Multiple input proximity detector and touchpad system

Abstract

A touchpad is formed of an electrically insulating membrane ( 10 ) with a first series of spaced apart conductors ( 12 ) on a first face of membrane ( 10 ) and a second series of spaced apart conductors ( 14 ) on or proximal thereto, in which there is no electrical contact between the first and second series of conductors ( 12, 14 ) Each conductor in the first and second series of conductors is sensitive to the proximity of a finger to modify the capacitance of the proximate conductor to detect the presence of the finger positioned close to that conductor. A scanning system operative to sample one of the conductors in turn from both the first and second series of conductors ( 12, 14 ) in order to measure and store a capacitance value associated with that respective conductor. The scanning system is operative to maintain all conductors ( 12 -n, 14 -n) at a common potential equal to the potential of the conductor being sampled when the remaining conductors are not actively being sampled by the scanning system.

1. A touchpad comprising an electrically insulating membrane ( 10 ), a first series of spaced apart wires ( 12 ) disposed on a first face of said membrane ( 10 ) and a second series of spaced apart wires ( 14 ) proximal to said membrane, there being no electrical contact between said first and second series of spaced apart wires ( 12 ,  14 ), each wire of said first and second series of spaced apart wires being sensitive to the proximity of a finger to modify the capacitance of the wire in proximity to the finger to detect the presence of the finger positioned in proximity to that wire each wire of said first and second series of wires having a diameter in the range of about 10 microns to about 25 microns. 
     
     
       2. A touchpad comprising an electrically insulating membrane ( 10 ) with a first series of spaced apart conductors ( 12 ) on a first face of said membrane ( 10 ) and a second series of spaced apart conductors ( 14 ) on or proximal thereto, in which there is no electrical contact between said first and second series of conductors ( 12 ,  14 ), each conductor in said first and second series of conductors being sensitive to the proximity of a finger to modify the capacitance of said conductor to detect the presence of the finger positioned close to said conductor, said first and second series of conductors ( 12 ,  14 ) comprising very fine wires, said wires being enamel coated and being in the range of about 10 microns to about 25 microns in diameter and a scanning system operative to sample each one of the conductors in turn from both said first and second series of conductors ( 12 ,  14 ) in order to measure and store a capacitance value associated with that respective conductor, said scanning system being operative to maintain all conductors of said first and second series of conductors ( 12 -n,  14 -n) at a common potential when said conductors are not actively being sampled by said scanning system. 
     
     
       3. A touchpad comprising an electrically insulating membrane ( 10 ) with a first series of spaced apart wires ( 12 ) on a first face of said membrane ( 10 ) and a second series of spaced apart wires ( 14 ) proximal thereto, in which there is no electrical contact between the first and second series of spaced apart wires ( 12 ,  14 ), each wire of said first and second series of spaced apart wires being sensitive to the proximity of a finger to modify the capacitance of the wire to detect the presence of the finger positioned close to that wire, said first and second series of wires having a diameter in the range of about 10 microns to about 25 microns, including a scanning system operative to sample a said one of said wires in turn from both said first and second series of spaced apart wires ( 12 ,  14 ) in order to measure and store a capacitance value associated with that respective wire, wherein the scanning system is operative to maintain all wires ( 12 -n,  14 -n) at a common potential equal to the potential of the wire being sampled when said first and second series of spaced apart wires are not actively being sampled by said scanning system. 
     
     
       4. A touchpad as claimed in  claim 3  in which said scanning system comprises a multiplexer ( 75 ), individual inputs of which are respectively connected to a first end of each respective wire operative to scan each wire said first and second series of spaced apart wires in a defined order such that only one wire is connected to the output of the multiplexer at any time instant and including voltage driving means an input of which is connected to the output of said multiplexer and an output of said voltage driving means is connected to all wires of said first and second series of spaced apart wires ( 12 -n,  14 -n), said voltage driving means thereby maintaining the voltage level on each wire of said first and second series of spaced apart wires ( 12 -n,  14 -n) at a common potential, which common potential is equal to the output voltage potential of the wire being sampled at that time instant. 
     
     
       5. A touchpad as claimed in  claim 4  in which said voltage driving means comprises a unity gain amplifier, the output of which is held at the same voltage as the input, thereby maintaining the voltage level of all wires of said first and second series of spaced apart wires at the same potential. 
     
     
       6. A touchpad as in  claim 4  wherein each of the wires of said first and second series of spaced apart wires is formed from a plurality of electrically connected conducting elements. 
     
