Multipoint touchscreen

• US 8,125,463 B2
• Filed: 11/07/2008
• Issued: 02/28/2012
• Est. Priority Date: 05/06/2004
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Hotelling, Steven Porter, Strickon, Joshua, Huppi, Brian Q.
• Primary Examiner(s): Nguyen, Kimnhung
• Application Number:
  US12/267,540
• Publication Number:
  US 20090096758A1
• Time in Patent Office: 1,208 Days
• Field of Search: 345173-179, 178 1801- 1804
• US Class Current: 345/173
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• 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 2203/04104 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 2203/04105 Pressure sensors for measuring the pressure or force exerted on the touch surface without providing the touch position
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• CPC Class Codes: G06F 3/0414 using force sensing means to determine a position
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/04164 Connections between sensors and controllers, e.g. routing lines between electrodes and connection pads
• 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 3/044 by capacitive means
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• 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 touch panel having a transparent capacitive sensing medium configured to detect multiple touches or near touches that occur at the same time and at distinct locations in the plane of the touch panel and to produce distinct signals representative of the location of the touches on the plane of the touch panel for each of the multiple touches is disclosed.

Claims

1. A digital signal processing method, comprising:

receiving raw data, the raw data including values for each transparent capacitive sensing node of a touch screen;

filtering the raw data;

generating gradient data;

calculating the boundaries for touch regions base on the gradient data; and

calculating the coordinates for each touch region.

2. The method as recited in claim 1 wherein the boundaries are calculated using a watershed algorithm.

3. The digital signal processing method as recited in claim 1, wherein, prior to receiving the raw data, converging analog signals from each transparent capacity e sensing node of the touch screen into digitized signals corresponding to the analog signals, the digital signals constituting the raw data.

4. The digital signal processing method as recited in claim 1, wherein filtering the raw data comprises reducing noise in the raw data.

5. The digital signal processing method as recited in claim 1, wherein the raw for each transparent capacitive sensing node of a touch screen corresponds to a data point, and filtering the raw data removes single data points that are not connected to other data points.

6. The digital signal processing method as recited in claim 1, wherein filtering the raw data generates filtered raw data, and generating the gradient data is based on the filtered raw data.

7. The digital signal processing method as recited in claim 1, wherein the transparent capacitive sensing node of the touch screen produce a relatively low capacitive coupling value when a touch event occurs on the touch screen as compared to a no touch event, and wherein the gradient data corresponds to the capacitive coupling values.

8. The digital signal processing method as recited in claim 1, wherein calculating the coordinates of each touch region comprises calculating a centroid of each touch region with the raw data associated with each touch region.

9. The digital signal processing method as recited in claim 1,

wherein, prior to receiving the raw data, converging analog signals from each transparent capacity e sensing node of the touch screen into digitized signals corresponding to the analog signals, the digital signals constituting the raw data;

wherein the raw for each transparent capacitive sensing node of a touch screen corresponds to a data point, and filtering the raw data removes single data points that are not connected to other data points; and

wherein filtering the raw data generates filtered raw data, and generating the gradient data is based on the filtered raw data.

10. The digital signal processing method as recited in claim 9, wherein calculating the coordinates of each touch region comprises calculating a centroid of each touch region with the raw data associated with each touch region.

11. A computer system comprising:

a processor configured to execute instructions and to carry out operations associated with the computer system;

a display device that is operatively coupled to the processor;

a touch screen that is operatively coupled to the processor, the touch screen having transparent capacitive sensing nodes and providing analog data indicative of a touch event on the touch screen;

an analog to digital converter for receiving the analog data and providing digital raw data at an output thereof;

the processor operative in execution the instructions for;

receiving the digital raw data, the digital raw data including values for each transparent capacitive sensing node of a touch screen;

filtering the digital raw data to provide filtered raw data;

generating gradient data from the filtered raw data;

calculating the boundaries for touch regions base on the gradient data; and

calculating the coordinates for each touch region.

12. The computer system as recited in claim 11, wherein the processor calculates the boundaries using a watershed algorithm.

13. The computer system as recited in claim 11, wherein the processor performs the filtering of the raw data for reducing noise in the raw data.

14. The computer system as recited in claim 11, wherein the raw for each transparent capacitive sensing node of a touch screen corresponds to a data point, and the processor performs the filtering of the raw data for removing single data points that are not connected to other data points.

15. The computer system as recited in claim 11, wherein the processor calculates the coordinates of each touch region by calculating a centroid of each touch region with the digital raw data associated with each touch region.

16. A non-transitory computer readable medium including at least computer code executable by a computer, the computer executing the computer code for:

receiving raw data, the raw data including values for each transparent capacitive sensing node of a touch screen;

filtering the raw data;

generating gradient data;

calculating the boundaries for touch regions base on the gradient data; and

calculating the coordinates for each touch region.

17. The non-transitory computer readable medium as recited in claim 16, wherein the boundaries are calculated using a watershed algorithm.

18. The non-transitory computer readable medium as recited in claim 16, wherein filtering the raw data comprises reducing noise in the raw data.

19. The non-transitory computer readable medium as recited in claim 16, wherein the raw for each transparent capacitive sensing node of a touch screen corresponds to a data point, and filtering the raw data removes single data points that are not connected to other data points.

20. The non-transitory computer readable medium as recited in claim 16, wherein filtering the raw data generates filtered raw data, and the computer executing the computer code generates the gradient data is based on the filtered raw data.

21. The non-transitory computer readable medium as recited in claim 16, wherein the computer executing the computer code calculates the coordinates of each touch region by calculating a centroid of each touch region with the raw data associated with each touch region.