Methods and apparatus for capacitive sensing

• US 10,001,885 B2
• Filed: 05/12/2014
• Issued: 06/19/2018
• Est. Priority Date: 10/24/2008
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Pance, Aleksandar, Leung, Omar S., Amm, David T.
• Primary Examiner(s): Dharia, Prabodh M
• Application Number:
  US14/275,730
• Publication Number:
  US 20140247248A1
• Time in Patent Office: 1,499 Days
• Field of Search: 345156-184, 324660, 324681, 324686, 3616794, 361752, 3616793, 361681, 273237
• CPC Class Codes: G06F 1/1616 with folding flat displays, e.g. laptop computers or notebooks having a clamshell configuration, with body parts pivoting to an open position around an axis parallel to the plane they define in closed position
• CPC Class Codes: G06F 1/1643 the display being associated to a digitizer, e.g. laptops that can be used as penpads details related to the relative motion of the display enclosure with respect to the body enclosure, e.g. to move between laptop and tablet PC configuration G06F1/1615
• CPC Class Codes: G06F 1/169 the I/O peripheral being an integrated pointing device, e.g. trackball in the palm rest area, mini-joystick integrated between keyboard keys, touch pads or touch stripes G06F1/1643 takes precedence; constructional details of pointing devices G06F3/033
• 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 2203/04108 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 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: H03K 17/955 using a capacitive detector
• 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 17/975 using a capacitive movable element
• CPC Class Codes: H03K 17/98 having a plurality of control members, e.g. keyboard
• CPC Class Codes: H03K 2217/96077 comprising an electrode which is floating

Abstract

The present disclosure addresses methods and apparatus facilitating capacitive sensing using a conductive surface, and facilitating the sensing of proximity to the conductive surface. The sensed proximity will often be that of a user, but can be another source of a reference voltage potential. In some examples, the described systems are capable of sensing capacitance (including parasitic capacitance) in a circuit that includes the outer conductive surface, and where that outer conductive surface is at a floating electrical potential. In some systems, the systems can be switched between two operating modes, a first mode in which the system will sense proximity to the conductive surface, and a second mode in which the system will use a capacitance measurement to sense contact with the conductive surface.

Claims

1. An electronic device comprising:

a plurality of capacitive sensor electrodes, wherein each capacitive sensor electrode in the plurality of capacitive sensor electrodes is disposed at a different location across a surface of the electronic device; and

first sensing circuitry, wherein the first sensing circuitry is configured to detect a contact location of a touch at the surface of the electronic device held at a first potential using the plurality of capacitive sensor electrodes, wherein the first sensing circuitry is configured to detect a capacitance indicative of a proximity between an external source of electric potential and the surface of the electronic device at a second floating potential using the plurality of capacitive sensor electrodes.

2. The electronic device defined in claim 1, wherein the sensing circuitry is further configured to detect an additional contact location at the surface of the electronic device associated with the touch.

3. The electronic device defined in claim 1, wherein the electronic device comprises a cellular telephone.

4. The electronic device defined in claim 1, further comprising:

an electronic device housing, wherein the surface of the electronic device forms a portion of the electronic device housing, and wherein at least one of the plurality of capacitive sensor electrodes forms a capacitance with the surface of the electronic device.

5. A proximity and touch sensing system operable in first and second modes, the proximity and touch sensing system comprising:

a plurality of capacitive sensor electrodes arranged across a surface of the proximity and touch sensing system, wherein the plurality of capacitive sensor electrodes are configured to generate capacitance signals; and

first sensing circuitry, wherein the first sensing circuitry is configured to identify a location of a touch at the surface held at a first potential using the capacitance signals when the proximity and touch sensing system is in the second mode, and wherein the first sensing circuitry is configured to detect a capacitance using the capacitance signals to determine whether an object is proximate to the surface at a second floating potential when the proximity and touch sensing system is in the first mode.

6. The proximity and touch sensing system defined in claim 5, wherein the proximity and touch sensing system is configured to switch from the first mode to the second mode when the sensing circuitry determines that the object is close to the surface.

7. The proximity and touch sensing system defined in claim 5, further comprising:

a light source, wherein the sensing circuitry is configured to illuminate the light source when the sensing circuitry determines that the object is close to the surface.

8. The proximity and touch sensing system defined in claim 5, wherein the object is a portion of a user of the proximity and touch sensing system.

9. The proximity and touch sensing system defined in claim 5, wherein the sensing circuitry is configured to determine whether contact between the object and the surface is likely and wherein the proximity and touch sensing system is configured to switch from the first mode to the second mode when the sensing circuitry determines that contact between the object and the surface is likely.

10. A method of operating an electronic device having first sensing circuitry and a plurality of capacitor electrodes disposed across a surface of the electronic device, the method comprising:

generating capacitance signals with the plurality of capacitor electrodes;

with the first sensing circuitry, determining a touch location at which an external source of electric potential is in contact with the surface of the electronic device held at a first potential; and

with the first sensing circuitry, detecting a capacitance indicative of a proximity between the external source of electric potential and the surface of the electronic device at a second floating potential using the capacitance signals.

11. The method defined in claim 10, further comprising:

with the sensing circuitry, determining whether the external source of electric potential is close to the surface; and

with the sensing circuitry, determining the touch location in response to determining that the external source of electric potential is close to the surface.

12. The method defined in claim 10, further comprising:

with the sensing circuitry, detecting a first capacitance indicative of a first proximity between the external source of electric potential and a first capacitor electrode in the plurality of capacitor electrodes and detecting a second capacitance indicative of a second proximity between the external source of electrical potential and a second capacitor electrode in the plurality of capacitor electrodes.

13. The method defined in claim 10, wherein detecting the capacitance comprises:

identifying a sensed capacitance in the capacitance signals.

14. The method defined in claim 13, further comprising:

determining whether the external source of electric potential is close to a given one of the plurality of capacitor electrodes.

15. The method defined in claim 14, further comprising:

illuminating a button in response to determining that the external source of electric potential is close to the given capacitor electrode.

16. The method defined in claim 14, wherein determining whether the external source of electric potential is close to the given capacitor electrode comprises:

identifying a rate of change of the sensed capacitance.

17. The method defined in claim 14, further comprising:

identifying a reference capacitance in the capacitance signals.

18. The method defined in claim 17, wherein determining whether the external source of electric potential is close to the given one of the plurality of capacitor electrodes comprises:

comparing the sensed capacitance to the reference capacitance.

19. The method defined in claim 14, further comprising:

determining the touch location at which the external source of electric potential is in contact with the surface of the electronic device in response to determining that the external source of electric potential is close to the given capacitor electrode.

20. The method defined in claim 10, further comprising:

with the sensing circuitry, determining an additional touch location at which the external source of electric potential is simultaneously in contact with the surface of the electronic device.