     
       7. A touchpad comprising an electrically insulating membrane ( 10 ) with a first series of spaced apart wires ( 12 ) on a first face of said membrane ( 10 ) and a second series of spaced apart wires ( 14 ) proximal thereto, in which there is no electrical contact between said first and second series of spaced apart wires ( 12 ,  14 ), each wire in said first and second series of spaced apart wires being sensitive to the proximity of a finger to modify the capacitance of the wire to detect the presence of the finger positioned close to that wire, each wire of said first and second series of wires having a diameter in the range of about 10 microns to about 25 microns including a scanning system operative to sample a wire in turn from both said first and second series of spaced apart wires ( 12 ,  14 ) in order to measure and store a capacitance value associated with that respective wire, wherein said scanning system is operative to maintain all wires of said first and second series of spaced apart wires ( 12 -n,  14 -n) at a common potential equal to the potential of the wire being sampled when said first and second series of spaced apart wires are not actively being sampled by said scanning system and in which said scanning system comprises a multiplexer ( 75 ), individual inputs of which are respectively connected to a first end of each respective wire operative to scan each wire of said first and second series of spaced apart wires in a defined order such that only one wire is connected to the output of said multiplexer at any time instant and including voltage driving means an input of which is connected to the output of said multiplexer and an output of said voltage driving means is connected to all wires of said first and second series of spaced apart wires ( 12 -n,  14 -n), said voltage driving means thereby maintaining the voltage level on each wire of said first and second series of spaced apart wires ( 12 -n,  14 -n) at a common potential, which common potential is equal to the output voltage potential of the wire being sampled at that time instant. 
     
     
       8. A touchpad useable as a touch screen comprising an electrically insulating membrane ( 10 ) with a first series of spaced apart conductors ( 12 ) on a face of said membrane ( 10 ) and a second series of spaced apart conductors ( 14 ) on or proximal thereto, in which there is no electrical contact between the first and second series of spaced apart conductors ( 12 ,  14 ), each conductor of said first and second series of conductors having a width in the range of about 10 microns to about 25 microns, each conductor in said first and second series of spaced apart conductors being sensitive to the proximity of a finger to modify the capacitance of conductor to detect the presence of the finger positioned close to that conductor characterized in that said first and second series of spaced apart conductors ( 12 ,  14 ) comprise very fine insulation coated electrically conductive conductors. 
     
     
       9. A touchpad as set forth in  claim 8  in which said conductors are enamel coated. 
     
     
       10. touchpad as set forth in  claim 8  wherein said second series of spaced apart conductors ( 14 ) is attached to a further electrically insulating membrane ( 13 ). 
     
     
       11. A touchpad as set forth in  claim 8  wherein said first and second series of spaced apart conductors ( 12 ,  14 ) are arranged to form a plurality of intersections ( 20 ) between said first series of spaced apart conductors and said second series of spaced apart conductors. 
     
     
       12. A touchpad as set forth in  claim 8  in which said touchpad includes an active backplane device. 
     
     
       13. A touchpad as set forth in  claim 8  wherein said second series of spaced apart conductors ( 14 ) is attached to said face of said insulating membrane ( 10 ), said first series of spaced apart conductors ( 12 ) being insulated from said second series of spaced apart conductors ( 14 ) by discrete regions of insulating material ( 13 ′). 
     
     
       14. A touchpad as set forth in  claim 13  wherein said membrane and said insulating material ( 10 ,  13 ′) and said first and second series of spaced apart conductors ( 12 ,  14 ) are laminated between dielectric films ( 50 ). 
     
     
       15. A touchpad as set forth in  claim 8  wherein said second series of spaced apart conductors ( 14 ) are formed on a further face of said membrane ( 10 ). 
     
     
       16. A touchpad as set forth in  claim 15  wherein said second series of spaced apart conductors ( 14 ) is attached to a further electrically insulating membrane ( 13 ). 
     
     
       17. A touchpad as set forth in  claim 16  wherein said membrane and said further membrane including said first and second series of spaced apart conductors ( 12 ,  14 ) are superimposed one above another and a plurality of scanning mechanisms for scanning said first and second series of spaced apart conductors. 
     
     
       18. A touchpad useable as a touch screen comprising an electrically insulating membrane ( 10 ) with a first series of spaced apart conductors ( 12 ) on a face of said membrane ( 10 ) and a second series of spaced apart conductors ( 14 ) on or proximal thereto, said second series of spaced apart conductors ( 14 ) being attached to said face of said insulating membrane ( 10 ), said first series of spaced apart conductors ( 12 ) being insulated from said second series of spaced apart conductors ( 14 ) by discrete regions of insulating material ( 13 ′), the conductors of said first series of spaced apart conductors intersecting at intersections with the conductors of said second series of spaced apart conductors, each of the conductors of said first and second series of spaced apart conductors having a first width ( 22 ) for the larger part of their length, and a second width ( 24 ) being substantially smaller than the first width, which second width is coincidental with each of said intersections ( 20 ), each conductor in said first and second series of spaced apart conductors being sensitive to the proximity of a finger to modify the capacitance of conductor to detect the presence of the finger positioned close to that conductor characterized in that said first and second series of spaced apart conductors ( 12 ,  14 ) comprise very fine insulation coated electrically conductive conductors. 
     
