JPH05249444A - Liquid crystal display - Google Patents

Abstract

(57) [Abstract] [Purpose] Corresponding to the central portions of the transparent substrates 11 and 12 even if there is a temperature difference between the central portions of the transparent substrates 11 and 12 and the peripheral portions of the surface due to uneven brightness of the backlight light. It is possible to reduce the difference in operating voltage value between the liquid crystal layer 17 in a part and the liquid crystal layer 17 in a part corresponding to the peripheral portions of the transparent substrates 11 and 12.
It is an object of the present invention to provide a liquid crystal display device capable of displaying a good image without uneven contrast. The liquid crystal layer 17 in the portions corresponding to the central portions of the transparent substrates 11 and 12 is made thicker than the liquid crystal layer 17 in the portions corresponding to the peripheral portions of the transparent substrates 11 and 12.

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 used as a display portion of a liquid crystal projector, a liquid crystal television or the like.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, a liquid crystal display device of this type has a first transparent substrate 1 made of glass, a film or the like, and a first transparent substrate 1 provided so as to face the first transparent substrate 1. Two transparent substrates 2 are provided, and transparent electrodes 3 and 4 are formed on the surfaces of the first and second transparent substrates 1 and 2 facing each other.

One of the transparent electrodes 3 and 4 is for display and the other is for scanning, and they are respectively connected to a drive circuit (not shown). The transparent electrodes 3 and 4 are covered with alignment films 5 and 6, and a liquid crystal layer 7 is formed between the alignment films 5 and 6.

The liquid crystal layer 7 is formed by encapsulating liquid crystal in a space formed between the first transparent substrate 1 and the second transparent substrate 2 by a sealing material 8, and is formed from the drive circuit to the transparent electrode. It operates according to the voltage applied to 3,4.

[0005]

By the way, in such a liquid crystal display device, when the first transparent substrate 1 or the second transparent substrate 2 is irradiated with backlight light from a light source (not shown), the backlight light emits first light. Of the transparent substrate 1 or the second transparent substrate 2 of the first transparent substrate 1 is not necessarily illuminated uniformly, and the backlight light emitted to the central portion of the surface of the first transparent substrate 1 or the second transparent substrate 2 is the first transparent substrate. The brightness becomes higher than that of the backlight light emitted to the peripheral portion of the surface of the first or second transparent substrate 2. Therefore, the temperature of the central portion of the surface of the first transparent substrate 1 or the second transparent substrate 2 is higher by about 3 to 8 ° C. than that of the peripheral portion of the surface. And thus the first
When the central part of the surface of the transparent substrate 1 or the second transparent substrate 2 is higher than the peripheral part of the surface by about 3 to 8 ° C., the operating voltage value (responsiveness) of the liquid crystal layer 7 changes depending on the temperature. 7 is Δnd = 828 nm, and the surface temperature of the central portion and the peripheral portion of the first transparent substrate 1 or the second transparent substrate 2 irradiated with the backlight light is 40 ° C. and 3 ° C., respectively.
When the temperature is 5 ° C., the liquid crystal layer 7 in the peripheral portions of the transparent substrates 1 and 2 has an operating voltage value of 20.8 V, whereas the liquid crystal in the central portion of the transparent substrates 1 and 2 is liquid crystal layer 7. Layer 7
Has an operating voltage value of 20.3V. When the operating voltage value of the liquid crystal layer 7 is low in the central portions of the transparent substrates 1 and 2 and high in the peripheral portions in this way, a bright image appears in the central portions of the transparent substrates 1 and 2 and a dark image appears in the peripheral portions, resulting in a contrast. There was a problem of unevenness in the skin.

The present invention has been made in view of the above problems, and an object thereof is to keep the surface temperature of a transparent substrate relatively even if a temperature difference occurs due to uneven brightness of backlight light depending on the region of the transparent substrate. (EN) Provided is a liquid crystal display device capable of reducing a difference in operating voltage value between a liquid crystal layer of a portion having a high temperature and a liquid crystal layer of other portions and capable of displaying a good image without unevenness in contrast. It is in.

[0007]

In order to solve the above-mentioned problems, the present invention provides a first transparent substrate, a second transparent substrate provided facing the first transparent substrate, and a first transparent substrate. And a liquid crystal display device having a transparent electrode formed on the inner surface of each of the second transparent substrates and a liquid crystal layer formed between the transparent electrodes, a portion of the transparent substrate having a relatively high temperature. The liquid crystal layer of is thicker than the liquid crystal layer of the portion corresponding to other portions.

