Optical touchpad with three-dimensional position determination

• US 8,094,136 B2
• Filed: 07/06/2006
• Issued: 01/10/2012
• Est. Priority Date: 07/06/2006
• Status: Active Grant

• Current Assignee: FlatFrog Laboratories AB
• Original Assignee: FlatFrog Laboratories AB
• Inventors: Eliasson, Jonas Ove Philip, Larsen, Niels Agersnap, Bastue, Jens, Ostergaard, Jens Wagenblast Stubbe
• Primary Examiner(s): Shalwala, Bipin
• Assistant Examiner(s): SPAR, ILANA L
• Application Number:
  US11/480,893
• Publication Number:
  US 20080007542A1
• Time in Patent Office: 2,014 Days
• Field of Search: 178/18.01, 178/18.09, 345156-158, 345/173, 345/175, 345/176
• 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 3/0346 with detection of the device orientation or free movement in a 3D space, e.g. 3D mice, 6-DOF [six degrees of freedom] pointers using gyroscopes, accelerometers or tilt-sensors
• CPC Class Codes: G06F 3/0425 using a single imaging device like a video camera for tracking the absolute position of a single or a plurality of objects with respect to an imaged reference surface, e.g. video camera imaging a display or a projection screen, a table or a wall surface, on which a computer generated image is displayed or projected tracking a projected light spot to determine a position on a display surface G06F3/0386
• CPC Class Codes: G06F 3/0428 by sensing at the edges of the touch surface the interruption of optical paths, e.g. an illumination plane, parallel to the touch surface which may be virtual sensing beam interruptions in a planar beam grid of an optical touch-screen G06F3/0421

Abstract

An optical touchpad that may be able to provide accurate, reliable information about the position of an object in three-dimensions. The optical touchpad may enable a determination as to whether the object is engaged with the touchpad or hovering just above the touchpad. When the object is in contact with the optical touchpad, the optical touchpad may enable a determination of the force applied by the object to the optical touchpad. The optical touchpad may enable a determination of an object type of the object. These and other determinations of information related to the object may enhance the control provided by the touchpad system to the user as an electronic interface. The operation of the optical touchpad may further enable an enhanced frame rate, reduced optical noise in the optical signal(s) guided to the one or more sensors, augment the ruggedness of the optical touchpad, an enhanced form factor (e.g., thinner), and/or provide other advantages.

Claims

1. A method of determining information related to a position of an object, the method comprising:

providing electromagnetic radiation to a signal waveguide layer of a waveguide between a first surface and a second surface of the signal waveguide layer, the waveguide comprising;

an interface surface that is generally planar and forms a touchpad surface;

an intervening layer having a first index of refraction and being disposed within the waveguide;

the signal waveguide layer having a second index of refraction that is greater than the first index of refraction and being disposed within the waveguide abutting the intervening layer on a side of the intervening layer opposite from the outer surface,

wherein the abutment between the signal waveguide layer and the intervening layer forms a generally planar boundary therebetween, and

wherein the signal waveguide layer is optically coupled to (i) the one or more emitters to receive electromagnetic radiation emitted therefrom, and (ii) one or more detectors such that the detectors receive electromagnetic radiation from the signal waveguide layer;

a total internal reflection mirror having a predetermined critical angle, the total internal reflection mirror being formed at the boundary between the signal waveguide layer and the intervening layer such that electromagnetic radiation that is incident on the total internal reflection mirror from within the signal waveguide layer is deflected back into the signal waveguide layer if the electromagnetic radiation becomes incident on the total internal reflection mirror at an angle of incidence greater than the critical angle;

a reflective surface formed on a side of the signal waveguide layer opposite from the boundary between the signal waveguide layer and the intervening layer, wherein the reflective surface reflects electromagnetic radiation that is incident on the reflective surface from within the signal waveguide layer back into the signal waveguide layer; and

a plurality of microstructures disposed within the waveguide, wherein the microstructures are formed (i) to receive electromagnetic radiation from the signal waveguide layer that is traveling with an angle of incidence to the plane of the boundary between the signal waveguide layer and the intervening layer greater than the critical angle of the total internal reflection mirror, and (ii) to leak at least a portion of the received electromagnetic radiation from the signal waveguide layer into the intervening layer toward the interface surface,

wherein the microstructures are further formed such any of the portion of the received electromagnetic radiation that is leaked from the signal waveguide layer by the microstructures that becomes reflected at the boundary between the waveguide and ambient atmosphere to travel back toward the signal waveguide layer will not become incident on any of the one or more detectors;

receiving electromagnetic radiation from between the first surface and the second surface of the signal waveguide layer; and

determining a magnitude of a distance between an object in the proximity of the interface surface and the interface surface for a range of possible distance magnitudes between the interface surface and a maximum detectable distance from the interface surface, the magnitude of the distance being determined based on the electromagnetic radiation received from between the first surface and the second surface.

2. The method of claim 1, wherein the distance between the object and the interface surface are determined based on an intensity of the electromagnetic radiation.

3. The method of claim 1, further comprising determining a position of the object in a plane generally parallel with the plane of the interface surface based on the electromagnetic radiation received from between the first surface and the second surface.

