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1. WO1986003320 - METHODE ET DISPOSITIF DE LOCALISATION ELECTRONIQUE D'UN POINT DE TOUCHE

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

CLAIMS

1. An improved touch-sensitive panel for use in a touch-responsive apparatus for determining the location of a current-drawing touch to said touch-sensitive panel, said panel having extending thereon an electrically conductive layer of known spatial impedance properties, the panel comprising
first electrode network means disposed on said panel at a selected location along a first panel axis, said electrode network means having at least three elongated electrode elements spaced-apart along a direction transverse to the first axis, each said electrode element being in electrical
communication with said impedance layer;
a second electrode network means disposed on said panel at a selected location along a second panel axis, said second electrode network means having at least three elongated electrode elements spaced-apart along a direction transverse to the second axis, each said second electrode element being in electrical communication with said impedance layer; and
said first and second electrode network means defining, in part, a touch-effected region of said panel.

2. The touch-sensitive panel of claim 1 further comprising
a third electrode network means
disposed at a selected location along said first axis, said third electrode network means having at least three elongated electrode elements spaced apart along a direction transverse to said first axis, and spaced apart from said first electrode means, each said third electrode element being in electrical communication with said impedance layer;
a fourth electrode network means disposed at a selected location along said second axis spaced apart from said second electrode network means, said fourth electrode means having at least three elongated electrode elements spaced apart along a direction transverse to said second axis, each said fourth electrode element being in electrical
communication with said impedance layer; and
said four electrode network means defining between them said touch-effected region of said panel.

3. An improved touch-sensitive panel for use in a touch-responsive apparatus for determining the location of a current-drawing touch to said panel, said panel having extending thereon an
electrically conductive layer of known spatial impedance properties, the panel further comprising
a first electrode network means
disposed on said panel at a selected location along a first panel axis, said electrode network means having at least three elongated electrode elements disposed along a direction transverse to the first axis, each said electrode element being in electrical
communication with said impedance layer;
a second electrode network means disposed on said panel at a selected location along a second panel axis, said second electrode network means having at least three elongated electrode elements disposed along a direction transverse to the second axis, each said second electrode element being in electrical communication with said impedance layer;
said first and second electrode network means defining, in part, a touch-effected region of said panel; and
interface means in electrical
communication with said resistive layer and with at least three of said electrode elements for effecting substantially linear impedance mapping
characteristics to a touch-effected region of said panel.

4. The touch-sensitive panel of claim 3, further wherein said interface means includes
resistive network means in electrical communication with at least one of said electrode elements and with said resistive layer for providing said electrical communication.

5. The touch-sensitive panel of claim 4 wherein said resistive network means comprises an etched portion of said resistive layer.

6. The touch-sensitive panel of claim 4 wherein said interface means includes passive
electrode means in juxtaposition to said electrode network means and in electrical communication with said resistive layer.

7. The touch-sensitive panel of claim 3 wherein at least one of said first and second
electrode network means includes a plurality of shaped electrode elements disposed on, and in
electrical communication with, said resistive layer.

8. The touch-sensitive panel of claim 1 wherein said first and second electrode network means each include a corner electrode element disposed on the panel in proximity to a region of intersection of axes of said first and second electrode network, and
wherein each said first and second electrode network means further includes an electrode element electrically connected with the respective corner electrode element of said first and second electrode network means through a diode.

9. In a touch-responsive apparatus for determining the location of a current-drawing touch to a panel, said panel having extending thereon an electrically conductive layer of known spatial impedance properties and an electrode configuration in electrical contact with said layer, said apparatus having a source means for generating an electrical signal to establish in said impedance layer a
designated electrical state, said apparatus further having means for determining the effective impedance from an electrode of said electrode configuration, in contact with said layer to a said touch, for mapping the relative location of the touch, the improvement comprising
a first electrode network means
disposed on said panel at a selected location along a first panel axis, said electrode network means having at least three elongated electrode elements disposed along a direction transverse to the first axis, each said electrode element being in electrical
communication with said impedance layer;
a second electrode network means disposed on said panel at a selected location along a second panel axis, said second electrode network means having at least three elongated electrode elements disposed along a direction transverse to the second axis, each said second electrode element being in electrical communication with said impedance layer; said first and second electrode network means defining, in part, a touch-effected region of said panel;
a switching means having at least a first and a second mode and connected for selectively electrically connecting, in the first mode, the source means with at least one of the electrode elements of the first and second electrode network means, and for electrically isolating, in the second mode, at least some of the electrode elements of the first and second electrode network means from said source means; and
interface means in electrical
communication with said impedance layer and with at least three of said electrode elements for effecting substantially linear impedance mapping
characteristics to a touch-effected region of said panel.

