Device comprising force sensors

Patent metadata

Field	Value
Publication number	US-11515875-B2
Application number	US-202117192632-A
Country	US
Kind code	B2
Filing date	Mar 4, 2021
Priority date	Mar 29, 2019
Publication date	Nov 29, 2022
Grant date	Nov 29, 2022

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:
first and second force sensors located on respective different sides or edges of the device from one another, the first and second force sensors being different force sensors from one another, said different sides or edges opposing one another such that when a user applies forces on said different sides or edges of the device at the same time said forces oppose one another and together compress the device, and a user squeeze input comprising the user applying said forces; and
a controller configured in a squeeze detection operation to detect the user squeeze input, the squeeze detection operation comprising determining a cross-correlation value of a cross-correlation between a first sensor signal originating from the first force sensor and a second sensor signal originating from the second force sensor and comparing the cross-correlation value with a threshold value.

2. The device as claimed in claim 1 , wherein said user squeeze input comprises the user applying said forces with one or both of their hands.

3. The device as claimed in claim 1 , wherein said first and second force sensors are provided on the device at locations according to anthropometric measurements of a human hand.

4. The device as claimed in claim 1 , 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 first and second force sensors.

5. The device as claimed in claim 1 , wherein the respective sensor signals originating from the first and second force sensors are digital signals, and the squeeze detection operation comprises determining the cross-correlation value on a sample-by-sample basis.

6. The device as claimed in claim 5 , 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 given 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 first and second force sensors.

7. The device as claimed in claim 1 , 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.

8. The device as claimed in claim 7 , wherein the squeeze detection operation comprises determining whether the cross-correlation value exceeds the threshold value,
optionally wherein the device is configured to control the threshold value based on one or more of a device configuration, a device setting and a user input.

9. The device as claimed in claim 7 , 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.

10. The device as claimed in claim 1 , comprising a plurality of pairs of force sensors, one of said pairs comprising said first and second 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.

11. The device as claimed in claim 1 , wherein the first and second force sensors are a pair of force sensors, and wherein at least two said pairs of force sensors are 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.

12. The device as claimed in claim 1 , the first and second force sensors being part of a group of force sensors located on the device for detecting a user squeeze input corresponding to that 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.

13. The device as claimed in claim 1 , said first and second force sensors being part of a group of force sensors located on the device for detecting a user squeeze input corresponding to that group, wherein:
said group comprises force sensors s1, s2, s3 and s4;
the sensor signals originating from the group are digital signals s1(n), s2(n), s3(n) and s4(n) corresponding respectively to the force sensors s1, s2, s3 and s4 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.

14. The device as claimed in claim 13 , 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

• G06F3/04144

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

• H03K17/9622

  using a plurality of detectors, e.g. keyboard · CPC title

• H03K17/9625 Primary

  using a force resistance transducer · CPC title

• G06F3/044

  by capacitive means · CPC title

• H03K17/962

  Capacitive touch switches · CPC title