JPH075477A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To provide the liquid crystal display device with which the uniformalization of the liquid crystal layer thickness over the entire surface of the display dot regions of the liquid crystal display element is possible, the contrast ratio is high and the display state of over the entire part of the screen is uniform without unequal display. CONSTITUTION:The opposite surfaces of two sheets of transparent glass substrates 11, 12 are provided with band-shaped electrodes 31, 32 for display respectively in parallel in such a manner the electrodes of both substrates intersect orthogonally with each other. Oriented films 21, 22 are formed thereon and display dot regions 66 are constituted by the intersected regions. Both substrates are stuck to each other by a sealing material 52 disposed at the marginal circumference between both substrates. A liquid crystal 50 and spacers 68 are sealed between the two substrates and polarizing plates are arranged on the outer side of the substrates. The outer side of the electrodes 31 ', 32 of the outermost array and the parts where the electrodes in the display dot regions 66 do not exist are flattened by using the oriented films 21, 22 in such a manner as to have nearly the same height as the height of the parts where the electrodes exist.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a plurality of strip-shaped display electrodes, which are arranged in parallel, on respective surfaces of two transparent glass substrates facing each other, and display dot areas are formed by intersections of the electrodes. The present invention relates to a liquid crystal display device having a simple matrix liquid crystal display element, and more particularly to a liquid crystal display device capable of suppressing the occurrence of display unevenness.

[0002]

2. Description of the Related Art A conventional twisted nematic type of liquid crystal display device has a 90 ° twisted helix structure made of nematic liquid crystal having a positive dielectric anisotropy between two electrode substrates, and A pair of polarizing plates is arranged outside the electrode substrate such that the polarization axis (or absorption axis) thereof is orthogonal or parallel to the axis of liquid crystal molecules adjacent to the electrode substrate (Japanese Patent Publication No. 13666
Issue).

In such a liquid crystal display device having a twist angle of 90 °, there are problems in the steepness γ of the change in the transmittance of the liquid crystal layer with respect to the voltage applied to the liquid crystal layer and in the viewing angle characteristics. The practical limit was 64 for the number of electrodes). However, in order to cope with recent demands for improving image quality and increasing the amount of display information for liquid crystal display elements, the twist angle α of liquid crystal molecules sandwiched between a pair of polarizing plates is set to be larger than 180 °, and the voltage applied to this liquid crystal layer is increased. Applying physics by TJ Scheffer and J. Nailing to improve the time-division drive characteristics and increase the number of time-divisions by adopting a configuration that detects changes in the birefringence effect of the liquid crystal layer due to
Letter 45, No. 10, 1021, 1984 "Ann Hailey
Multiplexer "(Applied Physics Letter, T.J.
Scheffer, J. Nehring: “A new, highly multiplexabl
e liquid crystal display ”), and a super twisted birefringence effect (SBE) liquid crystal display device has been proposed.

In a liquid crystal display device, for example, two transparent glass substrates are superposed with a predetermined gap so that the surfaces on which the display electrodes made of a transparent conductive film and the alignment film are laminated face each other. A liquid crystal display element in which both substrates are bonded together and a liquid crystal is sealed between both substrates by a sealing material provided around the edge between the substrates, and a polarizing plate is installed or adhered outside the both substrates, and the liquid crystal. A printed circuit board, which is arranged outside the three sides of the display element so as to form substantially the same plane, on which a circuit for driving liquid crystal is formed, and a semiconductor IC for driving liquid crystal.
A plurality of tape carrier packages mounted with chips to electrically connect the liquid crystal display element and the printed circuit board, a backlight arranged below the liquid crystal display element to supply light to the liquid crystal display element, and each of these. It is configured to include a frame-shaped body that is a molded product that holds the members, and a metal frame that houses each of these members and has a liquid crystal display window opened.

Since the STN (Super Twisted Nematic) type liquid crystal display element utilizes the birefringence effect, the color of the transmitted light is determined by the product Δnd of the refractive index anisotropy Δn of the liquid crystal and the thickness d of the liquid crystal layer. Changes. Further, the voltage (threshold voltage V _th ) at which the liquid crystal molecules start to move varies depending on the ratio d / p between the liquid crystal layer thickness d and the twist pitch p of the liquid crystal. _Therefore , even if there is a slight difference in the threshold voltage V _th , display unevenness occurs on the screen. Therefore, making the liquid crystal layer thickness d uniform is a very important factor for the STN type liquid crystal display device.