4. The method of claim 3, wherein the position of the object in a plane generally parallel with the plane of the interface surface is determined based on the directionality of the received electromagnetic radiation.

5. The method of claim 1, wherein if the distance between the object and the interface surface is zero because the object is in contact with the interface surface, the method further comprises determining a force applied by the object to the interface surface based on the electromagnetic radiation received from between the first surface and the second surface.

6. The method of claim 5, wherein the force applied by the object to the interface surface is determined based on the intensity of the electromagnetic radiation received from between the first surface and the second surface.

7. The method of claim 1, further comprising determining an object type of the object based on the electromagnetic radiation received from between the first surface and the second surface.

8. The method of claim 7, wherein the object type comprises one or more of a finger, a stylus, or a pen.

9. The method of claim 1, further comprising determining a tilt direction of the object with respect to the plane of the interface surface.

13. The system of claim 1, wherein the one or more processor determine a position of the object in a plane generally parallel with the plane of the interface surface based on the output signals of the one or more detectors.

14. The system of claim 1, wherein if the distance between the object and the interface surface is zero because the object is in contact with the interface surface, the processor determines a force applied by the object to the interface surface based on the output signals from the one or more detectors.

15. The system of claim 1, wherein the one or more processors determine an object type of the object based on the output signals from the one or more detectors.

16. The system of claim 15, wherein the object type comprises one or more of a finger, a stylus, or a pen.

17. The system of claim 1, wherein the one or more processors determine a tilt direction of the object with respect to the plane of the interface surface based on the output signals from the detectors.

18. The system of claim 1, wherein the one or more properties of the electromagnetic radiation received by the one or more detectors that correspond to the one or more output signals generated by the one or more detectors comprise one or more of an intensity, a directionality, a wavelength, or a modulation.

19. The optical touchpad system of claim 1, wherein the range of possible distance magnitudes includes at least three possible distance magnitudes.

20. The optical touchpad system of claim 1, wherein the one or more processors are further configured to determine a three dimensional position of the object if the object is located within the maximum detectable distance from the interface surface.

10. An optical touchpad system comprising:

one or more emitters configured to emit electromagnetic radiation;

one or more detectors configured to receive electromagnetic radiation and output one or more output signals that correspond to one or more properties of the received electromagnetic radiation; and

a waveguide that guides a portion of the electromagnetic radiation emitted by the emitters to the detectors, the waveguide comprising;

an interface surface that is generally planar and forms a touchpad surface;

an intervening layer having a first index of refraction and being disposed within the waveguide;

a signal layer having a second index of refraction that is greater than the first index of refraction and being disposed within the waveguide abutting the intervening layer on a side of the intervening layer opposite from the outer surface,

wherein the abutment between the signal layer and the intervening layer forms a generally planar boundary therebetween, and

wherein the signal layer is optically coupled to (i) the one or more emitters to receive electromagnetic radiation emitted therefrom, and (ii) the one or more detectors such that the detectors receive electromagnetic radiation from the signal layer;

a total internal reflection mirror having a predetermined critical angle, the total internal reflection mirror being formed at the boundary between the signal layer and the intervening layer such that electromagnetic radiation that is incident on the total internal reflection mirror from within the signal layer is deflected back into the signal layer if the electromagnetic radiation becomes incident on the total internal reflection mirror at an angle of incidence greater than the critical angle;

a reflective surface formed on a side of the signal layer opposite from the boundary between the signal layer and the intervening layer, wherein the reflective surface reflects electromagnetic radiation that is incident on the reflective surface from within the signal layer back into the signal layer; and

a plurality of microstructures disposed within the waveguide, wherein the microstructures are formed (i) to receive electromagnetic radiation from the signal layer that is traveling with an angle of incidence to the plane of the boundary between the signal layer and the intervening layer greater than the critical angle of the total internal reflection mirror, and (ii) to leak at least a portion of the received electromagnetic radiation from the signal layer into the intervening layer toward the interface surface,

wherein the microstructures are further formed such any of the portion of the received electromagnetic radiation that is leaked from the signal layer by the microstructures that becomes reflected at the boundary between the waveguide and ambient atmosphere to travel back toward the signal layer will not become incident on any of the one or more detectors.

11. The optical touchpad system of claim 10, wherein the microstructures are further formed (iii) to receive electromagnetic radiation that has been leaked from the signal layer by the microstructures and has been scattered and/or reflected by an object at or near the interface surface to travel back toward the signal layer at an angle of incidence to the plane of the boundary between the signal layer and the intervening layer that is less than the critical angle of the total internal reflection mirror, and (iv) to bend the path of at least a portion of the received electromagnetic radiation such that the at least a portion of the received electromagnetic radiation is guided to the one or more detectors by the reflective surface and the total internal reflection mirror.

12. The optical touchpad system of claim 10, further comprising

one or more processors configured to receive the one or more output signals from the one or more detectors and determine a magnitude of a distance between an object in the proximity of the interface surface and the interface surface for a range of possible distance magnitudes between the interface surface and a maximum detectable distance from the interface surface, the one or more processors being configured to determine the magnitude of the distance based on the output signals of the one or more detectors.