JPS6263918A - Liquid crystal element - Google Patents

Abstract

PURPOSE:To form a liquid crystal element having color picture elements of high transmittance by providing a protective layer having a specific coefft. of linear expansion between a color filter layer and transparent electrodes. CONSTITUTION:The color filter layers 14 which are respectively one picture element of a BGR color filter are provided on a substrate 11a and the transparent electrode 12a is provided via the protective layer 15 on said color filter layer 14. The protective layer 15 is exemplifed by a material selected from materials having the coefft. alpha of linear expansion most adequately 0.05-5 times the coefft. of linear expansion of the transparent electrode 12a. More specifically, SiO2 (alpha; 6X10<-6>/ deg.C) is suitable.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal device, and particularly to a color liquid crystal device suitable for a color display device.

[Conventional technology]

A liquid crystal element conventionally used in a liquid crystal color display device has a pixel formed by a counter electrode portion of a matrix electrode pattern and a liquid crystal located between them, and a color filter layer provided for each pixel. At this time, a method is adopted in which the color filter layer is disposed on the electrode forming the aforementioned pixel or between the electrode and the substrate. This color filter layer is colored blue (B) for each pixel.
The filters, green (G) filters and red (R) filters, are arranged in a striped shape and in a mosaic shape, and are formed by pixel-selective optical switching.
The video display and color screen 7'7" will be displayed.

[The invention solves the problem 1. However, the transmittance of the liquid crystal element used in conventional color display devices is low when the pixel is opened (J). I felt safe in Light.

Regarding the above-mentioned problem, after repeated studies, Mitsubishi et al. found that when forming ITO (indium tin oxide), which becomes a transparent electrode, on the color filter layer that constitutes the color pixel, , sputtering used for ITO film formation 1) Corona generation during puffing As a layer of protection for the oak filter layer, the color filter layer 1. A protective layer made of photo-curing +1 resin was provided on the 2000-2000, but this protective layer was heated to 200°C or more during sputtering, and
It was found that the critical surface between the protective layer and the ITO film was a rough or undulating non-uniform surface, and that this non-uniform surface was the cause of the low transmittance of the pixel when it was opened.

Therefore, an object of the present invention is to provide a liquid crystal element having color pixels with high transmittance.

[Means for Solving the Problem] and [Operation] The invention provides a liquid crystal element in which a liquid crystal is arranged between a pair of substrates, in which at least one of the pair of substrates has a color filter layer and the color filter. a transparent electrode provided on the layer, and a gap between the color filter layer and the transparent electrode of 0.00000 with respect to the linear expansion coefficient of the transparent electrode.
The liquid crystal element is characterized by having a protective layer having a linear expansion coefficient of 0.01 to 6.0 times.

〔Example〕

FIG. 1 shows an embodiment of a liquid crystal element that can be applied to a color display device, with FIG. 1(A) being a plan view thereof and FIG. 1(B) being a sectional view thereof. In the liquid crystal element shown in FIG. 1, a BGR color filter is arranged in a stripe shape for each pixel, and a scanning signal 152 is applied to the scanning line 1, and information 4 is applied to the display line 2 in synchronization with this scanning signal.
A color display can be obtained by applying a display signal such as No. 11 or a video signal.

The liquid crystal element of the present invention comprises a pair of substrates], la and 11.
A liquid crystal 16 is arranged between the substrates 11a4 and 2b (e.g. glass, plastic film), and a live transparent electrode ai12a (e.g. ITo).
are wired, and a striped transparent electrode 12b (for example, ITO) that becomes a scanning line 1 is wired on the substrate 11b.

Further, in the present invention, the substrate 11a is provided with a color filter layer 14 that becomes one pixel of the BGR color filter, and a protective layer 1 is provided on the side of the color filter layer 14.
5. 1) A transparent electrode 12a is provided.