In a liquid crystal display device having a relatively large area, 2
A small sphere made of an elastic material such as polymer beads is widely used as a spacer for keeping the distance between the substrates constant. However, when the small sphere is an elastic small sphere, there is some variation in the diameter of the spacer. Even if the distribution density is made uniform and pressure is applied from the outside, or if the pressure inside the gap between the substrates is reduced, elastic small spheres with large diameters shrink.
This is because variations in diameter are absorbed and the liquid crystal layer thickness d can be made uniform.

FIG. 13A is a plan view of the liquid crystal display element, and FIG. 13B is a side view thereof.

62 is a liquid crystal display element, 11 and 12 are transparent glass substrates (11 is an upper electrode substrate, that is, a common side electrode substrate, 12 is a lower electrode substrate, that is, a segment side electrode substrate), 52 is a space between both substrates 11 and 12. Is provided around the edge of
Both substrates 11 and 12 are bonded together,
A sealing material made of an epoxy resin for sealing the liquid crystal in the gap between 12, 12, 65 is the position of the display window of the metal frame (see reference numeral 41 in FIG. 10), and 66 (the part with the grid stripes) is both substrates. When viewed from a direction perpendicular to the surfaces 11 and 12, a display dot area formed by areas in which electrodes (not shown here) provided on the opposite surfaces of both substrates 11 and 12 intersect at right angles to each other, 67 is a liquid crystal sealing part using an epoxy resin, 15 is an upper polarizing plate, and 16 is a lower polarizing plate.

FIG. 14 is a partial schematic sectional view of an example of a conventional liquid crystal display element.

Numerals 31 and 32 are strip-shaped transparent electrodes for display (31 is an upper electrode, that is, a common side electrode, 32 is a lower electrode, that is, a segment side electrode) arranged in parallel on the substrates 11 and 12, respectively. The electrodes 31 provided on the substrate 11 and the electrodes 32 provided on the substrate 12 are arranged so as to intersect each other at right angles when viewed from a direction perpendicular to the surfaces of the substrates 11 and 12. 21 and 22 are electrodes 11 and 12, respectively.
An alignment film, which is provided on the surfaces of the substrates 11 and 12 on which the film has been provided and which has been subjected to a rubbing treatment, 50 is a liquid crystal layer, and 68 is an elastic sphere of polymer beads, which is a spacer for keeping the substrate interval constant. .

[0011]

In a large-screen liquid crystal display element used as a display portion of a personal computer, a word processor, or the like, in order to prevent a voltage drop at the ends of the electrodes 31, 32 due to the resistance of the electrodes 31, 32, Electrode 3
The sheet resistance is lowered by increasing the thicknesses of 1 and 32 to about 100 to 200 nm. Therefore, a step difference of about 100 to 200 nm occurs between the display dot area 66 where the electrodes 31 and 32 intersect each other at a right angle and the portion outside the outermost row electrode 31 or 32 where the electrode does not exist. If the spacers made of polymer beads of the same diameter are evenly distributed over the entire surface of the substrate, the display dot area 66 will be displayed even in the display dot area 66.
In other regions, the distance between the two substrates 11 and 12 tends to be almost the same, so that a portion where either one of the electrodes 31 or 32 on the outermost row does not exist (the leftmost electrode in FIG. 13). In the area outside the electrode 31 where the electrodes do not exist), the facing surfaces of the substrates 11 and 12 bend in a direction in which they approach each other (direction indicated by an arrow), and the distance between the substrates 11 and 12 becomes narrower. The shrinkage of the spacer 68 ', which is an elastic small sphere, increases by about several mm inside, as shown in the figure, and the thickness of the liquid crystal layer 50 in this portion decreases.
When the thickness of the liquid crystal layer 50 is reduced, the transmittance is changed from that of other portions, which causes display unevenness.

Further, in the conventional liquid crystal display element, as shown in FIG. 14, the gap between the electrodes 31 is not filled with the alignment film 21, and a groove is formed between the electrodes 31. Since it exists (similarly between the electrodes 32 and 32), when the alignment films 21 and 22 are rubbed, the electrodes 31,
Since the edges of the rubbing cloth disturb the fuzz of the rubbing cloth, the orientation films 21 and 22 of the edges are disturbed in orientation, and a portion called an edge domain in which the orientation direction of the liquid crystal is changed is generated. There was something to do. When the edge domain occurs, the optical characteristics of the transmitted light change at this portion, the display contrast ratio decreases, and the display quality deteriorates.

An object of the present invention is to solve the above-mentioned problems and to provide a liquid crystal display device in which display unevenness and edge domains are less likely to occur and therefore display quality is good.

