Magnetic bar code reading system employing phase-shift type sensor having plural sensing sections

A pattern reading system comprising:

• an object having a main body which has at least one part thereof formed of a magnetic portion, and a recording area located at a predetermined portion of said magnetic portion, said recording area having a surface partially hardened to integrally include a desired pattern on the basis of permeability difference which depends on presence or absence of hardening on the surface,
• scanning means for scanning said pattern, said scanning means having sensor means displaceable relative to said pattern for scanning the same, said sensor means having coil means which is excited by a reference ac signal to produce an induced output signal, said induced output signal representing the difference in permeability in the pattern when said coil means is positioned to be affected by the pattern;
• and
• signal forming means responsive to the induced output signal from said coil means for forming a pattern signal representing the pattern in correspondence with the difference in permeability.

A coded pattern information reading system comprising:

• a recorded pattern having first and second patterns in parallel to each other, said first pattern being formed of first and second pattern elements which are provided in an arrangement representing an entire coded information and which exhibit different reluctance characteristics, said second pattern being formed of first and second pattern elements which exhibit different reluctance characteristics and which are provided in an arrangement having a reluctance relationship opposite to the arrangement of said first and second pattern elements of said first pattern;
• scanning means for scanning said patterns by approaching said pattern recording means, said scanning means having sensor means displaceable relative to said patterns for scanning the same, said sensor means having first and second sensing sections excited by an ac signal to produce an induced output signal, said sensing sections being spaced from each other in a direction substantially perpendicular to a direction in which said sensor means scans the pattern, in such manner that, when scanning the pattern, the first sensing section approaches the first pattern while the second sensing section approaches the second pattern, whereby said induced output signal is produced in correspondence with said pattern;
• and
• signal forming means responsive to the induced output signal from said sensor means for forming a signal determining information represented by said pattern.

A coded pattern information reading system comprising:

• a recorded pattern including at least a first pattern, said first pattern being formed of first and second pattern elements which are provided in an arrangement representing an entire coded information and which exhibit different reluctance characteristics;
• scanning means for scanning said pattern by approaching said pattern, said scanning means having sensor means displaceable relative to said pattern for scanning the same, said sensor means having first, second and third sensing sections each excited by an ac signal to produce an induced output signal, said second and third sensing sections being disposed at both sides of the first sensing section and said first, second and third sensing sections being spaced from each other in such a manner that, when said sensor means scans the pattern, the first sensing section is adjacent the first pattern while the other sensing sections are not;
• and
• signal forming means responsive to the induced output signal from said sensor means for forming a signal determining information represented by said pattern.