Heat spreader for emissive display device
A heat spreader for a display device, such as a plasma display panel, a light emitting diode or a liquid crystal display, comprising at least one sheet of compressed particles of exfoliated graphite having a surface area greater than the surface area of that part of the back surface of the display device where a localized region of higher temperature is generated.
1. A display device, comprising
a. a display panel which comprises a plurality of heat sources;
b. a heat spreader having two major surface and which comprises:
i. at least one sheet of compressed particles of exfoliated graphite having two major surfaces and a density of from about 0.8 g/cc to about 2.0 g/cc, one of the major surfaces of the at least one sheet of compressed particles of exfoliated graphite having a surface area greater than the surface area of at least one of the heat sources; and
ii. a facing layer adhered to one of the major surfaces of the at least one sheet of compressed particles of exfoliated graphite for being interposed between the sheet of compressed particles of exfoliated graphite and the display panel; and
c. a layer of adhesive for adhering the heat spreader to the display panel such that substantially all of one of the major surfaces of the heat spreader is in thermal contact with the display panel, the layer of adhesive consisting of a layer of an acrylic or latex adhesive no more than about 0.015 mm in thickness, wherein the adhesive bond between the heat spreader and the display panel is stronger than the structural integrity of the at least one sheet of compressed particles of exfoliated graphite and the structure of the facing layer is stronger than the adhesive bond between the heat spreader and the display panel.
2. The display device of claim 1 , wherein the display device is an emissive display device, and one of the major surfaces of the at least one sheet of compressed particles of exfoliated graphite has a surface area greater than the surface area of that part of a discharge cell facing the back surface of the emissive display device.
3. The display device of claim 2 wherein the emissive display device comprises a plasma display panel.
4. The display device of claim 3 wherein one of the major surfaces of the at least one sheet of compressed particles of exfoliated graphite has a surface area greater than the surface area of that part of a plurality of discharge cells facing the back surface of the plasma display panel.
5. The display device of claim 1 wherein the heat spreader comprises a laminate comprising a plurality of sheets of compressed particles of exfoliated graphite.
6. The display device of claim 5 wherein the laminate comprises layers of a non-graphitic material.
7. The display device of claim 1 wherein the layer of adhesive achieves an average lap shear adhesion strength of at least about 700 grams per square centimeter.
8. The display device of claim 7 wherein the thickness of the layer of adhesive is no greater than about 0.015 mm.
9. The display device of claim 8 wherein the at least one sheet of compressed particles of exfoliated graphite has edge surfaces, and at least one edge surface is coated with a protective coating sufficient to inhibit flaking of the particles of graphite.
10. The display device of claim 8 which further comprises a layer of adhesive interposed between the protective coating and the at least one sheet of compressed particles of exfoliated graphite.
11. The display device of claim 1 wherein at least one of the major surfaces of the at least one sheet of compressed particles of exfoliated graphite is coated with a protective coating sufficient to inhibit flaking of particles of graphite.
12. The display device of claim 11 wherein the protective coating comprises a metal or a thermoplastic material.
13. The display device of claim 12 wherein the protective coating is no more than about 0.025 mm in thickness.
14. The display device of claim 13 wherein the protective coating is effective to electrically isolate the coated major surface of the at least one sheet of compressed particles of exfoliated graphite.
15. The display device of claim 1 wherein the facing layer comprises a metal.