10. In the apparatus of claim 9, the improvement further comprising
a third electrode network means
disposed at a selected location along said first axis, said third electrode network means having at least three elongated electrode elements spaced apart along a direction transverse to said first axis, and spaced apart from said first electrode means, each said third electrode element being in electrical communication with said impedance layer;
a fourth electrode network means disposed at a selected location along said second axis spaced apart from said second electrode network means, said fourth electrode means having at least three elongated electrode elements spaced apart along a direction transverse to said second axis, each said fourth electrode element being in electrical
communication with said impedance layer;
said four electrode network means defining between them said touch-effected region of said panel, and
wherein said switching means comprises a diode means in a series electrical connection between said source means and at least three said electrode elements, the diode means having one diode element for each connected electrode element, and said diode elements have a circuit configuration for applying the same potential to selectively one of the first and third, or second and fourth, electrode network means.

11. In the apparatus of claim 10, the improvement wherein said switching means further comprises resistive means in a series electrical connection between at least one said electrode element and said source means for limiting electric charge build-up on said impedance layer.

12. In a touch-responsive apparatus for determining the location of a current-drawing touch to a touch-sensitive panel means, said panel means having extended thereon an electrically conductive layer of known spatial impedance properties and further having an electrode configuration in
electrical contact with the layer, said apparatus having a source means for generating a signal to establish in said impedance layer a designated electrical state, said apparatus further having measuring means for determining the effective
impedance from an electrode, of said electrode configuration, in contact with said layer, to said touch, for mapping the relative location of the touch, the improvement comprising
a first electrode network means
disposed on said panel means at a selected location along a first panel axis, said electrode network means having at least three elongated electrode elements spaced-apart along a direction transverse to the first axis, each said electrode element being in electrical communication with said impedance layer;
a second electrode network means disposed on said panel means at a selected location along a second panel axis, said electrode network means having at least three elongated electrode elements spaced-apart along a direction transverse to the second axis, each said second electrode element being in electrical communication with said impedance layer;
said first and second electrode network means defining, in part, a touch-effected region of said panel means; and electrically connecting, in a first mode, the source means with at least some of the electrode elements of the first and second electrode network means and for electrically isolating in a second mode, at least some of the electrode elements of the first and second electrode network means from said source means.

13. The apparatus of claim 12, wherein said improvement comprises
a third electrode network means
disposed at a selected location along said first axis, said third electrode network means having at least three elongated electrode elements spaced apart along a direction transverse to said first axis, and spaced apart from said first electrode means, each said third electrode element being in electrical communication with said impedance layer;
a fourth electrode network means disposed at a selected location along said second axis spaced apart from said second electrode network means, said fourth electrode means having at least three elongated electrode elements spaced apart along a direction transverse to said second axis, each said fourth electrode element being in electrical
communication with said impedance layer;
said four electrode network means defining between them said touch-effected region of said panel, and
wherein said switching means comprises a diode means in an electrical series connection between and in communication with said source means and at least three said electrode elements, the diode means having one diode element for each connected electrode element, and said diode elements have a circuit configuration for applying the same potential to selectively one of the first and third, or second and fourth, electrode network means.

14. The apparatus of claim 13, wherein said switching means further comprises resistive means in series electrical connection between at least one said electrode element and said source means for limiting electric charge build-up on said impedance layer.

15. The improved touch-sensitive panel for use in a touch-responsive apparatus for determining the location of a current-drawing touch to said touch-sensitive panel, said panel having extending thereon an electrically conductive layer of known spatial impedance properties, said panel comprising
a first electrode network means
disposed on said panel at a selected location along a first panel axis, said electrode network means having at least three elongated electrode elements
spaced-apart along a direction transverse to the first axis, each said electrode element being in electrical communication with said impedance layer; and
a second electrode network means disposed on said panel at a selected location along a second panel axis, said second electrode network means having at least one elongated electrode element along a direction transverse to the second axis, said second electrode element being in electrical
communication with said impedance layer; and said first and second electrode network means defining, in part, a touch-effected region of said panel.

16. The touch-sensitive panel of claim 8 wherein each said corner electrode element has a substantial portion thereof directed at an angle to both of said first and second axes.

