JPS63113420A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To preclude color shade even if environmental temperature varies and to obtain superior display quality by providing a electrode for correction even on a substrate surface outside an effective display area and applying this electrode for correction with a voltage whose effective value is equal to that at a nonselection point. CONSTITUTION:Striped transparent electrodes 13 and 23 are formed on an upper sub strate 11 and a lower substrate 21, electrode opposite parts shown by slanting lines from the effective display area 45, and its outer peripheral part is an ineffective display area 47. Transparent electrodes 14 and 24 for correction which are as thick as the transparent electrodes 13 and 23 are provided on even a substrate formed as the ineffec tive display area part 47, and the electrodes 14 and 24 for correction are applied with the voltage which is as high as the effective value voltage at nonselection points when a liquid crystal cell is driven. Therefore, even if applied voltage-brightness characteristics vary under the influence of in-use temperature, the color of the ineffec tive display area 47 is equal to the color of the nonselection points in the effective display area 45. Consequently, the color shade due to a difference in color between the nonselection points in the effective display area and the ineffective display area is eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a 5BE (super twisted birefringence effect) type matrix type using a flexible film substrate in which liquid crystal molecules have a twisted structure of 160 degrees or more between the substrates. Related to liquid crystal display elements.

TN (Twisted Nematic) has been the mainstream until now.
This type of liquid crystal display element is composed of a liquid crystal cell having a liquid crystal layer having a 90-degree twist structure between electrode substrates, and a pair of polarizing plates arranged to sandwich the liquid crystal cell.

However, in recent years, the number of time divisions has increased with the increase in size and density of dot matrix type liquid crystal display elements, and the time division characteristics of conventional TN type liquid crystal display elements are no longer able to cope with the increase in the number of time divisions. .

On the other hand, an SBE type liquid crystal display element in which liquid crystal molecules are twisted by 160 degrees or more between substrates is known, and it has been reported that a high contrast of 1~ can be obtained even during high-order division driving.

In SBE type liquid crystal display elements, when the polarizing plate is fixed, the color changes depending on the product d・Δn of the refractive index anisotropy Δn of the liquid crystal and the thickness d of the liquid crystal layer, but Δn changes depending on the temperature. The color will change accordingly. Furthermore, when a voltage is applied to the liquid crystal cell, the direction of the liquid crystal molecules changes, Δn changes, and the color changes, and the brightness changes due to the color change.

Therefore, due to the difference in Δn-d when no voltage is applied,
Various applied voltage and brightness characteristics occur.

When the liquid crystal cell has applied voltage-luminance characteristics as shown in Figure 5 at room temperature, the color of non-selected points in the effective display area is
The color corresponds to the applied voltage (V = V). on the other hand,
Since no electrodes are provided outside the effective display area, no voltage is applied, and the color of the non-effective display area is the color corresponding to the voltage v=0. When the applied voltage-luminance characteristic is as shown in Figure 5, the colors at ■ = 0 and V = V1 are almost the same, and the difference in color between the non-selected point in the effective display area and the non-effective display amount is not noticeable. .

However, if Δn changes due to changes in the environmental temperature, etc., and the applied voltage-luminance characteristic becomes as shown in FIG. The difference in color in the V-section becomes thicker, and the difference in color between the non-selected point in the effective display area and the non-effective display area becomes noticeable, resulting in color unevenness.

An object of the present invention is to provide an SBE type liquid crystal display element that prevents the occurrence of color unevenness.

In the liquid crystal display element of the present invention, liquid crystal molecules having positive dielectric anisotropy are aligned approximately horizontally with respect to the substrates when no voltage is applied between a pair of substrates forming opposing electrodes in a matrix shape. In a liquid crystal display element having a liquid crystal cell which is sandwiched in this way and has a structure in which the liquid crystal molecules are twisted in the thickness direction between both substrates, and the twist angle is 160 degrees or more, Also, a correction electrode is provided, and a voltage whose effective value voltage is equal to that of the non-selected point is applied to the correction electrode.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

FIG. 1 is a sectional view showing an embodiment of a liquid crystal display element of the present invention, in which a liquid crystal cell IO is sandwiched between an upper polarizing plate 41 and a lower polarizing plate 43.

The liquid crystal cell 10 is formed by sealing liquid crystal 31 between an upper substrate 11 and a lower substrate 21. 15 and 25 are alignment films, 33 is a gap material, and 35 is a sealant.

Furthermore, as shown in FIGS. 2 and 3, the upper substrate 11
Striped transparent electrodes 13.23 made of transparent conductive films are formed on the lower substrate 21 and the lower substrate 21, respectively, and opposing portions of the transparent electrodes 13.23 form a dot matrix. FIG. 4 is a diagram showing a state in which the substrates of FIGS. 2 and 3 are arranged facing each other (the substrates are omitted), and the electrode facing portion shown by diagonal lines forms an effective display area 45, and The outer periphery is an ineffective display area 47.

In the present invention, a correction electrode 14.24 having the same thickness as the transparent electrode 13.23 is also provided on the substrate forming such an ineffective display area portion 47.

This correction transparent electrode 14.24 is connected to a driving circuit board (not shown) so that a voltage equal to the effective value voltage of a non-selected point during driving of the liquid crystal cell is applied. Therefore, even if Δn changes due to the influence of operating temperature, etc., and the applied voltage-luminance characteristic becomes as shown in Fig. 6, for example,
The color of the non-effective display area is equal to the color of the non-selected point in the valid display area.

According to the present invention, in an SBE liquid crystal display element in which an effective display area is formed by matrix electrodes, a correction electrode is also provided on the substrate surface outside the effective display area, and the correction electrode is By applying a voltage whose effective value voltage is equal to that of the non-selected point, color unevenness can be effectively prevented and excellent display quality can be achieved even when the environmental temperature changes.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the liquid crystal display element of the present invention. FIG. 2 and FIG. 3 are perspective views showing the substrate used in the present invention (however, the alignment film is omitted). FIG. 4 is an explanatory diagram showing the state of the transparent electrode and the correction transparent electrode in a state where the substrates are stacked. FIGS. 5 and 6 are graphs showing applied voltage-luminance characteristics. 11... Upper substrate 13, 23... Transparent electrode 14.
24...Correction transparent electrode 21...Lower substrate 45...Effective display area Fig. 1

Claims (1)

[Claims] 1. Liquid crystal molecules with positive dielectric anisotropy are sandwiched between a pair of substrates forming opposing electrodes in a matrix shape so that they are oriented approximately horizontally with respect to the substrates when no voltage is applied. In a liquid crystal display element having a liquid crystal cell in which molecules have a twisted structure in the thickness direction and the twist angle is 160 degrees or more, a correction electrode is also provided on the substrate outside the effective display area, and the correction electrode is A liquid crystal display element characterized in that a voltage whose effective value voltage is equal to the non-selected point is applied to the non-selected point.