Capacitive sensor and detection method using the same

• US 9,229,551 B2
• Filed: 01/06/2012
• Issued: 01/05/2016
• Est. Priority Date: 01/07/2011
• Status: Active Grant

• Current Assignee: eGalax_eMPIA Technology Inc.
• Original Assignee: eGalax_eMPIA Technology Inc.
• Inventors: Lee, Cheng-Han
• Primary Examiner(s): HOFFNER, LINH NGUYEN
• Application Number:
  US13/344,745
• Publication Number:
  US 20120176338A1
• Time in Patent Office: 1,460 Days
• Field of Search: 345/173, 345/174, 178/18.06, 200/600
• US Class Current: 1/1
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 2203/04106 Multi-sensing digitiser, i.e. digitiser using at least two different sensing technologies simultaneously or alternatively, e.g. for detecting pen and finger, for saving power or for improving position detection
• CPC Class Codes: G06F 2203/04112 Electrode mesh in capacitive digitiser: electrode for touch sensing is formed of a mesh of very fine, normally metallic, interconnected lines that are almost invisible to see. This provides a quite large but transparent electrode surface, without need for ITO or similar transparent conductive material
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• 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 3/04186 Touch location disambiguation
• 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: G06F 3/047 using sets of wires, e.g. crossed wires
• CPC Class Codes: H03K 17/962 Capacitive touch switches
• 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

Abstract

The present invention provides a capacitive sensor and detection method using the same. The capacitive sensor of the present invention includes at least one detecting plate and at least one reference plate surrounding each detecting plate. All of the reference plates are electrically coupled to the same first wire, and each reference plate is electrically coupled to a second wire. When an electrical signal is provided to the first wire and each second wire, one or more detecting plates touched or approached can be detected simultaneously based on the signal difference between each second wire and the first wire.

Claims

1. A capacitive sensor, comprising:

a first wire;

at least one second wire;

at least one detector, including;

at least one reference plate for defining at least one space, and all of the reference plates being electrically coupled to the first wire;

at least one detecting plate, each of which residing in one of the at least one space and being electrically coupled to one of the at least one second wire, wherein the dimension of each detecting plate is equal or approximately equal the total dimension of all of the reference plates; and

a controller for providing an electrical signal to the first wire and each second wire, and detecting a touch or approach by an external object with respect to each detecting plate based on a corresponding signal difference between each second wire and the first wire, respectively, wherein if the signal difference between one of the second wires and the first wire is positive, then the signal of the second wire is one of a first type and a second type, and if the signal difference between one of the second wires and the first wire is negative, then the signal of the second wire is the other of the first and second types.

2. The capacitive sensor of claim 1, wherein the at least one reference plate defines a space in which the detecting plate resides, and the at least one reference plate defines an opening through which a corresponding second wire is electrically coupled to the detecting plate.

3. The capacitive sensor of claim 2, wherein the space is defined by a single reference plate.

4. The capacitive sensor of claim 1, wherein each detector includes at least two reference plates, and the at least two reference plates and a portion of the first wire surround the detecting plate and define an opening through which a corresponding second wire is electrically coupled to the detecting plate.

5. The capacitive sensor of claim 1, wherein the corresponding signal difference of each detector touched or approached by the external object is greater or less than a threshold, wherein the corresponding signal difference of each detector is the signal difference between a corresponding second wire and the first wire.

6. The capacitive sensor of claim 1, wherein when the corresponding signal difference of each detector touched or approached by the external object is positive, the corresponding signal difference of each detector not touched or approached by the external object is negative, wherein the corresponding signal difference of each detector is the signal difference between a corresponding second wire and the first wire.

7. The capacitive sensor of claim 1, wherein when the corresponding signal difference of each detector touched or approached by the external object is negative, the corresponding signal difference of each detector not touched or approached by the external object is positive, wherein the corresponding signal difference of each detector is the signal difference between a corresponding second wire and the first wire.

8. The capacitive sensor of claim 1, wherein a corresponding signal difference of each detector before and after a touch or approach is a first signal difference and a second signal difference, respectively, and the difference between and first and second signal differences is greater or less than a threshold.

9. The capacitive sensor of claim 1, further comprising a shielding line, which surrounds the at least one detector, the first wire and each second wire.

