Vibration dosimeter

US4475401A · kind A · utility

Assignee

• The United States of America, as represented by the Department of Health and Human Services · US

Inventors

• David Punia · Burlington, US
• Malcolm H. Pope · Coralville, US
• Dennis D. Donnermeyer · Portsmouth, US

Key dates

• Filing date: May 20, 1982
• Grant date: Oct 9, 1984
• Expiry date: May 20, 2002

Classification

• Technology area (CPC G): Physics
• CPC primary: G01H1/00
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

An apparatus to monitor and record, for an industrial environment, two natural frequencies with respect to a "seated spinal system", namely, approximately 10 Hz and approximately 4 Hz, the natural resonant frequencies of the spine. Raw acceleration signals are amplified, conditioned and filtered to allow only 20 Hz or less to pass. The signals are then divided into two respective channels, namely, below 20 Hz and below 8 Hz, following parallel paths through an amplitude detector and through a zero crossover detector, rectifier and digital filter. In each path the amplitude detector controls a storage flip-flop, which enables an associated decade counter when amplitude criteria are met. The digital filter supplies an output, via an AND gate, to the counter if both amplitude and frequency criteria are met. Thus, a count is stored in the counter if both amplitude and frequency criteria are met. Each channel has an LED display which can be turned on, after exposure, to display the number of events recorded.