JPH02212812A - Liquid crystal display element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a liquid crystal display element for monochrome or color display using a two-layer liquid crystal cell.

(Prior Art) Conventionally, this type of liquid crystal display element has mainly been one using a TN type (twisted nematic type) liquid crystal cell. It consists of a liquid crystal cell with a liquid crystal layer having a spiral structure, and a pair of upper and lower polarizers arranged to sandwich this liquid crystal cell.This TN type liquid crystal display element is the mainstream of liquid crystal display elements. However, as dot matrix type liquid crystal display elements have become larger in recent years, the number of time divisions has increased, making it difficult to cope with the time division characteristics of conventional TN type liquid crystal display elements. In time-division driving with a ratio of 1/64 or more, display characteristics such as contrast and viewing angle deteriorate.

Therefore, recently, instead of such a TN type,
A liquid crystal display element using a mode called SBE or STN has been proposed and has already been put into practical use. This has a structure that is arranged between two substrates with transparent electrodes, oriented substantially horizontally to the substrates, and twisted at a twist angle of 120° or more and 360' or less, for example, 180° in the thickness direction, and has a positive dielectric difference. It consists of a liquid crystal cell provided with a liquid crystal layer exhibiting orientation, and a pair of upper and lower polarizers disposed to sandwich the liquid crystal cell. In the display system of such a mode called SBE or STN, since coloring due to birefringence of liquid crystal and its change due to voltage are used, display is performed on a colored background. Therefore, by stacking compensation liquid crystal cells each having a liquid crystal layer twisted in the opposite direction and having a twist angle almost equal to that of the display liquid crystal cell, the elliptically polarized wavelength component in the non-selected portion of one display liquid crystal cell is converted into linearly polarized light. A method called a two-layer black-and-white mode was proposed in which the color was changed back to achromatic. This method also has a contrast that is 2 to 3 times higher than the SBE mode or STN mode, and can be used in combination with a color filter to produce color images. In addition, recently, liquid crystal display elements have become thinner, lighter, and easier to process.

From the viewpoint of cost reduction, etc., the use of flexible film substrates such as polyester or polyether sulfone having a thickness of about 1001 is attracting attention as liquid crystal cell substrates.

Figure 2 shows an example of a configuration in which a color filter is formed on one of the display liquid crystal cells in a conventional two-layer monochrome mode to enable color display. The layer 23 consists of two glass substrates 21A, 2
1B with a sealing material 27. Also,
A display transparent electrode 22^ is formed on the surface of one glass substrate 21A of the display liquid crystal cell 20' that is in contact with the liquid crystal, and a color filter 2 is formed on the upper layer corresponding to the electrode pattern.
5-1.25-2.25 to 3... are each R (red)
, G (green), and B (blue) in the order of stripes or staggered arrangement, or in a configuration that optimizes color display, and an alignment film 24 . A is formed. Similarly, on the surface of the opposing glass substrate 21B, display transparent electrodes 22B are formed in a matrix pattern with respect to 22A, and on top of these transparent electrodes 22B are formed an alignment pattern 24B, forming a display liquid crystal cell 20'. Note that 26 is a spherical spacer uniformly distributed throughout the cell in order to maintain a uniform cell gap. A compensating liquid crystal cell 10' is integrated with the display liquid crystal cell 20' by a bonding agent 17 on the upper surface of the display liquid crystal cell 20', that is, the upper surface of the glass substrate 21B. However, it is not always necessary to use a bonding agent.The compensating liquid crystal cell 10' is formed by sealing the liquid crystal layer 13 between the glass substrates 11A and 11B, which are arranged parallel to each other and facing each other, with a sealing material 15. Alignment films 12A and 12B are formed on mutually opposing surfaces of the substrates 11A and 11B. For displaying these.

The laminate of compensation liquid crystal cells 20' and 10' has a polarizing plate 16
It is held by ゜28.

