JPH0247632A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To improve the visibility by devising the shape of a dummy electrode formed except at a display pattern part and erasing the window-shaped display at the outer peripheral part of the display pattern. CONSTITUTION:This device is equipped with 1st and 2nd substrates 1 and 2 where groups of X and Y electrodes 3 and 4 for the display pattern are formed on the sides of 1st main surfaces 1a and 2a, nematic liquid crystal 13 sandwiched between both substrates 1 and 2, and 1st and 2nd polarizing plates 14 and 15 adhered on the sides of the 2nd main surfaces 1b and 2b of the 1st and 2nd substrates 1 and 2. Further, the device has a display part 21 which makes a display by applying a voltage between the X and Y electrodes 3 and 4 as a display range and a background part 20 other than the display part 21, and a part where additional X and Y electrodes 3a and 4a cross each other across a specific gap is provided on the area except the display range consisting of the display part 21 and 20, e.g. a seal part. Consequently, blue of the window frame part of, for example, a blue mode type liquid crystal display device is erased completely. Consequently, the visibility is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a liquid crystal display that utilizes interference colors caused by, for example, birefringence.

(Prior Art) Liquid crystal displays are used in a wide range of applications because of their characteristics of low power consumption, small size, and light weight.

Recently, in addition to the previously used twisted nematic type, the twist angle of liquid crystal molecules has been increased to 180.
With the development of a liquid crystal display with a birefringence mode of more than °,
It has become possible to display large amounts of data for computers, word processors, etc., and its applications are expanding.

With the expansion of such uses, there is a strong demand for backlit LCD devices with a lighting device built into the back of the LCD display for use as displays for personal computers and workstation terminals. A liquid crystal display device incorporating a type of liquid crystal display and a cold cathode discharge tube or an electroluminescence (E) panel for rear illumination has been developed and commercialized.

By the way, such a blue mode type liquid crystal display displays blue in the part where no voltage is applied or in the part where a voltage lower than the threshold voltage of the liquid crystal is applied.
The color becomes almost transparent in the area where a voltage higher than the threshold voltage of the liquid crystal is applied. Therefore, in order to achieve a blue display on a white background, it is necessary to use the reverse mode, that is, to apply an effective value voltage higher than the threshold voltage of the liquid crystal to the part of the display that does not display characters, etc. (non-lit part), and to display the characters. It is necessary to adopt a method of applying an effective value voltage lower than the threshold voltage to the display section (lighting section). As a result, no voltage is applied to the portion of the liquid crystal display where the display electrodes do not exist, that is, the background portion, so that a blue window frame-like portion remains. In this case, when characters, etc. are displayed on the outermost periphery of the display section, the blue color of the character display section and the blue color of the background section become almost the same color, making it difficult to read the characters, etc., which is a problem.

Therefore, in order to solve this kind of problem, for example, in the liquid crystal display described in Japanese Patent Application Laid-Open No. 62-229233, a dummy electrode similar to the display part is provided in the background part, and this dummy electrode is constantly kept in a predetermined position. It is practiced to apply a voltage of .

(Problem to be Solved by the Invention) However, in this conventional example, in order to make the color of the background part as close as possible to the color of the non-lit part in the display part, for example, a dummy electrode formed on one electrode has a high absolute value. When a voltage is applied, the color of a portion of the background portion becomes close to the color of the lighting portion of the display portion, and visibility as a liquid crystal display device may deteriorate.

This invention was made in view of such conventional circumstances.

[Structure of the Invention] (Means for Solving the Problems) The present invention comprises first and second substrates each having a group of X and Y electrodes for a display pattern formed on the first main surface side, and the first substrate. and a nematic liquid crystal sandwiched between a second substrate, and first and second polarizing plates respectively adhered to the second main surface sides of the first and second substrates,
It has a display section that performs display by applying a voltage between the Y electrodes and a background section other than this, and the effective value of the voltage applied to the lighting section of the display section is the voltage applied to the non-lighting section of the display section. It is related to liquid crystal displays that lower the effective value of . According to the present invention, the portion where the above-mentioned additional X and Y electrodes intersect with a predetermined gap is provided in an area excluding the display range consisting of the display portion and the background portion.

