JPH0497319A - 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 [Field of Industrial Application] The present invention relates to a liquid crystal display element using ferroelectric liquid crystal.

[Conventional technology]

2. Description of the Related Art Some liquid crystal display elements that display television images and the like use ferroelectric liquid crystal.

FIG. 4 is a cross-sectional view of a conventional liquid crystal display element using ferroelectric liquid crystal, and A in the figure indicates an image display area of this liquid crystal display element. This liquid crystal display element has a large number of transparent display electrodes 3.4 formed in a portion corresponding to the image display area A, and an alignment-treated insulating film 5.4 on the electrode formation surface.
A pair of transparent substrates 1 . A ferroelectric liquid crystal LC is sealed, and polarizing plates 8 and 9 are arranged on the outer surfaces of both substrates 1.2, respectively.

The liquid crystal display element shown in FIG. 4 is of a simple matrix type, and the display electrodes 3 on one surface of one substrate (lower substrate in the figure) are striped scanning electrodes, and the display electrodes 3 on the other substrate (lower substrate in the figure)
In the figure, the display electrodes 4 on the second surface (upper substrate) are striped signal electrodes that are perpendicular to the scanning electrodes 3, and the terminal portions 3a of each scanning electrode 3 and the terminal portions (
(not shown) are led out to the outside of the sealing material 7 and arranged on the edge of the substrate 1.2.

This liquid crystal display element displays an image by utilizing the orientation memory property (self-retention property of the orientation state) of the ferroelectric liquid crystal LC, and the liquid crystal When an ON electric field equal to or higher than the threshold electric field is applied, the liquid crystal in the area where the electric field is applied becomes oriented in one direction, and this oriented state is maintained even after the application of the electric field is cut off. In addition, when an OFF electric field (an electric field higher than the threshold electric field of the liquid crystal) in the opposite direction to the driving electric field is applied in this state, the liquid crystal becomes approximately 45° with respect to the previous alignment direction.
``It is oriented in the direction of rotation and maintains this oriented state even after the application of the electric field is cut off.The oriented insulating films 5 and 6 formed on the open substrates 1 and 2 are oriented in parallel directions to each other. The alignment direction of the liquid crystal when the ON electric field or OFF electric field is applied is regulated by the alignment treatment insulating film 5.6.The polarizing plate 8.9 also has a polarization axis (transmission axis or absorption axis). are arranged almost perpendicular to each other.

Furthermore, the directions of the polarization axes of the polarizing plates 8 and 9 are such that the liquid crystal orientation direction when an ON electric field is applied intersects with the polarization axes of both polarizing plates 8.9 at an angle of approximately 45'', and when an OFF electric field is applied, The liquid crystal alignment direction of is almost parallel to the polarization axis of one polarizing plate 8 (almost perpendicular to the polarization axis of the other polarizing plate 9)
Therefore, this liquid crystal display element transmits light when an ON electric field is applied, and blocks light when an OFF electric field is applied. Note that the non-display area B (the area where the display electrodes 3.4 are not facing each other) between the image display area A and the sealing material 7 appears as the outline edge of the image displayed in the image display area A; Since no electric field is applied to the liquid crystal LC in the non-display area B to orient it, the brightness of the non-display area B does not change.

Although a simple matrix type liquid crystal display element is shown in Fig. 4, liquid crystal display elements for displaying television images, etc. also include TPT active matrix type liquid crystal display elements in which pixel electrodes are selected by thin film transistors (TPTs). In this TPT active matrix type liquid crystal display element, thin film transistors and pixel electrodes are arranged vertically and horizontally in the image display area of one substrate, and a single electrode-shaped opposing electrode is formed in the image display area of the other substrate over the entire area. forming an electrode. Furthermore, in the liquid crystal display element shown in FIG.
Aligned insulating films 5 and 6 are provided on each of the open substrates 1 and 2, but some liquid crystal display elements using ferroelectric liquid crystals have an aligned insulating film provided only on one substrate surface. .

By the way, in a liquid crystal display element using this ferroelectric liquid crystal, in order to improve the memory property of the orientation of the liquid crystal LC,
It is desired to reduce the gap (cell gap) between the side substrates 1 and 2 to about 1 p, and in order to equalize the threshold electric field of the liquid crystal over the entire liquid crystal layer,
It is desired that the gaps between the two be uniform.

For this reason, in the conventional liquid crystal display element, spacers 10 such as granular spacers or short cut glass fibers are dispersed between the side substrates 1 and 2 (between the alignment treated insulating films 5 and 6), as shown in FIG. Both substrates 1,
A spacer 11 is also mixed into the sealing material 7 for bonding the substrates 10 and 2, and the gap between the two substrates 10 and 2 is regulated by the spacer 10 and 11.