     
       19. A touchpad system including a touchpad comprising an electrically insulating membrane ( 10 ) with a first series of spaced apart conductors ( 12 ) on a face of said membrane ( 10 ) and a second series of spaced apart conductors ( 14 ) on or proximal thereto, in which there is no electrical contact between the first and second series of conductors ( 12 ,  14 ), each conductor of said first and second series of conductors having a width in the range of about 10 microns of about 25 microns, each conductor of said first and second series of spaced apart conductors being sensitive to the proximity of a finger to modify the capacitance of a conductor to detect the presence of the finger positioned close to that conductor characterized in that said first and second series of spaced apart conductors ( 12 ,  14 ) comprise very fine insulation coated electrically conductive conductors including a scanning system operative to sample in turn each conductor from both said first and second series of spaced apart conductors ( 12 ,  14 ) in order to measure and store a capacitance value associated with that respective conductor. 
     
     
       20. A touchpad system as set forth in  claim 19  wherein said scanning system is operative to maintain all conductors ( 12 -n,  14 -n) of said first and second series of spaced apart conductors at a common potential when none of the conductors are being actively sampled by said scanning system. 
     
     
       21. A touchpad system as set forth in  claim 19  wherein said scanning system is capable of determining the position of the finger relative to two or more conductors of said first and second series of spaced apart conductors by means for interpolating the degree of difference in capacitance of the associated conductors. 
     
     
       22. A touchpad system as set forth in  claim 20  wherein the surface area of said touchpad is divided into a plurality of boxes ( 60 ,  61 ), the presence of a finger positioned on any one box being distinguishable by said system from a finger positioned on any other box. 
     
     
       23. A touchpad system including a touchpad useable as a touch screen comprising an electrically insulating membrane ( 10 ) with a first series of spaced apart conductors ( 12 ) on a face of said membrane ( 10 ) and a second series of spaced apart conductors ( 14 ) on or proximal thereto, in which there is no electrical contact between the first and second series of conductors ( 12 ,  14 ), each conductor of said first and second series of spaced apart conductors being sensitive to the proximity of a finger to modify the capacitance of a conductor to detect the presence of the finger positioned close to that conductor characterized in that said first and second series of spaced apart conductors ( 12 ,  14 ) comprise very fine insulation coated electrically conductive conductors, a scanning system operative to sample in turn each conductor from both said first and second series of spaced apart conductors ( 12 ,  14 ) in order to measure and store a capacitance value associated with that respective conductor and an active backplane device and wherein said scanning system is operative to maintain all conductors of said first and second series of spaced apart conductors at the same potential as said active backplane device when the conductors are not being actively sampled by said scanning system. 
     
     
       24. A touchpad useable as a touch screen comprising an electrically insulating membrane ( 10 ) with a first series of spaced apart conductors ( 12 ) on a face of said membrane ( 10 ) and a second series of spaced apart conductors ( 14 ) on or proximal thereto, in which there is no electrical contact between the first and second series of spaced apart conductors ( 12 ,  14 ), each conductor in said first and second series of spaced apart conductors being sensitive to the proximity of a finger to modify the capacitance of conductor to detect the presence of the finger positioned close to that conductor characterized in that said first and second series of spaced apart conductors ( 12 ,  14 ) comprise very fine insulation coated electrically conductive conductors oriented in a zig-zag manner. 
     
     
       25. A multiple input proximity detector including at least one touchpad useable as a touch screen comprising an electrically insulating membrane ( 10 ) with a first series of spaced apart conductors ( 12 ) being disposed on a face of said membrane ( 10 ) and a second series of spaced apart conductors ( 14 ) on or proximal thereto, in which there is no electrical contact between the first and second series of spaced apart conductors ( 12 ,  14 ), each conductor of said first and second series of conductors having a width in the range of about 10 microns to about 25 microns each conductor in said first and second series of spaced apart conductors being sensitive to the proximity of a finger to modify the capacitance of the conductor in proximity to the finger to detect the presence of the finger characterized in that said first and second series of spaced apart conductors ( 12 ,  14 ) comprise very fine insulation coated electrically conductive conductors and in which the juxtaposition of two or more independent capacitance inputs are used to detect the proximity of a finger, such detection only being accepted as valid when all the conductor capacitance inputs indicate a valid detection, where such inputs may be juxtaposed next to a range of other inputs in unique combination such that when any one combination gives a true detection for all its individual inputs, a unique valid detection is determined. 
     
