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US 4,336,570 AGranted
Radiation switch for photoflash unit
AssigneeGTE Products Corporation
InventorsBoyd G. Brower, Gary L. Houseknecht
Life of this patent
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AssigneeGTE Products Corporation
InventorsBoyd G. Brower, Gary L. Houseknecht
Estimating the term…
A photoflash unit having a plurality of flashlamps mounted on a printed circuit board containing circuitry for sequentially igniting the flashlamps in response to successive firing pulses applied thereto. The circuitry includes a plurality of solid-state switches capable of being activated by radiant energy generated during flashing of lamps located adjacent to respective switches. Initially, each of the switches has a resistance sufficiently high to provide an open circuit to the applied firing pulses, and after being activated by radiation, the switch undergoes chemical conversion to a conductive state over a finite time interval. The switches are prepared from compositions comprising admixtures of silver carbonate and/or silver oxide, silver-coated glass beads and a binder; the admixtures may also include electrically non-conductive particulate solids, such as titanium dioxide, and/or silver-coated metal beads. The constituents and proportions of the switch compositions are selected to provide a predetermined conversion time of twelve milliseconds or greater, thereby permitting reliable functioning with comparatively long duration, low voltage firing pulses.
A radiation switch for a photoflash unit which is capable of conversion from a high electrical resistance to a low electrical resistance over a finite time interval when exposed to radiation emitted from a flashlamp disposed adjacent to the switch, said switch comprising an admixture of silver carbonate and/or silver oxide, silver-coated glass beads, and a binder, wherein the composition of the mixture is selected to provide a predetermined conversion time of about 12 milliseconds or greater.
In a multilamp photoflash unit comprising a pair of flashhlamps, an electrical circuit into which said lamps are arranged to fire individually and in sequence, and a solid state radiation switch located external of the lamps and forming part of said electrical circuit, said switch being located adjacent one of said flashlamps to receive radiant energy emitted by that flashlamp and being capable of conversion from a high electrical resistance to a low electrical resistance over a finite time interval upon receiving said emitted radiant energy, the improvement wherein said radiation switch comprises an admixture of material including silver carbonate and/or silver oxide, silver-coated glass beads, and a binder, wherein the composition of the mixture is selected to provide a predetermined conversion time of about 12 milliseconds or greater.
Dependencies are inferred from the claim text.