The flux from an in circuit permanent magnet is varied as the relative movement between {TAIL ~ opposed teeth} of {HEAD ~ sensor} and platen changes 
The flux from an in circuit permanent magnet is varied as the relative movement between { TAIL ~ opposed teeth } of { HEAD ~ sensor } and platen changes
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH