Device comprising force sensors

Patent metadata

Field	Value
Publication number	US-10992297-B2
Application number	US-201916369645-A
Country	US
Kind code	B2
Filing date	Mar 29, 2019
Priority date	Mar 29, 2019
Publication date	Apr 27, 2021
Grant date	Apr 27, 2021

Abstract

A device, comprising: a pair of force sensors located for detecting a user squeeze input; and a controller operable in a squeeze detection operation to detect the user squeeze input based on a cross-correlation between respective sensor signals originating from the pair of force sensors.

First claim

The invention claimed is:

1. A device, comprising:
a pair of force sensors located for detecting a user squeeze input; and
a controller operable in a squeeze detection operation to detect the user squeeze input based on a cross-correlation between respective sensor signals originating from the pair of force sensors,
wherein at least one said pair of force sensors is part of a group of force sensors located on the device for detecting the user squeeze input corresponding to the group, wherein:
said group comprises force sensors s 1 , s 2 , s 3 and s 4 ;
the sensor signals originating from the group are digital signals s 1 ( n ), s 2 ( n ), s 3 ( n ) and s 4 ( n ) corresponding respectively to the force sensors s 1 , s 2 , s 3 and s 4 and each comprising a series of numbered samples, where n is the sample number; and
the squeeze detection operation for said group comprises calculating correlation coefficients ρ 1 (n) and ρ 2 (n) based on the equations:
ρ 1 ( n )=λ·ρ 1 ( n− 1)+(1−λ)· s 1( n )· s 2( n )

ρ 2 ( n )=λ·ρ 2 ( n− 1)+(1−λ)· s 3( n )· s 4( n )

where λ is a smoothing parameter.

2. The device as claimed in claim 1 , wherein said user squeeze input comprises a user applying forces:
with one or both of their hands; and/or
which together compress the device; and/or
at at least two different locations on the device at the same time; and/or
on at least two different sides or edges of the device at the same time; and/or
on at least two opposite or opposing sides or edges of the device at the same time.

3. The device as claimed in claim 1 , wherein said pair of force sensors are provided:
at different locations on the device; and/or
on the same side or edge of the device, or on different sides or edges of the device, or on opposite or opposing sides or edges of the device; and/or
on the device at locations according to anthropometric measurements of a human hand.

4. The device as claimed in claim 1 , wherein the squeeze detection operation comprises determining a cross-correlation value based on said sensor signals and detecting the user squeeze input based on the cross-correlation value.

5. The device as claimed in claim 4 , wherein determining the cross-correlation value comprises determining a sliding dot product, a cross-product, a product, a sum or a combination of the sensor signals originating from the pair of force sensors.

6. The device as claimed in claim 4 , wherein the respective sensor signals originating from the pair of force sensors are digital signals, and the squeeze detection operation comprises determining the cross-correlation value on a sample-by-sample basis.

7. The device as claimed in claim 6 , wherein:
for a given sample, the cross-correlation value is generated as an updated cross-correlation value by updating an existing cross-correlation value based on a new cross-correlation value determined based on the sensor signals for that sample, optionally wherein the updated cross-correlation value is based on the existing cross-correlation value to an extent defined by a smoothing parameter, or is based on a combination or sum of a proportion of the existing cross-correlation value and a proportion of the new cross-correlation value, those proportions defined by the smoothing parameter; and/or
the cross-correlation value is generated as a smoothed or averaged cross-product of the respective sensor signals originating from the pair of force sensors.

8. The device as claimed in claim 4 , wherein the squeeze detection operation comprises:
at least one of normalising, filtering and bounding the cross-correlation value; and/or
normalising the cross-correlation value to a maximum expected force value; and/or
converting the cross-correlation value into a percentage or a fraction of a defined maximum value; and/or
comparing the cross-correlation value with a threshold value.

9. The device as claimed in claim 8 , wherein the squeeze detection operation comprises determining whether the cross-correlation value exceeds the threshold value.

10. The device as claimed in claim 9 , configured to control the threshold value based on one or more of a device configuration, a device setting and a user input.

11. The device as claimed in claim 8 , wherein the squeeze detection operation comprises determining whether the cross-correlation value exceeds the threshold value for a threshold period of time, or by a threshold percentage of the threshold period of time.

12. The device as claimed in claim 1 , comprising a plurality of said pairs of force sensors, each pair located for detecting a corresponding user squeeze input, wherein:
the controller is operable, for each said pair of force sensors, to carry out a said squeeze detection operation to detect the corresponding user squeeze input.

13. The device as claimed in claim 1 , at least two said pairs of force sensors being located on the device for detecting the same user squeeze input, wherein:
the controller is operable to detect the user squeeze input corresponding to those pairs of force sensors based on a combination of the squeeze detection operations carried out for those pairs, optionally by combining cross-correlation values determined in respect of each of those pairs.

14. The device as claimed in claim 1 , at least one said pair of force sensors being part of a group of force sensors located on the device for detecting the user squeeze input corresponding to the group, wherein:
the squeeze detection operation, for said group, comprises comparing respective sensor signals originating from at least three of the force sensors of the group.

15. The device as claimed in claim 1 , wherein:
the squeeze detection operation for said group comprises normalising the correlation coefficients ρ 1 (n) and ρ 2 (n) to produce respective normalised correlation coefficients based on the equations:

ρ
~

1

⁡

(
n
)

=

min
⁡

(

max
⁡

(

ρ
1

⁡

(
n
)

,
0

)

,
γ

)

γ

ρ
~

2

⁡

(
n
)

Assignees

• Cirrus Logic Int Semiconductor Ltd
• Cirrus Logic Inc

Inventors

• Peso Parada Pablo
• Birchall Tom
• Sepehr Hamid

Classifications

• H03K17/9625 Primary

  using a force resistance transducer · CPC title

• G06F3/044

  by capacitive means · CPC title

• H03K2217/96038

  Inductive touch switches · CPC title

• G06F3/04144

  using an array of force sensing means (position sensing using the local deformation of sensor cells G06F3/0447) · CPC title

• H03K17/962

  Capacitive touch switches · CPC title