Capacitive sensor

• US 20080127739A1
• Filed: 02/05/2008
• Published: 06/05/2008
• Est. Priority Date: 02/10/2006
• Status: Active Grant

• Current Assignee: Alfred R. Deangelis, Brian A. Mazzeo, Wilson D. Bruce
• Original Assignee: Alfred R. Deangelis, Brian A. Mazzeo, Wilson D. Bruce
• Inventors: DeAngelis, Alfred R., Mazzeo, Brian A., Wilson, D. Bruce
• Granted Patent: US 7,578,195 B2
• Time in Patent Office: Days
• US Class Current: 73/718
• CPC Class Codes: G01L 1/146 for measuring force distributions, e.g. using force arrays G01L1/148 takes precedence
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 2017/9602 characterised by the type or shape of the sensing electrodes
• CPC Class Codes: H03K 2217/96076 with spring electrode
• CPC Class Codes: Y10T 428/24917 including metal layer

Abstract

The invention relates to a flexible, resilient capacitive sensor suitable for large-scale manufacturing. The sensor comprises a dielectric, an electrically conductive layer on the first side of the dielectric layer, an electrically conductive layer on a second side of the dielectric layer, and a capacitance meter electrically connected to the two conductive layers to detect changes in capacitance upon application of a force to the detector. The conductive layers are configured to determine the position of the applied force. The sensor may be shielded to reduce the effects of outside interference.

Claims

1. A flexible capacitive sensing grid comprising:

a flexible, resilient, dielectric layer having a first and a second side;

a first conductive layer on the first side of the dielectric layer comprising at least first and second conductive elements wherein the first conductive element is electrically isolated from second conductive element; and

,

a second conductive layer on the second side of the dielectric layer comprising at least third and fourth conductive elements wherein the third conductive element is electrically isolated from the fourth conductive element and wherein the third element at least partially overlaps the first and second elements and the fourth element at least partially overlaps the first and second elements, and wherein the third and forth elements are electrically separated from the first and second elements by the flexible, resilient, dielectric layer.

2. The flexible capacitive sensing grid of claim 1, further comprising a capacitance meter electrically connected to each conductive element.

3. The flexible capacitive sensing grid of claim 1, wherein the conductive elements have an aspect ratio of greater than 5:

1.

4. The flexible capacitive sensing grid of claim 1, wherein the third conductive element crosses the first and second conductive elements at an angle of between 5 and 175 degrees.

5. The flexible capacitive sensing grid of claim 4, wherein the fourth conductive element crosses the first and second conductive elements at an angle of between 5 and 175 degrees.

6. The flexible capacitive sensing grid of claim 1, wherein the conductive elements form a grid.

7. The flexible capacitive sensing grid of claim 1, wherein the sensing grid further comprises at least one cover layer on the first conductive layer on the side opposite the dielectric.

8. The flexible capacitive sensing grid of claim 7, wherein the cover layer comprises fabric.

9. The flexible capacitive sensing grid of claim 1, wherein each of the conductive elements each have a resistance of 1 megaohm or less.

10. The flexible capacitive sensing grid of claim 1, wherein the resistance measured between the first and second conductive layers is 10⁹ ohms or greater.

11. The flexible capacitive sensing grid of claim 1, wherein the dielectric layer comprises a spacer fabric.

12. A flexible capacitive sensing grid comprising:

a flexible, resilient, dielectric layer having a first and a second side;

a first conductive layer on the first side of the dielectric layer comprising at least first and second conductive elements wherein the first conductive element is electrically isolated from second conductive element;

a second conductive layer on the second side of the dielectric layer comprising at least a third conductive element;

a second resilient, dielectric layer attached on its first side to the second conductive layer; and

,

a third conductive layer comprising at least fourth and fifth conductive elements on the second side of the second resilient dielectric layer, wherein the fourth conductive element is electrically isolated from fifth conductive element, and wherein the first, second, fourth and fifth conductive elements form a grid and the third conductive element is located at least where the first and second conductive elements overlap the fourth and fifth conductive elements.

13. The flexible capacitive sensing grid of claim 12, further comprising a capacitance meter electrically connected to each conductive element.