Touch surface with hybrid touch detection

Patent metadata

Field	Value
Publication number	US-11182011-B2
Application number	US-202016898310-A
Country	US
Kind code	B2
Filing date	Jun 10, 2020
Priority date	Jun 27, 2019
Publication date	Nov 23, 2021
Grant date	Nov 23, 2021

Abstract

A touch surface includes an array of rows of electrodes, an input point on a row for injecting an input voltage (VDRIVE), measuring an output voltage (VSENSE) at a second point in the row, p being the number of pitch spacings of the array separating the two points, the portion of the array between the first point and the second point being akin to an electric dipole of resistance (R(p)) and of capacitance (C), the output voltage (VSENSE) being equal to the product of the input voltage (VDRIVE) and a transfer function represented by a complex function (HSENSE). The measurement includes extracting the amplitude (G) and the phase (φ) from the transfer function; and calculating a hybrid function (S(G, φ)) of the amplitude and of the phase, the hybrid function minimizing a sum (Σ) defined byΣi∈[0,p]⁡(δ⁢⁢Sδ⁢⁢R⁢(G⁡(Ri),φ⁡(Ri))).

First claim

The invention claimed is:

1. A touch surface comprising:
an array of rows of electrodes,
an input point on a row for injecting at least one sinusoidal input voltage (V DRIVE ) transmitted at a determined frequency and of known amplitude and phase,
a measurement device configured to measure an output voltage (V SENSE ) at a second point in said row, p denoting a minimum number of pitch spacings of the array separating a first point from the second point, a portion of the array between the first point and the second point being characterized as an electric dipole of resistance (R(p)) and of capacitance (C), the output voltage (V SENSE ) being equal to a product of the input voltage (V DRIVE ) and a complex transfer function represented by a complex function (H SENSE ),
wherein said measurement device includes electronic means for extracting a gain (G) and a phase (φ) from the complex transfer function,
wherein said measurement device being further configured to calculate a hybrid function (S(G, φ)) of said amplitude and of said phase, said hybrid function minimizing a sum (Σ) as defined by Equation (1):

Σ

i
∈

[

0
,
p

]

⁡

(

δ
⁢

⁢
S

δ
⁢

⁢
R

⁢

(

G
⁡

(

R
i

)

,

φ
⁡

(

R
i

)

)

)

Equation
⁢

⁢
1

S(G(R i ),φ(R i )) corresponding to a touch at the point i on the row; and

wherein said measurement device being further configured to determine, from a value of the hybrid function (S), whether the value is representative of a touch on the second point on the touch surface.

2. The touch surface according to claim 1 , wherein:
a change in the complex function (H SENSE ) in a complex plane being characterized as an ellipse of eccentricity (e), and
the hybrid function (S(G, φ)) is equal to the product of the amplitude G and a function k(φ) as defined by Equation (2):

k
⁡

(
φ
)

=

1
+

e
2

1
-

e
2

⁢

sin
2

⁢

⁢
φ

.

Equation
⁢

⁢
2

3. The touch surface according to claim 1 , wherein the electronic extraction means includes:
a generator of two digital signals transmitted at the same frequency as the input voltage, the two signals being in quadrature;
an analogue-to-digital converter of the output voltage delivering a sampled digital voltage;
two multipliers for multiplying the sampled digital voltage by each of the two digital signals in quadrature; and
two integrators for integrating, over a number of periods greater than one, the two signals from the two multipliers,
wherein said measurement device being further configured to calculate, on a basis of the preceding two integrated signals, to calculate the gain (G) and the phase (φ) of the transfer function.

4. The touch surface according to claim 1 , wherein the measurement device includes an electronic filter configured to filter the hybrid function (S(G, φ)).

5. A touch surface comprising:
an array of rows of electrodes,
an input point on a row for injecting at least one sinusoidal input voltage (V DRIVE ) transmitted at a determined frequency and of known amplitude and phase,
a measurement device configured to measure an output voltage (V SENSE ) at a second point in said row, p denoting a minimum number of pitch spacings of the array separating a first point from the second point, a portion of the array between the first point and the second point being characterized as an electric dipole of resistance (R(p)) and of capacitance (C), the output voltage (V SENSE ) being equal to a product of the input voltage (V DRIVE ) and a complex transfer function represented by a comp

Assignees

• Thales Sa

Inventors

• Coni Philippe
• Renaud Frédéric
• Abadie Jean-Christophe
• Rouzes Siegfried

Classifications

• G06F3/0446

  using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes · CPC title

• G06F3/0416 Primary

  Control or interface arrangements specially adapted for digitisers · CPC title

• G06F3/044

  by capacitive means · CPC title

• G06F3/0418 Primary

  for error correction or compensation, e.g. based on parallax, calibration or alignment · CPC title

• G06F3/045

  using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact · CPC title