TOUCH SCREEN

• US 20120313895A1
• Filed: 06/10/2011
• Published: 12/13/2012
• Est. Priority Date: 06/10/2011
• Status: Abandoned Application

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Haroun, Baher S., Corsi, Marco, Ginsburg, Brian P., Rentala, Vijay B., Ramaswamy, Srinath M., Seok, Eunyoung
• Application Number:
  US13/158,010
• Publication Number:
  US 20120313895A1
• Time in Patent Office: Days
• US Class Current: 345/175
• CPC Class Codes: G06F 2203/04109 FTIR in optical digitiser, i.e. touch detection by frustrating the total internal reflection within an optical waveguide due to changes of optical properties or deformation at the touch location
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

A method for determining the location of an object on a touch panel is provided. Initially, a pulse of terahertz radiation is transmitted through a touch panel, which formed of a dielectric material such that the pulse generates a evanescent field in a region adjacent to a touch surface of the touch panel. A reflected pulse is generated by an object located within the region adjacent to the touch surface of the touch panel, and a position of the object on the touch surface of the touch panel is triangulated at least in part from the reflected pulse.

Claims

1. A method comprising:

transmitting a pulse of terahertz radiation through a touch panel formed of a dielectric material such that the pulse generates a evanescent field in a region adjacent to a touch surface of the touch panel;

generating a reflected pulse from an object located within the region adjacent to the touch surface of the touch panel; and

triangulating a position of the object on the touch surface of the touch panel at least in part from the reflected pulse.

2. The method of claim 1, wherein the step of triangulating further comprises:

receiving the reflected pulse by a first receiver and a second receiver that are separated from one another by a distance; and

calculating the position of the object based at least in part on a first elapsed time between transmission and reception at the first receiver, a second elapsed time between transmission and reception at the second receiver, and the distance.

3. The method of claim 1, wherein the reflected pulse further comprises a first reflected pulse, and wherein the step of triangulating further comprises:

generating a second reflected pulse from a reflector included in the touch panel;

receiving the first and second reflected pulses by a receiver; and

calculating the position of the objected from the first and second reflected pulses.

4. The method of claim 3, wherein the reflector is located along the periphery of the touch panel.

5. The method of claim 1, wherein the pulse further comprises a first pulse, and wherein the reflected pulse further comprises a first reflected pulse, and wherein the first pulse is transmitted by a first transceiver, and wherein the method further comprises:

transmitting a second pulse of terahertz radiation through a touch panel by a second transceiver; and

generating a second reflected pulse from an object located within the region adjacent to the touch surface of the touch panel.

6. The method of claim 5, wherein the step of triangulating further comprises triangulating the location of the object on the touch surface of the touch panel from the first and second reflected pulses.

7. An apparatus comprising:

a touch panel formed of a dielectric material that is configured to carry terahertz radiation and having a touch surface; and

a touch controller that is optically coupled to touch panel, wherein the touch controller is configured to transmit a pulse of terahertz radiation through the touch panel so as to generate a evanescent field in a region adjacent to the touch surface, and wherein the touch controller is configured to receive a reflected pulse that is generated by an object located within the region, and wherein the touch controller is configured to triangulate a position of the object on the touch surface at least in part from the reflected pulse.

8. The apparatus of claim 7, wherein the touch controller further comprises:

a signaling circuit that is configured to generate and receive terahertz radiation; and

a control circuit that is coupled to the signal circuit.

9. The apparatus of claim 8, wherein the signaling circuit further comprises:

a transceiver;

a local oscillator that is coupled to the transceiver; and

a receiver circuitry that is coupled to the transceiver.

10. The apparatus of claim 9, wherein the receiver circuitry further comprises an analog baseband circuit that averages the combined signal for a plurality of sampling periods within a digitization window to generate a plurality of averaged signals and that converts the plurality of averaged signals to a digital signal.

11. The apparatus of claim 10, wherein the analog baseband circuit further comprises:

a clock circuit;

a low noise amplifier (LNA) that is coupled to the summing circuit;

an averager that is coupled to the LNA and the clock circuit;

an analog-to-digital converter (ADC) that is coupled to the LNA and the clock circuit; and

an output circuit that is coupled to the ADC.

12. The apparatus of claim 11, wherein the transmitter further comprises:

a transmitter that is coupled to the local oscillator; and

a plurality of receivers that are spaced apart from one another and that are each coupled to the receiver circuitry.

13. The apparatus of claim 12, wherein the touch panel further comprises a reflector.

14. A method comprising:

transmitting a pulse of terahertz radiation through a touch panel formed of a dielectric material such that the pulse generates a evanescent field in a region adjacent to a touch surface of the touch panel;

generating a plurality of reflected pulses, wherein a first reflected pulse is generated by a object located within the region adjacent to the touch surface of the touch panel; and

triangulating a position of the object on the touch surface of the touch panel at least in part from the plurality of reflected pulses.

15. The method of claim 14, wherein the object further comprises a first object, and wherein the position further comprises a first position, and wherein a second reflected pulse of the plurality of reflected pulses is generated by a object located within the region adjacent to the touch surface of the touch panel and at a second location.

16. The method of claim 15, wherein the step of triangulating further comprises:

receiving the plurality of reflected pulses by a first receiver and a second receiver that are separated from one another by a distance; and

calculating the position of the object based at least in part on the plurality of reflected pulses.

17. The method of claim 16, wherein a third reflected pulse of the plurality of reflected pulses is generated by a reflector.

18. The method of claim 17, wherein the reflector is located along the periphery of the touch panel.