JP2003270630A - Liquid crystal display device and electronic appliance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device which enables a bright display having wide view angle. <P>SOLUTION: In this liquid crystal display device 10, a liquid crystal layer 40 is inserted between a pair of substrates 20, 30 which are opposed to each other, a reflection layer 22 composed of a hologram reflection layer and cholesteric reflection layer, etc., is formed on the counter substrate 20 and a light scattering layer comprising a forward scattering film 50 is disposed on the upper surface of an element substrate 30. <P>COPYRIGHT: (C)2003,JPO

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 an electronic device, and more particularly, to a liquid crystal display device suitable for use with a new type of reflector different from a conventional metal reflector such as a cholesteric reflector and a hologram reflector. Related to the configuration of.

[0002]

2. Description of the Related Art Reflective liquid crystal display devices have low power consumption because they do not have a light source such as a backlight, and have been widely used in various portable electronic devices and auxiliary display parts of devices. As a reflective layer of such a reflective liquid crystal display device, a metal film having a high light reflectance, such as aluminum or silver, has been conventionally used. On the other hand, in recent years, dielectric mirrors in which dielectric thin films having different refractive indexes are alternately laminated, cholesteric reflectors using cholesteric liquid crystals, hologram reflectors using hologram elements, and the like have been proposed.

Among them, cholesteric liquid crystals exhibit a liquid crystal phase at a certain temperature (liquid crystal transition temperature) or more, and in the liquid crystal phase, liquid crystal molecules have a periodic spiral structure with a constant pitch. This structure has a property of selectively reflecting light having a wavelength matching the pitch of the helix and transmitting other light. Furthermore, since the pitch of the helix can be controlled by the temperature at the time of orientation, the color of reflected light can be changed by changing the orientation temperature, and it is also used as a reflective color filter.

Further, the hologram element reflects the incident light in a direction deviated from the specular reflection direction according to the pitch of the interference fringes formed in the element, so-called off-axis (Off-axis).
Axis) function. Further, it is possible to reflect light of different wavelengths by changing the pitch of the interference fringes, and it can be used as a reflective color filter like the cholesteric liquid crystal.

These new-type reflectors have the above-mentioned peculiar functions, and can realize a display with high brightness and high color purity when compared with the reflection layer of a metal film which has been widely used in the past. Therefore, it is attracting attention as a technique capable of improving the display quality of a reflective liquid crystal display device.

[0006]

However, the above-mentioned reflector is not suitable when compared with the conventional reflective layer made of a metal film.
The problem is that the viewing angle is essentially narrow. That is, FIG. 7 shows a configuration example of a conventional reflective liquid crystal display device, in which the liquid crystal layer 1 is provided between the upper substrate 101 and the lower substrate 102.
03 is sandwiched, and a reflection layer 104 such as a cholesteric reflection layer or a hologram reflection layer is provided on the upper surface of the lower substrate 102. In this liquid crystal display device, the light L1 incident from above the upper substrate 101 causes the upper substrate 101 and the liquid crystal layer 10 to pass.
After passing through 3, the liquid crystal layer 1 is reflected by the reflective layer 104 and again
03, sequentially pass through the upper substrate 101 and reach the eyes of the observer. However, this type of reflective layer originally has the property that the directivity of reflected light is strong, and when the screen of a liquid crystal display device is viewed from a limited narrow angle range, it is much brighter than in the past. The display can be obtained, but it has a problem that it becomes dark immediately when the viewing position is changed.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a liquid crystal display device capable of obtaining a bright display at a wide viewing angle.

[0008]

In order to achieve the above object, in a liquid crystal display device of the present invention, a liquid crystal is sandwiched between a pair of substrates facing each other and reflected on one of the pair of substrates. A liquid crystal display device in which a layer is formed, wherein the reflective layer is a cholesteric reflective layer, and the other substrate side is the viewing side, and the light reflected by the reflective layer is scattered to the viewing side of the reflective layer. A light-scattering layer is provided.

Another liquid crystal display device of the present invention is a liquid crystal display device in which liquid crystal is sandwiched between a pair of substrates facing each other, and a reflective layer is formed on one of the pair of substrates. The reflecting layer is a hologram reflecting layer, the other substrate side is the viewing side, and a light scattering layer for scattering the light reflected by the reflecting layer is provided on the viewing side with respect to the reflecting layer. .

