Touch panel with adaptive noise reduction
AssigneeTektronix, Inc.
InventorRobert D. Meadows
Life of this patent
Estimating the term…
Abstract
A touch panel has panel scanning signals selectively applied to the four sides of a touch sensing surface of the panel so as to establish alternating current voltage gradients in desired directions across the touch sensing surface. When the panel is touched, touch signals result and are utilized by a touch location circuit in determining the location of touch. The impedance touch current resulting from a user's touch may also be determined and used. The touch panel circuit automatically filters the touch signals to an extent which varies depending upon the rate of movement of touch from one location on the touch sensing surface to a subsequent location. Filtering is decreased with the increasing rates of movement. The touch panel thereby minimizes the effects of noise on touch location determination.
Claims21
A method of reducing the effect of noise on the determination of the location at which a touch sensing surface of a touch panel is touched from touch signals generated in response to touching of the touch panel comprising:
- determining the rate of movement of touch on a touch sensing surface;
- filtering noise from the touch signals;
- and
- varying the extent of such filtering with changes in the rate of movement.
In a touch panel system having a touch sensing surface and touch signal generating means for generating touch signals in response to touch of the touch sensing surface, a touch signal processor for processing the touch signals to determine each of successive locations at which the touch sensing surface is touched, comprising:
- control means receiving the touch signals for determining a rate at which the successive locations on the touch sensing surface are touched and generating a control signal indicative of the rate;
- and
- dynamic filter means responsive to the control signal for filtering the touch signals in accordance with a selected one of multiple degrees of filtering.
In a touch panel system having a touch sensing surface and touch signal generating means for generating analog touch signals in response to touch of the touch sensing surface, a touch signal processor for processing the analog touch signals to determine successive locations at which the touch sensing surface is touched, comprising:
- converting means receiving the analog touch signals for converting them to digital touch signals;
- control means receiving the digital touch signals for determining a rate at which the successive locations on the touch sensing surface are touched and generating a control signal indicative of the rate;
- and
- dynamic filter means responsive to the control signal for filtering the digital touch signals in accordance with the rate at which the successive locations are touched.
Dependencies are inferred from the claim text.