Methods and Systems for Hybrid Multi-Touch Capacitive (MTC) and Active Stylus Touch Device

• US 20140184554A1
• Filed: 01/30/2013
• Published: 07/03/2014
• Est. Priority Date: 12/31/2012
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: WALLEY, John
• Granted Patent: US 9,448,670 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• 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 3/04162 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 3/04182 Filtering of noise external to the device and not generated by digitiser components
• 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

Embodiments for a hybrid multi-touch capacitive (MTC) and active stylus touch device are provided. Embodiments enable various ways for reusing system resources to enable simultaneous detection of conducting objects in contact with the device and/or active styluses in proximity to the device. In an embodiment, receiver channels are reused in a time multiplexed manner between an MTC mode and an active stylus mode of operation. In another embodiment, the use of system resources, including receiver channels, is adjusted based on the presence/absence of conducting objects and/or active styluses. Embodiments for improving the detection of conducting objects and/or active styluses are also provided, including embodiments for reducing the interference between conducting objects and active styluses.

Claims

1. A method of operating a system having a screen disposed above a grid comprising horizontal conductive lines and vertical conductive lines, the horizontal conductive lines coupled to respective driving lines and the vertical conductive lines coupled to respective sensing lines, the method comprising:

transmitting first signals on the driving lines in a first time interval of a periodic cycle;

receiving second signals on the sensing lines in response to the first signals in the first time interval of the periodic cycle;

processing the second signals to detect the presence of a conductive object in contact with the screen and an active stylus in proximity to the screen; and

if the active stylus is detected in proximity to the screen, receiving third signals on the driving lines and the sensing lines in a second time interval of the periodic cycle.

2. The method of claim 1, wherein the active stylus is detected, further comprising:

adjusting a transmit frequency of the first signals based on a signature of the detected active stylus.

3. The method of claim 2, wherein adjusting the transmit frequency of the first signals comprises increasing or decreasing the transmit frequency to reduce interference with a carrier frequency of the detected active stylus.

4. The method of claim 2, further comprising:

transmitting the first signals on the driving lines in the first time interval of the periodic cycle;

receiving the second signals on the sensing lines in response to the first signals in the first interval of the periodic cycle; and

receiving the third signals on the driving lines and the sensing lines in the second time interval of the periodic cycle.

5. The method of claim 1, wherein the active stylus is not detected, further comprising:

transmitting the first signals on the driving lines in the second time interval of the periodic cycle; and

receiving the second signals on the sensing lines in response to the first signals in the second time interval of the periodic cycle.

6. The method of claim 1, further comprising:

tuning a receiver filter based on the detected active stylus prior to receiving the third signals.

7. The method of claim 1, further comprising processing the third signals, wherein processing the third signals comprises:

determining a signal strength for one or more of the third signals;

determination a location of the active stylus based on the determined signal strength; and

data demodulating at least one of the third signals to retrieve information encoded in the third signals.

8. The method of claim 1, further comprising:

detecting the presence of the active stylus in proximity of the screen if the second signals include a matching signature of a known active stylus.

9. The method of claim 1, further comprising:

adjusting the first time interval and the second time interval based on the processing of the second signals.

10. A method of operating a system having a screen disposed above a grid comprising horizontal conductive lines and vertical conductive lines, the horizontal conductive lines coupled to respective driving lines and the vertical conductive lines coupled to respective sensing lines, the method comprising:

receiving first signals on a first set of the driving lines and the sensing lines;

determining whether or not an active stylus location is found based on the first signals;

if the active stylus location is found, selecting a second set of the driving lines and the sensing lines; and

receiving second signals on the second set of the driving lines and the sensing lines.

11. The method of claim 10, wherein the first set includes all driving lines and sensing lines.

12. The method of claim 10, wherein deter mining whether or not the active stylus is found comprises determining whether or not a two-dimensional position of an active stylus is found based on the first signals.

13. The method of claim 10, wherein selecting the second set of the driving lines and the sensing lines comprises selecting the second set based on the active stylus location.

14. The method of claim 13, wherein selecting the second set based on the active stylus location comprises selecting the second set to cover driving lines and sensing lines that run in an immediate vicinity of the active stylus location.

15. The method of claim 13, further comprising:

updating the active stylus location based on the second signals; and

updating the second set of the driving lines and the sensing lines based on the updated active stylus location.

16. The method of claim 10, wherein the second set is smaller than the first set.

17. A system, comprising:

a grid having a horizontal conductive line and a vertical conductive line, the horizontal conductive line coupled to a driving line and the vertical conductive line coupled to a sensing line;

a screen disposed above the grid;

a transmitter;

a receiver; and

a multiplexer configured to couple the transmitter to the driving line and the receiver to the sensing line during a first time interval of a periodic cycle and to couple the receiver to the driving line and to the sensing line during a second interval of the periodic cycle.

18. The system of claim 17, wherein the receiver comprises:

a filter configured according to a first configuration during the first time interval and a second configuration during the second time interval.

19. The system of claim 18, further comprising:

a noise measurement module configured to measure noise; and

a spectral estimation module configured to generate configuring parameters for the filter based on the measured noise.

20. The system of claim 18, further comprising:

a spectral estimation module configured to determine a transmit frequency for the transmitter.