CAPACITIVE CONTROL PANEL

• US 20110057899A1
• Filed: 09/04/2009
• Published: 03/10/2011
• Est. Priority Date: 09/04/2009
• Status: Active Grant

• Current Assignee: Neodrón Limited (Atlantic IP Services Limited)
• Original Assignee: Atmel Corporation (Microchip Technology Incorporated)
• Inventors: Sleeman, Peter, Yilmaz, Esat, Brunet, Samuel
• Granted Patent: US 8,730,199 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G01L 1/146 for measuring force distributions, e.g. using force arrays G01L1/148 takes precedence
• CPC Class Codes: G06F 2203/04103 Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
• 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 3/0202 Constructional details or processes of manufacture of the input device
• 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: H03K 17/975 using a capacitive movable element
• CPC Class Codes: Y10T 29/4913 Assembling to base an electrical component, e.g., capacitor, etc.

Abstract

A control panel for proximity and force sensing, includes a cover layer, a first electrode layer including a first force sensor electrode, a second force sensor electrode positioned in a second electrode layer or on a support layer, and a dielectric substrate at least a portion of which is compressible and is positioned between the first and second force sensor electrodes. The support layer is positioned to support at the vicinity of the second force sensor electrode support location so that compression of the dielectric substrate and the separation of the first and second force sensor electrodes depends on the magnitude of a force applied to the cover layer. Touch sensor electrodes are positioned on one or more of the electrode layers such that their capacitance depends on proximity of an object such as a finger. Controllers measure the capacitance of the force and touch sensor electrodes respectively and output force and touch proximity signals.

Claims

1. A control panel having a touch sensor responsive to proximity of an object and a force sensor responsive to a force applied by an object, wherein the control panel comprises a sensing element comprising layers stacked in the order of:

a cover layer;

a first electrode layer comprising a first force sensor electrode;

a dielectric substrate layer, at least a portion of which is compressible;

a second electrode layer comprising a second force sensor electrode; and

a support layer for supporting the other layers at a support location in the vicinity of the second force sensor electrode, wherein at least one of the first and second electrode layer further comprises a first touch sensor electrode, and wherein the first and second force sensor electrodes and the compressible portion of the dielectric substrate layer are aligned with the support location so that a separation of the first and second force sensor electrodes depends on the magnitude of a force applied to the cover layer, and

wherein the control panel further comprises a controller comprising a first capacitive sense channel coupled to the second force sensor electrode for measuring a capacitance of the second force sensor electrode and outputting a corresponding force sensor output signal, and the controller further comprises a second capacitive sense channel coupled to the first touch sensor electrode for measuring a capacitance of the first touch sensor electrode and outputting a corresponding touch sensor output signal.

2. A control panel according to claim 1, wherein the controller further comprises a first drive channel arranged to apply a drive signal to the first force sensor electrode, and wherein the first sense channel is operable to measure a component of the drive signal applied to the first force sensor electrode which is coupled to the second force sensor electrode such that the capacitance of the second force sensor electrode measured by the first sense channel is the mutual-capacitance between the second force sensor electrode and the first force sensor electrode.

3. A control panel according to claim 1, wherein the first force sensor electrode is maintained at a system reference potential and the capacitance of the second force sensor electrode measured by the first sense channel is the self-capacitance of the second sensor force electrode to the system reference potential.

4. A control panel according to claim 1, wherein the first touch sensor electrode is comprised in the first electrode layer.

5. A control panel according to claim 4, wherein the second electrode layer further comprises a second touch sensor electrode, and the wherein the capacitive coupling measured by the second sense channel is the mutual-capacitance between the first touch sensor electrode and the second touch sensor electrode.

6. A control panel according to claim 5, wherein the controller further comprises a second drive channel arranged to apply a drive signal to the second touch sensor electrode, and wherein the second sense channel is operable to measure a component of the drive signal applied to the second touch sensor electrode which is coupled to the first touch sensor electrode to thereby measure the mutual-capacitance between the first touch sensor electrode and the second touch sensor electrode.

7. A control panel according to claim 1, wherein the capacitance of the first touch sensor electrode measured by the second sense channel is the self-capacitance of the first touch sensor electrode to a system reference potential.

8. A control panel according to claim 1, wherein the first and second force sensor electrodes and the compressible portion of the dielectric substrate layer are located towards an outer edge of the sensing element relative to the touch sensor electrode.

9. A control panel according to claim 1, wherein the first force sensor electrode has a greater areal extent than the second force sensor electrode.

10. A control panel according to claim 1, wherein whole of the dielectric substrate layer is compressible.

11. A control panel according to claim 10, wherein a thickness of the dielectric substrate layer at least one location between the force sensor electrodes and the touch sensor electrode is less than a thickness of the dielectric substrate layer elsewhere.