     
       26. A touchpad comprising an electrically insulating membrane, a first series of spaced apart electrical conductors disposed on a first face of said membrane and a second series of spaced apart electrical conductors proximal to said membrane, said first and second series of electrical conductors being insulated from one another, each conductor of said first and second series of electrical conductors having a capacitance that is sensitive to proximity of a finger for detecting a presence thereof, and each conductor of said first and second series of electrical conductors having a width in a range of about  10  microns to about  25  microns. 
     
     
       27. A touchpad comprising an electrically insulating membrane, a first series of spaced apart wires disposed on a first face of said membrane and a second series of spaced apart wires proximal to said membrane, said first and second series of wires being insulated from one another, each wire of said first and second series of wires having a capacitance that is sensitive to proximity of a finger for detecting a presence thereof, and each wire of said first and second series of wires having a width in a range of about  10  microns to about  25  microns. 
     
     
       28. A touchpad as recited in  claim 27 , wherein the width of each of the wires in the first and second series of wires is defined in a plane parallel to the membrane. 
     
     
       29. A touchpad comprising an electrically insulating membrane, a first series of spaced apart electrical conductors disposed on a first face of said membrane and a second series of spaced apart electrical conductors proximal to said membrane, said first and second series of electrical conductors being insulated from one another, each conductor of said first and second series of electrical conductors having a capacitance that is sensitive to proximity of a finger for detecting a presence thereof, and each conductor of said first and second series of electrical conductors having a width in a range of about  10  microns to about  25  microns. 
     
     
       30. A touch pad as recited in  claim 29 , wherein the width of each of the conductors in the first and second series of electrical conductors is defined in a plane parallel to the membrane. 
     
     
       31. A touchpad system comprising:
   an electrically insulating membrane with a first series of spaced apart conductors on a first face of said membrane and a second series of spaced apart conductors on or proximal thereto, said first and second series of conductors being insulated from one another, each conductor in said first and second series of conductors having a capacitance that is sensitive to proximity of a finger for detecting a presence thereof, and said first and second series of conductors comprising conductors having a width in a range of about  10  microns to about  25  microns; and        a scanning system operative to sample each one of the conductors in turn from both said first and second series of conductors in order to measure and store a capacitance value associated with that respective conductor, said scanning system being operative to maintain all conductors of said first and second series of conductors at a common potential when said conductors are not actively being sampled by said scanning system.     
     
     
       32. A touchpad system comprising:
   an electrically insulating membrane with a first series of spaced apart electrical conductors on a first face of said membrane and a second series of spaced apart electrical conductors proximal thereto, the first and second series of conductors being insulated from one another, each conductor of said first and second series of conductors having a capacitance that is sensitive to proximity of a finger for detecting a presence thereof, and said first and second series of conductors having a width in a range of about  10  microns to about  25  microns; and        a scanning system operative to sample a said one of said conductors in turn from both said first and second series of conductors in order to measure and store a capacitance value associated with that respective conductor, wherein the scanning system is operative to maintain all conductors that are not actively being sampled by said scanning system at a common potential equal to the potential of the conductor being sampled.     
     
     
       33. A touchpad system comprising:
   an electrically insulating membrane with a first series of spaced apart electrical conductors on a first face of said membrane and a second series of spaced apart electrical conductors proximal thereto, said first and second series of conductors being insulated from one another, each conductor in said first and second series of conductors having a capacitance that is sensitive to proximity of a finger for detecting a presence thereof, and each conductor of said first and second series of conductors having a width in a range of about  10  microns to about  25  microns; and        a scanning system operative to sample a conductor in turn from both said first and second series of conductors in order to measure and store a capacitance value associated with that respective conductor, wherein said scanning system is operative to maintain all conductors of said first and second series of conductors that are not actively being sampled by said scanning system at a common potential equal to the potential of the conductor being sampled, said scanning system comprising:        a multiplexer, individual inputs of which are respectively connected to a first end of each respective conductor operative to scan each conductor of said first and second series of spaced apart conductors in a defined order such that only one conductor is connected to the output of said multiplexer at any time instant; and        voltage driving means an input of which is connected to the output of said multiplexer and an output of said voltage driving means is connected to all conductors of said first and second series of spaced apart conductors, said voltage driving means thereby maintaining the voltage level on each conductor of said first and second series of spaced apart conductors at a common potential, which common potential is equal to the output voltage potential of the conductor being sampled at that time instant.     
     
