AN ELECTRONIC RETARD SENSOR FOR BOMB FUZES

ALTHOUGH CONVENTIONAL MASS-SPRING RETARD SENSORS ARE INEXPENSIVE, THEIR POOR RELIABILITY USUALLY REQUIRES THE USE OF TWO DEVICES IN PARALLEL TO ASSURE SWITCH CLOSURE. THE USE OF TWO DEVICES, HOWEVER, HAS AN ADVERSE AFFECT ON S&A SAFETY. G-SWITCHES USED AS RETARD SENSORS IN THE FMU-139 BOMB FUZE ARE CURRENTLY A MAJOR PROBLEM AREA IN THAT PROGRAM. THEIR POOR RELIABILITY IS DUE PRIMARILY TO IMPERFECTIONS IN THE MACHINED SURFACES, CONTAMINATION, AND TOLERANCE STACK-UP WHICH CAUSE HIGH CONTACT RESISTANCE OR LACK OF OPERATION ALTOGETHER. SILICON DESIGNS HAS DEVELOPED A MINIATURE, LOW-COST ACCELEROMETER THAT COMBINES A CAPACITIVE SENSE ELEMENT AND INTEGRATED SENSE ELECTRONICS IN A SINGLE IC PACKAGE. WE HAVE ALSO DEVELOPED AN ACCELERATION THRESHOLD DETECTION CIRCUIT THAT CAN BE INTEGRATED WITH THE SENSE ELECTRONICS. BECAUSE OUR CURRENT ACCELEROMETER'S HYBRID-BASED CONSTRUCTION AND LASER-TRIM CALIBRATION METHOD IS TOO COSTLY FOR USE IN BOMB FUZES, WE PROPOSE TO REDESIGN THE CALIBRATION CIRCUITS SO ALL CIRCUIT FUNCTIONS CAN BE INTEGRATED ONTO A SINGLE CUSTOM IC ALONG WITH THE SENSE ELEMENT. WE HAVE DESCRIBED A BASE-LINE DESIGN FOR SUCH A CHIP IN THIS PROPOSAL. THE RESULTING ELECTRONIC RETARD SENSOR IC WOULD BE VERY RELIABLE DUE TO ITS FABRICATION USING IC TECHNOLOGY.