Abstract:
A capacitive touch sensing structure includes: a substrate; a plurality of first electrode groups arranged from a first position towards a second position in a first direction, wherein each of the first electrode groups includes a plurality of first electrodes extended from a third position towards a fourth position in a second direction; a plurality of first conducting wires each having a plurality of contacts respectively coupled to the first electrodes of each of the first electrode groups; a plurality of second electrode groups arranged from the first position towards the second position in the first direction, wherein each of the second electrode groups includes a plurality of second electrodes extended from the fourth position towards the third position in the second direction and respectively staggering with the first electrode groups; and a plurality of second conducting wires each having a plurality of contacts respectively coupled to the electrodes of each of the second electrode groups.

Description:
CROSS REFERENCE TO RELATED PATENT APPLICATIONS 
       [0001]    This patent application claims priority from U.S. Provisional Patent Application No. 61/178,506 filed on May 15, 2009, which is hereby incorporated in its entirety by reference. 
     
    
     TECHNICAL FIELD 
       [0002]    The present disclosure relates to capacitive touch sensing, and more particularly, to a capacitive touch sensing structure and a sensing method thereof. 
       BACKGROUND OF THE PRESENT DISCLOSURE 
       [0003]    As science and technology continue to develop, touch panels are widely applied to various types of electronic apparatuses. In addition to replacing buttons, use of touch panels generally allow electronic apparatuses to also benefit from enlarged display images. 
         [0004]    Common touch panels in general are classified into various types including a resistive type, a capacitive type, an infrared type, and an ultrasonic type, for example. Since a capacitive touch panel includes advantageous features such as being dustproof and scratchproof as well as having a high-resolution, the number of electronic apparatus equipped with a capacitive touch panel has been on the rise. 
         [0005]    A principle of the capacitive touch panel is that a layer of transparent conductive film (e.g., an antimony tin oxide (ATO) layer), placed on a glass substrate, serves as a sensing structure. When a user touches the capacitive touch panel with his finger, close proximity the finger to the touch panel causes variations in capacitance in the sensing structure and coupling capacitance within the sensing structure. The capacitive touch panel determines a location of the touch on the capacitive touch panel according to the capacitance variations in the sensing structure. 
         [0006]      FIG. 1A  shows a prior art capacitive touch sensing structure  1 . The sensing structure  1  includes a substrate  10 , a plurality of first electrodes  11 , a plurality of first conducting wires  12 , a plurality of second electrodes  13  and a plurality of second conducting wires  14 . 
         [0007]    A first direction X points from a first position X 1  to a second position X 2 , and a second direction Y points from a first position Y 1  to a second position Y 2 . 
         [0008]    The first electrodes  11  are arranged in sequence from the first position X 1  towards the second position X 2  in the first direction X of the substrate  10 . Each of the first electrodes  11 , a triangular electrode, has its bottom located at the first position Y 1  in the second direction Y of the substrate  10 , and its top extended towards the second position Y 2 . 
         [0009]    The first conducting wires  12  are respectively electrically connected with the first electrodes  11 . 
         [0010]    The second electrodes  13  are arranged in sequence from the first position X 1  towards the second position X 2  in the first direction X of the substrate  10 . Each of the second electrodes  13 , a triangular electrode, has its bottom located at the second position Y 2  of the substrate  10 , and its top extended towards the first position Y 1 . Further, the second electrodes  13  are staggered with the first electrodes  11  in an electrically isolated manner from each other. 
         [0011]    The second conducting wires  14  are respectively electrically connected to the second electrodes  13 . 
         [0012]    Referring to  FIG. 1B , when a user touches an area A of a capacitive touch panel with his finger, the capacitive touch panel senses a capacitance variance Q 1   a  of a first electrode  11   a  and a capacitance variance Q 2   a  of a second electrode  13   a , and regards a capacitance variance Q 1   b  of a first electrode  11   b  as an error term. A capacitance variance is proportional to a touched area, and a touched area of the first electrode  11   a  touched by the finger of the user, determined by an associated circuit, is greater than an actual touched area due to the error term contributed by the capacitance variance Q 1   b  of the first electrode  11   b . Therefore, a position in the second direction Y, by sensing the capacitance variance in the area A, is determined to be lower than an actual touched position. 