[0014]

In order to achieve the above-mentioned object, the present invention provides a plurality of strip-shaped display electrodes on opposite surfaces of two transparent glass substrates which are stacked with a predetermined gap therebetween. Are arranged in parallel with each other, and when viewed from a direction perpendicular to the both substrate surfaces, the electrodes provided on one of the substrates and the electrodes provided on the other substrate are intersected at right angles to each other. A display dot region is formed by a region where the electrodes are arranged and the electrodes intersect, and an alignment film subjected to a rubbing treatment is provided on each surface of the substrate provided with the electrodes, and the alignment film is provided around the edge between the substrates. A liquid crystal display element is formed by bonding the both substrates with a sealing material, sealing a liquid crystal and a spacer made of an elastic member between the both substrates, and disposing a polarizing plate outside the both substrates. Liquid crystal display device Te, the partial absence of the outside of the electrodes of the electrode of the outermost row, characterized in that flattened by using an insulating film to be substantially the same height as the portion where the electrode is present.

Further, according to the present invention, the insulating film is used to flatten a portion in the display dot region where the electrode does not exist so as to have substantially the same height as a portion where the electrode exists. Characterize.

Further, the present invention is characterized in that the insulating film is the alignment film.

Furthermore, the present invention is characterized in that at least one phase plate is provided between the polarizing plate and at least one of the substrates.

[0018]

In the present invention, since there is no step between the inside and outside of the display dot area, both glass substrates are bent due to the step as in the conventional case and the distance between the two substrates is narrowed, and the liquid crystal layer thickness within the display dot area is reduced. By making it smaller, it is possible to suppress the occurrence of display unevenness.

[0019]

Embodiments of the present invention will now be described in detail with reference to the drawings.

Example 1 FIG. 1A is a schematic sectional view of a liquid crystal display cell of a first example of the present invention.

11 and 12 are transparent glass substrates (11 is an upper electrode substrate, that is, a common side electrode substrate, 12 is a lower electrode substrate, that is, a segment side electrode substrate), and 31 and 32 are arranged in parallel with the substrates 11 and 12, respectively. The strip-shaped transparent electrode for display (31 is an upper electrode, that is, a common side electrode, 32 is a lower electrode, that is, a segment side electrode) is provided as an electrode 31 provided on the substrate 11 and an electrode 32 provided on the substrate 12. When viewed from a direction perpendicular to the planes of both substrates 11 and 12, they are arranged so as to intersect each other at a right angle. Reference numeral 66 denotes a display dot region (see FIG. 13) formed by a region where the electrodes 31 and 32 of both substrates 11 and 12 intersect each other at a right angle.
21 and 22 are substrates 1 provided with electrodes 11 and 12, respectively.
Alignment films 52 provided on the surfaces 1 and 12 and subjected to a rubbing treatment are provided around the edges between the substrates 11 and 12,
Both substrates 11 and 12 are bonded together,
A sealing material made of an epoxy resin for sealing the liquid crystal between 12, a liquid crystal layer 50, and a spacer 68 made of elastic small spheres of polymer beads, are spacers for keeping the distance between the substrates constant.

In this embodiment, as shown in FIG.
Outside the two electrodes 31 'in the outermost row and the display dot area 66
The portions where the electrodes 31, 31 'do not exist are the electrodes 31,
It is planarized by using the alignment film 21 so as to have the same height as the portion where 31 'exists. That is, the alignment film 21
Is formed so that the portions where the electrodes 31 and 31 'are present are thin and the portions where they are not present are thick, and the thickness obtained by adding the thicknesses of the electrodes 31 and 31' and the alignment film 21 thereon and the presence of the electrodes 31 and 31 '. The thickness of only the alignment film 21 in the non-existing portion is the same,
The entire surface is flat except for the terminals. The substrate 1
The electrode 32 on the second side is not shown, but is not shown in the substrate 1.
Similar to the first side, it is flattened by the alignment film 22. That is, the alignment film 22 is used so that the outside of the two electrodes 32 in the outermost row and the portion in the display dot area 66 where the electrode 32 does not exist have the same height as the portion where the electrode 32 exists. Has been converted.

Embodiment 2 FIG. 1 (b) is a schematic sectional view of a liquid crystal display device according to a second embodiment of the present invention.

