Development of colour-mark sensor-based calibration system for timing devices with seven-segment liquid-crystal-display

摘要

There is a need for a better calibration system of timing devices at the National Metrology Laboratory, SIRIM Berhad (NML-SIRIM), particularly stopwatches and timers with seven-segment LCD. This research is focused on the development of a prototype calibration system which is based on the idea of utilizing a colour-mark sensor. It comprises of the process of predefining key specifications, designing a new calibration method, constructing a prototype measuring instrument and performing an experimentation test and finally carrying out an evaluation performance test via bilateral comparison with the existing calibration system of NML-SIRIM and also with the National Measurement Institute of Netherlands (VSL). To the best of the author's knowledge, there are as yet no reference publications or reports of calibration system involving the use of colour-mark sensor for the calibration of timing devices. Based on the observation and data analysis of the conducted experimentation tests, it shows that the developed prototype or so called the colour-mark sensor based calibration system can operate regardless of the intensity of ambient light and the measurement uncertainty is not constrained either by human reaction time or by resolution of the timing device being tested. Instead it is limited by the sensor reaction time and the counting capabilities of the prototype calibration system. There is also no need to dismantle the casing of the timing device under test in performing the calibration. Furthermore, the functionality of the timing device under test in counting the time can also be tested. The results from bilateral comparison show that the best measurement uncertainty of this prototype calibration system is ± 0.016 seconds per day, which is comparable to the best existing calibration method mentioned in this thesis.