Controller for an acoustic wave touch panel

Claim 2

A controller for an acoustic wave touch panel having a substrate, X axis transducer means for imparting acoustic waves into said substrate for propagation therein relative to an associated X axis, said X axis transducer means receiving acoustic waves incident thereto to generate an X axis signal representing sensed acoustic waves from which the position of a touch relative to said X axis can be determined and a Y axis transducer means for imparting acoustic waves into said substrate for propagation therein relative to an associated Y axis, said Y axis transducer means receiving acoustic waves incident thereto to generate a Y axis signal representing sensed acoustic waves from which the position of a touch relative to said Y axis can be determined, said controller comprising: a signal conditioning circuit responsive to an X axis signal and a Y axis signal simultaneously received by said circuit for rejecting common modes from said signals to provide conditioned X axis and Y axis signals; means for converting said conditioned X axis signal to a plurality of discrete X axis magnitude values, each value being associated with a position along said X axis, said converting means converting said conditioned Y axis signal to a plurality of discrete Y axis magnitude values, each value being associated with a position along said Y axis; means for comparing each of a plurality of said X axis magnitude values to a reference X axis value associated with the same position with respect to said X axis as the position of said X axis magnitude value to provide an X-axis difference value representing the difference between said compared X axis values, said comparing means comparing each of a plurality of said Y axis magnitude values to a reference Y axis value associated with the same position with respect to said Y axis as the position of said Y axis magnitude value to provide a Y axis difference value representing the difference between said compared Y axis values; and means for determining the position of a touch from a plurality of X axis difference values associated with X axis positions within a given range of the X axis position along the X axis associated with a maximum X axis difference value and from a plurality of Y axis difference values associated with X axis positions within a given range of the X axis position associated with a maximum Y axis difference value.

Claim 3

A controller for an acoustic wave touch panel as recited in claim 1 wherein said touch position determining means includes a low pass filter for filtering a plurality of said X axis difference values within said range of said maximum X axis difference value and a plurality of said Y axis difference values within a range of said maximum Y axis difference values to provide respective X axis filtered values and Y axis filtered values; and a peak detector for detecting a peak of said X axis filtered values and a peak of said Y axis filtered values, said X axis peak and Y axis peak representing the position of a touch with respect to said X and Y axes.

Claim 4

A controller for an acoustic wave touch panel as recited in claim 1 including a touch pressure detector for detecting the pressure of a touch from said maximum X axis difference value and said maximum Y axis difference value.

Claim 5

A controller for an acoustic wave touch panel as recited in claim 3 wherein said touch pressure detector includes means for averaging said magnitudes of said maximum difference signals associated with said X and Y axes.

Claim 6

A controller for ant acoustic wave touch panel as recited in claim 1 wherein said signal conditioning circuit includes an amplifier with an adjustable gain and further including means for automatically adjusting the gain of said amplifier.

Claim 7

A controller for an acoustic wave touch panel as recited in claim 5 wherein said gain adjustment means includes means for comparing a difference value associated with a preselected position along the X axis to a gain reference value associated with said preselected position, said gain adjustment means adjusting said gain if said difference value is not within a given range of said gain reference value.

Claim 8

A controller for an acoustic wave touch panel as recited in claim 6 including means for automatically selecting said preselected position upon an initialization of said touch panel from the position of a maximum X axis difference value determined for an untouch panel.

Claim 9

A controller for an acoustic wave touch panel as recited in claim 6 including means for updating said X axis reference values if said gain is adjusted.

Claim 10

A controller for an acoustic wave touch panel as recited in claim 6 wherein said gain adjustment means includes means for comparing a difference value associated with a preselected position along the Y axis to a gain reference value associated with said preselected position, said gain adjustment means adjusting said gain for said Y axis if said difference value is not within a given range of said gain reference value.

Claim 11

A controller for an acoustic wave touch panel as recited in claim 9 including means for automatically selecting said preselected position upon an initialization of said touch panel from the position of a maximum Y axis difference value determined for an untouch panel.

Claim 12

A controller for an acoustic wave touch panel as recited in claim 9 including means for updating said Y axis reference values if said gain is adjusted.

