Abstract:
The present invention is a touch detection panel that uses capacitance changes between electrodes and changes thereof to determine a position of touch. The touch panel can be used in commercial applications where using a finger, stylus, or other object is the desired method of interface with an electronic system. The touch panel includes conductive electrodes and conductive lines connecting the conductive electrodes. The conductive electrodes themselves can be made of opaque conductive material, substantially transparent conductive material, or transparent conductive material depending on the requirements of an application. The Touch panel is connected to a controller that applies current and/or voltage to the touch panel and senses current and/or voltage from the touch panel to determine either single or multiple touch locations.

Description:
BACKGROUND 
       [0001]    Human-machine interface has long been studied and different methods have been developed to interface with machines. Entering characters on a keyboard is one way of entering information into a machine. Using a mouse device is another method to enter information into a computer device by moving a cursor on a screen and pointing to a certain area to enter information. Further, a combination of a keyboard and a mouse device can be used to enter information into a computer device. However, instead of using a keyboard and a mouse combination, a touch panel can be used. A touch panel may either be placed over a display device or may be embedded on a display device or a mouse pad to enter information to a machine. Touch panels detect the object touching the surface of the touch panel and produces a signal that indicate the position of the touch. There are different touch technologies including resistive, capacitive, projected capacitive, acoustic, force and optical. 
         [0002]    In recent years, the most popular technology is a projective capacitive technology due to its ability to detect multiple touches, meaning if several objects touch the touch panel at different locations, those touch locations of all the objects can be determined either simultaneously or in a very short period of time from each other. 
         [0003]    Multiple touch projective capacitive touch panels detect the change in current or voltage due to change in capacitance when an object touches the touch panel. When a current is applied to an electrode of a capacitive touch panel all the capacitances on those electrodes are charged and this charging takes some time. This affects the speed of the panel. 
         [0004]    Capacitive touch panels usually have electrodes placed on a substrate in two different directions that are substantially perpendicular to each other. For example electrodes on a horizontal axis are placed as multiple rows and electrodes on a vertical axis are placed as multiple columns. A typical structure is shown in  FIG. 1 . Electrodes can be either placed on a single layer or on two separate layers. When a single layer structure is used, electrodes are connected with conductive lines and the conductive lines of different axis are insulated from each other where they cross each other. Manufacturing process of a single layer touch panel, therefore requires adding insulator between the conductive lines of different directions. 
       SUMMARY OF THE INVENTION 
       [0005]    One objective of the invention is to eliminate the need for using insulators between the conductive lines of different direction conductive lines. 
         [0006]    Another object of the invention is to manufacture a touch panel wherein all electrodes are placed on the same layer of a substrate and self capacitance and mutual capacitance between the electrodes and between electrodes and earth are used to determine the location of a touch. 
         [0007]    Another object of the invention is to build a touch panel wherein a plurality of capacitances on a surface are used to determine a single or multiple touch locations. 
         [0008]    Another object of the invention is to provide a touch panel wherein as the size increases, regardless of the touch panel structure, the speed of the touch panel is kept at an acceptable level. 
         [0009]    Another object of the invention is to provide a formula for designing a touch panel wherein proper variables are used to change the touch panel design that is sensitive to touches on its surface. 
         [0010]    Another object of the invention is to provide a touch panel wherein the frequency of the input signal is changed to find the filter characteristics of the touch panel and therefore determining the optimum signal frequency to apply to each electrode line therefore increasing the signal to noise ratio. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0011]      FIG. 1  shows a capacitor with two conductive electrodes panel that uses insulators to insulate conductive lines in different directions 
           [0012]      FIG. 2  shows the electrode set up of the capacitive touch screen 
           [0013]      FIG. 3  shows the electrode layout of the capacitive touch panel 
           [0014]      FIG. 4  shows the top view of the capacitive touch panel 
           [0015]      FIG. 5  shows the bottom view of the capacitive touch panel 
           [0016]      FIG. 6  shows cross section of a panel with single layer 
           [0017]      FIG. 7  shows cross section of a panel with double layers 
           [0018]      FIG. 8  shows one group of electrodes being connected to the controller 
           [0019]      FIG. 9  shows the equivalent circuit of two electrodes with mutual capacitance 
           [0020]      FIG. 10  shows a touch panel with all conductive electrodes and conductive lines placed on the same surface of a substrate 
           [0021]      FIG. 11  shows a touch panel with all conductive electrodes and conductive lines placed on the same surface of a substrate where the driving electrode is divided into smaller electrodes. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0022]      FIG. 1  shows a capacitor  60  wherein the capacitance is formed between conductive electrode  1  and conductive electrode  2 . Conductive line  4  and conductive line  5  carry electrical current to move electrical charges into and from the capacitor  60 . A capacitance is created between conductive electrode  1  and conductive electrode  2  as a result of the structure. The length of conductive electrode  1  and conductive electrode  2 , the distance between conductive electrode  1  and conductive electrode  2 , and the permittivity of the material used to build conductive electrode  1  and conductive electrode  2  determine the amount of the capacitance generated between conductive electrode  1  and conductive electrode  2 . 
