously, the second substrate 12 can be manufactured with higher efficiency. Having. The color conversion layer 4
The same effect can be obtained even if the order of lamination of the color filters 41, 42, 43 and the color filters 41, 42, 43 is reversed.

A fourth embodiment of the present invention will be described. In the present embodiment, the unevenness forming layer 20 is formed by pressing in the liquid crystal display device of the third embodiment. The concave-convex forming layer 20 is formed by forming a pressing die in which the concave and convex are inverted, and after applying an acrylic resin on the second substrate 12, the pressing die is pressed to form the concave-convex forming layer 2.
0 was set. In this case, display characteristics almost similar to those of the first embodiment were obtained. In the liquid crystal display device according to the first embodiment, the concavo-convex forming layer 20 is formed using photolithography. However, if the pressing process is used, it can be formed in a shorter time and with fewer steps. However, if a relatively soft layer such as a color conversion layer exists under the unevenness forming layer 20 as in the liquid crystal display device of the first embodiment, it is not preferable because the layer is deformed during stamping. By arranging the second reflection plate 22 so as to be closest to the second substrate 12 as in the present embodiment, it is possible to more easily form the unevenness forming layer 20 by pressing. The same effect can be obtained even if the order of laminating the color conversion layer and the color filter is reversed.

FIG. 8 shows a fifth embodiment of the present invention.
In the liquid crystal display device of the first embodiment (FIG. 1), the thickness of the liquid crystal layer is made uniform by using polymer beads. However, in the present embodiment, except for this, the liquid crystal layer 10 of the second substrate 12 is used instead.
The columnar protrusion 33 was formed on the side close to the. Further, the inclined layer 32 on the first substrate 11 was removed. The columnar projections 33 have a trapezoidal cross section, and are distributed such that one of the slopes thereof coincides with the auxiliary light source opening 23. Aluminum is vapor-deposited on the slope on the auxiliary light source opening 23, and its layer thickness is 20 mm.
0 μm, and the aluminum layer functions as the first reflector 21.

FIG. 9 shows an optical path of light reaching the user when the auxiliary light source is turned on. For comparison, FIG. 9 also shows an example of the optical path of the reflected light 66 that enters from outside and reaches the user when the auxiliary light source is not turned on. The auxiliary light source light 61 is used for the color conversion layer 4.
After the wavelength is changed at 4, 45, and 46, the light passes through the auxiliary light source opening 23, is reflected by the first reflector 21 formed on the columnar projection 33, and then enters the second reflector 22; After being reflected by the second reflector 22, it is directed to the user. When the auxiliary light source is not lit, a negative applied voltage dependency is obtained,
When the effective value of the applied voltage is 1 V, the reflectance is 10%,
The reflectance at 10 V was 32%. Almost the same contrast ratio as that of the liquid crystal display device of the first embodiment was obtained. When the auxiliary light source was turned on, a contrast ratio of 2.5: 1 was obtained.

Since the first substrate 11 of the present embodiment has the same structure as the substrate with the active elements of the conventional transmission type liquid crystal display device, it can be manufactured without changing the manufacturing line or making capital investment. It has the feature of being. By combining this with the second substrate 12 having the configuration shown in FIG. 8 and the auxiliary light source 50, as in the liquid crystal display device of the first embodiment, a reflection type color whose color range can be expanded when the auxiliary light source is turned on. A liquid crystal display was obtained.

