US 5919551

Patent Overview — US 5,919,551 A

Title: Variable pitch structured optical film

Assignee/Current Assignee (per listing): 3M Innovative Properties Co; also listed as 3M Co. Original assignee: 3M Innovative Properties Co. Inventors: Sanford Cobb, Jr.; Mark E. Gardiner; Keith M. Kotchick; Kazuhiko Toyooka; William A. Hibbard.

Key dates: Priority/filing date 1996-04-12; publication/grant 1999-07-06; anticipated expiration 2016-04-12. Legal status listed as "Expired - Lifetime." A 1996-07-01 assignment to Minnesota Mining and Manufacturing Company is recorded.

Purpose: Structured optical films are used in optical display systems to control light direction (transmitted/reflected) to increase brightness and reduce glare. Using two such films, with prisms angled (typically about 90°), can increase brightness within a narrowed viewing range but may worsen moire interference and cause optical coupling—uneven transmission appearing as bright spots, streaks, or lines where a plano surface contacts or nearly contacts a structured surface.

Plain-language scope: The invention is a structured optical film whose structured surface has generally parallel peaks separated by valleys, arranged in groups where adjacent-group pitch differs. One aspect: a first group of adjacent peaks with a first peak pitch, and an adjacent second group with a different second peak pitch. Another aspect applies the same group-to-group pitch variation to valleys separated by peaks. A further aspect: peak pitch is substantially constant while valley pitch varies within a group of three or more successive adjacent valleys. Preferred group size is 20 or fewer adjacent peaks/valleys (more preferably 10 or fewer; even more preferably 3 or fewer). Groups may be defined by width—about 0.5 mm or less, more preferably about 200 µm or less. It is also preferable that pitch varies over any three adjacent valleys/peaks. The stated aim is reducing visibility of moire interference patterns.

Source: https://patents.google.com/patent/US5919551/en

What the excerpt does not establish: Claims are not fully reproduced; the excerpt also does not provide the complete specification, drawings, examples, or the exact claim language/claim count. It does not establish validity, enforceability, litigation, or ownership transfers beyond the recorded assignment.