Human-machine interface with transparent capacitive sensing surface

Abstract

A human-machine interface (HMI) for contactless entry of commands by gestures is proposed. The HMI comprises a transparent panel with a transparent sensing surface, a detection chipset connected to the electrodes of the sensing surface for determining first, second, third and fourth capacitance observables, and a processor. The processor is configured to compute a time series of position coordinates depending on the capacitance observables and is further configured to map the time series of position coordinates onto one or more commands and to output these commands.

Description

HUMAN-MACHINE INTERFACE WITH TRANSPARENT CAPACITIVE SENSING SURFACEBackground of the Invention

[0001] The invention generally relates to human-machine interfaces (HMIs), in particular an HMI with a transparent sensing surface that allows a user to input commands contactlessly by gestures.Summary of the Invention

[0002] According to a first aspect of the invention, an HMI comprises: a transparent panel comprising a sensing surface, the capacitive sensing surface comprising a first sector with a first electrode, a second sector with a second electrode, a third sector with a third electrode and a fourth sector with a fourth electrode, the sensing surface, in particular, the first, second, third and fourth electrodes, being transparent; a detection chipset connected to the first electrode for determining a first capacitance observable, to the second electrode for determining a second capacitance observable, to the third electrode for determining a third capacitance observable and to the fourth electrode for determining a fourth capacitance observable; a processor connected to the detection chipset and configured to compute a time series of position coordinates, the position coordinates including first and second position coordinates, which, at an instant of time are computed as:X = (CX1 -CX2) / (C1 +C2+C3+C4), andY = ((CY1 -CY2) / (C1 +C2+C3+C4), where X is the first position coordinate, Y is the second position coordinate, C1 is the first capacitance observable, C2 is the second capacitance observable, C3 is the third capacitance observable, C4 is the fourth capacitance observable at the instant of time, CX1 is C1 +C4 or CX1 is C1 , CX2 is C2+C3 or, when CX1 is C1 , CX2 is C3, CY1 is C1 +C2 or, when CX1 is C1 , CY1 is 02, and CY2 is C3+C4 or, when CX1 is 01 , CY2 is 04. The processor is further configured to map the time series of position coordinates onto one or more commands and to output the one or more commands.

[0003] The first, second, third and fourth sectors may be arranged around a center of the sensing surface, the first sector being located opposite the third sector and the second sector being located opposite the fourth sector. The first, second, third and fourth sectors may be quadrants, i.e. , disk sectors with a central angle of 90°.

[0004] According to an embodiment, CX1 is C1 , CX2 is C3, CY1 is C2, and CY2 is C4. In this case, the centroid of the first electrode and the centroid of the third electrode lie on the X-axis (the axis of the X coordinates) while the centroid of the second electrode and the centroid of the fourth electrode lie on the Y-axis (the axis of the Y coordinates).

[0005] Alternatively, CX1 is C1 +C4, CX2 is C2+C3, CY1 is C1 +C2, and CY2 is C3+C4. In this case, the centroid of both the first electrode and the fourth electrode and the centroid of both the second electrode and the third electrode lie on the X-axis while the centroid of both the first electrode and the second electrode and the centroid of both the third electrode and the fourth electrode lie on the Y-axis.

[0006] The position coordinates may include third position coordinates, which, at an instant of time are computed as Z = C1 +C2+C3+C4, where Z is the third position coordinate at the instant of time.

[0007] The sensing surface may comprise one or more counter-electrodes. The one or more counter-electrodes may be grounded or floating.

[0008] The processor may be configured to carry out the mapping of the time series of position coordinates onto one or more commands by pattern recognition.

[0009] The detection chipset may comprise one or more analog-to-digital converters with at least four sensing channels connected to the first, second, third and fourth electrodes, respectively.

[0010] The transparent panel may, e.g., comprise a glass or a plastic transparent panel (e.g., of a window, a door, a glass screen, etc.)

[0011] Additionally or alternatively, the transparent panel may comprise a display screen, e.g., of an LCD monitor, a LED monitor, an OLED screen, etc.