         [0013]    When the user touches an area D of the capacitive touch panel with his finger, the capacitive touch panel senses a capacitance variance Q 1   d  of a first electrode  11   d  and a capacitance variance Q 2   d  of a second electrode  13   d , and regards a capacitance variance Q 2   c  of a second electrode  13   c  as an error term. Therefore, a position in the second direction Y, by sensing the capacitance variance in the area D, is determined to be higher than an actual touched position. 
         [0014]    Therefore, when the user moves the finger in the first direction X on the capacitive touch panel, a position in the second direction Y, sensed by a conventional capacitive touch panel, varies up and down. A reason for such phenomenon lies in changes due to omitted error terms in the process of calculating the second direction Y in the prior art with an error up to 10 mm 
         [0015]    In the prior art, in order to reduce the error and increase accuracy of the capacitive touch panel, more finer first electrodes and second electrodes are provided on the substrate  10 . However, more electrodes need more conducting wires. Corresponding detection circuit is complex and the number of pins connected to electrodes is increased, leading to increased production cost. 
         [0016]    Therefore, without increasing extra conducting wires, a capacitive touch sensing structure and a sensing method thereof capable of more accurately obtaining a touched position on the capacitive touch panel are needed. 
       SUMMARY OF THE PRESENT DISCLOSURE 
       [0017]    A main object of the present disclosure is to provide a capacitive touch sensing structure and a sensing method thereof, so that a touched position is accurately obtained without increasing extra conducting wires. 
         [0018]    In order to achieve the above object, a capacitive touch sensing structure according to the present disclosure comprises a substrate, a plurality of first electrode groups, a plurality of first conducting wires, a plurality of second electrode groups, and a plurality of second conducting wires. 
         [0019]    The substrate comprises a first direction (an X direction) and a second direction (a Y direction)—the first direction extends from a first position X 1  to a second position X 2 , and the second direction extends from a first position Y 1  to a second position Y 2 . 
         [0020]    The electrode groups are arranged in sequence from the first position X 1  towards to the second position X 2  in the first direction X. Each of the electrode groups comprises a plurality of first electrodes, which are triangular electrodes or trapezoid electrodes, and each of the first electors has a bottom located at the first position Y 1  in the second direction X, and a top extended toward the second position Y 2 . 
         [0021]    Each of the first conducting wires comprises a plurality of contacts, which are respectively coupled to the first electrodes of each of the first electrodes groups. 
         [0022]    The second electrodes groups are arranged in sequence from the first position X 1  towards to the second position X 2  in the first direction X. Each of the second electrodes groups comprises a plurality of second electrodes, which are triangular or trapezoid in shape. Each of the second electrodes has a bottom located at the second position Y 2  of the second direction Y of the substrate, and a top extended to the first position Y 1 . Further, the second electrodes are staggered with the plurality of first electrodes in an electrically isolated manner from each other. 
         [0023]    Each of the second conducting wires comprises a plurality of contacts, which are respectively coupled to a plurality of second electrodes of each of the second electrodes groups. 
         [0024]    A sensing method according to the present disclosure comprises touching an area on a substrate of a touch panel by an external object, e.g., a finger touch of a user; sensing a first capacitance variance of a plurality of first electrode groups and a second capacitance variance of a plurality of second electrode groups in the area; estimating a position in a second direction of the area on the substrate according to a ratio between the first capacitance variance of the first electrode groups and the second capacitance variance of the second electrode groups. 
         [0025]    The advantages and spirit related to the present disclosure can be further understood via the following detailed description and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]      FIGS. 1A and 1B  are schematic diagrams of a capacitive touch panel in the prior art. 
