JP3006411B2 - Liquid crystal display - Google Patents

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. In particular, the present invention relates to an improvement that enables a light-weight, thin, and low-cost large-screen color display.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have been used everywhere, but small televisions and laptop personal computers.
As the market for display devices such as the like has expanded, the demands on the market have also become more sophisticated, and the display device has been rapidly evolving from monochrome images to color images and from small screens to large screens. Modules related to the prior art
Nocro liquid crystal display devices are made of a transparent conductive film made of ITO or the like.
The formed common electrode, thin film transistor and its
A plurality of pairs of pixel electrodes connected to the rain are formed on one surface.
Fills the gap between the transparent glass substrate and the liquid crystal
Voltage between the opposing common electrode and the pixel electrode.
To change the orientation of the liquid crystal and transmit or block light.
It is displayed in such a way that it is turned off. And the selected pixel
Displaying desired characters and images by applying voltage to electrodes
It is. Transmission type with polarizing plates on both sides of the liquid crystal display
And a polarizing plate on one side of the liquid crystal display device, and on the other side
There is a reflection type in which a reflection plate is provided. And the color LCD table
In the display device, each pixel has a red color filter.
A combination of a thin film transistor and a pixel electrode and a green color filter
Filter, thin film transistor, and pixel electrode
A combination of a color filter, a thin film transistor, and a pixel electrode
And one of the colors
Have been. Then, the pixel electrode corresponding to the selected color is
Displays characters and images of the desired color by applying voltage.
is there.

[0003]

With the demand for a large screen for the liquid crystal display device, it is required to reduce the weight, thickness and cost as well as the screen size. As a solution, TF
The transparent substrate having T and the pixel electrode is a glass substrate, and TF
While ensuring the heat resistance of the substrate required for T formation,
It has been proposed that a transparent substrate having a counter common electrode be a lightweight and thin transparent film substrate. In this case, since the color filter layer has poor adhesion to the transparent film substrate,
The color filter layer is formed on the TFT and the pixel electrode. As a method therefor, a method advantageous for automation or mass production in which a color filter layer is transferred onto a TFT or a pixel electrode via an adhesive can be considered.
By the way, in this method, since the adhesive layer and the color filter layer are formed on the pixel electrode, the driving voltage applied between the pixel electrode and the opposing common electrode drops by the adhesive layer and the color filter layer, The voltage applied to the important liquid crystal layer is greatly reduced. In order to drive such a liquid crystal display device, it is necessary to increase the drive voltage so that the high voltage can be turned on and off, which impairs the benefits of using a transparent film substrate and a color filter layer by a transfer method.

An object of the present invention is to solve this problem. Most of the driving voltage applied between a pixel electrode and a common electrode is applied to a liquid crystal layer, and a light-weight, thin, low-cost liquid crystal is used. A display device is provided.

[0005]

An object of the present invention is to provide a thin film transistor.
(2) and a pixel electrode (3) connected to its drain.
In front of the transparent glass substrate (1), which is formed on one side
A combination of the thin film transistor (2) and the pixel electrode (3)
A color filter layer (5) on the adhesive layer (4)
It is transferred and formed on one surface of the transparent film substrate (7).
The opposed common electrode (8) is
Facing the layer (5), with a gap in between,
The gap is formed between the transparent glass substrate (1) and the transparent glass.
Sealed by the film substrate (7) and the sealing portion (9)
In addition, the liquid crystal display device in which the liquid crystal is filled in the gap is
Oite adhesive layer of said color filter layer (5)
(4) is achieved by a liquid crystal display device in which a ferroelectric substance is dispersed.

When the ferroelectric substance is barium titanate or titanate, it has a high dielectric constant, is free from optical problems, and is advantageous. In addition, the ferroelectric
The compounding ratio of the substance is 20% by weight based on the weight of the adhesive layer (4).
Percent to 90 weight percent
No. Further, the particle diameter of the ferroelectric substance is 0.3 μm or less.
If it is below, it does not hinder the transmission of visible light and is good
High transparency can be realized.