         [0023]      FIG. 2  shows an embodiment of the current invention. In  FIG. 2 , conductive electrode  6  is made of a conductive material. The width and the length of conductive electrode  6  are determined based on the resistance of the material used as well as the mutual capacitance desired between conductive electrode  6  and conductive electrodes  8 ,  9 ,  10  and  11 . Conductive electrodes  6 ,  8 ,  9 ,  10 , and  11  can be made of a transparent, a substantially transparent or an opaque conductive material. For example for a conductive transparent material, indium tin oxide can be used. For conductive opaque material, silver, copper, gold, or any other conductive metal can be used. The dimensions of conductive electrode  6  is adjusted to provide a capacitance where signal to noise ratio at the output of the capacitive panel is maximized. Conductive electrodes  8 ,  9 ,  10 , and  11  are made of conductive materials. The dimensions of conductive electrodes  6 ,  8 ,  9 ,  10 , and  11  are adjusted to provide a capacitance between conductive electrode  6  and conductive electrodes  8 ,  9 ,  10 , and  11  such that the signal to noise ratio at the output of each conductive electrode is maximized. Conductive electrode  6  is connected to a controller (not shown) by using conductive line  7  and conductive line  207 . Conductive electrodes  8 ,  9 ,  10 , and  11  are connected to a controller by using conductive lines  12 ,  13 ,  14 , and  15  respectively. 
         [0024]      FIG. 3  shows the top view of a part of a capacitive touch panel. The touch panel is made of multiple conductive electrodes and conductive lines connecting conductive electrodes to a controller. Electrode group  200  includes conductive electrodes  16 ,  18 ,  19 ,  20 ,  21  and  22 . Conductive lines  17  and  207  are used to connect conductive electrode  16  to a controller (not shown). Conductive line  23  connects conductive electrode  18  to a controller. Conductive line  24  connects conductive electrode  19  to a controller. Conductive line  25  connects conductive electrode  20  to a controller. Conductive line  26  connects conductive electrode  21  to a controller. Conductive line  27  connects conductive electrode  22  to a controller. 
         [0025]    Electrode group  201  includes conductive electrodes  28 ,  30 ,  31 ,  32 ,  33 , and  34 . Conductive line  29  and conductive line  209  are used to connect conductive electrode  28  to a controller (not shown). Conductive line  35  connects conductive electrode  30  to a controller. Conductive line  36  connects conductive electrode  31  to a controller. Conductive line  37  connects conductive electrode  32  to a controller. Conductive line  38  connects conductive electrode  33  to a controller. Conductive line  39  connects conductive electrode  34  to a controller. 
         [0026]    Electrode group  203  includes conductive electrodes  66 ,  67 ,  68 ,  69 ,  70 , and  71 . Conductive lines  65  and  265  are used to connect conductive electrode  66  to a controller (not shown). Conductive line  72  connects conductive electrode  67  to a controller. Conductive line  73  connects conductive electrode  68  to a controller. Conductive line  74  connects conductive electrode  69  to a controller. Conductive line  75  connects conductive electrode  70  to a controller. Conductive line  76  connects conductive electrode  71  to a controller. 
         [0027]    A controller in this invention is defined as an electrical circuit that can apply an alternating or a direct current to conductive electrodes  16 ,  28 , and  66  while the controller can sense current from conductive electrodes  18 ,  19 ,  20 ,  21 ,  22 ,  30 ,  31 ,  32 ,  33 ,  34 ,  67 ,  68 ,  69 ,  70 , and  71 . 
         [0028]      FIG. 3  shows only three electrode groups  200 ,  201 , and  203 . The touch panel may include many of these electrode groups depending upon the size of the touch panel. The larger the touch panel, the more number of electrode groups are needed. While  FIG. 3  shows that conductive electrodes  16 ,  28  and  66  are connected to a controller by two wires, a single wire configuration is also possible. For example conductive electrode  16  can be connected to a controller using only one conductive line either conductive line  17  or conductive line  207 . Likewise conductive electrode  28  can be connected to a controller using only one conductive line; either conductive line  29  or conductive line  209 . Conductive electrode  66  can be connected to a controller using only one conductive line either conductive line  65  or conductive line  265 . 
