US 11,922,892 B2
High-efficiency backlight driver
Yuming Liu, Mountain View, CA (US); Chao Hu, San Ramon, CA (US); Joaquin Andres Fierro, Los Gatos, CA (US); Nathan Slattengren, San Francisco, CA (US); David Viviescas, Mountain View, CA (US); Stella Chung, Fremont, CA (US); and Tajbid Rahman, Ozone Park, NY (US)
Assigned to Meta Platforms Technologies, LLC, Menlo Park, CA (US)
Filed by META PLATFORMS TECHNOLOGIES, LLC, Menlo Park, CA (US)
Filed on Jul. 13, 2021, as Appl. No. 17/374,929.
Claims priority of provisional application 63/139,533, filed on Jan. 20, 2021.
Prior Publication US 2022/0230597 A1, Jul. 21, 2022
Int. Cl. G09G 3/34 (2006.01); G02B 27/01 (2006.01)
CPC G09G 3/3426 (2013.01) [G02B 27/0172 (2013.01); G09G 2320/064 (2013.01)] 16 Claims
OG exemplary drawing
 
1. A device, comprising:
a backlight unit comprising an arrangement of light-emissive elements; and
a driver circuit comprising:
a voltage boost circuit configured to receive a device input voltage and generate a backlight drive voltage; and
a pulse modulation circuit configured to provide a pulse modulation signal having a duty ratio to the voltage boost circuit, comprising:
a digital pulse width modulation controller;
a loop gain adjuster; and
an analog-to-digital converter configured to receive a headroom signal from a headroom processor and to provide a control signal to the loop gain adjuster thereby adjusting the digital pulse width modulation controller, wherein:
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.