JPH07140461A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To make the contrast of a large-screen display in respective directions excellent and to improve visual sensation characteristics by making the arrangement angles of polarizing plates arranged on plural liquid crystal panel different in the rubbing directions of the liquid crystal panels. CONSTITUTION:In this liquid crystal display device arranged with plural liquid crystal panels and executing a single video display, the plural liquid crystal panels has the polarizing plates at different installation angles in the rubbing directions of the liquid crystal panels. For example, TN cells in multi-gap structure are used and arranged while the installation angles of the panels to the rubbing directions of the polarizing plates are made different. Here, TN cells which use liquid crystal ZL14792 produced by Merk Co. and employ the multi- gap structure are used. Then an orientation process is performed so that visual sensation characteristics of liquid crystal panels which are arranged in the upper half are made 180 deg. different from those of the lower half, and the liquid crystal gap thickness is set to DELTAnd/lambda-0.85. Here, DELTAn is the anisotropy of the refractive index of the liquid crystal material, (d) is the liquid crystal thickness, and lambda is the wavelength of light passing through the liquid crystal cells.

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,
More specifically, the present invention can be applied to a liquid crystal display device in which a large number of TN liquid crystal panels are arranged to perform a large screen display. In particular, when performing a large screen display, the contrast in each direction to the large screen is made good and the visual characteristics are improved. And a liquid crystal display device capable of improving

In recent years, in a liquid crystal panel, particularly in a TN liquid crystal panel which is widely used nowadays, the improvement of the visual characteristics has become a big problem, and the visual characteristics deteriorate as the display area increases. However, in a display device system in which a large number of liquid crystal panels are arranged to display a super-large screen, it is essential to improve the visual characteristics, and it is strongly desired to improve the characteristics.

Therefore, the present invention solves the problem that the visual characteristics are deteriorated by changing the arrangement of the polarizing plates for each liquid crystal panel with respect to the rubbing direction, and the display of the super large screen display system is solved. It significantly improves the quality.

[0004]

2. Description of the Related Art Conventionally, in a display device system for displaying a large screen, the same rubbing process is performed as shown in FIG.
A large number of, for example, left twist type liquid crystal panels in which polarizing plates are arranged in the rubbing direction are arranged.

[0005]

However, in the conventional liquid crystal display device as described above, as shown in FIG. 19 (a), it is large in the U (up) direction, C (front) direction, and L (down) direction. Looking at the screen, as shown in FIG. 20, the contrast is just right and looks good in the C (front) direction.
In the (down) direction, the contrast becomes too small and looks whitish, and in the U (up) direction, the contrast becomes too large and looks black, and as a result, the visual characteristics deteriorate in the viewing direction. It was This problem tends to become more prominent as the screen becomes larger.

Therefore, in the present invention, when a large screen display is performed,
An object of the present invention is to provide a liquid crystal display device that can improve the visual characteristics by improving the contrast in each direction on a large screen.

[0007]

To achieve the above object, a liquid crystal display device according to the present invention is a liquid crystal display device in which a plurality of liquid crystal panels are arranged to display a single image, and a polarizing plate arranged on the liquid crystal panel. The liquid crystal panel includes a plurality of liquid crystal panels having different installation angles with respect to the rubbing direction (orientation direction) of the liquid crystal panel.

In the present invention, the liquid crystal panel is
The liquid crystal gap thickness is Δnd / λ (Δ
(n: anisotropy of refractive index of liquid crystal material, d: thickness of liquid crystal layer, λ: wavelength of light passing through liquid crystal cell) is a panel (multi-gap) structure in which the thickness of the liquid crystal layer is changed to be constant. In this case, it is possible to make the transmittance difficult to change and improve the brightness.

In the present invention, in the normally white mode (white display occurs when no voltage is applied), the installation angle of the polarizing plate is changed with the angle formed by the polarizing plate being 90 degrees, and the normally black mode (voltage When a black display is made when the light is not applied), the angle formed by the polarizing plate may be set to 0 degree, and the installation angle of the polarizing plate may be changed. In this case, normally white mode and normally black The visual characteristics can be improved even in the mode.

In the present invention, the liquid crystal panel may be a TN liquid crystal panel having domains having different visual characteristics by 180 degrees. In this case, the TN liquid crystal panel is used.
Even in the liquid crystal panel, it is possible to prevent the brightness inversion from occurring easily, so that it can be favorably applied in the case of full-color display. In the present invention, the liquid crystal panel and the pair of polarizing plates may be configured to have an optical compensation film having a negative anisotropy in the thickness direction, in which case an optical compensation film is provided. The visual characteristics can be further improved as compared with the case where there is no.

