Hall element differential array based ferromagnetic construction member surface crack detector

The invention relates to a Hall element differential array based ferromagnetic construction member surface crack detector, comprising a differential array type flux leakage probe, a displacement detecting unit, a signal conditioning circuit and a data acquisition unit; wherein Hall sensors arranged on one surface of a probe circuit board are arranged in a regular array, the Hall sensor group of the probe is arranged at the upper and lower sides of the circuit board in a differential way, two voltage signals are respectively output to the signal conditioning circuit, so as to form a reflective flux leakage voltage signal, and the voltage signal is input into the data acquisition unit. The invention can conveniently detect the size and position of crack defect and has the advantages of large detection area, fast speed and low defect omission ratio.