         [0029]    Conductive lines  17 ,  207 ,  29 ,  209 ,  65  and  265  can be made of a transparent, substantially transparent or opaque conductive material. For example for a conductive transparent material, indium tin oxide can be used. For conductive opaque material, silver, copper, gold, or any other conductive material can be used. Conductive electrodes  16 ,  28 , and  66  can be made of a transparent, a substantially transparent or an opaque conductive material. For example for a conductive transparent material, indium tin oxide can be used. For a conductive opaque material, silver, copper, gold, or any other conductive material can be used. The dimensions of conductive electrodes  16  are adjusted to provide a capacitance between conductive electrode  16  and conductive electrodes  18 ,  19 ,  20 ,  21 , and  22  where the signal to noise ratio at the output of the capacitive panel is maximized. The dimensions of conductive electrode  28  are adjusted to provide a capacitance between conductive electrode  28  and conductive electrodes  30 ,  31 ,  32 ,  33 , and  34  where the signal to noise ratio at the output of the capacitive panel is maximized. The dimensions of conductive electrode  66  are adjusted to provide a capacitance between conductive electrode  66  and conductive electrodes  67 ,  68 ,  69 ,  70 , and  71  where the signal to noise ratio at the output of the capacitive panel is maximized. 
         [0030]    The capacitive panel is made of many of these electrode groups generating mutual capacitance between them and multiple self capacitances between each individual conductive electrode and ground. Conductive electrodes  18 ,  19 ,  20 ,  21 , and  22  are made of conductive materials. Conductive materials can be a transparent, a substantially transparent or an opaque conductive material. For example for a conductive transparent material, indium tin oxide can be used. For a conductive opaque material, silver, copper, gold, or any other conductive material can be used. The dimensions of conductive electrodes  18 ,  19 ,  20 ,  21 , and  22  are adjusted to provide capacitances between conductive electrode  16  and conductive electrodes  18 ,  19 ,  20 ,  21 , and  22  wherein signal to noise ratio at the output of each conductive electrodes  18 ,  19 ,  20 ,  21 , and  22  are maximized. Conductive electrodes  18 ,  19 ,  20 ,  21 , and  22  are connected to a controller circuit to determine a touch location by conductive lines  23 ,  24 ,  25 ,  26 , and  27  respectively. Conductive lines  23 ,  24 ,  25 ,  26 , and  27  can be made of a transparent, a substantially transparent or an opaque conductive material. For example for a conductive transparent material, indium tin oxide can be used. For a conductive opaque material, silver, copper, gold, or any other conductive material can be used. 
         [0031]    Conductive electrodes  30 ,  31 ,  32 ,  33 , and  34  are made of conductive materials. Conductive materials can be a transparent, a substantially transparent or an opaque conductive material. For example for a conductive transparent material, indium tin oxide can be used. For a conductive opaque material, silver, copper, gold, or any other conductive material can be used. The dimensions of conductive electrodes  30 ,  31 ,  32 ,  33 , and  34  are adjusted to provide capacitances between conductive electrode  16  and conductive electrodes  30 ,  31 ,  32 ,  33 , and  34  wherein signal to noise ratio at the output of each conductive electrodes  30 ,  31 ,  32 ,  33 , and  34  are maximized. Conductive electrodes  30 ,  31 ,  32 ,  33 , and  34  are connected to a controller by using conductive lines  35 ,  36 ,  37 ,  38 , and  39 . Conductive lines  35 ,  36 ,  37 ,  38 , and  39  can be made of a transparent, a substantially transparent or an opaque conductive material. For example for a conductive transparent material, indium tin oxide can be used. For a conductive opaque material, silver, copper, gold, or any other conductive material can be used. 
         [0032]    Conductive electrodes  67 ,  68 ,  69 ,  70 , and  71  are made of conductive materials. Conductive materials can be a transparent, a substantially transparent or an opaque conductive material. For example for a conductive transparent material, indium tin oxide can be used. For a conductive opaque material, silver, copper, gold, or any other conductive material can be used. The dimensions of conductive electrodes  67 ,  68 ,  69 ,  70 , and  71  are adjusted to provide capacitances between conductive electrode  16  and conductive electrodes  67 ,  68 ,  69 ,  70 , and  71  wherein signal to noise ratio at the output of each conductive electrodes  67 ,  68 ,  69 ,  70 , and  71  are maximized. Conductive electrodes  67 ,  68 ,  69 ,  70 , and  71  are connected to a controller circuit by using conductive lines  72 ,  73 ,  74 ,  75 , and  76 . Conductive lines  72 ,  73 ,  74 ,  75 , and  76  can be made of a transparent, a substantially transparent or an opaque conductive material. For example for a conductive transparent material, indium tin oxide can be used. For a conductive opaque material, silver, copper, gold, or any other conductive material can be used. 
