JPH0720476A - Liquid crystal device - Google Patents

Abstract

PURPOSE:To decrease birefringent index and to make red not appear even at low temperature by making a liquid crystal layer less in thickness at its outer peripheral part than at its display part. CONSTITUTION:Electrode layers 12a and 12b and orientation layers 13a and 13b are arranged on the surfaces of substrates 11a and 11b made of glass, plastic, etc. The couple of substrates 11a and 11b are arranged so that the orientation film surfaces face each other. Glass fiber pieces 15a and 15b are incorporated in scaling agents 14a and 14b for charging liquid crystal and the agents are stuck on the substrates by screen printing or by using a dispenser. In this case, the liquid crystal layer is uniform at the display part because of the scattering of many spherical powder, but there is a little spherical powder at a non-display part, so the liquid crystal is not held uniform and the non- display part becomes darker than the display part. Further, when the diameters of the glass fiber pieces 15a and 15b are made smaller than the spherical power between the substrates, the liquid crystal layer is made less in thickness at the outer peripheral part.

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 using a liquid crystal used in a system such as a computer terminal, an image display device and a shutter.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG.
Is a substrate made of glass, plastic or the like, on the surface of which electrode layers 52a and 52b and alignment film layers 53a and 53b are provided. The pair of substrates are installed so that the alignment film surfaces face each other. 54a and 54b are sealing agents for enclosing the liquid crystal, and the glass fiber pieces 5 are contained in the sealing agent.
5a and 55b are contained and attached on the substrate by screen printing or a dispenser, and 56 is a liquid crystal layer, 57
Reference numerals a, 57b, 57c are spherical powders made of glass or plastic sandwiched between the substrates in order to keep the thickness of the liquid crystal layer uniform, and 58a, 58b are polarizing plates. Reference numeral 59 is a reflector or a light source.

The thickness of the liquid crystal layer between the pair of substrates is determined by the diameter of the spherical powder and the glass fiber piece in the sealing agent, and the thickness of the liquid crystal layer is made uniform. In the conventional liquid crystal device, the liquid crystal layer is rubbed on the surface of the alignment film so that the liquid crystal layer has a twisted spiral structure of 240 ° twist, and the liquid crystal layer has a nematic liquid crystal having a positive dielectric anisotropy (Δε). A chiral agent was added. The thickness of the liquid crystal layer was 6 μm, and the product of the thickness of the liquid crystal layer and the refractive index anisotropy was 0.88 μm. The upper polarizing plate has chromaticity (x, y) = (0.284,
0.261) purple color polarizing plate (Nitto F10
25 VDU) and an ordinary polarizing plate (Nitto F
1025DU) was used.

FIG. 6 is a view showing the transmission axis direction of the polarizing plate and the rubbing direction of the alignment film. In FIG. 6, 61 is the rubbing direction of the alignment film on the upper substrate, 62 is the rubbing direction of the alignment film on the lower substrate, 63 is the transmission axis direction of the upper polarizing plate, 64 is the transmission axis direction of the lower polarizing plate, and 65 is The angle formed by the rubbing directions on the upper and lower substrates is 60 °, and 66 is the twist angle of the liquid crystal layer, which is 240.
The angle 67, the angle between the rubbing direction of the upper substrate and the transmission axis direction of the upper polarizing plate is 40 °, and the angle 68 is the angle between the rubbing direction of the lower substrate and the transmission axis direction of the lower polarizing plate 50 °.

FIG. 7 is a diagram for explaining the display portion of the liquid crystal device. FIG. 7 is a diagram when FIG. 5 is viewed from above. Reference numeral 71 denotes a portion in which a voltage is applied to the liquid crystal to change the contrast depending on the magnitude of the voltage value for display, and 72 denotes a portion to which no voltage is applied in the outer peripheral portion. As shown in FIG. 5, there is a portion to which no voltage is applied outside the display portion.