In this embodiment, as shown in FIG.
Outside the two electrodes 31 'in the outermost row and the display dot area 66
The inner part where no electrode is present is planarized by using an insulating film, for example, a silicon oxide film (SiO ₂ film) 69 so that it has the same height as the part where the electrodes 31 and 31 ′ are present. Although not shown, the electrode 32 on the substrate 12 side is flattened by the insulating film 70 as on the substrate 11 side. Alignment films 21 and 22 are formed on the insulating films 69 and 70 that are formed flat to have a uniform thickness so that the entire surfaces are flat. After the alignment films 21 and 22 are rubbed, both substrates 11 are formed. , 12 between the liquid crystal layer 50 and the spacer 65.
A liquid crystal cell 60 is produced by sandwiching the liquid crystal cell 60, and a phase plate (birefringent member) composed of a uniaxially stretched film made of polycarbonate is placed on a substrate 11 of the liquid crystal cell 60 and sandwiched by a pair of polarizing plates 15 and 16 to form a liquid crystal. A display element 62 was produced.

In each of the first and second embodiments shown in FIGS. 1A and 1B, since the surfaces of the alignment films 21 and 22 are flat over the entire surface, polymer beads of elastic spheres are used. By uniformly dispersing the spacers 65 made of, for example, on the substrate surface, the distance between the substrates 11 and 12 and the thickness of the liquid crystal layer 50 can be made uniform over the entire surface in the overlapping region of the substrates 11 and 12. .

In the first and second embodiments, the electrodes 31,
FIG. 1 shows a portion with or without 31 'or 32.
As shown in (a) and (b), in order to bury the alignment films 21 and 22 or the insulating films 69 and 70 in a flat manner, these films are applied thickly and then flattened using a squeegee or the like. After smoothing or baking these formed films to cure them, they are flattened by polishing.

Further, the refractive index anisotropy Δn of the liquid crystal and the thickness d of the liquid crystal layer 50 at the portion where the electrode outside the outermost row of electrodes 31 'does not exist and the portion where the electrodes 31 and 31' exist. Since the product Δnd of these is the same, Δnd of the portion outside the outermost row of electrodes 31 is the same as in the conventional liquid crystal display element shown in FIG.
Is larger than the display dot area 66, the display contrast ratio is improved, and the effect is particularly large in the negative mode.

Further, as shown in FIGS. 1A and 1B, in the first and second embodiments, since the surfaces of the alignment films 21 and 22 are flat, the alignment film 21 using a rubbing cloth is used. , 22
Can be satisfactorily performed, the occurrence of the edge domain as described in the conventional example of FIG. 14 can be prevented, and the display quality is improved.

In the liquid crystal display element of the second embodiment of the present invention shown in FIG. 1B and the conventional liquid crystal display element shown in FIG. 14, the same electrode pattern is used and electrodes 31, 32 are formed. The voltage-transmittance characteristic when the thickness was about 200 nm was as shown in FIG. The solid line shows the second embodiment of the present invention, and the broken line shows the conventional example. From FIG. 2 (a),
The contrast ratio when driven with 1/240 duty and 1 / 16.5 bias is as shown in FIG. 2 (b), and the liquid crystal display element of the present invention is about 4 as compared with the conventional one.
It can be seen that the 0% contrast ratio is improved.

FIG. 3 shows a liquid crystal display device 6 to which the present invention can be applied.
2 when viewed from above, the alignment direction of the liquid crystal molecules on the electrode substrate (for example, the rubbing direction), the twist direction of the liquid crystal molecules, the polarization axis (or absorption axis) direction of the polarizing plate, and the optics of the member that causes the birefringence effect. 4 shows an axial direction, and FIG. 4 is a perspective view of a main part of the liquid crystal display element 62.

Twisting direction 10 of liquid crystal molecules and twist angle θ
Is a rubbing direction 6 of the alignment film 21 on the upper electrode substrate 11, a rubbing direction 7 of the alignment film 22 on the lower electrode substrate 12, and a positive dielectric anisotropy sandwiched between the upper electrode substrate 11 and the lower electrode substrate 12. It is defined by the type and amount of the optical rotatory substance added to the nematic liquid crystal layer 50 having the property.