Image display is performed by driving the electrodes of the 1-display liquid crystal cell 20' by applying a voltage, and transmitting the image from the polarizing plate 28 side to the polarizing plate 16 side using color filters 25-1.25-2.25-3...
Various color displays are performed using light whose transmission wavelength is more controlled.Here, the relationship between the display liquid crystal cell 20', the compensation liquid crystal cell 10', and the polarization axes of the upper and lower polarizing plates 16 and 28 is as follows. 1 The relationship between the twist angles of the display liquid crystal and the compensation liquid crystal, Δn-d, etc., are determined by the color filter 25.
-1.25-2.25-3... in a configuration that best reproduces the colors, that is, the display when the color filters 25-1゜25-2.25-3... are not present. is formed so that it has a hue closest to white or black. Such condition settings include 1, for example, JP-A-63-1.5.
Publication No. 1924, Specification of Japanese Patent Application No. 62-234402,
62-2344039 specification, 62-307109
or the specification of No. 63-284164, etc. can be applied. Among these conditions, control of the cell gap is particularly important for manufacturing purposes in order to make the display uniform, and the gap accuracy of ±O, OS or less is required for the display and compensation liquid crystal cells over the entire display surface. Required to cross.

[Problem to be solved by the invention]

However, in the conventional two-layer black-and-white mode color display liquid crystal display element formed with the above configuration, glass substrates are used for both the display and compensation liquid crystal cells, so four glass substrates are required. is required, which increases the thickness of the entire device, and when the device becomes large, the weight increases significantly. This not only makes it difficult to create panels that are thin and lightweight in appearance, but also makes it extremely difficult to control the gap between each cell as the size increases. It had many drawbacks, such as demanding conditions and being expensive.

On the other hand, from this point of view, liquid crystal display elements using the aforementioned flexible film substrates have been developed, but flexible film substrates are inferior to glass substrates in terms of heat resistance, dimensional stability, etc. This made it difficult to create high-definition, high-quality color filters.

Therefore, the present invention is designed to be thinner and lighter as a whole than a two-layer color liquid crystal display element with a conventional configuration in which a total of four glass substrates are used as substrates for one display and compensation liquid crystal cell. It is an object of the present invention to provide a two-layer liquid crystal display element having a novel structure that can maintain a uniform cell gap even when the device is enlarged and can display good color.

[Means to solve the problem]

The present invention comprises: a first glass substrate having a display transparent electrode on one surface and subjected to an orientation treatment to form a screen; a second glass substrate having a display transparent electrode on one surface and subjected to an orientation treatment; Using a flexible film substrate that has been oriented on one side, a first glass substrate and a second glass substrate are placed apart so that the display transparent electrodes face each other, and these two substrates are used to The long axis of the liquid crystal molecules is oriented approximately horizontally, and the thickness direction is 12
A liquid crystal layer having a twisted structure of 0° or more and 360° or less and exhibiting positive dielectric anisotropy is sandwiched between the first glass substrate and the flexible film substrate. A two-layer liquid crystal cell sandwiching a liquid crystal layer whose axes are oriented substantially horizontally and whose thickness direction is twisted in the opposite direction to the liquid crystal layer by 120 degrees or more and 360 degrees or less and exhibits positive dielectric anisotropy. The above-mentioned problem is solved by providing a liquid crystal display element characterized by comprising: and a pair of polarizers disposed above and below the liquid crystal cell.

[For production]

In the structure of the two-layer liquid crystal display element, one of the two glass substrates forming the display liquid crystal cell is made common to the compensation liquid crystal cell, and the other substrate of the compensation liquid crystal cell can be used as the same substrate. By using a flexible film substrate, the device can be made thinner and lighter, and even when the device becomes larger, the cell gap can be easily controlled. Additionally, polishing of the glass substrate surface on the compensation liquid crystal cell side is no longer necessary.

The cost increase due to polishing can be reduced, and a two-layer liquid crystal display element that is easy to manufacture and inexpensive can be realized. 1 more
By providing a color filter on either one of the glass substrates of the display liquid crystal cell, a two-layer color liquid crystal display element with good single display performance can be provided.

〔Example〕

The present invention will be explained in more detail below with reference to Examples.

FIG. 1 is a sectional view showing the structure of a liquid crystal display element according to an embodiment of the present invention. The features of this embodiment are 5 display liquid crystal cells 2
One of the glass substrates 21B of the compensating liquid crystal cell 10 is made common to the other glass substrate 11B of the compensating liquid crystal cell 10. That is, the substrate in contact with the polarizing plate 16 is formed of a flexible film substrate, and the overall structure of a two-layer liquid crystal display element, which conventionally used four glass substrates, is replaced by two glass substrates and a film. It has a three-layer structure with one board, and is thin and
The other configurations and forms of the 0 display liquid crystal cell 20 and the compensation liquid crystal cell 10, which have realized a lightweight structure, are the same as those of the liquid crystal display element shown in FIG. 2, and the same reference numerals are used.