         [0033]    In one embodiment, an alternating current is applied to conductive electrodes  16 ,  28  and  66 . The current to these lines is applied one electrode at a time. For example an alternating current is applied to conductive electrode  16  while no current is applied to conductive electrode  28  and conductive electrode  66 . Due to the structure of the conductive electrodes  16 ,  18 ,  19 ,  20 ,  21 , and  22 , mutual capacitances exist between conductive electrodes  16  and  18 ,  16  and  19 ,  16  and  20 ,  16  and  21  and  16  and  22 . When an alternating current is applied to conductive electrode  16 , multiple capacitive reactances form between conductive electrodes  16  and  18 , conductive electrodes  16  and  19 , conductive electrodes  16  and  20 , conductive electrodes  16  and  21  and conductive electrodes  16  and  22 . The value of the capacitive reactance is determined by the frequency of the alternating current applied to conductive electrode  16  and the geometry of conductive electrode  16  and conductive electrodes  18 ,  19 ,  20 ,  21 , and  22 . The capacitive reactances between conductive electrode  16  and conductive electrodes  18 ,  19 ,  20 ,  21 , and  22  form a path for the alternating current from conductive electrode  16  to conductive electrodes  18 ,  19 ,  20 ,  21 , and  22 . Current flow from conductive electrode  16  to conductive electrode  18  and current flow from conductive electrode  16  to conductive electrode  19  are substantially similar. The differences may arise due to changes in manufacturing process. Likewise, the current flow from conductive electrode  16  to conductive electrode  19  is substantially similar to the current flow from conductive electrode  16  to conductive electrode  20 . The current flow from conductive electrode  16  to conductive electrode  20  is substantially similar to the current flow from conductive electrode  16  to conductive electrode  21 . The current flow from conductive electrode  16  to conductive electrode  21  is substantially similar to the current flow from conductive electrode  16  to conductive electrode  22 . Current flows from conductive line  16  to conductive electrodes  18 ,  19 ,  29 ,  21  and  22  due to the mutual capacitance exists between conductive line  16  and conductive electrodes  18 ,  19 ,  20 ,  21 , and  22 . In this embodiment, there are five conductive electrodes that are smaller than conductive electrode  16 . Conductive electrode  16  is also called driving electrode because a current is applied to conductive electrode  16  and as a result of this current flow, an electrical field is generated. Conductive electrodes  18 ,  19 ,  20 ,  21 , and  22  are also called sensing electrodes because conductive electrodes  18 ,  19 ,  20 ,  21 , and  22  are connected to sensing circuit in the controller by corresponding conductive lines  23 ,  24 ,  25 ,  26 , and  27 . The number of sensing electrodes and corresponding conductive lines can vary as needed for any given application of the touch panel. 
         [0034]    In another embodiment, a current may be applied to conductive electrodes  16 ,  28  and  66  at the same time. When the current is applied to conductive electrodes  16 ,  28  and  66  at the same time, conductive electrodes  18 ,  19 ,  20 ,  21 ,  22 ,  30 ,  31 ,  32 ,  33 ,  34 ,  67 ,  68 ,  69 ,  70 , and  71  are sensed to detect the touch location. If there is no touch, a map of the touch panel is created in controller  70 . This map is a map of voltage distribution or current distribution or capacitance distribution. When there is a touch on the surface of touch panel  45  (in  FIG. 10 ) the map will change and this change will be used to detect the touch point on touch panel  45 . 
         [0035]    Conductive lines  23 ,  24 ,  25 ,  26 , and  27 , are connected to a controller circuit as shown in  FIG. 8 . If no object touches the surface of substrate  45  of  FIG. 10 , the output current or voltage measured at conductive lines  23 ,  24 ,  25 ,  26 , and  27  would be substantially similar to each other. However if an object with capacitance, such as a finger, touches or comes to close proximity of conductive electrodes  16 ,  18 ,  19 ,  20 ,  21 , and  22  then the object or finger will introduce additional capacitance between the touch point and the ground. This phenomenon is shown in  FIG. 9  which is the equivalent circuit showing all the resistances and capacitances in the circuit. For example if a finger touches the area between conductive electrode  16  and conductive electrode  18 , an additional capacitance Ct from the touch point to ground would be introduced therefore changing the total capacitance. This change in capacitance would cause a change in capacitive reactance that would cause a change in the output signal. If only the area between conductive electrode  16  and conductive electrode  18  is touched then it would be detected by measuring the conductive lines  23 ,  24 ,  25 ,  26 , and  27 . While the output of conductive lines  24 ,  25 ,  26 , and  27  would be similar to each other, the output at conductive line  23  would be different than others and this difference would indicate that an object touched between conductive electrode  16  and conductive electrode  18 . The signal from conductive lines  23 ,  24 ,  25 ,  26  and  27  can be measured by using one of the different techniques. One technique is to use a charge counting circuit wherein a reference capacitor is charged to a supply voltage level. After the reference capacitor is charged, sensed capacitor is discharged and then charged by the reference capacitor. Each time the sensed capacitor is charged, it reaches to a different voltage than the previous charge. When the sensed capacitor voltage reaches to a threshold level then the number of charge/discharge cycles is counted and the capacitance is determined based on this charge count. An alternative method of measuring signals from conductive lines  23 ,  24 ,  25 ,  26 , and  27  is to measure voltage. Based on the different voltage measurement, a touch location can be determined. For example if there is a touch between conductive electrodes  16  and  18 , the voltage on line  23  will be different than voltages on conductive lines  24 ,  25 ,  26 , and  27 . Controller  70  to determine that the touch location is between conductive electrode  16  and conductive electrode  18  detects this difference. 
