JPS602570Y2 - lcd display panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal display panel in which thin film field effect transistors are stacked to enable multiplex driving.

It is well known that display panels that utilize the electro-optic effect of liquid crystals are widely used as display elements for digital watch calculators and the like.

However, liquid crystal display panels are not good at multiplex driving because their response characteristics are slow and the gradient of their dark value characteristics is gentle.

In the currently widely used FE-TN type liquid crystal display panel, the number of scanning lines in multiplex driving is about a few lines due to crosstalk problems and contrast issues.

In addition, recently, liquid crystal display panels that use a liquid crystal material made by adding dye to cholesteric liquid crystal and display color by utilizing the cholesteric-nematic phase transition effect have a wider field of view and a wider display area than FE-TN type liquid crystal display panels. The screen is bright and the color can be changed by selecting the dye (rich in fashion), so it is thought that it will have a wide range of applications, but unfortunately, multiplex drive is difficult.

Enables multiplex drive of liquid crystal display panels.
Alternatively, in order to increase the number of scans in multiplex drive, it has been proposed to laminate a switching element or a nonlinear element on one electrode substrate of a liquid crystal display panel.

The ZnO varistor, Sj
Or MOS-FET formed on SOS wafer substrate
, II-VI compound semiconductor thin film field effect transistor, amorphous Si (hereinafter referred to as 21-
There is a thin film field effect transistor (abbreviated as 3i).

Among these switching elements, thin film field effect transistors using If-VI compound semiconductors or a-3i can be easily made into large area because thin films can be formed on glass substrates using techniques such as sputtering. Therefore, if a metal mask is used, it is also possible to stack thin film transistors on a portion of a glass substrate.

Furthermore, since it is a thin film, material costs are low and mass production is possible, so it is advantageous in terms of cost.

However, because thin film field effect transistors are thin films, they are easily affected by the surrounding environment, and their switching characteristics deteriorate over time, particularly in adverse environments where moisture is present.

Generally, thin film field effect transistors are molded with resin or the like to prevent deterioration over time.

However, when assembling a liquid crystal display panel, steps of resin coating and resin baking are required for molding the thin film field effect transistor.

When molding a thin film field effect transistor before bonding a pair of electrode substrates that make up a liquid crystal display panel,
There is a drawback that the space factor (display area/outer area) becomes smaller due to spread of resin etc. after application, and when molding a thin film field effect transistor after bonding a pair of electrode substrates, it is difficult to bond the electrode substrates together. Therefore, two heating steps are required when firing the resin used in the mold, which has a negative effect on the thin film field transistor.

An object of the present invention is to provide a liquid crystal display panel having a structure in which the thin film field effect transistor is molded at the time of bonding the electrode substrate to prevent deterioration of the thin film field effect transistor.

According to the present invention, in a liquid crystal display panel in which an electrode substrate A on which thin film field effect transistors are laminated and another electrode substrate B are sealed with a sealant, and a liquid crystal material is filled in the gap between the electrode substrates A and B, the sealant is attached to the thin film A liquid crystal display panel characterized in that it has a structure that also serves as a mold for a field effect transistor is obtained.

The present invention will be explained in detail below using examples.

FIG. 1 shows the structure of the a-5i thin film field effect transistor used in the example, and FIG. 1(I) is a plan view;
FIG. 1 (II) is a front view.

On a glass substrate (Corning 7059) 4, an AI electrode is attached as a gate electrode 1 in a strip shape (width 100 μm).

Next, silane gas (
The mixed residue of SiH4) and ammonia gas (NH3) is
f glow discharge to form a silicon nitride (Si3H1) film (
A film thickness of 0.7 μm) 5 is formed.

Subsequently, SiH4 gas is caused to glow discharge using the same CVD method to form an a-3i film (thickness: 1 μm) 6.

Next, AI electrodes (width 100 μm) are attached as the drain electrode 2 and source electrode 3.

In this example, the distance 1 (channel length) between the drain electrode and the source electrode is 40 μm.

The gate electrode and drain electrode are connected to an external drive circuit, and the source electrode is connected to an internal segment electrode.

FIG. 2(I) shows an a-3i film field effect transistor 7.
This is a schematic perspective view showing the arrangement and wiring of the segment electrodes 8. The drain electrodes are commonly connected for each digit,
Gate electrodes corresponding to the same segment of each digit are commonly connected, and source electrodes are connected to each segment.

FIG. 2(n) is a direct view of the common electrode pattern.

Multiplex drive will be explained using FIG. 2.

The gate electrodes Ga to Gg are scanned one by one by line sequential scanning.

Gate voltage ■ during scanning. When V = 15V is applied, the thin film field effect transistor is turned on, and charges are charged between the segment electrode and the common electrode by the drain electrode Vp applied to the drain electrode.

Specifically, in synchronization with each scan of Ga-Gg, V = 15V is applied to the drain electrodes D1D2... in the case of a selected segment, and V = 15V is applied in the case of a non-selected segment. o ” Apply Qv.

The common electrode com is at ground potential.

When scanning is completed up to Gg, return to Ga, but apply a drain voltage of opposite polarity to the previous frame, that is, in the case of a selected segment, V o "-15V, and in the case of a non-selected segment, V o = Ov Apply.

This is done to make the voltage Vt applied between the segment electrodes and the common electrode an alternating voltage.

