Flexible display and method for forming alignment key of the same

Abstract

A flexible display and method for forming alignment key of the same are disclosed, which includes an alignment key required to align positions between film layers, the flexible display comprising a substrate defined display area and non-display area and an alignment key forming part including an alignment key and transmission part at the circumference of the alignment key, wherein the alignment key forming part is formed at the non-display area of the substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention.

In the drawings:

FIGS. 1A and 1B are illustrating photographs of a related art flexible display;

FIG. 2 is a cross section view for aligning the glass substrate in related art;

FIG. 3 is an enlarged view long ‘A’ region of FIG. 2;

FIG. 4 is an illustrated figure in the process of observing ‘A’ region of FIG. 3 using a vision camera;

FIG. 5 is a cross section view of a flexible display and a method for aligning positions of the same according to an embodiment;

FIG. 6 is an enlarged view long ‘B’ region of FIG. 5;

FIG. 7 is an illustrated figure in the process of observing ‘B’ region of FIG. 5 using a vision camera;

FIG. 8A˜8D are cross section views illustrating a method for forming an alignment key of the flexible display according to the embodiment;

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

Hereinafter, a flexible display according to the present invention will be described with reference to the accompanying drawings.

FIG. 5 is a cross section view of a flexible display and a method for aligning positions of the same according to an embodiment, FIG. 6 is an enlarged view long ‘B’ region of FIG. 5, and FIG. 7 is an illustrated figure in the process of observing ‘B’ region of FIG. 6 using a vision camera.

As shown in FIGS. 5 to 7, the flexible display according to the embodiment, includes, the substrate 300 and an alignment key forming part formed 305 on the edge of the substrate 300, wherein the alignment key forming part 305 has an alignment key 311 and a transmission part 312. The transmission part 312 is formed to oxidize the region excluding the region corresponding to the alignment key 311 in the alignment key forming part 305.

A shadow mask 100 is disposed under the flexible display substrate 300, a mask hole 105 of the shadow mask 100 is formed in the region corresponding to the alignment key 311 and a vision camera 200 is disposed above the flexible display substrate 300.

Once the observation part of vision camera 400 is detected and the alignment key 311 of the flexible display substrate 300 is read using the vision camera 200, the mask hole 105 corresponding to the shadow mask 100 is found so as to align the shadow mask 100 and the flexible display substrate 300.

Next, source of an organic emitting material is disposed under the shadow mask 100 and then an organic emitting layer is formed to transmit (permeate) the pattern of the shadow mask 100 on the flexible display substrate 300.

Here, a normal metal 301 is formed on the region excluding the alignment key forming part 305 without additional oxidation treatment. The alignment key forming part 305 is formed on the predetermined part of non-display region on the flexible display substrate, wherein the non-display region is not displayed region.

FIGS. 8A˜8D are plan views and cross section views illustrating a method for forming an alignment key of the flexible display according to the embodiment.

First, a photo resist layer 351 is formed on the flexible display substrate 350. As show FIG. 8A, the photo resist layer 351 is formed in the shape of covering the upper side, the lower side and the lateral side together. The reason why the photo resist layer 351 has this shape is to protect the substrate and to prevent damage excluding the transmission part (312 in FIG. 8D) while the flexible display substrate 350 is dipped (soaked) in an oxidization solution, to oxidize the transmission part corresponding to the circumference of the alignment key (311 in FIG. 8D).

Here, the flexible display substrate 350, in example, is made of Al or SUS (Stainless Use Steel) series or reflective metal. And, the thickness of the flexible display substrate 350 is about 10 μm˜9 mm (9000 μm).

The photo resist is made of at least one of acryl series, e.g. Novolak series etc., the photo resist may be positive or negative photo-sensitivity. In this case, an image of the mask required to pattern the photo resist layer is determined based on the photo-sensitivity of the photo resist.

As shown in FIG. 8b, the photo resist 351 is selectively exposed and developed, so that a photo resist pattern 351a is formed to open a predetermined part. The non-display area of the flexible display substrate 350 has an alignment key forming part at the edge of the flexible display substrate 350. The photo resist pattern 351a is formed by selectively removing the photo resist layer 351 to expose and develop the portion corresponding to the alignment key forming part (305 in FIG. 8D) except a center part of the alignment key forming part.

Next, the photo resist pattern 351a is baked to be stable without its deforming in the next process.

As shown in FIG. 8C, the flexible display substrate 380 including the photo resist pattern 351a is dipped in the bath 500 filled with an oxidation solution and an electrode 502 is dipped in other part of the oxidation solution, and then a current is flowed through a galvanometer between the flexible display substrate 380 and the electrode 502, induced oxidation-reduction reaction between the opened alignment key forming part 305 of flexible display substrate 380 and the electrode.

Through this oxidation-reduction reaction the exposed part of the flexible display substrate 350 is oxidized, in example, in this case, the flexible display substrate 350 is made of Al material, the oxidized part is denaturalized to Al2O3. As shown in FIG. 8D, the oxidized part is shown to be transparent, therefore it is used as a transmission part 312. In the alignment key forming part, the masked part with the photo resist pattern 351a is remained as it is, the masked part of the alignment key forming part is used as an alignment key 311 after the process of observation using a vision camera.