In the liquid crystal display device of the present invention, even when a reflective layer having a strong directivity of reflected light such as a cholesteric reflective layer or a hologram reflective layer is used, a light scattering layer is provided on the viewing side of the reflective layer. Since it is provided, the reflected light is scattered when passing through the light scattering layer, and the intensity distribution of the reflected light can be made gentler than before. As a result, a liquid crystal display device that can obtain a bright display over a wide viewing angle can be realized.

As a concrete form of the light scattering layer, a forward scattering film provided on the outer surface of the other substrate may be used as the light scattering layer, or it may be formed on the inner surface of the one substrate or the other substrate. Alternatively, an inner surface scattering layer obtained by mixing particles having a refractive index different from that of the constituent material of the layer in the light transmitting layer may be used as the light scattering layer. In particular, when the front scattering film is provided on the outer surface of the other substrate, the scattering function can be added to the conventional liquid crystal display device by a simple method.

Another liquid crystal display device of the present invention is a liquid crystal display device in which a liquid crystal is sandwiched between a pair of substrates facing each other, and a reflective layer is formed on one of the pair of substrates. The reflective layer is formed of a cholesteric reflective layer, the other substrate side is a viewing side, and the reflective layer is formed on the inner surface of the one substrate with unevenness.

Another liquid crystal display device of the present invention is a liquid crystal display device in which liquid crystal is sandwiched between a pair of substrates facing each other, and a reflective layer is formed on one of the pair of substrates. The reflective layer is formed of a hologram reflective layer, the other substrate side is the viewing side, and the reflective layer is formed on the inner surface of the one substrate with unevenness.

In addition to the structure in which the light-scattering layer is separately provided as described above, when the inner surface of one substrate is provided with an uneven shape and a cholesteric reflection layer or a hologram reflection layer is formed thereon, the reflection layer itself has a scattering function. Will be given. Therefore, similarly to the above, the intensity distribution of the reflected light can be made gentler than in the past, and a liquid crystal display device that can obtain a bright display over a wide viewing angle can be realized.

An electronic apparatus of the present invention is characterized by including the liquid crystal display device of the present invention. According to this configuration,
It is possible to realize an electronic device including a liquid crystal display unit having excellent visibility.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is an exploded perspective view of the reflection type liquid crystal display device of the present embodiment, and FIG. 2 is a sectional view showing a schematic structure of the reflection type liquid crystal display device.

In this embodiment, a TFT (Thin-Film Tr
An active matrix reflective liquid crystal display device using an ansistor) element as a switching element will be described. Further, in each drawing, in order to make each layer and each member recognizable in the drawing, the scale is different for each layer and each member. Also, in FIG. 2, electrodes, TFTs, wirings, and other layers for driving the liquid crystal layer are not shown.

The reflective liquid crystal display device 10 of the present embodiment
As shown in FIG. 1, it is roughly composed of an element substrate (other substrate) 30 and an opposite substrate (one substrate) 20 that are opposed to each other with a liquid crystal layer 40 (not shown in FIG. 1) interposed therebetween. . Of these two substrates, the element substrate 30 side is arranged so as to be the user side (viewing side).

As shown in FIG. 1, an element substrate 30 which constitutes the reflection type liquid crystal display device 10 of the present embodiment includes a translucent substrate body 31 such as a glass substrate and a TFT element formed on the surface thereof. 32, the pixel electrode 33 and the like as main components. More specifically, the liquid crystal layer 40 of the substrate body 31
On the side surface, a number of data lines 34 and a number of scan lines 3
5 are provided in a grid pattern so as to intersect with each other. TFTs are provided near the intersection of each data line 34 and each scanning line 35.
An element 32 is formed, and a pixel electrode 33 made of a transparent conductive material such as indium tin oxide (ITO) is connected via each TFT element 32. Element substrate 30
When the entire surface of the liquid crystal layer 40 side of the
3 are arranged in a matrix, and in the reflective liquid crystal display device 10, each pixel electrode 33 and a region in which a data line 34, a scanning line 35, and the like arranged so as to surround the pixel electrode 33 are formed in one area. It is one pixel 1.

