JPS61278827A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To prevent a non-display area from being darkened and to improve the quality of display by setting up the direction of the polarizing axis of one polarizing plate out of two polarizing plates between which a liquid crystal cell is held differently in a display area and a non-display area. CONSTITUTION:The liquid crystal cell 13 obtained by sealing liquid crystal 12 between two glass substrates 11,11' is held between upper and lower polarizing plates 14,14' and the polarizing axis P1 of a display area of one polarizing plate 14 which corresponds to a display area 13a of the liquid crystal cell 13 is set up in the same direction as the polarizing axis P2 of the other polarizing plate 14'. On the other hand, the polarizing axis P1' of a non-display area 14b of the polarizing plate 14, i.e. a part corresponding to an area having no relation to a driving signal in the liquid crystal cell 13, is set up to the direction rectangular to the polarizing axis P1 of the display area 14a. The polarizing plate 14 is separated into a display area 14a part having the polarizing axis P1 and a non-display area 14b part having the polarizing axis P1' and respective parts 14a, 14b are adhered to the glass substrate 11 like one plate so that their polarizing axes P1, P1' are intersected with each other to form the polarizing plate 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display element used in a display section of electronic equipment such as a calculator, a measuring instrument, a personal computer, and a word processor.

[Prior art]

Currently, the twisted nematic type shown in FIGS. 9(a) and 9(b) is the mainstream liquid crystal display element used in the display section of the above-mentioned electronic equipment.

This twisted nematic liquid crystal display element consists of two glass substrates 1 and 1' whose surfaces have been treated so that rod-shaped liquid crystal molecules are uniaxially aligned along the glass surfaces, as shown in FIGS. 9(a) and 9(b). are arranged facing each other so that their axial directions are perpendicular to each other, and a liquid crystal 2 is sealed between the glass substrates 1 and 1' to form a liquid crystal cell 3. Furthermore, this liquid crystal cell 3 is connected to two polarizing plates 4 and 1'. 4'.

With the above configuration, the liquid crystal cell 3 can twist the alignment direction of the liquid crystal molecules as shown in FIG. 9(a) when no electric field is applied.
While exhibiting optical rotation, which rotates the plane of polarization of incident light by 90 degrees,
When a voltage higher than the threshold value is applied, the liquid crystal molecules change alignment in the direction of the electric field and lose their optical rotation, as shown in FIG. 9(b).

As shown in Figure 9(a)(b), two polarizing plates 4 and 4'
are arranged so that their polarization axes P and P2 are orthogonal to each other, the incident light 5 is optically rotated by the liquid crystal cell 3 as shown in FIG. However, when a voltage higher than the threshold is applied,
Two polarizing plates 4 and 4' whose polarization axes PI and P2 are orthogonal to each other
Therefore, the incident light 5 is cut off as shown in FIG. 9(b). Due to this effect, bright and dark contrast can be obtained on the display screen depending on the voltage applied from the outside,
Desired characters, patterns, etc. are displayed digitally.

In the above configuration, the polarization axes P of the two polarizing plates 4 and 4' are
Pt are set to be orthogonal to each other, but if the polarization axes P1 and P2 are aligned in the same direction, the liquid crystal cell 3
shows optical rotation. When no voltage is applied, the incident light 5 is cut,
Since the light is transmitted when a voltage is applied, the contrast of brightness and darkness in response to the application of an external voltage is opposite to that in the previous case.

The above is a description of a case where a transmissive panel is constructed, and the display surface appears dark in the portion where the incident light is transmitted, and bright in the portion where the incident light is cut off.

On the other hand, in the case of a reflective type structure in which a reflective plate is disposed on the lower surface of the liquid crystal display element, on the contrary, the portion through which the incident light is transmitted appears bright, and the portion where the incident light is cut appears dark. Therefore, by selecting these configurations, either the positive display (display area is black, background is white) shown in Fig. 10 or the negative display (display area is white, background is black) shown in Fig. 11 can be performed. I can do it.

By the way, in a reflective configuration, when a negative display is used, the background, which has a wider surface area than the display area, forms a dark area where the incident light is cut off, so the amount of incident light decreases and the overall display surface becomes dark, which deteriorates the display quality. Therefore, in the case of this reflective type configuration, it is customary to set the display to positive.

In order to perform positive display with the above-mentioned reflective configuration, there is a method of arranging two polarizing plates sandwiching a liquid crystal cell so that their polarization axes are orthogonal to each other, as shown in FIGS. 12(a) and (b). The polarization axes P+'Pz of the two polarizing plates 4 and 4' are aligned in the same direction as shown in FIG. There is a method using the background as a background.

However, in the case of positive display using the latter method, as shown in Fig. 13, incident light is always cut off in the non-display area (a part unrelated to the drive signal surrounding the display area), so this area becomes dark and displays a negative image. This has the disadvantage that the amount of incident light decreases and the display quality deteriorates, as in the case of .

[Purpose of the invention]

An object of the present invention is to provide a liquid crystal display element that can obtain good display quality in the above-mentioned case where positive display is performed using a reflective configuration.

[Structure of the invention]

The liquid crystal display element of the present invention is a Leysten nematic type liquid crystal display element, and the direction of the polarization axis of one of the two polarizing plates sandwiching the liquid crystal cell is set to the display area and the non-display area of the polarizing plate. This feature is characterized in that the display quality is improved by making the non-display %'JIM different from each other, thereby preventing the non-display %'JIM from becoming dark.

[Example 1] A first example of the present invention will be described below based on FIGS. 1 to 6.

