JP2002006304A - Liquid crystal device and electronic instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem of optical scattering efficiency differing corresponding to respective colors caused by dispersion of fine particles with equal variance in radii for the respective colors in dispersing the fine particles in a color filter, which in turn results in color difference accompanying variation in an observing angle and in deterioration of display quality because it is impossible to display with a color intended by the designer. SOLUTION: An optical scattering layer enabling an observer to observe the same color even when observed from a different angular direction is manufactured by adjusting average radii of the fine particles dispersed in the color filter for each color so as to equalize the optical scattering efficiency of the respective colors in respective main wavelength of transmitted light. Also a transparent resin film for flattening is optionally formed on a surface of the color filter concurrently serving as the optical scattering layer. Furthermore, the transparent resin film is optionally the optical scattering layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device for forming an image by applying a voltage to a liquid crystal material held between substrates.
Also, the present invention relates to an electronic device using the liquid crystal device, and more specifically, to an optical scattering layer of the liquid crystal device.

[0002]

2. Description of the Related Art A liquid crystal device performs display by controlling the polarization direction of incident light. Such liquid crystal devices include a reflective liquid crystal device using light incident from the front of the device, a transmissive liquid crystal device using light incident from the back or side of the device, a reflective liquid crystal device and a transmissive liquid crystal device. A transflective liquid crystal device having both functions of a liquid crystal device can be roughly classified into three types.

These liquid crystal devices generally have a layer that scatters emitted light in order to widen a range in which an image displayed by the liquid crystal device can be viewed, that is, a viewing angle.

As a conventional method of forming such an optical scattering layer, a method in which a resin and fine particles having a different refractive index are kneaded and dispersed in a resin, and the surface of the substrate is coated by a spin coater method, a roll coat method or the like. After coating and curing the entire surface, a method of patterning and forming a necessary portion may be mentioned.

In order to perform color display, a color filter is generally formed. Further, fine particles having a different refractive index from the color filter are dispersed in the color filter, so that the color filter itself is formed. It can have a scattering function.

[0006]

However, even if the particles have the same radius of dispersion, the scattering efficiency varies depending on the wavelength of the scattered light. For this reason, the efficiency of the scattered light is different for each color of the color filter, and there is a problem that a display in a color intended by a designer cannot be performed depending on an observation angle, and display quality is impaired.

The present invention has been made in view of the above-mentioned circumstances, and an object thereof is to provide a bright and easy-to-view display in which the hue does not change depending on the viewing angle even when the scattering efficiency of the optical scattering layer is increased. An object of the present invention is to provide a liquid crystal device and an electronic device having excellent quality.

[0008]

In order to achieve the above object, in a liquid crystal device according to the present invention, a liquid crystal is held between a pair of substrates, and an electrode is provided on at least one of the opposing surfaces of each substrate. A liquid crystal device, wherein an optical scattering layer in which fine particles having a different refractive index from the resin are dispersed in a colored resin is formed on at least one substrate, wherein the average radius of the fine particles is Is characterized by being different for each colored resin.

Here, in the present invention, it is preferable that a transparent resin film for flattening is formed on the surface of the optical scattering layer. According to this configuration, a color filter having a flat optical scattering layer can be manufactured, and high display quality can be obtained.

In particular, in such a configuration, it is desirable that fine particles having a different refractive index from that of the transparent resin be contained in the transparent resin. Thereby, higher scattering efficiency can be obtained.

Further, in the present invention, it is preferable that the optical scattering layer is formed on an opposing surface of at least one of the pair of opposing substrates. According to such a configuration, a clear display can be obtained without blurring the display.

Further, in the present invention, at least one of the pair of opposing substrates is provided on a surface outside the substrate.
A configuration in which the optical scattering layer is formed is desirable. With such a configuration, a bright and easy-to-view liquid crystal device can be stably supplied at low cost.

On the other hand, in the present invention, an optical reflection layer is formed on one surface of a lower substrate when viewed from the viewing side, of the pair of opposing substrates, and the optical reflection layer and a liquid crystal are formed. It is preferable that the optical scattering layer is formed between the layer and the layer. With such a structure, a liquid crystal device which uses external light effectively and has low power consumption can be provided.