     
       34. A touchpad useable as a touch screen comprising an electrically insulating membrane with a first series of spaced apart conductors on a face of said membrane and a second series of spaced apart conductors on or proximal thereto, the first and second series of conductors being insulated from one another, each conductor of said first and second series of conductors having a width in a range of about  10  microns to about  25  microns, and each conductor in said first and second series of conductors having a capacitance that is sensitive to proximity of a finger for detecting a presence thereof, wherein said first and second series of spaced apart conductors comprise insulation coated electrically conductive conductors. 
     
     
       35. A touchpad useable as a touch screen comprising an electrically insulating membrane with a first series of spaced apart conductors on a face of said membrane and a second series of spaced apart conductors on or proximal thereto, said second series of conductors being attached to said face of said insulating membrane, said first series of conductors being insulated from said second series of conductors by discrete regions of insulating material, the conductors of said first series of conductors intersecting at intersections with the conductors of said second series of conductors, each of the conductors of said first and second series of conductors having a first width for the larger part of their length, and a second width being substantially smaller than the first width, which second width is coincidental with each of said intersections, each conductor in said first and second series of conductors having a capacitance that is sensitive to proximity of a finger for detecting a presence thereof, wherein said first and second series of spaced apart conductors comprise fine electrically conductive conductors. 
     
     
       36. A touchpad system comprising:
   a touchpad comprising an electrically insulating membrane with a first series of spaced apart conductors on a face of said membrane and a second series of spaced apart conductors on or proximal thereto, the first and second series of conductors being insulated from one another, each conductor of said first and second series of conductors having a width in a range of about  10  microns to about  25  microns, and each conductor of said first and second series of conductors having a capacitance that is sensitive to proximity of a finger for detecting a presence thereof, wherein said first and second series of spaced apart conductors comprise fine electrically conductive conductors; and        a scanning system operative to sample in turn each conductor from both said first and second series of conductors in order to measure and store a capacitance value associated with that respective conductor.     
     
     
       37. A touchpad system comprising:
   a touchpad useable as a touch screen comprising an electrically insulating membrane with a first series of spaced apart conductors on a face of said membrane and a second series of spaced apart conductors on or proximal thereto, the first and second series of conductors being insulated from one another, each conductor of said first and second series of conductors having a capacitance that is sensitive to proximity of a finger for detecting a presence thereof, wherein said first and second series of conductors comprise fine electrically conductive conductors;        a scanning system operative to sample in turn each conductor from both said first and second series of conductors in order to measure and store a capacitance value associated with that respective conductor; and        an active backplane device;        wherein said scanning system is operative to maintain all conductors of said first and second series of conductors that are not being actively sampled by said scanning system at the same potential as said active backplane device.     
     
     
       38. A touchpad useable as a touch screen comprising an electrically insulating membrane with a first series of spaced apart conductors on a face of said membrane and a second series of spaced apart conductors on or proximal thereto, the first and second series of spaced apart conductors being insulated from one another, each conductor in said first and second series of conductors having a capacitance that is sensitive to proximity of a finger for detecting a presence thereof, wherein said first and second series of spaced apart conductors comprise fine electrically conductive conductors oriented in a zig- zag manner.   
     
     
       39. A touchpad comprising an electrically insulating membrane, a first series of spaced apart conductors disposed proximal a first face of the membrane, a second series of spaced apart conductors disposed between the first series of conductors and the membrane and crossing over the first series of conductors at a plurality of crossover points, and non- continuous insulation disposed between the first and second series of conductors at least at each of the crossover points to prevent electrical contact between the first and second series of conductors, each conductor of the first and second series of conductors having a capacitance that is sensitive to proximity of a finger for detecting a presence thereof.   
     
     
       40. A touchpad as recited in  claim 39 , wherein the non- continuous insulation disposed between the first and second series of conductors comprises isolated regions of insulating material disposed between the first and second series of conductors.   
     
     
       41. A touchpad comprising:
   an electrically insulating membrane;        a first series of spaced apart conductors disposed proximal a first face of the membrane;        a second series of spaced apart conductors disposed between the first series of conductors and the membrane and crossing over the first series of conductors at a plurality of crossover points;        non - continuous insulation disposed between the first and second series of conductors to prevent electrical contact between the first and second series of conductors;        wherein each conductor of the first and second series of conductors has a capacitance that is sensitive to proximity of a finger for detecting a presence thereof; and        wherein conductors of at least one of the first and second series of conductors comprise insulated wires, the non - continuous insulation comprising insulation around the insulated wires.     
     
     
       42. A touchpad comprising an electrically insulating membrane, a first series of spaced apart electrical conductors disposed on a first face of the insulating membrane, and a second series of spaced apart electrical conductors disposed proximal to the membrane, said first and second series of conductors being insulated from one another, each conductor of the first and second series of conductors having a capacitance that is sensitive to proximity of a finger for detecting a presence thereof, the membrane and the first and second series of conductors being encapsulated within a dielectric material. 
     