Claim 13

A controller for an acoustic wave touch panel having a substrate, X axis transducer means for imparting acoustic waves into said substrate for propagation therein relative to an associated X axis, said X axis transducer means receiving acoustic waves incident thereto to generate an X axis signal representing sensed acoustic waves from which the position of a touch relative to said X axis can be determined and a Y axis transducer means for imparting acoustic waves into said substrate for propagation therein relative to an associated Y axis, said Y axis transducer means receiving acoustic waves incident thereto to generate a Y axis signal representing sensed acoustic waves from which the position of a touch relative to said Y axis can be determined, said controller comprising: a signal conditioning circuit responsive to an X axis signal and a Y axis signal simultaneously received by said circuit for rejecting common modes from said signals to provide a conditioned X axis and Y axis signals, said circuit including an amplifier with an adjustable gain; means for detecting the presence or absence of a touch from said conditioned X axis and Y axis signals; means responsive to the detection of a touch for determining the position of said touch relative to said X and Y axes; means operable in the absence of a recognized touch for determining from said conditioned X axis and Y axis signals whether the gain of said amplifier needs adjustment; and means for automatically adjusting the gain of said amplifier if needed.

Claim 14

A controller for an acoustic wave touch panel having a substrate, X axis transducer means for imparting acoustic waves into said substrate for propagation therein relative to an associated X axis, said X axis transducer means receiving acoustic waves incident thereto to generate an X axis signal representing sensed acoustic waves from which the position of a touch relative to said X axis can be determined and a Y axis transducer means for imparting acoustic waves into said substrate for propagation therein relative to an associated Y axis, said Y axis transducer means receiving acoustic waves incident thereto to generate a Y axis signal representing sensed acoustic waves from which the position of a touch relative to said Y axis can be determined, said controller comprising: a signal conditioning circuit responsive to an X axis signal and a Y axis signal simultaneously received by said circuit for rejecting common modes from said signals to provide a conditioned X axis and Y axis signals, said circuit including an amplifier with an adjustable gain; means for detecting the presence or absence of a touch from said conditioned X axis and Y axis signals; means responsive to the detection of a touch for determining the position of said touch relative to said X and Y axes; means operable in the absence of a recognized touch for determining from said conditioned X axis and Y axis signals whether the gain of said amplifier needs adjustment; and means for automatically adjusting the gain of said amplifier if needed.

Claim 15

A controller for an acoustic wave touch panel as recited in claim 12 wherein said touch position determining means includes a low pass filter for filtering said X axis and Y axis signals and a peak detector for detecting the peak of said X axis and Y axis filtered signals.

Claim 16

A controller as recited in claim 12 wherein said peak detector includes differentiator.

Claim 17

A touch position detector for an acoustic touch panel having a substrate and at least one transducer for imparting an acoustic wave into said substrate for propagation along a plurality of paths, each path representing a position along a first axis and for receiving an acoustic wave incident thereto to provide a signal representative of said wave, a touch on said substrate intersecting one of said paths forming a perturbation in said acoustic wave propagating along said path, comprising: means for converting said signal to a plurality of discrete magnitude values each value being associated with a position with respect to said first axis; means for comparing each of a plurality of said magnitude values to a reference value associated with the same position with respect to said first axis as the position of said magnitude value to provide a value representing the difference between said magnitude and reference values; and means for comparing a maximum difference value to a touch threshold to detect a touch on said substrate when said maximum difference is greater than said threshold; and means for determining the position of a touch from a plurality of difference values associated with positions with respect to said first axis within a given range of the first axis position associated with said maximum difference value.

Claim 18

A touch position detector for an acoustic touch panel having a substrate and at least one transducer for imparting an acoustic wave into said substrate for propagation along a plurality of paths, each path representing a position along a first axis and for receiving an acoustic wave incident thereto to provide a signal representative of said wave, a touch on said substrate intersecting one of said paths forming a perturbation in said acoustic wave propagating along said path, comprising: means for converting said signal to a plurality of discrete magnitude values each value being associated with a position with respect to said first axis; means for comparing each of a plurality of said magnitude values to a reference value associated with the same position with respect to said first axis as the position of said magnitude value to provide a value representing the difference between said magnitude and reference values; and means for comparing a maximum difference value to a touch threshold to detect a touch on said substrate when said maximum difference is greater than said threshold; and means for determining the position of a touch from a plurality of difference values associated with positions with respect to said first axis within a given range of the first axis position associated with said maximum difference value.

