US20080007686A1

US20080007686A1 - Liquid crystal panel with sealant having conductive beads mixed therein and method for fabricating same

Info

Publication number: US20080007686A1
Application number: US11/825,936
Authority: US
Inventors: Chi-Jung Chen; Kun-Hsing Hsiao; Jia-Yi Wu
Original assignee: Innolux Display Corp
Current assignee: Innolux Corp
Priority date: 2006-07-07
Filing date: 2007-07-09
Publication date: 2008-01-10
Also published as: US20080007972A1; US7575361B2; TWI342445B; TW200804928A

Abstract

An exemplary liquid crystal panel (2) includes a first substrate (21), a second substrate (23) opposite to the first substrate, a liquid crystal layer (25) sandwiched between the first and second substrates, and a sealant (27) provided at the first substrate and attaching the first and second substrates together. The sealant has a plurality of conductive beads (270) mixed therein. The conductive beads electrically interconnect the first and second substrates. Because the conductive beads are mixed in the sealant, the conductive beads do not influence a uniformity of a height of the sealant. Therefore, the liquid crystal panel can provide a good quality display. Furthermore, the process of mixing the conductive beads in the sealant is simpler than a conventional process of applying conductive beads onto an outside of a sealant. Thus, the method for fabricating the liquid crystal panel is simplified.

Description

FIELD OF THE INVENTION

The present invention relates to liquid crystal panels and methods for fabricating these panels; and particularly to a liquid crystal panel including a sealant having conductive beads mixed therein, and a method for fabricating such liquid crystal panel.

GENERAL BACKGROUND

A liquid crystal display (LCD) is capable of displaying a clear and sharp image through thousands or even millions of pixels that make up the complete image. The liquid crystal display has thus been applied to various electronic equipment in which messages or pictures need to be displayed, such as mobile phones and notebook computers. The liquid crystal display generally includes a liquid crystal panel for displaying images, and a backlight for illuminating the liquid crystal panel.
Referring to FIG. 5, a typical liquid crystal panel 1 includes a thin film transistor (TFT) substrate 11, a color filter (CF) substrate 13 opposite to the TFT substrate 11, a liquid crystal layer 15 sandwiched between the two substrates 11, 13, conductive adhesive 16, and a sealant 17.
The sealant 17 is applied at a periphery of the TFT substrate 1, and is sandwiched between the two substrates 11, 13. The two substrates 11, 13 and the sealant 17 cooperatively define a space for accommodating the liquid crystal layer 15. The conductive adhesive 16 is applied at an outside of the sealant 17, and electrically connects the two substrates 11, 13. The conductive adhesive 16 is generally applied in the form of discrete beads. The beads include at least one silver-based compound, which includes silver ions. The silver-based compound can for example be silver nitrate (AgNO₃).
A method of fabricating the liquid crystal panel 1 generally includes: applying the sealant 17 at a periphery of the TFT substrate 11, thereby defining a space; distributing spacers (not shown) on the TFT substrate 11, and filling liquid crystal material in the space; applying the conductive adhesive 16 to the outside of the sealant 17; and in a vacuum environment, attaching the CF substrate 13 onto the TFT substrate 11 to form the liquid crystal panel 1.
In the process of fabricating the liquid crystal panel 1, a height of the sealant 17 is a factor that can influence the quality of the display provided by the liquid crystal panel 1 in use. In particular, when the sealant 17 has a uniform height, this helps ensure the liquid crystal material has a uniform thickness between the two substrates 11, 13. In turn, the liquid crystal material is able to uniformly and accurately generate images. However, because the conductive adhesive 16 is applied at the outside of the sealant 17, the uniformity of the height of the sealant 17 may be diminished. Thereby, the display quality of the liquid crystal panel 1 may be impaired.
One way to overcome the above-described problems is to reduce the sizes of the beads of the conductive adhesive 16. If this is done, a proportion of the silver-based compound mixed in the conductive adhesive 16 needs to be increased, in order to maintain good electrical conductivity of the conductive adhesive 16. However, in general, it is difficult to properly mix a high proportion of the silver-based compound in the conductive adhesive 16. Furthermore, when the conductive adhesive 16 has a high proportion of silver-based compound, the step of applying the conductive adhesive 16 on the TFT substrate 11 can be problematic.
Therefore, a new liquid crystal panel that can overcome the above-described problems is desired. A method for fabricating such a liquid crystal panel is also desired.

