JPH10239681A - Liquid crystal display device and electronic equipment having the same - Google Patents

Abstract

(57) [Problem] To provide a technique capable of adjusting brightness and chromaticity in a liquid crystal display device provided with a color filter according to the situation of ambient light. A liquid crystal layer is sandwiched between a pair of substrates having electrodes on opposing inner surfaces, a color filter is disposed on one of the substrates, and a color filter is formed in a region where a plurality of color elements are formed. And an uncolored region.

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, and more particularly to a technique for improving display characteristics of a liquid crystal display having a color filter.

[0002]

2. Description of the Related Art As a conventional liquid crystal display device having a color filter, there is a liquid crystal display device having, for example, a sectional structure shown in FIG. The liquid crystal display device described here is of a transmissive type.

In this liquid crystal display device, the substrate 11 on the front side is
A color filter is formed on the inner surface by a colored layer 16 in which red, blue, green, and the like are arranged in a predetermined arrangement method, and a light-shielding layer (not shown) therebetween, and a color filter for flattening (not shown) is formed thereon. An overcoat layer and a transparent electrode 13 are formed. Further, an alignment film (not shown) is applied thereon and rubbed in a predetermined direction.

On the other hand, a transparent electrode 15 is also formed on the inner surface of the substrate 12 on the back side, and an alignment film (not shown) is applied thereon and rubbed in a predetermined direction.

The liquid crystal layer 18 is formed by bonding the substrate 11 and the substrate 12 together via a sealing material (not shown) and sealing liquid crystal in a region surrounded by the sealing material. In the case of using a liquid crystal that requires a polarizing plate for display, such as a TN type liquid crystal, the polarizing plate is attached to the outside of both the substrates 11 and 12. A light source such as a backlight (not shown) is installed outside the substrate 12.

In the liquid crystal display device configured as described above, the light incident from the substrate 12 on the back side is applied to the liquid crystal layer 1.
8, the electrode 13 and the electrode 1 are sequentially transmitted through the colored layer 16 and emitted from the substrate 11 on the front side.
5, a desired display can be performed by changing the optical characteristics of the liquid crystal layer 18 whose orientation is controlled by applying a predetermined voltage between the liquid crystal layer 18 and the liquid crystal layer 18.

On the other hand, when a liquid crystal display device is used as a reflection type, a reflection plate (not shown) is provided outside the substrate 12 instead of the backlight. In the thus configured reflective liquid crystal display device, light incident from the substrate 11 side sequentially passes through the coloring layer 16, the liquid crystal layer 18, and the substrate 12, and
Since the light is reflected by a reflection plate (not shown), passes through the liquid crystal layer 18 and the coloring layer 16 again, and is emitted from the front substrate, the optical characteristics of the liquid crystal layer 18 are the same as in the case of the transmission type. , A desired display can be performed.

[0008]

However, in a liquid crystal display device having a conventional color filter, the brightness and chromaticity of the display cannot be adjusted according to the state of ambient light. It determines the transmittance of the color filter, an important parameter that determines the brightness and chromaticity of the display,
It cannot be changed arbitrarily. Such a technique of adjusting brightness and chromaticity is required for a liquid crystal display device in order to obtain a display that is easy to see in various environments.

For example, in the case of a liquid crystal display device used as a transmissive type, even if the chromaticity is low in a bright environment such as outdoors,
The bright display is easier to see. Also, in a dark environment such as indoors, even if the display is slightly dark, the higher the chromaticity, the easier to see and the sharper the display.

In the case of a reflection type liquid crystal display device utilizing light coming from outside, the influence of the surrounding environment on the display quality is more remarkable. Contrary to the transmissive type, the reflective type makes it easy to see a display with high contrast and high chromaticity in a bright environment, even if the display is somewhat dark. Conversely, in a dark environment, a bright display is a condition for easy-to-view display even if the chromaticity is low.

However, in the configuration of the liquid crystal display device using the conventional technology, it is difficult to adjust such display characteristics according to the surrounding environment. This is because the transmittance characteristics of the color filters that determine the brightness and chromaticity of the display are uniquely determined for the display, and cannot be changed according to the situation.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the invention is to provide a liquid crystal display device having a color filter in which chromaticity and brightness are adjusted in a well-balanced manner according to the environment in which the display device is used. It is to constitute a technology that can do this.