[0012] In the present document, the verb “to comprise” and the expression “to be comprised of’ are used as open transitional phrases meaning “to include” or “to consist at least of”. Unless otherwise implied by context, the use of singular word form isintended to encompass the plural, except when the cardinal number “one” is used: “one” herein means “exactly one”. Ordinal numbers (“first”, “second”, etc.) are used herein to differentiate between different instances of a generic object; no particular order, importance or hierarchy is intended to be implied by the use of these expressions. Furthermore, when plural instances of an object are referred to by ordinal numbers, this does not necessarily mean that no other instances of that object are present (unless this follows clearly from context). When this description refers to “an embodiment”, “one embodiment”, “embodiments”, etc., this means that the features of those embodiments can be used in the combination explicitly presented but also that the features can be combined across embodiments without departing from the invention, unless it follows from context that features cannot be combined.Brief Description of the Drawings

[0013] By way of example, preferred, non-limiting embodiments of the invention will now be described in detail with reference to the accompanying drawings, in which:

[0014] is a schematic illustration of an HMI in accordance with an aspect of the invention;

[0015] is an illustration of a first layout of a capacitive sensing surface;

[0016] is an illustration of a second layout of a capacitive sensing surface;

[0017] is an illustration of a third layout of a capacitive sensing surface;

[0018] is a general schematic diagram of the functional building blocks of an HMI according to an embodiment of the invention.Detailed Description of Preferred Embodiments

[0019] Fig. 1 schematically shows a human-machine interface (HMI) 10, comprising a glass screen 12 fitted into a frame 14. The HMI may serve a user to control operation of a device, e.g., a smart home hub, a lamp, air conditioning, a tablet / smartphone, a computer device as a HID (Human interface device), etc., with gestures, without touching the glass screen.

[0020] The HMI 10 comprises a capacitive transparent sensing surface 16 integrated into the glass screen 12, e.g., a layer of conductive transparent thin film material such as, e.g. ITO based, conductive ZnO based (AZO, GZO), silver of gold nanowires, or aconductive polymer tracks. The HMI further includes a controller 18, connected to the sensing surface 16. The controller is further connected (by wire or wirelessly) to one or more devices being controlled, illustrated for the sake of simplicity as a lamp 20 in Fig. 1. In the illustrated embodiment, the controller 18 is arranged in the frame of the glass screen 12.

[0021] The sensing surface 16 is subdivided into four quadrants, each having a respective sensing electrode therein. Figs. 2-4 illustrate different, non-limiting layouts of the sensing surface 16. Each sensing electrode may be surrounded by a respective counterelectrode. However, the counterelectrodes may be optional in certain configurations. The counterelectrodes may be grounded or floating.

[0022] As illustrated in Fig. 5, the controller 18 comprises a detection chipset 22 connected to the sensing electrodes 24A, 24B, 24C, 24D for determining corresponding capacitance observables C1 , C2, C3, C4, respectively, i.e., measured physical quantities indicative of the capacitance of the respective (sensing) electrode. The capacitance of each sensing electrode increases when a conductive or a dielectric object, e.g., a user’s hand 26, approaches it. When the object moves away from a sensing electrode, the respective capacitance decreases. The detection chipset 22 may comprise one or more capacitance-to-digital converters with at least four sensing channels connected to the first, second, third and fourth electrodes 24A, 24B, 24C, 24D, respectively.

[0023] The detection chipset 22 may include or be connected to a microprocessor or microcontroller 28 (e.g., an FPGA, an ASIC, a DSP or a CPU) that receives the capacitance observables C1 , C2, C3, C4 in digital format. The processor 28 computes position coordinates as:X = ((C1 +C4)-(C2+C3)) / (C1 +C2+C3+C4),Y = ((C1 +C2)-(C3+C4)) / (C1 +C2+C3+C4),Z = C1 +C2+C3+C4.

[0024] It shall be noted that the capacitance observables C1 , C2, C3, C4 may change over time and, accordingly, the computed position coordinates are time dependent. The time dependency has not been expressed explicitly in order not to overload the equations. X is the first position coordinate on an axis passing through the centroid of the first electrode and the fourth electrode (taken together) and through the centroid ofthe second electrode and the third electrode (taken together). Y is the second position coordinate on an axis passing through the centroid of the first electrode and the second electrode (taken together) and the centroid of the third electrode and the fourth electrode lie (taken together). The time series of X and Y coordinates indicate the trajectory of a moving object, e.g., the above-mentioned hand 26, over the sensing surface 16. The Z coordinate indicates a distance between the object and the sensing surface 16.

[0025] The time series of position coordinates X, Y and Z are then mapped onto one or more commands, which are provided as outputs. The mapping of the time series of position coordinates onto one or more commands may be achieved by pattern recognition 29, including classification of the observed trajectory into the most likely among several classes. These classes preferably correspond to the different commands that the HMI may output. The pattern recognition step 29 thus translates the observed trajectories into commands (this includes any signal that is understood as a command by the connected device, e.g., a predefined gesture). When the observed trajectory cannot be associated to a command with sufficient confidence level, the pattern recognition 29 may affect it to a class that does not correspond to a command for the actuator.