FIG. 10 shows a sixth embodiment of the present invention. In the present embodiment, a first polarizing plate 36 is arranged outside the first substrate 11 of the liquid crystal display device of the fifth embodiment (FIG. 8). Further, a second polarizing plate 37 and a third alignment film 15 were formed on the side of the second substrate 12 close to the liquid crystal layer 10. The dichroic dye 2 was not added to the liquid crystal layer 10. The first polarizing plate 36 includes G1220 manufactured by Nitto Denko Corporation.
DU was used. The second polarizing plate 37 was formed in the same manner as the phase plate 35 used in the second embodiment (FIG. 7).
However, in the phase plate 35 of the second embodiment, the solution of the photopolymerizable liquid crystal molecules is applied on the second alignment film 14, but in the present embodiment, the solution of the photopolymerizable liquid crystal molecules 1 and the dichroic dye 2 is used. Was applied. When the mixture of the photopolymerizable liquid crystal molecules 1 and the dichroic dye 2 is formed into the liquid crystal layer 10 by removing the solvent, the dichroic dye 2 is oriented along the liquid crystal layer 10 to impart anisotropy to light absorption. To form a polarizing plate. At this time, the orientation direction of the dichroic dye 2 is the absorption axis, and the vertical direction is the transmission axis. First alignment film 13
The third alignment film 15 was subjected to an alignment treatment by a rubbing method. Also, to prevent the occurrence of reverse tilt domain,
To the liquid crystal layer 10 was added an optically rotating substance S811 manufactured by Merck at a ratio of 0.1% by weight. As described above, the liquid crystal layer 1
0 is a homeotropic alignment when a voltage is applied, and is a twisted alignment when no voltage is applied. The torsional orientation when no voltage was applied was rotated 90 degrees counterclockwise from the first substrate 11 to the second substrate 12.

FIG. 11 shows a transmission axis direction 71 of the first polarizing plate 36, a transmission axis direction 72 of the second polarizing plate 37, an alignment processing direction 73 of the first alignment film 13, and a third alignment direction. The relationship of the orientation direction 74 of the film 15 is shown. FIG. 11 is a view as seen from the normal direction of the substrate. The alignment processing direction 73 of the first alignment film 13 and the transmission axis direction 71 of the first polarizing plate 36 are parallel to each other. The orientation processing direction 74 and the transmission axis direction 72 of the second polarizing plate 37 were set to be parallel to each other. Also,
The alignment processing direction 73 of the first alignment film 13 and the third alignment film 1
The orientation direction 74 of No. 5 was set to 90 degrees. Since the orientation direction 74 of the third alignment film 15 is parallel to the longitudinal direction of the columnar projections 33, the fibers sufficiently contact the surface of the third alignment film 15 during the alignment process by the rubbing method, and the presence of the pixel electrode 17 A sufficient orientation treatment could be applied to the entire portion to be formed.

By arranging the various axial directions as shown in FIG. 11, a negative display can be obtained both when the auxiliary light source is not lit and when the auxiliary light source is lit. When the auxiliary light source is not lit, the light mainly enters from the normal direction of the substrate, passes through the normal direction of the substrate again after reflection, and travels toward the user. When the liquid crystal alignment is twisted during voltage application,
Like a twisted nematic liquid crystal display device, it serves as a wave guide, and a bright display is obtained. Further, when no voltage is applied, a dark display is obtained because the transmission axis directions of the first polarizing plate 36 and the second polarizing plate 37 are orthogonal to each other. When the auxiliary light source is turned on, the light passes through the second polarizing plate 37 once before entering the liquid crystal layer 10 and becomes linearly polarized light.
The light passes through the inside of the columnar projection 33 until the light enters the column 1, and since the columnar projection 33 is optically isotropic, the polarization state is maintained. Even in the process of traveling from the first reflector 21 to the second reflector 22, light passes through the inside of the columnar projection 33, so that the light similarly enters the second reflector 22 while maintaining the polarization state. . Thereafter, a negative display is obtained in the same manner as when the auxiliary light source is not lit.

When the auxiliary light source is not lit, the effective value of the applied voltage is 1
The reflectance at V was 1.3%, the reflectance at 10 V was 18.2%, and a contrast ratio of 14: 1 was obtained. When the auxiliary light source was turned on, a contrast ratio of 11: 1 was obtained. By using a polarizing plate to perform display according to the same principle as that of a twisted nematic liquid crystal display device, the contrast ratio could be increased. Further, since the first substrate 11 of the present embodiment has the completely same structure as the substrate with the active element of the conventional transmission type liquid crystal display device, it can be manufactured without changing the manufacturing line or making capital investment. is there. A reflective color liquid crystal display device having a higher contrast ratio and capable of expanding the color specification range when the auxiliary light source is turned on was obtained.

