Capacitance sensing matrix for keyboard architecture

• US 8,482,437 B1
• Filed: 11/15/2011
• Issued: 07/09/2013
• Est. Priority Date: 05/25/2006
• Status: Active Grant

• Current Assignee: Wistron Corporation
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Hua, Liu, XiaoPing, Jiang
• Primary Examiner(s): Ghayour, Mohammad
• Assistant Examiner(s): MURPHY, JEROLD B
• Application Number:
  US13/297,046
• Time in Patent Office: 602 Days
• Field of Search: 341/33, 345/173, 200/5.A, 200/600, 400/479.1
• US Class Current: 341/33
• 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 3/0202 Constructional details or processes of manufacture of the input device
• CPC Class Codes: G06F 3/0383 Signal control means within the pointing device
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• 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
• CPC Class Codes: G06F 3/04886 by partitioning the display area of the touch-screen or the surface of the digitising tablet into independently controllable areas, e.g. virtual keyboards or menus
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 2017/9602 characterised by the type or shape of the sensing electrodes
• CPC Class Codes: H03K 2217/960755 Constructional details of capacitive touch and proximity switches

Abstract

An apparatus and method for selecting a keyboard key based on a position of a presence of a conductive object on a sensing device and a pre-defined area of the keyboard key. The apparatus may include a sensing device and a processing device. The sensing device may include a plurality of sensor elements to detect a presence of a conductive object on the sensing device. Multiple keyboard keys are assigned to pre-defined areas of the sensing device. The processing device is coupled to the sensing device using capacitance sensing pins, and may be operable to determine a position of the presence of the conductive object, and to select a keyboard key based on the position of the conductive object and the pre-defined areas of the sensing device.

Claims

1. A method, comprising:

assigning a plurality of keys to correspond to pre-defined areas of a sensing surface of a mobile device having a plurality of sense elements coupled to a processing device, wherein the pre-defined areas are disposed adjacent to one another in a key matrix, wherein at least one of the plurality of sense elements corresponds to multiple ones of the pre-defined areas, and wherein a number of the plurality of keys is greater than a number of the plurality of sense elements;

determining a position of a conductive object proximate to the sensing surface by measuring capacitance on the plurality of sense elements; and

determining which key of the plurality of keys is selected based on the determined position of the conductive object with respect to the pre-defined areas of the key matrix.

2. The method of claim 1, wherein selecting the key comprises comparing the position of the conductive object with the pre-defined areas.

3. The method of claim 1, further comprising outputting data corresponding to the selected key from the processing device to a component external to the processing device.

4. The method of claim 1, wherein the plurality of sense elements are disposed in a plurality of rows of sense elements and a plurality of columns of sense elements, wherein each row and each column is coupled to the processing device, and wherein determining the position of the conductive object comprises:

measuring a capacitance of each row of sense elements of the capacitance sensor matrix of the mobile device;

determining a first dimension position based on the measured capacitance of the rows of sense elements;

measuring a capacitance of each column of sense elements of the capacitance sensor matrix; and

determining a second dimension position based on the measured capacitance of the columns of sense elements, wherein determining the position of the conductive object comprises determining the position of the conductive object using the first and second dimension positions.

5. The method of claim 1, wherein the pre-defined areas of the key matrix are arranged into a plurality of rows of the pre-defined areas, wherein the plurality of sense elements are arranged in a plurality of rows of sense elements, and wherein at least one of the plurality of rows of sense elements corresponds to at least one of the plurality of rows of the pre-defined areas.

6. A method comprising:

assigning a plurality of keys to correspond to pre-defined areas of a sensing surface of a mobile device having a plurality of sense elements coupled to a processing device, wherein the pre-defined areas are disposed adjacent to one another in a key matrix, wherein a sense element of the plurality of sense elements has at least three of the plurality of keys positioned to correspond at least a portion of the sense element;

determining a position of a conductive object proximate to the sensing surface by measuring capacitance on the plurality of sense elements;

determining which key of the plurality of keys is selected based on the determined position of the conductive object with respect to the pre-defined areas of the key matrix, and

outputting data corresponding to the selected key from the processing device to a component external to the processing device, wherein assigning the key matrix into pre-defined areas comprises defining a data structure comprising positional data of the pre-defined areas of the key matrix, wherein selecting the key comprises comparing the position of the conductive object with the positional data of the data structure to determine a pressed key of the key matrix, and wherein outputting the data comprises outputting data that corresponds to the pressed key.