In FIG. 4, in order to align the liquid crystal molecules between the two upper and lower electrode substrates 11 and 12 sandwiching the liquid crystal layer 50 so as to form a twisted spiral structure, a transparent upper layer made of, for example, glass is used. The rubbing method, which is a method of rubbing the surfaces of the alignment films 21 and 22 made of an organic polymer resin made of polyimide, for example, in contact with the liquid crystal on the lower electrode substrates 11 and 12 with a cloth in one direction, is used. ing. The rubbing direction at this time, that is, the rubbing direction, the rubbing direction 6 in the upper electrode substrate 11, and the rubbing direction 7 in the lower electrode substrate 12 are the alignment directions of the liquid crystal molecules. The two upper and lower electrode substrates 1 that have been oriented in this way
1 and 12 are made to face each other with a gap d ₁ so that the rubbing directions 6 and 7 intersect each other at approximately 180 to 360 degrees, and the two electrode substrates 11 and 12 are notched for injecting liquid crystal. When a nematic liquid crystal having a positive dielectric anisotropy and having a predetermined amount of an optical rotatory substance is sealed by bonding with a frame-shaped sealing material 52 having a portion (liquid crystal sealing port) 51, liquid crystal molecules are The molecular arrangement of the spiral structure having the twist angle θ in the figure is arranged between the electrode substrates. 31 and 3
2 is, for example, indium oxide or ITO (Indium
Tin Oxide) is a transparent upper and lower electrode. A member that brings about a birefringence effect on the upper electrode substrate 11 of the liquid crystal cell 60 thus configured (hereinafter referred to as a birefringence member. Fujimura et al. "STN-LCD retardation film", magazine electronic material 1991 2 40 of the month issue, pages 37-41), and upper and lower polarizing plates 15 and 16 sandwiching the member 40 and the liquid crystal cell 60.

The twist angle θ of the liquid crystal molecules in the liquid crystal 50 can take a value in the range of 180 ° to 360 °, but is preferably 200 ° to 300 °, but lighting in the vicinity of the threshold value of the transmittance-applied voltage curve. From the practical viewpoint of avoiding the phenomenon that the state becomes an orientation that scatters light and maintaining excellent time division characteristics, the range of 230 to 270 degrees is more preferable. This condition basically makes the response of the liquid crystal molecules to the voltage more sensitive and acts to realize excellent time division characteristics. In order to obtain excellent display quality and the refractive index anisotropy [Delta] n ₁ of the liquid crystal layer 50 a product [Delta] n ₁ of the thickness d ₁
-D ₁ is preferably set in the range of 0.5 μm to 1.0 μm, more preferably 0.6 μm to 0.9 μm.

The birefringent member 40 acts so as to modulate the polarization state of the light passing through the liquid crystal cell 60, and converts the liquid crystal cell 60 alone from a colored display to a black and white display. Thus the birefringent member 40 refractive index anisotropy [Delta] n ₂ and is extremely important product [Delta] n ₂ · d ₂ of a thickness d _2, preferably 0.8μm from 0.4 .mu.m, more preferably 0.5μm To 0.7 μm.

Further, since the liquid crystal display element 62 uses the elliptically polarized light due to the birefringence, the axes of the polarizing plates 15 and 16 and the optical axis when the uniaxial transparent birefringent plate is used as the birefringent member 40. And the electrode substrate 11 of the liquid crystal cell 60,
The relationship between the liquid crystal alignment directions 12 and 6 is extremely important.

The operation and effect of the above relationship will be described with reference to FIG. FIG. 3 shows an axis of a polarizing plate, an optical axis of a uniaxial transparent birefringent member when the liquid crystal display device having the configuration of FIG. 4 is viewed from above,
3 shows the relationship between the alignment directions of liquid crystal molecule axes of an electrode substrate of a liquid crystal cell.

In FIG. 4, 5 is the optical axis of the uniaxial transparent birefringent member 40, 6 is the alignment direction of the liquid crystal molecules of the birefringent member 40 and the upper electrode substrate 11 adjacent thereto, and 7 is the lower electrode substrate 12. The liquid crystal alignment direction, 8 is the absorption axis or polarization axis of the upper polarization plate 15, 9 is the absorption axis or polarization axis of the lower polarization plate 16, and the angle α is uniaxial birefringence with the liquid crystal alignment direction 6 of the upper electrode substrate 11. The angle β formed by the optical axis 5 of the member 40 is the angle formed by the absorption axis or polarization axis 8 of the upper polarizing plate 15 and the optical axis 5 of the uniaxial transparent birefringent member 40, and the angle γ is the lower polarizing plate 16. Is the angle between the absorption axis or polarization axis 9 of the liquid crystal and the liquid crystal alignment direction 7 of the lower electrode substrate 12.