(Function) This invention aims to make the color of the background part as similar as possible to the color of the non-lit part of the display part, and the above-mentioned dummy electrodes intersect with each other with a predetermined gap in color. This method focuses on the phenomenon that dummy electrodes are more likely to occur, and by devising the shape of the dummy electrode, this part is provided outside the display range, for example, in the seal part. As a result, it is possible to completely eliminate the blue color in the window frame portion of a blue mode type liquid crystal display, for example.

(Example) The details of this invention will be explained below with reference to the drawings.

Fig. 1 is a diagram for explaining one embodiment of the present invention, Fig. 1 (a> is a plan view, Fig. 1 (b) is a plan view,
It represents a cross-sectional view of the AA' plane when viewed from the direction of the arrow. In FIG. 1, on first and second substrates 1 and 2 made of glass, for example, there are groups of X and Y electrodes 3 and 4 for display patterns made of ITO (indium tin oxide), and additional and Y electrodes 3a, 4
a is formed. Here, − in FIG. 1(a)
The area surrounded by the dashed dotted line 5 indicates a display range that is visible from outside the set, such as a personal computer, when used as a display device, and this display range further includes additional X and Y electrodes 3a, It is divided into a peripheral background area where 4a exists and a display area where the X and Y electrodes 3 and 4 intersect except for this area.

In FIG. 1(b), X and Y electrodes 3 and 4 are provided on the first main surfaces 1a and 2a sides of the first and second substrates 1゜2, respectively.
group and additional X and Y electrodes 3a.

An alignment film 1 made of polyimide, for example, is placed so as to cover 4a.
0.11 is formed, and the periphery thereof is sealed with a sealant 12 made of, for example, an ultraviolet curing adhesive. A nematic liquid crystal 13 doped with a chiral agent is sandwiched between the first and second substrates 1.2.
Due to the action of the chiral agent, the molecular axis ranges from 180° to 360° between the first and second substrates 1 and 2, for example, 210°.
It has a twist of 1° with respect to the first principal surfaces 1a and 2a.
It has a pretilt angle of 3° or more, for example. Also,
On the second main surface 1b side of the first substrate 1, a first@light plate 14 and a second
A second polarizing plate 15 and a reflecting plate 1 are disposed on the second main surface 2b side of the substrate 2.
6 is coated. Here, the first and second polarizing plates 14
．． 15, the transmission axis of the first polarizing plate 14 is in the range of 20' to 40'' clockwise with respect to the alignment direction of the first substrate 1, for example, the transmission axis of the second polarizing plate 15 is in the range of about 30''. Board 2
It is set so that it is in the range of 50'' to 70' clockwise with respect to the orientation direction of, for example, about 60''. A liquid crystal display of the blue mode type is thus obtained, which exhibits a transmissive state when selected and is blue when not selected. In this liquid crystal display, the visibility is better when the part that does not display characters etc. is in a transparent state and the display is blue, so the effective value of the applied voltage in the part that does not display the effective value of the applied voltage in the part that does not display. lower than the effective value.

As can be seen from FIG. 1(a), the shape of the additional X and Y electrodes 3a and 4a is such that one line branches into two from the middle, and a predetermined gap (first and second The intersection of the additional X and Y electrodes 3a and 4a with the gap between the substrates 1 and 2 can be set outside the display range, for example inside the sealant 12, by making the additional X electrode 3a partially bent. are doing.

As a result, the background portion becomes a region where the additional X electrode 3a and the Y electrode 4, or the additional Y electrode 4a and the X electrode 3 intersect with a predetermined gap. It is possible to realize a blue mode type liquid crystal display device that displays blue characters on an entirely white background.

Fig. 2 is a plan view corresponding to Fig. 1(a) in a conventional example (the form described in JP-A No. 62-229233), and corresponding parts are given the same reference numerals. .

As can be seen from the figure, the additional X and Y electrodes 3a and 4a intersect with each other with a predetermined gap at the corners of the background.

FIG. 3 is a diagram showing an example of the drive voltage waveforms in this embodiment (FIG. 1) and the conventional example (FIG. 2), and FIG.
(d) shows the Y electrode 4, the X electrode 3, the additional X electrode 3a, and the additional Y electrode 4a. In Figure 3,
Drive at 1/15 bias, (Vl - V2
) = (V2-V3) = (V4-V5) =
(V5-V6) = (Vl-V6)/15.
(V3-V4) =11- (Vl-V6)
/15. To explain in detail each waveform in FIG. 3, as shown in FIG.
1 and the non-selection voltage is ■5. A voltage that switches every frame is applied to the X electrode 3, as shown in FIG. 3(b), when either voltage V1 or voltage V3 is selected. When either voltage v6 or voltage 4 is selected, a voltage that changes every frame is applied.

