CAPACITIVE TOUCH PANEL CONFIGURED TO SENSE BOTH ACTIVE AND PASSIVE INPUT WITH A SINGLE SENSOR

• US 20140347311A1
• Filed: 05/22/2013
• Published: 11/27/2014
• Est. Priority Date: 05/22/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Maxim Integrated Products, Inc. (Analog Devices, Inc.)
• Inventors: Joharapurkar, Ashutosh R., Tiruvuru, Rajesh
• Granted Patent: US 9,256,330 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• 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 3/0442 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: 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 capacitive touch panel includes sense electrodes arranged next to one another and drive electrodes arranged next to one another across the sense electrodes. The drive electrodes and the sense electrodes define a coordinate system where each coordinate location comprises a capacitor formed at a junction between one of the drive electrodes and one of the sense electrodes via mutual capacitance between the electrodes. The drive electrodes are configured to receive a first signal from a driver coupled with the drive electrodes for powering the drive electrodes to sense passive input to the capacitive touch panel at each coordinate location. Passive input can also be sensed via self-capacitance of the capacitive touch panel sensors. The drive electrodes and the sense electrodes are configured to receive a second signal from an active stylus to sense active input to the capacitive touch panel at each coordinate location.

Claims

1. A system comprising:

an active stylus; and

a capacitive touch panel comprising;

a plurality of sense electrodes arranged next to one another and

a plurality of drive electrodes arranged next to one another across the plurality of sense electrodes, the plurality of drive electrodes and the plurality of sense electrodes defining a coordinate system where each coordinate location comprises a capacitor formed at a junction between one of the plurality of drive electrodes and one of the plurality of sense electrodes, the plurality of drive electrodes configured to receive a first signal from a driver coupled with the plurality of drive electrodes for powering the plurality of drive electrodes to sense passive input to the capacitive touch panel at each coordinate location, and the plurality of drive electrodes and the plurality of sense electrodes configured to receive a second signal from the active stylus to sense active input to the capacitive touch panel at each coordinate location.

2. The system as recited in claim 1, further comprising a controller coupled with the plurality of drive electrodes, the controller configured to control the plurality of drive electrodes for sensing both the passive input and the active input.

3. The system as recited in claim 2, further comprising I and Q correlators configured to perform IQ demodulation to eliminate at least one of phase synchronization or frequency synchronization between the second signal transmitted from the active stylus and a demodulation/correlation signal generated by the controller.

4. The system as recited in claim 1, wherein sensing passive input to the capacitive touch panel and sensing active input to the capacitive touch panel is performed at least substantially simultaneously.

5. The system as recited in claim 1, wherein each one of the active stylus and the capacitive touch panel comprises a device configured to generate a stable reference frequency.

6. The system as recited in claim 1, wherein a characteristic frequency of the first signal is at least substantially different from a characteristic frequency of the second signal.

7. The system as recited in claim 1, wherein additional information comprising an indication of at least one of a pressure level or a button press is transmitted via the second signal.

8. a capacitive touch panel comprising:

a plurality of sense electrodes arranged next to one another; and

a plurality of drive electrodes arranged next to one another across the plurality of sense electrodes, the plurality of drive electrodes and the plurality of sense electrodes defining a coordinate system where each coordinate location comprises a capacitor formed at a junction between one of the plurality of drive electrodes and one of the plurality of sense electrodes, the plurality of drive electrodes configured to receive a first signal from a driver coupled with the plurality of drive electrodes for powering the plurality of drive electrodes to sense passive input to the capacitive touch panel at each coordinate location, and the plurality of drive electrodes and the plurality of sense electrodes configured to receive a second signal from an active stylus to sense active input to the capacitive touch panel at each coordinate location.

9. The capacitive touch panel as recited in claim 8, further comprising a controller coupled with the plurality of drive electrodes, the controller configured to control the plurality of drive electrodes for sensing both the passive input and the active input.

10. The capacitive touch panel as recited in claim 9, further comprising I and Q correlators configured to perform IQ demodulation to eliminate at least one of phase synchronization or frequency synchronization between the second signal transmitted from the active stylus and a demodulation/correlation signal generated by the controller.

11. The capacitive touch panel as recited in claim 8, wherein sensing passive input to the capacitive touch panel and sensing active input to the capacitive touch panel is performed at least substantially simultaneously.

12. The capacitive touch panel as recited in claim 8, wherein each one of the active stylus and the capacitive touch panel comprises a device configured to generate a stable reference frequency.

13. The capacitive touch panel as recited in claim 8, wherein a characteristic frequency of the first signal is at least substantially different from a characteristic frequency of the second signal.

14. The capacitive touch panel as recited in claim 8, wherein additional information comprising an indication of at least one of a pressure level or a button press is transmitted via the second signal.

15. A method, comprising:

driving a plurality of drive electrodes of a capacitive touch panel with a first signal from a driver coupled with the plurality of drive electrodes for powering the plurality of drive electrodes;

sensing passive input to the capacitive touch panel at a coordinate location comprising a capacitor formed at a junction between one of the plurality of drive electrodes and one of a plurality of sense electrodes arranged next to one another across the plurality of drive electrodes; and

sensing active input to the capacitive touch panel comprising a second signal from an active stylus using the plurality of drive electrodes and the plurality of sense electrodes at the coordinate location.

16. The method as recited in claim 15, wherein a controller is coupled with the plurality of drive electrodes and controls the plurality of drive electrodes for sensing both the passive input and the active input.

17. The method as recited in claim 16, wherein IQ demodulation is used to eliminate at least one of phase synchronization or frequency synchronization between the second signal transmitted from the active stylus and a demodulation/correlation signal generated by the controller.

18. The method as recited in claim 15, wherein the steps of sensing passive input to the capacitive touch panel and sensing active input to the capacitive touch panel are performed at least substantially simultaneously.

19. The method as recited in claim 15, wherein each one of the active stylus and the capacitive touch panel comprises a device configured to generate a stable reference frequency.

20. The method as recited in claim 15, wherein additional information comprising an indication of at least one of a pressure level or a button press is transmitted via the second signal.