[0013]

Means taken by the present invention to solve the above problems are as follows.

That is, according to the present invention, there is provided a liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates having electrodes on opposing inner surfaces, and a color filter is disposed on one of the substrates. , Wherein the color filter is formed by a region where a plurality of color elements are formed and an uncolored region. Therefore, more various displays of brightness and chromaticity can be performed using the uncolored area.

According to a second aspect of the present invention, a color element region and a non-colored region are arranged corresponding to each dot constituted by the electrodes formed on the inner surface of the substrate. Features.

Further, the present invention according to claim 3 is characterized in that a unit pixel is formed by combining a dot on which a color element is arranged and a dot on which an uncolored area is arranged. By forming a unit pixel by combining a dot having a color element and an uncolored dot in this manner, it becomes possible to change display brightness and color density according to the surrounding environment. For example, when a display with high chromaticity is required even when dark, the liquid crystal is controlled so that light is transmitted only through dots having color elements (colored layers), and light is not transmitted through uncolored (non-colored layers) dots. The liquid crystal may be controlled as described above. When bright display is required even if the chromaticity is low, the liquid crystal of each dot may be controlled so that light passes through both the dot with the colored layer and the dot without the colored layer.

The present invention described in claim 4 is characterized in that the area of each color element of the color filter is changed for each color element. By changing the area for each color element, the color can be adjusted appropriately.

The present invention described in claim 5 is characterized in that gradation display of a liquid crystal display device is performed using dots in which uncolored areas are arranged. Therefore, gradation display becomes easy.

According to a sixth aspect of the present invention, a reflection plate is disposed on a side of the back side substrate, which is in contact with the liquid crystal layer, of the pair of substrates. Therefore, a clear image without a double image can be obtained even in the reflection type.

The present invention described in claim 7 is characterized in that the reflector also serves as a pixel electrode. Therefore, since the reflection plate and the pixel electrode can be formed simultaneously, the manufacturing method is also facilitated.

The present invention described in claim 8 is characterized in that the liquid crystal layer is composed of liquid crystal molecules and a polymer, and the polymer is dispersed in the liquid crystal molecules. Therefore, there is no need to display using a polarizing plate, and a liquid crystal display device with a bright display can be obtained.

According to a ninth aspect of the present invention, the other substrate is provided with electrodes arranged in a matrix, and each electrode is provided with a switching element. . Therefore. Since the liquid crystal can be completely operated for each dot, a clear image can be obtained.

According to a tenth aspect of the present invention, the liquid crystal layer is composed of a polymer and liquid crystal molecules, and the polymer is dispersed in the liquid crystal molecules. With such a liquid crystal layer, a bright display can be obtained without using a polarizing plate.

Further, by mounting a liquid crystal display device on an electronic device, a display device with a bright display can be provided, so that an electronic device with good appearance can be provided.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a liquid crystal display device having a color filter according to the present invention will be described with reference to the accompanying drawings. In this embodiment, as shown in FIG. 4, a front substrate 21 made of a transparent glass substrate is used.
In addition, a liquid crystal display device in which a liquid crystal layer 28 is sealed between the substrate 22 on the back surface side is configured.

On the inner surface of the substrate 21 on the front surface side, a color filter is formed by arranging colored regions 26 such as red, blue and green in a predetermined manner. This color filter is formed, for example, as follows. First, a photosensitive pigment-dispersed resin is applied by a spin coating method, a roll coating method, a flexographic printing method, or the like, and a film is formed to a thickness of about 200 to 5000 angstroms. Next, 50-150
Prebaking is performed at 5 ° C. for 5 to 60 minutes, and exposure and development are performed using a mask having a desired shape, and patterning is performed into a desired shape.