Further, in the present invention, an optical reflection layer is formed on one of the surfaces of the pair of opposing substrates which is a lower side when viewed from the viewing side, and is viewed from the viewing side. A configuration in which the optical scattering layer is formed on any one surface of the upper substrate is also preferable. With such a configuration, a liquid crystal device that effectively uses external light and has low power consumption can be stably provided at low cost.

Further, in order to achieve the above object, an electronic apparatus according to the present invention is provided with the above liquid crystal device. According to the present invention, when forming the optical scattering layer, by optimizing the radius of the fine particles dispersed in the color filter for each color, the hue does not change depending on the viewing angle, and the display is bright and has high contrast. It is possible to obtain a screen.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) First, a passive-matrix driving type reflection type liquid crystal device according to a first embodiment of the present invention will be described. Here, FIG. 1 is a cross-sectional view showing the configuration of the reflection type liquid crystal device. In addition, in order to make each layer and each member in FIG. 1 a size recognizable on the drawing, the scale is different for each layer and each member.

First, in these figures, a liquid crystal cell 51 is shown.
A polarizer 60 containing a dichroic dye and retardation plates 66 and 65 are arranged on the front surface of the light emitting element. It should be noted that although there is a gap between the respective elements constituting the reflection type liquid crystal device, this is for convenience of illustration, and in actuality, the respective elements are substantially in close contact with each other. I have.

The external light that has passed through the polarizer 60 and has become linearly polarized light has become elliptically polarized light by passing through the retardation plates 66 and 65 and enters the liquid crystal cell 51. The polarization axis of the elliptically polarized light incident on the liquid crystal cell 51 is selected by the voltage applied to the segment electrode 11 and the common electrode 21, and is reflected by the optical reflection layer 15. The reflected light has its polarization axis selected by the applied voltage between the segment electrode 11 and the common electrode 21 and is incident on the phase difference plates 65 and 66, and the polarizer 60
Through. At this time, bright display and dark display can be selected according to the selected polarization axis. At this time, by passing through the optical scattering layer 43 twice, the incident external light is widely scattered and a bright display can be obtained.

Next, a more detailed structure and a manufacturing method of the liquid crystal cell 51 will be described.

First, a description will be given of a common electrode substrate which is an upper substrate (ie, an upper side in FIG. 1) as viewed from the viewing side. First, a 140 nm (1 nm) transparent conductor such as ITO is deposited on the second substrate 20 by an evaporation method or a sputtering method.
The common electrode 21 is formed with a thickness of 400 angstroms) and patterned by a photolithography method.

Next, a description will be given of a segment electrode substrate which is a lower substrate (ie, a lower side in FIG. 1) as viewed from the viewing side with reference to FIG. First, an optical reflection layer 15 made of aluminum having a thickness of 140 nm (1400 angstroms) is formed on the first substrate 10 by a sputtering method.

Further, a photosensitive organic film containing carbon black having a thickness of 2 μm is applied to the segment electrode substrate on which the optical reflection layer 15 is formed by a spin coating method. A pattern is formed, and a light-shielding layer 420 is formed.

Furthermore, a photosensitive acrylic resin containing a red, blue, and green colorant (refractive index: 1.47)
After kneading fine particles made of a silicon-based resin (refractive index: 1.38) having a different radius for each color at a weight ratio of 15%, the mixture is applied by a spin coating method, and optically scattered by a photolithography method. The color filters 411, 412, and 413 also serving as layers are formed, respectively.

Further, a transparent conductor such as ITO is formed to a thickness of 140 nm (1400 angstroms) by a vapor deposition method or a sputtering method, and is patterned by a photolithography method to form a segment electrode 11.

At this time, as the fine particles to be kneaded in the color filter, fine particles having different radii for each color were selected so that the scattering efficiency becomes equal at the wavelength of light passing through each color.

Here, (refractive index of resin) = 1.47,
(Refractive index of fine particles) = 1.38, 450n
The relation curves 207, 208, and 209 in FIG. 3 show how the scattering efficiency with respect to the particle radius changes at wavelengths of m, 550 nm, and 650 nm.

