CAPACITIVE SENSING SYSTEM

• US 20120062253A1
• Filed: 05/31/2010
• Published: 03/15/2012
• Est. Priority Date: 06/05/2009
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Meftah, Mohammed, Feddes, Bastiaan
• Granted Patent: US 8,847,613 B2
• Time in Patent Office: Days
• US Class Current: 324/686
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/1126 using a particular sensing technique
• CPC Class Codes: A61B 5/113 occurring during breathing
• CPC Class Codes: A61B 5/6804 Garments; Clothes
• CPC Class Codes: A61B 5/6887 mounted on external non-worn devices, e.g. non-medical devices

Abstract

The invention relates to capacitive sensing system (1) for sensing an object. The capacitive sensing system (1) comprises an electrical charge providing unit (4) like an electret foil for providing a permanent electrical charge at a sensing site (6) of the object (3) and a capacitive sensor (2) comprising a sensing electrode (5) for generating a sensing signal by capacitively sensing the object (3) at the sensing site (6) of the object (3). By providing a permanent electrical charge at the sensing site (6) of the object (3), the bias between the object (3) and the sensing electrode (5) of the capacitive sensor (2) is intentionally preferentially made large, thereby increasing the sensitivity towards mechanical motions. The resulting sensing signal substantially caused by these mechanical motions between the object (3) and the sensing electrode (5) is generally larger than a signal generated substantially by an electrophysiological field.

Claims

1. A capacitive sensing system for sensing an object, the capacitive sensing system comprising:

an electrical charge providing unit for providing a permanent electrical charge at a sensing site of the object,

a capacitive sensor comprising a sensing electrode for generating a sensing signal by capacitively sensing the object at the sensing site of the object.

2. The capacitive sensing system as defined in claim 1, wherein the electrical charge providing unit comprises an electret for being attached to the object for providing the electrical charge.

3. The capacitive sensing system as defined in claim 1, wherein the electrical charge providing unit comprises a voltage source and an electrically conducting element for being attached to the object, wherein the voltage source is connected to the electrically conducting element for providing the permanent electrical charge.

4. The capacitive sensing system as defined in claim 1, wherein the capacitive sensing system further comprises a property determination unit for determining a property of the object from the generated sensing signal.

6. A computer program for sensing an object, the computer program comprising program code means for causing a capacitive sensing apparatus as defined in claim 4 to carry out following steps:

generating a sensing signal by capacitively sensing the object at a sensing site of the object, at which a permanent electrical charge is provided by an electrical charge providing unit, by a sensing electrode of a capacitive sensor,

determining a property of the object from the generated sensing signal by a property determination unit,

when the computer program is run on a computer controlling the capacitive sensing apparatus.

5. A capacitive sensing method for sensing an object, the capacitive sensing method comprising the steps of:

providing a permanent electrical charge at a sensing site of the object by an electrical charge providing unit,

generating a sensing signal by capacitively sensing the object at the sensing site of the object by a sensing electrode of a capacitive sensor.