SYSTEM AND METHOD OF COMMUNICATION BETWEEN A CAPACITIVE TOUCH SCREEN AND AN ACTIVE STYLUS

• US 20160048234A1
• Filed: 08/18/2014
• Published: 02/18/2016
• Est. Priority Date: 08/18/2014
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Asia Pacific Pte Limited (STMicroelectronics NV)
• Inventors: Chandran, Praveesh, Noviello, Giuseppe, Cheong, Chee Weng, Guo, Dianbo, Tan, Kien Beng, Zhang, Chaochao, Karuppusamy, Baranidharan, Dinu, Leonard
• Granted Patent: US 9,703,433 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/0383 Signal control means within the pointing device
• 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 3/041661 using detection at multiple resolutions, e.g. coarse and fine scanning; using detection within a limited area, e.g. object tracking window
• CPC Class Codes: G06F 3/041662 using alternate mutual and self-capacitive scanning
• CPC Class Codes: G06F 3/0441 using active external devices, e.g. active pens, for receiving changes in electrical potential transmitted by the digitiser, e.g. tablet driving signals
• 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

An active stylus is capacitively coupled to a capacitive touch panel for communication. The active stylus operates in a wait mode to receive initial communications from the panel. In response to such receipt, the active stylus synchronizes to a repeating communications frame implementing time division multiplexing. Communications from the active stylus to the panel include: information communications; synchronization communications and communications specific for columns and/or rows of the panel. Communications from the panel to the active stylus may be addressed uniquely to the stylus or commonly to a group of styluses.

Claims

1. A method, comprising:

sending through a capacitive touch panel of a first signal during a first period of a repeating frame;

receiving by an active stylus capacitively coupled to the capacitive touch panel of the first signal;

sending by the active stylus of a second signal during a second period of said repeating frame; and

receiving through the capacitive touch panel of the second signal.

2. The method of claim 1, further comprising configuring the capacitive touch panel in a self-capacitance mode of operation, wherein the steps of sending and receiving are performed while the capacitive touch panel operates in the self-capacitance mode.

3. The method of claim 2, further comprising switching the capacitive touch panel between the self-capacitance mode and a mutual capacitance mode.

4. The method of claim 3, further comprising making by the capacitive touch panel of touch detections and touch location determinations during the mutual capacitance mode.

5. The method of claim 2, further comprising making by the capacitive touch panel of touch detections and touch location determinations during the self-capacitance mode by processing signal strength measurements made on the received second signal.

6. The method of claim 1, wherein the first signal is a wake-up signal and the second signal is a synchronization signal.

7. The method of claim 6, wherein the wake-up signal includes identification information common to a plurality of styluses and wherein the synchronization signal includes unique identification information for the responding active stylus.

8. The method of claim 7, further comprising comparing by the active stylus of the common identification information to a unique identification of the active stylus and wherein sending by the active stylus of the second signal comprises sending the second signal only if the common identification information corresponds to the unique identification.

9. The method of claim 6, wherein the wake-up signal includes identification information specific to a certain stylus, the method further comprising comparing by the active stylus of the specific identification information to a unique identification of the active stylus and wherein sending by the active stylus of the second signal comprises sending the second signal only if the specific identification information matches the unique identification.

10. The method of claim 1, wherein the first signal is a wake-up signal and the second signal comprises:

a stylus column signal communicating information to be received by columns of the capacitive touch panel and a stylus row signal communicating information to be received by rows of the capacitive touch panel.

11. The method of claim 10, further comprising:

operating the capacitive touch panel to scan panel columns during stylus transmission of the stylus column signal; and

operating the capacitive touch panel to scan panel row during stylus transmission of the stylus column signal.

12. The method of claim 1, further comprising:

modulating the first signal with information to be communicated from the capacitive touch panel to the active stylus; and

modulating the second signal with information to be communicated from the active stylus to the capacitive touch panel.

13. A method, comprising:

receiving by an active stylus capacitively coupled to a capacitive touch panel of a first signal transmitted through the capacitive touch panel during a first period of a repeating frame; and

sending by the active stylus of a second signal during a second period of said repeating frame for communication through the capacitive touch panel.

14. The method of claim 13, wherein the first signal is a wake-up signal and the second signal is a synchronization signal.

15. The method of claim 14, wherein the wake-up signal includes identification information common to a plurality of styluses and wherein the synchronization signal includes unique identification information for the active stylus.

16. The method of claim 15, further comprising comparing by the active stylus of the common identification information to a unique identification of the active stylus and wherein sending by the active stylus of the second signal comprises sending the second signal only if the common identification information corresponds to the unique identification.

17. The method of claim 15, wherein the wake-up signal includes identification information specific to a certain stylus, the method further comprising comparing by the active stylus of the specific identification information to a unique identification of the active stylus and wherein sending by the active stylus of the second signal comprises sending the second signal only if the specific identification information matches the unique identification.

18. The method of claim 13, wherein the first signal is a wake-up signal and the second signal comprises:

a stylus column signal communicating information to be received by columns of the capacitive touch panel and a stylus row signal communicating information to be received by rows of the capacitive touch panel.

19. The method of claim 13, further comprising modulating the second signal with information to be communicated from the active stylus to the capacitive touch panel.

20. A method, comprising:

sending using a capacitive touch panel of a first signal during a first period of a repeating frame to an active stylus capacitively coupled to the capacitive touch panel; and

receiving from the active stylus through the capacitive touch panel of a second signal during a second period of said repeating frame.

21. The method of claim 20, further comprising configuring the capacitive touch panel in a self-capacitance mode of operation, wherein the steps of sending and receiving are performed while the capacitive touch panel operates in the self-capacitance mode.

22. The method of claim 21, further comprising switching the capacitive touch panel between the self-capacitance mode and a mutual capacitance mode.

23. The method of claim 22, further comprising making by the capacitive touch panel of touch detections and touch location determinations during the mutual capacitance mode.

24. The method of claim 21, further comprising making by the capacitive touch panel of touch detections and touch location determinations during the self-capacitance mode by processing signal strength measurements made on received second signal.

25. The method of claim 20, wherein the first signal is a wake-up signal and the second signal is a synchronization signal.

26. The method of claim 25, wherein the wake-up signal includes identification information common to a plurality of styluses and wherein the synchronization signal is received from the active stylus having a unique identification corresponding to the common identification information, the second signal including the unique identification of the active stylus.

27. The method of claim 25, wherein the wake-up signal includes identification information specific to a certain stylus and wherein the synchronization signal is received from the active stylus having a unique identification matching the specific identification information.

28. The method of claim 20, wherein the first signal is a wake-up signal and the second signal comprises:

a stylus column signal communicating information to be received by columns of the capacitive touch panel and a stylus row signal communicating information to be received by rows of the capacitive touch panel.

29. The method of claim 28, further comprising:

operating the capacitive touch panel to scan panel columns during stylus transmission of the stylus column signal; and

operating the capacitive touch panel to scan panel row during stylus transmission of the stylus row signal.

30. The method of claim 20, further comprising modulating the first signal with information to be communicated from the capacitive touch panel to the active stylus.