US 2025/0085448 A1 · PRECISE PROXIMITY OBJECT DETECTION FOR CAPACITIVE SENSING

Abstract

An integrated circuit includes a capacitive sensing circuit to receive signal values associated with a proximity distance to an object. A pair of low pass filters (LPFs) are coupled in parallel to the capacitive sensing circuit and include a first LPF configured with a low filtering rate and a second LPF configured with high filtering rate that is higher than that of the low filtering rate. Control logic is coupled to the pair of LPFs and estimates the proximity distance based on one or more filtered signal values received from the pair of LPFs. The logic causes the second LPF to filter the signal values while the proximity distance remains unchanged. The logic detects a change in the proximity distance beyond a threshold value. The logic causes the first LPF to filter a subsequent signal value received from the capacitive sensing circuit based on detecting the change.

Claims20

Dependent claims

An integrated circuit comprising:

a capacitive sensing circuit to receive signal values associated with a proximity distance to an object;
a pair of low pass filters (LPFs) coupled in parallel to the capacitive sensing circuit, the pair of LPFs comprising:
a first LPF configured with a low filtering rate;
and
a second LPF configured with a high filtering rate that is higher than that of the low filtering rate;
and
logic coupled to the pair of LPFs, the logic to:
estimate the proximity distance based on one or more filtered signal values received from the pair of LPFs;
cause the second LPF to filter the signal values while the proximity distance remains unchanged;
detect a change in the proximity distance beyond a threshold value;
and
cause the first LPF to filter a subsequent signal value received from the capacitive sensing circuit based on detecting the change.

9 more elements

A method comprising:

causing a capacitive sensing circuit to scan for signal values received via a sensing capacitor of a capacitive sensing system, the signal values associated with a proximity distance to an object;
determining, by processing logic of the capacitive sensing system, whether an absolute amplitude difference between a present signal value and one of a set of immediate, previously detected signal values is greater than a threshold value;
causing, in response to the absolute amplitude difference being greater than the threshold value, a bypass of filtering the present signal value to pass an unfiltered present signal value;
and
employing the unfiltered present signal value together with one or more filtered signal values to track the proximity distance to the object.

2 more elements

A method comprising:

causing a capacitive sensing circuit to scan for signal values received via a sensing capacitor of a capacitive sensing system, the signal values associated with a proximity distance to an object;
filtering the signal values through a second order Bessel filter to generate first filtered signal values;
filtering the signal values through an infinite impulse response (JIR) filter to generate second filtered signal values;
selecting, for output signal values, between respective ones of the first and second filtered values depending on whether an absolute amplitude difference between each first filtered signal value and a corresponding second filtered signal value is less than a threshold value;
and
employing the output signal values to track the proximity distance to the object.

3 more elements

Dependencies are inferred from the claim text.

Precise proximity object detection for capacitive sensing

Life of this patent

Precise proximity object detection for capacitive sensing

Life of this patent

Abstract

Claims20