METHODS AND APPARATUS FOR SENSING TOUCH EVENTS ON A DISPLAY

• US 20110122091A1
• Filed: 11/25/2009
• Published: 05/26/2011
• Est. Priority Date: 11/25/2009
• Status: Active Grant

• Current Assignee: Corning Incorporated
• Original Assignee: Corning Incorporated
• Inventors: Charbonneau-Lefort, Mathieu, King, Jeffrey S., Trutna, William R., Orsley, Timothy J.
• Granted Patent: US 8,436,833 B2
• Time in Patent Office: Days
• US Class Current: 345/175
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen

Abstract

Methods and apparatus provide for a touch sensitive display, in which a transparent layer is disposed over a display layer; light is directed to propagate into and/or through the transparent layer; scattered light is measured in response to an object touching a surface the transparent layer and disturbing the propagation of the light therethrough; and one or more positions at which the object touches the transparent layer are computed based on signals obtained by the step of measuring the scattered light.

Claims

1. A touch sensitive display, comprising:

a display layer;

a transparent layer disposed over the display layer;

at least one source directing light to propagate into and/or through the transparent layer;

at least one light sensing element in communication with the transparent layer and operating to receive scattered light in response to an object touching a surface the transparent layer and disturbing the propagation of the light therethrough; and

a control circuit including a processor receiving signals from the at least one light sensing element indicative of the scattered light, and computing one or more positions at which the object touches the transparent layer.

2. The touch sensitive display of claim 1, wherein:

the at least one source is in communication with the transparent layer such that the light is coupled into the transparent layer and propagates in a guided mode; and

the object touching the transparent layer causes a discontinuity and disrupts the guided mode of the light, thereby producing the scattered light.

3. The touch sensitive display of claim 1, wherein:

the at least one source includes at least first and second sources in communication with one or more edges of the transparent layer; and

the light emanating from the respective first and second sources includes at least one distinguishing characteristic such that the processor is operable to distinguish certain of the signals to be from scattered light produced in response to the first source, and certain others of the signals to be from scattered light produced in response to the second source.

4. The touch sensitive display of claim 3, wherein the at least one distinguishing characteristic includes at least one of:

a differing wavelength of the light emanating from the first source as compared to the light emanating from the second source;

a temporal component whereby the light emanates from the first source at differing times as compared to the light emanating from the second source;

a modulation component whereby the light emanating from the first source is modulated with a first code and the light emanating from the second source is modulated with a second code; and

a further modulation component whereby the light emanating from the first source is modulated with a first frequency and the light emanating from the second source is modulated with a second frequency.

5. The touch sensitive display of claim 4, further comprising:

at least a first source in communication with a first edge of the transparent layer and producing light within a first range of wavelengths; and

at least a second source in communication with a second edge of the transparent layer and producing light within a second range of wavelengths differing outside the first range of wavelengths,

wherein the processor computes the one or more positions at which the object touches the transparent layer based in part on distinguishing that certain of the signals are produced in response to light within the first range of wavelengths from a particular one or more of the light sensing elements, and certain others of the signals are produced in response to light within the second range of wavelengths from a particular one or more others of the light sensing elements.

6. The touch sensitive display of claim 5, further comprising low reflectance pigment disposed along an edge of the transparent layer opposite the first edge, and along an edge of the transparent layer opposite the second edge, thereby reducing light reflections at one or more edges of the transparent layer.

7. The touch sensitive display of claim 6, wherein:

the first and second edges are opposite one another such that each such edge includes low reflectance pigment thereon; and

a respective window through the low reflectance pigment is disposed adjacent the at least first and second sources such that the light therefrom is coupled into the transparent layer.

8. The touch sensitive display of claim 7, further comprising:

at least one first filter disposed between the at least first source and the transparent layer, and operating to attenuate light substantially outside the first range of wavelengths; and

at least one second filter disposed between the at least second source and the transparent layer, and operating to attenuate light substantially outside the second range of wavelengths.

10. The touch sensitive display of claim 4, wherein:

the control circuit includes a light source driving circuit operating to energize the at least first and second sources in time sequence; and

the processor computes the one or more positions at which the object touches the transparent layer based in part on distinguishing that certain of the signals are produced at certain times in response to light from a particular one or more of the light sensing elements, and certain others of the signals are produced at certain other times in response to light from a particular one or more others of the light sensing elements.

11. The touch sensitive display of claim 10, wherein the at least first and second sources produce light only within a range of infrared wavelengths.