SUMMARY

In one preferred embodiment, a liquid crystal panel includes a first substrate, a second substrate opposite to the first substrate, a liquid crystal layer sandwiched between the first and second substrates, and a sealant provided at the first mother substrate and attaching the first and second substrates together. The sealant has a plurality of conductive beads mixed therein. The conductive beads electrically interconnect the first substrate and the second substrate.
In another preferred embodiment, a method for fabricating a liquid crystal panel includes: providing a first substrate; mixing a plurality of conductive beads into a sealant; applying the sealant having the plurality of conductive beads at a periphery of the first substrate, thereby defining an accommodating space; dropping liquid crystal material into the accommodating space, thereby forming a liquid crystal layer; providing a second substrate, and attaching the second substrate onto the first substrate such that at least a plurality of the plurality of conductive beads in the sealant electrically interconnect the first and second substrates; and curing the sealant.
Other novel features and advantages will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, all the views are schematic.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded, isometric, abbreviated view of a liquid crystal panel according to a first embodiment of the present invention, the liquid crystal panel including a sealant (partly cut away), the sealant including a plurality of conductive beads.

FIG. 2 is an enlarged, isometric view of one of the conductive beads of FIG. 1, with part of the conductive bead cut out.

FIG. 3 is a flowchart summarizing an exemplary method for fabricating the liquid crystal panel of FIG. 1.

FIG. 4 is an isometric view of one of conductive beads of a liquid crystal panel according to a second embodiment of the present invention, with part of the conductive bead cut out.

FIG. 5 is an exploded, isometric view of a conventional liquid crystal panel.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIG. 1, a liquid crystal panel 2 according to a first embodiment of the present invention is shown. The liquid crystal panel 2 includes a first substrate 21, a second substrate 23 opposite to the first substrate 21, a liquid crystal layer 25 sandwiched between the first and second substrates 21, 23, and a sealant 27.
The first substrate 21 is a thin film transistor (TFT) substrate, and includes a plurality of pixel electrodes 211 and a plurality of common electrodes 213. The second substrate 23 is a color filter (CF) substrate, and includes a transparent conductive layer 231. The sealant 27 is applied at a periphery of the first substrate 21, and is sandwiched between the first and second substrates 21, 23. The two substrates 21, 23 together with the sealant 27 cooperatively define a space therebetween, for accommodating the liquid crystal layer 25. The sealant 27 can be ultraviolet-curable sealant or heat-curable sealant or a combination of these, and includes a plurality of generally spherical conductive beads 270 mixed therein.
Referring also to FIG. 2, each of the conductive beads 270 includes a core 271, and a conductive layer 272 substantially covering a surface of the core 271. The core 271 is generally made from silicate, but can be made from other material such as fiberglass. The conductive layer 272 is made from at least one material selected from the group consisting of silver, tin, lead, gold, copper, nickel, and aluminum; and is formed by an electroplating method or a coating method.
The conductive beads 270 mixed in the sealant 27 can electrically connect the common electrode 213 of the first substrate 21 with the transparent conductive layer 231 of the second substrate 23. Good electrical conductivity can be achieved by configuring a distribution density of the conductive beads 270 appropriately. Preferably, a proportion by weight of the conductive beads 270 relative to the sealant 27 is in the range from 0.5%˜5%. For example, the proportion by weight of the conductive beads 270 relative to the sealant 27 can be 1%.
Referring to FIG. 3, a method for fabricating the liquid crystal panel 2 includes: step S1, providing the first substrate 21 and forming the sealant 27 having the conductive beads 270 mixed therein; step S2, forming the liquid crystal layer 25; step S3, providing the second substrate 23 and attaching the first and second substrates 21, 23 together; and step S4, curing the sealant 27.
In step S1, the first substrate 21 is provided. The conductive beads 270 are mixed into the sealant 27. The sealant 27 having the conductive beads 270 is applied at a periphery of the first substrate 21 by a printing method or a coating method. Thereby, an accommodating space for receiving the liquid crystal layer 25 is defined. The accommodating space has a top opening.
In step S2, the liquid crystal layer 25 is formed. A plurality of spacers (not shown) are distributed in the accommodating space. Liquid crystal material (not shown) is then dropped into the accommodating space.
In step S3, the second substrate 23 is provided, and the first and second substrates 21, 23 are attached together. The second substrate 23 is first loosely attached onto the first substrate 21, and is then pressed. Thereby, the common electrode 213 of the first substrate 21 is electrically connected with the transparent conductive layer 231 of the second substrate 23 via the conductive beads 270 that are mixed in the sealant 27.
In step S4, the sealant 270 is cured, thereby forming the liquid crystal panel 2.
In summary, because the conductive beads 270 are mixed in the sealant 27, the conductive beads 270 do not influence a uniformity of a height of the sealant 27. Therefore, the liquid crystal panel 2 can provide a good quality display. Furthermore, the process of mixing the conductive beads 270 in the sealant 27 is simpler than a conventional process of applying conductive beads onto an outside of a sealant. Thus, the method for fabricating the liquid crystal panel 2 is simplified, and the liquid crystal panel 2 can have a reduced cost.
Referring to FIG. 4, a conductive bead 370 of a liquid crystal panel according to a second embodiment of the present invention is similar to the conductive bead 270 of the first embodiment. However, the conductive bead 370 includes a generally cylindrical core 371, and a conductive layer 372 substantially covering a surface of the core 371. The core 371 is generally made from fiberglass, but can be made from other material such as silicate. The conductive layer 372 is made from at least one material selected from the group consisting of silver, tin, lead, gold, copper, nickel, and aluminum; and is formed by an electroplating method or a coating method.
It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.