[0007]

In the liquid crystal display device according to the present invention, a ferroelectric substance such as barium titanate or titanate is dispersed in each of the color filter layer 5 and the adhesive layer 4. For this reason, the respective capacitances of the color filter layer 5 and the adhesive layer 4 are increased as compared with the case where the ferroelectric substance is not dispersed.

FIG. 2 is an equivalent circuit of a pixel of the liquid crystal display device. In FIG. 2, V is a driving voltage applied between the pixel electrode and the common electrode, and C _CF is a composite of a series circuit of the capacitance of the color filter layer 5 and the capacitance of the adhesive layer 4. is the capacitance, C _LC is the capacitance of the liquid crystal layer. The voltage V _LC applied to the liquid crystal layer is calculated from the equivalent circuit of FIG.

[0009]

V _LC = C _CF · V / (C _CF + C _LC ), and when the capacitance of each of the color filter layer 5 and the adhesive layer 4 increases, the ratio of the voltage applied to the liquid crystal layer also increases. I do. The dielectric constant, which is an important factor related to the capacitance, is about one digit for the color filter layer 5 and the adhesive layer 4, whereas it is about 1700 for barium titanate and about 500 for titanate. high. Since the compounding ratio of the ferroelectric substance is about 20% by weight in the color filter layer 5 and 20 to 90% by weight in the adhesive layer 4, almost all of the driving voltage applied between the pixel electrode and the common electrode is opposite. Was applied to the liquid crystal layer, and it was found that the driving voltage V did not require a high voltage, and that it could be sufficiently driven by a normal TFT.

When the particle size of the ferroelectric substance is set to 0.3 μm or less, which is shorter than the wavelength of visible light, it is possible to maintain good transparency without hindering transmission of visible light.

For this reason, since a transparent film substrate or a color filter layer formed by a transfer method can be employed, a light-weight, thin, and low-cost liquid crystal display device can be obtained.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a liquid crystal display according to an embodiment of the present invention will be described in more detail with reference to the drawings.

FIG. 1 is a view showing a main part of a cross section of a liquid crystal display device according to one embodiment of the present invention. In FIG. 1, reference numeral 1 denotes a transparent glass substrate made of Corning Glass 7059 or the like.
Reference numeral 2 denotes a TFT formed on the transparent glass substrate 1 using hydrogenated amorphous silicon, and at the same time, a wiring (not shown) to the TFT 2 is formed. Reference numeral 3 denotes a pixel electrode formed of a transparent conductive film (ITO) in a matrix on the transparent glass substrate 1 on which the TFT 2 is formed. Reference numeral 10 denotes a pixel electrode forming substrate including a transparent glass substrate 1, a TFT 2, and a pixel electrode 3.

Reference numeral 4 denotes an adhesive layer formed on the pixel electrode forming substrate 10, and reference numeral 5 denotes a color filter layer formed on the adhesive layer 4. These are manufactured by the following transfer method.

First, a color filter layer 5 composed of R, G, and B colored patterns having a thickness of about 1 μm and containing 20% by weight of barium titanate is formed on a pixel film 3 on a polyester film serving as a base of a transfer substrate. Acrylic adhesive formed at the same pitch, and containing 50% by weight of barium titanate and cured by a combination of light and heat, is added to a layer of 1-2 μm.
The adhesive layer 4 is formed by applying a thickness of m to form a color filter transfer substrate. At least 90% by weight of the dispersed barium titanate has a particle size of 0.3 μm or less. Since the particle size is 0.3 μm or less, which is shorter than the wavelength of visible light, good transparency can be maintained without obstructing transmission of visible light. Next, the color filter transfer substrate is positioned at a predetermined position on the pixel electrode forming substrate 10,
UV rays are irradiated from both sides in an atmosphere of ° C. Thereby, the adhesive layer 4 is adhered to the pixel electrode forming substrate 10, the polyester film serving as the base of the transfer substrate can be easily peeled off, and the transfer of the color filter layer 5 is completed.