Protective layer 15 used in the present invention and 1. The transparent electrode 12a
0.01 to 6 times, preferably 0.01 to 6 times the linear expansion coefficient of
．． Examples include those selected from those having a linear Il tensile coefficient (denoted by -α) of 0.01 to 5 times, most preferably 0.05 to 5 times. Specifically, 5i02(α, 6
X 10-7/'O), Ti02(α; 9 X 1
0-7/'C Riya glass (α; 45-100 X 10
Insulating inorganic substances such as -7/'O) or acrylic thermosetting resins (α; 200 to 300
/'C, silicone resin (α; 200~500X10-
710C) and polyimide resin (α, 400-500X1
A thermosetting resin such as 0-7/'O) is suitable.

These m expansion coefficients α are JIS (Shiraki Industrial Standard) K67
Based on measurements at 14. In addition, as the transparent electrode 12a used in the present invention, ITO (the coefficient of linear expansion differs depending on the mixing ratio of indium and tin,
Generally 80 x 10-7 to 100 x 10-7/
'O) is appropriate. In addition, indium oxide (approximately 4
0 x 10-77"O) and tin oxide (approximately 40 x 10-7
/'O) can also be used as a transparent electrode.

In the present invention, as will be made clear in the examples below, the linear expansion coefficient of the above-mentioned protective layer 15 is determined by the linear expansion of the transparent electrode formed thereon by a sputtering method (particularly a sputtering method at a substrate temperature of 200° C. or higher). 0.01 times to 6 for the coefficient
By multiplying the sputtering time by 200'
It was possible to prevent the surface roughening or waviness of the protective layer 15 caused by heating above C. The reason for this is not clear at present, but when the linear expansion coefficient of the protective layer 15 is increased, for example, by a factor of 6 or more, an ITO film is formed on the protective layer 15 under heating, and after the heating, it is rapidly cooled. As a result, the protective layer 15 undergoes a sharper contraction than the ITO film, and this contraction force is expected to cause the protective layer 15 to become rough or wavy.

Therefore, it is considered that by optimizing the coefficient of linear expansion of the protective layer 15, roughening or waviness of the protective layer 15 can be prevented.

In addition, 4 on top of the RGB color filter layer 1 used in the present invention.
Alternatively, a vapor-deposited layer of a pigment or dye or a film formed by containing a pigment or dye in a resin binder can be used.

On the transparent electrodes 12a and 12b described above, alignment control films 13a and 13 are formed with uniaxial alignment axes by rubbing treatment or the like.
b is formed. As the orientation control films 13a and 13b, films formed of polyimide, polyesterimide, polyamideimide, polyamide, polyvinyl alcohol, etc. are applicable, but in the present invention, in order to prevent color fading of the color filter layer 14 due to ultraviolet rays, Polyimide is suitable for the orientation control film 13a. In particular, by setting the thickness of the polyimide film to 0, 5 p, m or more, it is possible to cut out 50% or more of ultraviolet rays (wavelength of 350 nm or less). In addition, for polyimide, for example, N-methylpyrrolid is used as a solvent for the polyamic acid resin component that is its precursor, but if this solvent is applied directly to the color filter layer, the color filter layer will be eluted by this solvent. In addition, in the present invention, by forming the above-mentioned transparent electrode 12a on the color filter layer,
It has the effect of preventing the above-mentioned elution.

The liquid crystal 16 used in the liquid crystal element of the present invention can be selected from various types, but twisted nematic (TN) liquid crystal and ferroelectric liquid crystal are particularly suitable. In particular, the ferroelectric liquid crystal preferably has a bistable state. In other words, a ferroelectric liquid crystal in a bistable state is in a crossed nicol state when the angle (tilt angle) that is half of the angle between the first stable state and the second stable state is 22.5°. Although maximum transmittance and maximum light shielding rate can be obtained, the tilt angle in practice is generally about 5° to 15°. Moreover, as mentioned above, the protective layer formed on the conventional color filter layer was the cause of reducing the transmittance, so the color filter layer was not applied to the ferroelectric liquid crystal element, which exhibits a bistable state. When provided, the transmittance decreased significantly, and a good color pattern could not be displayed unless a very high brightness 7-channel light was used.

