LED Backlight Current Mirror Circuit for LCD Brightness and Power Trade-off
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Solution Overview
Problem
Large LCD devices with high brightness requirements face increased costs and power consumption due to the need for numerous LEDs and driving ICs, leading to reduced display quality and contrast ratios.
Innovation Solution
The implementation of a liquid crystal display device with a matrix of LEDs, each driven by a separate LED unit comprising a switching circuit and a current mirror circuit, allowing for independent control of brightness and reducing the number of required driving ICs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the number of LEDs is increased to achieve high brightness, then the brightness is improved, but the power consumption increases
Solution Approach 1:
The patent divides the backlight into multiple LED blocks, each independently controllable. This segmentation allows selective activation of only the necessary number of LED blocks to achieve required brightness levels, thereby reducing overall power consumption while maintaining the ability to provide high brightness when needed.
Solution Approach 2:
The patent implements dynamic control of LED blocks through independent driving circuits for each block. This dynamic capability enables the system to adjust the number of active LED blocks based on real-time brightness requirements, optimizing the balance between illumination intensity and power consumption.
2Productivity
If the number of driving ICs is increased to drive more LED blocks, then the capability to drive LEDs is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple driving functions into a single integrated driving circuit that can control multiple LED blocks. This merging approach eliminates the need for separate driving ICs for each LED block, reducing device complexity while maintaining the capability to drive a large number of LEDs.
Solution Approach 2:
The driving circuit is designed with multi-functional capabilities to control different numbers and configurations of LED blocks. This universal design allows a single driving IC to adapt to various backlight configurations, improving driving capability without proportionally increasing device complexity.
3Device complexity
If LEDs in each block are driven in common by the same constant-current source circuit, then the device complexity is reduced, but the contrast ratio is limited and display quality is reduced
Solution Approach 1:
The patent assigns separate constant-current source circuits to each LED block, enabling independent current control for each block. This segmentation allows precise control of light emission from each block, improving contrast ratio by enabling darker regions while maintaining simpler overall circuit architecture through modular design.
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 solution improves display quality by enhancing contrast ratios and reducing power consumption while minimizing the number of circuit components, thereby lowering costs.
Implementation Method 1
an LED that emits the light in response to the light emission current
Data Source
AI summary
A liquid crystal display device includes a liquid crystal panel; a plurality of light emitting diode units to supply light to the liquid crystal panel; and a scan line and a light emission data line connected to the LED unit, wherein the scan line and the light emission data line transfer a scan signal and a light emission data current, respectively, wherein the LED unit includes: a switching circuit that is connected to the scan line and the light emission data line; a current mirror circuit that is connected to the switching circuit, and that outputs a light emission current in response to the light emission data current; and an LED that emits the light in response to the light emission current.