Adaptive Headroom Voltage Control for LED Backlight Power Supply
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Solution Overview
Problem
Existing electronic device displays face challenges in dynamically adjusting headroom voltage for backlight units on a frame-by-frame basis due to settling time constraints, leading to potential power loss from unnecessarily high voltages.
Innovation Solution
Implementing a feedforward coarse tuning and feedback fine tuning mechanism for LED headroom voltage control, based on maximum zone current, maximum row current, and maximum row-to-row current step, to adjust headroom voltage dynamically and efficiently for power saving.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If headroom voltage is maintained at high levels to ensure sufficient power for backlight LEDs, then reliability of display operation is improved, but energy consumption increases and power loss occurs
Solution Approach 1:
The patent implements dynamic headroom voltage adjustment that adapts the voltage level based on real-time display content requirements. The system transitions from static high voltage maintenance to dynamic voltage modulation, adjusting headroom voltage frame-by-frame based on calculated maximum zone currents and row currents. This resolves the contradiction by maintaining reliability only when necessary while reducing power loss during normal operation.
Solution Approach 2:
The system changes the headroom voltage parameter dynamically based on display content analysis. By calculating required currents for upcoming frames and adjusting headroom voltage accordingly, the system optimizes the voltage parameter to match actual needs. This resolves the contradiction between maintaining sufficient power (reliability) and minimizing unnecessary power consumption (energy loss).
2Loss of energy
If headroom voltage is adjusted dynamically on a frame-by-frame basis, then energy efficiency is improved, but system complexity increases due to settling time constraints
Solution Approach 1:
The patent applies preliminary action by calculating the required headroom voltage for the upcoming frame during the current frame's processing. The system determines maximum zone currents and row currents in advance, allowing the power supply to be programmed with the appropriate headroom voltage before the next frame begins. This advance preparation reduces the impact of settling time constraints while maintaining energy efficiency.
Solution Approach 2:
The system implements feedback mechanisms by monitoring actual current consumption and comparing it with predicted requirements. The feedback loop allows the system to refine its headroom voltage predictions and adjust control parameters accordingly. This feedback approach manages system complexity by using measured data to simplify future control decisions while maintaining energy efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for frame-by-frame headroom control, ensuring sufficient power to backlight LEDs while minimizing power loss by adjusting headroom voltage based on real-time current requirements, thereby optimizing power usage.
Implementation Method 1
The backlight unit commonly includes one or more light-emitting diodes (LEDs) that generate light
Data Source
AI summary
Aspects of the subject technology relate to control circuitry for light-emitting diodes. The control circuitry may include feedforward control and a feedback control for a power supply for the light-emitting diodes. The feedforward control may include host circuitry for the device that determines a maximum zone current, a maximum row current, and the maximum row-to-row current step for an upcoming backlight frame while a current backlight frame is being executed. A headroom voltage for the upcoming backlight frame is determined based on the maximum zone current, the maximum row current, and/or the maximum row-to-row current step and provided to the power supply so that the power supply can settle at a corresponding supply voltage before the upcoming backlight frame is executed. The feedback control utilizes dynamic thresholds determined for each backlight frame to fine tune the feedforward-determined headroom voltage.