Touchscreen

A sensor array for detecting and locating a touch event on a touch screen (TS) having at least a first edge, a second edge, a third edge, and a fourth edge around a touch active surface, wherein the first edge and the second edge are opposing each other, and the third edge and the fourth edge are opposing each other, and having at least a first sensor array and a second sensor array positioned on the first edge and the second edge, respectively, each of the sensor arrays comprising:

• a plurality of light sensors organized in a light sensors' row configured to be positioned adjacent to the touch active surface of the TS;
• and
• a plurality of light transmitters organized in a transmitters' row positioned adjacent to and above the light sensors' row in respect to the touch active surface,
• wherein light from at least one of the light transmitters of one of the sensor arrays forms at least one direct path of light that is detected by at least one light sensor in another sensor array oppositely positioned,
• and wherein when the touch active surface of the TS is touched by a touching object, the at least one direct path of light is blocked, the touch event is detected, and wherein the location of the touch event is determined based on the location of the at least one direct path of light that is blocked;
• and
• at least one physical obstacle located on at least one of the third edge or the fourth edge, for reducing stray light arriving to the light sensors,
• wherein said stray light is light that is:
• emitted by a transmitter of the plurality of light transmitters of the first sensor array,
• scattered or reflected by structure on at least one of the third edge or the fourth edge, and
• detected by a light sensor on the second sensor array.

A method of detecting a location of a touch event in a rectangular touch screen (TS) apparatus having a rectangular display divided to a first side and a second side located one aside the other, the rectangular display has at least a first edge, a second edge, a third edge, and a fourth edge such that the first edge and the second edge that opposes the first edge are longer than the third edge and the fourth edge that opposes the third edge;

• the TS further has at least a first sensor array and at least a third sensor array, positioned near the first side and the second side of the display, respectively, and along the first edge;
• at least a second sensor array and at least a forth sensor array, positioned near the first side and the second side, respectively, along the second edge;
• at least a fifth sensor array and at least a sixth sensor array, positioned near the first side along the third edge and near the second side along the fourth edge, respectively, wherein each one of the sensor arrays comprises light transmitters and light sensors;
• the method comprising:
• a first sequence comprising:
• concurrently activating in sequence, one at a time, the light transmitters in the first sensor array and in the third sensor array to transmit light towards light sensors in the second sensor array and the fourth sensor array, respectively, each along a direct light path;
• and
• determining if at least one direct light path of the direct light paths between any of the light transmitters in the first sensor array and the light sensors in the second sensor array is blocked;
• if during the first sequence, at least one direct light path is blocked, starting a third sequence wherein the third sequence comprising:
• activating in sequence, one at a time, the light transmitters in the fifth sensor array to transmit light towards light sensors in the sixth sensor array;
• determining which of the direct light paths is blocked;
• and
• determining the location of the touch event based on the at least one direct light path that is blocked;
• if the direct light path that is blocked is between a light transmitter that is activated in the third sensor array and a light sensor in the fourth sensor array, starting a fourth sequence comprising:
• activating is sequence, one at a time, the light transmitters in the fifth sensor array to transmit light towards light sensors in the sixth sensor array;
• determining which of the direct light path or direct light paths are blocked;
• and
• determining the location of the touch event based on the at least one direct light path that is blocked;
• and
• if during the first sequence no direct light path is determined to be blocked, starting a second sequence comprising:
• concurrently activating is sequence, one at a time, the light transmitters in the second sensor array and forth sensor array to transmit light towards light sensors in the first sensor array and the third sensor array, respectively;
• and
• determining if a direct light path between any of the light transmitters in the second sensor array and the fourth sensor array and the light sensors in the first sensor array and the fourth sensor array, respectively, is blocked;
• if during the second sequence:
• a direct light path is blocked between a light transmitter in the second sensor array and a light sensor in the first sensor array, starting the third sequence;
• if during the second sequence:
• a direct light path is blocked between a light transmitter in the fourth sensor array and a light sensor in the third sensor array, starting the fourth sequence;
• and
• if during the second sequence no direct light path is blocked, starting first sequence again.