Recycling backlights with semi-specular components

US8608363B2 · kind B2 · utility

Assignee

• 3M INNOVATIVE PROPERTIES COMPANY · US

Inventors

• Michael F. Weber · Shoreview, US
• Timothy J. Nevitt · Red Wing, US
• John A. Wheatley · Stillwater, US
• Rolf W. Biernath · Wyoming, US
• David G. Freier · Windom, US
• Gilles J. Benoit · Minneapolis, US
• Charles D. Hoyle · Stillwater, US
• Andrew J. Ouderkirk · Windom, US
• Zhachui Yang · North Oaks, US

Key dates

• Filing date: May 19, 2008
• Grant date: Dec 17, 2013
• Expiry date: May 21, 2030

Classification

• Technology area (CPC G): Physics
• CPC primary: G02F1/13362
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

A hollow light-recycling backlight has a “semi-specular” component providing a balance of specularly and diffusely reflected light improving the uniformity of the light output. The component may be arranged on the reflectors (1021), (1014) or inside the cavity (1016). This balance is achieved by designing the component's “transport ratio” defined by (F−B)/(F+B), (F and B are the amounts of incident light scattered forwards and backwards respectively by the component in the plane of the cavity) to lie in a certain range. Furthermore, the product of the front and back reflector “hemispherical” reflectivities should also lie in a given range. Alternatively, the “cavity transport value”, a measure of how well the cavity can spread injected light from the injection point to distant points in the cavity should lie in a further range and the “hemispherical” reflectivity of the back reflector should be >0.7.