Hover sensor

• US 10,120,512 B2
• Filed: 04/08/2016
• Issued: 11/06/2018
• Est. Priority Date: 04/08/2016
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Tang, Yingying, Qiao, Tianzhu
• Primary Examiner(s): Khoo, Stacy
• Application Number:
  US15/094,794
• Publication Number:
  US 20170293376A1
• Time in Patent Office: 942 Days
• CPC Class Codes: G06F 2203/04101 2.5D-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 and also measures the distance of the input means within a short range in the Z direction, possibly with a separate measurement setup
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes

Abstract

Examples are disclosed herein that relate to hover sensing. One example provides a hover sensor comprising an electrode array including a first electrode subset and a second electrode subset, each electrode in the first electrode subset coupled to a corresponding electrode in the second electrode subset at a respective node and separated from the corresponding electrode by a gap, a charge circuit configured to charge the first electrode subset substantially oppositely about a reference voltage to the second electrode subset, an integration circuit configured to, for each respective node, store a net charge on a capacitor and provide an output voltage based on the net charge stored on the capacitor, and a controller. The controller is configured to indicate a presence of a hover object responsive to identifying at least a threshold voltage change based on a sample of the output voltage.

Claims

1. A hover sensor, comprising:

an electrode array including a first electrode subset and a second electrode subset, each electrode in the first electrode subset coupled to a corresponding electrode in the second electrode subset at a respective node and separated from the corresponding electrode by a gap substantially corresponding to at least a human hand size range, each electrode in the electrode array being used to store a corresponding charge via a self-capacitance of that electrode and to receive the corresponding charge;

a charge circuit configured to charge the first electrode subset substantially oppositely about a reference voltage to the second electrode subset;

an integration circuit configured to, for each respective node, store a net charge on a capacitor and provide an output voltage based on the net charge stored on the capacitor; and

a controller configured to indicate a presence of a hover object responsive to identifying at least a threshold voltage change based on a sample of the output voltage.

2. The hover sensor of claim 1, wherein the first electrode subset and the second electrode subset each include two electrodes such that each electrode in the first electrode subset is separated from the corresponding electrode in the second electrode subset by another electrode in one of the first and second electrode subsets.

3. The hover sensor of claim 1, wherein the first electrode subset and the second electrode subset each include a plurality of electrodes, each electrode in the first electrode subset separated from the corresponding electrode in the second electrode subset by another electrode in the first electrode subset and another electrode in the second electrode subset.

4. The hover sensor of claim 1, wherein the first electrode subset and the second electrode subset each include four electrodes such that each electrode in the first electrode subset is separated from the corresponding electrode in the second electrode subset by three other electrodes.

5. The hover sensor of claim 1, further comprising, for each respective node, transfer switches operable to couple corresponding electrodes to that respective node.

6. The hover sensor of claim 1, wherein the integration circuit is configured to, for each respective node, receive a net charge for each of a number of integration periods and to store on the capacitor a cumulative charge that is a sum of the net charges received for each of the number of integration periods.

7. The hover sensor of claim 6, further comprising a sample switch operable to couple the output voltage of the integration circuit to an input of an analog-to-digital converter.

8. The hover sensor of claim 7, wherein the analog-to-digital converter is configured to digitally sample the output voltage and provide the sample of the output voltage to the controller.

9. The hover sensor of claim 6, further comprising a reset switch operable to discharge the capacitor.

10. The hover sensor of claim 6, wherein the capacitor has a capacitance, the hover sensor further comprising a feedback circuit configured to select the number of integration periods and the capacitance to increase a dynamic range of the integration circuit.

11. The hover sensor of claim 1, further comprising, for each respective node, one or more switchable capacitors.

12. The hover sensor of claim 11, wherein, for each respective node, the one or more switchable capacitors are arranged upstream of that respective node.

13. The hover sensor of claim 11, wherein the controller is configured to determine whether to switch each of the one or more switchable capacitors to maximize cancellation of parasitic charge between electrodes coupled to that respective node.

14. A method of hover sensing, comprising:

charging a first electrode subset of an electrode array substantially oppositely about a reference voltage to a second electrode subset of the electrode array, each electrode in the first electrode subset coupled to a corresponding electrode in the second electrode subset at a respective node and separated from the corresponding electrode by a gap substantially corresponding to at least a human hand size range;

receiving, at each respective node, a net charge that is a sum of charges received from a corresponding pair of electrodes, the charges being stored on the corresponding pair of electrodes via a respective self-capacitance of each of the corresponding pair of electrodes;

storing, for each respective node, the net charge on a capacitor;

providing, for each respective node, an output voltage based on the net charge stored on the capacitor; and

indicating a presence of a hover object responsive to identifying at least a threshold voltage change based on a sample of the output voltage.

15. The method of claim 14, wherein storing the net charge on the capacitor includes receiving a net charge for each of a number of integration periods and storing on the capacitor a cumulative charge that is a sum of the net charges received for each of the number of integration periods.

16. The method of claim 15, further comprising coupling the output voltage based on the cumulative charge to an input of an analog-to-digital converter.

17. The method of claim 16, further comprising digitally sampling the output voltage at the analog-to-digital converter to derive the sample of the output voltage.

18. A hover sensor, comprising:

an electrode array including a first electrode subset and a second electrode subset, each electrode in the first electrode subset coupled to a corresponding electrode in the second electrode subset at a respective node;

a charge circuit configured to charge the first electrode subset substantially oppositely about a reference voltage to the second electrode subset;

an integration circuit configured to, for each respective node, store a net charge on a capacitor and provide an output voltage based on the net charge stored on the capacitor;

a feedback circuit configured to select one or more operating parameters of the integration circuit to increase a dynamic range of the integration circuit; and

a controller configured to indicate a presence of a hover object responsive to identifying at least a threshold voltage change based on a sample of the output voltage.

19. The hover sensor of claim 18, wherein the one or more operating parameters include a capacitance of the capacitor.

20. The hover sensor of claim 18, wherein the one or more operating parameters include a number of integration cycles.