         [0036]    The circuit structure shown in  FIG. 8  can be modeled as a filter circuit. In this circuit there are multiple capacitances between conductive electrode  16  and the ground, between conductive electrode  18  and the ground, between conductive electrode  19  and the ground, between conductive electrode  21  and the ground and between conductive electrode  22  and the ground. There are also mutual capacitances between conductive electrode  16  and conductive electrodes  18 ,  19 ,  20 ,  21 , and  22 . Besides these capacitances, there may be other stray capacitances and inductances in the circuit. All these additional capacitances and inductances would affect the operation of the circuit and therefore would change the filter transfer function of the touch panel. The transfer function here is defined as a curve showing the output voltage of the circuit plotted versus the frequency. Based on the circuit characteristics each electrode group may have a different filter transfer function. Furthermore each conductive electrode pair within each electrode group may have a different filter transfer function. These differences are a result of geometry and material variations during manufacturing. Controller  70  applies a signal to conductive electrode  16  at a certain frequency. For example if the input signal is a square wave signal then the fundamental frequency of the input signal is changed and output of the circuit is measured to determine the filter characteristics. These filter characteristics are used to determine the best driving frequency to obtain a higher signal to noise ratio. 
         [0037]    Under normal operation, controller  70  is connected to many electrode groups forming the touch panel. When there is no touch on the surface of touch panel  45 , a map of the touch panel signals is generated within controller  70 . When there is a touch, the touch location would generate a different signal and the saved map therefore indicating the touch location. This operation is performed in the following manner: A current is applied to conductive electrode  16 , conductive electrode  28  and conductive electrode  66  either in a sequential manner or at the same time. If the current is applied to conductive electrode  16 ,  28  and  66  in a sequential manner, then when the current is applied to one of the conductive electrodes  16 ,  28 , and  66 , all other respective sensing conductive electrodes  18 ,  19 ,  20 ,  21 ,  22 ,  30 ,  31 ,  32 ,  33 ,  34 ,  67 ,  68 ,  69 ,  70 , and  71  are sensed. This way a map of voltages, currents, or capacitance of touch panel is stored in the memory of controller  70 . The same process is repeated over and over. If there is no touch on the panel, the map will be similar to the previous map. If there is a touch, the map will change since new capacitance is introduced. The change in map is used to detect the touch location. 
         [0038]      FIG. 3  further shows other conductive electrodes  28 ,  30 ,  31 ,  32 ,  33 ,  34 ,  66 ,  67 ,  68 ,  69 ,  70 , and  71 . Conductive lines  29  and  65  can be made of a transparent material, a substantially transparent material or an opaque conductive material. For example for a conductive transparent material, indium tin oxide can be used. For conductive opaque material, silver, copper, gold, or any other conductive material can be used. Conductive electrodes  30 ,  31 ,  32 ,  33 ,  34 ,  67 ,  68 ,  69 ,  70 , and  71  can be made of a transparent, a substantially transparent or an opaque conductive material. For example for a conductive transparent material, indium tin oxide can be used. For a conductive opaque material, silver, copper, gold, or any other conductive material can be used. The dimensions of capacitive electrodes  29  and  65  are adjusted to provide a capacitance between conductive electrode  29  and conductive electrodes  30 ,  31 ,  32 ,  33 , and  34  and between conductive electrode  66  and conductive electrodes  67 ,  68 ,  69 ,  70 , and  71  The capacitive panel is made of many of these conductive electrodes generating mutual capacitance between them and multiple self capacitance between each individual conductive electrode and ground. Conductive electrodes  30 ,  31 ,  32 ,  33 ,  34 ,  67 ,  68 ,  69 ,  70 , and  71  are made of conductive materials. Conductive materials can be a transparent, a substantially transparent or an opaque conductive material. For example for a conductive transparent material, indium tin oxide can be used. For a conductive opaque material, silver, copper, gold, or any other conductive material can be used. The dimensions of conductive electrodes  30 ,  31 ,  32 ,  33 ,  34 ,  67 ,  68 ,  69 ,  70 , and  71  are adjusted to provide capacitances between conductive electrode  28  and conductive electrodes  30 ,  31 ,  32 ,  33 , and  34  and between conductive electrodes  66  and  67 ,  68 ,  69 ,  70  and  71  wherein signal to noise ratio at the output of each conductive electrodes  30 ,  31 ,  32 ,  33 ,  34 ,  67 ,  68 ,  69 ,  70 , and  71  are maximized. Conductive electrodes  30 ,  31 ,  32 ,  33 ,  34 ,  67 ,  68 ,  69 ,  70 , and  71  are connected to a controller circuit to determine a touch location. These connections to the controller circuit is accomplished by using conductive lines  35 ,  36 ,  37 ,  38 ,  39 ,  72 ,  73 ,  74 ,  75 , and  76 . Conductive lines  35 ,  36 ,  37 ,  38 ,  39 ,  72 ,  73 ,  74 ,  75 , and  76  can be made of a transparent, a substantially transparent or an opaque conductive material. For example for a conductive transparent material, indium tin oxide can be used. For a conductive opaque material, silver, copper, gold, or any other conductive material can be used. 