17. An improved touch-sensitive panel for use in a touch-responsive apparatus for determining the location of a current-drawing touch to said panel, said panel having extending thereon an
electrically conductive layer of known spatial impedance properties, said panel comprising
a first electrode network means
disposed on said panel at a selected location along a first panel axis, said electrode network means having at least one elongated electrode element along a direction transverse to the first axis, said
electrode element being in electrical communication with said impedance layer;
a second electrode network means disposed on said panel at a selected location along a second panel axis, said second electrode network means having at least one elongated electrode element along a direction transverse to the second axis, said second electrode element being in electrical
communication with said impedance layer;
said first and second electrode network means defining, in part, a touch-effected region of said panel; and interface means in electrical
communication with said resistive layer and with at least one of said electrode elements for effecting substantially linear impedance mapping
characteristics to a touch-effected region of said panel;
said interface means including
resistive network means in electrical communication with at least one of said electrode elements and with said resistive layer for providing said electrical communication; and
said resistive network means including an etched portion of said resistive layer.

18. The touch-sensitive panel of claim 17 wherein siad interface means includes passive
electrode means in juxtaposition to said electrode network means and in electrical communication with said resistive layer.

19. An improved touch-sensitive panel for use in a touch-responsive apparatus for determining the location of a current-drawing touch to said panel, said panel having extending thereon an
electrically conductive layer of known spatial impedance properties, said panel comprising
a first electrode network means
disposed on said panel at a selected location along a first panel axis, said electrode network means having at least one elongated electrode element along a direction transverse to the first axis, said
electrode element being in electrical communication with said impedance layer;

a second electrode network means disposed on said panel at a selected location along a second panel axis, said second electrode network means having at least one elongated electrode element along a direction transverse to the second axis, said second electrode element being in electrical
communication with said impedance layer;
said first and second electrode network means defining, in part, a touch-effected region of said panel;
interface means in electrical
communication with said resistive layer and with at least one of said electrode elements for effecting substantially linear impedance mapping
characteristics to a touch-effected region of said panel; and
wherein at least one of said first and second electrode network means includes a shaped electrode element disposed on, and in electrical communication with, said resistive layer.

20. An improved touch-sensitive panel for use in a touch-responsive apparatus for determining the location of a current-drawing touch to said panel, said panel having extending thereon an
electrically conductive layer of known spatial impedance properties, said panel comprising
a first electrode network means
disposed on said panel at a selected location along a first panel axis, said electrode network means having at least one elongated electrode element along a direction transverse to the first axis, said
electrode element being in electrical communication with said impedance layer;

a second electrode network means
disposed on said panel at a selected location along a second panel axis, said second electrode network means having at least one elongated electrode element along a direction transverse to the second axis, said second electrode element being in electrical
communication with said impedance layer;
said first and second electrode network means defining, in part, a touch-effected region of said panel;
interface means in electrical
communication with said resistive layer and with at least one of said electrode elements for effecting substantially linear impedance mapping
characteristics to a touch-effected region of said panel; and
said first and second electrode network means each including
a corner electrode element
disposed on the panel in proximity to a region of intersection of axes of said first and second
electrode networks, and
a diode means for electrically connecting an electrode element of each said first and second electrode network means with the
respective corner electrode element of said first and second electrode network means.

21. In a touch-responsive apparatus for determining the location of a current-drawing touch to said panel, said panel having extending thereon an electrically conductive layer of known spatial
impedance properties and an electrode configuration in electrical contatct with said layer, said apparatus having a source means for generating a signal to establish in said impedance layer a designated electrical stae, said apparatus further having means for determing the effective impedance from an
electrode, of said electrode configuraton, in contact with said layer to a said touch, for mapping the relative location of the touch, the improvement comprising
a first electrode network means
disposed on said panel at a selected location along a first panel axis, said electrode network means having at least one elongated electrode element along a direction transverse to the first axis, said
electrode element being in electrical communication with said impedance layer;
a second electrode network means disposed on said panel at a selected location along a second panel axis, said second electrode network means having at least one elongated electrode element along a direction transverse to the second axis, said second electrode element being in electrical
communication with said impedance layer;
said first and second electrode network means defining, in part, a touch-effected region of said panel;
a switching means for selectively electrically connecting, in a first mode, the source means with at least one of the electrode elements of the first and second electrode network means and for electrically isolating in a second mode, at least some of the electrode elements of the first and second electrode network means and for electrically isolating in a second mode, at least some of the electrode elements of the first and second electrode network means from said source means;