[Problem to be solved by the invention]

However, in the conventional liquid crystal display element described above, the substrate 1.
The height of the part of the display electrode 3.4 that is bonded by the sealing material 7 on the two sides is different from that of the display electrode 3.4 where the part of the display electrode 3.4 led out to the outside of the sealing material 7 passes through and the other part of the display electrode 3.4. On the other hand, the diameter of the spacer 11 mixed in the sealing material 7 is uniform, so the gap between the substrates 1 and 2 that is regulated by the spacer 11 in the sealing material 7 is There was a problem in that the substrates 1, 2 were distorted differently on the lead-out side of the display electrodes 3, 4 and on the other side, and as a result, the gap between the two substrates 1, 2 could not be made uniform. The threshold electric field of a ferroelectric liquid crystal varies depending on the layer thickness of the liquid crystal layer (the gap between the two substrates 1.2), so conventional liquid crystal display elements where the gap between the two substrates 1.2 is not uniform are , the threshold electric field of each part of the liquid crystal layer was uneven, which caused color unevenness in the displayed image.

Moreover, in the above conventional liquid crystal display element, the height of the substrate 1°2 is the area surrounded by the sealing material 7, that is, the display electrode 3.
, 4 and the alignment-treated insulating film 5.6 are different from the area bonded by the sealant 7, so the spacer 11 mixed in the sealant 7 is used as a seal between the side substrates 1 and 2. It is necessary to use a spacer 10 that is larger in diameter by the thickness of the display electrodes 3, 4 and the alignment treatment insulating film 5.6 than the spacer 10 sandwiched in the area surrounded by the material 7. A spacer of 10°11 was required.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to make the gap between the side substrates uniform, to keep the threshold electric field constant in each part of the liquid crystal layer, and to eliminate color unevenness. A liquid crystal display that can display high-quality images without any blemishes, and also allows the use of the same spacer for the spacer sandwiched between the side substrates in the area surrounded by the sealant and the spacer mixed in the sealant. The purpose is to provide devices.

[Means to solve the problem]

The present invention provides a transparent display electrode in which a terminal portion is led out to the outside of the sealing material in a region surrounded by the sealing material of a pair of transparent substrates that are bonded together via a frame-shaped sealing material containing a spacer. and forming an alignment-treated insulating film on the electrode forming surface of at least one of the substrates, and sandwiching a spacer between the side substrates to regulate a gap between the side substrates, and forming the seal between the side substrates. In a liquid crystal display element in which a ferroelectric liquid crystal is sealed in a gap surrounded by a material, the display electrode and the display electrode are bonded to the parts of the both substrates that are bonded with the seal material, except for the terminal lead-out area of the display electrode. A non-display electrode made of the same transparent conductive film is formed, and the alignment-treated insulating film formed on the electrode formation surface of at least one substrate is also formed over the entire circumference of the part to be adhered with the sealing material. The spacer mixed in the sealing material is characterized in that the spacer has the same diameter as the spacer sandwiched between the side substrates in the area surrounded by the sealing material.

[Effect]

That is, in the present invention, the same transparent conductive conductive material as the display electrode is applied to the parts of both substrates that are bonded with the sealant, other than the part through which the part of the display electrode led out to the outside of the sealant passes. By forming a non-display electrode made of a film, and further forming an alignment-treated insulating film on the electrode formation surface of at least one of the substrates over the entire circumference of the part to be bonded with the sealing material, the side substrate surface The height of the part bonded by the sealant on the side board surface is made equal over the entire circumference, and the height of the part bonded by the sealant on the side board surface and the area surrounded by the sealant is also made equal, and By making the spacer mixed in the spacer have the same diameter as the spacer sandwiched between the side substrates in the area surrounded by the sealing material, the gap between the side substrates can be made uniform.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to FIGS. 1 to 3.

FIG. 1 is a sectional view of a liquid crystal display element, FIG. 2 is a diagram of an electrode pattern on one substrate surface, and FIG. 3 is a diagram of an electrode pattern on the other substrate surface. Note that in FIGS. 1 to 3, parts having the same configuration as the conventional liquid crystal display element shown in FIG. 4 are denoted by the same reference numerals, and redundant explanation will be omitted.

In this embodiment, terminal portions 3a and 4a are respectively led out to the outside of the sealing material 7 in areas surrounded by the sealing material 7 of a pair of transparent substrates 1 and 2 bonded via a frame-shaped sealing material 7. A transparent display electrode 3.4 is formed, and both substrates 1, 2
An alignment-treated insulating film 5.6 is formed on the electrode formation surface of the substrate 1.2, and a spacer 10 is sandwiched between both substrates 1.2 to regulate the gap between the side substrates 1.2. In a liquid crystal display element in which a ferroelectric liquid crystal LC is sealed in a gap surrounded by a sealing material 7, terminal portions of the display electrodes 3.4 are led out at the portions of the side substrates 1 and 2 that are bonded with the sealing material 7. The same transparent conductive film as the display electrode 3.4 except for the area (
For example, a non-display electrode 13.14 made of an ITO film is formed, and the alignment-treated insulating film 5.6 formed on the electrode formation surface of the side substrate 1.2 is also applied to the portion to be bonded with the sealing material 7. A spacer 10a which is formed over the entire circumference and mixed into the sealing material 7 is a spacer having the same diameter as the spacer 10 which is sandwiched in the area surrounded by the sealing material 7 between the side substrates 1°2. .

Note that the alignment-treated insulating films 5 and 6 are connected to the display electrodes 3 and 4.
The alignment treatment insulating films 5 and 6 are continuously formed from the display area A where the image display area A and the sealing material 7 are formed, to the non-displaying area between the image displaying area A and the sealing material 7, and to the part bonded by the sealing material 7. is subjected to alignment treatment similar to that of conventional liquid crystal display elements. Further, on the outer surface of each side substrate 1.2, a polarizing plate 8.9 is arranged with its polarization axis aligned in the same direction as a conventional liquid crystal display element. The liquid crystal display element of this embodiment is of a simple matrix type, and the display electrodes 3 on one side of one substrate (the lower substrate in the figure) are striped scanning electrodes, and the display electrodes 3 on one side of the other substrate (the upper substrate in the figure) ) The display electrodes 4 on the two sides are striped signal electrodes perpendicular to the scanning electrodes 3, and the terminal portions 3a of each scanning electrode 3 on one substrate 1 are led out to the outside of the sealing material 7 and are connected to the substrate. The terminal portions 4a of each signal electrode 4 on the other substrate 2 are led out to the outside of the sealing material 7 and arranged on one side edge of the substrate 2.

Furthermore, among the non-display electrodes 13 and 14, one of the substrates 1
As shown in FIG. 2, the non-display electrode 13 in this example is a planar U-shaped electrode that surrounds three sides of the three groups of scanning electrodes excluding the substrate edge lead-out side, and the non-display electrode on the other substrate 2 side. The electrode 14 is
As shown in FIG. 3, the electrodes are U-shaped in plan, surrounding three sides of the four groups of signal electrodes excluding the lead-out side of the substrate edge. Also,
Both ends of these non-display electrodes 13.14 are led out to the outside of the sealing material 7, and these non-display electrodes 13.1
The lead-out portions 4 are terminal portions 13a for applying an electric field, respectively.
It is said to be 14B. Note that the terminal portions 13a of the non-display electrodes 13 on one substrate 1 side are led out to both sides of the group of terminal portions 3a of each scanning electrode 3, and the terminal portions 14a of the non-display electrodes 14 on the other substrate 2 side are led out to both sides of the group of terminal portions 3a of each scanning electrode 3. The terminal portions 48 of the signal electrode 4 are led out on both sides of the terminal portion 48 group. Further, each of the non-display electrodes 13 and 14 has an outer circumferential edge located slightly inside the outer circumferential surface of the sealing material 7, and an inner circumferential edge extending inward from the inner circumferential surface of the sealing material 7. There is. Note that this non-display electrode 13.
14 is slightly larger than the width of the non-display area B (the distance between the outer circumferential edge of the third group of scanning electrodes and the outer circumferential edge of the fourth group of signal electrodes and the inner circumferential surface of the sealing material 7). The width is small, and the distance between the non-display electrode 13 and the third group of scanning electrodes and the distance between the non-display electrode 14 and the fourth group of signal electrodes are equal to the arrangement interval of each scanning electrode 3 and the arrangement interval of each signal electrode 4. They are approximately the same spacing.

The non-display electrodes 13 on one substrate 1 and the non-display electrodes 14 on the other substrate 2 face each other on two sides, and the non-display electrodes 14 on one substrate 1
The other side of 3 faces the portion of the signal electrode 4 group of the other substrate 2 led out to the outside of the sealing material 7, and the other side of the non-display electrode 14 of the other substrate 2 It faces the portion of the scanning electrode 3 group of the substrate 1 that is led out to the outside of the sealing material 7 .

