Hall probe applications:

Recently, the Hall effect has been used in portable electronics:

Open/Close detection:

Laptops, mobile phones, and other portable devices with a rotating hinge and clam-shell design (see Figure 26.03) had historically used mechanical switches to indicate an open or closed position. It is essential to the status of the device as opened or closed to apply power to the sleeping circuitry and for returning the device to the sleep mode to conserve power.

Figure 26.03: Application of Hall effect in consumer electronics.

In recent cell phone, digital cameras and other portable instruments, a Hall effect integrated chip (IC) switch and magnet combination is used. The IC is often a unipolar Hall effect IC, which operates when a magnetic field of sufficient strength and polarity is detected.

Similarly, omnipolar Hall effect IC switches capable of detecting a magnetic field of either polarity can also be used. Unipolar devices typically require less power to operate but the magnet must be properly oriented, while omnipolar devices operate without regard to magnet orientation.