A High-Precision Production-Oriented Gage Utilizing A Solid State Image Sensor And Microprocessor

This paper describes a semi automatic gage comprised of a solidstate image sensor, a microprocessor, light source, fiber optics, lens system, and a mechanical fixture to measure the size and location of two small slots inside a diesel engine fuel injector nozzle. The slot widths and locations are measured to a resolution of .002 millimeters with a maximum measurement of 30 millimeters. Designed for production inspection, the operation is extremely simple and easily performed by an unskilled operator. This ease of operation also carries over into the calibration of the gage which takes about 15 seconds. During the calibration, a known master gage is measured by the system which then computes and stores in the microprocessor memory the scale factors and offsets of each of the measured variables. In operation, the production nozzles are measured using these stored scale factors and offsets, displayed in millimeters, and compared with the part tolerances stored in memory for an accept/fail indication. By replacing the fixturing and and modifying the computer program, the unit can be configured for a variety of high precision measurement and inspection applications.