On a substrate formed or resting display arrangement
A touch screen apparatus, including a display unit including a touch surface, a number of light pulse emitting units, connecting to the display unit, for emitting light pulses over and across the touch surface, a number of light pulse receiving units, connected to the display unit, for measuring amounts of light received from the light pulse emitting units, circuitry, connected to the light pulse emitting units and to the light pulse receiving units, for selectively activating, at any given time, one or more of the light pulse emitting units and the light pulse receiving units, wherein the circuitry activates three or more light pulse emitting units and only one light pulse receiving unit during a designated time interval, and a calculating unit, connected to the light pulse receiving units, to determine the location of an object touching the touch surface, based on the measured amounts of light received at the receiving units.
1. A touch screen apparatus, comprising:
a display unit comprising a touch surface;
a number of light pulse emitting units, connecting to said display unit, for emitting light pulses over and across said touch surface;
a number of light pulse receiving units, connected to said display unit, for measuring amounts of light received from said light pulse emitting units;
circuitry, connected to said light pulse emitting units and to said light pulse receiving units, for selectively activating, at any given time, one or more of said light pulse emitting units and said light pulse receiving units, wherein said circuitry activates three or more light pulse emitting units and only one light pulse receiving unit during a designated time interval; and
a calculating unit, connected to said light pulse receiving units, to determine the location of an object touching said touch surface, based on the measured amounts of light received at said receiving units.
2. The touch screen apparatus of claim 1 wherein said circuitry activates a light pulse emitting unit for a pulse time no longer than 10 μs.
3. The touch screen apparatus of claim 1 wherein said circuitry activates a light pulse emitting unit with an electrical current of at least 1A.
4. The touch screen apparatus of claim 1 wherein said circuitry activates a light pulse emitting unit slightly before activating a light pulse receiving unit to receive the emitted light pulse.
5. The touch screen apparatus of claim 1 wherein said circuitry pauses for an idling time between successive activations of light pulse emitting units.
6. The touch screen apparatus of claim 1 wherein said circuitry increases the intensities of light pulse emitting units to suppress disturbances caused by ambient light.