That is, in the liquid crystal display element of this example, the side substrates 1.2
Of the parts to be adhered with the sealant, the display electrodes 3 and 3 are also attached to other parts than the parts of the display electrodes (scanning electrodes and signal electrodes) 3.4 that are led out to the outside of the sealant 7. , 4. Non-display electrode 13.1 made of the same transparent conductive film as in 4.
4, and furthermore, the alignment-treated insulating films 5 and 6 formed on the electrode formation surface of the side substrate 1.2 are also formed over the entire circumference of the portion to be bonded with the sealing material 7. The height of the part bonded by the sealing material 7 on the two sides is made equal over the entire circumference, and the side substrates 1,
The part bonded by the sealant 7 on the two sides and the sealant 7
The height of the area surrounded by is also the same, and the sealing material 7
The gap between the side substrates 1 and 2 was made uniform by making the spacer 10a mixed therein have the same diameter as the spacer 10 sandwiched in the area surrounded by the sealing material 7 between the side substrates 1 and 2. It is something.

According to this liquid crystal display element, since the gap between the side substrates 1 and 2 is uniform, the threshold electric field in each part of the liquid crystal layer can be kept constant and a high-quality image without color unevenness can be displayed. Moreover, since the same spacer can be used for the spacer 10 sandwiched between the side substrates 1 and 2 in the area surrounded by the sealant 7 and the spacer 10a mixed in the sealant 7, only one spacer is used. All you need is one with a different diameter.

Further, in the conventional liquid crystal display element shown in FIG. 4, the non-display area B between the image display area A and the sealing material 7 has a contour edge with a mottled pattern in which bright areas and dark areas are irregularly mixed. However, in the liquid crystal display element of the above embodiment, the non-display electrodes 13 and 14 are extended to the non-display area B. Since the non-display area B is formed so as to be exposed, the non-display area B can be seen as a -like outline edge without a mottled pattern, and the outline of the image displayed in the display area A can be clearly seen.

In other words, the reason why the non-display area B appears as a mottled outline in conventional liquid crystal display elements is due to the characteristics of ferroelectric liquid crystal, and ferroelectric liquid crystal has two stable alignment states. Therefore, before applying an electric field equal to or higher than the threshold electric field to orient it in one direction, it is oriented in various directions. In the conventional liquid crystal display element, the liquid crystal LC in the image display area A is connected to the display electrode 3.
．． Although the orientation state is controlled by applying an ON electric field and an OFF electric field between the image display area A and the sealing material 7, the electric field that orients the liquid crystal LC in the non-display area B between the image display area A and the sealing material 7 does not act on it. , the liquid crystal LC in this non-display area B remains oriented in various directions. Therefore, in the non-display area B, areas with high light transmittance (bright areas) and areas with low light transmittance (dark areas) are irregularly mixed, and therefore,
This non-display area B appears as an outline edge of a mottled pattern.

On the other hand, in the liquid crystal display element of the above embodiment, the non-display electrodes 13 and 14 are arranged in the non-display area B inside the sealing material 7.
Since the non-display electrodes 13.
14 to apply an electric field to the liquid crystal LC in the non-display area B so that the liquid crystal LC in the non-display area B can also be aligned in one direction.

Note that the liquid crystal display element of this example is driven to display after aligning the liquid crystal LC in the image display area A and the non-display area B in one direction. When an electric field equal to or higher than the threshold electric field of the liquid crystal LC is applied between the electrode 13 and the 4 groups of signal electrodes and the non-display electrode 14 of the other substrate 2, the display area A and the non-display area B
The liquid crystal LC is aligned in one direction over its entire area. The applied electric field at this time is an ON electric field that puts the liquid crystal display element in a light transmitting state, and an OFF electric field that puts the liquid crystal display element in a light blocking state.
An electric field may be used. For example, when an ON electric field is applied, the display area A and non-display area B become bright (white) over the entire area, and when an OFF electric field is applied, the display area A becomes a bright state (white state).
The entire non-display area B becomes dark (black). This orientation of the liquid crystal LC in one direction by applying an electric field is performed when the power is turned on for a display device (for example, a television receiver, etc.) that displays an image using a liquid crystal display element, and the display drive that causes the liquid crystal display element to display an image is performed. After that, the ON electric field and the OFF electric field are applied only between the scanning electrode 3, which is a display electrode, and the signal electrode 4. During this display drive, an electric field equal to or higher than the threshold electric field of the liquid crystal LC is applied between the potential of the non-display electrodes 13.14 and the opposing electrodes (the non-display electrodes 14.14 and the scanning electrodes 13 or the signal electrodes 4). It is sufficient to maintain the voltage at a level where no voltage is applied. If this is done, the liquid crystal LC in the non-display area B will maintain the aligned state by the initially applied electric field due to the memory property of its alignment, so that even during display driving, The entire non-display area B remains bright or dark.

