US 9,753,586 B2Granted

Multi-touch touch device with multiple drive frequencies and maximum likelihood estimation

Assignee3M Innovative Properties Company

InventorsRachael P. Marino, Richard A. Peterson, Jr.

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Abstract

A touch-sensitive device includes a touch panel, drive unit, and measurement unit. A touch applied to a given node of the panel changes a capacitive coupling between a given drive and sense electrode of the touch panel. The drive unit delivers first and second drive signals, having different first and second frequencies, to first and second drive electrodes respectively at the same or overlapping times. The measurement unit receives a first response signal from a sense electrode, and analyzes the signal using maximum likelihood estimation to determine the coupling capacitance between the first drive electrode and the sense electrode, and between the second drive electrode and the sense electrode. More drive electrodes, including in some cases all the drive electrodes, can be driven with unique drive frequencies, and more sense electrodes, including in some cases all the sense electrodes, can be sensed by the measurement unit.

Claims20

Dependent claims

A touch-sensitive apparatus, comprising:

a panel comprising a touch surface, a plurality of drive electrodes, and a plurality of receive electrodes;
a drive unit configured to deliver a first drive signal having a first drive frequency to a first one of the drive electrodes while also delivering a second drive signal having a second drive frequency, different from the first drive frequency, to a second one of the plurality of drive electrodes;
and
a measurement unit configured to receive a first response signal from a first one of the plurality of receive electrodes, and to analyze the first response signal to determine therefrom (a) a first coupling capacitance between the first receive electrode and the first drive electrode using a maximum likelihood estimation for a square of a first amplitude at a first frequency associated with the first drive frequency using a probability density function of the first amplitude and at least one amplitude of the first response signal, and (b) a second coupling capacitance between the first receive electrode and the second drive electrode using a maximum likelihood estimation for a square of a second amplitude at a second frequency associated with the second drive frequency using a probability density function of the second amplitude and the at least one amplitude of the first response signal.

1 more element

A method of determining a plurality of touch locations for touches on a touch panel that are simultaneous or overlapping in time, the method comprising:

providing a panel comprising a touch surface, a plurality of drive electrodes, and a plurality of receive electrodes;
delivering a first drive signal having a first drive frequency to a first one of the drive electrodes while also delivering a second drive signal having a second drive frequency, different from the first drive frequency, to a second one of the plurality of drive electrodes;
receiving a first response signal from a first one of the plurality of receive electrodes;
analyzing the first response signal to determine therefrom (a) a first coupling capacitance between the first receive electrode and the first drive electrode using a maximum likelihood estimation of a square of a first amplitude at a first frequency associated with the first drive frequency using a probability density function of the first amplitude and at least one amplitude of the first response signal, and (b) a second coupling capacitance between the first receive electrode and the second drive electrode using a maximum likelihood estimation of a square of a second amplitude at a second frequency associated with the second drive frequency using a probability density function of the second amplitude and the at least one amplitude of the first response signal.

1 more element

Dependencies are inferred from the claim text.

Facts

Application: 12/575,860Filed 8 Oct 2009
Published: US 2011/0084857 A114 Apr 2011
Granted: 5 Sep 2017
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

G06F 3/0445
By capacitive means: using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
G06F 3/04182
For error correction or compensation, e.g. based on parallax, calibration or alignment: filtering of noise external to the device and not…
G06F 3/0446
By capacitive means: using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
G06F
Computing and data processing