[0026] The HMI 10 may include a wireless communication module (not shown in the drawings), such as, e.g., a WiFi chipset, a Zigbee module, a Bluetooth module, etc. It should be noted, however, that the HMI may also be wired to the one or more devices that it controls.

[0027] It should be noted that position coordinates, in particular in the capacitive sensing surface configuration of Fig.4, could, alternatively be computed as:X = (C1 -C3) / (C1 +C2+C3+C4),Y = (C2-C4)) / (C1 +C2+C3+C4),Z = C1 +C2+C3+C4.

[0028] In this case, X is the first position coordinate on an axis passing through the centroid of the first electrode and though the centroid of the third electrode while Y is the second position coordinate on an axis passing through the centroid of the second electrode and through the centroid of the fourth electrode. The Z coordinate indicates a distance between the object and the sensing surface.

[0029] It shall be noted that the HMI according to the invention may be especially suited for large glass surfaces. Nevertheless, the invention may also be used on smaller glass surfaces, such as on display screens of mobile devices, such as e.g., portable computers, mobile phones (smart phones), tablets, etc.

[0030] It shall be noted that the HMI according to the invention may be also suited for large and small plastic transparent surfaces (e.g., made of or comprising PMMA).

[0031] While specific embodiments have been described herein in detail, those skilled in the art will appreciate that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention, which is to be given the full breadth of the appended claims and any and all equivalents thereof.

Claims

Claims:

1. A human-machine interface for contactless entry of commands by gestures, comprising a transparent panel comprising a sensing surface, the sensing surface comprising a first sector with a first electrode, a second sector with a second electrode, a third sector with a third electrode and a fourth sector with a fourth electrode, the first, second, third and fourth electrodes being transparent; a detection chipset connected to the first electrode for determining a first capacitance observable, to the second electrode for determining a second capacitance observable, to the third electrode for determining a third capacitance observable and to the fourth electrode for determining a fourth capacitance observable; a processor connected to the detection chipset and configured to compute a time series of position coordinates, the position coordinates including first and second position coordinates, which, at an instant of time are computed as:X = (CX1 -CX2) / (C1 +C2+C3+C4), andY = ((CY1 -CY2) / (C1 +C2+C3+C4), where X is the first position coordinate, Y is the second position coordinate, C1 is the first capacitance observable, C2 is the second capacitance observable, C3 is the third capacitance observable, C4 is the fourth capacitance observable at the instant of time, CX1 is C1 +C4 or CX1 is C1 , CX2 is C2+C3 or, when CX1 is C1 , CX2 is C3, CY1 is C1 +C2 or, when CX1 is C1 , CY1 is C2, and CY2 is C3+C4 or, when CX1 is C1 , CY2 is C4; the processor further configured to map the time series of position coordinates onto one or more commands and to output the one or more commands.

2. The human-machine interface as claimed in claim 1 , wherein the first, second, third and fourth sectors are arranged around a centre of the sensing surface, the first sector located opposite the third sector and the second sector located opposite the fourth sector.

3. The human-machine interface as claimed in claim 2, wherein the first, second, third and fourth sectors are quadrants.

4. The human-machine interface as claimed in any one of claims 1 to 3, wherein the position coordinates include third position coordinates, which, at an instant of timeare computed as Z = C1 +C2+C3+C4, where Z is the third position coordinate at the instant of time.

5. The human-machine interface as claimed in any one of claims 1 to 4, wherein the processor is configured to carry out the mapping of the time series of position coordinates onto one or more commands by pattern recognition.

6. The human-machine interface as claimed in any one of claims 1 to 5, wherein the detection chipset comprises one or more analog-to-digital converters with at least four sensing channels connected to the first, second, third and fourth electrodes.

7. The human-machine interface as claimed in any one of claims 1 to 6, wherein CX1 is C1 +C4, CX2 is C2+C3, CY1 is C1 +C2, and CY2 is C3+C4.

8. The human-machine interface as claimed in any one of claims 1 to 6, wherein CX1 is C1 , CX2 is C3, CY1 is C2, and CY2 is C4.

9. The human-machine interface as claimed in any one of claims 1 to 8, wherein the transparent panel comprises a glass panel.

10. The human-machine interface as claimed in any one of claims 1 to 9, wherein the transparent panel comprises a display screen.11 . The human-machine interface is as claimed in claims 2 to 7, taken in combination.

12. The human-machine interface is as claimed in claims 2 to 6 and 8, taken in combination.

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