US5053757A — Touch panel with adaptive noise reduction

Claim 1

Independent Claim 71 words

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.

Claim 2

Independent Claim 71 words

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.

Claim 3

Dependent Claim 57 words

A method according to claim 1 in which the step of filtering noise comprises the step of digitally filtering digital touch signals and the step of determining the rate of movement comprises the steps of computing the distance traveled from a first determined touch location to a subsequent determined touch location over a known period of time.

Claim 4

Dependent Claim 49 words

A method according to claim 2 in which the step of varying the extent of such filtering comprises the steps of establishing ranges of computed distances and modifying the determined touch location as a function of the specific range of computed distances in which a particular computed distance falls.

Claim 5

Dependent Claim 66 words

A method according to claim 1 in which the step of filtering noise comprises averaging samples of touch signals to filter noise from such signals and the step of determining the rate of movement comprises the steps of computing the distance from a first determined touch location to a second determined touch location and increasing the number of samples that are averaged with decreasing computed distances.

Claim 6

Dependent Claim 108 words

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.

Claim 7

Dependent Claim 108 words

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.

Claim 8

Dependent Claim 47 words

The processor of claim 5 in which the control means includes a microcontroller that determines the rate at which the successive locations are touched and generates a corresponding rate signal, and a decoder that receives and is responsive to the rate signal for generating the control signal.

Claim 9

Dependent Claim 25 words

The processor of claim 5 in which the selected degree of filtering is inversely related to the rate at which the successive locations are touched.

Claim 10

Dependent Claim 53 words

The processor of claim 5 in which the touch signal includes signal components of multiple frequencies and the degree of filtering provided by the dynamic filter means is responsive to the control signal for attenuating higher frequency signal components by amounts inversely proportional to the rate at which the successive locations are touched.

Claim 11

Dependent Claim 59 words

The processor of claim 5 in which the control means further associates predefined ranges of rates with respective ones of the multiple degrees of filtering, correlates the rate at which the successive locations are touched with a corresponding range of rates, and generates a control signal to provide the degree of filtering associated with the corresponding range of rates.

Claim 12

Dependent Claim 61 words

The processor of claim 5 in which the touch signal generating means generates the touch signals in an analog format, the processor further comprising converting means for converting the touch signals in the analog format to touch signals in a digital format and for delivering the touch signals in the digital format to the control means and the dynamic filter means.

Claim 13

Dependent Claim 75 words

The processor of claim 5 in which the control means periodically identifies and computes a distance between successive pairs of the locations at which the touch sensing surface is touched to determine the rate of movement, each successive pair including a former locations and a latter location, and in which the dynamic filter means modifies the latter of each successive pair of locations in response to the touch distance, thereby to filter the touch signals.

Claim 14

Dependent Claim 98 words

The processor of claim 11 in which the control means correlates the periodically computed touch distance with a corresponding one of multiple predefined ranges of distances and includes a stored table of n-number of filter modifiers K i , i=1, 2, . . . , n, each filter modifier K i being associated with a distinct one of the predefined ranges of distances, the control means further selecting the filter modifier K i associated with the computed touch distance and modifying the touch location determination as a function of the selected K i to filter the touch signals.

Claim 15

Dependent Claim 106 words

The processor of claim 12 in which locations on the touch sensing surface are defined with reference to X- and Y-axis coordinates of a Cartesian coordinate system and the control means identifies and modifies the touch locations such that: X.sub.mod =(1-K.sub.i)X.sub.old +(K.sub.i)X.sub.detected Y.sub.mod =(1=K.sub.i)Y.sub.old +(K.sub.i)Y.sub.detected wherein X old and Y old are the respective modified X- and Y-axis coordinates of the former touch location, X mod and Y mod are the respective modified X- and Y-axis coordinates of the latter touch location, and X detected and Y detected are the respective X- and Y-axis coordinates of the latter touch location initially identified by the control means.

Claim 16

Dependent Claim 62 words

The processor of claim 13 in which: K.sub.1 =1, if D≧16 K.sub.2 =1/2, if 16>D≧8 K.sub.3 =1/4, if 8>D≧4 K.sub.4 =1/8, if 4>D≧2 K.sub.5 =1/16, if 2>D≧0 wherein D is the absolute value of the coordinate distance between the modified coordinates of a former touch location and the initially identified coordinates of a latter touch location initially identified by the control means.

Claim 17

Dependent Claim 28 words

The processor of claim 14 in which K i is reset to a value of 1 after a predetermined period during which the touch sensing surface is untouched.

Claim 18

Dependent Claim 125 words

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.

Claim 19

Dependent Claim 125 words

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.

Claim 20

Dependent Claim 29 words

The processor of claim 16 in which the dynamic filter means provides filtering of the digital touch signals in accordance with a selected one of multiple degrees of filtering.

Claim 21

Dependent Claim 60 words

The processor of claim 16 in which the control means further associates multiple predefined ranges of rates with respective ones of the multiple degrees of filtering, correlates the rate at which the successive locations are touched with a corresponding range of rates, and generates a control signal to provide the degree of filtering associated with the corresponding range of rates.

Claim 22

Dependent Claim 47 words

The processor of claim 16 in which the control means includes a microcontroller that determines the rate at which the successive locations are touched and generates a corresponding rate signal, and a decoder that receives and is responsive to the rate signal for generating the control signal.

Claim 23

Dependent Claim 25 words

The processor of claim 16 in which the selected degree of filtering is inversely related to the rate at which the successive locations are touched.

Claim 24

Dependent Claim 75 words

The processor of claim 16 in which the control means periodically identifies and computes a distance between successive pairs of the locations at which the touch sensing surface is touched to determine the rate of movement, each successive pair including a former location and a latter location, and in which the dynamic filter means modifies the latter of each successive pair of locations in response to the touch distance, thereby to filter the touch signals.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1994-09-30	1995-04-01	1995-10-01	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1998-09-30	1999-04-01	1999-10-01	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2002-09-30	2003-04-01	2003-10-01	$7700.00	Window Closed / Lapsed

Touch panel with adaptive noise reduction

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