1. Field of the Invention
Aspects of the present invention relate to a sealing apparatus and a method of manufacturing a flat display device using the sealing apparatus.
2. Description of the Related Art
Display devices are increasingly being replaced by slim, portable flat panel display devices. Electroluminescent display devices, among the flat panel display devices, are self luminescent display devices, and have advantages of a wide angle of view, a high contrast level, and a fast response speed. Therefore, the electroluminescent display devices are being pursued as a display device of the next generation.
Organic light-emitting display devices having a light-emitting layer composed of an organic material have characteristics of brightness, a lower driving voltage, and a higher response speed and are capable of displaying more colors than inorganic light-emitting display devices. Generally, an organic light-emitting display device has a structure in which at least one organic layer including an emission layer is interposed between a pair of electrodes (that is, a first electrode and a second electrode). The first electrode is formed on a substrate, and functions as an anode that injects holes. An organic layer is formed on the first electrode. The second electrode functions as a cathode that injects electrons, and is formed on the organic layer so as to face the first electrode.
When moisture or oxygen flows into elements of such an organic light-emitting display device from the surroundings, there are problems due to oxidation of an electrode material. Examples of such problems are exfoliation of an electrode surface or the like. These problems shorten the life of the elements, lower a light-emitting efficiency, and deteriorate emitted light colors. Therefore, in the manufacture of the organic light-emitting display device, a sealing process is usually performed so that the elements can be isolated from outside exposure and moisture infiltration into the elements. In the sealing process, usually a polymer organic material (such as polyethylene terephthalate (PET)) that is a thermoplastic polyester, is laminated on the second electrode or a cover or a cap is formed on the second electrode. Nitrogen gas is filled in the cover or the cap, and the rim of the cover or the cap is capsule-sealed by a sealant such as epoxy. The cover or the cap may be made of a metallic material or a glass material that is moisture absorbent.
However, such methods can allow for some element damaging materials such as moisture, oxygen, or the like to infiltrate into the device from the outside. In addition, the methods are not well suited when applied to top-emitted organic light-emitting display device having elements that are specifically weak to moisture, and a process to realize the methods is complicated. In order to solve the above mentioned problems, a capsule sealing method is used to enhance adhesion between an element substrate and a cap using a frit as a sealant.
The method of capsule-sealing an organic light-emitting display device includes coating a frit on a glass substrate which perfectly seals the element substrate and the cap together. Thus, the organic light-emitting display device can be protected from being infiltrated with the element damaging material more effectively than an organic light-emitting display device using epoxy as a sealant.
In the method of capsule-sealing the organic light-emitting display device with the frit, after the frit is coated on each sealing portion of the organic light-emitting display device, a laser irradiating apparatus is moved to the sealing portions thereof and irradiates a laser beam to the sealing portions to harden the frit for sealing.