SYNCHRONOUS TIMED ORTHOGONAL MEASUREMENT PATTERN FOR MULTI-TOUCH SENSING ON A TOUCHPAD

• US 20110037724A1
• Filed: 08/12/2010
• Published: 02/17/2011
• Est. Priority Date: 08/12/2009
• Status: Active Grant

• Current Assignee: Cirque Corporation
• Original Assignee: Cirque Corporation
• Inventors: Vincent, Paul, Paulsen, Keith L., Bytheway, Jared G.
• Granted Patent: US 9,058,082 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• 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 the steps of:

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 a coded pattern of stimulus signals;

3) receiving data regarding capacitance at each electrode junction;

4) generating raw image data of a surface of the touchpad from the data; and

5) processing the raw image data to thereby extract contact information that is used to generate an image of all objects touching a surface of the touchpad.

2. The method as defined in claim 1 wherein the step of receiving data regarding capacitance at each electrode junction further comprises the step of using the principle of mathematical orthogonality to separate measurement information from the data.

3. The method as defined in claim 2 wherein the step of using the principle of orthogonality further comprises the step of separating data that is multiplexed together.

4. The method as defined in claim 2 wherein the step of stimulating the drive electrodes further comprises the step of using code division multiple access (CDMA) to generate data than can be separated out to identify capacitance at each electrode unction.

5. The method as defined in claim 4 wherein the step of using CDMA further comprises the step of using CDMA coding to identify an electrode or an electrode junction on an electrode.

6. The method as defined in claim 2 wherein the step of stimulating the drive electrodes further comprises the step of using frequency-division multiple access (FDMA) to generate data that can be separated out to identify capacitance at each electrode junction.

7. The method as defined in claim 6 wherein the method further comprises the step of dividing each of the drive electrodes into sub-channels using sub-carriers, wherein orthogonal sub-carrier frequencies are multiples of each other.

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

9. The method as defined in claim 9 wherein the step of balancing further comprises the step of reducing the dynamic range of sense signals without reducing the amount of modulation of a contact.