Capacitive sensor to detect a finger for a control or command operation

• US 20070114073A1
• Filed: 10/24/2006
• Published: 05/24/2007
• Est. Priority Date: 10/28/2005
• Status: Abandoned Application

• Current Assignee: Jaeger Controls
• Original Assignee: Jaeger Controls
• Inventors: Akel, Dominique, Lomp, Stephane
• Application Number:
  US11/585,452
• Publication Number:
  US 20070114073A1
• Time in Patent Office: Days
• US Class Current: 178/18.60
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes

Abstract

A capacitive sensor to detect a finger for an operation of a control and/or command comprises an electrically insulating layer forming a detection surface fitted with position marks for application of a finger, and generation of a signal by positioning or movement of the finger. A capacitive layer is covered by an insulating layer and formed by a stack of alternating conductive sections and non-conductive sections placed on edge. At least some conductive layers are linked to elementary contacts to form parts of capacitors distributed in cells. The capacitance of all capacitors of a cell is added together in the signal supplied by the cell. A processing circuit linked to the cell connectors of the capacitive cells receives the capacitive signals to evaluate and compare them, and to establish whether they correspond to the presence of a finger, and to determine the nature of the finger.

Claims

1. Capacitive sensor to detect a finger for operation of a control or command, comprising

A) an electrical insulating layer forming a detection surface fitted with position references for application of a finger and generation of a signal by positioning or movement of the finger,

B) a capacitive layer covered by the insulating layer and formed by a stack of alternating conductive sections and non-conductive sections placed on edge, at least some of the conductive layers being linked to elementary contacts to form parts of capacitors distributed in cells, the elementary contacts being connected in parallel to a cell connector, a part of the elementary capacitor being completed by the surface of the finger applied to the insulating layer to form a capacitor, the capacitance of all capacitors of a cell being added together in the signal supplied by the cell,

C) a processing circuit to which are linked the cell connectors of the capacitive cells and which receives the capacitive signals to evaluate and compare them and to establish whether they correspond to the presence of a finger, and to determine the nature of the finger.

2. Capacitive sensor according to claim 1, wherein the processing circuit uses only signals from adjacent cells.

3. Capacitive sensor according to claim 1, wherein the electrical insulating layer comprises a plate of glass or a layer of an electrically insulating material.

4. Capacitive sensor according to claim 1, wherein the stack of alternating conductive sections and nonconductive sections of the capacitive layer forming the connection element comprises an elastomer segmented by conductive sections.

5. Capacitive sensor according to claim 1, wherein the elementary contacts are merged in the cell connector which covers and touches a succession of conductive layers of a cell.

6. Capacitive sensor according to claim 5, wherein the cell connector has a longitudinal extension and a transverse extension in a cell.

7. Capacitive sensor according to claim 5, wherein the cell connectors are identical.

8. Capacitive sensor according to claim 5, wherein the cell connectors have an identical surface area.