Inspection apparatus for transparent glass sheets

Claim 1

AN INSPECTION APPARATUS FOR TRANSPARENT GLASS SHEETS, COMPRISING A CONVEYOR FOR SUPPORTING AND MOVING A SHEET FORWARD ALONG A SUBSTANTIALLY HORIZONTAL PATH, A LIGHT SOURCE FOR DIRECTING A BEAM OF LIGHT AT AN ANGLE ON A SHEET, A LIGHT PICK-UP UNIT FOR RECEIVING THE LIGHT BEAM FROM THE LIGHT SOURCE WHICH IS REFLECTED FROM THE SHEET, POLARIZED LIGHT EMITTING MEANS POSITIONED AT ONE SIDE OF THE SHEET BETWEEN THE LIGHT SOURCE AND THE PICK-UP UNIT AND AN ANALYZER FOR RECEIVING POLARIZED LIGHT RAYS FROM SAID POLARIZED LIGHT EMITTING MEANS POSITIONED AT THE OPPOSITE SIDE OF THE SHEET IN ALIGNMENT WITH SAID POLARIZED LIGHT EMITTING MEANS, A TIMER FOR PRODUCING A SIGNAL AFTER A PREDETERMINED TIME LAPSE, FIRST CIRCUIT CONTROL MEANS ELECTRICALLY CONNECTED WITH AND INTERPOSED BETWEEN THE LIGHT PICK-UP UNIT AND THE TIMER AND OPERABLE TO ACTIVATE SAID TIMER WHEN ENERGIZED BY SAID LIGHT PICK-UP UNIT IN RESPONSE TO THE LIGHT REFLECTED FROM THE SHEET, A MOTOR FOR DRIVING SAID CONVEYOR, NORMALLY OPEN SWITCH MEANS ELECTRICALLY CONNECTED WITH AND INTERPOSED BETWEEN THE MOTOR AND THE TIMER, SAID SWITCH MEANS CLOSING IN RESPONSE TO SAID SIGNAL FROM SAID TIMER TO HALT THE OPERATION OF SAID MOTOR, A SECOND CIRCUIT CONTROL MEANS, A LIGHT METER ELECTRICALLY CONNECTED WITH AND INTERPOSED BETWEEN SAID SECOND CIRCUIT CONTROL MEANS AND SAID ANALYZER AND OPERABLE TO ENERGIZE SAID SECOND CIRCUTI CONTROL MEANS WHEN A PREDETERMINED AMOUNT OF POLARIZED LIGHT PASSES THROUGH SAID SHEET AND IS RECEIVED BY THE ANALYZER, A NORMALLY CLOSED SWITCH ELECTRICALLY CONNECTED WITH THE SECOND CIRCUIT CONTROL MEANS AND INTERPOSED BETWEEN THE FIRST CIRCUIT CONTROL MEANS AND THE TIMER, SAID NORMALLY CLOSED SWITCH BEING OPENED TO BREAK THE CIRCUIT TO SAID TIMER UPON ENERGIZING OF SAID SECOND CIRCUIT CONTROL MEANS BY SAID LIGHT METER THEREBY DE-ACTIVATING THE TIMER TO ALLOW CONTINUED OPERATION OF THE MOTOR, SAID SECOND CIRCUIT CONTROL MEANS BEING INOPERABLE WHEN INSUFFICIENT POLARIZED LIGHT PASSES THROUGH THE SHEET TO SAID ANALYZER PERMITTING CONTINUED OPERATION OF SAID TIMER.