Claim 19

A touch position detector for an acoustic touch panel as recited in claim 15 wherein said position determining means includes a low pass filter for filtering a plurality of said difference values within a given range of said maximum difference value; and a peak detector for detecting a peak of said filtered difference values, the position associated with said peak value representing the position of a touch relative to said first axis.

Claim 20

A touch position detector for an acoustic touch panel as recited in claim 12 wherein said low pass filter averages said difference values along a plurality of points within a given range of said maximum difference value.

Claim 21

A touch position detector for an acoustic touch panel as recited in claim 12 wherein said peak detector differentiates said filtered difference values.

Claim 22

A touch position detector for an acoustic touch panel as recited in claim 12 wherein said peak detector includes a sum of differences filter.

Claim 23

A touch position detector for an acoustic touch panel as recited in claim 15 including at least one transducer for imparting an acoustic wave into said substrate for propagation along a plurality of paths, each path representing a position along a second axis generally perpendicular to said first axis and for receiving an acoustic wave incident thereto to provide a signal representative thereof; means for converting said signal to a plurality of discrete magnitude values each value corresponding to a position with respect to said second axis; means for comparing each of said magnitude values to a reference value corresponding to the same position with respect to said second axis as the position of said magnitude value to provide a value representing the difference between said magnitude and reference values; and said comparing means comparing a maximum difference value associated with said first and second axes to a touch threshold to detect a touch on said substrate when said maximum values are greater than said threshold.

Claim 24

A touch position detector for an acoustic touch panel as recited in claim 15 including at least one transducer for imparting an acoustic wave into said substrate for propagation along a plurality of paths, each path representing a position with respect to a second axis generally perpendicular to said first axis and for receiving an acoustic wave incident thereto to provide a signal representative thereof; means for converting said signal to a plurality of discrete magnitude values each value corresponding to a position with respect to said second axis; means for comparing each of said magnitude values to a reference value corresponding to the same position with respect to said second axis as the position of said magnitude value to provide a value representing the difference between said magnitude and reference values; and means for determining a value representing the pressure of a touch from the magnitudes of a maximum difference signal associated with said first axis and a maximum difference signal associated with a second axis.

Claim 25

A controller for an acoustic wave touch panel as recited in claim 21 wherein said touch position determining means includes a low pass filter for filtering a plurality of said X axis difference values within said range of said maximum X axis difference value and a plurality of said Y axis difference values within a range of said maximum Y axis difference values to provide respective X axis filtered values and Y axis filtered values; and a peak detector for detecting a peak of said X axis filtered value and a peak of said Y axis filtered value, said X axis peak and Y axis peak representing the position of a touch with respect to said X and Y axes.

Claim 26

A touch position detector for an acoustic touch panel as recited in claim 15 wherein said touch panel includes an active touch area and an inactive touch area, said touch position detector detecting a touch only in said active touch area.

Claim 27

A touch position detector for an acoustic touch panel as recited in claim 23 wherein the size of said active area is variable.

Claim 28

A touch position detector for an acoustic touch panel as recited in claim 23 wherein the position of said active area is variable.

Claim 29

A touch position detector for an acoustic touch panel as recited in claim 15 including a touch position coordinate calculator responsive to said determined touch position for determining a value representative of a coordinate of a touch position relative to an origin position of said axis wherein said origin is variable.

Claim 30

A touch position detector for an acoustic touch panel as recited in claim 15 including means for storing a value representing a first detected touch position; means for comparing a value representing a subsequent detected touch position to said first position to determine whether said positions are within a predetermined distance from each other, said subsequent touch position being recognized as a new touch position only if said subsequent position is at a distance from said first position that is greater than said predetermined distance.

Claim 31

A touch position detector for an acoustic touch panel as recited in claim 27 wherein a touch position determined to be a new position is utilized by said comparing means as said first detected touch position for determining whether the next detected touch position is a new position.