FIG. 12 shows a seventh embodiment of the present invention. In the present embodiment, a microlens array 86 is arranged between the second substrate 12 and the auxiliary light source 50 in the liquid crystal display device of the first embodiment (FIG. 1). The microlens array 86 has a substantially semi-cylindrical shape and a distribution extending parallel to the auxiliary light source opening 23. The pitch of the microlens array 86 was equal to the pitch of the pixels, and the center of the arc of the microlens array 86 was located at the auxiliary light source opening 23. Thus, the light emitted from the auxiliary light source 50 was focused on the auxiliary light source opening 23. When the brightness when the auxiliary light source was turned on was measured in a dark room,
45 cd / m ^2, which is more than four times higher than the case where the microlens array 86 is not used.

FIG. 13 shows an eighth embodiment of the present invention. In the present embodiment, a microprism array 87 is arranged between the second substrate 12 and the auxiliary light source 50 in the liquid crystal display device of the first embodiment (FIG. 1). The cross-sectional shape of the microprism array 87 was a substantially right-angled triangle and had a distribution extending parallel to the auxiliary light source opening 23. The width of the base of the right triangle was about 30 μm. Due to the refraction on the surface of the microprism array, the auxiliary light source light 61 is directed in a direction inclined with respect to the normal to the substrate plane. Further, except for the inclined layer 32 on the first substrate, the reflection surface of the first reflection plate 21 was made parallel to the plane of the first substrate 11. In addition, the auxiliary light source opening 23 on the second substrate 12 was arranged to be shifted by 5 μm with respect to the first reflection plate 21 on the first substrate 11. Since the auxiliary light source light 61 travels in a direction inclined with respect to the normal to the substrate plane, the auxiliary light source opening 23 is shifted from the first reflection plate 21 and passes through the auxiliary light source opening 23. Light enters the first reflector 21,
Further, the light was selectively incident on the pixel of the corresponding color.

When the display characteristics when the auxiliary electrode was turned on and when it was not turned on were measured, almost the same characteristics as those of the liquid crystal display device of the first embodiment were obtained. The use of the microprism array 87 eliminates the need for a gradient layer and allows the first substrate 11
Was able to have the same structure as that of the conventional substrate with the active element of the transmission type liquid crystal display device. In this case, the first substrate 11 can be manufactured without changing the manufacturing line or investing in equipment, and is used to display the color when the auxiliary light source is turned on, similarly to the liquid crystal display device of the first embodiment. A reflective color liquid crystal display device capable of expanding the range was obtained.

FIG. 14 shows a ninth embodiment of the present invention. In the present embodiment, a microprism array 87 having a curved inclined surface is arranged between the second substrate 12 and the auxiliary light source 50 in the liquid crystal display device of the first embodiment. The cross-sectional shape of the microprism array 87 has a repeating structure composed of a linear short side and a curved long side.
And a distribution extending in parallel to. The pitch of the repeating structure was equal to the pitch of the pixels. Since the side closer to the auxiliary light source 50 in the curve of the repeating structure has a small inclination, the auxiliary light source light 50 passes substantially in the normal direction of the substrate. Since the inclination of the curve increases as the distance from the auxiliary light source 50 increases, the auxiliary light source light is directed in a direction more inclined with respect to the normal direction of the substrate. Due to the refraction on the curved surface, the auxiliary light source light 61 is directed mainly in a direction inclined with respect to the normal of the substrate plane, and the auxiliary light source opening 2 is formed.
3. Further, except for the inclined layer 32 on the first substrate 11, the reflection surface of the first reflection plate 21 was made parallel to the plane of the first substrate 11. Since the first substrate 11 has exactly the same structure as the substrate with the active elements of the conventional transmission type liquid crystal display device, it can be manufactured without changing the production line for the transmission type liquid crystal display device and without capital investment. is there. In addition, the auxiliary light source opening 23 on the second substrate 12 was arranged to be shifted by 5 μm with respect to the first reflection plate 21 on the first substrate 11. Since the auxiliary light source light 50 is directed in a direction inclined with respect to the normal to the substrate plane, the light passing through the auxiliary light source opening 50 is arranged by displacing the auxiliary light source opening 50 with respect to the first reflecting plate 21. Incident on the first reflecting plate 21 and selectively incident on pixels of the corresponding color. 39cd when the brightness when the auxiliary light source is turned on is measured in a dark room
/ M ^2, which is more than three times that of the case where the microlens array 87 is not used.

