The present invention is directed to light bulbs sheathed in silicone which protects the bulb from damage and contains the debris, including the toxic mercury, if the bulb should break.

Background of the invention

Compact fluorescent lamps ("CFLs") have become increasingly popular. They generate less heat, draw less electrical current, and are more energy efficient than standard incandescent bulbs. According to recent government statistics, if every American home replaced just one light bulb with an Energy Star approved CFL, the United States would save enough energy to light more than 2.5 million homes for a year and prevent greenhouse gases equivalent to the emissions of nearly 800,000 cars.

CFLs, however, contain small amounts of mercury. This is problematic if the CFL breaks since mercury is highly toxic. The present invention is directed to correcting this problem by providing a CFL sealed in a silicone sheath. If the CFL breaks, the mercury as well as the glass and other debris from the bulb, is safely contained within the sheath.

Brief summary of the invention

The object of this invention is to provide a light bulb, such as a CFL, that is sealed by a protective silicone sheath. The silicone sheath is fitted over a glass bulb which is then sealed with epoxy to the ballast base of the CFL. In the alternative, the lamp burner can be dipped into a silicone-glue slurry or the slurry can be poured over the burner, and then epoxied onto the back of the plastic base. The resulting sealed construction will contain the mercury vapor and other dangerous debris within the silicone sheath if the CFL should break.

The silicone-covered CFL is shatter-resistant and may be used with a higher degree of safety than regular non-protected bulbs in sensitive areas such as commercial kitchens, hospitals, laboratories, schools, and nurseries.

In addition to the safe and effective mercury containment system, the silicone- covered CFL of the present invention, by virtue of the epoxy sealant, is water-resistant. This improves the useful life of the bulb in humid conditions. The silicone covering also expedites heat transfer which results in a lower bulb temperature and longer bulb life.

The silicone sheath or coating may be made in any of a myriad of colors and may be used over clear or frosted glass.

The present invention may be adapted for use with fluorescent tubes, by attaching the silicone at the ends of the tube, as well as for cold cathode fluorescent lamp and induction lighting, which would be attached in a manner similar to that used for CFLs.

Brief description of the drawings

Fig. 1 is a view of the silicone sheath of the present invention. Fig. 2 is a view of the silicone sheath being fit over a glass globe. Fig. 3 is a view of the CFL tubing connected to the ballast base. Fig. 4 is a view of the assembled sheathed CFL. Fig. 5 is a cross-sectional view of Fig. 4 taken at line 5 - - 5. Fig. 6 is a view of a shattered CFL of the present invention. Detailed description of the invention

Fig. 1 shows a preferred embodiment of the silicone sheath 10 of the present invention. The sheath is manufactured from standard silicone film compositions. The thickness of sheath 10 is preferably between about 5 to 7 mils which provides the necessary strength and flexibility required by this application. The sheath has a closed rounded top portion 11 and an open end 12.

Fig. 2 shows sheath 10 as it is partially fitted over glass globe 20 which encases the CFL burner 30, shown in Fig. 3. Sheath 10 is then pulled fully over globe 20 such that open end 12 is aligned with the open edge (not shown) of globe 20. Fig. 5 shows a cross-sectional view of globe 20 covered by sheath 10. An epoxy glue bead is applied to the globe edge and sheath open end 12. The globe edge is then fit into cavity 32 of ballast base 31 of the CFL. The assembled product is shown in Fig. 4.

A second preferred embodiment is to coat burner 30 of Fig. 3 with a silicone glue solution, wherein the main component is silicone dioxide, mSiO ₂ nH ₂ O, an odorless and non-toxic solution. Because the particle size is 10-20 nm, it is transparent and does not affect the color of the object that is coated. Colored pigments, however, may be added to the silicone solution if desired, in which case the coating will not be transparent but will be colored. Burner 30 is dipped into the silicone glue solution and slowly rotated continuously at 25°C for 20 minutes or until the thickness of the coating has a thickness of approximately 0.2 mm to 0.4 mm, and preferably 0.3 mm. Maintaining the slow rotation, the silicone coated burner is then heated in an oven for 30 minutes at 150 ⁰ C to vaporize the water. Once dried, the ends 33 of burner 30 are inserted into the base 31 through holes 34. A bead of epoxy is applied to around ends 33 so that they are sealed to base 31.

An alternative method of coating the CFL of Fig. 3 is to pour the silicone glue solution over a slowly continuously rotating burner 30 at 25°C for 20 minutes or until the thickness of the coating has a thickness of approximately 0.2 mm to 0.4 mm, and preferably 0.3 mm. Maintaining the slow rotation, the silicone coated burner is then heated in an oven for 30 minutes at 150 ⁰ C to vaporize the water. Once dried, the ends 33 of burner 30 are inserted into the base 31 through holes 34. A bead of epoxy is applied to around ends 33 so that they are sealed to base 31.

If the globe and the fluorescent tubing of the CFL of the present invention is broken or cracked, the silicone sheath contains the debris, including the mercury, in a sealed sack 60, e.g., as shown in Fig. 6.