interface means in electrical
communication with said impedance layer and with at least one of said electrode elements for effecting substantially linear impedance mapping
characteristics to a touch-effected region of said panel; and
said switching means comprises a diode means in a series electrical connection between said source means and at least one said electrode element, said diode means having a circuit configuration for applying the same potential to selectively one of the first and third, or second and fourth, electrode network means.
22. In a method for mapping a touch to an unpatterned and selectively electrically conductive layer having a known conductivity property, wherein the mapping is relative to at least a first
coordinate axis, the improvement comprising the steps of
A. measuring the electrical charge which said layer draws from an electrical signal source in response to the touch,
B. applying at least one of the means for effecting said measurement and said source to said conductive layer at a first position relative to said coordinate, and
C. determining said mapping of the touch relative to said first position in response to said charge measurement.

23. In a method according to claim 22, the further improvement comprising the steps of
A. measuring at a second position relative to said coordinate axis the electrical charge which said layer draws from said electrical signal source in response to the touch, where said first and second positions are selected so that the touch is between said first and second positions, and
B. determining the mapping of the touch in response to an arithmetic ratio function of the measured electrical charges drawn at said first and second positions respectively.

24. In a method according to claim 22 the further improvement comprising the steps of
A. coupling said electrical signal source to said conductive layer at the touch, and
B. providing said first position at the periphery of said layer.

25. In a method according to claim 22 the further improvement comprising the step of
A. coupling said electrical signal source to said conductive layer at the periphery of said layer.

26. In a method according to claim 22 the further improvement comprising the steps of
A. coupling said electrical signal source to said conductive layer at said first
position, and
B. providing said first position at the periphery of said layer.

27. In a method according to claim 22 the further improvement wherein said measuring step includes measuring the incremental charge which said layer draws in the presence of said touch relative to the charge drawn in the absence of said touch.

28. In a method according to claim 22 the further improvement comprising the steps of
A. clamping the electrical potential of the conductive layer to a known level at periodic intervals, and
B. continuing said measurement of charge over plural ones of said periodic intervals.

29. In a method for mapping a touch to an unpatterned and selectively electrically conductive layer having a known conductivity per dimension, wherein the mapping is relative to at least a first coordinate axis, and including applying an electrical measuring signal to said layer, the improvement comprising the steps of
A. measuring the incremental
electrical charge which said layer draws from said measuring signal in the presence of said touch, relative to the charge drawn in the absence of said touch,
B. applying at least one of said measuring signal and the means for effecting said charge measurement to said layer at a first position relative to said first coordinate, and
C. determining said mapping of the touch relative to said first position in response to said charge measurement.

30. In a method according to claim 29 the further improvement comprising the steps of
A. applying a first electrical
measuring signal to said layer at said first position,
B. applying concurrently a second electrical measuring signal to said layer at a second position relative to said first coordinate and spaced from said first position so that the touch being located is between said first and second positions relative to said first coordinate, and
C. selecting said first and second measuring signals to attain a minimal charge drawn by said layer at said first position in the absence of said touch.

31. In a method according to claim 30 the further improvement wherein said first and second measuring signals are substantially identical.

32. In a method according to claim 29 the further improvement comprising the step of applying said measuring signal with a known periodic voltage wave-form.

33. In a method according to claim 30 the further improvement comprising the steps of
A.. measuring the incremental charge which said layer draws, at said second position from said source signal, in the presence of said touch relative to the charge drawn in the absence of said touch, and
B. determining the location of the touch in response to an arithmetic ratio function of said incremental charges measured at said first and said second positions.

34. A method for locating a touch to an unpatterned and selectively electrically conductive layer having a known conductivity per dimension wherein, the location is along a first axis, said method comprising the steps of A. applying to said conductive layer at a first location along said first axis a first measuring signal having a selected voltage,
B. applying a second measuring signal having a selected voltage to said conductive layer at a second location spaced along said first axis from said first location so that the touch is between said first and second locations,
C. measuring at each of said first and second locations the incremental electrical charge which the layer draws from said source signal in the presence of said touch, relative to the charge drawn in the absence of said touch, and
D. determining the relative location of the touch in response to a ratio function of said measures of incremental charge at said first and second locations.

