Shaft angular velocity monitor - uses stroboscopic effect to give illuminated display of any velocity error of e.g. turntable

摘要

In its basic form the monitoring appts. consists of a light source pulsed typically at 50 Hz, which directs a light beam at a slotted screen attached to the shaft concerned. The slots are spaced according to the nominal shaft frequency being monitored. On the far side of the screen a benched row of light pipes - each attached to a lens display - monitors the flashing light beam through the passing slots. The effect is that the middle lens display is lit only if the shaft velocity is at its nominal value. Displays to the right or left are lit for a phase lag or lead, and a travelling display corresponds to a velocity error. Double rows of slots for monitoring two velocities are also described.