The above-mentioned ferroelectric liquid crystals include chiral smectic C phase (SmC'''') H phase (SmH'), I
phase (SmI'), phase (SmK') and phase G (SmG")
can be used.

In the present invention, this problem could also be solved by adjusting the linear expansion coefficients of the transparent electrode and the protective layer of the color filter layer as described above.

FIG. 2 is a sectional view showing another embodiment of the invention.

Figure 2 shows a substrate (glass?) 26 that makes up the display panel.
Drive thin film transistors (TFTs: Th1
nFi 1mTransistor).

TPT is a gate line (
(consisting of a transparent or metal thin film conductive film), a gate electrode 21 provided on the gate line, a thin film semiconductor 22 formed on the gate electrode 21-h via an insulating film 25, and a semiconductor source electrode 23 in contact with It consists of a source line (made of a conductive film) provided and a drain line provided at the other end of the semiconductor. The L drain electrode 24 constitutes a transparent electrode 29 which serves as a front small element.

Further, a color filter layer 27 and a protective layer 28 formed on the first part of the color filter layer 27 are provided on the substrate 26a at a location corresponding to the transparent layer pj129. As described above, the coefficient of linear expansion is set to 0.01 to 6 times, preferably 0.01 to 5 times, and optimally 0.05 to 5 times. Further, an alignment control film 20a made of polyimide having a -uniaxial alignment axis is provided on the [-] side of the transparent electrode 29.

A liquid crystal 31 is disposed between the TPT substrate 26a and a counter substrate 26b facing the opposite substrate, and a counter electrode 3 is provided on the counter substrate 26b.
2 is provided covered with a polyimide alignment control film 20b, and a liquid crystal 41 is provided around the TPT substrate 26a and the counter substrate 26b.
A sealing material 33 for sealing is provided.

FIG. 3 shows an embodiment in which the color filter layer 27 used in the liquid crystal element shown in FIG. 2 is disposed on a counter substrate 26b. In this case as well, the color filter layer 27 is made to correspond in position to the transparent electrode 29 via the protective layer 34, similar to the liquid crystal element shown in FIG.

Hereinafter, the present invention will be explained according to examples.

Example 1 First, a positive resist (trade name: 0FPR8) was applied onto glass (7059 manufactured by Konin Co., Ltd.) by a spinner coating method.
00, manufactured by Tokyo Ohka Chemical Co., Ltd.) was applied onto the pixel electrode to a film thickness of 5,000 to 7,000 layers. Next, after performing pre-beta at 90°C for 30 minutes, mask exposure was performed with ultraviolet light, immersion in a dedicated developer for 1 minute, and immersion in a dedicated rinsing solution for 1 minute to form a resist mask. Next, the entire surface of the photosensor array on which the resist mask was formed was exposed to light to make it soluble in a solvent. Next, the photosensor array and the copper phthalocyanine packed in the Mo boat were placed in a vacuum container, and the Mo port was heated to 450 to 550°C at a vacuum degree of 10-5 to 10-6 Torr to remove the copper phthalocyanine. Vapor deposition was performed, and the film thickness was 4. It was set to OOO. Thereafter, the resist mask was immersed and stirred in a developer exclusive for 0FPR to remove unnecessary portions of the deposited film while dissolving the resist mask, thereby forming a patterned old color filter layer. Subsequently, a similar 0FPR800 was applied to the photosensor array 7 on which this patterned blue dye layer was formed, and after exposure and development, a resist mask corresponding to the first patterned green dye layer was formed on the entire surface. After exposure, it was placed in a vacuum evaporator, and Pb phthalocyanine was then evaporated at 450 to 550°C to obtain a film of 3,000 layers.After that, it was immersed in a developer and stirred to form a patterned green color filter layer.

Furthermore, by using exactly the same process, Irgazine Red BP was produced as a red pigment based on perylenetetracarboxylic acid derivatives.
T (trade name: ClNo. 71127 manufactured by Chipa Geigy) was deposited at 400-500'C for about 3000 minutes, and treated with a developer to obtain a patterned red color filter layer.

Next, a film of 5i02 was formed to a thickness of 1000 nm on the glass substrate provided with the color filter layer described above by vacuum evaporation. When this 5i02 was measured according to JIS K6714, it was 6X10-7/°C. Next, add ITO to 5i0
A film was formed on the two films to a thickness of 100 mm by sputtering at a substrate temperature of 250°C. This ITO film JI
When measured with SK6714, it was 95×10-7/”O
Met.

When the ITO film surface of the ITO/5i02/color filter/glass plate prepared by the above method was measured using a universal surface shape measuring instrument rSE-3CJ manufactured by Koita Research Institute, no rough surface or waviness was observed. Furthermore, when we measured the transmittance, we found that it was 72% under white fluorescence (wavelength 400~
average transmittance at 600 nm).

Next, after patterning the ITO film of the substrate created above into a stripe shape, IOO was applied.

A human polyimide membrane (a 5% N-methylpyrrolidone solution of polyamic acid was applied and then dehydrated and ring-closed) was provided, and its surface was rubbed in one direction with a cloth.

In addition, 5 used when creating the above-mentioned substrate as a counter substrate.
The same method was used except that the i02 film and color filter layer were omitted.

Next, the cells were assembled so that the striped ITO films of the two substrates crossed each other, their rubbing directions were parallel, and the distance between the two substrates was 1.5 gm to create an empty cell.

By vacuum injection method from the injection port of this empty cell, P-
Desyloxybenzylidene-P'-amino-2-methylbutylcinnamate (DOBAMBC) was injected into an empty cell, sealed, and then slowly cooled to 70°C at a rate of 5°C/hour, showing bistability. A ferroelectric liquid crystal (chiral smectic C phase) was developed.

After arranging a pair of orthogonal Nicols on this liquid crystal element, a 30W white fluorescent lamp was turned on from behind through a diffuser-transmitting plate, and a driving voltage was applied to the liquid crystal element to display a bright color. Got the display.

Example 2 Instead of the 5i02 film (protective layer) of the color filter substrate used when creating the liquid crystal element of Example 1, a solvent-free thermosetting film containing a phenol novolac type epoxy resin and a tetraethylenepentanmine curing agent was used. A liquid crystal element was prepared in the same manner as in Example 1, except that a liquid adhesive was used, and then evaluated, and the same results as in Example 1 were obtained.

In addition, when the linear expansion coefficient of the cured film of the thermosetting adhesive/agent described above was measured in the same manner as in Example 1, it was found to be 480
It was 10-7/°C.

Comparative Example 1 In place of the 5i02 film of the color filter substrate used when creating the liquid crystal element of Example 1, an acrylic photocurable resin (c7 manufactured by Tsukiku Fine Chemical Co., Ltd.) Photolec was used.
A liquid crystal element was produced in the same manner as in Example 1, except that RFG) was used. The transmittance of the color filter substrate used when creating this liquid crystal element was 58%.

Furthermore, when the condition of the ITO film surface was measured using the surface profile measuring instrument used in Example 1, waviness with an average roughness of about 1 river was observed.

Example 1 The linear expansion coefficient of the cured film of this photocurable resin
When measured using the same method, the linear expansion coefficient was approximately 780.
X I O-7/°O.

Next, a liquid crystal element was prepared using this color filter substrate in the same manner as in Example 1, and a color display was performed, but the display was darker than that in Example 1.

Furthermore, by replacing the sputtering during ITO film formation with a low-temperature sputtering method below 100'O, we were able to prevent the waviness phenomenon that causes transmittance reduction. It was found that because the film was formed by low-temperature sputtering, the adhesion with the protective layer (cured film of photocurable resin) was poor, making it unsuitable for long-term use.

