TOUCH AND HOVER SIGNAL DRIFT COMPENSATION

• US 20120050210A1
• Filed: 09/30/2010
• Published: 03/01/2012
• Est. Priority Date: 08/27/2010
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: King, Brian Michael, Leung, Omar, Bernstein, Jeffrey Traer, Mucignat, Andrea, Cieplinski, Avi E., Subramani, Praveen R., Piche, Marc J., Amm, David T., Kerr, Duncan Robert, Puskarich, Paul G., Choudry, Muhammad U.
• Granted Patent: US 8,614,693 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• 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 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 2203/04108 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 2203/04111 Cross over in capacitive digitiser, i.e. details of structures for connecting electrodes of the sensing pattern where the connections cross each other, e.g. bridge structures comprising an insulating layer, or vias through substrate
• 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 3/041662 using alternate mutual and self-capacitive scanning
• 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

Compensation for signal drift in a touch and hover sensing device is disclosed. A touch and hover sensing device can include a sensing panel to sense an object touching or hovering over the panel, a grounding device to periodically interact with the panel, and a control system to measure capacitance of the panel when the grounding device interacts with the panel, where the measurement captures any signal drift in the panel, and to set the measurement as a new baseline capacitance of the panel. Alternatively, the touch and hover sensing device can forgo the grounding device and configure the control system to measure capacitance of the panel either when there has been no touching or hovering object or when there is a substantially stationary touching or hovering object at the panel for a determinative time period, where the measurement captures any signal drift in the panel, and to set the measurement from this time period as the new baseline capacitance. The control system can apply the new baseline capacitance to touch and hover measurements so as to compensate for the signal drift.

Claims

1. A touch and hover sensing device comprising:

a sensing panel configured to sense an object touching or hovering over the panel;

a grounding device configured to periodically interact with the sensing panel; and

a touch and hover control system configured to measure capacitance of the panel when the grounding device interacts with the panel and to set the measurement as a baseline capacitance of the device.

2. The device of claim 1, wherein the grounding device is a cover plate, and wherein the control system is configured to measure the capacitance of the panel when the cover plate covers the panel.

3. The device of claim 1, wherein the grounding device is a docking station, and wherein the control system is configure to measure the capacitance of the panel when the panel is docked in the docking station.

4. The device of claim 1, wherein the control system is configured to set the measurement as the baseline capacitance so as to compensate for signal drift in the panel.

5. The device of claim 1, wherein the control system is configured to suspend setting the measurement to the baseline capacitance when the grounding device does not interact with the panel.

6. A touch and hover sensing device comprising:

a sensing panel configured to sense an object touching or hovering over the panel; and

a touch and hover control system configured to determine a device status and, according to the determined status, to measure capacitance of the panel and set the measurement as a baseline capacitance of the device.

7. The device of claim 6, wherein the device status is that the device is idle for a specific period, and wherein the control system is configured to set the measurement as the baseline capacitance when the device is idle for the specific period.

8. The device of claim 6, wherein the device status is that the device is detecting a substantially stationary touching or hovering object at the panel for a specific period, and wherein the control system is configured to set the measurement as the baseline capacitance when the device is detecting the substantially stationary touching or hovering object at the panel for the specific period.

9. The device of claim 6, wherein the control system is configured to set the measurement as the baseline capacitance so as to compensate for signal drift in the panel.

10. The device of claim 6, wherein the control system is configured to measure the capacitance over a specific period and set an average of the measurements over the specific period as the baseline capacitance.

11. A method of compensating for signal drift in a sensing panel, the method comprising:

measuring capacitance at the panel indicative of an object proximate to the panel;

determining whether the object is substantially stationary at the panel for a predetermined time period; and

based on the determination, setting at least one capacitance measurement from the predetermined time period as a baseline capacitance for the panel.

12. The method of claim 11, further comprising deferring setting the baseline capacitance if at least one of the panel is not substantially stationary, the object is not substantially stationary, the predetermined time period has not expired, or the capacitance measurements are erroneous.

13. The method of claim 11, further comprising applying the baseline capacitance to subsequent measurements to compensate for the signal drift.

14. The method of claim 11, wherein setting at least one capacitance measurement comprises, if the object is substantially stationary, setting an average of the capacitance measurements over the predetermined time period as the baseline capacitance.

15. The method of claim 11, wherein setting at least one capacitance measurement comprises, if the object is not substantially stationary, suspending the setting of the at least one capacitance measurement as the baseline capacitance.

16. A method of compensating for signal drift in a sensing panel, the method comprising:

measuring capacitance at the panel indicative of lack of an object proximate to the panel for a determinative time period; and

setting the capacitance measurement as a baseline capacitance of the panel.

17. The method of claim 16, further comprising deferring setting the baseline capacitance if at least one of the panel is not substantially stationary or the capacitance measurement is erroneous.

18. The method of claim 16, further comprising detecting a grounding device configured to interact with the panel, the interaction indicative of the lack of a proximate object for the determinative time period.

19. The method of claim 16, wherein setting the capacitance measurement comprises setting the measurement when there has been the lack of a proximate object for the determinative time period.

20. The method of claim 16, further comprising adjusting a subsequent capacitance measurement based on the baseline capacitance to compensate for the signal drift.

21. The method of claim 16, wherein the signal drift is indicative of an environmental change, an operating change, or a mechanical change of the device.

22. A touch and hover sensing device comprising:

a touch and hover sensing panel having multiple sensors configured to detect one or more objects proximate to the panel, wherein the objects touch the panel to cause a touch event, hover over the panel to cause a hover event, or touch and hover concurrently to cause touch and hover events; and

a touch and hover control system configured to measure capacitance of the panel during predetermined compensation periods and to set a baseline capacitance of the panel based on the capacitance measurement so as to compensate for signal drift in the panel.

23. The device of claim 22, wherein the predetermined compensation periods comprise at least one of a period during which a grounding device interacts with the panel, a period during which there are no touch or hover events at the panel, or a period during which an object touching or hovering over the panel is substantially stationary.

24. The device of claim 22, further comprising a display configured to display graphical information to select in response to the touch and hover events.

25. The device of claim 22 incorporated into at least one of a mobile phone, a digital media player, or a computer.