     
       43. A touchpad as recited in  claim 42 , wherein the dielectric material is a dielectric laminate. 
     
     
       44. A touchpad as recited in  claim 42 , wherein the second series of spaced apart conductors is disposed on a second side of the membrane opposite the first side of the membrane. 
     
     
       45. A touchpad as recited in  claim 42 , wherein the first series of spaced apart conductors is disposed between the membrane and the second series of spaced apart conductors, an electrical insulating layer being disposed between the first and second series of spaced apart conductors. 
     
     
       46. A touchpad as recited in  claim 42 , wherein the first series of spaced apart conductors is disposed between the membrane and the second series of spaced apart conductors, and further comprising discrete portions of insulating material disposed at intersections between conductors of the first and second series of spaced apart conductors. 
     
     
       47. A touchpad as recited in  claim 42  wherein the dielectric laminate is a plastic film. 
     
     
       48. A touchpad useable as a touch screen comprising an electrically insulating membrane with a series of spaced apart conductors on a face of said membrane, each conductor in the series of conductors having a capacitance that is sensitive to proximity of a finger for detecting a presence thereof, the conductors following non- rectilinear paths so as to define respective detection areas on the membrane.   
     
     
       49. A touchpad as recited in  claim 48 , wherein the conductors form an array of discrete pad areas. 
     
     
       50. A touchpad as recited in  claim 48 , wherein the conductors follow enclosed paths so as to define enclosed detection areas. 
     
     
       51. A touchpad as recited in  claim 48 , wherein the detection areas are arranged on the touchpad in a keyboard pattern. 
     
     
       52. A touchpad as recited in  claim 48 , wherein the conductors follow zig- zag paths across the membrane.   
     
     
       53. A touchpad comprising
   an electrically insulating membrane;        a first grid of electrical conductors disposed proximate the membrane, the electrical conductors of the first grid having a capacitance that is sensitive to proximity of a finger for detecting a presence thereof; and        at least a second grid of electrical conductors disposed between the first grid of conductors and the membrane, the electrical conductors of the second grid having a capacitance that is sensitive to proximity of a finger for detecting a presence thereof, a grid spacing of the second grid being different from a grid spacing of the first grid.     
     
     
       54. A touchpad as recited in  claim 53 , wherein the first grid of electrical conductors comprises a first series of spaced apart electrical conductors disposed on a first face of the membrane and a second series of spaced apart electrical conductors disposed proximate the membrane, and the second grid of electrical conductors comprises a third series of spaced apart electrical conductors and a fourth series of spaced apart electrical conductors disposed proximate the membrane. 
     
     
       55. A touchpad as recited in  claim 53 , further comprising a scanning system to determine a position of the finger relative to the touchpad based on a position of the finger relative to the first grid and relative to the second grid. 
     
     
       56. A touchpad as recited in  claim 53 , wherein one of the first and second grids defines duplicate sets of relatively small touch areas forming a large touch area array, and the other first and second grids defines relatively large touch areas so that detection of a finger by at least one of the small touch areas and by one of the large touch areas defines a unique position on the touchpad. 
     
     
       57. A touchpad system comprising:
   a touchpad useable as a touch screen, comprising:        an electrically insulating membrane;        a first series of spaced apart conductors on a face of said membrane; and        a second series of spaced apart conductors on or proximate the membrane;        wherein the first and second series of conductors are insulated from one another, each conductor of said first and second series of conductors has a capacitance that is sensitive to proximity of a finger for detecting a presence thereof, and no conducting backplane is present behind the first and second series of spaced apart conductors; and        a scanning system coupled to the touchpad to sample each conductor from both said first and second series of conductors in order to measure and store a capacitance value associated with that respective conductor, the scanning system maintaining all conductors of said first and second series of conductors at a first potential when the conductors are not being actively sampled by said scanning system, the first potential being related to a signal applied to the conductor being sampled.     
     
     
       58. A touchpad system as recited in  claim 57 , wherein the signal applied to the conductor being sampled oscillates in value by an oscillation magnitude and the first potential oscillates in value by an amount equal to the oscillation magnitude. 
     
     
       59. A touchpad system as recited in  claim 58 , further comprising a non- inverting unity gain amplifier to generate the first potential based on the signal applied to the conductor being sampled.   
     
     
       60. A touchpad as recited in  claim 57 , wherein the conductors have a width in a range of about  10  microns to about  25  microns. 
     
