Adaptive thresholding for touch screen input
AssigneeTexas Instruments Incorporated
InventorBaboo Vikrhamsingh Gowreesunker
Life of this patent
Estimating the term…
Abstract
An adaptive threshold approach is applied to detect true touch signals and filter out increased noise signals. More specifically, statistics regarding the signals from a touch screen are used to create a touch signal threshold that changes with the statistics of the touch signals. Accordingly, the threshold can automatically move higher in high noise situations and lower in low noise situations. So configured, fewer noise signals are erroneously interpreted as touches for the device associated with the touch screen.
Claims13
An apparatus for detecting a touch on a touch screen, the apparatus comprising:
- a processing device configured to connect to receive individual signals from a touch screen configured to provide the individual signals from corresponding pixels of the touch screen, wherein the individual signals correspond to whether a touch occurs on a surface of the touch screen at the corresponding pixels, wherein the processing device is configured to:
- partition the touch screen into a touch area and a no-touch area based on the individual signals,
- estimate touch statistics corresponding to the touch area,
- estimate noise statistics corresponding to the no-touch area,
- estimate a touch threshold using the touch statistics and the noise statistics,
- create a touch map using the touch threshold, wherein the touch map is configured to indicate specific portions of the touch screen that are touched for use as a real-time input signal for a device associated with the touch screen.
A method of detecting a touch signal on a touch screen, the method comprising:
- creating individual signals from corresponding pixels of the touch screen, wherein the individual signals correspond to whether a touch occurs on a surface of the touch screen at the corresponding pixels;
- using a processing device connected to receive the individual signals to:
- partition the touch screen into a touch area and a no-touch area based on the individual signals,
- estimate touch statistics corresponding to the touch area,
- estimate noise statistics corresponding to the no-touch area,
- estimate a touch threshold using the touch statistics and the noise statistics,
- create a touch map using the touch threshold,
- use the touch map to indicate specific portions of the touch screen that are touched for use as a real-time input signal for a device associated with the touch screen.
An apparatus for detecting a touch on a touch screen, the apparatus comprising:
- a touch screen configured to provide individual signals from corresponding pixels of the touch screen, wherein the individual signals correspond to whether a touch occurs on a surface of the touch screen at the corresponding pixels;
- a processing device configured to connect to receive the individual signals from the touch screen, wherein the processing device is configured to:
- calculate a mean signal value and a variance value for individual rows and/or individual columns of the pixels;
- determine a touch row and/or a touch column as having a highest or near highest variance;
- determine a no-touch row and/or a no-touch column as having a lowest or near lowest variance,
- estimate touch statistics corresponding to the touch area by determining a touch maximum signal value for the touch row and/or the touch column,
- estimate noise statistics corresponding to the no-touch area by determining a no-touch average signal value for the no-touch row and/or the no-touch column and determining a no-touch variance value for the no-touch row and/or the no-touch column,
- estimate a touch threshold using the touch statistics and the noise statistics by:
- determining a dynamic range for the touch screen by subtracting the no-touch average signal value from the touch maximum signal value, and
- determining the touch threshold according to a function of the no-touch average signal value, the no-touch variance value, and the dynamic range,
- create a touch map using the touch threshold by ignoring individual signals less than the touch threshold, wherein the touch map is configured to indicate specific portions of the touch screen that are touched for use as a real-time input signal for a device associated with the touch screen.
Dependencies are inferred from the claim text.