Broken Drill Bit Detector
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
A folded optical path enables a modular light source and its sensor to be protected and thus more reliably mounted and operated. In the figure, a bracket 1 has mounted on its underside light source 2 and sensor 3. The outer portion 4 of the bracket is formed with openings 5 and 6, and carries two mirrors 7. The bracket is mounted for oscillation on shaft 8 between an advanced position encompassing drill bit 9 in chuck 10 and a retracted position away from the drill bit. When the bracket is in the advanced position shown, light from source 2 passes through opening 5, being reflected from surfaces 7, where it is blocked by drill bit 9. If the drill bit is present, sensor 3 experiences a change in illumination and produces a corresponding change in signal level.