Reflective PCB Lighting Structure Without a Light Guide Plate

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Solution Overview

Problem

Existing lighting apparatuses face limitations in increasing reflectivity and luminance without increasing thickness or the number of light sources, and they struggle with image quality degradation due to the presence of a light guide plate.

Innovation Solution

A lighting apparatus design that incorporates a reflecting unit with an air area on the printed circuit board, utilizing a reflective film with a patterned bonding material to define air gaps, and replaces the light guide plate with a film-type resin layer to guide light sources, enhancing reflectivity and luminance while reducing thickness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a light guide plate is used to guide light from LEDs, then light distribution is achieved, but the thickness of the lighting apparatus cannot be reduced and image quality decreases in large area applications

Engineering Contradiction:
ImproveluminanceVSAvoidthickness
Core Design Contradiction:
Illumination intensityVSLength of stationary object

Solution Approach 1:

The patent removes the light guide plate from the lighting apparatus structure. Instead of using a light guide plate to distribute light, the invention uses a reflecting unit with an air area directly on the printed circuit board to reflect and distribute light from LEDs, thereby eliminating the thickness constraint imposed by the light guide plate while maintaining light distribution functionality

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an air area dimension in the reflecting unit structure, creating a three-dimensional reflective cavity above the printed circuit board. This vertical air space allows light to be reflected and distributed effectively without requiring a thick light guide plate, thus reducing overall thickness while maintaining illumination performance

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Illumination intensity

If more light sources are added to increase luminance, then brightness improves, but the number of components and thickness increase

Engineering Contradiction:
ImproveluminanceVSAvoidnumber of light sources
Core Design Contradiction:
Illumination intensityVSDevice complexity

Solution Approach 1:

The patent converts the potentially harmful effect of light loss into a beneficial reflection mechanism. By creating a reflecting unit with an air area, the structure captures and reflects light that would otherwise be lost, directing it toward the display panel. This increases luminance without adding more LEDs, as the same light sources are utilized more efficiently through reflection

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent changes the optical parameters of the lighting structure by introducing a reflecting unit with specific air area dimensions and reflective properties. This modification improves light utilization efficiency and luminance output without requiring additional light sources, thereby maintaining device simplicity while achieving higher brightness

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If a light guide plate is used, then light guidance is achieved, but design freedom is limited and the structure becomes more complex

Engineering Contradiction:
Improvedesign freedomVSAvoidstructure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts and removes the light guide plate component from the lighting apparatus. By eliminating this component, the invention simplifies the overall structure and increases design freedom, allowing for more flexible integration into various display configurations without being constrained by the presence of a light guide plate

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The reflecting unit with air area serves multiple functions: it reflects light, distributes illumination, and provides structural support. This multi-functional design replaces the light guide plate's light guidance function while adding reflective capabilities, thereby simplifying the overall structure and enhancing design versatility across different application scenarios

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 achieves improved luminance and reflectivity, reduces the number of light sources, and decreases the overall thickness of the apparatus, ensuring optical uniformity and reliability by using side-type LEDs and a resin layer to guide light, thus enhancing the lighting apparatus's efficiency and flexibility.

Implementation Method 1

a reflecting unit stacked on the printed circuit board, with the LEDs through the reflecting unit, in which the reflective unit includes a reflective film containing metal attached to the surface of the printed circuit board

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

a transparent second reflective film spaced from the first reflective film and defining the air area

Methodology Applied
Scientific EffectTotal Internal Reflection: Total Internal Reflection

Data Source

PatentEP4080275B1Lighting apparatus
Publication Date: 2026.04.29 LG INNOTEK CO LTD
  • EP4080275B1 patent drawingFigure 1~3
  • EP4080275B1 patent drawingFigure 4
  • EP4080275B1 patent drawingFigure 5~6

AI summary

A lighting apparatus comprising a printed circuit board (110), a plurality of light sources (130) disposed on the PCB (110), a reflecting unit (120) disposed on the PCB (110), a resin layer (140) disposed on the reflecting unit (120) to cover the plurality of light sources (130); and an optical pattern layer (150) comprising a first optical layer (150B) disposed on the resin layer (140), a second optical layer (150A) spaced apart from the first optical layer (150B), a plurality of optical patterns (151) and a bonding pattern layer (153) that are disposed between the first optical layer (150B) and the second optical layer (150A), and a second spaced area (152) disposed around the optical patterns (151) and separating the bonding pattern layer (153) from the optical patterns (151).