FIG. 1 is a perspective view showing the schematic structure of a Leysten nematic type liquid crystal display element according to this embodiment. It is sandwiched between two upper and lower polarizing plates 14 and 14', and one of the polarizing plates 14 has a display area 13 of the liquid crystal cell 13.
The polarization axis P in the display area 14a corresponding to a is aligned in the same direction as the polarization axis P2 of the other polarizing plate 14', while the non-display area 14b of the polarizing plate 14, that is, the liquid crystal cell 13, is a polarization axis p in a portion corresponding to a region where there is no display (a portion surrounding the display area 14a);
l is set in a direction perpendicular to the polarization axis PI of the display area 14a.

FIG. 2 shows a plan view of the polarizing plate 14 in which the polarization axes P, *p, and J are in two directions. This polarizing plate 14
As shown in the figure, when cutting out a portion of the display area 14a having the polarization axis P+ and a portion of the non-display area 14b having the polarization axis PI', and pasting them into a single plate on the glass substrate work 1, It can be formed by setting the polarization axes P, .p and I to be perpendicular to each other.

In addition, when creating the polarizing plate 14, a single plate is divided into a display area 14a of the polarizing axis PL and a non-display area 14b of the polarizing axis P1' by a printing method, and the resulting single plate polarizing plate 14 can also be directly attached onto the glass substrate 11 as shown in FIG.

The liquid crystal cell 13 is provided with electrode lead wires 15a and 15b that scan vertically and horizontally, as shown in FIG. The display area 13a
It is configured to do the following.

When a reflective panel is constructed using this liquid crystal display element,
Since the polarizing axis P of the display area 14a of one polarizing plate 14 and the polarizing axis P2 of the other polarizing plate 14' are aligned in the same direction, one side of the display area 14a that applies a voltage to the portion corresponding to the background By not applying voltage to the portion corresponding to the display, a positive display in which the background is white and the display portion is black is realized. Furthermore, since the polarization axes p and L of the non-display area 14b of one polarizing plate 14 are in the direction perpendicular to the polarization axis Pg of the other polarizing plate 14', the transmission of incident light is always allowed in this non-display area 14b. and appears white. Therefore, as shown in FIG. 4, the entire display surface is white except for the display portion, and good display quality can be obtained.

[Example 2] A second example of the present invention will be described below based on FIGS. 7(a) and 8(b) and FIG.

The liquid crystal display element of this example is an liquid crystal display element in which the present invention is applied to a liquid crystal display element in which the polarization axes of two polarizing plates sandwiching a liquid crystal cell are aligned in the same direction to enable negative display through a reflective configuration. In one of the two polarizing plates 24-24' shown in FIGS. 7(a) and 7(b),
The display area 24a is a part that is slightly wider than the area to be realized as a display area, and the polarization axis P1 of this display area 24a is aligned in the same direction as the polarization axis P2 of the other polarizing plate 24'. The polarization axis p, / of the area other than the display area 24a, that is, the non-display area 24b, is set to the other polarizing plate 24.
' is set in a direction perpendicular to the polarization axis pt.

With this configuration, the black foreground part in the negative display surrounds the white display part in a shading pattern, and most of the remaining surface area is always in a light-transmitting state and appears white. As shown in the figure, the entire display surface becomes brighter, and the display quality is significantly improved.

〔Effect of the invention〕

The liquid crystal display element of the present invention is a Leysten nematic liquid crystal display element in which the direction of the polarization axis of one of the two polarizing plates is made different between the display area and the non-display area of the polarizer. For example, even when a reflective panel is configured to perform positive display, transmission of incident light is allowed in the non-display area, making the entire display surface brighter and improving display quality.

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically showing the first embodiment of the present invention, FIG. 2 is a plan view of one of the polarizing plates, FIG. 3 is a plan view showing the electrode lead wire arrangement part of the liquid crystal cell, and FIG. Figure 4 is a plan view showing the positive display state of the display surface, Figure 5 is an explanatory diagram showing the procedure for forming a polarizing plate, Figure 6 is an explanatory diagram showing another example of the procedure for forming a polarizing plate, and Figure 7. (a) and (b) are plan views showing the polarizing plate of the second embodiment of the present invention, FIG. 8 is a plan view showing the negative display state of the display surface, and FIGS. An explanatory diagram showing the principle of display operation of a stained nematic liquid crystal display element, Fig. 10 is an explanatory diagram showing a positive display state, Fig. 11 is an explanatory diagram showing a negative display state, and Figs. 12 (a) (b). )
13 is an explanatory diagram of a conventional example showing the directions of the polarization axes of two polarizing plates when positive display is performed in a reflective configuration, and FIG. 13 is an explanatory diagram showing the state of positive display. 11 and 11' are glass substrates, 12 is a liquid crystal, 3 is a liquid crystal cell, 13a is a display area, 14, 14', 24, 24'
is a polarizing plate, 14a and 24a are display areas, and 14b and 24b
is the non-display area, P, -P,'・P2 is the polarization axis, 15a・
15b is an electrode lead wire. Figure 1 Figure 2 Figure 3 Figure 4 Figure 6 Figure 7 Figure 8 Figure 9 (a) (b) Figure 10 Figure 11 [ Figure 13

Claims (1)

[Claims] 1. In a twisted nematic liquid crystal display element,
1. A liquid crystal display element characterized in that one of two polarizing plates sandwiching a liquid crystal cell has a polarization axis in a direction different between a display area and a non-display area of the polarizer.