Capacitive sensor for sensing tactile and proximity, and a sensing system using the same

• US 20080174321A1
• Filed: 01/19/2007
• Published: 07/24/2008
• Est. Priority Date: 01/19/2007
• Status: Active Grant

• Current Assignee: Korea Advanced Institute of Science and Technology, Regents of The University of Minnesota (University of Minnesota)
• Original Assignee: Regents of The University of Minnesota (University of Minnesota)
• Inventors: Lee, Hyung-Kyu, Kim, Munsang, Yoon, Euisik, Chang, Sun-Il, Kang, Sungchul, Choi, Junho
• Granted Patent: US 7,679,376 B2
• Time in Patent Office: Days
• US Class Current: 324/686
• CPC Class Codes: G06F 2203/04108 Touchless 2D- digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface without distance measurement in the Z direction
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• 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

Abstract

Disclosed is a capacitive proximity sensor in dual implementation. The sensor comprises an upper electrode layer having a plurality of electrodes disposed in line with each other, a lower electrode layer having a plurality of electrodes disposed in line with each other and an insulating layer disposed between the upper electrode layer and the lower electrode layer. The sensor detects the proximity of approaching objects by the capacitance change between the electrodes disposed in the upper electrode layer, and detects the contact of any objects by the capacitance change between the electrodes of the upper electrode layer and the electrodes of the lower electrode layer.

Claims

1. A capacitive sensor comprising

an upper electrode layer wherein a plurality of electrodes are disposed in line with each other;

a lower electrode layer wherein a plurality of electrodes are disposed in line with each other; and

an insulating layer disposed between said upper electrode layer and said lower electrode layer,

the capacitive sensor detecting the proximity of approaching objects by the capacitance change between the electrodes of the upper electrode layer, and detecting the contact of any object by the capacitance change between the electrode of the upper electrode layer and the electrode of the lower electrode layer.

2. The capacitive sensor of claim 1, wherein the electrodes of the upper electrode layer and the electrodes of the lower electrode layer are configured to be crossed at a certain angle.

3. The capacitive sensor of claim 2, wherein the electrodes of the upper electrode layer and the electrodes of the lower electrode layer are configured to be crossed at right angles.

4. The capacitive sensor of claim 2, wherein a layer of bumps made of insulating material is formed above the area where the electrodes of the upper electrode layer and the electrodes of the lower electrode layer are crossed.

5. The capacitive sensor of claim 5, wherein said insulating layer is made of compressible material.

6. A sensing system comprising:

a capacitive sensor comprising an upper electrode layer having a plurality of electrodes disposed in line with each other, a lower electrode layer having a plurality of electrodes disposed in line with each other, and an insulating layer disposed between said upper electrode layer and said lower electrode layer;

a proximity detection circuit wherein the electrodes of said upper electrode layer are classified into two groups, each of which is electrically connected to the proximity detection circuit, the proximity detection circuit detecting the proximity of approaching objects by the capacitance change between the two groups of electrodes; and

a tactile detection circuit electrically connected to each of the electrodes of the upper electrode layer and the lower electrode layer, the tactile detecting circuit detecting the contact of any object by the capacitance change between the electrodes of the upper electrode layer and the lower electrode layer.

7. The sensing system of claim 6,

wherein the two groups of electrodes of the upper electrode layer are each connected to the proximity detection circuit by switch unit 1;

wherein the electrodes of the upper electrode layer and the electrodes of the lower electrode layer are each connected to the tactile detection circuit by switch unit 2; and

further comprising a control unit which controls the operation of said switch unit 1 and switch unit 2.

8. The sensing system of claim 7,

wherein said control unit turns on the switch unit 1, and turns off the switch unit 2, thereby causing the sensing system to detect the proximity of the approaching object using the proximity detection circuit, and

wherein said control unit turns off the switch unit 1, and turns on the switch unit 2 when the distance to the approaching object detected by the proximity detection circuit is zero, thereby causing the sensing system to detect the contact of the object using the tactile detection circuit.

9. The sensing system of claim 6, wherein the electrodes of the upper electrode layer are classified into group 1 and group 2, wherein

the group 1 consists of electrodes disposed to the left of the center of the upper electrode layer, and the group 2 consists of the remaining electrodes;

or

the group 1 consists of the electrodes disposed at the left and right ends of the upper electrode layer, and the group 2 consists of the remaining electrodes;

or

the group 1 consists of electrodes designated an odd number and the group 2 consists of those designated an even number when the electrodes of the upper electrode layer are each designated a number in the order disposed starting from the left end.

10. The sensing system of claim 6, wherein the electrodes of the upper electrode layer and the electrodes of the lower electrode layer are configured to be crossed at a certain angle.

11. The sensing system of claim 10, wherein the electrodes of the upper electrode layer and the electrodes of the lower electrode layer are configured to be crossed at right angles.

12. The sensing system of claim 10, wherein a layer of bumps made of insulating material is formed above the area where the electrodes of the upper electrode layer and the lower electrode layer are crossed.

13. The sensing system of claim 10, wherein said insulating layer is made of compressible material.

14. The sensing system of claim 7,

wherein said control unit turns on the switch unit 1, and turns off the switch unit 2, thereby causing the sensing system to operate in a proximity detecting mode to detect the proximity of approaching objects using the proximity detection circuit, or

said control unit turns off the switch unit 1, and turns on the switch unit 2, causing the sensing system to operate in a tactile detecting mode to detect the contact of objects using the tactile detection circuit;

and

said control unit controls the operation of the switch unit 1 and the switch unit 2 so that the system would operate in the proximity detecting mode and the tactile detecting mode in alternation when the object detected by the proximity detecting circuit approaches within a predetermined distance.