Claim 32

A touch position detector for an acoustic touch panel as recited in claim 15 including means responsive to a predetermined number of detected touches for updating said reference values.

Claim 33

A touch position detector for an acoustic touch panel as recited in claim 15 including means for updating said reference values substantially periodically in the absence of a detected touch.

Claim 34

A touch position detector for an acoustic touch panel as recited in claim 15 wherein said touch threshold is variable.

Claim 35

A touch position detector for an acoustic touch panel having a substrate and at least one transducer for imparting an acoustic wave into said substrate for propagation along a plurality of paths, each path representing a position along a first axis and for receiving an acoustic wave incident thereto to provide a signal representative of said wave, a touch on said substrate intersecting one of said paths forming a perturbation in the acoustic wave propagating along said path comprising: a comparator for comparing said received acoustic wave signal to a reference signal to provide a signal representing the difference therebetween; a software low pass filter for filtering said difference signal to provide a filtered difference signal; and a software peak detector for detecting a peak of said filtered difference signal, said peak representing the position of said touch relative to said axis.

Claim 36

A touch position detector for an acoustic touch panel having a substrate and at least one transducer for imparting an acoustic wave into said substrate for propagation along a plurality of paths, each path representing a position along a first axis and for receiving an acoustic wave incident thereto to provide a signal representative of said wave, a touch on said substrate intersecting one of said paths forming a perturbation in the acoustic wave propagating along said path comprising: a comparator for comparing said received acoustic wave signal to a reference signal to provide a signal representing the difference therebetween; a software low pass filter for filtering said difference signal to provide a filtered difference signal; and a software peak detector for detecting a peak of said filtered difference signal, said peak representing the position of said touch relative to said axis.

Claim 37

A touch position detector for an acoustic touch panel as recited in claim 32 wherein said reference signal represents a received acoustic wave propagating in said substrate with no touch intersecting said paths of propagation.

Claim 38

A touch position detector for an acoustic touch panel as recited in claim 32 including means for comparing said difference signal to a threshold value representing a minimum touch difference, said difference signal being filtered if the magnitude of said difference signal is greater than or equal to said threshold value.

Claim 39

A touch position detector for an acoustic touch panel as recited in claim 34 wherein said threshold value is variable.

Claim 40

A touch position detector for an acoustic touch panel as recited in claim 32 wherein said software low pass filter averages said difference signal along a plurality of points within a given range of a point along said signal representing a maximum difference.

Claim 41

A touch position detector for an acoustic touch panel as recited in claim 32 wherein said software peak detector differentiates said filtered difference signal.

Claim 42

A touch position detector for an acoustic touch panel as recited in claim 32 wherein said software peak detector includes a sum of differences filter.

Claim 43

A touch position detector for an acoustic touch panel as recited in claim 32 including at least one transducer for receiving and providing a signal representing acoustic waves incident thereto that propagate in said substrate along a plurality of paths each representing a position along a second axis, said second axis being generally perpendicular to said first axis and said paths representing said second axis intersecting said paths representing said first axis; and a touch pressure detector for determining the pressure of a touch intersecting a path representing said first axis and a path intersecting said second axis from the magnitude of a maximum difference signal associated with a received acoustic wave propagating along a path representing said first axis and from the magnitude of a maximum difference signal associated with a received acoustic wave propagating along a path representing a position along said second axis.

Claim 44

A touch position detector for an acoustic touch panel as recited in claim 39 wherein said touch pressure detector includes means for averaging said magnitudes of said maximum difference signals associated with said first and second axes.

Claim 45

A touch position detector for an acoustic touch panel as recited in claim 32 wherein said substrate includes an active touch area and an inactive touch area, said touch position detector applying to said software peak detector only signals representing positions within said active touch area.

Claim 46

A touch position detector for an acoustic touch panel as recited in claim 41 wherein the size of said active area is variable.

Claim 47

A touch position detector for an acoustic touch panel as recited in claim 41 wherein the position of said active area is variable.

Claim 48

A touch position detector for an acoustic touch panel as recited in claim 32 including a touch position coordinate calculator responsive to said detected peak for determining a value representative of a coordinate of a touch position relative to an origin position of said axis wherein said origin is variable.