As described above, according to the liquid crystal display element of this embodiment, the non-display area B can be made to appear as a contour edge without the mottled pattern that occurs in the non-display area B of conventional liquid crystal display elements, Therefore, the outline of the displayed image can be clearly seen.

In the above embodiment, the oriented insulating films 5.6 are formed on the electrode forming surfaces of the side substrates 1.2, but the oriented insulating films 5.6 are formed on only one of the side substrates 1 and 2. may be provided. Further, in the above embodiment, in order to also align the liquid crystal LC in the non-display area B in one direction, the non-display electrode 13.
14 is formed by extending into the non-display area B, but if the width of the non-display area B is very small, the mottled pattern at the edge of the outline will not be very noticeable. If a black mask surrounding the display area A is provided, the non-display area B can be covered by this black mask, so in this case, the non-display electrodes 13.14
It is not necessarily necessary to form it so as to extend into the non-display area B. Further, although the liquid crystal display element of the above embodiment is of a simple matrix type, the present invention can also be applied to a TPT active matrix type liquid crystal display element, and furthermore, the present invention can be applied to a liquid crystal display element of red, green, and blue color. The present invention can also be applied to a color liquid crystal display device that displays a full-color image by providing color filters.

〔Effect of the invention〕

In the liquid crystal display element of the present invention, among the parts of the side substrate that are bonded with the sealing material, the parts of the display electrodes that are led out to the outside of the sealing material pass through the parts that are the same as the display electrodes. By forming a non-display electrode made of a transparent conductive film, and further forming an alignment-treated insulating film on the electrode forming surface of at least one of the substrates over the entire circumference of the part to be bonded with the sealing material, both The height of the part of the store board surface that is bonded by the sealant is made equal over its entire circumference, and the height of the part of both store board surfaces that is bonded by the sealant and the area surrounded by the sealant is also made equal;
Furthermore, by making the spacer mixed into the sealant the same diameter as the spacer sandwiched between the two substrates in the area surrounded by the sealant, the gap between the two substrates is made uniform. It is possible to display high-quality images without color unevenness by keeping the threshold electric field constant at each part of the layer.Moreover, it is possible to display a high-quality image without color unevenness by keeping the threshold electric field constant in each part of the layer. Since the same spacer can be used for the spacer mixed in with the spacer, only one diameter of spacer is required.

[Brief explanation of the drawing]

Figures 1 to 3 show an embodiment of the present invention. Figure 1 is a cross-sectional view of a liquid crystal display element, Figure 2 is a diagram of an electrode pattern on one substrate surface, and Figure 3 is a diagram of an electrode pattern on the other side. FIG. 3 is a diagram of an electrode pattern on a substrate surface. FIG. 4 is a cross-sectional view of a conventional liquid crystal display element. 1.2...Substrate, 3...Scanning electrode (display electrode),
3a...Terminal part, 4...Signal electrode (display electrode),
4a...Terminal portion, 5, 6...Oriented insulating film, 7.
...Sealing material, LC...Ferroelectric liquid crystal, 8,9...
Polarizing plate, 10.10a... Spacer, 13.14...
- Non-display electrode, A... display area, B... non-display area. Figure 3 Figure 4

Claims (1)

[Scope of Claims] A transparent display in which a pair of transparent substrates are bonded together via a frame-shaped sealant containing a spacer, and a terminal portion is led out to the outside of the sealant in an area surrounded by the sealant. forming an electrode for the substrate, and forming an alignment treatment insulating film on the electrode forming surface of at least one of the substrates, and sandwiching a spacer between the two substrates to regulate a gap between the two substrates,
In a liquid crystal display element in which a ferroelectric liquid crystal is sealed in a gap surrounded by the sealing material between the two substrates, a terminal portion lead-out region of the display electrode is provided in a portion of both the substrates that is bonded with the sealing material. except for forming non-display electrodes made of the same transparent conductive film as the display electrodes, and applying the alignment-treated insulating film formed on the electrode formation surface of at least one substrate also to the portions to be bonded with the sealing material. A liquid crystal display element, characterized in that the spacer formed over the entire circumference and mixed in the sealing material has the same diameter as the spacer sandwiched in the area surrounded by the sealing material between the two substrates.