Optical coupling in touch-sensing systems

• Main Authors: Ek Leif, Bergstrom Hakan, Wassvik Ola, Craven-Bartle Thomas, Le Normand Bjorn, Von Hofsten Olov
• Format: Patent
• Language: English
• Published: 10.10.2017
• Subjects: BLASTING; CALCULATING; COMPUTING; COUNTING; ELECTRIC DIGITAL DATA PROCESSING; FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMSTHEREOF; HEATING; LIGHTING; MECHANICAL ENGINEERING; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHYSICS; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHERARTICLES, NOT OTHERWISE PROVIDED FOR; WEAPONS

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.