Claim 49

A touch position detector for an acoustic touch panel as recited in claim 32 including means for storing a value representing a first detected touch position; means for comparing a value representing a subsequent detected touch position to said first position to determine whether said positions are within a predetermined distance from each other, said subsequent touch position being recognized as a new touch position only if said subsequent position is at a distance from said first position that is greater than said predetermined distance.

Claim 50

A touch position detector for an acoustic touch panel as recited in claim 7 wherein a touch position determined to be a new position is utilized by said comparing means as said first detected touch position for determining whether the next detected touch position is a new position.

Claim 51

A touch position detector for an acoustic touch panel as recited in claim 1 including means responsive to a predetermined number of detected touches for updating said reference signal.

Claim 52

A touch position detector for an acoustic touch panel as recited in claim 1 including means for updating said reference signal substantially periodically in the absence of a detected touch.

Claim 53

A surface acoustic wave touch panel system comprising: a touch panel substrate; X axis transducer means for imparting surface acoustic waves into said substrate for propagation therein relative to an associated X axis, said X axis transducer means receiving acoustic waves incident thereto to generate an X axis signal representing sensed surface acoustic waves from which the position of a touch relative to said X axis can be determined; Y axis transducer means for imparting surface acoustic waves into said substrate for propagation therein relative to an associated Y axis, said Y axis transducer means receiving surface acoustic waves incident thereto to generate a Y axis signal representing sensed surface acoustic waves from which the position of a touch relative to said Y axis can be determined; means for applying a drive signal to one of said X-axis or Y-axis transducer means to impart a surface acoustic wave in said substrate with respect to the axis associated with the driven transducer, said drive signal having a frequency sufficiently low so as to allow said touch panel substrate to be hermetically sealed; and differential means coupled to said X axis and Y axis transducer means for providing a signal representing the difference between simultaneously received X axis and Y axis signals, said difference signal corresponding to said sensed surface acoustic waves propagating relative to the axis associated with said one driven transducer.

Claim 54

A surface acoustic wave touch panel system comprising: a touch panel substrate; X axis transducer means for imparting surface acoustic waves into said substrate for propagation therein relative to an associated X axis, said X axis transducer means receiving acoustic waves incident thereto to generate an X axis signal representing sensed surface acoustic waves from which the position of a touch relative to said X axis can be determined; Y axis transducer means for imparting surface acoustic waves into said substrate for propagation therein relative to an associated Y axis, said Y axis transducer means receiving surface acoustic waves incident thereto to generate a Y axis signal representing sensed surface acoustic waves from which the position of a touch relative to said Y axis can be determined; means for applying a drive signal to one of said X-axis or Y-axis transducer means to impart a surface acoustic wave in said substrate with respect to the axis associated with the driven transducer, said drive signal having a frequency sufficiently low so as to allow said touch panel substrate to be hermetically sealed; and differential means coupled to said X axis and Y axis transducer means for providing a signal representing the difference between simultaneously received X axis and Y axis signals, said difference signal corresponding to said sensed surface acoustic waves propagating relative to the axis associated with said one driven transducer.

Claim 55

A surface acoustic wave touch panel as recited in claim 49 wherein said frequency is between 1 and 3 Mhz.

Claim 56

A surface acoustic wave touch panel comprising: a touch panel substrate; X axis transducer means for imparting surface acoustic waves into said substrate for propagation therein relative to an associated X axis, said X axis transducer means receiving surface acoustic waves incident thereto to generate an X axis signal representing sensed surface acoustic waves from which the position of a touch relative to said X axis can be determined; Y axis transducer means for imparting surface acoustic waves into said substrate for propagation therein relative to an associated Y axis, said Y axis transducer means receiving surface acoustic waves incident thereto to generate a Y axis signal representing sensed acoustic waves from which the position of a touch relative to said Y axis can be determined, said controller comprising: means for applying a drive signal to one of said X-axis or Y-axis transducer means to impart a surface acoustic wave in said substrate with respect to the axis associated with the driven transducer, said drive signal having a frequency sufficiently low so as to allow said touch panel substrate to be hermetically sealed; a signal conditioning circuit responsive to an X axis signal and a Y axis signal simultaneously received by said circuit for rejecting common modes from said signals to provide conditioned X axis and Y axis signals; means for converting said conditioned X axis signal to a plurality of discrete X axis magnitude values, each value being associated with a position with respect to said X axis, said converting means converting said conditioned Y axis signal to a plurality of discrete Y axis magnitude values, each value being associated with a position with respect to said Y axis; means for comparing each of a plurality of said X axis magnitude values to a reference X axis value associated with the same position with respect to said X axis as the position of said X axis magnitude value to provide an X-axis difference value representing the difference between said compared X axis values, said comparing means comparing each of a plurality of said Y axis magnitude values to a reference Y axis value associated with the same position with respect to said Y axis as the position of said Y axis magnitude value to provide a Y axis difference value representing the difference between said compared Y axis values; and means for determining the position of a touch from a plurality of X axis difference values and from a plurality of Y axis difference values.

