Touch detection

Abstract

A touch detection device for detecting touches on a given surface. The inventive device includes a surface where a touch generates acoustic waves, transducers that detect these waves, a controller that calculate the location of the touch and a host device where the touch position is used to communicate with the application program. The screen is formed from any material that is capable of propagating acoustic waves. Plurality transducers are placed on the screen. These transducers detect acoustic waves generated on the screen. The screen is calibrated by touching it once and a map of arrival time ratios are generated and saved in the storage unit. During the real time operation, a touch on the screen generates acoustic waves that are detected by transducers. The output of each transducer is sent to a controller unit where the time differences and their ratios are calculated and compared to time ratios in the storage unit to detect the touch location.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Various other objects, features and attendant advantages of the present invention will become fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein:

FIG. 1 is Screen.

FIG. 2 is System Components.

FIG. 3 is Controller.

FIG. 4 is Algorithm to calibrate the screen.

FIG. 5 is Algorithm to detect the touch.

FIG. 6 is Geometry to determine transducer locations.

Claims

1. A touch detection device comprising: a substrate for providing a base for the device; plurality of sensors for detecting acoustic waves and converting acoustic energy to electrical energy; an analog to digital converter for converting analog signal to digital signal, a controller and an algorithm for processing the digital signal and finding the touch location by means of calculating the ratio of time of arrival differences of acoustic waves from the touch point to plurality of sensors and comparing these ratios with those stored in the storage unit.

2. A system in accordance with claim 1, wherein said means for providing base for the device comprises a substrate that can propagate acoustic waves.

3. A system in accordance with claim 1, wherein said means for detecting acoustic waves and converting acoustic energy to electrical energy comprises transducers.

4. A system in accordance with claim 1, wherein said means for detecting touch position comprises a storage unit.

5. A touch detection device comprising: a substrate for providing a base for the device; plurality of sensors for detecting acoustic waves and converting acoustic energy to electrical energy; an analog to digital converter for converting analog signal to digital signal, a controller for processing digital signal and for detecting the touch position and communicating the location to a host computer; an algorithm for calculating the touch location comprising steps: Finding the arrival time differences of acoustic waves between several sensor pairs;Finding the ratio of time differences;Correlating the ratio of time differences with the ratio of time differences in the storage unit;Finding the touch location based on the correlation results.

6. A system in accordance with claim 5, wherein said means for calculating time differences comprises counters that count wave travel time from touch locations to sensors.

7. A system in accordance with claim 5, wherein said host computer is a portable device.

8. A system in accordance with claim 5 wherein said substrate is located on a portable device.

9. A system in accordance with claim 5, wherein said controller is part of the portable device.

10. A system in accordance with claim 5, wherein said algorithm resides in the portable device.

11. A system in accordance with claim 5, wherein said digital to analog converter resides in the portable device.

12. A system in accordance with claim 5, wherein said counter is implemented in hardware.

13. A system in accordance with claim 5, wherein said counter is implemented in software.

14. A touch detection device comprising: a substrate for providing a base for the device; plurality of sensors for detecting acoustic waves and converting acoustic energy to electrical energy; an analog to digital converter for converting analog signal to digital signal, a controller for processing the digital signal and for detecting the touch position and communicating the location to a host computer; an algorithm for calculating the location of sensors and calculating arrival time ratios based on a single touch on the screen, the algorithm comprising the following steps: Touching one or more predetermined locations on the screen;Measuring the arrival times of acoustic waves to a sensor where its location is known;Calculating the ratio of arrival time differences;Finding the locations of other sensors by using time difference ratios;Calculating ratios for different points on the screen therefore generating a map for the screen;Storing the generated map in a storage device.

15. System in accordance with claim 14, wherein said means for touching a known location is performed with any device such as metal, finger.

16. System in accordance with claim 15, wherein said storage element is implemented as a stand alone chip.

17. System in accordance with claim 15, wherein said storage element is implemented in the microcontroller circuit.