Here, how to measure the angles α, β, and γ in this specification will be defined. In FIG. 8, an intersection angle between the optical axis 5 of the birefringent member 40 and the liquid crystal alignment direction 6 of the upper electrode substrate will be described as an example. The intersection angle between the optical axis 5 and the liquid crystal alignment direction 6 is shown in FIG.
As shown in FIG. ₂ , it can be represented by φ ₁ and φ ₂ , but in the present specification, the smaller corner of φ ₁ and φ ₂ is adopted. That is, since φ ₁ <φ ₂ in FIG. 8A, φ ₁ is defined as an intersection angle α between the optical axis 5 and the liquid crystal alignment direction 6,
Since φ ₁ > φ ₂ in FIG. 8B, φ ₂ is defined as an intersection angle α between the optical axis 5 and the liquid crystal alignment direction 6. Of course, either one may be adopted when φ ₁ = φ ₂ .

In the liquid crystal display element, the angles α, β and γ are extremely important.

The angle α is preferably 50 ° to 90 °, more preferably 70 ° to 90 °, the angle β is preferably 20 ° to 70 °, more preferably 30 ° to 60 °, and the angle γ is preferably. It is desirable to set each to 0 to 70 degrees, and more preferably to 0 to 50 degrees.

If the twist angle θ of the liquid crystal layer 50 of the liquid crystal cell 60 is in the range of 180 ° to 360 °, the above angle is satisfied regardless of whether the twist direction 10 is clockwise or counterclockwise. α, β, and γ may be within the above range.

In FIG. 4, the birefringent member 40 is disposed between the upper polarizing plate 15 and the upper electrode substrate 11, but instead of this position, the lower electrode substrate 12 and the lower polarizing plate 16 are provided.
It may be disposed between and. This case corresponds to the case where the entire structure of FIG. 4 is inverted.

FIG. 5 is a diagram showing a specific example of the twist angle θ and the like. As shown in the figure, the twist angle θ of the liquid crystal molecules is 240 degrees, and as the uniaxial transparent birefringent member 40, a liquid crystal cell having a parallel orientation (homogeneous orientation), that is, a twist angle of 0 degree was used. Here, the thickness d (μm) of the liquid crystal layer and the helical pitch p (μ of the liquid crystal material added with the optical rotatory substance)
The ratio d / p of m) was set to 0.67. Alignment films 21 and 22
Was used, which was formed of a polyimide resin film and rubbed. The tilt angle (pretilt angle) at which the alignment film subjected to the rubbing process causes the liquid crystal molecules in contact with the alignment film to be tilted with respect to the substrate surface is 4 degrees. The Δn ₂ · d ₂ of the uniaxial transparent birefringent member 40 is about 0.6 μm. On the other hand, Δn ₁ · of the liquid crystal layer 50 in which the liquid crystal molecules are twisted by 240 degrees
d ₁ is about 0.8 μm.

At this time, by setting the angle α to about 90 degrees, the angle β to about 30 degrees, and the angle γ to about 30 degrees, the voltage applied to the liquid crystal layer 50 via the upper and lower electrodes 31 and 32 is increased. When the voltage is below the threshold value, light non-transmission, that is, black display, and when the voltage exceeds a certain threshold, light transmission, that is, white and black display is realized. In addition, the axis of the lower polarizing plate 16 is 50
When rotated 90 degrees from 90 degrees, white display was realized when the voltage applied to the liquid crystal layer 50 was below the threshold value, and black when the voltage was above the threshold value, which was the reverse of the above.

FIG. 6 shows a change in contrast during time-division driving at 1/200 duty when the angle α is changed in the configuration of FIG. Although the contrast was extremely high when the angle α was in the vicinity of 90 degrees, the contrast decreased as the angle deviated. Moreover, when the angle α is small, both the lighting part and the non-lighting part are bluish, and when the angle α is large, the non-lighting part is purple and the lighting part is yellow, and in any case black and white display is impossible. Similar results are obtained for the angle β and the angle γ, but in the case of the angle γ, as described above, when the image is rotated from 50 degrees to 90 degrees, the black and white display is reversed.

FIG. 7 is a diagram showing another specific example of the twist angle θ and the like. The basic structure is the same as the specific example shown in FIG.
However, the twist angle of the liquid crystal molecules of the liquid crystal layer 50 is 260 degrees,
The difference is that Δn ₁ · d ₁ is about 0.65 μm to 0.75 μm. The Δn ₂ · d ₂ of the parallel alignment liquid crystal layer used as the uniaxial transparent birefringent member 40 is about 0.5, which is the same as that in the above-mentioned specific example.
It is 8 μm. The thickness d ₁ (μm) of the liquid crystal layer and the helical pitch p (μm) of the nematic liquid crystal material added with the optically active substance.
And the ratio was set to d / p = 0.72.

