Filing activity in this space is concentrated among a small group of large electronics and materials manufacturers, with the ranking table on this page showing exactly where each assignee sits by family count. The historically largest filers show sharply reduced or zero activity in the most recent year, which suggests the leading positions were established earlier rather than being actively contested today. Newer entrants tend to file in smaller volumes around adjacent uses such as lighting integration or adhesive chemistry rather than the core brightness-enhancement or polarizer constructions.

A brightness enhancement film is a microstructured optical film placed in a display's backlight stack to redirect light toward the viewer and increase apparent brightness without adding power. The two most-cited records in this dataset, US6111696A and US5917664A, are foundational brightness-enhancement film patents with hundreds of citations each, meaning most later filings in this technology area had to build on, license around, or explicitly distinguish their claims. High citation counts here reflect long-standing influence on the field rather than current filing activity, since older records accumulate citations simply by having been available longer.

The smaller IPC subclasses in this dataset — lighting-device integration, signage/display formats, and polymer processing chemistry for film substrates — carry far fewer filings than the dominant optical-element and optical-control categories. That gap does not mean the technology is unclaimed everywhere; it means the specific combination of film chemistry with those integration contexts is thinner ground than the base film constructions. A first filing there is more defensible if it ties a specific adhesive or retardation chemistry to a measurable durability or viewing-angle outcome under a defined integration constraint.

Patent applications are typically published around 18 months after they are filed, so any dataset's most recent one to two years will always look thinner than they eventually turn out to be. In this dataset the decline is visible from the 2019 peak of 32 filings through a 2022 midpoint of 19 down to the partial final year, and only part of that later decline is a publication-lag artifact rather than an actual drop in filing activity. Anyone using this trend to judge current R&D investment should treat the last two years as provisional.

The United States leads this dataset's receiving offices with 200 records, followed by China at 145 and South Korea at 66, with the European Patent Office, WIPO/PCT and Taiwan trailing behind. That distribution reflects where the largest display-panel manufacturing and consumer-electronics markets sit, and where enforcement risk is most likely to concentrate for anyone shipping finished panels or films into those jurisdictions. Filing in a single office without a matching PCT or regional filing can leave meaningful gaps in geographic coverage for a technology this globally manufactured.

US20090251642A1 is assigned to Dai Nippon Printing and claims a retardation film built from an optical anisotropic film paired with a retardation layer containing a liquid-crystalline material, defined through two specific refractive-index relationships. It is used as a polarizing plate protective film and is designed to deliver both durability and viewing-angle compensation in a single film stack. Anyone designing a polarizer protective film with a similar dual-layer, defined-refractive-index construction should check this record's full claim scope and priority date before proceeding.