A touch screen comprising: a housing; a display having four edges and mounted in said housing; a plurality of collimating lenses (439 - 443, 506 - 510) mounted in said housing along the four edges of said display and arranged so as to be shift-aligned relative to one another on opposing edges; a plurality of light pulse emitters (201, 202) mounted in said housing along two adjacent edges of said display, that are spaced apart from and transmit light pulses through collimating lenses (439, 440) that are mounted along the two adjacent edges, and over said display; a plurality of light pulse receivers (301 - 303) mounted in said housing along the opposite adjacent edges, that are spaced apart from and receive the light pulses through [[said]] collimating lenses (441 - 443) that are mounted along the opposite adjacent edges, wherein wide light pulses transmitted by neighboring emitters (201, 202) through neighboring lenses (439, 440) are received by a common receiver; and a calculating unit, mounted in said housing and connected to said receivers (301 - 303), that calculates a location of a pointer on said display that partially blocks the light pulses transmitted by said emitters (201, 202), based on outputs of the common receiver, by assigning coordinates (Xa, Xb, Xn) to receivers for which a value for emitter-receiver pairs deviating significantly from a baseline light value is detected, and by calculating a weighted average of the assigned coordinates, wherein each coordinate's weight in the average corresponds to a normalized signal difference between the baseline light value and an actual detected value. a housing; a display having four edges and mounted in said housing; a plurality of collimating lenses (439 - 443, 506 - 510) mounted in said housing along the four edges of said display and arranged so as to be shift-aligned relative to one another on opposing edges; a plurality of light pulse emitters (201, 202) mounted in said housing along two adjacent edges of said display, that are spaced apart from and transmit light pulses through collimating lenses (439, 440) that are mounted along the two adjacent edges, and over said display; a plurality of light pulse receivers (301 - 303) mounted in said housing along the opposite adjacent edges, that are spaced apart from and receive the light pulses through [[said]] collimating lenses (441 - 443) that are mounted along the opposite adjacent edges, wherein wide light pulses transmitted by neighboring emitters (201, 202) through neighboring lenses (439, 440) are received by a common receiver; and a calculating unit, mounted in said housing and connected to said receivers (301 - 303), that calculates a location of a pointer on said display that partially blocks the light pulses transmitted by said emitters (201, 202), based on outputs of the common receiver, by assigning coordinates (Xa, Xb, Xn) to receivers for which a value for emitter-receiver pairs deviating significantly from a baseline light value is detected, and by calculating a weighted average of the assigned coordinates, wherein each coordinate's weight in the average corresponds to a normalized signal difference between the baseline light value and an actual detected value.