Variable Resistor Backlight Driver for LED Voltage Drop Compensation
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Solution Overview
Problem
The existing backlight driver ICs for LED-based backlight modules face increased power consumption and heat generation due to variations in voltage drops across LEDs, leading to reduced power efficiency.
Innovation Solution
Incorporating a series of resistive elements with variable resistance values connected to each LED chain, where resistive elements with lower resistance values are connected to LED chains with larger voltage drops and higher resistance values are connected to those with smaller voltage drops, dispersing power waste from the backlight driver IC to these elements, and using a power supply circuit to provide the necessary voltage to the LED chain with the largest voltage drop.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If a plurality of LEDs are connected in series to form LED chains and driven by a single backlight driver IC, then the device structure is simplified and power consumption is reduced, but voltage drop variations among LEDs cause increased power consumption and heat generation in the backlight driver IC
Solution Approach 1:
The patent divides the LED chains into multiple parallel groups, with each group containing series-connected LEDs. A separate protective transistor is assigned to each group, allowing independent control and compensation for voltage drop variations in each segment. This segmentation enables the system to handle voltage inconsistencies without increasing overall power consumption in the driver IC.
Solution Approach 2:
The patent introduces protective transistors as intermediary components between the power supply and LED chains. These transistors act as mediators that compensate for voltage drop variations by dynamically adjusting current flow to each LED group, thereby preventing excessive power consumption and heat generation in the backlight driver IC while maintaining stable operation.
2Temperature
If protective transistors are connected in series to each LED chain to limit input voltage, then heat generation in the backlight driver IC is suppressed, but power consumption increases due to the ON resistance of the protective transistors
Solution Approach 1:
The patent applies protective transistors selectively to specific LED chains or groups rather than uniformly to all chains. By identifying which LED chains require protection based on their voltage drop characteristics, the system provides localized compensation only where needed, minimizing the overall power consumption associated with protective transistor ON resistance while still effectively controlling heat generation in the driver IC.
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 configuration reduces power consumption and heat generation in the backlight driver IC by dispersing wasted power to external resistive elements, thereby enhancing power efficiency and minimizing the impact of ON resistance from protective transistors.
Implementation Method 1
the plurality of resistive elements are each connected in series to one of an anode terminal of an LED light source at a first stage and a cathode terminal of an LED light source at a last stage of each of the plurality of LED chains... the plurality of series circuits formed of the plurality of LED chains and the plurality of resistive elements are each connected, on a last stage side thereof, to a drain terminal of each of the plurality of FET switches
Data Source
AI summary
A resistive element is connected in series to a cathode terminal of an LED light source at a last stage (or an anode terminal of an LED light source at a first stage) of an LED chain, and a resistance value of the resistive element is configured to be variable in resistance value in accordance with a variation of voltage drops of the LEDs connected in series so that a resistance value of a resistive element connected to an LED chain having a large voltage drop has a smaller resistance value then a resistance value of a resistive element connected to an LED chain having a small voltage drop. With this configuration, the power, which has been wasted otherwise as heat in the backlight driver IC, may be dispersed to the resistive elements.