10. The method of claim 1, wherein the area of a side of each detecting plate facing towards a touch-sensitive sensor is smaller than that of opposite side, wherein the area of the side facing the touch-sensitive sensor and the area of the opposite side can be areas in a range with the same width between the two sides.

11. A capacitive sensor using signal differences for detection, comprising:

a first wire;

at least one second wire;

at least one reference plate for defining at least one space, and all of the reference plates being electrically coupled to the first wire;

at least one detecting plate, each of which residing in one of the at least one space and being electrically coupled to one of the at least one second wire, wherein the dimension of each detecting plate is equal or approximately equal the total dimension of all of the reference plates; and

a controller for performing at least the following operations;

providing an electrical signal to the first wire and each second wire continuously at a plurality of periods to obtain a reference value of the first wire and a detection value of each second wire;

taking one of the periods as an initial period, while other periods as detecting periods;

in the initial period, recording the difference between each detection value and the reference value an initial difference;

in each detecting period, generating each detection value and the reference value as a detection difference for each detection value; and

in each detecting period, identifying a detection value as one of first and second types if its detection difference is greater or less than the initial difference by a threshold, and a detection value is identified as the other of the first or second types if its detection difference is not greater or less than the initial difference by the threshold.

12. The capacitive sensor using signal differences for detection of claim 11, wherein when the detection difference of each detection value identified as the first type is greater than the initial difference, the detection difference of each detection value identified as the second type is less than the initial difference.

13. The capacitive sensor using signal differences for detection of claim 11, wherein when the detection difference of each detection value identified as the first type is less than the initial difference, the detection difference of each detection value identified as the second type is greater than the initial difference.

14. The capacitive sensor using signal differences for detection of claim 11, wherein the reference value is generated based on the signal of at least one reference plate, the at least one reference plate defines a plurality of spaces, and each detection value is generated based on the signal of one of the plurality of detecting plates, each detecting plate resides in one of these spaces.

15. The capacitive sensor using signal differences for detection of claim 11, wherein the area of a side of each detecting plate facing towards a touch-sensitive sensor is smaller than that of opposite side, wherein the area of the side facing the touch-sensitive sensor and the area of the opposite side can be areas in a range with the same width between the two sides.

16. A detection method of a capacitive sensor using signal differences, comprising:

providing a first wire and at least one second wire;

providing at least one reference plate for defining at least one space, and all of the reference plates being electrically coupled to the first wire;

providing at least one detecting plate, each of which residing in one of the at least one space and being electrically coupled to one of the at least one second wire, wherein the dimension of each detecting plate is equal or approximately equal the total dimension of all of the reference plates;

providing an electrical signal to the first wire and each second wire continuously at a plurality of periods to obtain a reference value of the first wire and a detection value of each second wire;

taking one of the periods as an initial period, while other periods as detecting periods;

in the initial period, recording the difference between each detection value and the reference value an initial difference;

in each detecting period, generating each detection value and the reference value as a detection difference for each detection value; and

in each detecting period, identifying a detection value as one of first and second types if its detection difference is greater or less than the initial difference by a threshold, and a detection value is identified as the other of the first or second types if its detection difference is not greater or less than the initial difference by the threshold.

17. The detection method of a capacitive sensor using signal differences of claim 16, wherein when the detection difference of each detection value identified as the first type is greater than the initial difference, the detection difference of each detection value identified as the second type is less than the initial difference.

18. The detection method of a capacitive sensor using signal differences of claim 16, wherein when the detection difference of each detection value identified as the first type is less than the initial difference, the detection difference of each detection value identified as the second type is greater than the initial difference.

19. The detection method of a capacitive sensor using signal differences of claim 16, wherein the reference value is generated based on the signal of at least one reference plate, the at least one reference plate defines a plurality of spaces, and each detection value is generated based on the signal of one of a plurality of detecting plates, each detecting plate resides in one of these spaces.

20. The detection method of a capacitive sensor using signal differences of claim 19, wherein the area of a side of each detecting plate facing towards a touch-sensitive sensor is smaller than that of opposite side, wherein the area of the side facing the touch-sensitive sensor and the area of the opposite side can be areas in a range with the same width between the two sides.