Method and apparatus for accurate coordinate calculation of objects in touch applications

• US 8,674,958 B1
• Filed: 06/12/2013
• Issued: 03/18/2014
• Est. Priority Date: 03/12/2013
• Status: Active Grant

• Current Assignee: Parade Technologies, Ltd.
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Kravets, Igor, Mandziy, Vasyl
• Primary Examiner(s): Sim, Yong H
• Application Number:
  US13/916,485
• Time in Patent Office: 279 Days
• Field of Search: 345/156, 345/173, 178 1801- 1806
• US Class Current: 345/173
• CPC Class Codes: G06F 3/04162 for exchanging data with external devices, e.g. smart pens, via the digitiser sensing hardware
• 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 3/0442 using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser
• 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

Systems and methods and techniques are disclosed for determining the position and size of an object touching a touch-sensitive display. One embodiment may comprise a set of reference templates—where each reference template is a model and/or data associated with a reference object of a given size. The reference templates may be determined on a priori basis—possibly created during a training phase for the touch display system. The training phase may be performed by stepping an object across a touch display and noting its actuation signal—while the modeling step may be performed by calculating actuation signals based on a model of objects of a given size. With an actual object, its position and size may be determined, calculated and/or estimated by solving a set of inverse finger response functions—e.g., as a set of over-determined linear equations.

Claims

1. A method for determining the position of an object on a touch sensitive display, the method comprising:

receiving a set of reference templates, each reference template comprising data associated with an actuation signal initiated by a reference object touching the touch sensitive display;

receiving a first actuation signal, the first actuation signal associated with a touch produced by a first object upon the touch sensitive display;

determining whether the first actuation signal meets a desired local maximum signal value;

if the first actuation signal meets a desired local maximum signal value, determining a set of boundary points substantially near the first actuation signal;

receiving sensor data from the set of boundary points; and

calculating a position of the first object; and

wherein calculating the position further comprises computing a set of inverse functions from the set of boundary points, the set of inverse functions comprising a set of inverse finger response functions.

2. The method of claim 1 wherein the method further comprises:

creating the set of reference templates from a priori information associated with the reference object touching the touch sensitive display.

3. The method of claim 2 wherein creating the set of reference templates from a priori information associated with the reference object further comprises:

performing a training phase, wherein the training phase comprises a set of data from a given reference object, the given reference object comprising an associated size; and

further wherein the training phase comprises receiving actuation data from the given reference object touching the touch-sensitive display at a set of coordinate points.

4. The method of claim 2 wherein creating the set of reference templates from a priori information associated with the reference object touching the touch sensitive display further comprises creating the set of reference templates from a set of modeling calculations, each modeling calculation comprises a function of size of reference object.

5. The method of claim 1 wherein determining whether the first actuation signal meets a desired local maximum value further comprises determining whether the actuation signal is above a noise threshold.

6. The method of claim 1 wherein determining the set of boundary points substantially near the first actuation signal further comprises determining a set of border cells substantially surrounding a set of center cells, the center cells sending actuation signals associated with the first object touching the touch display, wherein the touch display comprises a capacitive touch display.

7. The method of claim 6 wherein calculating the position of the first object further comprises:

receiving sensor data from the set of border cells; and

computing a set of inverse functions from the border cells, the set of inverse functions comprising a set of inverse finger response functions.

8. The method of claim 6 wherein calculating the position of the first object further comprises solving a set of over-determined system of linear equations.

9. The method of claim 8 wherein calculating the position of the first object further comprises calculating a size of the first object comprising solving a set of over-determined system of linear equations.

10. A touch display system, comprising:

a touch-sensitive display;

the touch-sensitive display comprising a set of sensor cells, each sensor cell capable of producing actuation signals when an object substantially touches the sensor cell;

a controller, the controller capable of receiving the actuation signals from the touch sensitive display; and

the controller further comprises a processor, the processor capable of executing computer readable instructions for determining a position of the object, the object producing an actuation signal upon a touch sensitive display, the method comprising;

receiving a set of reference templates, each reference template comprising data associated with an actuation signal initiated by a reference object touching the touch sensitive display;

receiving a first actuation signal, the first actuation signal associated with a touch produced by a first object upon the touch sensitive display;

determining whether the first actuation signal meets a desired local maximum signal value;

if the first actuation signal meets a desired local maximum signal value, determining a set of boundary points substantially near the first actuation signal;

receiving sensor data from the set of boundary cells; and

calculating a position of the first object; and

wherein calculating the position further comprises computing a set of inverse functions from the boundary point, the set of inverse functions comprising a set of inverse finger response functions.

11. The touch display system of claim 10 wherein the computer readable instructions further comprises:

creating a set of reference templates from a priori information associated with a reference object touching the touch sensitive display.

12. The touch display system of claim 11 wherein the computer readable instructions further comprises:

performing a training phase, wherein the training phase comprises a set of data from a given reference object, the given reference object comprising an associated size; and

further wherein the training phase comprises receiving actuation data from the given reference object touching the touch-sensitive display at a set of coordinate points.

13. The touch display system of claim 11 wherein the computer readable instructions further comprises:

creating a set of reference templates from a set of modeling calculations, each modeling calculation comprises a function of size of reference object.

14. The touch display system of claim 11 wherein the computer readable instructions further comprises:

determining a set of border cells substantially surrounding a set of center cells, the center cells sending actuation signals associated with the first object touching the touch display, wherein the touch display comprises a capacitive touch-sensitive display.

15. The touch display system of claim 14 wherein the computer readable instructions further comprises:

receiving sensor data from the set of border cells;

computing a set of inverse functions from the border cells, the set of inverse functions comprising a set of inverse finger response functions; and

calculating the position of the first object from the set of inverse functions.

20. The method of claim 11 wherein the method further comprises:

determining a set of border cells substantially surrounding a set of center cells, the center cells sending actuation signals associated with the first object touching the touch display;

receiving sensor data from the set of border cells;

computing a set of inverse functions from the border cells, the set of inverse functions comprising a set of inverse finger response functions; and

calculating the position of the first object from the set of inverse functions.

16. A method for determining the position of an object on a touch sensitive display, the method comprising:

receiving a set of reference templates, each reference template comprising data associated with an actuation signal initiated by a reference object touching the touch sensitive display and each reference object comprising a reference size;

receiving a first actuation signal, the first actuation signal associated with a touch produced by a first object at a position upon the touch sensitive display, the first object comprising a size;

determining whether the first actuation signal meets a desired local maximum signal value;

if the first actuation signal meets the desired local maximum signal value, determining a set of boundary points substantially near the first actuation signal;

receiving sensor data from the set of boundary points;

computing a set of inverse functions from the boundary points cells, the set of inverse functions comprising a set of inverse finger response functions; and

calculating the position of the first object from the set of inverse functions.

17. The method of claim 16 wherein the method further comprises:

creating a set of reference templates from a priori information associated with a reference object touching the touch sensitive display.

18. The method of claim 17 wherein the method further comprises:

performing a training phase, wherein the training phase comprises a set of data from a given reference object, the given reference object comprising an associated size; and

further wherein the training phase comprises receiving actuation data from the given reference object touching the touch-sensitive display at a set of coordinate points.

19. The method of claim 17 wherein the method further comprises:

creating a set of reference templates from a set of modeling calculations, each modeling calculation comprises a function of size of reference object.