On the other hand, the counter substrate 20 includes a substrate body 21 and
The reflective layer 22 is a hologram reflective layer formed on the surface of the liquid crystal layer 40 and a common electrode 23. A cholesteric reflection layer may be used instead of the hologram reflection layer. For example, by changing the pitch of the interference fringes in the hologram reflection layer and the pitch of the helix formed by the liquid crystal molecules in the cholesteric reflection layer depending on the location, it is possible to selectively reflect only the light of a specific wavelength. Instead, it can also function as a reflective color filter.

In the present embodiment, as shown in FIG. 2, a pair of substrates 2 which are opposed to each other with a liquid crystal layer 40 interposed therebetween.
Of 0 and 30, the forward scattering film 50 is attached to the outer surface (observer side) of the element substrate 30 arranged on the observer side. The forward scattering film 50 has a thickness of 25, for example.
˜30 μm, a large number of beads having a refractive index of about 1.4 and a particle size of about 4 μm dispersed inside an acrylic resin layer having a refractive index of about 1.48 to 1.49. It is generally used for a liquid crystal display part of a mold information device or the like.

In the liquid crystal display device 10 of the present embodiment, a reflective layer 22 having a strong directivity of reflected light, such as a hologram reflective layer or a cholesteric reflective layer, is used. Since the scattering film 50 is provided, the reflected light L2 is scattered as shown in FIG. 2, and the intensity distribution of the reflected light L2 can be made gentler than before. As a result, a liquid crystal display device that can obtain a bright display over a wide viewing angle can be realized. Moreover, since the viewing angle can be widened only by attaching the front scattering film 50 to the surface of the element substrate 30, the above effect can be easily obtained.

[Second Embodiment] The second embodiment of the present invention will be described below.
The embodiment will be described with reference to FIG.

FIG. 3 is a sectional view showing a schematic structure of the reflective liquid crystal display device of this embodiment. The basic structure of the reflective liquid crystal display device of this embodiment is the same as that of the first embodiment, and only the position where the light scattering layer is provided is different. Therefore, in FIG. 3, the same components as those in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

In the reflection type liquid crystal display device 60 of this embodiment, the element substrate 30 is arranged on the observer side as in the first embodiment, and the hologram reflection layer, the cholesteric reflection layer, etc. are provided on the counter substrate 20 side. Is formed on the reflective layer 22.
In the case of the present embodiment, as shown in FIG. 3, the inner surface scattering over is caused by mixing a large number of beads having a refractive index of about 1.6 in an acrylic resin having a refractive index of about 1.56 on the counter substrate 20. The coat layer 51 is formed. The formation position of the inner surface scattering overcoat layer 51 may be above or below the common electrode 23 as long as it is on the viewing side of the reflection layer 22. Further, it may be formed on the upper side of the liquid crystal layer 40, that is, on the inner surface side of the element substrate 30.

Also in the liquid crystal display device of this embodiment,
Since the inner surface scattering overcoat layer 51 is provided on the viewing side of the reflective layer 22 including a hologram reflective layer, a cholesteric reflective layer, etc., the intensity distribution of the reflected light L2 can be made gentler than in the conventional case, and a wide viewing angle can be obtained. It is possible to obtain the same effect as that of the first embodiment in that a bright liquid crystal display device can be realized.

[Electronic Equipment] Examples of electronic equipment equipped with the liquid crystal display device of the above embodiment will be described.

FIG. 4 is a perspective view showing an example of a mobile phone. In FIG. 4, reference numeral 1000 indicates a mobile phone main body, and reference numeral 1001 indicates a display unit using the above liquid crystal display device.

FIG. 5 is a perspective view showing an example of a wrist watch type electronic device. In FIG. 5, reference numeral 1100 indicates a timepiece body, and reference numeral 1101 indicates a display unit using the above liquid crystal display device.

FIG. 6 is a perspective view showing an example of a portable information processing device such as a word processor and a personal computer. In FIG. 6, reference numeral 1200 is an information processing apparatus, reference numeral 1202 is an input unit such as a keyboard, reference numeral 1204 is the information processing apparatus main body, and reference numeral 1206 is a display unit using the above liquid crystal display device.

Since the electronic equipment shown in FIGS. 4 to 6 is equipped with the liquid crystal display device of the above-described embodiment, it is possible to realize an electronic equipment equipped with a bright liquid crystal display section in a wide viewing angle.

