Backlight Unit Series-Parallel LED Circuit for Uniform Brightness
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Solution Overview
Problem
Existing liquid crystal display devices using edge-type LED backlights suffer from non-uniform brightness due to differences in current flow through LEDs, leading to inadequate light distribution across the display panel, and current mirror circuits proposed as a solution increase device costs.
Innovation Solution
A backlight unit design where (2i−1)th LEDs are connected in a first series circuit and 2ith LEDs are connected in a second series circuit, with each 2ith LED disposed adjacent to a respective (2i−1)th LED, creating a series-parallel configuration to ensure uniform light distribution without the need for additional current equalizing devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If LEDs are connected in a simple series or parallel configuration, then the circuit is simple to manufacture, but the light distribution becomes non-uniform due to current flow differences
Solution Approach 1:
The LED array is segmented into multiple series circuits that are connected in parallel. Each series circuit contains multiple LEDs connected in series, and these series circuits are then connected in parallel to each other. This segmentation allows current to be distributed more evenly across all LEDs, solving the non-uniform light distribution problem while maintaining manufacturing simplicity.
2Illumination intensity
If current mirror circuits are used to equalize current flow through LEDs, then light distribution uniformity is improved, but device complexity and cost increase
Solution Approach 1:
The invention extracts and eliminates the need for complex current mirror circuits by using a simpler series-parallel LED connection configuration. The current equalization function is achieved through the circuit topology itself rather than through additional active components, thereby reducing device complexity and cost while maintaining uniform light distribution.
3Device complexity
If LEDs are arranged in a single series circuit, then the circuit structure is simple, but current flow differences cause non-uniform brightness across the display
Solution Approach 1:
The single series circuit is segmented into multiple series circuits that are connected in parallel. This segmentation creates multiple current paths, allowing current to be distributed more evenly across all LEDs. The result is improved brightness uniformity while the overall circuit structure remains relatively simple and easy to manufacture.
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 achieves uniform light intensity across the liquid crystal display panel, reducing costs associated with current mirror circuits while maintaining even brightness distribution.
Implementation Method 1
a plurality of light emitting diodes, wherein (2i-1)th (where i is a natural number, a natural number being a positive integer) light emitting diodes of the plurality are connected in a first series circuit
Data Source
AI summary
This invention relates to a backlight unit that is adaptive for increasing brightness uniformity, and a liquid crystal module using the same. The backlight unit includes a plurality of light emitting diodes with the (2i−1)th (where i is a natural number) light emitting diodes of the plurality connected in a first series circuit between an input terminal and an output terminal and the 2ith light emitting diodes of the plurality connected in a second series circuit. The second series circuit is connected in parallel with the first series circuit between the input terminal and the output terminal, and each of the 2ith light emitting diodes is disposed adjacent to a respective (2i−1)th light emitting diode.