7. A mobile device, comprising:

a plurality of sense elements to detect a conductive object proximate to a sensing surface of the mobile device, wherein a plurality of keys are assigned to correspond to pre-defined areas of the sensing surface, wherein the pre-defined areas are disposed adjacent to one another in a key matrix; and

a processing device coupled to the plurality of sense elements, wherein the processing device is configured to determine a position of the conductive object proximate to the sensing surface by measuring capacitance on the plurality of sense elements using one or more capacitance sensors, and to determine which key of the plurality of keys is selected based on the determined position of the conductive object with respect to the pre-defined areas of the key matrix, wherein at least one of the plurality of sense elements is used as at least part of a determination of three or more keys being selected.

8. The mobile device of claim 7, wherein the key matrix represents keys of a personal computer (PC) keyboard, and wherein the processing device is coupled to the plurality of sense elements using less than 21 pins.

9. The mobile device of claim 7, wherein the key matrix comprises approximately 48 keys, and wherein the processing device is coupled to the plurality of sense elements using 4 pins.

10. The mobile device of claim 7, wherein the key matrix comprises approximately 101 keys, and wherein the processing device is coupled to the plurality of sense elements using less than 12 pins.

11. The mobile device of claim 7, wherein the key matrix comprises approximately 107 keys, and wherein the processing device is coupled to the plurality of sense elements using less than 21 pins.

12. The mobile device of claim 7, wherein the key matrix comprises approximately 107 keys, and wherein the processing device is coupled to the plurality of sense elements using less than 12 pins.

13. The mobile device of claim 7, wherein the mobile device is at least one of a mobile phone, a personal data assistant (PDA), a laptop computer, a keyboard, a television, a remote control, a display, a handheld multi-media device, a handheld video player, a handheld gaming device, a control panel.

14. The mobile device of claim 7, wherein the plurality of sense elements configured in rows and columns to detect the conductive object, wherein each of the rows and columns is coupled to one of the one or more capacitance sensors.

15. The mobile device of claim 14, wherein the processing device comprises one or more capacitance sensors coupled to the rows and columns, wherein the one or more capacitance sensors are configured to measure a capacitance of each row of sense elements, and to measure a capacitance of each column of sense elements, and wherein the processing device is configured to determine the position of the key using the measured capacitance of the rows and columns.

16. The mobile device of claim 15, wherein at least one of the one or more capacitance sensors is a relaxation oscillator.

17. The mobile device of claim 7, further comprising an interface coupled to a component external to the processing device, wherein the processing device is configured to send key matrix data over the interface to the component that corresponds to the selected key.

18. An electronic device, comprising:

a plurality of sense elements; and

a processing device coupled to the key matrix, wherein the processing device comprising a capacitance sensor to determine a position of a conductive object proximate to a sensing surface of the electronic device, wherein the processing device is configured to;

assign a plurality of keys to correspond to pre-defined areas of the sensing surface, wherein the pre-defined areas are disposed adjacent to one another in a key matrix, wherein at least one of the plurality of sense elements is positioned to correspond to at least three of the pre-defined areas;

select a key of the key matrix when the position of the conductive object proximate to the sensing surface is determined to be within the pre-defined area corresponding to the key; and

detect a gesture performed by the conductive object on the sensing surface.

19. The electronic device of claim 18, wherein the pre-defined areas of the key matrix are arranged into multiple rows on the sensing surface, wherein the plurality of sense elements are arranged in a plurality of rows of sense elements, and wherein at least one of the plurality of rows of sense elements corresponds to a plurality of rows of the pre-defined areas.