Light emitting device having a particular sealing structure

1. A light-emitting device comprising:

an element substrate having a light-emitting element formed thereon; and

a sealing substrate to seal the light-emitting element, the sealing substrate including:

a first substrate which has a hollow portion formed in a first surface thereof, a plate portion forming a bottom surface of the hollow portion, and a frame portion forming an inner wall surface of the hollow portion, the frame portion attached to the element substrate with an adhesive so as to secure a space between the element substrate and the sealing substrate, and

a second substrate attached to a second surface of the first substrate, the second substrate formed of a material of a specific gravity lower than a specific gravity of the first substrate, the second substrate being formed of resin.

2. The light-emitting device according to claim 1 , wherein the first substrate is formed of an inorganic oxide.

3. The light-emitting device according to claim 2 , wherein the first substrate is formed of an inorganic oxide selected from a group of glass, quartz, and ceramic.

4. The light-emitting device according to claim 3 , wherein the first substrate is formed of a glass selected from a group of soda-lime glass, borosilicate glass, aluminosilicate glass, and silicate glass.

5. The light-emitting device according to claim 1 , wherein the second substrate is a single layer.

6. The light-emitting device according to claim 1 , wherein the second substrate is formed of a material including a resin selected from a group of polyolefine, polyester, an ethylene vinyl acetate copolymer, an ethylene methyl methacrylate copolymer, and an ionomer resin.

7. The light-emitting device according to claim 1 , wherein the second substrate includes a plurality of layers.

8. The light-emitting device according to claim 7 , wherein the second substrate includes a base material layer and a layer for bonding or adhesion.

9. The light-emitting device according to claim 8 , wherein:

the base material layer is formed of a material including a resin selected from a group of polyethylene terephthalate, a polyamide, polyolefine, a polycarbonate, a polyimide, polyethel sulfonic acid, an epoxy compound, polystyrene, and a cellulose resin, and

the layer for bonding or adhesion is formed of a material including a resin selected from a group of silicone, an acrylic resin, a metacrylic resin, an epoxy compound, polyurethane, an ethylene vinyl acetate copolymer, and styrene-butadiene rubber.

10. The light-emitting device according to claim 8 , wherein the second substrate further includes a buffer layer.

11. The light-emitting device according to claim 10 , wherein the buffer layer is formed of a material including a resin selected from a group of styrene-butadiene rubber, silicon rubber, latex, and polyurethane.

12. The light-emitting device according to claim 1 , wherein:

the thickness of the first substrate is within the range of greater than or equal to 0.1 mm and less than or equal to 1.1 mm,

the height of the inner wall surface of the hollow portion is within the range of greater than or equal to 0.05 mm and less than or equal to 0.8 mm, and

the thickness of the plate portion is within the range of greater than or equal to 0.01 mm and less than or equal to 0.9 mm.

13. The light-emitting device according to claim 12 , wherein the thickness of the second substrate is within the range of greater than or equal to 0.01 mm and less than or equal to 0.4 mm.

14. The light-emitting device according to claim 13 , wherein the total thickness of the first and second substrates is within the range of greater than or equal to 0.1 mm and less than or equal to 1.5 mm.