Thereafter, post-baking is performed at 75 to 200 ° C. for 10 to 20 minutes to fix the colored layer. Such a process is repeatedly performed on, for example, the photosensitive pigment-dispersed resin of each of the red, blue, and green color components, and each colored dot region (unit region) 26 is sequentially formed. The region 27 having no coloring layer (uncolored region) may be formed, for example, by coating and patterning a transparent resin by the same method as the photosensitive pigment-dispersed resin, or may not be formed at all. I do not care. If necessary, such as when the colored layer is thick, it is necessary to form a transparent overcoat layer over the entire inner surface of the substrate 21 to reduce the step in the thickness direction. Although not shown, a light-shielding layer may be provided between dots as needed.

In adding a dot of a non-colored layer (non-colored), a method of providing one dot of a non-colored layer per one unit pixel 40 as shown in FIG. 2, for example, is considered. In this example, one unit pixel 40 is formed by three dots of red 36a, green 36b, and blue 36c having a coloring layer and four dots 37 of a non-coloring layer. In the figure, the four dots are shown to have the same area, but of course the area may be different for each dot, and the arrangement order and arrangement may be different. Further, the light-shielding layer 39 shown in FIG.

On the thus formed color filter, ITO (indium tin oxide) or the like is formed.
For example, stripe-shaped transparent electrodes 23 are formed in parallel, and an alignment film made of polyimide resin or the like is applied and formed on the surface thereof. Rubbing is performed on the alignment film in a predetermined direction.

On the other hand, on the inner surface of the substrate 22 on the back side,
A transparent electrode 25 made of TO (indium tin oxide) or the like is formed. The transparent electrode 25 may be formed, for example, in a stripe shape, or may be formed, for example, in a shape divided for each dot. When formed in the shape of pixel electrodes divided for each dot, each electrode (pixel electrode) is connected via a non-linear element such as a MIM (metal-insulator-metal) element or an active element such as a TFT (thin film transistor). , Are connected to on-board wiring (not shown).

In this embodiment, the liquid crystal layer 28 is of a TN (twisted nematic) type. T
Since the N-type liquid crystal requires a polarizing plate for display, the polarizing plate is attached to the outside of each of the front substrate 21 and the back substrate 22. A light source (not shown) is provided on the back side of the substrate.

In the liquid crystal display device configured as described above, for example, in a dark environment, non-colored dots are shielded from light, and display is performed using only the dots of the colored layer. In this case, although the transmittance of the display body decreases and the brightness of the display decreases, all the transmitted light passes through any of the coloring layers, so that a vivid display with high chromaticity can be performed. On the other hand, for example, in a bright environment, display is performed using uncolored dots. In this case, although the transmittance of the display device is increased and the display becomes bright, the chromaticity is low and the display becomes pale because the achromatic light which does not pass through the coloring layer is mixed.

Here, when performing display using uncolored dots, the uncolored dots themselves can be used to engrave the gradation, and the dithering can be performed in combination with the dots having other coloring layers. The gradation can be engraved by the tone method. Naturally, a combination of these two methods is also possible.

In the above example, a method of providing one uncolored dot for one unit pixel as shown in FIG. 2 has been described. There is also a method in which one uncolored dot is provided for a dot having a colored layer. In this case, as in the case of FIG. 2, there are no particular restrictions on the area, the arrangement, and the like. Further, the light-shielding layer may not be provided.

Next, an embodiment in which a liquid crystal display device having a color filter according to the present invention is used as a reflection type will be described. In the present embodiment, a polymer-dispersed liquid crystal that does not require a polarizing plate for display is used as a liquid crystal material to be used. Also in this embodiment,
As shown in FIG. 1, a liquid crystal display device having a liquid crystal layer 58 sealed between a front substrate 51 and a rear substrate 52 made of a transparent glass substrate is formed.

On the inner surface of the front-side substrate 51, a colored layer is formed by the method described in the embodiment relating to the transmission type. However, when a liquid crystal display device is used as a reflection type, light used for display passes through the colored layer twice, so that the average transmittance according to the wavelength of the colored layer is set to be higher than that used for the transmission type. Is preferable to obtain a bright display. In the case of the present embodiment, the average transmittance of each colored layer at a wavelength of 380 to 760 nm is set to 50.
Set between ５５55%. These can be adjusted by the thickness of the coloring layer, the concentration of the pigment used for the coloring layer, and the like.

