Backlight Unit With Cavity-Integrated LED Chips

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Solution Overview

Problem

Conventional backlight units face limitations in thickness reduction and local dimming capabilities, with edge type units restricted by LED chip placement and direct type units limited by thickness and individual operation of LED chips, while also experiencing inefficiencies in light distribution due to separation distances between light diffusing members and LED chips.

Innovation Solution

A backlight unit design featuring a circuit board with light emitting diode chips mounted on it, surrounded by reflective members and a light diffusing member with cavities to house the LED chips, allowing for thickness reduction and local dimming capabilities, and improving light extraction efficiency through optimized light distribution using reflective and diffusing structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If light sources are disposed at a side of a light diffusing member (edge type), then the structure is compact, but thickness reduction of the bezel is limited and individual operation of LED chips is not enabled

Engineering Contradiction:

Improvestructure compactnessVSAvoidbezel thickness

Core Design Contradiction:

Device complexityVSLength of stationary object

Solution Approach 1:

The patent transitions from edge-type lateral arrangement to direct-type vertical arrangement of LED chips relative to the light diffusing member, changing the spatial dimension of light source placement. This enables thickness reduction in the vertical direction while maintaining compactness through integrated cavity design.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The light diffusing member is divided into multiple cavities that can independently house individual LED chips, enabling segmented control and individual operation of each light source. This segmentation allows for local dimming capabilities while maintaining overall compactness.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If light sources are disposed under the light diffusing member (direct type), then individual operation of LED chips is enabled, but thickness reduction of the backlight unit is limited

Engineering Contradiction:

Improveindividual LED chip operationVSAvoidbacklight unit thickness

Core Design Contradiction:

Adaptability or versatilityVSLength of stationary object

Solution Approach 1:

LED chips are nested within cavities formed in the light diffusing member itself, integrating the light source housing into the diffusing structure. This nesting eliminates separate mounting spaces and reduces overall backlight unit thickness while maintaining individual LED control capabilities.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent merges the functions of the light source holder and the light diffusing member into a single integrated structure. The cavities in the light diffusing member serve both as mounting structures for LED chips and as the diffusing element itself, reducing component count and thickness.

Inventive Principle:

Principle #5Merging (Combining)

3Loss of energy

If distance between light diffusing member and light emitting diode chip is reduced, then luminous efficacy is improved, but uniform light distribution becomes difficult to achieve

Engineering Contradiction:

Improveluminous efficacyVSAvoidlight distribution uniformity

Core Design Contradiction:

Loss of energyVSManufacturing precision

Solution Approach 1:

The light diffusing member features cavities with specific local geometries designed to optimize light extraction and distribution. Each cavity's shape and position are locally optimized to ensure uniform light distribution while maintaining minimal distance between LED chips and the diffusing surface, thereby improving luminous efficacy without sacrificing uniformity.

Inventive Principle:

Principle #3Local quality

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

The solution enables significant thickness reduction and local dimming of display devices while ensuring uniform light emission and minimizing dark spots, enhancing the overall light extraction efficiency and uniformity of the backlight unit.

Implementation Method 1

The reflective members are stacked and reflect some fraction of light emitted through an upper surface of the light emitting diode chip

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 2

a light diffusing member having a light incident surface on which light is incident and a light exit surface through which light is emitted

Methodology Applied

Scientific EffectLight diffusion: Scattering

Data Source

PatentUS11598509B2Backlight unit

Publication Date: 2023.03.07 SEOUL SEMICONDUCTOR

AI summary

The present invention relates to a backlight unit for use in a display device. The backlight unit includes a circuit board, at least one light-emitting diode chip mounted on the circuit board, a plurality of reflection members arranged on the upper part of the light-emitting diode chip, and a light diffusing member. The light diffusing member has an incident surface on which light enters and an emitting surface from which light is emitted. The light diffusing member is arranged on the upper part of the circuit board. The plurality of reflection members are stacked on each other and reflect a part of light emitted from the upper surface of the light-emitting diode chip.