Incandescent lamps having protection against voltage surges

Claim 2

A voltage surge protected incandescent lamp comprising: a filament; an envelope for containing said filament in an oxidizing agent excluding atmosphere; and polycrystalline varistor means connected electrically in parallel with said filament for shunting voltage surges to protect said filament therefrom.

Claim 3

The surge protected lamp of claim 1 wherein: said lamp further comprises a base member including two conductive members for connecting said filament to a source of electrical energy; and said polycrystalline varistor means is disposed between said conductive members in electrical and mechanical contact therewith.

Claim 4

The surge protected lamp of claim 1 wherein: said lamp further comprises a base member including two conductive members for connecting said filament to a source of electrical energy and an insulating member disposed between said conductive members; and said polycrystalline varistor means comprises a body of polycrystalline varistor material having a pair of opposed faces, each of said opposed faces being electrically connected to a corresponding one of said pair of conductive members.

Claim 5

The surge protected lamp of claim 1 wherein said polycrystalline varistor means is a body of polycrystalline varistor material comprising zinc oxide as a major constituent and a minor constituent selected from the group consisting of other metal oxides and halides.

Claim 6

The surge protected lamp of claim 4 wherein said body has a varistor Alpha exponent in excess of 10 in the current density range of 10 3 to 102 amperes per square centimeter.

Claim 7

The surge protected lamp of claim 1 wherein said polycrystalline varistor means is adapted to be inserted in a lamp socket and comprises: a body of polycrystalline varistor material having a pair of substantially parallel opposed faces and a void in said body extending from a first of said faces to a second of said faces; first conductor means connected to said first face for providing electrical connection between said first face and a center contact of a lamp socket; second conductor means connected to said first conductor means and traversing said void for providing electrical connection between said first conductor means and a center contact of a lamp base; and third conductor means connected to said second face for providing electrical connection between said second face anD a shell contact of a lamp socket.

Claim 8

The surge protected lamp of claim 6 wherein said third conductor means is a conductive spring member and further including: means responsive to compressive forces provided by a lamp base secured in said lamp socket for urging said conductive spring member into contact with said shell contact.

Claim 9

The surge protected lamp of claim 7 wherein said means responsive to compressive forces comprises: an extension of said second conductor means depending toward said third conductive means; and insulator means disposed between said extension and said third conductor means for transmitting mechanical forces and preventing electrical contact therebetween.

Claim 10

The surge protected lamp of claim 6 wherein said body of polycrystalline varistor material comprises zinc oxide as a major constituent and a minor constituent selected from the group consisting of other metal oxides and halides.

Claim 11

The surge protected lamp of claim 9 wherein said body has a varistor Alpha exponent in excess of 10 in the current density range of 10 3 to 102 amperes per square centimeter.

Claim 12

A surge protective device adapted to be inserted in a lamp socket comprising: a body of polycrystalline varistor material having a pair of substantially parallel opposed faces and a void in said body extending from a first of said faces to a second of said faces; first conductor means connected to said first face for providing electrical connection between said first face and a center contact of a lamp socket; a second conductor means connected to said first conductor means and traversing said void for providing electrical connection between said first conductor means and a protected device; and third conductor means connected to said second face for providing electrical connection between said second face and a shell contact of said lamp socket.

Claim 13

A surge protective device adapted to be inserted in a lamp socket comprising: a body of polycrystalline varistor material having a pair of substantially parallel opposed faces and a void in said body extending from a first of said faces to a second of said faces; first conductor means connected to said first face for providing electrical connection between said first face and a center contact of a lamp socket; a second conductor means connected to said first conductor means and traversing said void for providing electrical connection between said first conductor means and a protected device; and third conductor means connected to said second face for providing electrical connection between said second face and a shell contact of said lamp socket.