As to the method of adding uncolored dots, as in the case of the transmission type, a method of providing one uncolored dot for one unit pixel as shown in FIG. A method of providing one uncolored dot for each dot is conceivable.

An overcoat (not shown) is formed on the color filter formed of the colored layer thus formed, and a transparent electrode 53 made of, for example, ITO (indium tin oxide) is formed on the color filter.
Are formed in parallel, and an alignment film made of a polyimide resin or the like is applied and formed on the surface thereof. Rubbing is performed on the alignment film in a predetermined direction.

On the other hand, C
A reflective electrode 55 made of a reflective metal such as r or Al is formed. The reflection electrode 55 may be formed, for example, in a stripe shape, or may be formed, for example, in a shape divided for each dot. When formed in a shape divided for each dot, each electrode is connected to a wiring on a substrate (not shown) via a non-linear element such as an MIM (metal-insulator-metal) element or an active element such as a TFT (thin film transistor). Connected.

As the liquid crystal layer 58, a polymer-dispersed liquid crystal capable of performing display without using a polarizing plate is used. As the polymer-dispersed liquid crystal, particularly, the liquid crystal molecules and the polymer monomer compatible in the liquid crystal cell are oriented in a predetermined horizontal direction, and the polymer monomer is polymerized and cured.
For example, it is preferable that the liquid crystal molecules and the polymer particles are mutually dispersed by photopolymerization and curing. In this case, for example, when an electric field is not applied, the orientation directions of the liquid crystal molecules and the polymer particles are aligned to be in a transparent state, and when an electric field is applied, only the liquid crystal molecules are oriented in the direction of the electric field, so that they are in a cloudy state. Note that twist alignment of liquid crystal molecules can be performed with a chiral material.

In addition to the polymer-dispersed liquid crystal, a liquid crystal display device which does not require the use of a polarizing plate for display includes a light transmission state and a light scattering state or a colored state by utilizing light scattering and coloring properties. Liquid crystal display method of performing display by state transition between, for example, a phase transition type display method using a phase transition between a cholesteric phase and a nematic phase, a method using a dynamic scattering mode of a liquid crystal, a display method by orientation dispersion and the like like,
Some displays are performed by various methods.

In the liquid crystal display device thus constructed, for example, in a bright environment, non-colored dots are set in a light-shielded state, and display is performed using only the dots of the colored layer.
In this case, although the transmittance (reflectance) of the display decreases, the brightness of the display does not decrease much because the light reflected by the display is strong. In addition, since all the reflected light passes through any of the coloring layers, a vivid display with high chromaticity is possible. On the other hand, in a dark environment, display is performed using uncolored dots. In this case, the transmittance (reflectance) of the display increases, so that a small amount of light can be used effectively. Therefore, although the decrease in the brightness of the display can be suppressed, the light that does not pass through the coloring layer is mixed, so that the chromaticity is reduced. Is low and the display is pale. However, in a reflective liquid crystal display device, in a dark environment, a bright display is easier to see even if the color is light.

FIG. 6 shows an electronic apparatus equipped with the liquid crystal display device of the present invention. FIG. 6A shows an example in which the liquid crystal display device is mounted on a mobile phone (1000). That is, a liquid crystal display device is provided as the display unit (1001) of the mobile phone. Therefore, since the liquid crystal display device with low power consumption and excellent display characteristics is mounted, the capacity of the battery of the mobile phone can be reduced. Note that the liquid crystal display device may be either a transmission type or a reflection type. However, in the case of a reflection type liquid crystal display device, since a backlight is not required, the power consumption is low and the liquid crystal display device is suitable for a mobile phone.

FIG. 6B shows an example in which the liquid crystal display device is arranged on a timepiece. Either case where a liquid crystal display device is used as the clock face or where the liquid crystal display device is arranged on the clock face is possible. Especially,
When a liquid crystal display device is overlaid on a dial, it goes without saying that the device is used as a transmissive liquid crystal display device. Also,
Since a liquid crystal display device that does not use a polarizing plate as in the present application is used as an electronic device, the display characteristics of the electronic device are excellent, and a display with good appearance can be obtained.