12. A control panel according to claim 1, wherein the support layer is provided by a lip in a housing in which the sensing element is mounted.

13. A control panel according to claim 1, wherein the cover layer, the first and second electrode layers and the dielectric substrate layer are formed from transparent material.

14. A control panel according to claim 1, wherein the first and second electrode layers comprise conductive material mounted directly to the dielectric substrate layer to define the respective electrodes.

15. A control panel according to claim 1, wherein the first and second electrode layers comprise respective first and second mounting sheets with conductive material mounted thereon to define the respective electrodes.

16. A control panel according to claim 15, wherein the first and/or second mounting sheet comprises Polyethylene terephthalate (PET).

17. A control panel according to claim 1, wherein the dielectric substrate layer comprises a layer of silicone.

18. A control panel according to claim 1, wherein the dielectric substrate layer comprises a layer of compressible adhesive.

19. A control panel according to claim 1, wherein the first touch sensor electrode is an element within a touch sensor electrode pattern that provides for a position sensitive touch sensor, and wherein the touch sensor output signal is based on the measured capacitance of the first touch sensor electrode and corresponding measured capacitances for other electrodes within the electrode pattern of the position sensitive touch sensor.

20. A method of sensing proximity of an object and a force applied by an object, the method comprising:

providing a sensing element comprising layers stacked in the order of;

a cover layer;

a first electrode layer comprising a first force sensor electrode, a dielectric substrate layer, at least a portion of which is compressible;

a second electrode layer comprising a second force sensor electrode;

wherein at least one of the first and second electrode layer further comprises a touch sensor electrode;

supporting the sensing element at a support location in the vicinity of the second force sensor electrode, wherein the first and second force sensor electrodes and the compressible portion of the dielectric substrate are aligned with the support location so that a separation of the first and second force sensor electrodes depends on the magnitude of a force applied to the cover layer;

measuring a capacitance of the second force sensor electrode and outputting a corresponding force sensor output signal; and

measuring a capacitance of the touch sensor electrode and outputting a corresponding touch sensor proximity output signal.

21. A control panel for proximity and force sensing, comprising:

a cover layer

a first electrode layer comprising a first force sensor electrode;

a second force sensor electrode;

a dielectric substrate at least a portion of which is compressible and is positioned between the first and second force sensor electrodes;

a support layer positioned to support the second force sensor electrode and the layers at the vicinity of the second force sensor electrode with a compressible portion of the dielectric substrate separating the first and second force sensor electrodes;

a touch sensor electrode positioned adjacent a layer and spaced from the force sensor electrodes and compressible portion of the dielectric substrate; and

a controller comprising a capacitive sense channel coupled to the second force sensor electrode capable of measuring capacitance thereof and outputting a corresponding force sensor signal, and a capacitive sense channel coupled to the touch sensor electrode capable of measuring capacitance thereof and outputting a corresponding touch sensor proximity signal.

22. A control panel according to claim 21 wherein the second force sensor electrode is on a second electrode layer positioned generally on the opposite side of the dielectric substrate from the first electrode layer.

23. A control panel according to claim 22 wherein the touch sensor electrode is on one of the first or second electrode layers.

24. A control panel according to claim 21 wherein the second force sensor electrode is positioned on or within the support layer.

25. A method, comprising;

providing a sensing element including cover layer, a first electrode layer comprising a first force sensor electrode, a second force sensor electrode, a dielectric substrate at least a portion of which is compressible and positioned between the first and second force sensor electrodes, and a touch sensor electrode;

supporting the sensing element at a location where the first and second force sensor electrodes and the compressible portion of the dielectric substrate are aligned with a support location so that a separation of the first and second force sensor electrodes depends on the magnitude of a force applied to the cover layer;

measuring a capacitance of the second force sensor electrode and outputting a corresponding force sensor output signal; and

measuring a capacitance of the touch sensor electrode and outputting a corresponding force sensor output signal.

26. A control panel, comprising:

a first electrode layer including a first force sensor electrode;

a second force sensor electrode;

a dielectric substrate at least a portion of which is compressible and is positioned between the first and second force sensor electrodes;

a support layer positioned to support the second force sensor electrode and the layers at the vicinity of the second force sensor electrode with a compressible portion of the dielectric substrate separating the first and second force sensor electrodes; and

a first touch sensor electrode laterally separated from the first and second force sensor electrodes.

27. The control panel of claim 26 wherein the dielectric compresses in response to force substantially only at the support layer supporting the second force sensor electrode.

28. The control panel of claim 26 wherein the first touch sensor electrode is disposed in the first electrode layer, and wherein the control panel further comprises a second touch sensor electrode separated from the first touch sensor electrode by a portion of the dielectric that does not compress when force is applied.