[0006]

A general liquid crystal display device is used within a range of approximately 0 ° C to 40 ° C. However, when a conventional liquid crystal display device is used at 25 ° C. (room temperature) and 0 ° C. (low temperature), there is a problem that the screen color of the liquid crystal device changes, the appearance deteriorates, and the display quality deteriorates. This problem will be described below.

Generally, at 25 ° C. (room temperature), the liquid crystal layer thickness and the liquid crystal refractive index are set so that the color of the liquid crystal device when the off voltage is applied and the color of the outer peripheral portion to which the voltage is not applied are almost the same. The anisotropy (Δn) and the angle of the polarizing plate are determined. The reason is that if the color of the outer peripheral part to which the voltage is not applied is different from the color of the part to which the off-voltage is applied, the part to which the voltage is not applied has a different color like a frame, and the appearance becomes worse. , By that.

However, at 0 ° C. (low temperature), the refractive index anisotropy of the liquid crystal increases, so in the conventional liquid crystal device, the color of the outer peripheral portion to which no voltage is applied becomes red, and the display portion and the outer peripheral portion are colored. There is a problem that the colors are different and the display quality is degraded. FIG. 8 is a diagram showing display colors in a conventional liquid crystal device. In FIG. 8, the color is represented by chromaticity (x, y),
81 indicates the direction of chromaticity x, and 82 indicates the direction of chromaticity y. In the conventional liquid crystal device, 1/64 duty, 1 / 9b
The ias and the driving voltage were set so that the contrast ratio became maximum in the normal direction of the liquid crystal device.

Reference numeral 83 represents the chromaticity when an ON voltage is applied,
Reference numeral 84 is a chromaticity when an off voltage is applied, 85 is a chromaticity when no voltage is applied, and 86 is a white point. The chromaticity of the peripheral portion where no voltage is applied corresponds to 85 in FIG. In this case, the chromaticity at room temperature (25 ° C.) is shown. Normally, when the on-voltage is applied, the displayed character color is displayed, and when the off-voltage is applied, the background color is displayed.

When the conventional liquid crystal device is left at a low temperature (0 ° C.), the chromaticity is as shown in FIG. 9, 96 is the chromaticity when an on-voltage is applied, and 97 is an off-voltage. In this case, the chromaticity is 98, and 98 is the chromaticity when no voltage is applied. In the conventional liquid crystal device, the chromaticity when the off voltage is applied and the chromaticity of the outer peripheral portion to which the voltage is not applied are 25
While it is almost the same at 0 ° C, it is greatly different at 0 ° C. At 0 ° C, the color of the outer peripheral portion is red.

Therefore, an object of the present invention is to solve the above problems of the prior art by reducing the change in color of the outer peripheral portion at a low temperature and bringing it closer to the color of the display portion to which the off voltage is applied. This means improving the display quality.

[0012]

In order to solve the above-mentioned problems, according to the present invention, the dispersion density of the spherical powder in the display section is increased and the diameter of the glass fiber in the sealing section is made smaller than that of the display section. The thickness of the liquid crystal layer is set to be thinner than the display portion by 0.1 μm or more in the outer peripheral portion.

[0013]

In the liquid crystal device constructed as described above,
Since the refractive index of the liquid crystal is higher at room temperature than at room temperature, the color of the part where no voltage is applied changes to red at low temperature.
By reducing the thickness of the liquid crystal layer, the birefringence (the product of the thickness of the liquid crystal layer and the refractive index anisotropy) was reduced so that red color did not appear even at low temperatures.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, 11a and 11b are substrates made of glass, plastic, or the like, and have electrode layers 12a and 1b on their surfaces.
2b, alignment film layers 13a and 13b are provided. The pair of substrates are installed so that the alignment film surfaces face each other. 1
4a and 14b are sealing agents for enclosing the liquid crystal,
Glass fiber pieces 15a, 15b in the sealing agent
And a liquid crystal layer 17a, 17b, 1 is attached onto the substrate by screen printing or a displacer.
7c is a spherical powder made of glass or plastic sandwiched between the substrates to keep the thickness of the liquid crystal layer uniform, 18
Reference numerals a and 18b are polarizing plates. Reference numeral 19 is a reflector or a light source.