FIG. 6C shows a portable terminal (120).
This is an example in which a liquid crystal display device is used for the display unit (1206) of (0). Input with a portable terminal can be performed by using a keyboard (1202) or the like, or by arranging touch keys (not shown) on the surface of the display unit. Note that a CD is stored inside a housing (1204) for storing a keyboard and the like.
-Needless to say, a device such as a ROM is installed.

In addition to such electronic equipment, the liquid crystal display device of the present invention can be installed in a projector, and a high-definition display can be obtained.

[0047]

As described above, according to the present invention, it is possible to perform more various displays of brightness and chromaticity by using dots corresponding to uncolored areas.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an embodiment of a liquid crystal display device including a color filter according to the present invention. When used as a reflection type.

FIG. 2 is an example of a pixel array of a color filter used in a liquid crystal display device including a color filter according to the present invention. When one uncolored dot is provided for one unit pixel.

FIG. 3 is an example of a pixel array of a color filter used in a liquid crystal display device including a color filter according to the present invention. When one uncolored dot is provided for one dot.

FIG. 4 is a schematic view showing an embodiment of a liquid crystal display device provided with a color filter according to the present invention. When used as a transmission type.

FIG. 5 is a schematic diagram showing a liquid crystal cell structure in a conventional liquid crystal display device having a color filter.

FIG. 6 is a diagram showing an electronic device equipped with the liquid crystal display device of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 front substrate 12 back substrate 13 transparent electrode 15 transparent electrode 16 colored dot 17 uncolored dot 18 liquid crystal layer 21 front substrate 22 back substrate 23 transparent electrode 25 transparent electrode 26 colored dot 27 uncolored Dot 28 liquid crystal layer 36a dot with a red coloring layer 36b dot with a blue coloring layer 36c dot with a green coloring layer 37 dot with no coloring 39 light shielding part 40 unit pixel 51 front side substrate 52 back side substrate 53 transparent Electrode 55 Reflective electrode 56 Colored dot 57 Uncolored dot 58 Liquid crystal layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yutaka Tsuchiya 3-3-5 Yamato, Suwa City, Nagano Prefecture Inside Seiko Epson Corporation (72) Inventor Hidekazu Kobayashi 3-3-5 Yamato Suwa City, Nagano Prefecture Seiko Epson (72) Inventor Eiji Chino 3-3-5 Yamato, Suwa City, Nagano Prefecture Seiko Epson Corporation

Claims (11)

[Claims] 1. A liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates having electrodes on opposing inner surfaces, and a color filter is disposed on one of the substrates. A liquid crystal display device comprising a region in which elements are formed and an uncolored region. 2. A liquid crystal display according to claim 1, wherein a region of each color element and a non-colored region are arranged corresponding to each dot constituted by the electrodes formed on the inner surface of the substrate. apparatus. 3. The liquid crystal display device according to claim 1, wherein a unit pixel is formed by combining a dot on which a color element is arranged and a dot on which an uncolored area is arranged. 4. The liquid crystal display device according to claim 1, wherein the area of each color element of the color filter is changed for each color element. 5. The liquid crystal display device according to claim 1, wherein gradation display of the liquid crystal display device is performed using dots in which uncolored areas are arranged. 6. The liquid crystal display device according to claim 1, wherein a reflection plate is disposed on a side of the pair of substrates that is in contact with the liquid crystal of the rear substrate. 7. The liquid crystal display device according to claim 1, wherein said reflection plate also serves as a pixel electrode. 8. The liquid crystal display device according to claim 1, wherein the liquid crystal layer comprises liquid crystal molecules and a polymer, and the polymer is dispersed in the liquid crystal molecules. 9. The liquid crystal display device according to claim 1, wherein electrodes arranged in a matrix are formed on the other substrate, and a switching element is formed on each electrode. 10. The liquid crystal display device according to claim 1, wherein said liquid crystal layer comprises a polymer and liquid crystal molecules, and said polymer is dispersed in said liquid crystal molecules. 11. An electronic apparatus comprising the liquid crystal display device.