PRESSURE-SENSING TOUCH SYSTEM UTILIZING OPTICAL AND CAPACITIVE SYSTEMS

• US 20140098058A1
• Filed: 10/02/2013
• Published: 04/10/2014
• Est. Priority Date: 10/04/2012
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Baharav, Izhak, King, Jeffrey Stapleton, Pikula, Dragan
• Granted Patent: US 9,557,846 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A hybrid touch system that utilizes a combination of a capacitive touch system for position sensing and an optical touch system for pressure sensing is disclosed. The optical touch system includes a transparent sheet having a surface, at least one light source and at least one detector which are operably arranged relative to the transparent sheet to transmit light through the sheet and to detect the transmitted light. Performing position sensing using the capacitive touch system simplifies the pressure-sensing optical touch system.

Claims

1. A hybrid touch system for sensing both a touch location of a touch event and an amount of pressure at the touch location, comprising:

a. a capacitive touch sensor;

b. an optical touch sensor operably arranged relative to the capacitive touch sensor;

c. a software means for utilizing the capacitive touch sensor to determine the touch location of the touch event; and

d. a software means for utilizing the optical touch sensor to determine the amount of pressure at the touch location.

2. The hybrids touch system according to claim 1, wherein the optical touch sensor utilizes total internal reflection.

3. The hybrid touch system according to claim 2, wherein the optical touch sensor comprises:

a. a transparent sheet having a top surface, a bottom surface, and a perimeter that includes an edge, wherein the touch event occurs on the top surface at the touch event location;

b. at least one light source operably arranged relative to the transparent sheet and that emits light that is coupled into the transparent sheet so that the light travels within the transparent sheet via total internal reflection; and

c. at least one detector operably disposed relative to the transparent sheet and the light source and to generate a detector electrical signal having a signal strength representative of a detected intensity of light traveling within the transparent sheet, wherein the touch event causes a change in the detected light intensity that corresponds to a change in pressure applied at the touch location.

4. The hybrid touch system according to claim 3, further comprising a controller operably coupled to the at least one light source and the at least one detector and configured to receive the detector electrical signal and determine the change in the pressure applied at the touch location.

5. The hybrid touch system according to claim 4, further comprising the light source being wavelength modulated to form intensity modulated light at the detector.

6. The hybrid touch system claim 5, wherein the detector electrical signal is processed by the controller to determine a modulation contrast representative of the change in the pressure applied at the touch event location.

7. The hybrid touch system according to claim 3, wherein the transparent sheet is substantially transparent to infrared (IR) light, wherein the emitted light from the at least one light sources comprises IR light, and wherein the at least one detector is configured to detect the IR light.

8. The hybrid touch system according to claim 1, wherein the capacitive touch sensor comprises a projected capacitance sensor.

9. The hybrid touch system according to claim 8, wherein the projected capacitance sensor comprises a mutual capacitive sensor.

10. The hybrid touch system according to claim 1, further comprising a display unit having a display, with the optical touch sensor operably arranged adjacent the display.

11. The hybrid touch system according to claim 10, wherein the capacitive sensor is arranged between the display unit and optical touch sensor.

12. A method of determining touch locations of one or more touch events on a touch surface, and amounts of pressure associated with each touch event, comprising:

a. detecting x- and y-positions of each of one or more touch events via a capacitive touch sensor;

b. resolving the x- and y-positions of each of the one or more touch events via the capacitive touch sensor;

c. detecting the amounts of pressure of each of the one or more touch events via an optical touch sensor; and

d. resolving the amounts of pressure of each of the one or more touch events via the optical touch sensor.

13. The method according to claim 12, wherein the optical touch sensor employs total internal reflection to transmit light through a transparent sheet having a top surface that defines the touch surface, and wherein the detecting the amounts of pressure includes measuring a change in the transmitted light.

14. The method according to claim 12, wherein the measuring of a change in the transmitted light includes measuring an attenuation of the transmitted light or scattering of the transmitted light.

15. A method of determining an (x,y) touch location of a touch event on a touch surface, and an amount of pressure associated with the touch event, comprising:

a. detecting an occurrence of the touch event on the touch surface via an optical touch sensor;

b. determining whether the touch event is detected by a capacitive touch sensor operably arranged relative to the optical touch sensor;

c. if the touch event is detected by the capacitive touch sensor, resolving the (x,y) touch location of the touch event via a capacitive touch sensor;

d. if the touch event is not detected by the capacitive touch sensor, resolving the (x,y) touch location of the touch event via the optical touch sensor; and

e. resolving the amount of pressure at the (x,y) touch location using the optical touch sensor.

16. The method according to claim 15, wherein the capacitive touch sensor comprises a projected capacitance sensor.

17. The method according to claim 16, wherein the projected capacitance sensor comprises a mutual capacitive sensor.

18. The method according to claim 15, wherein the optical touch sensor utilizes total internal reflection with a transparent sheet having a top surface that defines the touch surface.

19. The method according to claim 15, wherein the optical sensor and the capacitive touch sensor are part of a display.

20. The method according to claim 15, wherein the resolving of the amount of pressure includes transmitting light through a transparent sheet from a light source to a detector over an optical path that includes the touch location to generate electrical detector signals, and processing the electrical detector signals using a processor.