Display backing

A system, comprising:

• a head-mounted device (HMD), comprising:
• a display;
• a metal backing plate;
• and
• a coil;
• and
• a peripheral device;
• wherein the coil is configured to generate a magnetic field;
• wherein the peripheral device is configured to detect the magnetic field generated by the coil to estimate distance of the peripheral device to the HMD;
• and
• wherein the backing plate includes at least one perforation configured to reduce an eddy current in the backing plate caused by the magnetic field, wherein reducing the eddy current in the backing plate improves power efficiency of the coil, wherein the at least one perforation is placed along a path of the eddy current.

A method, comprising:

• generating, by a coil in a head-mounted display (HMD), a magnetic field;
• detecting, by a peripheral device, the magnetic field generated by the coil;
• estimating position of the peripheral device relative to the HMD based at least in part on the detected magnetic field at the peripheral device;
• and
• causing, by the magnetic field, an eddy current in a metal backing plate of the HMD, wherein at least one perforation formed in the backing plate interferes with the eddy current caused by the magnetic field to reduce the eddy current, wherein the at least one perforation is placed along a path of the eddy current;
• wherein reducing the eddy current in the backing plate improves power efficiency of the coil.