JPS5825247B2 - liquid crystal display element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal display element, and particularly to a liquid crystal display element in which the resistance value of electrodes themselves formed on opposing inner surfaces of a substrate is substantially reduced.

In general, liquid crystal display elements perform display by filling liquid crystal between opposing electrodes and applying a voltage between the opposing electrodes selected in accordance with the pattern to be displayed, making use of optical changes that occur in the liquid crystal. Display element, power consumption,
Because the driving voltage is extremely low, the shape of the display pattern can be freely designed, and it can be constructed into a thin shape, it is widely used for displaying numbers, characters, and symbols in calculators and digital watches.

FIG. 1 is a perspective view of the main parts of an example of a conventional liquid crystal display element, and FIG. 2 is an exploded view of the main parts of FIG.

In these figures, an upper plate electrode 3 and a lower plate electrode 4 of a predetermined shape pattern made of a transparent conductive film are respectively formed on the opposing inner surfaces of an upper plate substrate 1 and a lower plate substrate 2 made of translucent glass and arranged to face each other. Adhesion is formed, and furthermore,
An alignment film (not shown) is formed on the opposing surfaces of the lower plate electrodes 3 and 40.

In addition, as shown in FIG. 2, one end of the lower electrode 3 formed on the inner surface of the upper substrate 1 is extended to the end of the upper substrate 1, and an upper electrode terminal (hereinafter referred to as A terminal (referred to as an upper plate terminal) 5 is formed.

Further, one end of the lower electrode 4 formed on the inner surface of the lower substrate 2 extends to the end of the lower substrate 2 to form a vertical connection portion 6.

At the end of the upper substrate 1 facing this vertical connecting part 6, there is another vertical connecting part 7 connected to the vertical connecting part 6.
is formed, a part of which extends to the end of the upper substrate 1 to form a lower electrode terminal (hereinafter referred to as a lower plate terminal) 8.

The lower plate electrode 4 is electrically connected to the lower plate terminal 8 by interposing, for example, a conductive paste (not shown) between the upper and lower connecting portions 6 and 7.

Also, the distance between the upper substrate 1 and the lower substrate 2 is approximately 10 μm.
The width is maintained at a predetermined width, and its edges are sealed with a sealing material 9 made of frit glass, for example, and a nematic liquid crystal having optical rotation, for example, is sealed in this sealed space to display a liquid crystal display. The element is configured.

The liquid crystal display element configured in this manner has a structure in which each of the upper plate electrode 3 and the lower plate electrode 4 is used in combination with one input terminal, as shown in FIG. When using a Nesa film as an electrode, as the length of the electrode or its terminal becomes relatively long or the drive frequency increases, the effect of voltage drop due to the electrical resistance of the electrode or its terminal increases, and the voltage value applied to the liquid crystal increases. This changes depending on the location and driving frequency, resulting in uneven display conditions and reducing the operating margin due to time-division driving.

Therefore, an object of the present invention is to provide a liquid crystal display element that eliminates the above-mentioned drawbacks, provides a wide operating margin, and provides good display quality.

In order to achieve this object, the liquid crystal display device according to the present invention has electrode terminals configured so that input voltage is supplied from both ends of the electrodes.

The liquid crystal display element according to the present invention will be explained in detail below using the drawings.

FIG. 3 is an exploded view of essential parts showing an example of a liquid crystal display element according to the present invention, and since the same symbols as in FIGS. 1 and 2 represent the same elements, a description thereof will be omitted.

In the figure, the other end side of the lower plate electrode 4 formed on the lower plate substrate 2 is connected to the upper and lower connecting portion 1 formed at the end of the lower plate substrate 2.
0, and a vertical connection portion 11 is formed on the inner surface facing the upper substrate 10 that faces the upper and lower connection portions 10, a part of which extends to the end of the upper substrate 1 and is connected to the lower electrode. Terminal (
12 (hereinafter referred to as a lower plate terminal) is formed.

A conductive paste (not shown) is interposed between the upper and lower connecting portions 10.11 to electrically connect the lower substrate 2.
The upper lower plate electrode 4 is electrically connected to the lower plate terminal 12 on the upper substrate 1.

In the liquid crystal display element configured in this way, the same input voltage is supplied to the lower plate electrode 4 from both ends of the lower plate terminals 8 and 120, that is, from two points, and on the other hand, the same input voltage is supplied to the upper plate electrode 3 from the upper plate terminal 5. A voltage different from the input voltage is supplied, and a predetermined pattern is displayed by electro-optical changes in the liquid crystal (not shown) between the upper electrode 3 and the lower electrode 4.

In this case, in order to supply a predetermined voltage to the lower plate electrode 4, by supplying the same voltage from both ends (two points) of the lower plate terminal 8°120, the total resistance between both ends of the lower plate electrode 40 is reduced. When the input voltage is supplied to both ends of the lower plate terminals 8 and 120, the resistance R to the center of the lower plate electrode 4 where the resistance value is maximum is Ro/4, and the lower plate electrode 4 and its both ends are The electrical resistance on the line consisting of the lower plate terminals 8 and 12 is significantly reduced, the effect of voltage drop is reduced, and the voltage value applied to the liquid crystal changes less depending on the location and driving frequency, which improves the display state and operating margin. can eliminate the negative impact on

Here, the liquid crystal display element configured as described above will be explained in more detail as follows.

