IP Verse

Optical Stack And Lightguides

Patent No. US2013022315 (titled "Optical Stack And Lightguides") was filed by Edmonds William F on Apr 11, 2011. The application was issued on Jan 24, 2013.

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Technical Landscape

In the early 2010s when ’315 was filed, flat panel display architectures typically relied on discrete layers of prismatic light-directing films and reflective polarizers to manage brightness and viewing angles. At a time when optical stacks were typically implemented using mechanical clamping or thick adhesive layers to maintain structural integrity, achieving high peel strength between layers while preserving optical performance was non-trivial. When systems commonly relied on air gaps or low-refractive-index coatings to facilitate total internal reflection within lightguides, the physical integration of these layers often introduced thickness penalties or compromised the precise geometry of microstructured surfaces required for efficient light extraction.

Prosecution Position

The disclosed invention represents a technical advancement through an architectural shift in how microstructured light-directing films are integrated into multi-layer optical stacks. By utilizing a specific structural configuration where unitary discrete structures penetrate into an adhesive layer with a high aspect ratio—specifically where the ratio of average penetration depth to average minimum penetration base dimension is at least 1.5—the stack achieves a peel strength exceeding 30 grams/inch without significant loss in optical transmission. This integration overcomes the technical constraint of balancing mechanical durability with optical efficiency, as the controlled penetration allows for a robust physical bond while minimizing the contact area that would otherwise frustrate total internal reflection or degrade the prismatic effect of the light-directing film.

Claims

The patent contains a total of 18 claims, with claims 1, 11, and 25 serving as the independent claims. These independent claims focus on the configuration of an optical stack featuring a low index layer with voids and a light directing film with discrete structures that penetrate into an adhesive layer at specific depth-to-width ratios to ensure high peel strength and specific light transmission properties. The dependent claims serve to further define the physical characteristics of the stack, such as the refractive index, thickness, and haze of the low index layer, the specific geometry and contact area of the discrete structures, and the integration of the stack into an illumination system with a lightguide.

Key Claim Terms New

Definitions of key terms used in the patent claims.

Term (Source)	Support for Specification	Interpretation
Low index layer (Claim 11, Claim 25)	In some cases, the effective index of refraction of the low index layer is not greater than about 1.3, or about 1.25, or about 1.2, or about 1.15, or about 1.05. The low index layer includes a plurality of voids that are dispersed in a binder. In some cases, the low index layer include a plurality of interconnected voids that are dispersed in a binder.	A layer having a reduced effective refractive index, typically not greater than 1.3, achieved through a plurality of voids (such as interconnected voids) dispersed within a binder material.
Minimum penetration base dimension (Claim 11, Claim 25)	The penetration base has a minimum penetration base dimension. In some cases, the average minimum penetration base dimension is less than about 10%, or about 8%, or about 6%, or about 5%, or about 4%, or about 3%, of the average minimum base dimension.	The smallest lateral width or diameter of the unitary discrete structure measured at the point where it enters the optical adhesive layer.
Penetration base (Claim 11, Claim 25)	Each unitary discrete structure defines a penetration depth and a penetration base at the interface between the penetrating and non-penetrating portions of the unitary discrete structure. The penetration base has a minimum penetration base dimension. The plurality of unitary discrete structures has an average penetration depth and an average minimum penetration base dimension.	The specific interface or cross-sectional area of a unitary discrete structure located exactly at the boundary between the portion embedded in an adhesive and the portion remaining outside the adhesive.
Reflective polarizer layer (Claim 11)	The reflective polarizer layer substantially reflects light of a first polarization state and substantially transmits light of a second polarization state orthogonal to the first polarization state. In some cases, the first optical stack further includes a light diffusing layer that is disposed on the reflective polarizer layer.	An optical film that manages light by reflecting one polarization state while transmitting the orthogonal polarization state to enhance display efficiency.
Unitary discrete structures (Claim 11, Claim 25)	The light directing film is disposed on the low index layer and includes a plurality of unitary discrete structures. Portions of each unitary discrete structure penetrate into the first optical adhesive layer. Portions of each unitary discrete structure do not penetrate into the first optical adhesive layer.	Individual, distinct structural elements (such as microstructures or prisms) that are part of a light directing film and are capable of penetrating an adhesive layer to provide mechanical bonding.

Patent Summary

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US2013022315

EDMONDS WILLIAM F

Application Number: US201113634583
Filing Date: Apr 11, 2011
Publication Date: Jan 24, 2013
External Links: Slate, USPTO , Google Patents