Noise reduction in digitizer system

• US 9,372,575 B2
• Filed: 10/19/2015
• Issued: 06/21/2016
• Est. Priority Date: 02/27/2004
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Inventors: Perski, Haim, Rimon, Ori
• Primary Examiner(s): Karimi, Pegeman
• Application Number:
  US14/886,119
• Publication Number:
  US 20160041685A1
• Time in Patent Office: 246 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 2203/04106 Multi-sensing digitiser, i.e. digitiser using at least two different sensing technologies simultaneously or alternatively, e.g. for detecting pen and finger, for saving power or for improving position detection
• CPC Class Codes: G06F 2203/04108 Touchless 2D- digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface without distance measurement in the Z direction
• CPC Class Codes: G06F 3/03545 Pens or stylus
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• 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 3/04182 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 3/046 by electromagnetic means

Abstract

A method for noise reduction in a digitizer includes determining a location of a stylus with a known frequency of emission over a first sampling period, sampling output from a plurality of detecting elements over a second sampling period, identifying detecting elements with sampled output in the second sampling period above a defined threshold in a selected frequency, the selected frequency being close to but different than the known frequency of the stylus, selecting as a candidate carrier of mere noise a detecting element from the detecting elements identified that is spaced away from the determined location of the stylus, and reducing values of output sampled over the second sampling period from at least one other detecting element, in accordance with the output sampled over the second sampling period from the detecting element selected as the candidate carrier of mere noise.

Claims

1. A digitizer controller comprising:

a circuit configured to;

sample outputs from a plurality of sensor lines of a digitizer sensor substantially simultaneously to detect a signal emitted by a stylus interacting with the digitizer sensor;

identify based on the outputs, at least one sensor line of the plurality of sensor lines that sensed interaction with a conductive object;

determine a first level of output from the at least one sensor line in a frequency associated with emission from the stylus; and

adjust levels of the outputs from at least a portion of the plurality of sensor lines in the frequency associated with emission from the stylus based on the first level of output.

2. The digitizer controller of claim 1, wherein the circuit is configured to:

identify a sensor line that is least affected by the stylus; and

determine the first level of output from the sensor line that is least affected by the stylus.

3. The digitizer controller of claim 1, wherein the circuit is configured to:

identify a sensor line that provides a highest level of output in a frequency used for finger touch detection; and

determine the first level of output from the sensor line that provided the highest level of output in the frequency used for finger touch detection.

4. The digitizer controller of claim 3, wherein the circuit is configured to detect finger touch over a plurality of frequencies and wherein the highest level of output is detected in one of the plurality of frequencies that is closest to the frequency associated with emission from the stylus.

5. The digitizer controller of claim 1, wherein the circuit is configured to:

identify at least one other sensor line from the plurality of sensor lines, as a candidate carrier of a stylus signal; and

determine the first level of output from a sensor line that is beyond a determined distance from the at least one other sensor line.

6. The digitizer controller of claim 1, wherein the circuit is configured to:

identify based on the outputs, at least one other sensor line from the plurality of sensor lines as a candidate carrier of a stylus signal;

determine a ratio between level of output from the at least one sensor line and the at least one other sensor line, both in a frequency used for finger touch detection;

from the ratio and the first level of output, determine a noise level at the frequency associated with emission from the stylus at the candidate carrier of the stylus signal; and

adjust the levels of the outputs based on the noise level.

7. The digitizer controller of claim 1, wherein the circuit is configured to determine a position of the stylus based on the levels of the outputs as adjusted.

8. The digitizer controller of claim 1, wherein the circuit is configured to detect a position of a finger interacting with the digitizer sensor.

9. A digitizer controller comprising:

a circuit configured to;

sample outputs from a plurality of sensor lines of a digitizer sensor substantially simultaneously to detect a signal emitted by a stylus interacting with the digitizer sensor;

identify based on the outputs, a first group of sensor lines of the plurality of sensor lines that sensed interaction with a conductive object;

determine a first level of output from the first group in a frequency associated with emission from the stylus;

adjust levels of the outputs from at least a portion of the plurality of sensor lines in the frequency associated with emission from the stylus based on the first level of output; and

identify based on the adjust levels of the outputs, a second group of sensor lines that sensed interaction with a conductive object;

determine a position of the stylus based on the second group.

10. The digitizer controller of claim 9, wherein the circuit is configured to:

identify a sensor line from the first group that provides a highest level of output in a frequency used for finger touch detection; and

determine the first level of output from the sensor line that provided the highest level of output in the frequency used for finger touch detection.

11. The digitizer controller of claim 9, wherein the circuit is configured to:

identify at least one other sensor line from the plurality of sensor lines, as a candidate carrier of a stylus signal; and

determine the first level of output from a sensor line that is beyond a determined distance from the at least one other sensor line.

12. The digitizer controller of claim 9, wherein the circuit is configured to detect a position of a finger interacting with the digitizer sensor.

13. A digitizer system comprising:

a display configured to display data;

a digitizer sensor integrated with the display, wherein the digitizer sensor is configured to detect interaction with each of a stylus and a finger;

a controller configured to operate the digitizer sensor, wherein the controller includes a circuit configured to;

sample outputs from a plurality of sensor lines of a digitizer sensor substantially simultaneously to detect a signal emitted by a stylus interacting with the digitizer sensor;

identify based on the outputs, at least one sensor line of the plurality of sensor lines that sensed interaction with a conductive object;

determine a first level of output from the at least one sensor line in a frequency associated with emission from the stylus; and

adjust levels of the outputs from at least a portion of the plurality of sensor lines in the frequency associated with emission from the stylus based on the first level of output.

14. The digitizer controller of claim 13, wherein the circuit is configured to:

identify a sensor line that is least affected by the stylus; and

determine the first level of output from the sensor line that is least affected by the stylus.

15. The digitizer controller of claim 13, wherein the circuit is configured to:

identify a sensor line that provides a highest level of output in a frequency used for finger touch detection; and

determine the first level of output from the sensor line that provided the highest level of output in the frequency used for finger touch detection.

16. The digitizer controller of claim 13, wherein the circuit is configured to:

identify at least one other sensor line from the plurality of sensor lines, as a candidate carrier of a stylus signal; and

determine the first level of output from a sensor line that is beyond a determined distance from the at least one other sensor line.

17. The digitizer controller of claim 13, wherein the circuit is configured to:

identify based on the outputs, at least one other sensor line from the plurality of sensor lines as a candidate carrier of a stylus signal;

determine a ratio between level of output from the at least one sensor line and the at least one other sensor line, both in a frequency used for finger touch detection;

from the ratio and the first level of output, determine a noise level at the frequency associated with emission from the stylus at the candidate carrier of the stylus signal; and

adjust the levels of the outputs based on the noise level.

18. The digitizer controller of claim 13, wherein the circuit is configured to determine a position of the stylus based on the levels of the outputs as adjusted.

19. The digitizer system of claim 13, wherein the digitizer sensor is a grid based capacitive sensor.

20. The digitizer system of claim 13, wherein the controller is configured to detect simultaneous and separate inputs from the stylus and a user finger.