JPH0720659Y2 - Liquid crystal display element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Industrial field of application" The present invention relates to a negative display having a black mask in the background.
TN liquid crystal display device.

"Prior Art" A conventional negative display liquid crystal display element includes a display substrate 12 having a transparent electrode 11 formed on the inner surface thereof, as shown in FIG.
A counter substrate 14 having a transparent electrode 13 formed on the inner surface is bonded to face each other with a sealing material 15 in between, and a TN type liquid crystal 16 is provided inside.
Is enclosed and configured as a cell 17. The transparent electrodes 11 and 13 on both substrates are formed of an ITO film or the like having a thickness of about 400 to 500 Å, and are patterned into a predetermined shape. The display pattern is formed by the overlapping portions of the transparent electrodes 11 and 13. Then, on the inner surface of the display substrate 12,
An alignment film 18 is formed so as to cover the transparent electrode 11, a black mask 19 is formed on a portion other than the transparent electrode 13 on the inner surface of the counter substrate 14, and further covers the black mask 19 and the counter electrode 13. An alignment film 20 is formed. The black mask 19 may be formed on the inner surface of the display substrate 12. The black mask 19 is provided to darken the background portion to improve the contrast, and it is necessary to have a thickness of 1 μm or more in order to effectively darken the background portion. The alignment films 18 and 20 are made of a polyimide resin or the like, and have their surfaces subjected to rubbing treatment. Further, on the outside of the display substrate 12 and the counter substrate 14, a polarizing plate 21,
22 are attached with their polarization axes being parallel Nicols.

When this liquid crystal display element is used as, for example, a transmissive type, in a state in which a voltage is not applied between the transparent electrodes 11 and 13, the light of the backlight (not shown) passes through the polarizing plate 22 and the cell 17 Since it enters inside and rotates in the TN liquid crystal 16, it cannot pass through the polarizing plate 21 and forms a dark background portion. Further, in the voltage applied state, the optical rotatory power of the TN liquid crystal 16 disappears, so that the light entering the cell 17 is visually recognized through the polarizing plate 21, and a negative type display is made in the dark background portion. .

[Problems to be solved by the invention] However, in the above liquid crystal display device, the thickness of the black mask 19 on the inner surface of the counter substrate 14 is 1 μm or more, and the thickness of the transparent electrode 13 is about 400 to 500Å. So
Since the thickness difference between the two is at least about 1 μm, the alignment film 20 has a step 20a.

By the way, the TN liquid crystal 16 is aligned in a predetermined direction by the rubbed alignment film 20, but the TN liquid crystal 16 near the step 20a of the alignment film 20 caused by the thickness difference between the black mask 19 and the counter electrode 13 is Liquid crystal aligned on the flat part of the
It will have an unusual angle with respect to the plane compared to 16.
Therefore, the orientation of the liquid crystal in that portion tends to be disturbed, and a tilt domain is easily generated when a voltage is applied.

Moreover, in the above conventional liquid crystal display device, a black mask is used.
Since 19 is formed adjacent to the transparent electrode 13 and the step 20a of the alignment film 20 is located within the width of the transparent electrode 13, the disturbance of the alignment of the TN liquid crystal 16 occurs in the display pattern. Become. Therefore, a tilt domain is generated on the display pattern, which adversely affects the display.

Further, since the black mask 19 is formed adjacent to the transparent electrode 13, for example, when the black mask 19 is to be formed by means of offset printing or the like, alignment is performed to eliminate thinning of the display pattern due to misalignment. Precision is required.

An object of the present invention is to solve the above problems and prevent the occurrence of tilt domains on the display pattern when a voltage is applied due to the disorder of the liquid crystal alignment due to the step of the alignment film.
An object of the present invention is to provide a liquid crystal display device capable of relaxing alignment accuracy when forming a black mask.

[Means for Solving Problems] In a negative display TN liquid crystal display element, a black mask having a thickness of 1 μm or more thicker than the thickness of the electrode pattern is formed on a portion of the inner surface of at least one substrate excluding the electrode pattern. Between the pattern and the black mask
The feature is that a gap of 0.05 to 0.5 mm is provided.

[Operation] As described above, even if the thickness difference between the black mask and the electrode pattern is 1 μm or more, by providing a gap of 0.05 to 0.5 mm between the electrode pattern and the black mask, the thickness of the black mask and the electrode can be improved. The step of the alignment film due to the difference with the thickness of the pixel is located outside the display pattern. Therefore, the portion where the liquid crystal orientation is disturbed due to the step is not located in the display pattern. Therefore, the tilt domain is prevented from occurring in the display pattern, and the display quality is improved. Further, by providing a gap between the black mask and the electrode pattern, the alignment accuracy at the time of forming the black mask is relaxed and the workability is improved.