(2) During scanning, the thin film field effect transistor is turned on, and charges are charged to Vt, =Vo, but after scanning, the thin film field effect transistor is turned off (VC = 0), and the charged charges are Discharged.

However, the off resistance Roff of the thin film field effect transistor
The ratio of on resistance Ron is more than 300 times, and the charge discharge time is also longer than the charge discharge visit, which is more than 30@, so even after scanning, the voltage of L is maintained until the next scanning. dripping

With the above driving method, the selected segment has a peak value of 15
An AC rectangular wave of V frequency 1/2T (T is frame time) is applied, and no voltage is applied to non-selected segments.

The liquid crystal display panel of the example will be described below with reference to FIG.

FIG. 3(I) shows a front sectional view, and FIG. 3(II) shows a side view.

The segment electrodes and a-3i thin film field effect transistors shown in FIG. 2(I) are formed on the electrode substrate 10,
On the other hand, the common electrode shown in FIG. 2 (II) is formed on the electrode substrate 11.

A-5i thin film field effect transistors 13 are formed on the electrode substrate 10 in the arrangement shown in FIG. 3(I).

An epoxy adhesive (for example, adhesive H77 manufactured by Epotek Co., Ltd.) is applied to the electrode substrate 11 on which the vertical alignment treatment film has been applied at 1 in the figure.
Print and coat in the shape shown in 2.

Next, the electrode substrates 10 on which the vertical alignment treatment film has been applied are stacked one on top of the other while aligning the electrode patterns, and then burned at 120° C. for 1 hour while applying a load.

Both electrode substrates are kept at a constant distance by particles (15 μm in diameter) contained in the epoxy adhesive.

As shown in the figure, a-3i thin film field effect transistor 13
is molded with epoxy adhesive.

Next, the liquid crystal material 14 is filled into the panel through the injection port 16 in a low vacuum (10-'' to 10-' mmHg).

The liquid crystal material is a mixture of biphenyl-based nematic liquid crystal E7 (manufactured by BDH) with positive dielectric anisotropy and cholesteryl chloride at a ratio of 9:1 (cholesteric liquid crystal in nature), and dichroic dye GB. -3 (manufactured by Blue Nippon Kanko Shiki Co., Ltd.) was added in an amount of 1%.

After filling the liquid crystal material, the injection port is temporarily sealed with Aron Alpha (manufactured by Toa Gohikagaku Co., Ltd.), and then permanently sealed with a silicone adhesive 15.

The liquid crystal display panel of the example is manufactured through the above steps.

In this liquid crystal display panel, the selected segment to which the 15V AC rectangular wave is applied is decolored, so that the selected segment is displayed as white characters with a blue background.

As is clear from the above, in the liquid crystal display of the present invention, the layered A-3I thin film field effect transistor is bonded to a moisture-resistant and heat-resistant adhesive that has been developed for the liquid crystal display panel. Since the A-8I thin film field effect transistor is molded with a thin film material and isolated from the outside air and the liquid crystal material, the switching characteristics of the A-8I thin film field effect transistor have little change over time and are highly reliable.

Another advantage is that there is no need for a process for molding the thin film field effect transistor.

The present invention has been described above with reference to examples. In the examples, a 3-3i thin film field effect transistor was used, but an n-
It is also effective in the case of VI compound semiconductor (eg Cd5e) thin film field effect transistors.

In addition, in the embodiment, a liquid crystal display panel was described that uses a liquid crystal material in which a dye is added to cholesteric liquid crystal and performs color display by utilizing the cholesteric liquid crystal phase transition effect. All liquid crystal display channels using effects, such as liquid crystal FE-TN
The present invention is also effective in liquid crystal display panels that utilize this effect.

Furthermore, the epoxy adhesive H77 used in the examples is merely an example, and the present invention is not intended to limit the sealing material.

Furthermore, although the present embodiment has been described with respect to segment numeric display, the present invention is also effective for other displays.

Further, the position on the electrode substrate of the a-3i thin film field effect transistor is not limited to that explained in the embodiment,
The printing screen of the sealant is designed so that the sealant molds the A-3I thin film field effect transistor when the pair of electrode substrates are bonded together, and the A-3I thin film field effect transistor is positioned outside the display window. Good to have.

[Brief explanation of the drawing]

FIG. 1 schematically shows the structure of a thin film field effect transistor laminated on an electrode substrate, and FIG. FIG. 3, which shows a wiring diagram, schematically shows the structure of a liquid crystal display panel according to an embodiment of the present invention. 1 is a gate electrode, 2 is a drain electrode, 3 is a source electrode,
4 is an electrode substrate, 5 is an insulating film (Si3N, film), 6 is a-
3i film, 7 is an a-3i thin film field effect transistor, 8 is a segment electrode, 9 is a common electrode, 10.11 is an electrode substrate, 12 is a sealing material, 13 is an a-3i thin film, 14 is a liquid crystal,
15 is a sealing material, and 16 is an injection hole.

Claims (1)

[Scope of utility model registration request] In a liquid crystal display panel in which an electrode substrate A on which thin film field effect transistors are laminated and another electrode substrate B are sealed with a sealing material, and a liquid crystal material is filled in the gap between the electrode substrates A and B, the sealing material is a layer of the thin film field effect transistors. A liquid crystal display panel characterized by a structure that also functions as a mold.