MJT LED Backlight Module Low Current Operation

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Solution Overview

Problem

Existing backlight units using single-cell LEDs face challenges with high current operation, leading to increased power consumption, manufacturing costs, and reduced stability and reliability due to the need for large capacity electronic devices and dense LED arrangements, which also result in uneven screen illumination and a droop phenomenon.

Innovation Solution

The use of multi-junction technology (MJT) LEDs with multiple light emitting cells connected in series, operated at low current, and a backlight unit design that includes optical members to enhance light distribution, allowing independent control of each MJT LED and reducing the number of LEDs required.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If single-cell LEDs are used with high current operation, then sufficient light output is achieved, but power consumption increases and stability deteriorates

Engineering Contradiction:

Improvepower consumptionVSAvoidstability and reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent divides a single high-current LED into multiple low-current LEDs connected in series. Each LED operates at a lower current (e.g., 30-50mA instead of 100mA+), which improves stability and reliability while maintaining sufficient total light output. This segmentation also allows independent control of each LED, further enhancing system reliability.

Inventive Principle:

Principle #1Segmentation

2Illumination intensity

If the number of LEDs is increased to improve illumination coverage, then uniform screen illumination is achieved, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improveuniform screen illuminationVSAvoidnumber of LEDs and drive circuits

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent introduces optical members (lenses, reflectors, diffusers) to manipulate light distribution in additional spatial dimensions. These optical components redirect and diffuse light from fewer LEDs to achieve uniform illumination across the screen, eliminating the need to increase LED quantity and thereby reducing device complexity.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Area of stationary object

If LEDs are densely arranged to cover larger area, then illumination coverage is improved, but manufacturing cost and device complexity increase

Engineering Contradiction:

Improveillumination coverage areaVSAvoidmanufacturing cost

Core Design Contradiction:

Area of stationary objectVSEase of manufacture

Solution Approach 1:

The patent introduces optical members as intermediary components between the LEDs and the illumination area. These optical members (lenses, reflectors, diffusers) extend the effective illumination range of each LED, allowing fewer LEDs to cover larger areas without dense arrangement, thereby reducing manufacturing cost and complexity.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Illumination intensity

If high current is supplied to LEDs, then sufficient light output is achieved, but droop phenomenon occurs and efficiency decreases

Engineering Contradiction:

Improvelight outputVSAvoiddroop phenomenon and efficiency

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The patent segments the light output requirement across multiple LEDs operating at low current. By connecting LEDs in series and operating each at 30-50mA instead of high current, the system achieves sufficient total light output while avoiding the droop phenomenon that occurs at high current, thereby maintaining high energy efficiency.

Inventive Principle:

Principle #1Segmentation

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 enables low current operation of the backlight module, improving stability and reliability of drive circuits, reducing manufacturing costs, and enhancing power efficiency while preventing the droop phenomenon and achieving uniform illumination.

Implementation Method 1

multi junction technology (MJT) light emitting diode (LED)... each of the MJT LEDs includes a first light emitting cell and a second light emitting cell... connected in series

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Implementation Method 2

optical members... each including a light incident face through which light emitted from the corresponding MJT LED enters the optical member and a light exit face through which light exits the optical member at a wider beam angle

Methodology Applied

Scientific EffectLight refraction and reflection: Refraction

Implementation Method 3

optical members... to enhance light distribution

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS10292216B2Backlight module with MJT LED and backlight unit including the same

Publication Date: 2019.05.14 SEOUL SEMICONDUCTOR

AI summary

A backlight unit including a backlight module and a backlight control module. The backlight module includes a printed circuit board including blocks arranged in an M×N matrix, in which M and N are natural numbers of 2 or greater, and M blocks are arranged in a horizontal direction and N blocks are arranged in a vertical direction, and at least one light emitting device disposed on each of the blocks. The backlight control module is configured to perform a dimming control of the M×N blocks such that the at least one light emitting device in one block can be controlled independently from other light emitting devices disposed in the remaining blocks that are disposed in the horizontal direction and in the vertical direction with respect to the one block.