At this time, by setting the angle α to about 100 degrees, the angle β to about 35 degrees, and the angle γ to about 15 degrees, the black and white display similar to the first specific example was realized. Also, the reverse black-and-white display is possible by rotating the position of the axis of the lower polarizing plate by 50 to 90 degrees from the above value, which is similar to the first specific example. The tendency with respect to the deviations of the angles α, β, and γ is almost the same as in the first specific example.

In each of the specific examples described above, a parallel alignment liquid crystal cell having no twist of liquid crystal molecules is used as the uniaxial transparent birefringent member 40, but rather a liquid crystal layer in which liquid crystal molecules are twisted by about 20 to 60 degrees is used. There is less color change depending on the angle. Like the above-mentioned liquid crystal layer 50, this twisted liquid crystal layer is formed by sandwiching liquid crystal between a pair of transparent substrates that have been subjected to the alignment treatment so that the alignment treatment directions intersect a predetermined twist angle. It In this case, the bisected angle of the two orientation treatment directions sandwiching the twisted structure of the liquid crystal molecules may be treated as the optical axis of the birefringent member. A transparent polymer film may be used as the birefringent member 40 (uniaxially stretched film is preferable at this time). In this case, PET (polyethylene terephthalate), acrylic resin film and polycarbonate are effective as the polymer film.

Further, although the single birefringent member is used in the above-mentioned embodiments, in addition to the birefringent member 40 in FIG. 4, another birefringent member is provided between the lower electrode substrate 12 and the lower polarizing plate 16. It is also possible to insert a bending member. In this case, Δn ₂ · d ₂ of these birefringent members should be readjusted.

However, as shown in FIG. 9, the upper electrode substrate 11
Red, green, and blue color filters 33R, 33G, 33 on top
B. By providing the light shielding film 33D between the filters, multicolor display is possible. FIG. 7 shows the relationship among the alignment direction of the liquid crystal molecules, the twisting direction of the liquid crystal molecules, the axis direction of the polarizing plate, and the optical axis of the birefringent member in the above specific example.

In FIG. 9, each filter 33
On the R, 33G, 33B and the light shielding film 33D, a smoothing layer 23 made of an insulating material is formed in order to reduce the influence of these irregularities, and then an upper electrode 31 and an alignment film 21 are formed.

FIG. 10 is an exploded perspective view showing a liquid crystal display module 62 in which a liquid crystal display element 62, a drive circuit for driving the liquid crystal display element 62, and a light source are integrated compactly. IC 34 for driving the liquid crystal display element 62
Is mounted on a frame-shaped printed circuit board 35 having a window for fitting the liquid crystal display element 62 in the center. The printed circuit board 35 in which the liquid crystal display element 62 is fitted is fitted in the window portion of the frame-like body 42 formed by plastic molding,
The metal frame 41 is superposed on this, and the claw 43 is bent into the notch 44 formed in the frame-shaped body 42 to fix the frame 41 to the frame-shaped body 42.

A cold cathode fluorescent lamp 36 arranged at the upper and lower ends of the liquid crystal display element 62, a light guide 37 made of an acrylic plate for uniformly irradiating the liquid crystal display cell 60 with light from the cold cathode fluorescent lamp 36, A reflecting plate 38 formed by applying white paint to a metal plate and a milky white diffusing plate 39 for diffusing light from the light guide 37 are fitted into the window portion from the back side of the frame-shaped body 42 in the order of FIG. Be done. An inverter power supply circuit (not shown) for lighting the cold cathode fluorescent lamp 36 is provided with a recess (not shown) provided on the right side rear portion of the frame-shaped body 42. The recess 4 of the reflection plate 38 is provided.
It is located at a position facing No. 5. ). Diffuser 3
9, light guide 37, cold cathode fluorescent lamp 36, and reflector 38
Attaches the tongue piece 46 provided on the reflection plate 38 to the frame-shaped body 42.
It is fixed by bending it in the small edge 47 provided in the.

FIG. 11 is a block diagram of a laptop personal computer using the liquid crystal display module 63 for the display portion, and FIG. 12 is a diagram showing a state in which the liquid crystal display module 63 is mounted on the laptop personal computer 64. In this laptop personal computer 64, the microprocessor 4
The result calculated in 9 is transferred to the liquid crystal display module 63 by the liquid crystal driving semiconductor IC 34 via the control LSI 48.
Is to drive.

