The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 02, 1995
Filed:
Nov. 16, 1993
William F Marantette, Torrance, CA (US);
Optima Industries, Inc., Torrance, CA (US);
Abstract
Longitudinal position of the end of a drill bit (21) is determined in order to accurately control depth of a hole to be drilled. A drill bit (21) is rotated at a predetermined speed and caused to penetrate a light beam of known vertical position. The light beam, which is generated by a light emitting diode (50) and received by a photo transistor (54), is modulated by the flutes at the tip of the rotating bit to cause the photo transistor to provide an output signal that is modulated at a frequency that is a fixed multiple of the speed of the rotating bit. An operational amplifier (74) having a feedback circuit (80) that is resonant at the frequency of the modulated electrical signal from the photo transistor receives the photo transistor output signal as its input. The amplifier output experiences a sharp increase in magnitude upon receipt of the input signal at the resonant frequency of its feedback circuit. Thus a reference position of the bit is signalled and stored by the bit spindle control (18) that will move the bit longitudinally to a depth determined on the basis of the known bit reference position.