[0008]

In the present invention, the liquid crystal layer of the portion where the surface temperature is relatively high is made thicker than the liquid crystal layer of the other portion, so that the retardation of the liquid crystal layer of the portion where the surface temperature is high is the liquid crystal layer of the other portion. Is larger than that of the liquid crystal layer, the operating voltage value of the liquid crystal layer in the portion where the surface temperature becomes relatively high can be made closer to the operating voltage value of the liquid crystal layer in the other portions. Therefore, for example, even if there is a temperature difference between the central portion of the surface of the transparent substrate and the peripheral portion of the surface due to uneven brightness of the backlight, the liquid crystal layer in the portion corresponding to the central portion of the transparent substrate and the peripheral portion of the transparent substrate are It is possible to reduce the difference in operating voltage value between the liquid crystal layer and the corresponding portion.

[0009]

FIG. 1 is a diagram showing an embodiment of a liquid crystal display device according to the present invention, which is a first transparent substrate 1
1 and a second transparent substrate 12 provided so as to face the first transparent substrate 11.

The transparent substrates 11 and 12 are made of, for example, glass, and transparent electrodes 13 and 14 are formed on the surfaces of the transparent substrates 11 and 12 facing each other. One of these transparent electrodes 13 and 14 is for display and the other is for scanning, and they are respectively connected to a drive circuit (not shown).

The transparent electrodes 13 and 14 are the alignment film 1
5, 16 and are covered with these alignment films 15, 1.
A liquid crystal layer 17 is formed between the layers 6. This liquid crystal layer 1
7 is a transparent substrate 11 and a transparent substrate 12 by means of a sealing material 18.
The liquid crystal is sealed in a space formed between the transparent electrode and the transparent electrode, and the liquid crystal device is operated by the voltage applied to the transparent electrodes 13 and 14. Further, in the liquid crystal layer 17, the portion corresponding to the central portion of the transparent substrates 11 and 12 is the transparent substrate 1.
It is thicker than the portions corresponding to the peripheral portions of 1 and 12.

In the liquid crystal display device constructed as above,
The liquid crystal layer 1 in the portion corresponding to the central portion of the transparent substrates 11 and 12
Since 7 is thicker than the liquid crystal layer 17 in the portions corresponding to the peripheral portions of the transparent substrates 11 and 12, the transparent substrates 11 and 12 are
The retardation of the liquid crystal layer 17 in the portion corresponding to the central portion of the transparent substrate 1 is larger than the retardation of the liquid crystal layer 17 in the portions corresponding to the peripheral portions of the transparent substrates 11 and 12.
The operating voltage value of the liquid crystal layer 17 in the portions corresponding to the central portions of 1 and 12 can be made close to the operating voltage value of the liquid crystal layer 17 in the portions corresponding to the peripheral portions of the transparent substrates 11 and 12.

Therefore, even if a temperature difference is caused between the central portions of the surfaces of the transparent substrates 11 and 12 and the peripheral portions of the surfaces due to the uneven brightness of the backlight light, the liquid crystal layer of the portion corresponding to the central portions of the transparent substrates 11 and 12 is formed. It is possible to reduce the difference in operating voltage value between the liquid crystal layer 17 and the liquid crystal layer 17 in the portions corresponding to the peripheral portions of the transparent substrates 11 and 12, whereby the liquid crystal layer 17 in the portions corresponding to the central portions of the transparent substrates 11 and 12 can be reduced. Since the liquid crystal layer 17 in the portions corresponding to the peripheral portions of the transparent substrates 11 and 12 operates almost at the same time, it is possible to display a good image without uneven contrast.

FIG. 2 is a diagram showing the relationship between the operating voltage value and the temperature of the liquid crystal, and the solid line A shows the retardation Δnd =
The liquid crystal layer in the case of 0.23 × 3.6 μm = 828 nm is shown, and the solid line B shows the retardation Δnd = 0.23 × 3.
6 shows a liquid crystal layer when 654 μm = 840.5 nm. As shown in the figure, the liquid crystal layer shown by the solid line A has an operating voltage value of 20.8 V when the temperature is 35 ° C., and the liquid crystal layer shown by the solid line B has an operating voltage value of 20. Since the voltage is 8 V, the liquid crystal layer 17 in the portions corresponding to the central portions of the transparent substrates 11 and 12 is made thicker than the liquid crystal layer 17 in the portions corresponding to the peripheral portions of the transparent substrates 11 and 12 by 0.54 μm. It is possible to make the operating voltage values of the liquid crystal layer 17 in the portions corresponding to the central portions of 11 and 12 and the liquid crystal layers 17 in the portions corresponding to the peripheral portions of the transparent substrates 11 and 12 substantially constant.

