Method of manufacturing sealing device and display device using the same

A method of manufacturing a display device having first and second substrates and a sealing material, the method comprising:

• providing a mask comprising a transmission portion;
• irradiating light on the mask;
• regulating the energy profile of the light irradiated across the sealing material interposed between the first and second substrates;
• and
• bonding the sealing material to the first substrate and the second substrate,
• wherein the transmission portion comprises a first region with a predetermined constant transmittance at a central portion, a second region with a single predetermined transmittance constant throughout the second region provided on both sides of the first region, and a third region with a single predetermined transmittance constant throughout the third region provided on both outer sides of the second region, and wherein the transmittances of patterns of the first region, the second region, and the third region are different from each other;
• wherein the first region, each part of the second region on either side of the first region and each part of the third region on either side of the second region are substantially the same size;
• and
• wherein the first, second, and third regions each comprise different line-shaped patterns comprising a plurality of opaque lines, and wherein the transmittance is controlled by the density of the opaque lines of the patterns.