STATIC ELECTRONIC PHOTOFLASH ASSEMBLY AND METHOD OF PHOTOFLASH LIGHTING

摘要

A static electronic photoflash assembly and method of photoflash lighting is provided for reliably and selectively sequentially flashing at least one of an array of N flashbulbs with a start-flash electrical signal developed by a camera shutter actuated switch or other similar electrical signal producing device. The static electronic photoflash assembly is coupled to and controlled by the start-flash electric signal and is electrically coupled to and controls the array of N flashbulbs for selectively sequentially flashing at least one of the N bulbs. For this purpose, the static electronic control circuit includes enabling logic circuitry for identifying and establishing through the use of solid state semiconductor devices enabling electric circuit connections to at least one unflashed bulb in an array of N bulbs in advance of the bulb being flashed. For this purpose the logic circuit may comprise either a permanent memory type of logic circuit for remembering which of the N flashbulbs are unflashed, and for establishing enabling electric circuit connections to at least one unflashed bulb. Alternatively, the enabling logic circuit may comprise an arrangement for identifying and establishing the enabling circuit connections to an unflashed bulb at the instant that the start-flash electrical signal occurs. Preferably, the electronic control circuit further includes monitoring logic circuitry for sensing that a light flash has indeed occurred, and establishing enabling electric circuit connections to additional unflashed bulbs in the event that no light-flash has been produced for reliably selectively flashing at least one of the unflashed bulbs, preferably sequentially. The start-flash electrical signal generally is produced by a camera shutter actuated switch which maintains the static electronic control circuit energized throughout the camera shutter-open period, and the circuit is designed in a manner such that the time required for the static electronic control circuit to sense, enable, and flash all N flashbulbs in an array is less than the normal open period of the camera shutter. The photoflash assembly may comprise a separate attachment to a camera that includes permanently wired sockets that are selectively energized by a static electronic control circuit that is part of the attachment with the photoflash bulbs seated in the sockets being replaceable after flashing. Alternatively, the photoflash assembly may comprise a discardable throw-away type of an attachment to a suitably designed camera that includes the static electronic control circuit. In either form of the invention, the static electronic control circuit preferably is fabricated by integrated circuit techniques. The static electronic control circuit also preferably includes static electronic switching devices connected in series circuit relationship with the individual flashbulbs in the array, and the switching devices employed may comprise silicon controlled rectifiers, complementary SCRs, triacs, silicon controlled switches, silicon bilateral switches, silicon unilateral switches, gate turn-off silicon controlled rectifiers, field effect transistors, unijunction transistors, programmable unijunction transistors, equivalent discrete tranSistor configurations, and the like.