TOUCH SCREEN CALIBRATION AND UPDATE METHODS

• US 20110169781A1
• Filed: 03/22/2011
• Published: 07/14/2011
• Est. Priority Date: 11/04/2002
• Status: Active Grant

• Current Assignee: Neonode, Inc.
• Original Assignee: Neonode, Inc.
• Inventors: Shain, Joseph, Goertz, Magnus, Eriksson, Thomas, Pettersson, Robert, Sparf, Lars, Jansson, Anders, Karlsson, John, Kvist, Niklas
• Granted Patent: US 9,052,771 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 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• 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 calibrating optical components in a light-based touch screen, including providing (i) a display, (ii) a row of light pulse emitters that sequentially transmit light pulses over the display according to calibrated pulse current and pulse duration controls, and (iii) a row of light pulse receivers that receive the light pulses and that output values representing the received light pulses, each receiver having expected values for emitter-receiver pairs when the light pulses are not blocked, determining if each receiver output value for a receiver-emitter pair is within a respective designated range from the corresponding receiver expected value, and when a receiver output value for a receiver-emitter pair is outside the designated range, recalibrating the emitter, including adjusting at least one of the emitter pulse current and pulse duration such that subsequent receiver output values are within the designated range, and updating the receiver expected value for the receiver-emitter pair based on subsequent output values of the receiver.

Claims

1. A method of calibrating optical components in a light-based touch screen, comprising:

providing (i) a display, (ii) a row of light pulse emitters that sequentially transmit light pulses over the display according to calibrated pulse current and pulse duration controls, and (iii) a row of light pulse receivers that receive the light pulses and that output values representing the received light pulses, each receiver having expected values for emitter-receiver pairs when the light pulses are not blocked;

determining if each receiver output value for a receiver-emitter pair is within a respective designated range from the corresponding receiver expected value; and

when a receiver output value for a receiver-emitter pair is outside the designated range;

recalibrating the emitter, comprising adjusting at least one of the emitter pulse current and pulse duration such that subsequent receiver output values are within the designated range; and

updating the receiver expected value for the receiver-emitter pair based on subsequent output values of the receiver.

2. The method of claim 1 further comprising determining that light pulses are not being blocked based on the deviation between receiver output values and expected values, prior to said recalibrating.

3. The method of claim 2, wherein said determining that light pulses are not being blocked comprises comparing deviations between receiver output values for neighboring emitter-receiver pairs and corresponding receiver expected values.

4. The method of claim 1 further comprising determining that receiver output values for the emitter-receiver pair are stable over a time duration, prior to said recalibrating.

5. A method of updating receiver expected values in a light-based touch screen, comprising:

providing (i) a display, (ii) a row of light pulse emitters that sequentially transmit calibrated light pulses over the display, and (iii) a row of light pulse receivers that receive the light pulses and that output values representing the received light pulses, each receiver having expected values for emitter-receiver pairs when the light pulses are not blocked;

determining which receivers detect a touch event on the display that partially blocks the light pulses, based on deviations between receiver output values for some receiver-emitter pairs, and corresponding receiver expected values; and

updating receiver expected values for remaining receiver-emitter pairs, based on corresponding receiver output values.

6. The method of claim 5 further comprising determining that receiver output values for the remaining receiver-emitter pairs are stable over a time duration, prior to said updating.

7. The method of claim 5 further comprising determining that receiver output values for the remaining receiver-emitter pairs are within a designated range of their expected values, prior to said updating.

8. The method of claim 5, wherein said determining comprises comparing deviations between receiver output values for neighboring emitter-receiver pairs and corresponding receiver expected values.