In the configuration of the above embodiment, by using a flexible film substrate as one substrate 11 of the compensation liquid crystal cell 10,
As described in Japanese Patent Application No. 63-284164, 50 spherical particles having a uniform particle size with a standard deviation of 0.3 or less are uniformly distributed throughout the cell as the gap material particle size. /■1~300 pieces l■2. Preferably 100 pieces/
By dispersing at a dispersion density within the range of ζ 200 pieces/kaku1 and using a low-temperature thermosetting sealing material, the cell gap can be made uniform, and the surface tension of the injected liquid crystal can also be applied to the flexible film. The result is that the substrate 11 is pulled along the undulations of the surface of the common glass substrate 21B on the compensating liquid crystal layer 13 side.

A more precise cell gap is achieved. As a result, at least the surface of the common glass substrate 21B on the compensating liquid crystal layer 13 side does not require surface polishing, and a uniform cell gap can be maintained over a large area. As the flexible film substrate 11, an optically substantially isotropic substrate such as polyether sulfone, polycarbonate, or polyimide can be used.

Furthermore, it is also possible to use a substrate 9 having an optical axis as the flexible film substrate 11, such as a -axis polyester substrate.

In this case, compared to an optically isotropic film substrate, -
The characteristics of the refractive index in the thickness direction of the axial film substrate provide advantages such as a wider display viewing angle range compared to a monoisotropic film substrate.

In addition, a color filter 25- that enables color display is provided.
1.25-2.25-3... are display liquid crystal cells 20
It may be formed on either of the surfaces of the first and second glass substrates 21A and 21B that are in contact with the liquid crystal layer 23.

As an example of the configuration shown in FIG. 1, the glass substrate 2 of the display cell 20 is
An example formed on 1A is shown.

Furthermore, it goes without saying that the R, G, and B color filters described above are not limited to the configuration shown in FIG. 1, but may be formed under one display transparent electrode 22A. Generally, dyeing methods, printing methods, photolithography methods using photosensitive colored inks, etc. can be applied to the formation method of the above color filter, and the method that suits the purpose can be selected depending on the dot size, required accuracy, etc. .

Next, an example of a method for manufacturing a two-layer color liquid crystal display element having the structure shown in FIG. 1 will be described with reference to FIG. 3.

First, in the first step ((■) in FIG. 3), the color filters 25-1, 25-2,
On the glass substrate 2IA on the side where 25-3... is formed,
A transparent conductive film (generally IT
After forming an ITO film (O film), this ITO film is patterned into a predetermined shape using a photolithography method to form a transparent electrode 22A for one display. On the other hand, similarly, the glass substrate 2 on the opposite side
The ITO film on 1B is patterned in a similar manner to form a transparent display electrode 22B. Here, it is desirable that the surfaces of the glass substrates 21A and 21B be polished to a predetermined precision before forming the ITO film.

When forming an electrode pattern on the surface of the glass substrate 21B, the back side is covered with a protective film 30, and then a second step (
In (■) of FIG. 3, on the glass substrate 21A side, R, G, B color filters 25-1.25-2.25-3... On the other hand, on the glass substrate 21B side, after printing orientation 1flJ24B on the display transparent electrode 22B by a printing method,
In the 9th example, which is baked at a predetermined baking temperature or lower,
HL-1110 (Hitachi Kaisha, Ltd.) was used as an alignment agent, and the buri-bake temperature was 60°C.

In the third step ((■) in FIG. 3), the glass substrate 21A
Color filters 25-1 and 25-2 provided above
．． 25-3... On the other hand, the alignment agent HL-1110 (Hitachi Chemical II) is applied by printing, and a post bake is performed at 150° C. for 60 min.

Regarding the common glass substrate 21B, an alignment film 12A is printed and formed on the non-polished surface from which the protective film 30 has been removed. Here, an alignment film 2 is placed on the display transparent electrode 22B of the substrate 21B.
The surface on which 4B is formed is held by a holder 40 that keeps the surface in a non-contact state. after that.

Under the same conditions as above, the alignment films 12A and 24B of the screen of the common glass substrate 21B are simultaneously post-baked - again.

An alignment film 12B is similarly applied to the surface of the other flexible film substrate 11 for forming the compensation liquid crystal cell 10.
and post-bake at 100-120°C and 60m1n.