Example 3 When the liquid crystal element of Example 1 was prepared, a thermosetting acrylic resin (manufactured by Mitsubishi Rayon Co., Ltd., FR-3288) was used instead of the Si02 film (protective layer) of the color filter substrate used.
) was used, but a liquid crystal element was prepared in the same manner as in Example 1, and the same results as in Example 1 were obtained.

Furthermore, when the linear expansion coefficient of the cured film of the thermosetting acrylic resin was measured in the same manner as in Example 1, it was found to be 530.
X10-7 to 100×10-7/°C.

Comparative Example 2 In place of the Si02 film of the color filter substrate used when creating the liquid crystal element of Example 1, a thermoplastic styrene-methyl methacrylate copolymer resin (manufactured by Tetsu Kagaku Co., Ltd.,
The same method as in Example 1 except that MS 200) was used,
A liquid crystal element was created. The transmittance of the color filter substrate used in producing this liquid crystal element was 57%.

Furthermore, when the surface condition of the ITO film was measured using the surface profile measuring device used in Example 1, the result was -4! The undulations are approximately uniform and uniform. When the linear expansion coefficient of this heat and nf plastic resin coating was measured in the same manner as in Example 1, the linear expansion coefficient it gio xl, 0-
It was 7/'C.

〔Effect of the invention〕

Therefore, according to the present invention, in order to produce a color liquid crystal element rIII color filter substrate, a high temperature sputtering method of 200° C. or lower, which is excellent in adhesion, is applied.
It can be made into 1f function. That is, it is possible to prevent the rough surface or waviness of the color filter substrate that occurs during high-temperature rapid cooling, and as a result, the color transmittance in the catheter spray device can be improved by 40%.

[Brief explanation of drawings]

FIG. 1(A) is a first side view of the liquid crystal element f of the present invention.
Figure (B) is its AA sectional view. FIGS. 2 and 3 are cross-sectional views showing another embodiment of the liquid crystal element E of the present invention.

Claims (12)

[Claims] (1) In a liquid crystal element in which a liquid crystal is arranged between a pair of substrates, at least one of the pair of substrates has a color filter layer and a transparent electrode provided on the color filter layer, and . A liquid crystal element, comprising a protective layer having a linear expansion coefficient 0.01 to 6 times that of the transparent electrode between the color filter layer and the transparent electrode. (2) The protective layer has a linear expansion coefficient of 0.0 with respect to the linear expansion coefficient of the transparent electrode.
The liquid crystal element according to claim 1, having a linear expansion coefficient of 0.01 to 5. (3) The protective layer has a linear expansion coefficient of 0.
2. The liquid crystal element according to claim 1, having a coefficient of linear expansion of 0.05 to 5. (4) The liquid crystal element according to claim 1, wherein the protective layer is a layer obtained by forming a cured film of a thermosetting resin. (5) The liquid crystal element according to claim 1, wherein the protective layer is a coating made of an insulating inorganic substance. (6) The liquid crystal element according to claim 5, wherein the insulating inorganic substance is SiO_2. (7) The liquid crystal element according to claim 1, wherein the transparent electrode is a film formed by sputtering a mixture of indium oxide and tin oxide at a substrate temperature of 200° C. or higher. (8) The liquid crystal element according to claim 1, wherein the color filter layer is a coating formed with a pigment or dye by vapor deposition. (9) The liquid crystal element according to claim 1, wherein the color filter layer is a film formed by containing a pigment or dye in a resin binder. (10) The linear expansion coefficient of the transparent electrode is 40×10^-^
7 to 100×10^-^7/°C. The liquid crystal element according to claim 1. (11) The linear expansion coefficient of the protective layer is 2×10^-^7~
The liquid crystal element according to claim 1, which has a temperature of 6×10^-^5/°C. (12) The liquid crystal element according to claim 1, wherein the transparent electrode is coated with an alignment control film having a uniaxial alignment axis that has the effect of aligning the liquid crystal in one direction.