Patent ID: 8471830

Claim:
An interface arrangement for receiving input commands in a mobile terminal, comprising: a display device adapted to present visual information to a user, at least one array of light sources arranged along at least one first side of the display device, each array of light sources being configured to transmit light pulses over the display device, at least one array of light detectors arranged along at least one second side of the display device, each array of light detectors being configured to receive a part of the energy in the transmitted light pulses, a processing unit adapted to control the at least one array of light sources such that a respective light pulse is repeatedly transmitted from each light source according to a predefined sequence, and to receive information pertaining to light energy registered by the at least one array of light detectors, characterized in that the processing unit is adapted to: record an initial measurement value registered by at least one light detector prior to transmitting the light pulse of a designated light source, the initial measurement value representing an ambience light intensity, and determine whether or not a light-obstructive object is present on the display device between the designated light source and at least one light detector based on the initial measurement value and a secondary measurement value registered by at least one light detector during transmission of light from the designated light source, and a digitizing unit configured to receive measurement values from the at least one array of light detectors and in response thereto deliver digital data to the processing unit, wherein the processing unit is configured to control the at least one array of light sources such that each light pulse has a duration exceeding a time of the digitizing unit for producing digital data based on the received measurement values.