Smoke detecting device

Claim 1

A SMOKE DETECTOR, COMPRISING A CHAMBER HAVING A WALL STRUCTURE DARKENING THE INSIDE OF THE CHAMBER, THERE BEING SPACED SHIELDED APERTURES THROUGH SAID WALL STRUCTURE INTER-COMMUNICATING WITH EACH OTHER THROUGH SAID CHAMBER FOR ALLOWING AMBIENT ATMOSPHERE TO CIRCULATE THROUGH THE CHAMBER, A LIGHT SOURCE FOR PROJECTING A LIGHT BEAM ACROSS SAID CHAMBER, AND A LIGHT RESPONSIVE DEVICE SHIELDED FROM DIRECT LIGHT FROM THE LIGHT SOURCE AND BEING POSITIONED TO VIEW TRANSVERSELY A PORTION OF THE LIGHT BEAM, WHEREIN THE IMPROVEMENT COMPRISES LENS MEANS ASSOCIATED WITH THE LIGHT RESPONSIVE DEVICE TO RESTRICT THE FIELD OF VIEW OF THE LIGHT RESPONSIVE DEVICE IN THE CHAMBER BEYOND THE LIGHT BEAM TO AN AREA LESS THAN THE AREA OF THE FIELD OF VIEW WITHIN THE LIGHT BEAM, WHEREBY THE RATIO OF THE AMOUNT OF LIGHT TRANSMITTED THROUGH SAID LENS MEANS TO SAID LIGHT RESPONSIVE DEVICE WHEN PARTICLES OF SMOKE ENTER SAID CHAMBER AND REFLECT LIGHT FROM SAID REGION OF SAID BEAM, TO THE AMOUNT OF LIGHT TRANSMITTED THROUGH SAID LENS MEANS TO SAID LIGHT RESPONSIVE DEVICE WITHOUT SMOKE IN SAID CHAMBER, IS INCREASED SINCE SAID LENS MEANS HAS DECREASED AREA OF VIEW IN SAID REGION BEYOND SAID LIGHT BEAM AS COMPARED TO THE AREA OF VIEW IN SAID BEAM.