Scan engine for touch controller architecture

• US 9,939,935 B2
• Filed: 07/16/2014
• Issued: 04/10/2018
• Est. Priority Date: 07/31/2013
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Shahparnia, Shahrooz
• Primary Examiner(s): Olson, Jason C
• Application Number:
  US14/333,382
• Publication Number:
  US 20150035797A1
• Time in Patent Office: 1,364 Days
• Field of Search: 345174
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• 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 3/044 by capacitive means
• 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 3/0443 using a single layer of sensing electrodes
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

A touch controller that can configure touch circuitry according to a scan plan, which can define a sequence of scan events to be performed on a touch panel is disclosed. The touch controller can include a configurable transmit section to generate stimulation signals to drive the panel, a configurable receive section to receive and process touch signals from the panel, and a configurable memory to store the touch signals. The touch controller can also include a programmable scan engine to configure the transmit section, the receive section, and the memory according to the scan plan. The touch controller advantageously provides more robust and flexible touch circuitry to handle various types of touch events at the panel. An active stylus that can generate stimulation signals that can be detected by the touch controller during various touch events at the panel is also disclosed.

Claims

1. A touch sensitive device comprising:

a configurable circuit capable of switching a coupling of a touch sensor panel comprising a plurality of row traces and a plurality of column traces to components of the circuit in a transmit configuration or components of the circuit in a receive configuration, the transmit configuration capable of generating stimulation signals having one or more phases and one or more frequencies to drive the touch sensor panel to detect a touch or hover event by an object, and the receive configuration capable of receiving and processing a touch signal indicative of the detected touch or hover event; and

a scan engine capable of configuring the circuit according to a scan plan, the scan plan defining a sequence of scan events to be performed at the touch sensor panel, the scan events including at least two different scan types selected from a group of a mutual capacitance scan, a self-capacitance scan and a stylus scan, each scan event defining the transmit configuration and the receive configuration for the scan event, and executing the scan plan to perform the sequence of scan events with the defined transmit and receive configurations for the scan events;

wherein the touch sensor panel is configured to be driven with the stimulation signals generated by components of the circuit in the transmit configuration during the mutual capacitance scan and during the self-capacitance scan; and

wherein the scan engine is capable of configuring the circuit to transmit the stimulation signals to the non-inverting input of sense amplifiers and to receive the touch signal from the row traces or the column traces in the receive configuration during the self-capacitance scan, the row traces or the column traces in the receive configuration coupled to the inverting input of the sense amplifiers, the touch signal indicating a self-capacitance between the row traces or the column traces and an object proximate to the touch sensor panel.

2. The device of claim 1, wherein the circuit is capable of driving a first portion of the touch sensor panel with one of the stimulation signals having a first frequency and receiving at least a first touch signal from the first portion, and simultaneously driving a second portion of the touch sensor panel with another of the stimulation signals having a second frequency and receiving at least a second touch signal from the second portion.

3. The device of claim 1, wherein the touch sensor panel comprises a plurality of touch nodes, each touch node capable of receiving the stimulation signals from the components of the circuit in the transmit configuration and transmitting the touch signals to the components of the circuit in the receive configuration.

4. The device of claim 1, wherein the scan engine is capable of configuring the circuit to transmit the stimulation signals to the plurality of row traces in the transmit configuration and to receive the touch signal from the plurality of column traces in the receive configuration, the touch signal indicating a mutual capacitance between the row traces and the column traces.

5. The device of claim 1, wherein the scan engine is capable of configuring the circuit to transmit the stimulation signals to a first set of the row traces in the transmit configuration and to receive the touch signal from a second set of the row traces in the receive configuration, the touch signal indicating a mutual capacitance between the first and second sets of the row traces.

6. The device of claim 5, wherein the scan engine is capable of configuring the circuit to ground one or more row traces between the first set of row traces in the transmit configuration and the second set of row traces in the receive configuration.

7. The device of claim 1, wherein the scan engine is capable of configuring the circuit to transmit the stimulation signals to a first set of the column traces in the transmit configuration and to receive the touch signal from a second set of the column traces in the receive configuration, the touch signal indicating a mutual capacitance between the first and second sets of the column traces.

8. The device of claim 7, wherein the scan engine is capable of configuring the circuit to ground one or more column traces between the first set of column traces in the transmit configuration and the second set of column traces in the receive configuration.

9. The device of claim 1, wherein the scan engine is further capable of configuring the circuit to transmit a guard signal to the column traces in the transmit configuration, the column traces acting as a guard to block interference to the touch signal at the row traces.

10. The device of claim 1, wherein the scan engine is further capable of configuring the circuit to transmit a guard signal to the row traces in the transmit configuration, the row traces acting as a guard to block interference to the touch signal at the column traces.

11. The device of claim 1, further comprising:

a display capable of displaying first data and updating to display second data;

wherein the scan engine is capable of receiving a display signal indicating that the display is updating and configuring the circuit to operate on the touch sensor panel during the updating of the display.

12. The device of claim 1, wherein the circuit is capable of switching the components to a cancelation configuration, the cancelation configuration being capable of canceling parasitic capacitance from the touch signal.

13. The device of claim 1, wherein the circuit comprises two configurable circuits coupled together in a master-slave configuration, each of the two circuits being capable of operating in a transmit configuration and a receive configuration.

14. The device of claim 1, wherein the scan engine is capable of configuring the circuit to receive a noise signal from the plurality of column traces in the receive configuration and the plurality of row traces in the receive configuration when the circuit is not generating stimulation signals.

15. The device of claim 14, wherein the noise signal is demodulated at one or more frequencies.

16. The device of claim 14, wherein the noise signal is demodulated using one or more in-phase (I) and quadrature (Q) demodulators.

17. The device of claim 14, wherein the noise signal is demodulated using a demodulation window corresponding to stimulation signals generated during a scan event.

18. The device of claim 15, wherein a noise value is generated from the demodulated noise signal at the one or more frequencies and one or more low noise frequencies are determined by selecting the one or more frequencies with the smallest noise value.

19. The device of claim 18, further comprising wireless communication circuitry capable of transmitting, to a peripheral device, at least one of information about the one or more low noise frequencies, information about the scan plan, or device clock information.

20. The device of claim 19, wherein the wireless communication circuitry is further capable of receiving force information from the peripheral device.

21. The device of claim 1, wherein configuring the circuit includes coupling the plurality of row traces and the plurality of column traces to transmit or receive channels.

22. The device of claim 21, wherein a row trace and a column trace are paired with a transmit channel and receive channel pair, such that one of the row trace and the column trace can be coupled to a transmit channel of the transmit channel and receive channel pair and the other of the row trace and the column trace can be coupled to a receive channel of the transmit channel and receive channel pair.