     
       61. A touchpad system comprising:
   a touchpad useable as a touch screen, comprising:        an electrically insulating membrane;        a first series of spaced apart conductors on a face of said membrane; and        a second series of spaced apart conductors on or proximate the membrane; wherein the first and second series of conductors are insulated from one another, each conductor of said first and second series of conductors has a capacitance that is sensitive to proximity of a finger for detecting a presence thereof; and        a conducting backplane disposed behind the first and second series of conductors, at least a portion of the conducting backplane extending in front of the first and second series of conductors; and        a scanning system coupled to the touchpad to sample each conductor from both said first and second series of conductors in order to measure and store a capacitance value associated with that respective conductor, the scanning system maintaining all conductors of said first and second series of conductors and the conducting backplane at a first potential when the conductors are not being actively sampled by said scanning system, the first potential being related to a signal applied to the conductor being sampled.     
     
     
       62. A touchpad system comprising:
   a touchpad useable as a touch screen, comprising:        an electrically insulating membrane;        a first series of spaced apart conductors on a face of said membrane; and        a second series of spaced apart conductors on or proximate the membrane;        wherein the first and second series of conductors are insulated from one another, each conductor of said first and second series of conductors has a capacitance that is sensitive to proximity of a finger for detecting a presence thereof; and        a scanning system coupled to the touchpad to sample each conductor from both said first and second series of conductors in order to measure and store a capacitance value associated with that respective conductor, the scanning system applying a probe signal to the respective conductor at a frequency dependent on the capacitance of the respective conductor and being coupled to apply a first potential to the conductors not being sampled, the first potential being derived from the probe signal applied to the respective conductor.     
     
     
       63. A touchpad system as recited in  claim 62 , further comprising a backplane disposed behind the first and second series of conductors, the scanning system coupled to apply the first potential to the backplane. 
     
     
       64. A touchpad comprising:
   a dielectric medium;        a plurality of conductors disposed in proximity to the dielectric medium throughout a touch sensitive area, each of the conductors being transverse to at least one other of the conductors along respective segments thereof to establish a plurality of pairs of transverse conductive segments; and        a plurality of intervening insulating regions respectively disposed at least between the transverse conductive segments of the pairs;        wherein at least one segment within each pair of transverse conductive segments has an effective width in a range of about  10  microns to about  25  microns.     
     
     
       65. The touchpad of  claim 64  wherein each of the segments having an effective width in a range of about  10  microns to about  25  microns is a region of one of the conductors having a generally constant width in a range of about  10  microns to about  25  microns throughout the touch sensitive area. 
     
     
       66. The touchpad of  claim 64  wherein each of the segments having an effective width in a range of about  10  microns to about  25  microns is a reduced width region of one of the conductors generally having a width greater than about  25  microns throughout the touch sensitive area. 
     
     
       67. The touchpad of  claim 66  wherein the reduced width region is a narrowed region. 
     
     
       68. The touchpad of  claim 66  wherein the reduced width region is a window- containing region.   
     
     
       69. A touchpad comprising:
   a dielectric medium;        a plurality of conductors disposed in proximity to the dielectric medium throughout a touch sensitive area, each of the conductors being transverse to at least one other of the conductors along respective segments thereof to establish a plurality of pairs of transverse conductive segments; and        a plurality of intervening insulating regions respectively disposed at least between the transverse conductive segments of the pairs,        wherein at least one segment within each pair of transverse conductive segments is a reduced width region of one of the conductors.     
     
     
       70. The touchpad of  claim 69  wherein the reduced width region is a narrowed region. 
     
     
       71. The touchpad of  claim 69  wherein the reduced width region is a window- containing region.   
     
     
       72. A touchpad system comprising:
   a surface;        a plurality of conductors, each of the conductors having at least a segment thereof disposed in proximity to the surface for capacitively coupling through the surface to a finger brought into proximity with the segment;        a capacitance - controlled oscillator having a frequency of oscillation that is sensitive to capacitance at an input thereof, and an amplitude of oscillation;        a switch for successively coupling the input of the oscillator to the conductors, wherein when at least one of the conductors is coupled to the input of the oscillator through the switch, at least one of the conductors is uncoupled to the input of the oscillator; and        a source of electric potential having an output for supplying a first potential to the uncoupled conductor or conductors.     
     
     
       73. The touchpad system of  claim 72  wherein the first potential is a ground potential. 
     
     
       74. The touchpad system of  claim 72  wherein the first potential is a common potential. 
     
     
       75. The touchpad system of  claim 72  wherein the source of electric potential has an input coupled to the oscillator, the first potential being related to the frequency and amplitude of oscillation of the oscillator. 
     
     
       76. The touchpad system of  claim 72  wherein:
   the oscillator operationally places a second potential on the coupled conductor or conductors, the second potential having a frequency and amplitude at least in part determined by the capacitance of the coupled conductor or conductors; and        the source of electric potential comprises a unity gain non - inverting amplifier having an input coupled to the oscillator, and an output for providing the first potential at a frequency and amplitude substantially equal to the frequency and amplitude of the second potential.     
     