Next, a tenth embodiment of the present invention will be described. In the present embodiment, the pixel electrode 17 on the first substrate 11 is used as the first reflector 21 except for the aluminum layer on the columnar protrusion 33 in the liquid crystal display device of the sixth embodiment (FIG. 10). . Further, similarly to the liquid crystal display device of the ninth embodiment (FIG. 14), a microprism array 87 having a curved inclined surface is arranged between the second substrate 12 and the auxiliary light source 50, and the second substrate 12 The upper auxiliary light source opening 23 was arranged to be shifted by 5 μm with respect to the first reflection plate 21 on the first substrate 11. When the brightness when the auxiliary light source was turned on was measured in a dark room, it was 39 cd / m ^2.
Is improved to three times or more as compared with the case where no is used. The contrast ratio was 14: 1 when the auxiliary light source was not turned on, and 10: 1 when the auxiliary light source was turned on.

Here, a description will be given of a comparative example with respect to the liquid crystal display device according to the first embodiment. As Comparative Example 1, the tilt direction of the first reflection plate 21 in the liquid crystal display device of the first embodiment was set to the opposite direction to that of the first embodiment. In this case, the auxiliary light source light passing through the red color conversion layer 44 was reflected by the pixel having the green color filter 42.
Similarly, the auxiliary light source light that has passed through the green color conversion layer 45 is reflected by the pixel having the blue color filter 43, and the auxiliary light source light that has passed through the blue color conversion layer 46 is a pixel having the red color filter 41. Was reflected in. The brightness when the auxiliary light source was turned on was measured in a dark room and found to be 3 cd / m ² or less. This is because the color of the light converted by the color conversion layer does not match the color of the light transmitted by the color filter, so that the auxiliary light source light was absorbed by the color filter. As a result, the brightness when the auxiliary light source was turned on was significantly reduced. As Comparative Example 2, the arrangement order of the color conversion layers in the liquid crystal display device of the first embodiment was changed, and the red color conversion layer 44 and the green color conversion layer 45 were replaced. In this case, the auxiliary light source light passing through the red color conversion layer 44 was reflected by the pixel having the green color filter 42.
Similarly, the auxiliary light source light passing through the green color conversion layer 45 was reflected by the pixel having the red color filter 41. When the brightness when the auxiliary light source was turned on was measured in a dark room, 4 cd
/ M ² or less. This is because the color of the light converted by the color conversion layer does not match the color of the light transmitted by the color filter, so that the auxiliary light source light was absorbed by the color filter. As a result, the brightness when the auxiliary light source was turned on was significantly reduced. As Comparative Example 3, the auxiliary light source 50 in the liquid crystal display device of the first embodiment was changed to emit red light. When the display state when the auxiliary light source was turned on was observed in a dark room, only red was observed, and neither blue nor green was observed. Since red has low energy among visible lights, it is not converted into another color in the color conversion layer made of a fluorescent material, and blue and green cannot be obtained.