         [0039]    During the operation of the touch panel, a current is applied to conductive line  29 . This current flows through conductive line  29  and reaches conductive electrode  28 . Due to the structure of the conductive electrodes  28 ,  30 ,  31 ,  32 ,  33 , and  34 , mutual capacitances exist between conductive electrodes  28  and  30 ,  28  and  31 ,  28  and  32 ,  28  and  33  and  28  and  34 . When an alternating current is applied to capacitive electrode  28 , multiple capacitive reactance&#39;s form between conductive electrodes  28  and  30 , the capacitance between conductive electrodes  28  and  31 , the capacitance between conductive electrodes  28  and  32 , the capacitance between conductive electrodes  28  and  33  and the capacitance between conductive electrodes  28  and  34 . The value of the capacitive reactance is determined by the frequency of the alternating current applied to conductive electrode  28  and the geometry of conductive electrode  28  and conductive electrodes  30 ,  31 ,  32 ,  33 , and  34 . The capacitive reactance&#39;s between conductive electrodes  28  and conductive electrodes  30 ,  31 ,  32 ,  33 , and  34  forms a path for the alternating current from conductive electrode  28  and conductive electrodes  30 ,  31 ,  32 ,  33 , and  34 . Current flows from conductive electrode  28  to conductive electrode  30  and current flows from conductive electrode  28  to conductive electrode  31  are substantially similar. Likewise, the current flow from conductive electrode  28  to conductive electrode  31  is substantially similar to the current flow from conductive electrode  28  to conductive electrode  32 . The current flow from conductive electrode  28  to conductive electrode  32  is substantially similar to the current flow from conductive electrode  28  to conductive electrode  33 . The current flow from conductive electrode  28  to conductive electrode  33  is substantially similar to the current flow from conductive electrode  28  to conductive electrode  34 . Current flows from conductive electrode  28  to conductive electrodes  30 ,  31 ,  32 ,  33 , and  34  due to the mutual capacitance exists between conductive electrode  28  and conductive electrodes  30 ,  31 ,  32 ,  33 , and  34 . In this embodiment, there are five conductive electrodes that are smaller than conductive electrode  28 . Conductive electrode  28  is also called driving electrode because a current is applied to conductive electrode  28 . Conductive electrodes  30 ,  31 ,  32 ,  33 , and  34  are called sensing electrodes because conductive electrodes  30 ,  31 ,  32 ,  33 , and  34  are connected to a sensing circuit in the controller by corresponding conductive lines  35 ,  36 ,  37 ,  38 , and  39 . A touch panel may have many of these conductive electrode pairs each pair corresponding to a touch location. Although the number of sensing electrodes in this embodiment is five, the number of sensing electrodes may change based on the size of the touch panel. Likewise while a single driving electrode is used for each electrode group, there may be more than one driving electrode(s). As a matter of fact there may be five driving electrodes, with one driving electrode corresponding to each sensing electrode. Further the number of driving electrodes (and corresponding sensing electrodes) can be more than five, and may increase up to any number. Further still, the ratio of driving electrodes to corresponding sensing electrodes can vary. 
