Local seal for encapsulation of electro-optical element on a flexible substrate
An electroluminescent display or lighting product incorporates a panel comprising a collection of distinct light-emitting elements formed on a substrate. A plurality of distinct local seals are formed over respective individual light-emitting elements or groups of light-emitting elements. Each local seal is formed by depositing a low melting temperature glass powder suspension or paste using inkjet technology, and fusing the glass powder using a scanning laser beam having a tailored beam profile. The local seal may be used in conjunction with a continuous thin film encapsulation structure. Optical functions can be provided by each local seal, including refraction, filtering, color shifting, and scattering.
1. A method of manufacturing local encapsulation seals over a two-dimensional array of organic electro-optical elements, the method comprising:
a. depositing a first drop of a glass powder suspension over a first electro-optical element using an inkjet dispenser;
b. depositing a second drop of the same glass powder suspension over a second electro-optical element;
wherein the first and second electro-optical elements are neighbors, and the first and second drops are not in contact with each other; and
c. fusing the first and second drops of glass powder, thereby to form respective first and second local encapsulation seals of fused glass, using at least one laser beam;
wherein the temperature of the glass powder in the first drop is maintained at a temperature less than or equal to 300° C. during the fusing step, and
an area between the first and second local encapsulation seals remains uncovered by fused glass.
2. The method of claim 1 , wherein the electro-optical element is an OLED light-emitting element.
3. The method of claim 1 , wherein the depositing step is preceded by formation of a thin-film encapsulation seal extending over the entire two-dimensional array of electro-optical elements.
4. The method of claim 1 , wherein the fusing step is followed by formation of a thin-film encapsulation seal extending over the entire two-dimensional array of electro-optical elements.