Claims

1. A liquid crystal panel comprising:

a first substrate;

a second substrate opposite to the first substrate;

a liquid crystal layer sandwiched between the first and second substrates; and

a sealant provided at the first substrate and attaching the first and second substrates together, the sealant having a plurality of conductive beads mixed therein, the conductive beads electrically interconnecting the first substrate and the second substrate.

2. The liquid crystal panel as claimed in claim 1, wherein the sealant comprises at least one of ultraviolet-curable sealant and heat-curable sealant.

3. The liquid crystal panel as claimed in claim 1, wherein each of the conductive beads comprises a core and a conductive layer substantially covering a surface of the core.

4. The liquid crystal panel as claimed in claim 3, wherein the core is made from silicate or fiberglass.

5. The liquid crystal panel as claimed in claim 3, wherein the core is generally spherical or generally cylindrical.

6. The liquid crystal panel as claimed in claim 3, wherein the conductive layer is made from at least one material selected from the group consisting of silver, tin, lead, gold, copper, nickel, and aluminum.

7. The liquid crystal panel as claimed in claim 1, wherein a proportion by weight of the conductive beads relative to the sealant is in the range from 0.5%˜5%.

8. The liquid crystal panel as claimed in claim 7, wherein the proportion by weight of the conductive beads relative to the sealant is equal to 1%.

9. The liquid crystal panel as claimed in claim 1, wherein the first substrate is a thin film transistor (TFT) substrate, and comprises a plurality of pixel electrodes and a plurality of common electrodes.

10. The liquid crystal panel as claimed in claim 9, wherein the second substrate is a color filter (CF) substrate, and comprises a transparent conductive layer.

11. The liquid crystal panel as claimed in claim 10, wherein the conductive beads electrically interconnect the common electrodes of the first substrate and the transparent conductive layer of the second substrate.

12. A method for fabricating a liquid crystal panel, the method comprising:

providing a first substrate;

mixing a plurality of conductive beads into a sealant;

applying the sealant having the plurality of conductive beads at a periphery of the first substrate, thereby defining an accommodating space;

dropping liquid crystal material into the accommodating space, thereby forming a liquid crystal layer;

providing a second substrate, and attaching the second substrate onto the first substrate such that at least a plurality of the plurality of conductive beads in the sealant electrically interconnect the first and second substrates; and

curing the sealant.

13. The method as claimed in claim 12, wherein the sealant is applied at the first substrate by a coating method.

14. The method as claimed in claim 12, wherein the sealant is applied at the first substrate by a printing method.

15. The method as claimed in claim 12, further comprising distributing spacers in the accommodating space after the accommodating space is defined.

16. A liquid crystal panel comprising:

a first substrate;

a second substrate opposite to the first substrate;

a liquid crystal layer sandwiched between the first and second substrates; and

a sealant provided at the first substrate and attaching the first and second substrates together, the sealant containing conductive material thereof to electrically interconnect the first substrate and the second substrate.