35. A method according to claim 34
comprising the further steps of
A. applying said first and second measuring signals concurrently,
B. selecting said measuring signals to attain minimal electrical charge drawn at each of said first and second positions in the absence of a touch to said conductive layer.

36. A method according to claim 35
comprising the further step of
A. selecting said first and second measuring signals to have identical time-varying periodic voltages having at least a first clamped value.

37. In apparatus for locating a touch to a touch panel having an unpatterned and selectively electrically conductive layer thereon with a known conductivity per dimension property and wherein the location is with reference to at least a first
coordinate axis, said apparatus having the
improvement comprising
A. electrical source means for
applying a known electrical source signal to said conductive layer,
B. means for measuring the incremental charge which said layer draws from said source means in the presence of the touch at at least a first position known with reference to said first
coordinate and relative to which the touch is to be located, relative to the charge which the layer draws from said source means at said first location in the absence of said touch, and
C. means for determining the relative location of the touch in response to the measurement of incremental charge at at least said first position,

38. In apparatus according to claim 37 the further improvement comprising electrical current mirror circuitry connected with said source means and with said conductive layer and with said measuring means for applying said source signal to said
conductive layer and for applying to said measuring means a current signal responsive to the current signal said conductive layer draws from said source means.

AMENDED CLAIMS
[received by the International Bureau on 09 May 1986 (09.05.86);
original claims 1,2 and 15 cancelled; claims 3,7,8,12,17,19,21 and 37 amended;
other claims unchanged (13 pages)]
3. An improved human touch-sensitive panel for use in a touch-responsive apparatus for
determining the location of a current-drawing human touch to said panel, said panel having extending thereon an electrically conductive layer of known spatial impedance properties, the panel further comprising
a first electrode network means
disposed on said panel at a
selected location along a first
panel axis, said electrode network
means having at least three
elongated electrode elements
disposed along a direction
transverse to the first axis, each
said electrode element being in
electrical communication with said
impedance layer and an electrical
voltage source signal;
a second electrode network means
disposed on said panel at a
selected location along a second
panel axis, said second electrode
network means having at least
three elongated electrode elements
disposed along a direction
transverse to the second axis,
each said second electrode element
being in electrical communication
with said impedance layer;
said first and second electrode
network means defining, in part, a
touch-effected region of said
panel; and interface means in electrical communication with said resistive layer and with at least three of said electrode elements for effecting substantially linear impedance mapping characteristics to a touch-effected region of said panel.

7. The touch-sensitive panel of claim 3 wherein at least one of said first and second
electrode network means includes a plurality of shaped electrode elements disposed on, and in
electrical communication with, said resistive layer, said shaped electrode element having at least a non-linear side facing an interior portion of said impedance layer.

8. The touch-sensitive panel of claim 3 wherein said first and second electrode network means each include a corner electrode element disposed on the panel in proximity to a region of intersection of axes of said first and second electrode network, and
wherein each said first and second electrode network means further includes an electrode element electrically connected with the respective corner electrode element of said first and second electrode network means through a diode.

12. In a human touch-responsive apparatus for determining the location of a current-drawing touch to a touch-sensitive panel means, said panel means having extended thereon an electrically
conductive layer of known spatial impedance
properties and further having an electrode
configuration in electrical contact with the layer, said apparatus having a source means for generating a signal to establish in said impedance layer a
designated electrical state, said apparatus further having measuring means for determining the effective impedance from an electrode, of said electrode configuration, in contact with said layer, to said touch, for mapping the relative location of the touch, the improvement comprising
a first electrode network means
disposed on said panel means at a
selected location along a first
panel axis, said electrode network
means having at least three
elongated electrode elements
spaced-apart along a direction
transverse to the first axis, each
said electrode element being in
electrical communication with said
impedance layer;
a second electrode network means
disposed on said panel means at a
selected location along a second
panel axis, said electrode network
means having at least three
elongated electrode elements
spaced-apart along a direction transverse to the second axis, each said second electrode element being in electrical communication with said impedance layer;
said first and second electrode network means defining, in part, a touch-effected region of said panel means; and
electrically connecting, in a first mode, the source means with at least some of the electrode elements of the first and second electrode network means and for electrically isolating in a second mode, at least some of the
electrode elements of the first and second electrode network means from said source means.

