A unipolar Hall switch is a Hall switch that only senses one pole of a magnet, which means that one (S pole or N pole) magnetic pole is used to sense and trigger the Hall. Generally, the positive side senses the S pole of the magnetic field, and the reverse side senses the N pole. The silk screen surface senses the S pole, and when the magnet S approaches, the Hall switch changes from a high level to a low level. When the magnet moves away, the Hall switch outputs a high level again. However, when the magnet N pole approaches the reverse side, the Hall switch changes from a high level to a low level. When the magnet moves away, the Hall switch outputs a high level again. However, it does not mean that the unipolarity simply senses only one pole, but only senses one pole relative to the silk screen surface.