         [0040]    Conductive lines  35 ,  36 ,  37 ,  38 , and  39  are connected to a controller circuit as shown in  FIG. 8 . If there were no object touching the surface of substrate  45 , the output current or voltage measured at conductive lines  35 ,  36 ,  37 ,  38 , and  39  would be substantially similar to each other. However if an object with capacitance, such as a finger, touches or comes to close proximity of conductive electrodes  28 ,  30 ,  31 ,  32 ,  33 , and  34  then the object or finger will introduce additional capacitance between the touch point and ground. This phenomenon is shown in  FIG. 9  which is the equivalent circuit showing all the resistances and capacitances in the circuit. For example if a finger touches the area between conductive electrode  28  and conductive electrode  30 , an additional capacitance Ct from the touch point to ground would be introduced therefore changing the total capacitance. This change in capacitance would cause a change in capacitive reactance, which would cause a change in the output signal. If only the area between conductive electrode  28  and conductive electrode  30  is touched then it would easily be detected by measuring the conductive lines  35 ,  36 ,  37 ,  38 , and  39 . While the output of conductive lines  36 ,  37 ,  38 , and  39  would be similar to each other, the output at conductive line  35  would be different than others and this difference would indicate that an object touched between conductive electrode  28  and conductive electrode  30 . 
         [0041]      FIG. 4  shows another embodiment. In this embodiment, conductive lines are placed on two different surfaces of substrate  45 .  FIG. 4  shows the top view of a dual layer structure. Conductive electrodes  16 ,  18 ,  19 ,  20 ,  21 , and  22  and other conductive electrodes are placed on the top surface of substrate  45 . Conductive lines  23 ,  24 ,  25 ,  26 , and  27  are placed at the bottom layer of substrate  45  as shown in  FIG. 5 . Electrical connections from conductive electrodes  16 ,  18 ,  19 ,  20 ,  21 , and  22  at the top surface to conductive lines  23 ,  24 ,  25 ,  26 , and  27  at the bottom surface are provided by via holes  300 - 317 . Via holes  300 - 317  are filled with conductive material and make contact to conductive electrodes at the top surface and conductive lines at the bottom surface.  FIG. 6  shows a cross sectional view of  FIG. 4  wherein conductive electrodes are placed on the top surface of substrate  45  and conductive lines  646 ,  647 ,  648 ,  649  on the bottom surface.  FIG. 7  shows a cross sectional view of  FIG. 4  and  FIG. 5  wherein sensing conductive electrodes  751 ,  752 ,  753 ,  754  are shown at the top surface and driving electrode  755  at the bottom surface of substrate  45 .  FIG. 7  is an alternate embodiment showing a dual layer structure. 
         [0042]      FIG. 10  shows an embodiment where all conductive electrodes are placed on the same surface of substrate  45 . In this embodiment, substrate  45  can be made of an opaque material or a transparent material or a substantially transparent material. If substrate  45  is made of a transparent or a substantially transparent material, it can be made of a glass or plastic. Conductive electrodes are placed on the same surface of substrate  45 ; the surface can be either the top surface of substrate  45  or the bottom surface of substrate  45 . For simplicity the left column of conductive electrodes and corresponding conductive lines are numbered. Other conductive electrodes in different columns work in a similar manner. Conductive electrode  100  is the left most conductive electrode which is connected to controller  70  by conductive line  109 . Conductive electrode has longer length than conductive electrodes  101 ,  102 ,  103 ,  104 ,  105 ,  106 ,  107  and  108 . The number of conductive electrodes may change based on the design needs. While conductive electrode  100  in this embodiment has a longer length than conductive electrodes  101 ,  102 ,  103 ,  104 ,  105 ,  106 ,  107  and  108 , it is easily possible to have a conductive electrode structure wherein conductive electrode  100  is divided into several conductive electrodes in smaller sizes. As a matter of fact this arrangement is shown in  FIG. 11 . Furthermore while a rectangular shape is used for conductive electrodes in this embodiment, the shape of conductive electrode  100  and conductive electrodes  101 ,  102 ,  103 ,  104 ,  105 ,  106 ,  107  and  108  and all other conductive electrodes used on the surface of substrate  45  can have different shapes, for example diamond, hexagonal, square, circle or any other shape. Conductive electrodes  101 ,  102 ,  103 ,  104 ,  105 ,  106 ,  107  and  108  are connected to controller  70  by conductive lines  110 ,  111 ,  112 ,  113 ,  114 ,  115 ,  116 ,  117 . These conductive lines can be made of a transparent material, an opaque material, or a substantially transparent material. For example for a substantially transparent material indium tin oxide, indium zinc oxide, antominum tin oxide, aluminum zinc oxide, or any other suitable substantially transparent material can be used. For opaque material, metal such as silver, gold, copper or any other conductive metal can be used. Controller  70  has an electronic circuit to generate alternating current and sense signal from conductive electrodes. The sensing can be either in terms of sensing changes in current or voltage. Controller  70  can be built to have the capability of both current and voltage sensing. When drive/sense method of detecting a touch location is used, mutual capacitances between conductive electrode  100  and conductive electrodes  101 ,  102 ,  103 ,  104 ,  105 ,  106 ,  107  and  108  are used. In this case, controller  70  applies alternating current on conductive line  109 . This alternating current reaches conductive electrode  100  since