17. An improved human touch-sensitive panel for use in a touch-responsive apparatus for
determining the location of a current-drawing human touch to said panel, said panel having extending thereon an electrically conductive layer of known spatial impedance properties, said panel comprising
a first electrode network means
disposed on said panel at a
selected location along a first
panel axis, said electrode network
means having at least one
elongated electrode element along
a direction transverse to the
first axis, said electrode element
being in electrical communication
with said impedance layer and an
electrical voltage source signal; * a second electrode network means
disposed on said panel at a
selected location along a second
panel axis, said second electrode
network means having at least one
elongated electrode element along
a direction transverse to the
second axis, said second electrode
element being in electrical
communication with said impedance
layer and an electrical voltage
source signal;
said first and second electrode
network means defining, in part, a
touch-effected region of said
panel;

.7u
interface means in electrical communication with said resistive layer and with at least one of said electrode elements for effecting substantially linear impedance mapping characteristics to a touch-effected region of said panel;
said interface means including resistive network means in
electrical communication with at least one of said electrode elements and with said resistive layer for providing said
electrical communication; and said resistive network means including an etched portion of said resistive layer.

1 1

19. An improved human touch-sensitive panel for use in a touch-responsive apparatus for
determining the location of a current-drawing touch to said panel, said panel having extending thereon an electrically conductive layer of known spatial impedance properties, said panel comprising
a first electrode network means
disposed on said panel at a
selected location along a first
panel axis, said electrode network
means having at least one
elongated electrode element along
a direction transverse to the
first axis, said electrode element
being in electrical communication
with said impedance layer and with
a source of electrical potential;
a second electrode network means
disposed on said panel at a
selected location along a second
panel axis, said second electrode
network means having at least one
elongated electrode element along
a direction transverse to the
second axis, said second electrode
element being in electrical
communication with said impedance
layer and with a source of
electrical potential;
said first and second electrode
network means defining, in part, a
touch-effected region of said
panel;

interface means in electrical
communication with said resistive
layer and with at least one of
said electrode elements for
effecting substantially linear
impedance mapping characteristics
to a touch-effected region of said
panel;
wherein at least one of said first and second electrode network means includes a shaped electrode element disposed on, and in electrical communication with, said resistive layer, said shaped electrode element having at least a non-linear side facing an interior portion of said impedance layer.

21. In a human touch-responsive apparatus for determining the location of a current-drawing human touch to a panel, said panel having extending thereon an electrically conductive layer of known spatial impedance properties and an electrode
configuration in electrical contact with said layer, said apparatus having a source means for generating a signal to establish in said impedance layer a
designated electrical stae, said apparatus further having means for determine the effective impedance from an electrode, of said electrode configuration, in contact with said layer to a said touch, for mapping the relative location of the touch, the improvement comprising
a first electrode network means
disposed on said panel at a
selected location along a first
panel axis, said electrode network
means having at least one
elongated electrode element along
a direction transverse to the
first axis, said electrode element
being in electrical communication
with said impedance layer and an
electrical voltage source;
a second electrode network means
disposed on said panel at a
selected location along a second
panel axis, said second electrode
network means having at least one
elongated electrode element along
a direction transverse to the

7 .

second axis, said second electrode element being in electrical communication with said impedance layer and an electrical voltage source;
said first and second electrode network means defining, in part, a touch-effected region of said panel;
a switching means for selectively electrically connecting, in a first mode, the source means with at least one of the electrode elements of the first and second electrode network means and for electrically isolating in a second mode, at least some of the
electrode elements of the first and second electrode network means and for electrically isolating in a second mode, at least some of the electrode elements of the first and second electrode network means from said source means;
interface means in electrical communication with said impedance layer and with at least one of said electrode elements for effecting substantially linear impedance mapping characteristics to a touch-effected region of said panel; and said switching means comprises a diode means in a series electrical connection between said source means and at least one said electrode element, said diode means having a circuit
configuration for applying the same potential to selectively one of the first and third, or second and fourth, electrode network means.

37. In apparatus for locating a touch to a touch panel having an unpatterned and selectively electrically conductive layer thereon with a known conductivity per dimension property and wherein the location is with reference to at least a first
coordinate axis, said apparatus having the
improvement comprising
A. electrical source means for
applying a known electrical source signal to said conductive layer,
B. means for measuring an incremental charge which said layer draws over a selected time duration from said source means in the presence of the touch at at least a first position known with reference to said first coordinate and relative to which the touch is to be located, relative to a charge which the layer draws over a selected time duration from said source means at said first
location in the absence of said touch, and
C. means for determining the relative location of the touch in response to the measurement of incremental charge at at least said first position.