[Embodiment of the Invention] FIG. 1 shows an embodiment of the liquid crystal display device according to the present invention. The same parts as those in FIG. 2 are designated by the same reference numerals and detailed description thereof will be omitted.

In this liquid crystal display element, a black mask 19 is formed on the inner surface of the counter substrate 14 with a predetermined distance W from the transparent electrode 13. This distance W is set within the range of 0.05 to 0.5 mm. If the distance W is less than 0.05 mm, the effect of the present invention cannot be sufficiently obtained, and if it exceeds 0.5 mm, the effect of the black mask is weakened. The black mask 19 is formed by offset printing a black ink and has a thickness of 1 μm or more. The transparent electrode 13 is made of an ITO film and has a thickness of 400 to 500Å. Therefore, the difference in thickness between the two is about 1 μm or more, and the step 20a is formed on the alignment film 20 formed thereon.
Are formed.

In this liquid crystal display device, the black mask 19 has the transparent electrode 13
Since they are formed apart from each other by a distance W, the step 20a of the alignment film 20 is located outside the pattern of the transparent electrode 13. Therefore, the step 20a in which a tilt domain is generated when a voltage is applied does not affect the display pattern, and the display quality can be kept good.

Further, by providing a gap between the black mask 19 and the transparent electrode 13, it is possible to relax the alignment accuracy when forming the black mask 19. Therefore, even if the transparent electrode 13 has a fine pattern, the black mask 19
It is also possible to prevent the display pattern from becoming thin due to the positional deviation of.

In the gap between the black mask 19 and the transparent electrode 13, light is more likely to be transmitted than in the portion covered by the black mask 19, so it is considered that the brightness of the background portion is uneven, but Since the background portion is sufficiently dark in color by combining the plates 21 and 22, the color tone difference between the portion covered with the black mask 19 and the portion between the black mask 19 and the transparent electrode 13 is not so noticeable. In this case, the polarizing plates 21, 22
If the light transmission amount of either one of them is reduced, the above-mentioned color tone difference becomes less noticeable. Furthermore, it is even more effective if a dichroic dye is added to the TN liquid crystal 16.

The black mask 19 is more accurately a transparent electrode.
Since it is formed on a portion other than the display pattern formed by overlapping 11 and 13, the black mask 19 and the transparent electrode 13 are formed in the portion such as the terminal lead-out pattern of the transparent electrode 13.
And may partially overlap.

Further, in the above embodiment, the black mask 19 may be formed on the inner surface of the display substrate 12. In this case, the transparent electrode
A predetermined gap is provided between the groove 11 and 11.

Further, the above-described embodiment is an example in which the present invention is applied to a transmissive liquid crystal display device, but the present invention further arranges a reflection plate on the back surface of the polarizing plate 22 to reflect external light by this reflection plate. It is also possible to apply it to a reflective type which performs negative display.

[Advantage of Invention] As described above, according to the present invention, even if the thickness difference between the black mask and the electrode pattern is 1 μm or more, a gap of 0.05 to 0.5 mm is provided between the electrode pattern and the black mask. Since it was provided, when forming the alignment film on these,
The step of the alignment film caused by the difference in thickness between the electrode and the black mask is located outside the display pattern. For this reason, the step of the alignment film in which a tilt domain is generated when a voltage is applied does not affect the display pattern, and the display quality can be kept good. In addition, the accuracy of alignment when forming the black mask is relaxed, and the workability can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a liquid crystal display device according to the present invention, and FIG. 2 is a sectional view of a conventional liquid crystal display device. In the figure, 11 is a transparent electrode, 12 is a display substrate, 13 is a transparent electrode, and 14
Is a counter substrate, 16 is a TN liquid crystal, 17 is a cell, 18 and 20 are alignment films,
Reference numeral 19 is a black mask, and 20a is a step.

Claims (1)

[Scope of utility model registration request] 1. A negative TN liquid crystal display device, wherein a black mask thicker than the thickness of the electrode pattern by 1 μm or more is formed on a portion of at least one substrate inner surface excluding the electrode pattern, wherein the electrode pattern and the black mask are provided. A liquid crystal display device characterized in that a gap of 0.05 to 0.5 mm is provided between and.