[0011]

1 to 4 are diagrams for explaining the principle of the present invention. Conventionally, as shown in FIG. 2 (a), the polarizer was installed in the rubbing direction. Therefore, as shown by the iso-contrast curve in FIG. 2 (b), the visual characteristics in the horizontal direction are good, but in the vertical direction. In particular, it can be seen that the visual characteristics in the upward direction are poor. In contrast,
As shown in FIGS. 1 (a), 3 (a), and 4 (a), when the installation angle of the polarizing plate with respect to the rubbing direction is appropriately changed, FIG. 1 (b), FIG. 3 (b), and FIG. As shown by the arrow in b), it can be seen that the visual characteristics can be greatly changed in any direction depending on the installation angle of the polarizing plate. Therefore,
In the present invention, in a liquid crystal display device in which a plurality of liquid crystal panels are arranged for display, by changing the installation angle with respect to the rubbing direction (alignment direction) of the polarizing plates arranged in each liquid crystal panel, that is, The problem of visual characteristics can be solved by using the same TN panel and only attaching the polarizing plate.

Here, the fact that the present invention can be easily realized will be described from the polarization state of light passing through the TN cell. Here, as the optical system, consider an optical system as shown in FIG.
6 to 9 show the transmitted light intensity at that time when the polarizing plate on the emission side is rotated 360 degrees. The optical system of FIG.
Incident side polarizing plate (absorption axis) → left twist type alignment division TN cell (liquid crystal: manufactured by Merck, trade name ZLI4792, Δn =
0.094)-> emission side polarization plate (absorption axis) in this order, so that the observer can see from the emission side polarization plate of this panel. 6 to 9 show the installation position (absorption axis direction) of the incident side polarizer in the optical system shown in FIG.
FIG. 6 (a) shows the transmitted light intensity with respect to the exit side polarizer angle when the angle is 45 °, 45 °, 67.5 °, 90 °.
7 (a), 8 (a) and 9 (a) shows λ = 420n.
6B, FIG. 7B, and FIG. 8B.
And FIG. 9B shows the case where λ = 550 nm.
(C), FIG. 7 (c), FIG. 8 (c) and FIG. 9 (c) show λ =
This is the case of 610 nm.

Thus, the absorption axis direction of each polarizing plate is set to 2
When it is set to 2.5 degrees, 45 degrees, 67.5 degrees, and 90 degrees,
When the absorption axes of the polarizing plates on the output side are the same (para arrangement), the liquid crystal gap thickness at which the transmitted light intensity becomes the minimum (0) exists,
They are the same for all polarizer arrangements, λ = 420
nm is ˜4.0 μm, λ = 550 nm is 5.0 μm, and λ = 610 nm is 5.8 μm.

From this, it means that under appropriate Δnd / λ, no matter which azimuth angle the linearly polarized light enters, the linearly polarized light can be realized in the direction rotated by 90 degrees by passing through the liquid crystal layer. Therefore, it can be seen that the visual characteristics can be changed regardless of the position of the polarizing plate. That is, it means that the display can be performed in any polarizing plate arrangement (para is provided in the case of normally black and cross condition is provided in the case of normally white), which proves that this mode itself can be realized. Under such an arrangement, the visual characteristics are shown in FIGS.
It can be seen that the visual characteristics can be appropriately controlled in any direction. Therefore, by arranging substantially the same TN panel as the conventional one according to the use and appropriately changing the installation angle of the polarizing plate with respect to the rubbing direction (orientation direction),
It is possible to control the visual characteristics by improving the contrast in all the directions of the left and right and the diagonal direction, and it is possible to realize a liquid crystal display device having excellent visual characteristics as a large display system.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 10 is a diagram showing a cell arrangement of a large-sized display according to Embodiment 1 of the present invention, and FIG. 11 is a diagram showing a relationship between the large-sized display shown in FIG. 10 and an observer. In this embodiment, T having the above-mentioned multi-gap structure is used.
As shown in FIG. 10, an N cell is used.
In the relationship between the display of 1 and the observer, the contrast is improved in all directions of up, down, left and right, and the oblique direction so that the visual characteristics are improved, that is, the installation angle of the panel with respect to the rubbing direction of the polarizing plate is changed. Place it. The liquid crystal panel used here is a product name ZLI manufactured by Merck & Co., Inc.
A liquid crystal of 4792 is used, and a TN cell adopting a multi-gap structure is used. The liquid crystal panels arranged in the upper half and those arranged in the lower half have a visual characteristic of 18
The orientation treatment is performed so that the orientation is different by 0 degree. This is equivalent to using a liquid crystal panel arranged in the upper half rotated 180 degrees. Further, the liquid crystal gap thickness is set to Δnd / λ to 0.85, that is, the condition that the TN gap condition is the smallest is adopted.

It goes without saying that the panel may be either an active drive type or a simple matrix drive type and can be selected according to the application. 10 and 1
The arrangement of the display and the observer shown in 1 is an arrangement that focuses on the absence of luminance inversion in the TN cell,
It is suitable for full-color display. However, in the case of simply performing multi-color display and focusing only on the contrast, the arrangement of the TN cells may be changed in the upper and lower half minutes without changing the arrangement of the polarizing plates.

