Photosensitive rear warning signal

Claim 1

IN COMBINATION WITH A VEHICLE HAVING A REARWARDLY DIRECTED LAMP AND A VOLTAGE SOURCE, A WARNING SYSTEM FOR INDICATING TO THE OPERATOR OF A SUCCEEDING VEHICLE THAT HE IS TOO CLOSE FOR DRIVING SAFETY AND COMPRISING AN ELECTROMAGNETIC RELAY INCLUDING AN ARMATURE, A SWITCH HAVING A MOVABLE CONTACT AND FIRST AND SECOND STATIONARY CONTACTS, SAID MOVABLE CONTACT BEING AUTUABLE BY SAID ARMATURE, CIRCUITS MEANS CONNECTING THE MOVABLE CONTACT WITH THE SOURCE, CIRCUIT MEANS INCLUDING A FLASHER UNIT CONNECTING THE FIRST STATIONARY CONTACT WITH THE LAMP, CIRCUIT MEANS CONNECTING THE SECOND STATIONARY CONTACT WITH THE LAMP, AND LIGHT RESPONSIVE MEANS ON SAID VEHICLE AND POSITIONED TO RECEIVE LIGHT FROM THE HEADLIGHTS OF A SUCCEEDING VEHICLE, SAID LIGHT RESPONSIVE MEANS CONNECTED WITH THE SOURCE FOR DEVELOPING A SIGNAL QUANTITY CORRESPONDING TO THE INTENSITY OF LIGHT RECEIVED FROM THE HEADLAMPS OF A SUCCEEDING VEHICLE, THE RELAY ACTUATED SWITCH INCLUDING A RELAY COIL CONNECTED WITH THE LIGHT RESPONSIVE MEANS FOR ENERGIZATION THEREBY AND FOR ACTUATING THE MOVABLE CONTACT SO AS TO SELECTIVELY CONNECT THE MOVABLE CONTACT WITH THE FIRST AND SECOND STATIONARY CONTACTS TO RESPECTIVELY ALTERNATELY OR CONSTANTLY ENERGIZED THE LAMP WHEN THE INTENSITY OF LIGHT RECEIVED FROM A SUCCEEDING VEHICLE IS RESPECTIVELY ABOVE OR BELOW A PREDETERMINED VALUE.