That is, the equivalent circuit of a conventional general liquid crystal display element is shown in FIG.

In the figure, Ro is the resistance (NESA resistance) of the Nesa film constituting the upper and lower electrodes, R is the pure resistance of the liquid crystal layer, C is the capacitance of the liquid crystal layer, and Z is the impedance of the liquid crystal layer. , Vo is the input voltage supplied between the upper plate terminal and the lower plate terminal, and vLc is the voltage applied to the liquid crystal.

In such an equivalent circuit, the impedance Z of the liquid crystal layer is RR Z ---(1-jωCR) 1+jωCR1-ωCR Also, the voltage vLo applied to the liquid crystal layer is V Lc--VO... 1) Ro+Z, and since ωCR>>1, Z--... (2) ωC.

And now, the pure resistance R of the liquid crystal layer is 109Ω, the capacitance C-l
0-11F1. When driving frequency f = IKHz, when there is no Nesa resistance Ro, the voltage applied to the liquid crystal layer is 100%.
, the relationship between Vtc/Vo and the Nesa resistance RO is as shown in FIG.

In addition, the pure resistance R of the liquid crystal layer is 109Ω, and the capacitance C-10-”
F, Nesa resistance When Ro=200 KO, the relationship between VLC/VO and drive frequency is as shown by characteristic ■ in FIG. 6, and Nesa resistance R.

In the case of −6O0KQ, the characteristic becomes as shown by the characteristic ■ in the figure.

In such a configuration, the sheet resistance of the Nesa film is usually 700 to 1 when fired at 400 to 500°C.
It is 400Ω/sq.

For example, in the case of a dot matrix of 80 characters (40/2 digits), the pattern width of the scanning (common) electrode is approximately 0.
．． 5 mm, pattern length approximately 200 mrrvfl
- Since it is necessary, the NESA resistance between both ends of the pattern is 280~
It becomes Ω at 560.

In the case of such an electrode, if input voltage is supplied to the lower plate electrode 4 only from the lower plate terminal 8 as shown in FIG. Almost 100% of the input voltage is applied between the plate electrodes 3, but
As can be seen from FIG. 5, a voltage of 98.3 to 96.6% of the input voltage is applied between the lower electrode 4 and the upper electrode 3 on the right side facing each other at a driving frequency f=IKHz.

The dot matrix element is usually 1/7 to 1/7
Since high time division driving with a duty of 16 is performed, the operating margin is approximately ±4 to 5%, which tends to cause display unevenness.

Furthermore, when the pattern width is reduced to 1/2, the effect is approximately 2
It will be doubled.

Therefore, if the input voltage is supplied from both ends of the lower plate electrode 40 as described above, the Nesa resistance will be the maximum at the lower plate electrode 40.
The resistance between both ends of the pattern is 1/4 at the center of the pattern, and the interelectrode voltage between the upper plate electrode 3 and the lower plate electrode 4 at that part is 99.7 to 99.1% of the input voltage.

Therefore, the two-point input effect to the lower plate terminal 8°12 is obvious.

Here, as a means to obtain the same effect as above, it is possible to make the pattern width four times that of the conventional method, or to make the thickness of the Nesa film four times as much as before.

The former has drawbacks such as a larger dot pattern and the latter lowers the transmittance, which is not preferred.

Next, since the dot matrix performs high time division driving, one drive frequency is 320 when the duty is 1/16.
~1280Hz.

In this case, with Nesa resistance Ro=200KQ, V t, c
/ 1.2% for Vo, VLC/V for Ro=600KQ
A difference of 3.4% occurs in O, which greatly affects the operating margin.

Of course, the influence of this driving frequency also affects the
In other words, by inputting two points, it is possible to significantly reduce the number of inputs.

In the above embodiments, the present application has been described only in the case where it is applied to the lower plate electrode, but the present invention is not limited to this. When applied, the same effects as described above can be obtained.

As explained above, in the liquid crystal display element according to the present invention, input to the electrodes is performed from the terminals (two points) of the electrodes. The extremely excellent effect of reducing the voltage drop due to the increase in resistance, improving display quality, and expanding the operating margin can be obtained.

[Brief explanation of drawings]

1 and 2 are perspective views and exploded views of essential parts showing an example of a conventional liquid crystal display element, FIG. 3 is an exploded view of essential parts showing an example of a liquid crystal display element according to the present invention, and FIG. A diagram showing an equivalent circuit of a liquid crystal display element, FIG. 5 shows vLc/v with respect to Nesa resistance
FIG. 6 is a characteristic diagram showing the relationship between vLc/vo and one drive frequency. 1... Upper board, 2... Lower board, 3
...Top plate electrode, 4...Bottom plate electrode, 5.
...Top plate electrode terminal (upper plate terminal), 6,7...
...Upper and lower connection part, 8...Lower plate electrode terminal (lower plate terminal), io, 1i...Upper and lower connection part, 12...
...Lower plate electrode terminal (lower plate terminal).

Claims (1)

[Claims] 1 An insulating upper substrate and a lower substrate arranged to face each other, an upper electrode and a lower electrode formed respectively on the opposing surfaces of the two substrates, and a liquid crystal sealed between the two electrodes. 1. A liquid crystal display element comprising at least one of the above electrodes, wherein the resistance value of the electrode itself is substantially reduced by supplying at least one input of the electrode from both ends of the electrode.