DYNAMICALLY RECONFIGURABLE CAPACITIVE SENSOR ARRAY

• US 20150280707A1
• Filed: 03/31/2014
• Published: 10/01/2015
• Est. Priority Date: 03/31/2014
• Status: Active Grant

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Hovden, Torbjorn
• Granted Patent: US 9,444,454 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• 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 2203/04108 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 3/0202 Constructional details or processes of manufacture of the input device
• CPC Class Codes: G06F 3/023 Arrangements for converting discrete items of information into a coded form, e.g. arrangements for interpreting keyboard generated codes as alphanumeric codes, operand codes or instruction codes
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells
• CPC Class Codes: H03K 17/955 using a capacitive detector
• CPC Class Codes: H03K 17/9622 using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 17/98 having a plurality of control members, e.g. keyboard
• CPC Class Codes: H03K 2217/96027 Piezoelectric snap spring

Abstract

In a keyboard of the type including a key cap and a capacitive sensor disposed underneath the key cap, a method including operating the capacitive sensor in a first mode configured for near field detection and generating a first variable capacitance, and operating the capacitive sensor in a second mode configured for far field detection and generating a second variable capacitance. The method further includes determining key motion based on the first variable capacitance and determining finger presence based on the second variable capacitance.

Claims

5-1. The keyboard of claim 1, wherein each of the subset of key assemblies further comprises a planar translation effecting (PTE) mating feature including a ramp configured such that the key cap translates vertically and laterally in a planar manner relative to the PTE feature in response to the input object contact.

10. The keyboard of claim 10, wherein:

the processing system further comprises an external switch and a microcontroller configured to selectively connect the three electrodes, respectively, to the transmitter circuitry and receiver circuitry through the external switch.

13. The keyboard of claim 13, wherein the compressible dielectric and the capacitive sensor exhibit an area of contact which increases during a down stroke of the key cap, thereby changing at least the first variable capacitance when in the first mode.

14. The keyboard assembly of claim 14, wherein the area of contact increases substantially monotonically with downward key cap motion.

16. A processing system for a keyboard input device of the type including a plurality of key assemblies each having a key cap and a capacitive sensor disposed underneath the key cap, the processing system configured to be communicatively coupled to each of the capacitive sensors and configured to selectively operate each capacitive sensor in a first mode and a second mode;

wherein the first mode operates the capacitive sensor in a fine pitch configuration and determines a first variable capacitance, and the second mode operates the capacitive sensor in a coarse pitch configuration and determines a second variable capacitance; and

wherein key cap motion is determined based on the first variable capacitance and finger presence is determined based on the second variable capacitance.

17. The processing system of claim 16, further configured to operate in the second mode until a finger is detected, and to time multiplex between the first and second modes in response to the detection of a finger.

18. The processing system of claim 16, wherein the capacitive sensor comprises a plurality of parallel conductors separated by a distance in the range of about 50 to about 150 micrometers, and further wherein the processing system is configured to switch between the first and second modes at a frequency in the range of about 50 to 100 Hz.

19. In a keyboard of the type including a key cap and a capacitive sensor disposed underneath the key cap, a method comprising:

operating the capacitive sensor in a first mode configured for near field detection and generating a first variable capacitance;

operating the capacitive sensor in a second mode configured for far field detection and generating a second variable capacitance;

determining key motion based on the first variable capacitance; and

determining finger presence based on the second variable capacitance.

20. The method of claim 19, wherein:

operating the capacitive sensor in the first mode comprises configuring the capacitive sensor in a fine pitch arrangement of parallel conductors; and

operating the capacitive sensor in the second mode comprises configuring the parallel conductors in a coarse pitch arrangement including a first subset of adjacent transmitter electrodes and a second subset of adjacent receiver electrodes.