US Patent 7832900 Lightbulb with envelope-fracture responsive electrical disconnect means

A safety lightbulb includes a base, a glass envelope connected to the base, and electrical contacts extending from the base into the glass envelope and electrically connected to a filament for producing light in the glass envelope when current is supplied to the electrical contacts from a power source to which the base is connected. A safety arrangement in the base automatically electrically disconnects the electrical contacts from the power source when the glass envelope is broken, and includes an electrical contact member in the base and a moving/restraining arrangement in the base for moving the electrical contact members out of electrical contact with the power source and the electrical contacts, when the glass envelope is broken.