Claim 57

A surface acoustic wave touch panel comprising: a touch panel substrate; X axis transducer means for imparting surface acoustic waves into said substrate for propagation therein relative to an associated X axis, said X axis transducer means receiving surface acoustic waves incident thereto to generate an X axis signal representing sensed surface acoustic waves from which the position of a touch relative to said X axis can be determined; Y axis transducer means for imparting surface acoustic waves into said substrate for propagation therein relative to an associated Y axis, said Y axis transducer means receiving surface acoustic waves incident thereto to generate a Y axis signal representing sensed acoustic waves from which the position of a touch relative to said Y axis can be determined, said controller comprising: means for applying a drive signal to one of said X-axis or Y-axis transducer means to impart a surface acoustic wave in said substrate with respect to the axis associated with the driven transducer, said drive signal having a frequency sufficiently low so as to allow said touch panel substrate to be hermetically sealed; a signal conditioning circuit responsive to an X axis signal and a Y axis signal simultaneously received by said circuit for rejecting common modes from said signals to provide conditioned X axis and Y axis signals; means for converting said conditioned X axis signal to a plurality of discrete X axis magnitude values, each value being associated with a position with respect to said X axis, said converting means converting said conditioned Y axis signal to a plurality of discrete Y axis magnitude values, each value being associated with a position with respect to said Y axis; means for comparing each of a plurality of said X axis magnitude values to a reference X axis value associated with the same position with respect to said X axis as the position of said X axis magnitude value to provide an X-axis difference value representing the difference between said compared X axis values, said comparing means comparing each of a plurality of said Y axis magnitude values to a reference Y axis value associated with the same position with respect to said Y axis as the position of said Y axis magnitude value to provide a Y axis difference value representing the difference between said compared Y axis values; and means for determining the position of a touch from a plurality of X axis difference values and from a plurality of Y axis difference values.

Claim 58

A controller for an acoustic wave touch panel as recited in claim 51 wherein said touch position determining means includes a low pass filter for filtering a plurality of said X axis difference values within said range of said maximum X axis difference value and a plurality of said Y axis difference values within a range of said maximum Y axis difference values to provide respective X axis filtered values and Y axis filtered values; and a peak detector for detecting a peak of said X axis filtered values and a peak of said Y axis filtered values, said X axis peak and Y axis peak representing the position of a touch with respect to said X and Y axes.

Claim 59

A controller for an acoustic wave touch panel as recited in claim 51 including a touch pressure detector for detecting the pressure of a touch from said maximum X axis difference value and said maximum Y axis difference value.

Claim 60

A controller for an acoustic wave touch panel as recited in claim 53 wherein said touch pressure detector includes means for averaging said magnitudes of said maximum difference signals associated with said X and Y axes.

Claim 61

A controller for an acoustic wave touch panel as recited in claim 51 wherein said signal conditioning circuit includes an amplifier with an adjustable gain and further including means for automatically adjusting the gain of said amplifier.

Claim 62

A controller for an acoustic wave touch panel as recited in claim 55 wherein said gain adjustment means includes means for comparing a difference value associated with a preselected position with respect to the X axis to a gain reference value associated with said preselected position, said gain adjustment means adjusting said gain if said difference value is not within a given range of said gain reference value.