     
       77. The touchpad system of  claim 72  further comprising a backplane coupled to the output of the source of electric potential, the conductors respectively having front sides facing the surface and back sides opposite the surface, and the backplane extending across the conductors along the back sides thereof. 
     
     
       78. The touchpad system of  claim 77  wherein the backplane further extends along a portion of the front sides of the conductors. 
     
     
       79. The touchpad system of  claim 72  wherein a first set of the conductors extend generally parallel to the surface in a first direction and a second set of the conductors extend generally parallel to the surface in a second direction, each of the conductors of the first set being transverse to the conductors of the second set and insulated therefrom at least where transverse, and each of the conductors of the second set being transverse to the conductors of the first set and insulated therefrom at least where transverse. 
     
     
       80. The touchpad system of  claim 79  wherein:
   the conductors of the first set are generally of a predetermined width relative to the surface, and are generally parallel to one another with intervening spacings much greater than the width thereof; and        the conductors of the second set are generally of a predetermined width relative to the surface, and are generally parallel to one another with intervening spacings much greater than the width thereof.     
     
     
       81. The touchpad system of  claim 72  further comprising:
   a converter coupled to the oscillator for providing digital values indicative of the frequency of oscillation of the oscillator, the digital values being related to the capacitances of the conductors;        a memory coupled to the converter for storing a succession of the digital values for each of the conductors over a plurality of different scans; and        a comparator coupled to the memory for comparing the digital values from the different scans to detect presence and position of a finger in proximity to the touchpad.     
     
     
       82. The touchpad system of  claim 72  wherein the conductors are silver- based conductive ink.   
     
     
       83. The touchpad system of  claim 72  wherein the conductors are conductive elements of a printed circuit board. 
     
     
       84. The touchpad system of  claim 72  wherein the conductors are wires. 
     
     
       85. The touchpad system of  claim 84  wherein at least one of the wires comprises a zigzagged portion. 
     
     
       86. The touchpad system of  claim 72  wherein the conductors are essentially invisible to the naked eye. 
     
     
       87. The touchpad system of  claim 86  wherein the conductors are fine wires. 
     
     
       88. The touchpad system of  claim 87  wherein at least one of the fine wires comprises a zigzagged portion. 
     
     
       89. The touchpad system of  claim 87  wherein the fine wires have a diameter in a range of about  10  microns to about  25  microns. 
     
     
       90. The touchpad system of  claim 87  wherein the fine wires are insulated wires having a diameter in a range of about  10  microns to about  25  microns. 
     
     
       91. The touchpad system of  claim 86  wherein the conductors are indium oxide. 
     
     
       92. A touchpad system comprising:
   a surface;        a first plurality of wires disposed in proximity to the surface;        a second plurality of wires disposed in proximity to the surface;        a capacitance - controlled oscillator having a frequency of oscillation that is sensitive to capacitance at an input thereof; and        a switch for successively coupling the input of the oscillator to the wires;        wherein each of the wires of the first and second plurality of wires is disposed in proximity to the surface for capacitively coupling through the surface to a finger brought into proximity with the wire; and        wherein the first plurality of wires extends generally parallel to the surface in a first direction and the second plurality of wires extends generally parallel to the surface in a second direction, each of the wires in the first plurality of wires being transverse to the wires in the second plurality of wires and insulated therefrom at least where transverse, and each of the wires of the second plurality of wires being transverse to the wires of the first plurality and insulated therefrom at least where transverse.     
     
     
       93. The touchpad system of  claim 92  wherein at least one of the wires comprises a zigzagged portion. 
     
     
       94. The touchpad system of  claim 92  wherein the wires are fine wires that are essentially invisible to the naked eye. 
     
     
       95. The touchpad system of  claim 94  wherein at least one of the fine wires comprises a zigzagged portion. 
     
     
       96. The touchpad system of  claim 94  wherein the fine wires have a diameter in a range of about  10  microns to about  25  microns. 
     
     
       97. The touchpad system of  claim 94  wherein the fine wires are insulated wires having a diameter in a range of about  10  microns to about  25  microns. 
     
     
       98. A touchpad comprising:
   a touch surface;        a plurality of insulation coated wires respectively having at least one zigzagged portion disposed in proximity to the touch surface for allowing a finger in proximity to the zigzagged portion to capacitively couple thereto through the touch surface.     
     
     
       99. The touchpad system of  claim 98  wherein the insulation coated wires are fine insulation coated wires. 
     
     
       100. The touchpad system of  claim 99  wherein the fine insulation coated wires have a diameter in a range of about  10  microns to about  25  microns.