ACTIVE STYLUS

• US 20120327041A1
• Filed: 06/22/2011
• Published: 12/27/2012
• Est. Priority Date: 06/22/2011
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: HARLEY, Jonah A., Simon, David I.
• Granted Patent: US 8,928,635 B2
• Time in Patent Office: Days
• US Class Current: 345/179
• CPC Class Codes: G06F 2203/04112 Electrode mesh in capacitive digitiser: electrode for touch sensing is formed of a mesh of very fine, normally metallic, interconnected lines that are almost invisible to see. This provides a quite large but transparent electrode surface, without need for ITO or similar transparent conductive material
• 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 3/0441 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 3/0445 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

An active stylus is disclosed. The stylus includes an electrode at a tip of the stylus; and powered circuitry coupled to the electrode and configured for capacitively coupling the electrode with a capacitive touch sensor panel. The powered circuitry can further include drive circuitry configured to output a drive voltage at the electrode and/or sense circuitry configured to sense a voltage received at the electrode.

Claims

1. An active stylus, comprising:

an electrode at a tip of the stylus; and

powered circuitry coupled to the electrode and configured for capacitively coupling the electrode with a capacitive touch sensor panel.

2. The active stylus of claim 1, wherein the powered circuitry comprises:

drive circuitry configured to output a drive voltage at the electrode.

3. The active stylus of claim 1, further comprising a power source coupled to the powered circuitry for supplying power to the powered circuitry.

4. The active stylus of claim 2, wherein the drive circuitry further comprises:

a clock to generate a drive voltage;

a microcontroller connected to the clock and configured to control the drive voltage; and

an amplifier connected to the microcontroller and configured to adjust the drive voltage.

5. The active stylus of claim 1, wherein the powered circuitry comprises:

sense circuitry configured to sense a voltage received at the electrode.

6. The active stylus of claim 5, the sense circuitry further comprising an amplifier to adjust the sensed voltage.

7. The active stylus of claim 6, wherein the sense circuitry further comprises:

a clock to generate a demodulation signal;

a phase shifter to shift the phase of the demodulation signal; and

a set of mixers to receive the sensed voltage and either the demodulation signal or the phase-shifted demodulation signal to demodulate the sensed voltage.

8. The active stylus of claim 7, wherein the mixer receiving the demodulation signal produces an in-phase component;

wherein the mixer receiving the phase-shifted demodulation signal produces a quadrature component; and

wherein the in-phase component and the quadrature component are combined to determine an amplitude proportional to a capacitance formed by the electrode.

9. The active stylus of claim 1, the active stylus incorporated into a touch-based input system, the system comprising:

a capacitive touch sensor panel including a plurality of sense lines; and

one or more sense channels coupled to the plurality of sense lines, the one or more sense channels configured for detecting a change in capacitance between the electrode and one or more sense lines to determine a location of a touch by the active stylus on the touch sensor panel.

10. The active stylus of claim 9, wherein the electrode is stimulated at a frequency to identify the presence of the stylus.

11. The active stylus of claim 8, wherein the electrode is stimulated with a pattern that identifies a presence of the stylus.

12. The active stylus of claim 9, wherein the one or more sense channels comprise at least one row channel and at least one column channel.

13. The active stylus of claim 9, wherein the active stylus further comprises:

a clock to generate a drive voltage;

a microcontroller connected to the clock and configured to control the drive voltage; and

an amplifier connected to the microcontroller and configured to adjust the drive voltage.

14. The active stylus of claim 9, wherein one or more sense channels comprise:

a sense amplifier to adjust a detected change in capacitive coupling;

a clock to generate a demodulation signal;

a phase shifter to shift a phase of the demodulation signal; and

a set of mixers to receive the detected change in capacitive coupling and either the demodulation signal or the phase-shifted demodulation signal to demodulate the sensed voltage.

15. The active stylus of claim 14, wherein the mixer receiving the demodulation signal produces an in-phase component;

wherein the mixer receiving the phase-shifted demodulation signal produces a quadrature component; and

wherein the in-phase component and the quadrature component are combined to determine an amplitude proportional to a capacitance formed by the drive channel and the sense channel.

16. The active stylus of claim 9, wherein the capacitive touch sensor panel is in communication with the stylus via one of a physical cable and a wireless channel.

17. The active stylus of claim 9, wherein the capacitive touch sensor panel further comprises at least one drive line configured to generate a signal that can be sensed by at least one of the sense channels.

18. The active stylus of claim 5, the active stylus incorporated into a touch-based input system, the system comprising:

a capacitive touch sensor panel including a plurality of drive lines; and

one or more drive channels coupled to the plurality of drive lines, wherein an identity of a drive line being stimulated by a drive channel is used to determine a location of a touch by the active stylus on the touch sensor panel.

19. The active stylus of claim 18, wherein the stylus further comprises an amplifier to adjust the sensed voltage.

20. The active stylus of claim 19, wherein the stylus further comprises:

a clock to generate a demodulation signal;

a phase shifter to shift the phase of the demodulation signal; and

a set of mixers to receive the sensed voltage and either the demodulation signal or the phase-shifted demodulation signal to demodulate the sensed signal.

21. The active stylus of claim 20, wherein the mixer receiving the demodulation signal produces an in-phase component;

wherein the mixer receiving the phase-shifted demodulation signal produces a quadrature component; and

wherein the in-phase component and the quadrature component are combined to determine an amplitude proportional to a capacitance formed by a drive channel and the electrode.

22. The active stylus of claim 18, wherein the capacitive touch sensor panel is in communication with the stylus via one of a physical cable and a wireless channel.

23. The active stylus of claim 18, wherein a signal from each of the drive channels can be distinguished by a unique code.

24. A stylus touch detection method, comprising:

capacitively coupling a powered electrode in the stylus with a touch sensor panel by forming a mutual capacitance between the electrode and the touch sensor panel to detect a stylus touch on the touch sensor panel.

25. The method of claim 24, further comprising:

generating a stimulation signal at the powered electrode; and

detecting the stylus touch on the touch sensor panel upon detection of a capacitively coupled stimulation signal on a sense line in the touch sensor panel.

26. The method of claim 25, further comprising:

generating a stimulation signal in the touch sensor panel; and

detecting the stylus touch on the touch sensor panel upon detection of a capacitively coupled stimulation signal on a sense circuit in the stylus.