A method for making the outer peripheral portion of the liquid crystal layer thinner than the display portion will be described. In Figure 2,
The method of spraying spherical powder is shown. In the mask 22, the spherical powder penetrates the display part and does not penetrate the non-display part. When the spherical powder is sprayed by the mask 22, the spherical powder is densely sprayed on the display portion. A small amount of spherical powder is sprayed from below the mask to the non-display portion, that is, the portion hidden by the mask, by wraparound.

The display section is formed by spraying a large number of spherical powders.
Although the liquid crystal layer is uniform, the non-display portion has almost no spherical powder, so the liquid crystal layer cannot be kept uniform and becomes thinner than the display portion. In addition, the diameter of the glass fiber piece in the sealing agent,
When the size is smaller than the spherical powder dispersed in the display portion between the substrates, the sealing portion is likely to be crushed when the pair of substrates are pressure bonded, and the thickness of the liquid crystal layer can be reduced in the outer peripheral portion.

Next, the color measurement results when the thickness of the liquid crystal layer is made smaller by 0.1 μm in the peripheral portion than in the display portion will be shown. FIG. 3 is a diagram showing display colors in the display device of the present invention. In FIG. 3, the color is represented by chromaticity (x, y), 31 indicates the direction of chromaticity x, and 32 indicates the direction of chromaticity y. Here, in the conventional liquid crystal device, 1/64 duty, 1 / 9bia
s and the driving voltage were set so that the contrast ratio became maximum in the normal direction of the liquid crystal device.

33 is the chromaticity when an ON voltage is applied,
Reference numeral 34 is a chromaticity when an off voltage is applied, 35 is a chromaticity when no voltage is applied, and 36 is a white point. The chromaticity of the peripheral portion where no voltage is applied corresponds to 35 in FIG. In this case, the chromaticity at room temperature (25 ° C.) is shown. Normally, when the on-voltage is applied, the displayed character color is displayed, and when the off-voltage is applied, the background color is displayed.

As shown in FIG. 3, the color when the OFF voltage 34 is applied and the color when the voltage 35 is not applied are almost the same and are colors close to the white point of 36. Further, when 33 ON voltage is applied, it is blue. When the liquid crystal device of the present invention is left at a low temperature (0 ° C.), the chromaticity is as shown in FIG. 4, and 44 is the chromaticity when an on-voltage is applied,
Reference numeral 45 represents chromaticity when an off voltage is applied, and 46 represents chromaticity when no voltage is applied.

In the conventional liquid crystal device, the color (98 in FIG. 9) when no voltage is applied at 0 ° C. is (x, y) =
Although (0.3250, 0.3513), in the liquid crystal device of the present invention, the color (46 in FIG. 4) when no voltage is applied at 0 ° C. is (x, y) = (0.3194,
0.3249).

In the conventional liquid crystal device, the color when no voltage is applied is 85 in FIG. 8 at 25 ° C. and 9 in FIG. 9 at 0 ° C.
It becomes 8, and the color close to the white point changes to red. The color when the off-voltage is applied is 84 in FIG. 8 at 25 ° C. and 97 in FIG. 9 at 0 ° C., both of which are close to the white point. If more on-voltage is applied,
Both 25 ° C and 0 ° C are blue.

In the liquid crystal device of the present invention, the color when no voltage is applied is 35 in FIG. 3 at 25 ° C. and 46 in FIG. 4 at 0 ° C.
Both are colors close to the white point. Further, the color when the off-voltage is applied is 34 in FIG. 3 at 25 ° C. and 45 in FIG. 4 at 0 ° C., both of which are from white to slightly blue. If more ON voltage is applied, 25
Both ℃ and 0 ℃ are blue.

