Backlight Headroom Control for LED Power Optimization
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Solution Overview
Problem
Current electronic devices with displays, particularly those using liquid crystal displays (LCDs) and organic light-emitting diode (OLED) displays, face inefficiencies in power consumption due to constant backlight operation, leading to undesirable power dissipation, especially in portable devices, as they provide a headroom voltage to ensure operation of all LEDs, which can result in unused power being wasted as heat.
Innovation Solution
The implementation of headroom control circuitry in the backlight unit, which dynamically adjusts the supply voltage to minimize the headroom voltage required, using feedback loops and voltage tracking to ensure sufficient voltage for all LEDs while reducing energy loss by sampling residual voltages and adjusting the target voltage for the switching regulator, thereby optimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed headroom voltage is provided to ensure operation of all LEDs, then reliability of backlight operation is improved, but power consumption increases due to unused power being wasted as heat
Solution Approach 1:
The patent implements dynamic headroom control by continuously monitoring the actual voltage requirements of LED strings and adjusting the supplied headroom voltage in real-time. The system transitions from a static fixed voltage approach to a dynamic adaptive approach, where the headroom voltage is modified based on actual operating conditions such as temperature, LED aging, and current draw variations, thereby eliminating wasted power while ensuring reliable operation.
Solution Approach 2:
The patent employs feedback mechanisms where the system monitors the actual voltage at the LED string terminals and compares it against the supplied headroom voltage. This feedback loop enables the system to detect when the fixed headroom voltage is excessive and automatically reduce it to the minimum necessary level, preventing power waste while maintaining reliable LED operation.
2Use of energy by moving object
If dynamic voltage adjustment is implemented to reduce power consumption, then energy efficiency is improved, but device complexity increases due to additional control circuitry
Solution Approach 1:
The patent designs the voltage control circuitry to serve multiple functions: it provides headroom voltage generation, monitors LED string voltage, detects operating conditions (temperature, aging), and dynamically adjusts the voltage supply. By making the control circuitry multi-functional, the patent reduces the need for separate dedicated components for each function, thereby limiting the increase in device complexity while achieving dynamic power optimization.
Solution Approach 2:
The system performs self-adjustment by automatically monitoring its own operating conditions and voltage requirements without external intervention. The control circuitry uses internal sensors and feedback signals to autonomously determine the optimal headroom voltage, eliminating the need for complex external control systems or manual calibration procedures.
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 reduces power consumption by minimizing unnecessary power dissipation, enhancing the efficiency of display backlight units and extending battery life in portable devices by dynamically managing the supply voltage based on actual LED requirements.
Implementation Method 1
headroom control circuitry configured to sample a residual voltage for each of at least two of the light-emitting diodes, determine a minimum of the residual voltages, and provide a supply voltage modification to the voltage supply circuit based on the determined minimum of the residual voltages
Data Source
AI summary
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.