Pressure-sensing touch system utilizing optical and capacitive systems

• US 9,557,846 B2
• Filed: 10/02/2013
• Issued: 01/31/2017
• 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
• Primary Examiner(s): Siddiqui, Md Saiful A
• Application Number:
  US14/044,030
• Publication Number:
  US 20140098058A1
• Time in Patent Office: 1,217 Days
• Field of Search: 345/166, 345173-179, 178/18.06, 178/18.09
• US Class Current: 1/1
• 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, wherein the optical touch sensor includes;

i. a transparent sheet having a monolithic body in the form of a single element made of a single material, the monolithic body 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 and has an amount of contact area that corresponds to the amount of pressure;

ii. 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 monolithic body of the transparent sheet via total internal reflection from the top and bottom surfaces only; and

iii. at least one detector operably disposed immediately adjacent to the transparent sheet and that generates a detector electrical signal having a signal strength representative of a detected intensity of light traveling within the monolithic body of the transparent sheet, wherein the touch event at the top surface of the transparent sheet scatters the light traveling within the monolithic body of the transparent sheet, thereby causing a change in the detected light intensity that corresponds to a change in the amount of contact area at the touch location that is representative of a change in the pressure applied at the touch location;

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 based on the detector electrical signal.

2. The hybrid touch system according to claim 1, further comprising a controller that include said software means and that is 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 using said software means.

3. The hybrid touch system according to claim 2, further comprising the light source being wavelength modulated to form intensity modulated light at the detector.

4. The hybrid touch system claim 3, 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.

5. The hybrid touch system according to claim 1, 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.

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

7. The hybrid touch system according to claim 6, wherein the projected capacitance sensor comprises a mutual capacitive sensor.

8. 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.

9. The hybrid touch system according to claim 8, wherein the capacitive sensor is arranged between the display unit and optical touch sensor.

10. 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 that includes a transparent sheet having a monolithic body in the form of a single element made of a single material, the monolithic body having a lower surface and an upper surface, wherein the one or more touch events occur at the upper surface, wherein light travels within the monolithic body by total internal reflection (TIR) from the upper and lower surfaces only, and wherein the TIR light is scattered by each touch event at the top surface in proportion to an amount of contact area associated with each touch event so that a detector arranged immediately adjacent the transparent sheet generates a detector signal representative of a change in the amount of transmitted TIR light due to said light scattering in proportion to the amount of contact area; and

d. resolving the amounts of pressure of each of the one or more touch events via the optical touch sensor based on the amount of contact area associated with each touch event.

11. The method according to claim 10, wherein the measuring of a change in the amount of transmitted TIR light includes measuring an attenuation of the transmitted TIR light.

12. 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. whenever 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. whenever 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, wherein the optical touch sensor includes a transparent sheet having a monolithic body in the form of a single element made of a single material, the monolithic body having a lower surface and an upper surface, wherein the upper surface defines the touch surface and wherein light travels within the body by total internal reflection (TIR) from the upper and lower surfaces only, and wherein the TIR light is scattered by the touch event at the top upper surface in proportion to an amount of contact area associated with the touch event so that a detector arranged immediately adjacent the transparent sheet generates a detector signal representative of a change in the amount of transmitted TIR light due to said light scattering, and wherein resolving the amount of pressure of the touch event is based on the amount of contact area.

13. The method according to claim 12, wherein the capacitive touch sensor comprises a projected capacitance sensor.

14. The method according to claim 13, wherein the projected capacitance sensor comprises a mutual capacitive sensor.

15. The method according to claim 12, wherein the amount of contact area is defined by a finger applied to the touch surface at the touch location.

16. The method according to claim 12, wherein the optical sensor and the capacitive touch sensor are part of a display.

17. The method according to claim 12, wherein the resolving of the amount of pressure includes processing the electrical detector signals using a processor.