Optical coupling in touch-sensing systems

US9785287B2 · kind B2 · utility

Assignee

• FlatFrog Laboratories AB · SE

Inventors

• Håkan Bergström · Staffanstorp, SE
• Ola Wassvik · Ryssby, SE
• Thomas Craven-Bartle · Lund, SE
• Olov Von Hofsten · Stockholm, SE
• Björn Magnus Jacobsson Le Normand · Stockholm, SE
• Leif Ek · Stuvsta-Snättringe, SE

Key dates

• Filing date: Dec 17, 2013
• Grant date: Oct 10, 2017
• Expiry date: Dec 19, 2033

Classification

• Technology area (CPC G): Physics
• CPC primary: G06F2203/04109
• WIPO field: Electrical machinery, apparatus, energy
• WIPO sector: Electrical engineering

Abstract

A touch-sensitive aparatus operates by light frustration (FTIR) and comprises a light transmissive panel (1) with a front surface (5) and a rear surface (6). Light emitters (2) are optically coupled to the panel (1) at entry ports along a periphery region of the panel (1), and light detectors (3) are optically coupled to the panel (1) at exit ports along the periphery region for detecting light transmitted inside the panel (1). At least one optical sheet (20) is provided on the rear surface (6) in the periphery region. In an outcoupling installation, the light detectors (3) are arranged at the respective optical sheet (20) to receive, on a respective light-sensitive surface (3A); light from the optical sheet (20), and each light detector (3) is arranged with the light-sensitive surface (3A) essentially perpendicular to the rear surface (6). In an incoupling installation, each light emitter (2) is arranged at the respective optical sheet (20) to emit diverging light with a main direction that is essentially parallel to the rear surface (6) such that a portion of the diverging light impinges on the optical sheet (20) so as to define a respective entry port.