Synchronous timed orthogonal measurement pattern for multi-touch sensing on a touchpad

• US 9,058,082 B2
• Filed: 08/12/2010
• Issued: 06/16/2015
• Est. Priority Date: 08/12/2009
• Status: Active Grant

• Current Assignee: Cirque Corporation
• Original Assignee: Cirque Corporation
• Inventors: Paulsen, Keith L., Vincent, Paul, Bytheway, Jared G.
• Primary Examiner(s): BALAOING, ARIEL A
• Application Number:
  US12/855,545
• Publication Number:
  US 20110037724A1
• Time in Patent Office: 1,769 Days
• Field of Search: 345173-178, 178 1801- 1811
• US Class Current: 1/1
• 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 2203/04105 Pressure sensors for measuring the pressure or force exerted on the touch surface without providing the touch position
• 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 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

A method for detecting multiple objects on a touchpad having a grid of orthogonal electrodes, wherein all drive electrodes are simultaneously stimulated, and then frequency or electrode coding is used to separate each electrode junction and produce a capacitance image of the touchpad surface in a single measurement sequence.

Claims

1. A method for detecting the presence of multiple objects on a touchpad, said method comprising:

1) providing a touchpad with two co-planar sets of electrodes arranged as orthogonal arrays, wherein a first set of electrodes act as drive electrodes, and a second set of electrodes act as sense electrodes;

2) simultaneously stimulating all of the drive electrodes using modulated stimulus signals having arbitrary amplitudes formed by orthogonal codes that do not have phase orthogonality, wherein all permutations of orthogonal code dot products are equal to zero; and

3) receiving measurement data regarding capacitance at each electrode junction.

2. The method as defined in claim 1 wherein the method further comprises dividing each of the drive electrodes into sub-channels using sub-carriers for use with the orthogonal code sets.

3. The method as defined in claim 1 wherein the method further comprises maintaining balance on the drive electrodes by having an equal number of in-phase and out-of-phase drive electrodes.

4. The method as defined in claim 1 wherein the method further comprises processing the measurement data to thereby generate an image of all contacts on a surface of the touchpad.

5. The method as defined in claim 1 wherein the method further comprises processing the measurement data using de-convolution of a predefined transfer function to determine a location of the contacts.

6. The method as defined in claim 1 wherein the method further comprises processing the measurement data using cross correlation of a predefined transfer function to determine location of the contacts.

7. The method as defined in claim 1 wherein the method further comprises processing the measurement data using cross auto-correlation in time to determine motion of the contacts.