           [0027]      FIGS. 2A and 2B  are a capacitive touch sensing structure in accordance with a first embodiment of the present disclosure. 
           [0028]      FIG. 2C  is a flow chart of a sensing method in accordance with an embodiment of the present disclosure. 
           [0029]      FIG. 3  is the capacitive touch sensing structure with a position touched by a finger in accordance with a first embodiment of the present disclosure. 
           [0030]      FIG. 4A  is a capacitive touch sensing structure in accordance with a second embodiment of the present disclosure. 
           [0031]      FIG. 4B  is a flow chart of a sensing method in accordance with an embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0032]      FIG. 2A  shows a capacitive touch sensing structure  2  in accordance with a first embodiment of the present disclosure. The sensing structure  2  comprises a substrate  20 , a plurality of first electrode groups  21 , a plurality of first conducting wires  22 , a plurality of second electrode groups  23 , and a plurality of second conducting wires  24 . 
         [0033]    The substrate  20  can be in shape of a rectangle and comprises a first direction X and a second direction Y. The first direction X directs from a first position X 1  to a second position X 2 , and the second direction Y directs from a first position Y 1  to a second position Y 2 . 
         [0034]    The first electrode groups  21  are arranged in sequence from the first position X 1  towards the second position X 2  in the first direction X. Each of first electrode groups  21  comprises a plurality of first electrodes  211 , which are triangular or trapezoid in shape. Each of the first electrodes has its bottom located at the first position Y 1  of the second direction Y of the substrate  20 , and its top extended towards the second position Y 2 . In this embodiment, each of first electrode groups  21  comprises four first electrodes  211  each having a length as that of a forefinger of an adult person, and each of the first electrodes  211  has its top reaching the second position Y 2  of the second direction Y. 
         [0035]    Each of the first conducting wires  22  comprises a plurality of contacts (four in  FIG. 2A ), which are respectively electrically connected to the plurality of first electrodes  211  of each of the first electrodes groups  21 . 
         [0036]    The second electrode groups  23  are arranged in sequence from a first position X 1  towards the second position X 2  in the first direction X of the substrate  20 . Each of the second electrode groups  23  comprises a plurality of second electrodes  231 , which are triangular or trapezoid in shape. Each of the second electrodes  231  has its bottom located at the second position Y 2  of the second direction Y of the substrate  20 , and its top extended to the first position Y 1 . The second electrode groups  23  are staggered with the first electrode groups  21  in an electrically isolated manner from each other. In this embodiment, each of the second electrode groups  23  comprises four second electrodes  231 . Preferably, each of the second electrodes  231  has a width approximately as that of a forefinger of an adult person, and its top reaching the first position Y 1  of the second direction Y. 
         [0037]    Each of the second conducting wires  24  comprises a plurality of contacts (four in  FIG. 2A ) respectively electrically connected to the plurality of second electrodes  231  of each of the second electrode groups  23 . 
         [0038]    In this embodiment, the capacitive touch sensing structure  2  can be applied to a display panel of an electronic apparatus with touch control and display functions. Preferably, the substrate  20  is a transparent glass substrate, and the foregoing first electrodes  211  and second electrodes  231  are transparent electrodes, e.g., indium tin oxide (ITO) or antimony tin oxide (ATO) film electrodes. The capacitive touch panel can be also a touch panel, which is implemented in a laptop computer but offers no display capability, so that the substrate  20  and the first and second electrodes  211  and  231  need not be transparent. 
         [0039]      FIG. 2C  shows a flow chart of a sensing method in accordance with an embodiment of the present disclosure. The flow chart in  FIG. 2C  is to be described also with reference to  FIG. 2B . 
         [0040]    In Step a, an area A on the substrate  20  of the touch panel is touched by an external object, e.g., a finger of a user. At this point, a coupling capacitor is formed between the user and the touch panel, and an equivalent capacitance of the area A is changed. The change in capacitance, i.e., the capacitance variance, is associated with the finger touched area A having a range covering a first electrode group  21  and a second electrode group  23 . 
