# US 8,570,054 B2 · Device for detecting a capacitance variation and capacitive sensor for detecting the presence of a user using such a device

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- Number: US 8,570,054 B2
- Document ID: US8570054B2
- Status: Granted
- Kind: B2
- Application number: 11/916,253
- Filed: 2006-05-30
- Published: 2010-09-16
- Granted: 2013-10-29
- Earliest claimed: 2005-06-01
- Assignees: Valeo Securite Habitacle
- Applicants: Xavier Hourne
- Inventors: Xavier Hourne
- Web page: https://patentgrep.com/patent/US8570054B2

## CPC

- G01R 27/2605: {Measuring capacitance (capacitive sensors G01D5/24)}
- G01D 5/2405: {by varying dielectric}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR

## Abstract

A device for detecting a variation in the capacitance of a variable capacitive structure, wherein the device generates voltage pulses, charges the variable capacitive structure using the voltage pulses, discharges the variable capacitive structure toward a reference capacitor, detects a voltage threshold across the terminals of the reference capacitor, determines a number of charges and/or discharges of the variable capacitive structure corresponding to the voltage threshold, and detects a variation in the number of charges and/or discharges with respect to a number of charges and/or discharges previously obtained.

## Claims

### Claim 1

A user presence detection device, integrated in a motor vehicle, for detecting a variation in the capacitance of a variable capacitive structure (Cx), comprising:
a generator for generating voltage pulses;
a capacitor for charging the variable capacitive structure by means of said voltage pulses;
a resistor for discharging said variable capacitive structure toward a reference capacitor;
a comparator for detecting a voltage threshold across the terminals of the reference capacitor;
a counter for determining a number of charges and discharges of said variable capacitive structure corresponding to said voltage threshold; and
an ECU for detecting a variation in said number of charges and discharges with respect to a number of charges and discharges previously obtained.

### Claim 2 (depends on 1)

The device as claimed in claim 1, further comprising:
a diode for providing a unidirectional transfer of energy from the variable capacitive structure toward the reference capacitor.

### Claim 3 (depends on 1)

The device as claimed in claim 1, wherein the pulse generation is performed using a clock.

### Claim 4 (depends on 1)

The device as claimed in claim 1, wherein the pulse generation is performed using a high-pass filter.

### Claim 5 (depends on 1)

The device as claimed in claim 1, wherein the resistor has a value such that the time constant is greater than a duration of the voltage pulses and less than a half-period of the pulses.

### Claim 6 (depends on 1)

The device as claimed in claim 1, wherein the reference capacitor has a higher capacitance than that of the variable capacitive structure.

### Claim 7 (depends on 1)

The device as claimed in claim 1, further comprising:
a switch, controlled for discharging the reference capacitor, once the voltage across the terminals of the reference capacitor has reached a predetermined voltage threshold.

### Claim 8 (depends on 1)

A capacitive sensor for detecting the presence of a user of a piece of equipment, implementing a detection device as claimed in claim 1, wherein the capacitive structure whose capacitance variation is detected comprises a detection electrode disposed within said piece of equipment, wherein the capacitance of the capacitive structure is determined between said detection electrode and an environment near said detection electrode.

### Claim 9 (depends on 8)

The capacitive structure as claimed in claim 8, wherein a door handle of a vehicle is present at the piece of equipment within which the detection electrode is disposed.

### Claim 10 (depends on 1, 9)

The capacitive structure as claimed in claim 9, wherein the detection device as claimed in claim 1 is integrated into the door handle.