conductive line  109  is connected to conductive electrode  100 . Part of the current flowing through conductive electrode  100  flows to neighboring conductive electrodes due to the mutual capacitance between conductive electrode  100  and conductive electrodes  101 ,  102 ,  103 ,  104 ,  105 ,  106 ,  107 ,  108 . Since the distance between conductive electrode  100  and conductive electrodes  101 ,  102 ,  103 ,  104 ,  105 ,  106 ,  107 ,  108  are substantially similar, the leakage current from conductive electrode  100  to conductive electrodes  101 ,  102 ,  103 ,  104 ,  105 ,  106 ,  107  and  108  will be substantially similar. However even if the currents flowing to conductive electrodes  101 ,  102 ,  103 ,  104 ,  105 ,  106 ,  107  and  108  are not similar due to material and design differences, controller  70  measures these currents and places in a storage unit. This way controller  70  has a map of the surface of substrate  45 . The process is repeated for each driving conductive electrode and all the sensing conductive electrodes are measured. When all driving conductive electrodes are applied current in a sequential manner and all sensing electrodes are sensed when one driving electrode is applied current, when the process is completed, a complete map of the surface of the substrate is established within controller  70 . From that point on if an object with a capacitance touches the surface of substrate  45  or comes close to the surface of substrate  45  such that the object introduces capacitance, an additional capacitance between the touch location and ground will be introduced to the circuit. As controller  70  keeps driving the driving conductive electrodes and sensing the sensing conductive electrodes, the change in capacitance will be detected by controller  70  by detecting the change in current or voltage. The location where the change in current or voltage occurs is the location of touch. Controller  70  is able to detect multiple current or voltage changes on the surface which means multiple touch locations can be detected at the same time or at times close to each other. 
         [0043]    The size of conductive electrodes may vary. The detailed view of conductive electrodes and conductive lines is shown in  FIG. 8 . Multiple conductive electrodes and conductive lines are used in  FIG. 10  to form touch panel  80 . Conductive electrodes and conductive lines can be made of a transparent material, an opaque material or a substantially transparent material or any combination thereof. Conductive lines carry electric current between controller  70  and conductive electrodes. In this embodiment, the surface is divided as an upper part and lower part. For the upper part, conductive lines connecting to conductive electrodes are routed towards the upper end of substrate  45 . For the lower part, conductive lines connecting controller to conductive electrodes are routed towards the bottom end of substrate  45 . This way, there is enough space between adjacent conductive electrodes to route conductive lines. In an alternative arrangement, all the conductive lines connecting to conductive electrodes can be routed either to the upper end or to the lower end of substrate  45 . In yet another alternative arrangement, conductive lines can be routed to the left or to the right end of substrate  45 . In another embodiment conductive lines may be routed randomly, some being routed to top part of substrate  45 , some being routed to the bottom part of substrate  45 , some being routed to the right part of substrate  45  and some being routed to the left part of substrate  45 . 
         [0044]      FIG. 11  shows another embodiment of the invention. In this embodiment, there are multiple conductive electrodes  500  that are used as driving electrodes on substrate  45 . Conductive electrodes  500  are connected to each other by conductive wires. While it is shown that conductive electrodes  500  are connected to each other, it is also possible to connect each conductive electrode  500  to controller  70  individually. Conductive electrodes  501  through  508  are sensing electrodes and are individually connected to controller  70 . While conductive lines connecting conductive electrodes  501  through  508  are shown in a certain way in  FIG. 11 , any wiring configuration can be used. For example conductive wires can be routed between driving electrodes and sensing electrodes. Additionally the conductive wires and conductive lines can be built such that once they reach the edge of the substrate they connect to the controller via a flexible printed circuit. 
         [0045]    During the operation of the touch panel, each driving line  550  either driven by controller  70  individually in a sequence then sense all sense electrodes or driving lines may be driven simultaneously and sensing lines are sensed. In yet another embodiment, the odd numbered driving lines are driven by controller  70  while all sense lines are sensed and then even number of driving lines are driven by controller  70  and all sense lines are sensed. For example at the first instance 1 st , 3 rd , 5 th , 7 th  driving lines are driven while all sense lines are sensed. Then 2 nd , 4 th , 6 th , and 8 th  driving lines are driven while all sense lines are sensed. Alternatively, every 3 rd  or 4 th  or n th  lines can be driven at the same time while the two nearest columns of sensing electrodes are sensed. Regardless of how the driving lines are driven, and how the sensing electrodes are sensed, a map of the touch panel showing the distribution of voltages, currents or capacitances is made during sensing the touch panel and stored in controller  70 . If there is a touch on the touch panel, the capacitance at the touch point will change and this change will alter the new map. When the new map is compared to the map in storage, a touch point will be detected where the difference in the map is.