Light sensitive slave unit

Claim 1

A REMOTELY CONTROLLED FLASH UNIT COMPRISING A FOUR LAYER SEMICONDUCTOR SWITCHING DEVICE HAVING A GATE, EMITTER AND COLLECTOR, SAID DEVICE BEING OF THE TYPE WHICH IS SWITCHED ON BY BIASING ITS GATE WITH RESPECT TO ITS EMITTER WITH VOLTAGE OF ONE POLARITY AND IS SWITCHED OFF BY BIASING ITS GATE WITH RESPECT TO ITS EMITTER WITH VOLTAGE OF THE OPPOSITE POLARITY, A LOW VOLTAGE BATTERY AND A FLASHBULB SOCKET CONNECTED IN SERIES WITH THE EMITTER AND COLLECTOR OF THE FOUR LAYER SEMICONDUCTOR SWITCHING DEVICE SO THAT ALL CURRENT DRAWING CIRCUITS THROUGH SAID SOURCE WILL BE OPEN WHEN SAID FLASHBULB SOCKET IS EMPTY, A PHOTOSENSITIVE MEANS AND A RESISTOR CONNECTED IN SERIES BETWEEN THE EMITTER AND THE COLLECTOR OF THE FOUR LAYER SEMICONDUCTOR SWITCHING DEVICE, AND CIRCUITS MEANS COUPLING THE JUNCTION OF THE PHOTOSENSITIVE MEANS AND THE RESISTOR TO THE GATE OF THE FOUR LAYER SEMICONDUCTOR SWITCHING DEVICE TO BIAS THE FOUR LAYER SEMICONDUCTOR SWITCHING DEVICE NONCONDUCTING AND TO TRANSMIT CHANGES IN CURRENT FLOW THROUGH THE PHOTOSENSITIVE MEANS TO THE GATE OF THE FOUR LAYER SEMICONDUCTOR SWITCHING DEVICE AND THEREBY TRIGGERING THE FOUR LAYER SEMICONDUCTOR SWITCHING DEVICE CONDUCTING WHEN A FLASHBULB IS PROPERLY INSERTED IN SAID FLASHBULB SOCKET, SAID CIRCUIT MEANS INCLUDING A DIFFERENTIATING CIRCUIT MEANS WHICH PREVENTS STEADY STATE CURRENT FLOW THROUGH THE PHOTOSENSITIVE MEANS FROM TRIGGERING THE FOUR LAYER SEMICONDUCTOR SWITCHING MEANS CONDUCTIVE AND CAPACITIVE CIRCUIT MEANS WHICH PREVENTS CURRENT TRANSIENTS DUE TO INSERTION OF FLASHBULBS IN THE FLASHBULB SOCKET FROM TRIGGERING THE FOUR LAYER SEMICONDUCTOR SWITCHING DEVICE CONDUCTIVE.