As described above, in the conventional liquid crystal device, the peripheral portion to which no voltage is applied is red at low temperature, but in the liquid crystal device of the present invention, the color of the peripheral portion is the same at room temperature and low temperature. As described above, by making the thickness of the liquid crystal layer in the outer peripheral portion of the liquid crystal device thinner by 0.1 μm than the thickness of the liquid crystal layer in the display portion, the chromaticity when the off voltage is applied and the voltage is not applied. The chromaticity of the outer peripheral portion is almost the same at 25 ° C. and 0 ° C. The color of the outer peripheral portion is not red at 0 ° C.

The effect was obtained when the difference between the thickness of the outer peripheral portion and the thickness of the display portion was 0.1 μm or more. In this embodiment, a pair of polarizing plates is provided outside the pair of substrates, but a polymer plate having a refractive index anisotropy between the substrates and the polarizing plate, or a liquid crystal panel with a liquid crystal panel is provided. Also in the device, there is an effect that the color of the outer peripheral portion of the liquid crystal device and the color of the display portion when the off voltage is applied are the same.

[0025]

As described above, according to the present invention, a liquid crystal layer is sandwiched between a pair of substrates each having a transparent electrode and an alignment film provided on the substrates, the outer peripheral portion of the substrates is bonded with a sealing agent, and a spherical shape is provided between the substrates. In a liquid crystal device in which a powder is sandwiched, a glass fiber piece is contained in a sealing agent, and a pair of polarizing plates is installed outside the upper and lower substrates, the thickness of the liquid crystal layer is 0 at the outer peripheral portion than at the display portion. Since the structure is made thinner than 1 μm, there is an effect that the change in color of the outer peripheral portion at low temperature is reduced and the color of the display portion is approximated.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a cross-sectional view of a liquid crystal device of the present invention.

FIG. 2 is an explanatory view showing a method for spraying spherical powder.

FIG. 3 is a diagram showing chromaticity at 25 ° C. of the liquid crystal device of the present invention.

FIG. 4 is a diagram showing chromaticity at 0 ° C. of the liquid crystal device of the present invention.

FIG. 5 is an explanatory diagram showing a cross-sectional view of a liquid crystal device according to a conventional technique.

FIG. 6 is an explanatory diagram showing an optical axis direction of a liquid crystal device.

FIG. 7 is an explanatory diagram showing a display portion and an outer peripheral portion of the liquid crystal device.

FIG. 8 is a diagram showing chromaticity at 25 ° C. of a liquid crystal device according to a conventional technique.

FIG. 9 is a diagram showing chromaticity at 0 ° C. of a liquid crystal device according to a conventional technique.

[Explanation of symbols]

 11a, 11b Substrate 12a, 12b Electrode layer 13a, 13b Alignment film layer 14a, 14b Sealing agent 15a, 15b Glass fiber piece 16 Liquid crystal layer 17a, 17b, 17c Spherical powder 18a, 18b Polarizing plate 19 Reflector or light source

Claims (4)

[Claims] 1. A liquid crystal layer is sandwiched between a pair of substrates each having a transparent electrode on the substrate and an alignment film on the electrodes, and the outer peripheral portion of the substrate is adhered with a sealing agent to form a spherical powder between the substrates. In a liquid crystal device in which a glass fiber piece is contained in the sealing agent and a pair of polarizing plates is installed outside the upper and lower substrates, the thickness of the liquid crystal layer is thinner in the outer peripheral portion than in the display portion. A liquid crystal device characterized by the above. 2. The thickness of the liquid crystal layer at the outer peripheral portion of the liquid crystal device is
The liquid crystal device according to claim 1, wherein the thickness of the liquid crystal layer in the display portion is 0.1 μm or more. 3. The liquid crystal device according to claim 1, wherein the spherical powder between the substrates is dispersed more in the display portion than in the outer peripheral portion of the liquid crystal device. 4. The liquid crystal device according to claim 1, wherein the glass fiber piece in the sealing agent has a diameter smaller than that of the spherical powder dispersed in the display portion between the substrates.