         [0041]    In Step b, a capacitance variance ΔQ 1  of the first electrode group  21  and a capacitance variance ΔQ 2  of the second electrode group  23  in the area A are sensed. 
         [0042]    In Step c, according to a ratio between the capacitance variance ΔQ 1  of the first electrode group  21  and the capacitance variance ΔQ 2  of the second electrode group  23 , a position (Y′) of the area A in the second direction of the substrate  20  is estimated. 
         [0043]    A position (X′) of the area A in the first direction X of the substrate  20  is obtained according to positions of the first electrode groups  21  and the second electrode groups  23  in the first direction X where the change of capacitance occurs. 
         [0044]    In Step c, the capacitance variance ΔQ 1  is a sum of all capacitance variances of the first electrodes  211  of the first electrode group  21 , and the capacitance variance ΔQ 2  is a sum of all capacitance variances of the second electrodes  231  of the second electrode group  23 . 
         [0045]    However, the range of the finger touched area A on the substrate  20  may simultaneously cover two first electrode groups  21  and two second electrode groups  23 . The sensing method provided by the present disclosure for the above situation is described below. 
         [0046]    Referring to  FIG. 3 , when a user touches an area A on a capacitive touch panel with his finger, the capacitive touch panel senses a capacitance variance Q 1   a  of a plurality of first electrodes  211   a  of a first electrode group  21   a , and a capacitance variance Q 2   a  of a plurality of second electrodes  231   a  of a second electrode group  23   a , with a capacitance variance Q 1   b  of a first electrode  211   b  being regarded as an error term. 
         [0047]    When the user touches an area D on the capacitive touch panel with his finger, the capacitive touch panel senses a capacitance variance Q 1   d  of a plurality of first electrodes  211   d  of a first electrode group  21   d , and a capacitance variance Q 2   d  of a plurality of second electrodes  231   d  of a second electrode group  23   d , with a capacitance variance Q 2   c  of a second electrode  231   c  being regarded as an error term. 
         [0048]    In this embodiment, a first electrode group  21  is divided into four smaller sizes of the first electrodes  211 , such that a capacitance variance of each of the first electrodes  211  is relatively smaller. Therefore, the error term is correspondingly reduced, so that an actual position touched by the finger becomes more accurately sensed by the touch panel, i.e., the actual touched position is now closer to the position sensed by the touch panel. When a width of the first electrode group is the same (about a width of a forefinger of an adult person) as that of the first electrode in the prior art, the error term can be controlled within 2 mm, which is much better than the error value of 10 mm in the prior art. Further, production cost is kept under control since the number of conducting wires need not be increased. 
         [0049]      FIG. 4A  shows a capacitive touch sensing structure  3  in accordance with a second embodiment of the present disclosure. The sensing structure  3  comprises a substrate  30 , a plurality of first electrode groups  31 , a plurality of first conducting wires  32 , a plurality of second electrode groups  33 , a plurality of second conducting wires  34 , a third electrode  35 , and a third conducting wire  36 . 
         [0050]    The substrate  30 , e.g., in shape of a rectangle, comprises a first direction X and a second direction Y. The first direction X directs from a first position X 1  to a second position X 2 , and the second direction Y directs from a first position Y 1  to a second position Y 2 . 
         [0051]    The first electrode groups  31  are arranged in sequence from the first position X 1  towards to the second position X 2  in the first direction X. Each of the first electrode groups  31  comprises a plurality of first electrodes  311 , which are triangular or trapezoid in shape. Each of the first electrodes  311  has its bottom located at the first position Y 1 , and its top extended in the second direction Y. In this embodiment, each of the first electrode groups  31  comprising four first electrodes  311  has a width as that of a forefinger of an adult person, and its top reaching a central line of the substrate  30 . Preferably, the substrate  30  can be a glass substrate or a flexible substrate. 