(Embodiment 2) FIG. 12 is a diagram showing a cell arrangement of a large-sized display having domains according to Embodiment 2 of the present invention. In this embodiment, as the liquid crystal panel of FIG. 12, a liquid crystal domain having a minimum display pixel or a liquid crystal domain having a visual characteristic different by 180 degrees is used in the panel, and the liquid crystal domain is formed in each display unit, and the upper and lower sides of each display unit are formed. The one with directional symmetry is used. 2 here
This is a method of forming seed domains, but when the display unit is relatively large, this can be easily achieved by twice rubbing using a mask as shown in FIGS. 13 (a) and 13 (b), for example. You can

FIG. 13A shows the rubbing treatment of the lower substrate (on the film surface), and FIG. 13B shows the rubbing treatment of the upper substrate (under the film surface, under the mask). There is. In this case, since each display unit has vertical symmetry, it is not necessary to rotate the upper half cell and the lower half cell on the large screen by rotating them by 180 degrees. On the other hand, when the display unit is small, it can be easily realized by using a manufacturing method utilizing photolithography or the like.

(Embodiment 3) FIG. 14 is a view showing an optical system in which an optical compensation film is provided between a TN cell and an outgoing side polarizing plate according to Embodiment 3 of the present invention. In this embodiment, as shown in FIG. 14, an optical compensation film having negative refractive index anisotropy in the thickness direction is provided between the liquid crystal panel and the polarizing plate on the emission side. The optical compensation film used here is
As shown in FIG. 15, it has a refractive index ellipsoidal structure. When a large-sized display was constructed by arranging the cells as in Example 1, as shown in FIGS.
The visual characteristics of the upper left and upper right angles of 45 degrees and the visual characteristics of the 45 degree azimuth are remarkably improved, and a panel having visual characteristics superior to those of the first embodiment can be obtained.

[0020]

According to the present invention, when a large screen display is performed,
There is an effect that it is possible to improve the visual characteristics by improving the contrast in each direction to the large screen.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a diagram illustrating the principle of the present invention.

FIG. 3 is a diagram illustrating the principle of the present invention.

FIG. 4 is a diagram illustrating the principle of the present invention.

FIG. 5 is a diagram showing an optical system applicable to the present invention.

FIG. 6 shows a case where the absorption axis direction of the polarizing plate is set to 2 in the optical system shown in FIG.
It is a figure which shows the transmitted light intensity with respect to the exit side polarizer angle when it is set to 2.5 degrees.

FIG. 7 shows an optical system shown in FIG.
It is a figure which shows the transmitted light intensity with respect to the exit side polarizer angle at the time of degrees.

FIG. 8 is a drawing showing the optical axis shown in FIG.
It is a figure which shows the transmitted light intensity with respect to the exit side polarizer angle at 7.5 degrees.

FIG. 9 is a view showing an optical axis shown in FIG.
It is a figure which shows the transmitted light intensity with respect to the exit side polarizer angle at the time of degrees.

FIG. 10 is a diagram showing a cell arrangement of the large-sized display according to the first embodiment of the present invention.

11 is a diagram showing a relationship between the large display shown in FIG. 10 and an observer.

FIG. 12 is a diagram showing a cell layout of a large-sized display having domains according to a second embodiment of the present invention.

13 is a diagram showing a method for forming the two types of domains shown in FIG.

FIG. 14 is a diagram showing an optical system in which an optical compensation film is provided between a TN cell and an outgoing side polarizing plate according to Example 3 of the present invention.

15 is a diagram showing a refractive index ellipsoidal structure of the optical compensation film shown in FIG.

16 is a diagram showing the effect of improving the visual characteristics in the upper left 45 ° direction when the optical compensation film shown in FIGS. 14 and 15 is used.

FIG. 17 is a diagram showing the effect of improving the visual characteristics in the upper right 45 ° direction when the optical compensation film shown in FIGS. 14 and 15 is used.

FIG. 18 is a diagram showing the effect of improving the visual characteristics in the oblique 45 ° azimuth when the optical compensation film shown in FIGS. 14 and 15 is used.

FIG. 19 is a diagram showing a conventional left twist type display device system for displaying a large screen.

FIG. 20 is a diagram showing a conventional problem.

Claims (5)

[Claims] 1. In a liquid crystal display device in which a plurality of liquid crystal panels are arranged to display a single image, a plurality of liquid crystal panels in which the polarizing plates arranged in the liquid crystal panel have different installation angles with respect to the rubbing direction of the liquid crystal panel are provided. A liquid crystal display device comprising: 2. The liquid crystal panel, wherein the liquid crystal gap thickness is Δnd / λ (Δn: anisotropy of refractive index of liquid crystal material, d: liquid crystal layer thickness, λ: liquid crystal cell) in each of red, green and blue pixels. The liquid crystal display device according to claim 1, wherein the liquid crystal display device has a panel structure in which the thickness of the liquid crystal layer is changed so that the wavelength of light to be emitted is constant. 3. In the normally white mode, the angle of the polarizing plate is set to 90 degrees to change the installation angle of the polarizing plate. In the normally black mode, the angle of the polarizing plate is set to 0 degree. The liquid crystal display device according to claim 1, wherein the installation angle is changed. 4. The liquid crystal display device according to claim 1, wherein the liquid crystal panel is a TN liquid crystal panel having domains whose visual characteristics differ by 180 degrees. 5. The liquid crystal display device according to claim 1, further comprising an optical compensation film having a negative refractive index anisotropy in a thickness direction between the liquid crystal panel and the polarizing plate.