The transmission part 312 is oxidized corresponding to the thickness of the flexible display substrate 300. Unless the transmission part 312 is oxidized less than the thickness of the flexible display substrate 300, oxidation should be accomplished for the alignment key forming part up to the state to be shown through the vision camera.

The method as stated above is an electrochemical method, in this case the oxidation solution 501 is made of oxalic acid, phosphoric acid, sulfuric acid or mixed solution including the former.

And as shown in FIG. 8D, the removing of photo resist pattern 351a is processed with dipping in a stripper solution to strip the photo resist material selectively.

Beside the electrochemical method, there is an electro-polishing method as method of forming an alignment key in the shape of the transmission part. The electro-polishing method is a method to decrease thickness of a predetermined. In this case, after the electro-polishing, the observation of the degree of alignment is performed with observing the step difference between decreased part and non-decreased part using a vision camera. And it is possible to align between shadow mask and flexible display substrate with the observation.

The electro-polishing method is alternate with the electrochemical method or carried out with electrochemical method together.

Also, beside the electrochemical method or electro-polishing, it is possible to form an epoxy series material on the region corresponding to the transmission part, to be shown transparent.

Also, the shape of the alignment key 311 in FIG. 7 may be changeable as a circle or polygon including a triangle or rectangular or star shape.

The flexible display substrate including alignment key according to the present invention, is formed through a treatment on the flexible display substrate and the flexible display substrate including alignment key can align between evaporated or deposited forming layer and shadow mask including pattern to deposit or evaporate.

As mentioned above, the flexible display according to the present invention has the following advantages.

First, the flexible display substrate is made of opaque metal, in the related art, the vision camera above the rear surface cannot observe position of alignment, so that an extra apparatus to align is needed. In the present invention, the flexible display substrate has an alignment key in itself defined of oxidation, so that the alignment key can align between evaporated or deposited forming layer on the flexible display substrate and shadow mask including pattern to deposit or evaporate without extra outer alignment apparatus.

Secondly, due to that there is an alignment key in the flexible display substrate, so that in the process of forming organic emitting layer or other forming layer, it is possible to simplify apparatus required while the alignment process.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims

1. A flexible display comprising: a substrate defined display area and non-display area; andan alignment key forming part including an alignment key and transmission part at the circumference of the alignment key, wherein the alignment key forming part is formed at the non-display area of the substrate.

2. The flexible display of claim 1, wherein the substrate is made of metal and the substrate in the transmission part is oxidized to be a metal oxide.

3. The flexible display of claim 1, wherein the transmission part is formed having a thickness substantially less than that of the alignment key by electro-polishing.

4. The flexible display of claim 1, further comprising an epoxy material on the transmission part.

5. The flexible display of claim 1, wherein the alignment key has a substantially circular or polygonal shape.

6. The flexible display of claim 1, wherein the substrate, excluding the transmission part, is formed of an opaque metal.

7. The flexible display of claim 6, wherein the substrate is made of at least one of Al, SUS series (Stainless Use Steel) and an alloy including Al and SUS series.

8. The flexible display of claim 1, wherein the substrate has a thickness of about 10 μm to about 9 mm (9000 μm).

9. A method for forming an alignment key flexible display comprising: coating a photo resist layer on a substrate defined display area and non-display area, wherein the non-display area has an alignment key forming part;forming a photo resist pattern by selectively removing the photo resist layer to expose and develop a portion corresponding to the alignment key forming part except a center part of the alignment key forming part; andforming an alignment key in the center part inside the alignment key forming part and a substantially transparent transmission part at the circumference of the alignment key.

10. The method of claim 9, further comprising a step of baking the photo resist pattern after the step of forming the photo resist pattern.

11. The method for claim 9, wherein the step of forming the alignment key and transmission part includes: dipping the substrate at one side and an electrode at the other side, respectively, in a bath filled with an oxidation solution; andinducing an oxidation-reduction reaction between the alignment key forming part of the substrate and the electrode and oxidizing the transmission part by using the photo resist pattern as a mask.

12. The method of claim 11, wherein the oxidation solution is made of at least one of oxalic acid, phosphoric acid, sulfuric acid and a mixed solution including formers.

13. The method of claim 12, further comprising a step of removing the photo resist pattern by using a stripper.

14. The method of claim 9, wherein the step of forming the alignment key and transmission part includes: electro-polishing the alignment key forming part of the substrate by using the photo resist pattern as a mask.

15. The method of claim 9, wherein the step of forming the alignment key and transmission part includes: coating an epoxy material on the alignment key forming part by using the photo resist pattern as a mask.

16. The method of claim 9, wherein the substrate is made of at least one of Al, SUS series and an alloy including Al or SUS series.

17. The method of claim 9, wherein the substrate has a thickness of about 10 μm to about 9 mm (9000 μm).