Film Lightguide Edge Cutting for Thin Flexible Backlights

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Solution Overview

Problem

Existing light emitting devices, such as displays and backlights, have a thick form factor due to rigid lightguides that limit design flexibility and require long lead times for design changes, and they struggle to couple sufficient light flux into thinner lightguides.

Innovation Solution

A film-based lightguide with linear light turning features oriented in the web direction and cut at specific angles to define lateral edges, allowing for a thickness less than 0.5 millimeters, combined with a layer of adhesive and linear light turning features, to create a flexible and efficient light emitting device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If rigid lightguides are used to reduce display thickness, then light guidance function is improved, but device flexibility and design adaptability deteriorate

Engineering Contradiction:

Improvedisplay thicknessVSAvoiddesign flexibility

Core Design Contradiction:

Length of moving objectVSAdaptability or versatility

Solution Approach 1:

The patent replaces rigid lightguide blocks with flexible film-based lightguides that can be laminated onto display surfaces. These thin film lightguides maintain effective light guidance functionality while enabling device flexibility and adaptable design configurations, directly resolving the contradiction between thickness reduction and design versatility.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The invention changes the physical state and material parameters of the lightguide from rigid bulk material to flexible thin film with specific optical properties. By modifying the refractive index profile and structural parameters of the film, the lightguide maintains its light guidance capability while achieving the desired flexibility and thinness.

Inventive Principle:

Principle #35Parameter changes

2Volume of moving object

If lightguide thickness is reduced to improve device profile, then device volume is reduced, but light coupling efficiency deteriorates

Engineering Contradiction:

Improvedevice volumeVSAvoidlight coupling efficiency

Core Design Contradiction:

Volume of moving objectVSReliability

Solution Approach 1:

The patent implements localized optical features within the thin film lightguide, including varying refractive index regions and structured surfaces at specific locations. These local modifications enable effective light coupling and distribution throughout the thin structure, maintaining light guidance reliability despite the reduced overall thickness.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The invention uses composite film structures with multiple layers having different optical properties, including core and cladding layers with specific refractive index differences. This composite structure enables efficient light coupling and confinement within the thin film, resolving the contradiction between reduced volume and maintained coupling efficiency.

Inventive Principle:

Principle #40Composite materials

3Reliability

If conventional lightguide manufacturing is used to ensure structural integrity, then manufacturing reliability is improved, but production time and complexity increase

Engineering Contradiction:

Improvestructural integrityVSAvoidproduction speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent replaces complex mechanical machining and assembly processes with lamination and bonding techniques. The film-based lightguide is applied to the display surface through lamination, eliminating the need for precise mechanical cutting and assembly of rigid components, thereby improving production speed while maintaining structural integrity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention prepares the lightguide film with pre-formed optical features and structures before lamination. This preliminary preparation includes creating the refractive index profile and surface structures in advance, which simplifies the final assembly process and ensures structural integrity without requiring complex post-assembly operations.

Inventive Principle:

Principle #10Preliminary action

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 thinner light emitting devices with improved design flexibility and efficient light coupling, reducing thickness and volume while maintaining effective light output.

Implementation Method 1

edge-lit configurations using rigid lightguides have been used to receive light from the edge of and direct light out of a larger area surface

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS12571956B2Manufacturing a lightguide with cut lateral edges

Publication Date: 2026.03.10 AZUMO INC

AI summary

A method of manufacturing a film assembly comprises forming a film-based lightguide with a lightguide region, adding a layer comprising linear light turning features to the film-based lightguide while it is moving in a web direction such that the linear light turning features are oriented in the web direction of the film-based lightguide, and cutting the film-based lightguide while it is moving in a web direction in a plurality of linear sections, the plurality of linear sections comprises linear sections that define lateral edges a light emitting region and/or lateral edges of coupling lightguides extending from the lightguide region, wherein the linear sections are cut at first cut angle between 3 degrees and 25 degrees to a transverse direction of the film-based lightguide orthogonal to the web direction and the thickness direction.