Claim 63

A controller for an acoustic wave touch panel as recited in claim 56 including means for automatically selecting said preselected position upon an initialization of said touch panel from the position of a maximum X axis difference value determined for an untouch panel.

Claim 64

A controller for an acoustic wave touch panel as recited in claim 56 including means for updating said X axis reference values if said gain is adjusted.

Claim 65

A controller for an acoustic wave touch panel as recited in claim 56 wherein said gain adjustment means includes means for comparing a difference value associated with a preselected position with respect to the Y axis to a gain reference value associated with said preselected position, said gain adjustment means adjusting said gain for said Y axis if said difference value is not within a given range of said gain reference value.

Claim 66

A controller for an acoustic wave touch panel as recited in claim 59 including means for automatically selecting said preselected position upon an initialization of said touch panel from the position of a maximum Y axis difference value determined for an untouch panel.

Claim 67

A controller for an acoustic wave touch panel as recited in claim 59 including means for updating said Y axis reference values if said gain is adjusted.

Claim 68

A surface acoustic wave touch panel comprising: a touch panel substrate; X axis transducer means for imparting surface acoustic waves into said substrate for propagation therein relative to an associated X axis, said X axis transducer means receiving surface acoustic waves incident thereto to generate an X axis signal representing sensed surface acoustic waves from which the position of a touch relative to said X axis can be determined; Y axis transducer means for imparting surface acoustic waves into said substrate for propagation therein relative to an associated Y axis, said Y axis transducer means receiving surface acoustic waves incident thereto to generate a Y axis signal representing sensed acoustic waves from which the position of a touch relative to said Y axis can be determined, said controller comprising: means for applying a drive signal to one of said X-axis or Y-axis transducer means to impart a surface acoustic wave in said substrate with respect to the axis associated with the driven transducer, said drive signal having a frequency sufficiently low so as to allow said touch panel substrate to be hermetically sealed; a signal conditioning circuit responsive to an X axis signal and a Y axis signal simultaneously received by said circuit for rejecting common modes from said signals to provide conditioned X axis and Y axis signals; means for detecting the presence or absence of a touch from said conditioned X axis and Y axis signals; means responsive to the detection of a touch for determining the position of said touch relative to said X and Y axes; means operable in the absence of a touch for determining from said conditioned X axis and Y axis signals whether the gain of said amplifier needs adjustment; and means for automatically adjusting the gain of said amplifier if needed.

Claim 69

A surface acoustic wave touch panel comprising: a touch panel substrate; X axis transducer means for imparting surface acoustic waves into said substrate for propagation therein relative to an associated X axis, said X axis transducer means receiving surface acoustic waves incident thereto to generate an X axis signal representing sensed surface acoustic waves from which the position of a touch relative to said X axis can be determined; Y axis transducer means for imparting surface acoustic waves into said substrate for propagation therein relative to an associated Y axis, said Y axis transducer means receiving surface acoustic waves incident thereto to generate a Y axis signal representing sensed acoustic waves from which the position of a touch relative to said Y axis can be determined, said controller comprising: means for applying a drive signal to one of said X-axis or Y-axis transducer means to impart a surface acoustic wave in said substrate with respect to the axis associated with the driven transducer, said drive signal having a frequency sufficiently low so as to allow said touch panel substrate to be hermetically sealed; a signal conditioning circuit responsive to an X axis signal and a Y axis signal simultaneously received by said circuit for rejecting common modes from said signals to provide conditioned X axis and Y axis signals; means for detecting the presence or absence of a touch from said conditioned X axis and Y axis signals; means responsive to the detection of a touch for determining the position of said touch relative to said X and Y axes; means operable in the absence of a touch for determining from said conditioned X axis and Y axis signals whether the gain of said amplifier needs adjustment; and means for automatically adjusting the gain of said amplifier if needed.

Claim 70

A controller for an acoustic wave touch panel as recited in claim 62 wherein said touch position determining means includes a low pass filter for filtering said X axis and Y axis signals and a peak detector for detecting the peak of said X axis and Y axis filtered signals.

Claim 71

A controller as recited in claim 62 wherein said peak detector includes a differentiator.

Claim 72

A surface acoustic wave touch panel as recited in claim 62 wherein said frequency is between 1 and 3 Mhz.