METHODS FOR DETERMINING A TOUCH LOCATION ON A TOUCH SCREEN

• US 20110169780A1
• Filed: 03/22/2011
• Published: 07/14/2011
• Est. Priority Date: 12/10/2002
• Status: Active Grant

• Current Assignee: Neonode, Inc.
• Original Assignee: Neonode, Inc.
• Inventors: Goertz, Magnus, Eriksson, Thomas, Pettersson, Robert, Sparf, Lars, Jansson, Anders, Karlsson, John, Kvist, Niklas, Shain, Joseph
• Granted Patent: US 8,902,196 B2
• Time in Patent Office: Days
• US Class Current: 345/175
• CPC Class Codes: G06F 2203/04101 2.5D-digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface and also measures the distance of the input means within a short range in the Z direction, possibly with a separate measurement setup
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 2203/04808 Several contacts: gestures triggering a specific function, e.g. scrolling, zooming, right-click, when the user establishes several contacts with the surface simultaneously; e.g. using several fingers or a combination of fingers and pen
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/04186 Touch location disambiguation
• CPC Class Codes: G06F 3/042 by opto-electronic means
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• 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
• CPC Class Codes: G06F 3/04845 for image manipulation, e.g. dragging, rotation, expansion or change of colour
• CPC Class Codes: G06F 3/04883 for inputting data by handwriting, e.g. gesture or text

Abstract

A method of determining a touch coordinate on a touch screen, including providing a display, a plurality of collimating lenses along two opposite edges of the display, the collimating lenses being arranged along the two edges so as to be shift-aligned relative to one another, a plurality of light pulse emitters that transmit light pulses through the collimating lenses of a first of the two edges over the display, and a plurality of light pulse receivers that receive the light pulses through the collimating lenses of the opposite of the two edges, and that output values representing the received light pulses, wherein light pulses emitted by each emitter are detected by at least two of the receivers, wherein each receiver detects light pulses emitted by at least two emitters, and wherein each receiver has expected values for emitter-receiver pairs when light pulses are not blocked, selecting receiver output values for emitter-receiver pairs that deviate significantly from corresponding receiver expected values, wherein the selected values indicate at least that light pulses transmitted by two emitters are blocked from reaching one receiver, or that light pulses transmitted by one emitter are blocked from reaching two receivers, associating a screen coordinate along a first screen axis with each selected receiver output, and calculating a touch coordinate by interpolating the associated screen coordinates according to the respective deviations between the selected receivers'"'"' output values and corresponding expected values.

Claims

1. A method of determining a touch coordinate on a touch screen, comprising:

providing (i) a display, (ii) a plurality of collimating lenses along two opposite edges of the display, the collimating lenses being arranged along the two edges so as to be shift-aligned relative to one another, (iii) a plurality of light pulse emitters that transmit light pulses through the collimating lenses of a first of the two edges over the display, and (iv) a plurality of light pulse receivers that receive the light pulses through the collimating lenses of the opposite of the two edges, and that output values representing the received light pulses, wherein light pulses emitted by each emitter are detected by at least two of the receivers, wherein each receiver detects light pulses emitted by at least two emitters, and wherein each receiver has expected values for emitter-receiver pairs when light pulses are not blocked;

selecting receiver output values for emitter-receiver pairs that deviate significantly from corresponding receiver expected values, wherein the selected values indicate at least (a) that light pulses transmitted by two emitters are blocked from reaching one receiver, or (b) that light pulses transmitted by one emitter are blocked from reaching two receivers;

associating a screen coordinate along a first screen axis with each selected receiver output; and

calculating a touch coordinate by interpolating the associated screen coordinates according to the respective deviations between the selected receivers'"'"' output values and corresponding expected values.

2. The method of claim 1, comprising further providing (v) a second plurality of collimating lenses along the other two opposite edges of the display, the second plurality of collimating lenses being arranged along the other two opposite edges so as to be shift-aligned relative to one another, (vi) a second plurality of light pulse emitters that transmit light pulses through the collimating lenses of a first of the other edges over the display, and (vii) a second plurality of light pulse receivers that receive the light pulses through the collimating lenses of the opposite of the other edges, and that output values representing the received light pulses, wherein light pulses emitted by each emitter are detected by at least two of the receivers, wherein each receiver detects light pulses emitted by at least two emitters, and wherein each receiver has expected values for emitter-receiver pairs when the light pulses are not blocked;

further selecting a receiver output value for a receiver-emitter pair, for a receiver from the second plurality of receivers, that significantly deviates from the corresponding receiver expected value;

further associating a screen coordinate along a second screen axis with the further selected receiver output value; and

further calculating each screen coordinate along the first screen axis, for each selected receiver output value, according to the intersection of a line connecting the emitter-receiver pair associated with the selected receiver output and the second screen axis coordinate.

3. The method of claim 1 wherein said selecting receiver output values comprises selecting three receiver output values for emitter-receiver pairs, which indicate that light pulses transmitted by two emitters are blocked from reaching two receivers.

4. The method of claim 3 wherein said selecting receiver output values comprises:

identifying and selecting a receiver output value for an emitter-receiver pair, which deviates from its corresponding expected value by more than receiver output values for other emitter-receiver pairs deviate from their corresponding expected values; and

further selecting a receiver output value for an emitter-receiver pair to the left of the emitter-receiver pair corresponding to the identified receiver output value, and a receiver output value for an emitter-receiver pair to the right of the emitter-receiver pair corresponding to the identified receiver output value.

