Investigations of piezoelectric force measuring devices for use in legal weighing metrology

In conjunction with low-drift charge amplifiers, static force and weighing measurements become increasingly important for piezoelectric force transducers if the measuring time and the time of load change are in the range of a few minutes. The investigations according to the international recommendation OIML R60 (International Recommendation OIML R60 for load cells, Edition 2000, Bureau International de Métrologie Légale, Paris, France), which are presented here illustrate that piezoelectric sensors can be used for static applications with low-accuracy requirements (e.g. class D for ordinary-accuracy weighing instruments). With suitable methods for the compensation or adjustment, the sensors even meet the higher requirements of medium accuracy class C (e.g. commercial scales). Especially for high-nominal loads, the piezoelectric measurement technology offers unused potential also for static precision measurements.