NOISE REDUCTION IN DIGITIZER SYSTEM

• US 20110254807A1
• Filed: 06/29/2011
• Published: 10/20/2011
• Est. Priority Date: 02/27/2004
• Status: Abandoned Application

• Current Assignee: N-Trig Ltd (Microsoft Corporation)
• Original Assignee: N-Trig Ltd (Microsoft Corporation)
• Inventors: PERSKI, Haim, Rimon, Ori
• Application Number:
  US13/171,601
• Publication Number:
  US 20110254807A1
• Time in Patent Office: Days
• US Class Current: 345/174
• 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 digitizer that includes plurality of detecting elements for detecting an electromagnetic signal. A method for noise reduction in the digitizer includes determining a location of a stylus with a known frequency of emission over a first sampling period, sampling output from the plurality of detecting elements substantially simultaneously over a second sampling period, the second sampling period subsequent to the first sampling period, identifying detecting elements with output above a defined threshold in a selected frequency that is close to but different than the known frequency, wherein the detecting elements identified are identified based on the output sampled over the second sampling period, selecting from the detecting elements identified in the second sampling period, a detecting element that is spaced away from the location of the stylus, wherein the detecting element selected is selected as a candidate carrier of mere noise, and reducing output sampled in the second sampling period of at least one other detecting element in accordance with output of the detecting element selected as a candidate carrier of mere noise.

Claims

1. A method for noise reduction in a digitizer, the digitizer comprising a plurality of detecting elements for detecting an electromagnetic signal, comprising:

determining a location of a stylus with a known frequency of emission over a first sampling period;

sampling output from the plurality of detecting elements substantially simultaneously over a second sampling period, the second sampling period subsequent to the first sampling period;

identifying detecting elements with output above a defined threshold in a selected frequency that is close to but different than the known frequency, wherein the detecting elements identified are identified based on the output sampled over the second sampling period;

selecting from the detecting elements identified in the second sampling period, a detecting element that is spaced away from the location of the stylus, wherein the detecting element selected is selected as a candidate carrier of mere noise; and

reducing values of output sampled in the second sampling period of at least one other detecting element, in accordance with output of the detecting element selected as a candidate carrier of mere noise.

2. The method of claim 1, comprising locating the stylus in a second sampling period based on a signal level of the reduced value of output of the at least one other detecting element.

3. The method of claim 1, comprising detecting from each of the plurality of detecting element, output in the selected frequency and output in the known frequency.

4. The method of claim 1, comprising utilizing signal level of output in the selected frequency to estimate a noise level in the known frequency of the stylus.

5. The method of claim 1, wherein output of candidate carrier of mere noise is at least in part a consequence of presence of any member of a group of:

a finger, hand or palm.

6. The method of claim 1, wherein said digitizer is adapted for finger touch detection and wherein the selected frequency is a frequency used for said finger touch detection.

7. The method of claim 1, wherein the detecting element that is spaced away from the location of the stylus is spaced away from the location of the stylus by a distance that is above a predefined distance.

8. The method of claim 1, wherein the detecting element selected from the detecting elements identified is a detecting element that is furthest from the location of the stylus.

9. The method of claim 1, wherein the selected frequency is a frequency within a defined range of frequencies around the known frequency of the stylus.

10. The method of claim 9, wherein the selected frequency is a frequency having a highest level output in the defined range.

11. The method of claim 1 further comprising:

detecting output in each of a plurality of frequencies within a defined range of frequencies around the known frequency of the stylus; and

defining the selected frequency as a frequency with a highest output from the output in each of the plurality of frequencies.