The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 30, 2019
Filed:
Dec. 17, 2013
Flatfrog Laboratories Ab, Lund, SE;
Thomas Craven-Bartle, Sodra Sandby, SE;
Håkan Bergström, Torna-Hallestad, SE;
Ivan Karlsson, Lund, SE;
Ola Wassvik, Brosarp, SE;
David Sernelius, Malmo, SE;
FlatFrog Laboratories AB, Lund, SE;
Abstract
A touch-sensitive apparatus operates by light frustration (FTIR) and comprises a light transmissive panel () that defines a front surface () and a rear surface (), light emitters optically connected to the panel () so as to generate light that propagates by total internal reflection inside the panel, and light detectors () optically connected to the panel () so as to define a grid of propagation paths inside the panel () between pairs of light emitters and light detectors (). Each light detector () is optically connected to the panel () via an angular filter (). The filter () is applied to an outcoupling region on at least one of the front and rear surfaces () and is configured to transmit light only within a confined range of angles with respect to the normal of the outcoupling region. The confined range extends from a lower angle limit θto an upper angle limit θ. The lower angle limit θis equal to or larger than a critical angle θ, which is given by θ=arcsin(1/n), with nbeing the refractive index of the light transmissive panel () at the outcoupling region.