US 9,811,209 B2
Touch determination with improved detection of weak interactions
Tomas Christiansson, Torna-Hallestad (SE); and Nicklas Ohlsson, Bunkeflostrand (SE)
Assigned to FLATFROG LABORATORIES AB, Lund (SE)
Appl. No. 14/380,063
Filed by FlatFrog Laboratories AB, Lund (SE)
PCT Filed Feb. 19, 2013, PCT No. PCT/SE2013/050137
§ 371(c)(1), (2) Date Aug. 20, 2014,
PCT Pub. No. WO2013/126005, PCT Pub. Date Aug. 29, 2013.
Claims priority of provisional application 61/601,114, filed on Feb. 21, 2012.
Claims priority of application No. 1250150 (SE), filed on Feb. 21, 2012.
Prior Publication US 2016/0070415 A1, Mar. 10, 2016
Int. Cl. G06F 3/042 (2006.01); G06F 3/041 (2006.01)
CPC G06F 3/0421 (2013.01) [G06F 3/0418 (2013.01); G06F 2203/04104 (2013.01); G06F 2203/04109 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method of enabling touch determination based on an output signal from a touch-sensitive apparatus, the touch-sensitive apparatus including a panel configured to conduct signals from a plurality of incoupling points to a plurality of outcoupling points, thereby defining detection lines that extend across a surface portion of the panel between pairs of incoupling and outcoupling points, the touch-sensitive apparatus further including at least one signal generator coupled to the plurality of incoupling points to generate the signals, and at least one signal detector coupled to the plurality of outcoupling points to generate the output signal, the output signal indicative of interaction between one or more touching objects and one or more of the detection lines, wherein the method comprises:
processing the output signal to obtain observed values for a plurality of the detection lines;
for each of the plurality of the detection lines
computing a normalization value for the detection line as a function of the observed value for the detection line,
generating a projected value for the detection line based on a projection function that defines a functional relation between a fitted interaction pattern and the projected value for the detection line,
calculating a difference value between the observed value for the detection line and the projected value for the detection line,
computing a normalized difference value for the difference value based on the normalization value for the detection line,
updating the fitted interaction pattern based on an optimization function to minimize the normalized difference value; and
processing the fitted interaction pattern to determine touch interaction.