[0033]

As described above, according to the present invention,
By providing the auxiliary light source, a display can be read even in a dark environment such as a dark room, and a thin and lightweight reflective liquid crystal display device can be realized. In addition, by turning on the auxiliary light source, not only the brightness but also the color purity of the display color can be improved. Further, since the auxiliary light source of the present invention has no interface with air, the interface reflection is extremely small, and the auxiliary light source irradiates from the portion where no electrode is present behind the liquid crystal cell, so that the aperture ratio is high and the auxiliary light source , Good display characteristics can be obtained.
Further, in order to convert the color (wavelength) of light to a shorter wavelength color corresponding to higher energy, a nonlinear optical material is required, but the conversion efficiency is low and a bright display cannot be obtained. However, in the present invention, by using an auxiliary light source that emits blue light having high energy among visible lights, it can be converted to other colors such as green and red with high efficiency by using a color conversion layer made of a phosphor, A bright display can be obtained. The auxiliary light source is distributed over the entire back surface of the second substrate, but the auxiliary light source light is distributed using a microlens array to distribute the auxiliary light source opening to a part of the non-pixel portion of the second substrate. If the light is collected in the light source opening, the auxiliary light source light can be guided to the auxiliary light source opening with higher efficiency, and a brighter display can be obtained. The color purity of the auxiliary light source light that has passed through the color conversion layer is determined by the shape of the emission spectrum of the phosphor contained in the color conversion layer, and the color purity is comparable to that of a color filter for a transmission type liquid crystal display device. Or more. Further, the red color conversion layer is arranged close to the red color filter, and the normal of the reflection surface of the first reflector is inclined toward the red color filter, so that the red color conversion layer is formed. The passed auxiliary light source light is selectively applied only to the pixel having the red color filter, so that when the auxiliary light source is turned on, a display having substantially the same color purity as the transmissive liquid crystal display device can be obtained. The same applies to green light and blue light.
Further, since the auxiliary light source is disposed behind the liquid crystal cell, the surface reflection by the auxiliary light source does not increase and the display characteristics do not deteriorate, and the opening of the auxiliary light source is located at the same position as the non-pixel portion of the second substrate. However, even though the auxiliary light source opening and the first reflector are added as new components, the ratio of pixels in the display unit hardly decreases, and thus, even when the auxiliary light source is not turned on. High reflectivity is obtained,
In a bright environment such as outdoors, a liquid crystal display with low power consumption and good display can be obtained.

[Brief description of the drawings]

FIG. 1 is a sectional view of a liquid crystal display device according to a first embodiment of the present invention.

FIGS. 2A and 2B are views of a first substrate viewed from a normal direction of the substrate in a liquid crystal display device of the present invention, and a view showing a state in which a pixel electrode is formed on an inclined layer;

FIG. 3 is a diagram showing an optical path of light reaching a user when the auxiliary light source is turned on in the first embodiment of the present invention.

FIG. 4 is a diagram showing display colors according to the first embodiment of the present invention.

FIG. 5 is a diagram illustrating a hue measured when the auxiliary light source is not lit and when the auxiliary light source is lit according to the first embodiment of the present invention

FIG. 6 is a diagram showing the applied voltage dependence of the reflectance of the liquid crystal display device of the present invention.

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

FIG. 8 is a sectional view of a liquid crystal display according to a fifth embodiment of the present invention.

FIG. 9 is a diagram showing an optical path of light reaching a user when an auxiliary light source is turned on according to a fifth embodiment of the present invention.

FIG. 10 is a sectional view of a liquid crystal display according to a sixth embodiment of the present invention.

FIG. 11 is a view showing various axial directions of a liquid crystal display device according to a sixth embodiment of the present invention.

FIG. 12 is a diagram showing a cross section of a liquid crystal display device according to a seventh embodiment of the present invention and an optical path of light reaching a user when an auxiliary light source is turned on.

FIG. 13 is a view showing a cross section of a liquid crystal display device according to an eighth embodiment of the present invention and an optical path of light reaching a user when an auxiliary light source is turned on.