Reference numeral 20 denotes a common electrode substrate in which a counter common electrode 8 is formed of a transparent conductive film on a transparent film substrate 7 having a thickness of 0.1 mm and made of a plastic film such as polyethersulfone, polycarbonate, polyarylate, or polyester. It is.

The pixel electrode forming substrate 10 and the common electrode substrate 20
Means that after a predetermined orientation process is performed, the sealing portion 9
Is sealed through. Reference numeral 6 denotes a liquid crystal, which is sealed between the pixel electrode forming substrate 10 and the common electrode substrate 20. Further, a polarizing plate (not shown) and a reflecting plate as necessary are arranged to complete the liquid crystal display device.

The adhesive layer 4 has no practical problem if the ferroelectric substance content is 20 to 90% by weight. Also,
As an example of the composition of the coating solution for forming the adhesive layer 4, a mixture of 50% by weight of an ultraviolet light / thermosetting adhesive and 50% by weight of barium titanate with a biscoat UV727 (manufactured by Osaka Organic Chemical Industry Co., Ltd.) can do. Further, the adhesive layer 4
As a condition for forming, a film is applied to a film thickness of 1 to 3 μm and irradiated with 80 to 150 mJ / cm ² by a high-pressure mercury lamp.
Post-baking may be performed at 100 to 110 ° C. for 20 to 30 minutes.

[0019]

As described above, according to the liquid crystal display device of the present invention, since the ferroelectric substance between the color filter layer and the adhesive layer is dispersed, the static electricity between the color filter layer and the adhesive layer is reduced. The electric capacity increases. For this reason, even if the color filter layer and the adhesive layer are disposed between the pixel electrode and the common electrode, the voltage drop between the color filter layer and the adhesive layer is small, and the voltage drop between the pixel electrode and the common electrode is small. Since most of the drive voltage applied to is applied to the liquid crystal,
There is no need to increase the driving voltage, and a normal TFT can be used. That is, since the color filter layer and the adhesive layer can be arranged between the pixel electrode and the opposing common electrode, the color filter layer is transferred to a pixel electrode forming substrate having a transparent glass substrate, and a transparent film substrate is used as the common electrode substrate. it can.

As described above, since the formation of the color filter layer by the transparent film substrate or the transfer method can be adopted, a light-weight, thin, and low-cost liquid crystal display device can be obtained.

[Brief description of the drawings]

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

FIG. 2 is an equivalent circuit of the liquid crystal display device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent glass substrate 2 Thin film transistor 3 Pixel electrode 4 Adhesive layer 5 Color filter layer 6 Liquid crystal 7 Transparent film substrate 8 Opposing common electrode 9 Seal part 10 Pixel electrode formation substrate 20 Common electrode substrate

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/1335 505 G02B 5/20 101 G02F 1/136 500

Claims (4)

(57) [Claims] 1. A thin film transistor (2) and its drain
A plurality of pairs with the pixel electrode (3) to be connected are formed on one surface.
The thin film transistor (2) of the transparent glass substrate (1)
A color filter layer on the set of
(5) is transferred via the adhesive layer (4),
Opposing common electrode (8) formed on one surface of a lum substrate (7)
Is opposed to the color filter layer (5),
The gap is provided with the transparent glass substrate.
The plate (1), the transparent film substrate (7), and the sealing portion (9)
It is more sealed, and the gap is filled with liquid crystal
In the liquid crystal display device, the color filter layer (5) and the adhesive layer (4) include:
A liquid crystal display device comprising a ferroelectric substance dispersed therein. 2. The liquid crystal display device according to claim 1, wherein the ferroelectric substance is barium titanate or titanate. 3. The composition of the ferroelectric substance according to claim 3, wherein
20% by weight to 90% by weight based on the weight of layer (4)
3. The method according to claim 1, wherein
Liquid crystal display device. 4. The ferroelectric substance has a particle size of 0.3 μm or less.
4. The method according to claim 1, 2 or 3,
Liquid crystal display device.