Furthermore, as shown in FIGS. 3(C) and (d), the voltages applied to the additional X and Y electrodes 3a and 4a are
It is an alternating voltage having a predetermined potential difference that is approximately equal on both sides centered on the intermediate potential ((Vl - V6)/2) between the maximum value ■1 and the minimum value ■6 of the voltage levels applied to the electrodes 3 and 4, The wave height values are different from each other.

By the way, FIG. 3(C) shows examples of the voltages applied to the additional X electrode 3a: A (voltage V7 and voltage VIO are switched every frame) and 8 (voltage V7 is switched every frame).
1 and voltage V6), but in order to bring the lighting state of the intersection of the additional X electrode 3a and the Yli electrode 4 in the background part as close as possible to the non-lighting part in the display part, As for the voltage waveform, B is more desirable than A. Therefore, the voltage applied to the additional XI pole 3a is set to 8
In this case, the voltage applied to the intersection of the additional X and additional Y electrodes 3a and 4a becomes larger than necessary, and in the conventional example shown in FIG. 2 where this intersection exists in the background,
Therefore, it is impossible to achieve the purpose of making the display state of the background part and the non-lit part of the display part similar. On the other hand, in the embodiment shown in FIG.
Since the intersection of the electrodes 3a and 4a is set outside the display range, this intersection becomes invisible on the display, making it possible to realize a blue mode type liquid crystal display that displays blue characters on an entirely white background. .

FIG. 4 is a diagram showing the situation when the letter T is displayed in the peripheral area of a liquid crystal display that has the same configuration as this embodiment or the conventional example and performs positive display in blue mode. Figure (a) shows the case where the additional X and Y electrodes 3a, 4a are not present, and Figure (b) shows the case of the structure shown in Figure 2 (the additional (C) corresponds to the embodiment shown in FIG. 1. As can be seen from FIG. 4, in FIG. 4(a), the background section 20 and the lighting section of the display section 21 are of the same color as indicated by hatching, and the letters T and 1 are easily confused. In b), there is a color difference between the corner portion 22 and the other portions of the background portion 20, making it difficult to identify the character ”Dou” as well. On the other hand, as can be seen from FIG. 4(C), in this embodiment, a uniform display state is obtained in the background part 20 and the non-lit part of the display part 21, and the character "KING" becomes easy to see.

[Effects of the Invention] This invention makes it possible to completely eliminate the window frame-like display on the outer periphery of the display pattern, which is a problem in reverse mode display, by devising the shape of the dummy electrode formed outside the display pattern. , the visibility of the liquid crystal display is improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining one embodiment of the present invention, and FIG.
The figure is a plan view showing an example of a conventional liquid crystal display, FIG. 3 is a diagram showing an example of the voltage waveform applied to the electrodes in the present invention and the conventional example, and FIG. 4 is the letter T in the present invention and the conventional example. FIG. 1... First substrate 2... Second substrate 1a, 2a... First main surface 1b, 2b... Second main surface 3... X electrode 3a... Additional X electrode 4...・Y electrode 4a...Additional Y electrode 13...Nematic liquid crystal 14...First polarizing plate 15...Second polarizing plate 20...Background section 21...Display section agent Patent attorney Nori Chika Ken Yudo Kikuo Takehana Figure 1 Figure 1

Claims (1)

[Claims] First and second substrates each having a group of X and Y electrodes for a display pattern formed on a first main surface side;
A nematic liquid crystal sandwiched between the substrates and the first
and a first and second polarizing plate respectively adhered to the second main surface side of the second substrate, and a display section that performs display by applying a voltage between the X and Y electrodes as a display range; In a liquid crystal display having a background part other than the above, the effective value of the voltage applied to the lighting part of the display part is lower than the effective value of the voltage applied to the non-lighting part of the display part, A liquid crystal characterized in that additional X and Y electrodes are formed on corresponding first and second substrates, respectively, and a portion where the additional X and Y electrodes intersect with a predetermined gap is provided outside the display range. display.