Patent ID: 11922892
Assignee: META PLATFORMS TECHNOLOGIES, LLC
Field: Electrical machinery, apparatus, energy (Electrical engineering)
Classification: CPC G  H | IPC G

Claim 13:
14. A method, comprising:
receiving a device input voltage;
boosting the device input voltage to obtain a backlight drive voltage; and
driving a backlight unit using the backlight drive voltage,, wherein:
the backlight unit comprises an arrangement of light-emitting diodes (LEDs); and
boosting the device input voltage comprises:
obtaining a pulse modulation signal from an analog pulse modulation circuit, wherein:
the analog pulse modulation circuit is configured to provide a pulse modulation signal having a duty ratio to a voltage boost circuit and comprises a pulse width modulation controller, a loop gain adjuster, and an analog-to-digital converter configured to receive a headroom signal from a driver circuit and to provide a control signal to the loop gain adjuster, thereby adjusting the analog pulse modulation circuit;

the device input voltage is between 3 V and 4.5 V;
the backlight drive voltage is between 20 V and 40 V;
the duty ratio is in a range of 5% to 20%;
the pulse modulation controller is configured to adjust the pulse modulation signal based on the headroom signal;
the device has an input power factor of greater than 0.9;
a loop gain of the pulse modulation controller is adjusted based on the headroom signal; and
the device is a head-mounted device.