As a method of making the liquid crystal layer 17 in the portions corresponding to the central portions of the transparent substrates 11 and 12 thicker than the liquid crystal layer 17 in the portions corresponding to the peripheral portions of the transparent substrates 11 and 12, for example, as shown in FIG. The transparent substrate 11 and 12 is pressed by the press device 21.
A rubber mat 22 is arranged between the transparent substrates 11 and 12 and the pressing device 21 when pressing the liquid crystal layer 17 from both sides with a constant thickness as shown in FIG. If the hole 23 is opened, the transparent substrate 11,
Since the central portion of 12 is not pressed, the transparent substrate 1
The liquid crystal layer 17 in the portions corresponding to the central portions of the transparent substrates 1 and 12 can be made thicker than the liquid crystal layer 17 in the portions corresponding to the peripheral portions of the transparent substrates 11 and 12.

As another method, as shown in FIG.
When the liquid crystal 26 is vacuum-injected into the CD panel 25, the LCD
A method of thickening the liquid crystal layer 17 at a portion corresponding to the central portion of the transparent substrates 11 and 12 by pulling the central portion of the panel surface of the panel 25 (the central portion of the surface of the transparent substrates 11 and 12) from both sides with the suction cup members 24 is also considered. Be done.

Further, the cause of the temperature difference generated in the transparent substrate is not limited to the one caused by the backlight, but may be the driver of the liquid crystal display device, etc. Therefore, the region where the temperature difference is generated is different from the one side of the transparent substrate. The edge side or the like is suitable, and in those cases, the liquid crystal layer on the high temperature side may be thickened.

In the embodiment, the example applied to the simple matrix liquid crystal display device is shown, but it goes without saying that the present invention can also be applied to an active matrix type liquid crystal display device.

[0019]

As described above, according to the present invention, since the liquid crystal layer in the region where the temperature of the transparent substrate becomes relatively high is made thicker than the liquid crystal layer in the other regions, the region where the temperature becomes relatively high becomes relatively high. The operating voltage value of the liquid crystal layer can be made closer to the operating voltage value of the liquid crystal layer in other regions. Therefore, for example, even if there is a temperature difference between the central portion of the surface of the transparent substrate and the peripheral portion of the surface due to uneven brightness of the backlight, the liquid crystal layer in the portion corresponding to the central portion of the transparent substrate and the peripheral portion of the transparent substrate are It is possible to provide a liquid crystal display device capable of reducing a difference in operating voltage value from a liquid crystal layer in a corresponding portion and displaying a good image without unevenness in contrast.

[Brief description of drawings]

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

FIG. 2 is a diagram showing the relationship between operating voltage and temperature of liquid crystal.

FIG. 3 is an explanatory diagram for explaining an example of a method of making a liquid crystal layer in a portion corresponding to a central portion of the transparent substrate thicker than a liquid crystal layer in a portion corresponding to a peripheral portion of the transparent substrate.

FIG. 4 is a view taken along the line AA of FIG.

FIG. 5 is an explanatory diagram for explaining another example of the method of making the liquid crystal layer of the portion corresponding to the central portion of the transparent substrate thicker than the liquid crystal layer of the portion corresponding to the peripheral portion of the transparent substrate.

FIG. 6 is a sectional view of a conventional liquid crystal display device.

[Explanation of symbols]

11 ... 1st transparent substrate, 12 ... 2nd transparent substrate, 13,
14 ... Transparent electrodes, 15, 16 ... Alignment film, 17 ... Liquid crystal layer,
18 ... Sealing material.

Claims (1)

[Claims] 1. A first transparent substrate, a second transparent substrate provided to face the first transparent substrate, and transparent electrodes formed on the inner surfaces of the first and second transparent substrates, respectively. And a liquid crystal layer formed between each of the transparent electrodes, a liquid crystal layer of a portion of the transparent substrate that has a relatively high temperature is formed from a liquid crystal layer of a portion corresponding to other portions. A liquid crystal display device characterized by being made thicker.