12. The touch sensitive display of claim 4, wherein at least one of:

the control circuit includes a modulation circuit operating to modulate the first and second sources such that the respective light therefrom includes the first and second codes;

the first and second codes are orthogonal codes;

the orthogonal codes are Walsh codes; and

the processor computes the one or more positions at which the object touches the transparent layer based in part on distinguishing that certain of the signals include the first code and are therefore produced in response to light from a particular one or more of the light sensing elements, and certain others of the signals include the second code and are therefore produced in response to light from a particular one or more others of the light sensing elements.

13. The touch sensitive display of claim 4, wherein:

the control circuit includes a modulation circuit operating to modulate the first and second sources such that the respective light therefrom includes the first and second frequencies; and

the processor computes the one or more positions at which the object touches the transparent layer based in part on distinguishing that certain of the signals include the first frequency and are therefore produced in response to light from a particular one or more of the light sensing elements, and certain others of the signals include the second frequency and are therefore produced in response to light from a particular one or more others of the light sensing elements.

14. The touch sensitive display of claim 1, wherein:

the at least one source is a backlighting element of the display layer and is in communication with the transparent layer such that the light propagates through the transparent layer in a direction perpendicular to the surface thereof; and

the object touching the transparent layer causes a discontinuity and causes some of the light to couple into the transparent layer, thereby producing the scattered light.

15. The touch sensitive display of claim 1, wherein:

the object fluoresces in response to incident light from touching the surface of the transparent layer; and

fluorescent light from the object couples into the transparent layer, thereby producing the scattered light.

16. The touch sensitive display of claim 15, wherein:

the at least one source produces light within a first range of wavelengths;

the fluorescent light from the object is at one or more wavelengths substantially outside the first range of wavelengths; and

the control circuit operates to distinguish between the fluorescent light and the light propagating from the at least one source at least in part by determining that the signals produced in response to the fluorescent light are caused by light energy outside the first range of wavelengths.

17. The touch sensitive display of claim 1, further comprising a light suppressing mechanism operating to reduce light reflections at one or more edges of the transparent layer.

18. The touch sensitive display of claim 17, wherein the light suppressing mechanism includes a low reflectance pigment disposed along at least one edge of the transparent layer opposite the at least one source.

19. The touch sensitive display of claim 17, wherein the light suppressing mechanism includes a tapering thickness of the transparent layer at an edge thereof opposite the at least one source.

20. The touch sensitive display of claim 1, further comprising an active stylus containing the at least one source.

21. The touch sensitive display of claim 20, wherein the active stylus further includes a light diffusing element to diffuse the light from the at least one source prior to the light propagating into and/or through the transparent layer.

22. The touch sensitive display of claim 20, wherein the active stylus further includes a switch circuit operating to activate the at least one source only when the stylus is in contact with the transparent layer.

9. The touch sensitive display of claim 9, wherein at least one of the first and second filters including an infrared filter operating to attenuate light in a infrared range of wavelengths.

23. A method, comprising:

disposing a transparent layer over a display layer;

directing light to propagate into and/or through the transparent layer;

measuring scattered light in response to an object touching a surface the transparent layer and disturbing the propagation of the light therethrough; and

computing one or more positions at which the object touches the transparent layer based on signals obtained by the step of measuring the scattered light.

24. The method of claim 23, further comprising:

coupling the light into the transparent layer such that the light propagates therein in a guided mode; and

disrupting the guided mode of the light by touching the surface of the transparent layer.

25. The method of claim 23, further comprising:

directing the light into the transparent layer via at least first and second sources in communication with one or more edges of the transparent layer;

including at least one distinguishing characteristic in the light emanating from the respective first and second sources; and

distinguishing, based upon the at least one distinguishing characteristic, that certain of the signals to be from scattered light produced in response to the first source and measured at a particular one or more locations of the transparent layer, and certain others of the signals to be from scattered light produced in response to the second source and received from a particular one or more others locations of the transparent layer.

26. The method of claim 25, wherein the at least one distinguishing characteristic includes at least one of:

a differing wavelength of the light emanating from the first source as compared to the light emanating from the second source;

a temporal component whereby the light emanates from the first source at differing times as compared to the light emanating from the second source;

a modulation component whereby the light emanating from the first source is modulated with a first code and the light emanating from the second source is modulated with a second code; and

a further modulation component whereby the light emanating from the first source is modulated with a first frequency and the light emanating from the second source is modulated with a second frequency.