5. The method of claim 4 wherein said interpolating comprises computing a weighted average of the screen coordinates according to each selected receiver output value'"'"'s deviation from its corresponding expected value.

6. The method of claim 5 wherein said calculating further comprises:

providing a reference touch coordinate; and

computing a temporally filtered touch coordinate, based on the computed weighted average and the reference touch coordinate.

7. The method of claim 6 further comprising updating the reference touch coordinate with either (i) the temporally filtered touch coordinate, or (ii) a combination of the temporally filtered touch coordinate and the reference touch coordinate.

8. A method of determining a touch coordinate on a touch screen, comprising:

providing a display, a touch detector associated with the display, the touch detector being operable to register a plurality of touch locations in response to a single touch on the display, each registered touch location having a normalized touch value between 0 and 1, and a respective screen coordinate; and

calculating a touch coordinate comprising interpolating the registered touch locations'"'"' screen coordinates according to the registered touch locations'"'"' normalized touch values.

9. The method of claim 8 further comprising:

identifying and selecting a first registered touch location whose normalized value is greater than the normalized values of other registered touch locations; and

further selecting registered touch locations that surround the first touch location, the surrounding touch locations having normalized touch values significantly greater than 0,

wherein said interpolating comprises interpolating the surrounding registered touch locations'"'"' screen coordinates according to the surrounding registered touch locations'"'"' normalized touch values.

10. The method of claim 8 wherein said interpolating comprises computing a weighted average of the screen coordinates.

11. The method of claim 8 wherein said calculating further comprises:

providing a reference touch coordinate; and

computing a temporally filtered touch coordinate, based on the calculated touch coordinate and the reference touch coordinate.

12. The method of claim 11 further comprising updating the reference touch coordinate with either (i) the temporally filtered touch coordinate, or (ii) a combination of the temporally filtered touch coordinate and the reference touch coordinate.

13. A method of pairing x- and y-coordinate values in a touch screen system in response to two simultaneous touches, comprising:

providing (i) a display, (ii) a plurality of collimating lenses along two opposite edges of the display, the collimating lenses being arranged along the two edges so as to be shift-aligned relative to one another, (iii) a plurality of light pulse emitters that transmit light pulses through the collimating lenses of one of the two edges over the display, and (iv) a plurality of light pulse receivers that receive the light pulses through the collimating lenses of the opposite of the two edges, and that output values representing the received light pulses, wherein light pulses transmitted by each emitter are detected by at least two receivers, wherein each receiver detects light pulses transmitted by at least two emitters, and wherein each receiver has expected values for emitter-receiver pairs when the light pulses are not blocked;

detecting two different x-coordinates and two different y-coordinates corresponding to two simultaneous touches, based on significant deviations between receiver output values for receiver-emitter pairs along the two opposite display edges and corresponding receiver expected values;

comparing the deviations corresponding to the x-coordinates;

pairing one of the x-coordinates with an appropriate one of the y-coordinates, based on said comparing.

14. The method of claim 13 wherein said comparing comprises comparing relative deviations.

15. The method of claim 13 wherein said comparing comprises comparing absolute deviations.

16. The method of claim 13 wherein said comparing comprises comparing patterns of emitter-receiver pairs that indicate a touch for each coordinate.

17. The method of claim 13 further comprising:

further comparing deviations corresponding to the y-coordinates; and

further pairing one of the y-coordinates with an appropriate one of the x-coordinates, based on said comparing and said further comparing.

18. A method of discriminating clockwise gestures from counter-clockwise gestures in a touch screen system, comprising:

providing (i) a display, (ii) a plurality of collimating lenses along two opposite edges of the display, the collimating lenses being arranged along the two edges so as to be shift-aligned relative to one another, (iii) a plurality of light pulse emitters that transmit light pulses through the collimating lenses of a first of the two edges over the display, and (iv) a plurality of light pulse receivers that receive the light pulses through the collimating lenses of the opposite of the two edges, and that output values representing the received light pulses, wherein light pulses transmitted by each emitter are detected by at least two receivers, wherein each receiver detects light pulses transmitted by at least two emitters, and wherein each receiver has expected values for emitter-receiver pairs when the light pulses are not blocked;

performing a series of touch detections over time, each touch detection detecting two different x-coordinates and two different y-coordinates corresponding to two touches, the touch detections being based on significant deviations between receiver output values for receiver-emitter pairs along the two opposite display edges and corresponding receiver expected values;

separately evaluating each series of deviations for the x-coordinates over time; and

discriminating a gesture as being clockwise or counter-clockwise comprising pairing one of the series of the x-coordinates with an appropriate one of the series of the y-coordinates, based on said separately evaluating.

19. The method of claim 18 wherein said separately evaluating comprises comparing relative deviations over time.

20. The method of claim 18 wherein said separately evaluating comprises comparing absolute deviations over time.

21. The method of claim 18 wherein said separately evaluating comprises comparing patterns of emitter-receiver pairs that indicate a touch over time.

22. The method of claim 21 further comprising further separately evaluating each series of deviations for the y-coordinates over time, wherein said discriminating a gesture as being clockwise or counter-clockwise further comprises pairing one of series of the y-coordinates with an appropriate one of the series of the x-coordinates, based on said further separately evaluating.