         [0052]    The first conducting wires  32  respectively correspond to the first electrode groups  31 , and each of the first conducting wires  32  comprises a plurality of contacts (four in  FIG. 4A ) respectively electrically connected to the first electrodes  311  of each of the first electrode groups  31 . 
         [0053]    The second electrode groups  33  are arranged in sequence from the first position X 1  to the second position X 2  in the first direction X. Each of the second electrode groups  33  comprises a plurality of second electrodes  331 , which are triangular or trapezoid in shape. Each of the second electrodes  331  has its bottom located at the second position Y 2  in the second direction Y towards to the first position Y 1 , so that the second electrode groups  33  corresponds to the first electrode groups  31 . In this embodiment, each of the second electrode groups  33  comprises four second electrodes  331 , and has a width as that of a forefinger of an adult person. Each of the second electrodes  331  has its top reaching the central line of the substrate  30 , and is electrically isolated from the top of each of the first electrode  311 . 
         [0054]    The second conducting wires  34  respectively correspond to a plurality of second electrode groups  33 , and each of the second conducting wires  34  comprises a plurality of contacts (four in  FIG. 4A ) respectively electrically connected to the second electrodes of each of the second electrode groups  33 . 
         [0055]    The third electrode  35  comprises a first area  351  and a second area  352 , which are triangle or trapezoidal. The first area  351  is staggered with the first electrodes  311  of the first electrode groups  31  in an electrically isolated manner from each other. The second area  352  is staggered with the second electrodes  311  of the second electrode groups  31  in an electrically isolated manner from each other. The third conducting wire  36  comprising a contact is electrically connected to the third electrodes  35 . 
         [0056]    In this embodiment, the capacitive touch panel serving as a display panel of an electronic apparatus combines a touch control capability with an image display capability. Therefore, the substrate  30  is a transparent glass substrate, and the foregoing first electrodes  311 , the second electrodes  331  and the third electrode  35  are transparent electrodes, e.g., ITO or ATO film electrodes. In addition, the capacitive touch panel may be a touch panel without a display capability, of a laptop computer. At this point, the substrate  30 , the first and second electrodes  311  and  331 , and the third electrode  35  need not be transparent materials. 
         [0057]      FIG. 4B  shows a flow chart of a sensing method in accordance with an embodiment of the present disclosure. Also with reference to  FIG. 4A , the sensing method comprises steps below. 
         [0058]    In Step a, an area A of a touch panel is touched by an external object, e.g., a user touches the area A with his finger, such that a coupling capacitance is formed between the user and the touch panel to change an equivalent capacitance of the area A. The change in capacitance, i.e., the capacitance variance, is associated with a touched area of the finger of the user, and the touched area covers at least one first electrode group  31  and the third electrode  35  (e.g., the lower part of a substrate is touched), or at least one second electrode group  33  and the third electrode  35  (e.g., the upper part of the substrate is touched), or at least one first electrode group  31 , at least one second electrode groups  33  and the third electrode  35  (e.g., a central area of the substrate is touched). 
         [0059]    In Step b, a capacitance variance ΔQ 1  of the first electrode group  31  of the area A, a capacitance variance ΔQ 2  of the second electrode group  33 , and a capacitance variance ΔQ 3  of the third electrode  35  are respectively sensed. 
         [0060]    In Step c, a position (Y′) of the area A in a second direction of the substrate is estimated, for example, according to a ratio between the capacitance variance ΔQ 1  of the first electrode group  31  and the capacitance variance ΔQ 3  of the third electrode  35 , and a ratio between the capacitance variance ΔQ 2  of the second electrode group  33  and the capacitance variance ΔQ 3  of the third electrode  35 . 
         [0061]    A position (X′) of the area A in a first direction of the substrate  30  is obtained according to a position in the first direction of the first electrode group  31  or the second electrode group  33  where a change in capacitance occurs. 
         [0062]    While the disclosure has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the disclosure needs not to be limited to the above embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.