Touch detection

A touch detection system comprising:

• a substrate for providing a base for the system;
• a plurality of sensors for receiving acoustic waves and generating corresponding signals in response to received acoustic waves;
• a controller for processing the signals and detecting a touch point;
• a host device for communicating the location of the touch point with the controller;
• and an algorithm means for calculating ratios of arrival time differences of acoustic waves from the touch point to the sensors and comparing the ratios with those stored in a storage unit to determine the location of the touch point.

A touch detection system comprising:

• a substrate for providing a base for the system;
• a plurality of sensors for receiving acoustic waves and generating corresponding signals in response to received acoustic waves;
• a controller for processing the signals and detecting a touch point;
• a host device for communicating the location of the touch point with the controller;
• and an algorithm means for calculating ratios of arrival time differences of acoustic waves from the touch point to the sensors and comparing the ratios with those stored in a storage unit to determine the location of the touch point, wherein the ratios stored in the storage unit are determined based on the ratios of arrival time differences for different points on the substrate, which are calculated by the arrival times of the acoustic waves to a sensor with know locations;
• and the arrival times are determined based on one or more predetermined touch points.

A method for a touch detection system comprising an algorithm including steps of touching one or more predetermined locations on a screen;

• measuring the arrival times of acoustic waves to a sensor whose location is known;
• calculating ratio of arrival time differences between the sensor and other sensors;
• finding locations of other sensors by using the ratios of arrival time differences;
• calculating ratios for different points on the screen to generate a ratios map for the screen;
• and storing the generated ratios map in a storage unit.