Proximity sensor with nonlinear filter and method

• US 10,298,280 B2
• Filed: 04/25/2018
• Issued: 05/21/2019
• Est. Priority Date: 05/12/2017
• Status: Active Grant

• Current Assignee: Semtech Corporation
• Original Assignee: Semtech Corporation
• Inventors: Nys, Olivier, Rouaissia, Chaouki
• Primary Examiner(s): Bilgrami, Asghar H
• Application Number:
  US15/962,761
• Publication Number:
  US 20180331706A1
• Time in Patent Office: 391 Days
• CPC Class Codes: G01V 3/08 operating with magnetic or electric fields produced or modified by objects or geological structures or by detecting devices with electromagnetic waves G01V3/12
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: H03K 17/955 using a capacitive detector
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• CPC Class Codes: H04B 1/3838 Arrangements for reducing RF exposure to the user, e.g. by changing the shape of the transceiver while in use
• CPC Class Codes: H04M 2250/12 including a sensor for measuring a physical value, e.g. temperature or motion

Abstract

A sensor for a portable connected device comprising a filter 30 is arranged to reduce a noise component on a sampled input signal, wherein the filter is arranged to consider only input measurements that change systematically in a same direction, updating an output value when all the input samples in a predetermined time window are above or below a current output value and, repeating the current output value when the input samples in the time window are below and above the current output value.

Claims

1. A sensor for a portable connected device comprising a filter is arranged to reduce a noise component on a sampled input signal, wherein the filter is arranged to consider only input measurements that change systematically in a same direction, updating an output value when all the input samples in a predetermined time window are above or below a current output value and, repeating the current output value when the input samples in the time window are below and above the current output value.

2. The sensor of claim 1 wherein the filter is arranged to set the output value to the minimum or to the maximum of the input samples in the time window when all the input samples in the time window are below, respectively above the current output value.

3. The sensor of claim 1, wherein the filter is arranged to shift the output value towards the minimum or the maximum of the input samples in the time window when all the input samples in the time window are below, respectively above the current output value.

4. The sensor of claim 1, the filter being arranged to compare the average change in the input signal with an expected spread of the measurement, and update the output value only when the average change is larger than a predetermined fraction of the expected spread.

5. The sensor of claim 1, comprising a linear low-pass filter.

6. The sensor of claim 1, comprising a baseline correction unit and a discriminator.

7. The sensor of claim 1 being a capacitive proximity sensor arranged to determine whether a user is in proximity to the portable connected device based on a capacity seen by a sense electrode.

8. A portable connected device comprising capacitive proximity sensor arranged to determine whether a user is in proximity to the portable connected device based on a capacity seen by a sense electrode, comprising a filter is arranged to reduce a noise component on a sampled input signal, wherein the filter is arranged to consider only input measurements that change systematically in a same direction, updating an output value when all the input samples in a predetermined time window are above or below a current output value and, repeating the current output value when the input samples in the time window are below and above the current output value, the connected device being operatively arranged to adapt a RF power of a radio transmitter based on the proximity of a user to the portable connected device.

9. The portable connected device of claim 8, wherein the sense electrode is also an emitter of radio waves.