AN APPARATUS AND METHOD FOR DETECTING AND RECORDING A STRING OF ALPHA-NUMERIC CHARACTERS ON A SURFACE OF A FERRO-MAGNETIC COMPONENT

摘要

Apparatus for detecting and recording an engraved character string (3) on a gas cylinder (6) comprises a scanning unit (20) within which is mounted a permanent magnet (33) for generating a magnetic field between the magnet (33) and the surface (5). A plurality of magnetoresistive sensors (34) are arranged in an elongated array (35) and are located in a scanning face (31) in the scanning unit (20) for detecting the magnetic field and variations therein caused by the character string (3). A rotary encoder (40) monitors incremental distances travelled by the scanning unit (20). A control circuit (44) within the scanning unit (20) sequentially reads signals from the magnetoresistive sensors (34) as the scanning unit (20) travels through respective predetermined incremental distances. The distances are stored together with the respective signals from the magnetoresistive sensors (34) and from these stored signals character recognition software can construct and recognise the characters (4) of the character string (3).