In FIG. 3, the particle radius at which the maximum scattering efficiency of 450 nm light can be obtained is 1.6 μm, and 550 n
The particle radii at which light having a wavelength of m and 650 nm can obtain the maximum scattering efficiency are 2.0 μm and 2.4 μm, respectively. For this reason, in the present embodiment, fine particles having a radius of 1.6 μm are kneaded with a blue color filter, and similarly,
Of fine particles is mixed with a green color filter and has a radius of 2.4.
The μm fine particles were kneaded with a red color filter.

Examples of the coloring agent contained in the photosensitive acrylic resin include oil dyes such as monoazo, disazo, metal complex, anthraquinone, phthalocyanine, and triallylmethane, which are conventionally used, and carbon black. , Titanium oxide, zinc white, inorganic pigments such as zinc sulfide, and monoazo, disazo, phthalocyanine,
Organic pigments such as quinacridone type are exemplified. For example, colorants for blue (B), green (G), and red (R) frequently used in liquid crystal devices include (B) phthalocyanine blue, (G) phthalocyanine green, and (R) brilliant carmine, respectively. No.

Then, after applying an alignment film to the opposing surfaces of the segment electrode substrate and the common electrode substrate manufactured by the above-described method and performing a rubbing process, the segment electrode 11 and the common electrode 21 are perpendicular to each other. The two substrates 10 and 20 are bonded together via a sealant 31, a liquid crystal material 50 is sealed in a space between the two substrates, and then sealed with a sealant to obtain a liquid crystal device.

The hue of the liquid crystal device thus manufactured does not change depending on the viewing angle. For this reason, the color expression of the liquid crystal device is not impaired.

In this embodiment, the optical scattering layer 43 is used.
Although the first substrate 10 is disposed on the surface facing the second substrate 20, the first substrate 10 may be disposed between the second substrate 20 and the retardation plate 65. Also, the optical scattering layer 43
May be provided between the common electrode 21 and the second substrate 20.

Further, the optical reflection layer 15 is formed on the first substrate 10
It may be arranged on the outer surface of the. At this time, the optical scattering layer 43 may be provided between the optical reflection layer and the first substrate.

In the present embodiment, the description has been made by taking a passive liquid crystal device driven by a matrix as an example.
(Thin Film Transistor) element and TFD (Thin Film Di
ode) It can also be used for an active matrix driving type liquid crystal device using elements or the like. Further, it may be a transmission type liquid crystal device.

(Second Embodiment) Next, a liquid crystal device according to a second embodiment of the present invention will be described. In this embodiment,
This is applied to an active matrix driven reflection type liquid crystal device capable of color display using a TFD element.

First, the TFD element 30 will be described with reference to FIGS.
1 will be described.

The TFD element 301 is formed on an insulating film 312 formed on a first substrate 310 as a base, and is formed on the first metal film 30 in order from the insulating film 312 side.
2, composed of an insulating layer 304 and a second metal film 306, and having a TFD structure (Thin Film Diode structure) or MI
It has an M structure (Metal Insulator Metal structure). The first metal film 302 of the TFD element 301 is connected to a wiring 311 serving as a data line or a scanning line formed on the first substrate 310, and the second metal film 306 is formed of an aluminum optical reflection. Metal electrode 330 also serving as layer
It is connected to the.

The insulating film 312 is made of, for example, tantalum oxide. Note that the insulating film 312 has a main purpose of preventing the first metal film 302 from peeling off from the base and preventing impurities from diffusing from the base into the first metal film 302 by a heat treatment performed after the deposition of the second metal film 306 or the like. Is formed. Therefore, if the first substrate 310 is made of a substrate having excellent heat resistance and purity, such as a quartz substrate, for example, and the separation and diffusion of impurities do not pose a problem, the insulating film 312 is omitted. can do. First
The metal film 302 is made of a conductive metal thin film, for example,
It is made of tantalum alone or a tantalum alloy. Insulating film 30
Numeral 4 is an oxide film formed by anodic oxidation on the surface of the first metal film 302 in a chemical solution, for example. Second metal film 30
Reference numeral 6 denotes a conductive metal thin film, for example, chromium alone or a chromium alloy.

Further, the metal electrode 330 and the TFD element 30
1. A transparent insulating film 303 is provided on the side facing the liquid crystal such as the scanning line 311 (that is, the upper surface in FIG. 5).

Next, a common electrode substrate on which color filters 411, 412, and 413 also serving as an optical scattering layer are formed will be described with reference to FIG.

First, a 2 μm-thick photosensitive organic film containing carbon black is applied on the second substrate 410 by spin coating, and then a 20 μm-wide pattern is formed by photolithography to form a light-shielding layer. 420 is formed.

Further, a photosensitive acrylic resin containing a red, blue, and green colorant (refractive index: 1.47)
Then, fine particles having different radii of epoxy resin (refractive index: 1.59) are kneaded at a weight ratio of 15%, then applied by spin coating, and an optical scattering layer is formed by photolithography. Color filter 41 also serves as
1, 412 and 413 are formed.

Further, a flattening film 4 in which fine particles having a refractive index different from that of the resin are dispersed in a transparent acrylic resin.
14 is applied to form an optical scattering layer 45. After flattening, a transparent conductive thin film made of ITO etc.
(1400 angstroms), and patterning is performed by photolithography to form an electrode 401 to be a scanning electrode or a data signal electrode.

At this time, as the fine particles kneaded in the color filters, fine particles having different radii of different radii for each color were selected so that the scattering efficiency becomes equal at the wavelength of light passing through each color.

Here, (refractive index of resin) = 1.47,
(Refractive index of fine particles) = 1.59, 450n
The relationship curves 210, 211, and 212 in FIG. 7 show how the scattering efficiency with respect to the particle radius changes at wavelengths of m, 550 nm, and 650 nm.

In FIG. 7, the particle radius at which 450 nm light can obtain the maximum scattering efficiency is 1.2 μm,
The particle radii at which light having a wavelength of m and 650 nm can obtain the maximum scattering efficiency are 1.5 μm and 1.8 μm, respectively. For this reason, in this embodiment, fine particles having a radius of 1.2 μm are kneaded with a blue color filter, and similarly,
Is mixed with a green color filter and has a radius of 1.8.
The μm fine particles were kneaded with a red color filter.

Colorants contained in the photosensitive acrylic resin include oil dyes such as monoazo, disazo, metal complex salt, anthraquinone, phthalocyanine, and triallylmethane based dyes which have been used. Examples thereof include inorganic pigments such as carbon black, titanium oxide, zinc white, and zinc sulfide, and organic pigments such as monoazo, disazo, phthalocyanine, and quinacridone. For example, colorants for blue (B), green (G), and red (R) frequently used in liquid crystal devices include (B) phthalocyanine blue, (G) phthalocyanine green, and (R)
Brilliant carmine.

Finally, the first substrate 310 and the second substrate 4
After applying an alignment film to the opposing surfaces of the substrate 10 and performing a rubbing process, the two substrates are arranged so that the wiring 311 and the electrode 401 are orthogonal to each other and the metal electrode 301 and the electrode 401 are opposite to each other. The liquid crystal material is sealed in the space between the two substrates by sealing the liquid crystal material into the space between the two substrates, and then forming a liquid crystal device.

The hue of the liquid crystal device thus manufactured does not change depending on the viewing angle. For this reason, the color expression of the liquid crystal device is not impaired.

Here, in the present embodiment, the optical scattering layer 45 is used.
Are arranged on the opposing surfaces of the pair of substrates, but may be arranged between the second substrate 410 and the retardation plate 65.

Further, the optical reflection layer 15 may be arranged on the outer surface of the first substrate. At this time, the optical scattering layer 45 may be provided between the optical reflection layer and the first substrate.

In this example, TFD (Thin Film Dio)
de) An explanation has been given using an active drive reflection type liquid crystal device using an element as an example, but a TFT (Thin Film Transistor) is used.
or) The present invention can be applied to an active matrix driving type liquid crystal device using elements and a passive driving liquid crystal device.
Further, it may be a transmission type liquid crystal device.

(Third Embodiment) FIG. 8 shows an example of an electronic apparatus according to the present invention. This is an electronic book, which is a kind of portable information terminal. Reference numeral 600 denotes an electronic book main body,
Reference numeral 601 denotes a liquid crystal display unit using the liquid crystal device of the present invention.

FIG. 9 shows a portable telephone as another example of the present invention. Reference numeral 605 denotes a mobile phone main body, and reference numeral 606 denotes a liquid crystal display unit using the liquid crystal device of the present invention. Since these electronic devices include the above-described liquid crystal device according to the present invention, they have a wide viewing angle, a bright display screen with high contrast, and a clear display screen.