As described above, according to the above-mentioned specific example, it is possible to realize a field effect liquid crystal display device having excellent time-division driving characteristics and capable of monochrome and multicolor display.

Although the present invention has been specifically described based on the embodiments, the present invention is not limited to the above embodiments, and it goes without saying that various modifications can be made without departing from the scope of the invention. .

[0057]

As described above, according to the present invention,
Since the liquid crystal layer thickness of the entire display dot area of the liquid crystal display element can be made uniform, it is possible to provide a liquid crystal display device having a high contrast ratio, a uniform display state on the entire screen and high display quality without display unevenness. it can.

[Brief description of drawings]

1A is a schematic sectional view of a liquid crystal display cell according to a first embodiment of the present invention, and FIG. 1B is a schematic sectional view of a liquid crystal display element according to a second embodiment of the present invention.

FIG. 2A is a diagram showing voltage-transmittance characteristics of the present invention and conventional liquid crystal display elements, and FIG. 2B is a diagram showing voltage-contrast characteristics of the present invention and conventional liquid crystal display elements.

FIG. 3 is an explanatory diagram showing an example of a relationship among an alignment direction of liquid crystal molecules, a twisting direction of liquid crystal molecules, a direction of an axis of a polarizing plate, and an optical axis of a birefringent member in a liquid crystal display device to which the present invention is applicable. .

FIG. 4 is an exploded perspective view of a main part of an example of a liquid crystal display element.

FIG. 5 is an explanatory diagram showing a relationship among a twist direction of liquid crystal molecules, a direction of an axis of a polarizing plate, and an optical axis of a birefringent member in a liquid crystal display element of another example.

FIG. 6 is a graph showing contrast, transmitted light color-crossing angle α characteristics for the example of the liquid crystal display element shown in FIG. 3;

FIG. 7 is an explanatory diagram showing a relationship among an alignment direction of liquid crystal molecules, a twisting direction of liquid crystal molecules, a direction of an axis of a polarizing plate, and an optical axis of a birefringent member in a liquid crystal display element of still another example.

FIG. 8 is a diagram for explaining how to measure intersection angles α, β, and γ.

FIG. 9 is a partially cutaway perspective view of an example of an upper electrode substrate portion of a liquid crystal display element.

FIG. 10 is an exploded perspective view of an example of a liquid crystal display module.

FIG. 11 is a block diagram of an example of a laptop personal computer.

FIG. 12 is a perspective view of an example of a laptop computer.

13A is a plan view of a liquid crystal display element, and FIG. 13B is a side view thereof.

FIG. 14 is a partial schematic cross-sectional view of an example of a conventional liquid crystal display element.

[Explanation of symbols]

11, 12 ... Transparent glass substrate, 15 ... Upper polarizing plate, 16 ...
Lower polarizing plate, 21, 22 ... Alignment film, 31, 32 ... Transparent electrode, 31 '... Outermost row transparent electrode, 40 ... Phase plate, 50 ...
Liquid crystal layer, 52 ... Sealing material, 60 ... Liquid crystal cell, 62 ... Liquid crystal display element, 66 ... Display dot area, 68 ... Spacer, 6
9, 70 ... Insulating film.

Claims (4)

[Claims] 1. A plurality of strip-shaped display electrodes are arranged in parallel on each of the opposing surfaces of two transparent glass substrates which are superposed with a predetermined gap therebetween, and are arranged perpendicular to the both substrate surfaces. When viewed from a direction, the electrodes provided on one of the substrates and the electrodes provided on the other substrate are arranged so as to intersect each other at a right angle, and a display dot region is formed by a region where the electrodes intersect. Then, an alignment film subjected to a rubbing treatment is provided on each surface of the substrate provided with the electrodes,
A sealing material provided around the edge between the two substrates bonds the two substrates together, seals a liquid crystal and a spacer made of an elastic member between the two substrates, and a polarizing plate is provided outside the both substrates. In a liquid crystal display device having a liquid crystal display element having the above-mentioned arrangement, the portion outside the outermost row of the electrodes where the electrode does not exist is insulated so as to have substantially the same height as the portion where the electrode exists. A liquid crystal display device characterized by being flattened using a film. 2. The insulating film is flattened so that a portion where the electrode does not exist in the display dot region has substantially the same height as a portion where the electrode exists. Item 3. The liquid crystal display device according to item 1. 3. The liquid crystal display device according to claim 1, wherein the insulating film is the alignment film. 4. The liquid crystal display device according to claim 1, wherein at least one phase plate is provided between the polarizing plate and at least one of the substrates.