Timer

Claim 1

IN A CONTROL EQUIPMENT EFFECTIVE IN RESPONSE TO THE TRANSIENT CHANGE OF A LIGHT BEAM BY A MOVABLE OBJECT TO ACTUATE A LOAD DEVICE FOR A SELECTABLE INTERVAL OF TIME, THE COMBINATION OF RELAY MEANS HAVING TWO STABLE STATES, A PHOTOELECTRIC DEVICE IN THE PATH OF THE LIGHT BEAM, MEANS INCLUDING SAID PHOTOELECTRIC DEVICE AND FIRST TIMING MEANS RESPONSIVE TO A CHANGE OF THE ILLUMINATION ON SAID PHOTOELECTRIC DEVICE IN ONE DIRECTION FOR CHANGING THE STATE OF SAID RELAY MEANS FROM A FIRST TO A SECOND STATE FOR A PRESELECTED SHORT INTERVAL OF TIME AND EFFECTIVE THEREAFTER EVEN IN THE ABSENCE OF A SUBSEQUENT CHANGE OF THE ILLUMINATION ON SAID PHOTOELECTRIC DEVICE TO CHANGE THE STATE OF SAID RELAY MEANS FROM SAID SECOND STATE TO SAID FIRST STATE AT THE END OF SAID PRESELECTED SHORT INTERVAL OF TIME, A CAPACITOR, A RESISTOR, A SOURCE OF ENERGY, MEANS INCLUDING SAID RELAY MEANS AND SAID SOURCE AND EFFECTIVE WHILE SAID RELAY MEANS IS IN SAID SECOND STATE FOR CHANGING THE CHARGE ON SAID CAPACITOR IN ONE DIRECTION, MEANS INCLUDING SAID RESISTOR EFFECTIVE WHILE SAID RELAY MEANS IS IN SAID FIRST STATE FOR CHANGING THE CHARGE ON SAID CAPACITOR IN THE OPPOSITE DIRECTION AND AT A RATE CONTROLLED BY SAID RESISTOR, AND MEANS INCLUDING AMPLIFYING MEANS FOR OPERATING THE LOAD DEVICE WHILE THE CHARGE ON SAID CAPACITOR DIFFERS IN ONE DIRECTION FROM A PRESELECTED MAGNITUDE AND WHILE SAID RELAY MEANS REMAINS IN SAID FIRST STATE AND FOR RELEASING THE LOAD DEVICE WHEN THE CHARGE ON SAID CAPACITOR DIFFERS IN THE OTHER DIRECTION FROM SAID PRESELECTED MAGNITUDE.