FIG. 14 is a diagram showing a cross section of a liquid crystal display device according to a ninth embodiment of the present invention and an optical path of light reaching a user when an auxiliary light source is turned on.

[Explanation of symbols]

1: liquid crystal molecules, 2: dichroic dye, 10: liquid crystal layer, 11:
A first substrate, 12: a second substrate, 13: a first alignment film,
14: second alignment film, 15: third alignment film, 16: common electrode, 17: pixel electrode, 20: unevenness forming layer, 21: first reflector, 22: second reflector, 23: Auxiliary light source opening, 25: active element, 26: signal wiring, 27: scanning wiring, 28: drain line, 29: anti-reflection layer, 31:
Insulating layer, 32: inclined layer, 33: columnar projection, 35: phase plate, 36: first polarizing plate, 37: second polarizing plate, 41:
Red color filter, 42: green color filter, 4
3: blue color filter, 44: red color conversion layer, 45:
Green color conversion layer, 46: blue color conversion layer, 47: first planarization layer, 48: second planarization layer, 49: third planarization layer,
50: auxiliary light source, 86, 87: micro prism array

Continued on the front page F-term (reference) 2H091 FA01Y FA14Y FA29Z FA44Z FB04 FC10 FC24 FC26 FC29 FC30 FD04 FD06 FD14 FD24 GA03 GA13 HA08 HA18 LA11 LA15 LA18 LA30 5C094 AA08 AA10 AA48 BA03 BA43 CA19 CA24 DA03 EB03 ED04 ED14 FA01 FA02 5G435 AA03 AA04 BB12 BB16 CC09 CC12 DD10 EE26 FF03 FF05 FF07 FF12 FF14 GG12 GG25

Claims (5)

[Claims] 1. A liquid crystal cell comprising a first substrate, a second substrate, a liquid crystal layer, an auxiliary light source, and a driving device. The first substrate and the second substrate hold the liquid crystal layer to form a liquid crystal cell. A liquid crystal display device comprising a device connected to a first substrate and a second substrate, wherein the first substrate and the second substrate on the side close to the liquid crystal layer are provided with voltage applying means, wherein the first substrate is a liquid crystal display. The first substrate has a first reflector on the side adjacent to the layer, the second substrate has a second reflector and a color conversion layer on the side closer to the liquid crystal layer, and the second reflector is on a non-pixel portion. An auxiliary light source opening is provided, the auxiliary light source is located behind the liquid crystal cell and close to the second substrate, and the auxiliary light source is incident on the first reflector after passing through the color conversion layer and the auxiliary light source opening. And thereafter, the light is incident on a second reflection plate. 2. The color conversion layer according to claim 1, wherein the color conversion layer is red, green,
It consists of a color conversion layer having a blue emission color, and light emitted from each color conversion layer selectively enters a second reflector corresponding to a different pixel, and each pixel includes a color filter, and a color filter is provided. The filter is composed of color filters having red, green and blue transmitted light colors, the red color filter is distributed close to the red color conversion layer, and the green color filter is distributed close to the green color conversion layer. A liquid crystal display device wherein the blue color filter is distributed close to the blue color conversion layer. 3. The device according to claim 1, further comprising an inclined layer between the first reflecting plate and the first substrate, wherein a normal of a reflecting surface of the first reflecting plate is a first normal along the inclined surface of the inclined layer. A liquid crystal display device characterized by being inclined with respect to a normal line of a substrate. 4. The first substrate or the second substrate according to claim 1, wherein the first substrate or the second substrate has a columnar projection on a side close to the liquid crystal layer, the columnar projection has an inclined surface, and a part of the inclined surface is A liquid crystal display device having a metal layer that overlaps with an auxiliary light source opening and functions as a first reflector. 5. The liquid crystal display according to claim 1, further comprising a microlens array between the second substrate and the auxiliary light source, wherein the microlens array focuses the auxiliary light source light on the auxiliary light source opening. apparatus.