Signal processing for a capacitive sensor system with robustness to noise
First Claim
Patent Images
1. A capacitive sensor, comprising:
- a transmit electrode configured to provide an alternating electric field for the capacitive sensor;
an oscillator generating a carrier signal;
one or more receive electrodes configured to detect variations in the alternating electric field;
an adaptive frequency adjustment unit coupled with the oscillator and configured to adjust an operating frequency of the alternating electric field responsive to detection of noise, wherein the carrier signal is modulated by an object entering the alternating electric field using amplitude modulation; and
an analog-to-digital converter configured to sample signals received from the one or more receive electrodes, wherein sampling is synchronized with the oscillator.
5 Assignments
0 Petitions
Accused Products
Abstract
A capacitive sensor includes a transmit electrode configured to provide an alternating electric field to a sensor; one or more receive electrodes for detecting variations in the alternating electric field; and an adaptive frequency adjustment unit configured to adjust an operating frequency of the alternating electric field responsive to detection of a noise measure, such as noise power.
-
Citations
23 Claims
-
1. A capacitive sensor, comprising:
-
a transmit electrode configured to provide an alternating electric field for the capacitive sensor; an oscillator generating a carrier signal; one or more receive electrodes configured to detect variations in the alternating electric field; an adaptive frequency adjustment unit coupled with the oscillator and configured to adjust an operating frequency of the alternating electric field responsive to detection of noise, wherein the carrier signal is modulated by an object entering the alternating electric field using amplitude modulation; and an analog-to-digital converter configured to sample signals received from the one or more receive electrodes, wherein sampling is synchronized with the oscillator. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
-
-
13. A method for providing noise robustness to a capacitive sensing system, comprising:
-
defining a plurality of potential operating transmit frequencies; generating a carrier signal using one of the potential operating transmit frequencies; operating the capacitive sensing system at the one of the plurality of potential operating transmit frequencies by feeding the carrier signal to a transmitting electrode thereby generating an alternating electric field; modulating the alternating electric field by an object entering the electric field using amplitude modulation; sampling signals received from the one or more receive electrodes, wherein sampling is synchronized with a selected operating transmit frequency; performing an operating noise measurement at the operating frequency; and selecting a new operating frequency responsive to a value of a measured operating noise. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
-
Specification