[0054]

According to the present invention, the change in hue depending on the angle at which the liquid crystal device is observed can be reduced. Further, since the range of colors that can be expressed by the liquid crystal device is widened, the liquid crystal device can be rich in expressive power. Further, since the scattered light can be used effectively, a bright and high-contrast liquid crystal device can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a liquid crystal device according to a first embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of a segment electrode substrate in the liquid crystal device.

FIG. 3 shows the relationship between the refractive index of a fine particle = 1.38 and the refractive index of a transparent resin = 1.47, 450 nm, 550 nm, and 6 nm.
It is a graph which shows the relationship of the scattering efficiency with respect to a particle radius at the wavelength of 50 nm.

FIG. 4 shows a TF of a liquid crystal device according to a second embodiment of the present invention.
It is the top view which expanded D partly.

FIG. 5 is a partially enlarged sectional view of the TFD.

FIG. 6 is a partially enlarged cross-sectional view of a counter substrate of the liquid crystal device.

FIG. 7: 450 nm, 550 nm, 6 when the refractive index of the fine particles = 1.59 and the refractive index of the transparent resin = 1.47.
It is a graph which shows the relationship of the scattering efficiency with respect to a particle radius at the wavelength of 50 nm.

FIG. 8 is a perspective view illustrating an example of an electronic apparatus using the liquid crystal device of the present invention.

FIG. 9 is a perspective view illustrating another example of an electronic apparatus using the liquid crystal device of the present invention.

[Explanation of symbols]

 10, 20 ... substrate 11 ... segment electrode 21 ... common electrode 31 ... sealing material 32 ... sealing material 43, 45 ... optical scattering layer 50 ... liquid crystal material 51 ... liquid crystal cell 60 ... polarizer 65, 66 ... retardation plate 301 ... TFD elements 302, 306 metal films 310, 410 substrate 330 reflective electrodes 311 scanning lines 304, 312 insulating films 401 counter electrodes 411, 412, 413 color filters 420 black stripes 600 e-book body 601 Liquid crystal device 605: Mobile phone body 606: Liquid crystal device

 ────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Keiji Takizawa 3-3-5 Yamato, Suwa-shi, Nagano F-term in Seiko Epson Corporation (Reference) 2H042 BA02 BA14 BA20 2H048 BA02 BA45 BA47 BB01 BB02 BB10 BB44 2H091 FA02Y FA08X FA08Z FA11X FA11Z FA14Y FA14Z FA31X FA31Y FA34Y FB02 FB12 FC01 FD24 GA13 GA16 LA16 LA17

Claims (8)

[Claims] 1. A liquid crystal is held between a pair of substrates, an electrode is formed on at least one of opposing surfaces of each substrate, and at least one of the substrates has a plurality of colored resins, A liquid crystal device provided with an optical scattering layer in which fine particles having a different refractive index from the resin are dispersed, wherein an average radius of the fine particles is different for each of the colored resins. 2. The liquid crystal device according to claim 1, wherein a transparent resin film for flattening is formed on a surface of the optical scattering layer. 3. The liquid crystal device according to claim 2, wherein the transparent resin film contains fine particles having a refractive index different from that of the transparent resin film. 4. The liquid crystal device according to claim 1, wherein the optical scattering layer is formed on a facing surface of at least one of the pair of facing substrates. 5. The liquid crystal device according to claim 1, wherein the optical scattering layer is formed on a surface outside at least one of the pair of substrates facing each other. . 6. An optical reflection layer is formed on one of surfaces of a pair of opposing substrates which is a lower side as viewed from a viewing side, and an optical reflection layer is formed between the optical reflection layer and the liquid crystal layer. The liquid crystal device according to claim 1, wherein the optical scattering layer is formed on the liquid crystal device. 7. An optical reflection layer is formed on one surface of a lower substrate when viewed from the viewing side of the pair of opposing substrates, and the upper substrate when viewed from the observation side is formed. The liquid crystal device according to claim 1, wherein the optical scattering layer is formed on one of the surfaces. 8. An electronic apparatus comprising the liquid crystal device according to claim 1.