Abstract: Improved fuse elements used with the circuit board to provide more reliable sequential firing in a flash lamp array. The circuit board includes a lamp firing circuitry along with radiation switches connected in said circuitry and more reliable fuse elements cooperate with said radiation switches in the circuit operation. The improved fuse elements are constructed as an integral part of the lamp firing circuit pattern deposited on the circuit board at circuit locations wherein the underlying circuit board substrate has a thickness less than the substrate thickness elsewhere to enhance melting or thermal decomposition of the circuit board substrate.

Abstract: A flash lamp array having a plurality of flash lamps positioned over a side of a circuit board having thereon circuitry for sequentially flashing the lamps. A metal shield, in the form of a sheet of metal foil or foil-covered paper, is positioned adjacent to the other side of the circuit board and is in contact with a common electrical run on the circuit board by means of a staple through the circuit board. Strips of radiation-sensitive plastic are positioned between the shield and the circuit board to function as electrical insulation, and also function as flash indicators by distorting due to radiation from an adjacent flashing lamp.