A study of the electrostatic potential on MR heads using metal powder tapes

The authors have measured the potential of electrostatic discharge using a commercial VCR drive with metal powder (MP) tapes that are widely used in business. They set up an experimental drive, which has a surface voltage meter and a magneto-resistive read (MR) head with a current-measuring circuit. Using this system, they can measure the surface voltage and current while the tape is running and can investigate how the electrostatic potential from the tape can damage the head. In their assumption that if the media surface voltage is low and current flowing into the head is lower than the sensing current of the head, the MR head can be used in a VCR. It can be not only AMR but may also be giant magnetoresistive and TMR in the future. The results of their experiments show that the peak surface voltage is low and the peak current is only about 3.6 μA with a middle-resistance tape. The peak current is lower than the breakdown current since the sensing current is typically 10 mA. Therefore, an MR head can be used with an MP tape. The authors found that the optimum surface resistance of middle-resistance tape is 10⁶ to 10⁷·Ωsq.