Thereafter, the alignment film on each substrate is rubbed at a predetermined angle using a general method. Here, in the rubbing process of the alignment films 12A and 24B of the screen of the common glass substrate 21B, when rubbing one surface, it is necessary to use the holder 40 to keep the other surface in a non-contact state.

Next, a two-layer cell having the configuration shown in FIG. 1 is formed using each of the above substrates ((rV) in FIG. 3).

At this time, the gap materials 14 and 26 are uniformly distributed on the screen of the common glass substrate 21B at a predetermined distribution density.

On the other hand, the glass substrate 21A and the flexible film substrate 11
A low-temperature thermosetting sealing material is printed around it in a shape that leaves an injection hole for injecting the liquid crystal, and the glass substrate 21A and the common glass substrate 21B are first bonded (bonding ■).
Next, the flexible film substrate 11 is bonded (bonding ■), and a load is applied from above the flexible film substrate 11 to obtain a uniform cell gap and seal thickness, and the sealing material is cured. The sealing material curing conditions used were 80'C-100C and 60-60-8O.

Liquid crystals having different twist directions were injected under vacuum into the display and compensation liquid crystal cells of the two-layer cell formed as described above to form a two-layer color liquid crystal display element. here,
A liquid crystal display element was fabricated using optically isotropic polyether sulfone and optically anisotropic uniaxially stretched polyester as the film substrate of the two-layer cell, and polarizing plates 16 and 28 were formed on both sides, respectively. After bonding them together at a predetermined angle, the display performance of each film was compared, and although good color display was obtained in all cases, it was found that the -axis stretched film was better in terms of viewing angle characteristics.

〔Effect of the invention〕

As explained in detail above, in the present invention, a display liquid crystal cell is formed from two opposing glass substrates, and further, one of the glass substrates is used as a common glass substrate for forming a two-layer cell structure, By forming a compensating liquid crystal cell using this common glass substrate and flexible film substrate, it became possible to realize a two-layer liquid crystal display element using three substrates as a whole.

Therefore, with the above configuration, compared to a conventional two-layer liquid crystal display device using four glass substrates, it is possible to achieve a thinner and lighter design, reduce the cost increase due to polishing the glass surface, and also make the device larger. Cell gap control can be achieved with high precision even when

Further, according to the present invention, by providing a color filter corresponding to the display pixel on one side of one of the two glass substrates of the display liquid crystal cell, the above-mentioned advantages are provided, and a good color display can be achieved. This makes it possible to provide a two-layer color liquid crystal display element.

Furthermore, according to the present invention, by using a film having an optical axis on the flexible film substrate side of the compensation liquid crystal cell, it is possible to widen the viewing angle range for one display, further improving display performance. becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of the structure of a two-layer color liquid crystal display element according to the present invention, FIG. 2 is a sectional view showing an example of the structure of a conventional two-layer color liquid crystal display element, and FIG. FIG. 3 is a process diagram showing a method for manufacturing the liquid crystal display element shown in the figure. 10... Compensation liquid crystal cell 11... Flexible film substrate 12A, 12B, 24A, 24B... Alignment film 13.2
3...Liquid crystal layer 1.4.26...Gap material 16.28...Polarizing plate 20...Display liquid crystal cell 21A, 21B...Glass substrate 22A, 22B...Transparent electrode 25- 1.25-2.25-3～ Color filter patent applicant Rico Co., Ltd. −

Claims (1)

[Claims] (1) A first glass substrate that has a display transparent electrode on one surface and has been subjected to an orientation treatment to form a screen; a second glass substrate that has a display transparent electrode on one surface and has an orientation treatment; A first glass substrate and a second glass substrate are placed apart so that the display transparent electrodes face each other, using a flexible film substrate whose surface is oriented. The long axis of the molecule is oriented approximately horizontally at 120° in the thickness direction.
A liquid crystal layer having a structure twisted by 360° or less and exhibiting positive dielectric anisotropy is sandwiched between the first glass substrate and the flexible film substrate, and the long molecular axis of the liquid crystal is aligned with respect to both substrates. 1 in the opposite direction to the liquid crystal layer in the thickness direction, which is oriented approximately horizontally.
A two-layer liquid crystal cell sandwiching a liquid crystal layer having a twisted structure of 20° or more and 360° or less and exhibiting positive dielectric anisotropy, and a pair of polarizers disposed above and below the liquid crystal cell. A liquid crystal display element characterized by: