公开(公告)号：WO2018212893A1

公开(公告)日：2018-11-22

申请号：PCT/US2018/028127

申请日：2018-04-18

Applicant: APPLE INC.

Inventor： XIE, Yanhui ,  HUSSAIN, Asif ,  CHEN, Jingdong ,  NAVABI-SHIRAZI, Mohammad J.

IPC: G09G3/34

Abstract: Aspects of the subject technology relate to control circuitry for operating light-emitting diodes (LEDs). The control circuitry may include a pulse-width-modulation (PWM) driver for the LEDs and headroom voltage control circuitry. The PWM driver may adjust a rising edge or a trailing edge of the PWM cycles for various LEDs to ensure a headroom voltage detection window for the headroom voltage control circuitry to sample the headroom voltage of those LEDs without being affected by the rising edge of the PWM cycle for LED or the falling edge of the PWM cycle for another LED.

公开(公告)号：WO2019027691A1

公开(公告)日：2019-02-07

申请号：PCT/US2018/042936

申请日：2018-07-19

Applicant: APPLE INC.

Inventor： XIE, Yanhui ,  HUSSAIN, Asif ,  CHEN, Jingdong ,  PANDYA, Manisha P.

IPC: G09G3/34

Abstract: Aspects of the subject technology relate to control circuitry for light-emitting diodes. The control circuitry includes a two-dimensional light-emitting diode (LED) array. The control circuitry may include a single LED array operable by a common driver or multiple LED arrays each operable by a dedicated LED matrix driver. Each matrix driver may receive a synchronization signal from a common controller and may include a programmable phase lock loop (PLL) to synchronize each matrix driver to the synchronization signal. The LED array may include multiple strings of LEDs mounted in series along the string. Each LED in each string may include a bypass switch operable to modify the current through that LED by pulse-width modulation.

公开(公告)号：WO2018236460A1

公开(公告)日：2018-12-27

申请号：PCT/US2018/028026

申请日：2018-04-17

Applicant: APPLE INC.

Inventor： RYOO, Ji Yeoul ,  HUSSAIN, Asif ,  CHEN, Jingdong ,  NAVABI-SHIRAZI, Mohammad J. ,  XIE, Yanhui

IPC: G09G3/34 ,  G09G3/36

Abstract: Aspects of the subject technology relate to display circuitry such as backlight control circuitry for operating parallel strings of light-emitting diodes (LEDs). A voltage supply circuit of the backlight control circuitry provides a common supply voltage to the strings of LEDs. Headroom control circuitry samples a residual voltage at the end of each string, determines a minimum of the residual voltages, and provides feedback, based on the determined minimum voltage, to the voltage supply circuit. A headroom control feedback loop may be provided including sampling lines coupled to the second end of each string of LEDs for sampling a residual voltage of each string. Headroom control circuitry may modify the supply voltage based on the minimum residual voltage. Sample-and-hold circuitry may be provided that holds the sampled residual voltages until the voltage supply circuit is ready for an update.

公开(公告)号：WO2020068305A1

公开(公告)日：2020-04-02

申请号：PCT/US2019/047408

申请日：2019-08-21

Applicant: APPLE INC.

Inventor： CHEN, Jingdong ,  HUSSAIN, Asif ,  NAVABI-SHIRAZI, Mohammad, J. ,  MOHTASHEMI, Behzad ,  XIE, Yanhui

IPC: H05B33/08 ,  H05B37/03

Abstract: A display may have display layers that form an array of pixels. The array of pixels may be illuminated using a backlight unit. The backlight unit may include multiple strings of light-emitting diodes (LEDs). The multiple LED strings may be controlled by one or more backlight driver integrated circuits (ICs). In a multi-driver IC architecture, an enable signal may be used to set a desired phase delay between the multiple ICs. One or more of the LED strings may exhibit a short fault. Depending on the number of faulty LED strings, the backlight unit can selectively throttle the maximum brightness of the display. The LED strings may receive an output voltage from a DC/DC converter and may be driven using a current driver. The DC/DC converter may be controlled by a headroom feedforward control circuit to ensure sufficient headroom for the current driver while suppressing acoustic noise.

公开(公告)号：WO2019035875A1

公开(公告)日：2019-02-21

申请号：PCT/US2018/000139

申请日：2018-08-15

Applicant: APPLE INC.

Inventor： NAVABI-SHIRAZI, Mohammad, J. ,  ASCORRA, Alejandro, Lara ,  HUSSAIN, Asif ,  RYOO, Ji, Yeoul ,  CHEN, Jingdong ,  QI, Jun ,  PANDYA, Manisha, P. ,  XIE, Yanhui

IPC: G09G3/34 ,  H05B33/08

Abstract: Aspects of the subject technology relate to control circuitry for light-emitting diodes. The control circuitry may operate a light-emitting diode using a multi-peak pulse-width- modulation signal. The control circuitry may include a multi-stage driver having a relatively larger driver stage for providing a direct current through a light-emitting diode and a relatively smaller driver stage configured to cooperate with a pulse-width-modulation controller to pulse-width-modulate a current through the light-emitting diode.