Pressure sensing touch systems and methods

Patent metadata

Field	Value
Publication number	US-10228799-B2
Application number	US-201715591528-A
Country	US
Kind code	B2
Filing date	May 10, 2017
Priority date	Oct 4, 2012
Publication date	Mar 12, 2019
Grant date	Mar 12, 2019

Abstract

Pressure-sensing touch systems and methods are disclosed for sensing the occurrence of a touch event based on pressure applied at a touch location. The touch system includes a light-source system and a detector system operably adjacent respective input and output edges of a waveguide. Pressure at a touch location on the waveguide gives rise to a touch event causes the waveguide to bend or flex. The waveguide bending causes a change in the optical paths of light traveling by FTIR, causing the light distribution in the output light to change. The changes are detected and are used to determine whether a touch event occurred, as well as the time-evolution of the touch event. The changes in the output light can include polarization changes caused by birefringence induced in the waveguide by the applied pressure applied. Various detector configurations are disclosed for sensing the location and pressure of a touch event.

First claim

What is claimed is:

1. A pressure-sensing touch system for detecting a touch event caused by the application of an amount of pressure at a touch location, comprising:
a waveguide defined by a transparent sheet having a body, an upper surface, a lower surface, an input edge and an output edge, wherein the transparent sheet is bendable when pressure is applied at the touch location;
a light source system in optical communication with the input edge of the transparent sheet and configured to introduce coherent light of a select operating wavelength into the body of the transparent sheet to define coherent output light of the select operating wavelength at the output edge of the transparent sheet, wherein the coherent light travels through and within the body of the transparent sheet from the input edge to the output edge and over multiple optical paths associated with multiple guided modes each having a relative phase, wherein the coherent output light has an associated spatial intensity distribution due to an interference as defined by the relative phases of the guided modes, and where bending the transparent sheet from the application of the amount of pressure causes a change in the relative phases of the guided modes, which in turn causes a change in the spatial intensity distribution of the coherent output light due to the interference;
a detector system in optical communication with the output edge of the transparent sheet and configured to detect at least a portion of the coherent output light of the select operating wavelength that exits the output edge of the transparent sheet and detect the change in the spatial intensity distribution upon bending the transparent sheet, and in response thereto generate a detector signal; and
a controller operably connected to and configured to control the operation of the light source system and the detector system, and further configured to process the detector signal to determine whether the touch event has occurred and a pressure at the touch location.

2. The pressure-sensing touch system of claim 1 , wherein the transparent sheet has a thickness in a range from 0.05 mm to 1.5 mm.

3. The pressure-sensing touch system of claim 2 , wherein the transparent sheet consists of a glass that is substantially transparent to the light from the light source.

4. The pressure-sensing touch system of claim 1 , where the light source system includes multiple light sources and the detector system includes multiple detectors.

5. The pressure-sensing touch system of claim 1 , wherein the transparent sheet has a thickness and wherein the detector system includes at least one detector and at least one aperture arranged adjacent the at least one detector, wherein the at least one aperture has a dimension that is smaller than the thickness of the transparent sheet.

6. The pressure-sensing touch system of claim 1 , wherein the transparent sheet has a thickness and wherein the detector system includes at least one detector having a photosensitive area that is smaller in at least one direction than the thickness of the transparent sheet.

7. The pressure-sensing touch system of claim 1 , wherein the light source system includes an input optical system having one of an input optical fiber, an input prism, an input grating and an angled input edge, and wherein the detector system includes an output optical system having one of output optical fiber, an output prism, an output grating and an angled output edge.

8. The pressure-sensing touch system of claim 1 , wherein the detector system includes at least one detector operably arranged on the upper surface of the transparent sheet adjacent the output edge.

9. The pressure-sensing touch system of claim 8 , wherein the detector system includes at least one detector operably arranged on the lower surface of the transparent sheet adjacent the output edge, wherein the detectors on the upper and lower surface are arranged to provide respective detector signals that are out of phase.

10. A display system that has pressure-sensing capability, comprising:
the pressure-sensing touch system according to claim 1 ; and
a display unit having a display, with the pressure-sensing touch system operably arranged adjacent the display.

11. The display system of claim 10 , wherein the display unit has a display that includes one of capacitive and resistive touch-sensing capability.

12. The display system of claim 10 , wherein the waveguide is epoxy bonded to the display unit, with the epoxy having a refractive index lower than that of the waveguide.

13. The pressure-sensing touch system of claim 1 , wherein the light source has a divergence lower than 5 degrees in at least one direction.

14. The pressure-sensing touch system of claim 1 , wherein the light source includes an LED or a VCSEL.

15. The pressure-sensing touch system of claim 1 , wherein the light source emits light of a select polarization, and wherein the detector system includes a detector polarizer, and wherein the detector signal is representative of an amount of induced birefringence in the body of the transparent sheet caused by said application of pressure at the touch location.

16. The pressure-sensing touch system of claim 15 , wherein the light source includes a source polarizer so that the light source emits said light of said select polarization.

17. The pressure-sensing touch system of claim 16 , wherein the detector system includes first and second detector polarizers operably arranged relative to first and second detectors, respectively.

18. The pressure-sensing touch system of claim 15 , further comprising at least one support member configured to support the transparent sheet to facilitate the formation of said induced birefringence within the body of the transparent sheet.

19. The pressure-sensing touch system of claim 1 , wherein the change in the spatial intensity distribution in the output coherent light includes the movement of intensity fringes caused by the interference between the guided modes and the change in the relative phases of the guide modes, and wherein the detector detects the movement of the intensity fringes to determine the amount of pressure associated with the touch event.

20. The pressure-sensing touch system of claim 19 , further including an aperture arranged adjacent the detector to make the detection aperture limited.

21. The pressure-sensing touch system of claim 19 , further including a sloped attenuator arranged adjacent the detector to make the detection of output light position-sensitive on the detector.

22. The pressure-sensing touch system of claim 1 , wherein:
the light source emits the coherent light having a polarization state,
the detector system includes a detector polarizer, and
the detector signal is representative of an amount of change in the polarization state from the polarized coherent light traveling over different optical paths through different birefringent regions of the body of the transparent sheet caused by said application of pressure at the touch location.

23. The pressure-sensing touch system of claim 22 , wherein the transparent sheet is made of glass, and wherein the change in the polarization state is from induced birefringence in the transparent sheet and the change of the optical path of the polarized coherent light through different regions of existing birefringence that are formed in the fabrication of the transparent sheet.

24. The pressure-sensing touch sys

Assignees

• Corning Inc

Inventors

• Chen Minghan
• Gollier Jacques
• Li Ming-Jun
• Michaloski Paul Francis
• Miller William James
• Nolan Daniel Aloysius

Classifications

• G06F3/0421 Primary

  by interrupting or reflecting a light beam, e.g. optical touch-screen · CPC title

• G06F3/045

  using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact · CPC title

• G06F3/044

  by capacitive means · CPC title

• G06F2203/04109

  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 title