METHOD AND DEVICE FOR TOUCH SCREEN SENSING, CORRESPONDING APPARATUS AND COMPUTER PROGRAM PRODUCT

• US 20160259448A1
• Filed: 12/17/2015
• Published: 09/08/2016
• Est. Priority Date: 03/06/2015
• Status: Active Grant

• Current Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SRL (STMicroelectronics NV)
• Inventors: GUARNERI, Nunziata Ivana
• Granted Patent: US 11,023,075 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 3/03545 Pens or stylus
• 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 3/04186 Touch location disambiguation
• CPC Class Codes: G06F 3/044 by capacitive means
• 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

A capacitive touch screen of e.g., a mobile communications device such as a smart phone or tablet is operated by producing a capacitance map of capacitance values for the screen, wherein the capacitance values are indicative of locations of the screen exposed to touch by a user, and by identifying locations of the screen exposed to touch by a user by comparing the capacitance values against settings of sensing thresholds. Descriptor processing is applied to the capacitance map to extract a set of descriptors indicative of said screen being in one of a plurality of different operating conditions. A set of rules is applied to these descriptors to identify one of a plurality of different operating conditions, and selecting the setting of sensing thresholds as a function of the operating condition thus identified.

Claims

1. A method, comprising:

operating a capacitive touch screen the operating including;

producing a capacitance map of capacitance values for said screen; and

identifying locations of the screen exposed to touch by a user by comparing said capacitance values against at least one sensing threshold;

extracting a plurality of descriptors by processing the capacitance map descriptor processing, the descriptors being indicative of said screen being in one of a plurality of different operating conditions;

identifying at least one of the plurality of different operating conductions by applying to said descriptors classifier rules; and

selecting said at least one sensing threshold as a function of the at least one operating condition identified.

2. The method of claim 1 wherein said capacitance map is a mutual capacitance map of said touch screen.

3. The method of claim 1, further comprising extracting said descriptors as global descriptors computed over a whole of said capacitance map.

4. The method of claim 1 wherein said processing includes:

checking said capacitance values against a set of possible ranges for said capacitance values; and

extracting said descriptors as a function of said checking.

5. The method of claim 4 wherein said extracting includes selecting from one of:

maximum of positive values for said capacitance values;

maximum of the negative values for said capacitance values;

sum of all negative values for said capacitance values;

sum of all positive values for said capacitance values;

sum of the positive values for said capacitance values in a first positive range;

sum of the positive values for said capacitance values in a second positive range;

sum of the positive values for said capacitance values in a third positive range;

sum of the negative values for said capacitance values in a first negative range;

sum of the negative values for said capacitance values in a second negative range;

sum of the negative values for said capacitance values in a third negative range.

6. The method of claim 1, further comprising producing said capacitance map as a map of capacitance strength values based on the following:

Strength=Baseline−

RawData

where;

Baseline is the capacitance value at a location of said screen when untouched, and

RawData is a capacitance variation due to a conductor element at said location of said screen.

7. The method of claim 1 wherein said plurality of different operating conditions includes operating conditions selected from:

user'"'"'s fingers dry and screen held by user;

stylus dry and screen held by user;

stylus dry and screen resting on insulating surface;

user'"'"'s fingers dry and screen resting on insulating surface;

user'"'"'s fingers wet and screen held by user;

user'"'"'s fingers wet and screen resting on insulating surface; and

untouched water on screen.

8. The method of claim 1 wherein:

said plurality of different operating conditions includes, at least for one and preferably for both of said screen held by user and said screen resting on insulating surface, dry operating conditions for user'"'"'s fingers and for a stylus, and

the method includes discriminating between finger operation and stylus operation in said dry operating conditions.

9. A device, comprising:

a capacitive touch screen;

electronic circuitry coupled to the screen, the circuitry configured to;

produce a capacitance map of capacitance values for said screen;

extract descriptors from said capacitance map, the descriptors being indicative of said screen being in one of a plurality of different operating conditions;

apply to said descriptors a set of classifier rules to identify said one of a plurality of different operating conditions; and

compare said capacitance values against at least one sensing threshold selected as a function of the operating condition identified,

identify locations of the screen exposed to touch by a user based on the comparison.

10. The device of claim 9 wherein the plurality of different operating conditions includes operating conditions selected from:

user'"'"'s fingers dry and screen held by user;

stylus dry and screen held by user;

stylus dry and screen resting on insulating surface;

user'"'"'s fingers dry and screen resting on insulating surface;

user'"'"'s fingers wet and screen held by user;

user'"'"'s fingers wet and screen resting on insulating surface; and

untouched water on screen