The technical scope of the present invention is not limited to the above-mentioned embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the above-described embodiment, an example in which a light scattering layer is provided separately from the reflective layer is shown. However, after unevenness is formed on the surface of the substrate body on the counter substrate side by using a resin or the like, a hologram layer or a cholesteric layer is formed thereon. The reflective layer itself may be made to have a light scattering function by forming a reflective layer made of. With this configuration, the viewing angle can be widened.

Further, in the above embodiment, an example of the reflection type liquid crystal display device was shown, but a semi-transmissive reflection type liquid crystal display device can be constructed by forming the above-mentioned reflection layer into a half mirror. The present invention can be applied not only to the active matrix liquid crystal display device but also to a passive matrix liquid crystal display device.

[0035]

As described above in detail, according to the present invention, even when a reflective layer having a strong directivity of reflected light, such as a hologram reflective layer or a cholesteric reflective layer, is used, the light scattering layer is provided on the visible side. Is provided, the reflected light is scattered,
The intensity distribution of reflected light can be made gentler than before. As a result, it is possible to realize a bright liquid crystal display device over a wide viewing angle.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a schematic configuration of a reflective liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a schematic configuration of the reflective liquid crystal display device.

FIG. 3 is a sectional view showing a schematic configuration of a reflective liquid crystal display device according to a second embodiment of the present invention.

FIG. 4 is a perspective view showing an example of an electronic apparatus including the liquid crystal display device.

FIG. 5 is a perspective view showing another example of the electronic device.

FIG. 6 is a perspective view showing still another example of the electronic device.

FIG. 7 is a cross-sectional view showing a schematic configuration of a conventional reflective liquid crystal display device.

[Explanation of symbols]

10,60 Reflective liquid crystal display device 20 Counter substrate (one substrate) 22 Reflective layer 30 element substrate 50 Forward scattering film (light scattering layer) 51 Inner surface scattering overcoat layer (light scattering layer)

Continued front page    (72) Inventor Osamu Okumura             Seiko, 3-3-3 Yamato, Suwa City, Nagano Prefecture             -In Epson Corporation F term (reference) 2H042 AA02 AA11 AA26 BA02 BA12                       BA20 BA21                 2H091 FA14Y FA16Y FA32X FA32Y                       FB02 FD06 LA19 MA10

Claims (7)

[Claims] 1. A liquid crystal display device in which a liquid crystal is sandwiched between a pair of substrates facing each other, and a reflective layer is formed on one of the pair of substrates, wherein the reflective layer comprises a cholesteric reflective layer. The liquid crystal display device is characterized in that the other substrate side is a viewing side and a light scattering layer that scatters light reflected by the reflective layer is provided on the viewing side with respect to the reflective layer. 2. A liquid crystal display device in which liquid crystal is sandwiched between a pair of substrates facing each other, and a reflective layer is formed on one of the pair of substrates, wherein the reflective layer is a hologram reflective layer. The liquid crystal display device is characterized in that the other substrate side is a viewing side and a light scattering layer that scatters light reflected by the reflective layer is provided on the viewing side with respect to the reflective layer. 3. The liquid crystal display device according to claim 1, wherein the light-scattering layer is formed of a forward scattering film provided on the outer surface of the other substrate. 4. The light-scattering layer is formed on the inner surface of the one substrate or the other substrate, and particles having a refractive index different from that of the constituent material of the layer are mixed in the light-transmitting layer. The liquid crystal display device according to claim 1 or 2, comprising an inner scattering layer. 5. A liquid crystal display device in which a liquid crystal is sandwiched between a pair of substrates facing each other, and a reflective layer is formed on one of the pair of substrates, wherein the reflective layer comprises a cholesteric reflective layer. The liquid crystal display device is characterized in that the other substrate side is a viewing side, and the reflecting layer is formed on the inner surface of the one substrate with an uneven shape. 6. A liquid crystal display device in which liquid crystal is sandwiched between a pair of substrates facing each other, and a reflective layer is formed on one of the pair of substrates, wherein the reflective layer is a hologram reflective layer. The liquid crystal display device is characterized in that the other substrate side is a viewing side, and the reflecting layer is formed on the inner surface of the one substrate with an uneven shape. 7. An electronic apparatus comprising the liquid crystal display device according to claim 1. Description: