Abstract:
An electrostatic capacitive coupling type touch panel including an Input region having four sides, a peripheral region around the input region, terminals formed in the peripheral region along a first side of the input region, wirings formed in the peripheral region along second, third and fourth sides of the input region, and the input region having X and Y electrodes crossing. The wirings are connected between corresponding X or Y electrodes and wiring terminals plurality of terminals. A dummy wiring, which is not connected to any of the X electrodes or Y electrodes, is provided outside the wiring formed in a farthest position from the input region, and the dummy wiring extends through the peripheral region along the second, third and fourth sides of the input region, and electrically connects to at least one dummy wiring terminal.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a continuation of U.S. application Ser. No. 12/954,976, filed Nov. 29, 2010, the contents of which are incorporated herein by reference. 
     
    
     CLAIM OF PRIORITY 
       [0002]    The present application claims priority from Japanese Patent Application JP 2009-273054 filed on Dec. 1, 2009, the content of which is hereby incorporated by reference into this application. 
       BACKGROUND OF THE INVENTION 
       [0003]    The present invention relates to a touch panel and a display device with a touch panel, and more particularly, to a technique preferably applicable to wiring formed outside an input region. 
       DESCRIPTION OF RELATED ART 
       [0004]    In recent years, for propagation of mobile devices, a touch panel technique to support a “user friendly” graphical user interface has become more important. 
         [0005]    As this touch panel technique, an electrostatic capacitive coupling type touch panel is known. As this electrostatic capacitive coupling type touch panel, a touch panel, where a touch position in which an observer&#39;s finger has touched is detected, is disclosed in JPA 2008-310550. 
         [0006]    In this specification, an electrostatic capacitive coupling type touch panel is also called as an electrostatic capacitance type touch panel. They are also may be called a capacitive sensor. A touch panel may be called a touch sensor. 
         [0007]    In the touch panel disclosed in JPA 2008-310550, a coupling capacitance between an electrode in an X direction and an electrode in a Y direction is detected so as to detect coordinates of a position where an observer has touched. 
         [0008]      FIG. 7  is a plane view for explanation of the conventional electrostatic capacitive coupling type touch panel. 
         [0009]    As shown in  FIG. 7 , the conventional electrostatic capacitive coupling type touch panel has plural X electrodes  1  and plural Y electrodes  2  crossing the X electrodes  1 . 
         [0010]    The plural X electrodes  1  respectively have an electrode pattern where a first part  1   a  and a second part  1   b  having a width greater than that of the first part  1   a  are alternately arranged. The plural Y electrodes  2  respectively have an electrode pattern where a first part  2   a  and a second part  2   b  having a width greater than that of the first part  2   a  are alternately arranged. 
         [0011]    A region where the plural X electrodes  1  and the plural Y electrodes  2  are formed is an input region ERI. In a peripheral region provided around the input region ERI, plural wiring layers ML connected to the plural X electrodes  1  and the plural Y electrodes  2  are provided. 
         [0012]    Note that as shown in  FIG. 8 , the wiring layer ML has a transparent conductive layer (ITO; Indium Tin Oxide)  10  as a lower layer and a metal layer  11  of silver alloy material or the like. Note that  FIG. 8  is an enlarged view of a corner of the wiring layer ML show in  FIG. 7 . 
         [0013]    The above-described wiring layer ML is formed in a process as shown in  FIGS. 9A to 9D . 
         [0000]    (1) A transparent conductive film F 10  as a transparent conductive layer is formed on the entire surface of a substrate (e.g., a transparent substrate such as a glass substrate)  21  ( FIG. 9A ).
 
(2) Next, a metal film as the metal layer  11  is formed on the above-described transparent conductive film F 10 , and the metal layer  11  as an upper layer of the wiring layer ML is formed with a series of photolithographic technique ( FIG. 9B ).
 
(3) Next, a resist film is formed on the metal layer  11  using e.g. positive resist, then irradiated with light (e.g., ultraviolet light) using a transparent conductive layer formation photomask MSK, then the resist film is selectively developed, thereby a resist film RF is left only on the metal layer  11  ( FIG. 9C ).
 
(4) Next, the transparent conductive film F 10  is etched by wet etching, thereby the resist film RF is removed, thus the transparent conductive film F 10  is formed ( FIG. 9D ).
 
         [0014]    Note that generally, as shown in  FIG. 10 , in the transparent conductive layer formation photomask MSK, a mask pattern MPA for forming the transparent conductive layer  10  is formed, with a chrome (Cr) film, on a light (e.g. ultraviolet light) transmitting substrate MSB. 
         [0015]    As the surface of the transparent conductive layer formation photomask MSK is contaminated by chemical reaction or the like of the resist film RF upon light irradiation, it is necessary to clean the transparent conductive layer formation photomask MSK. 
         [0016]    However, the chrome film mask pattern MPA of the transparent conductive layer formation photomask MSK is deteriorated by the cleaning. Especially, the deterioration of the chrome film mask pattern MPA is serious at a corner of the wiring layer ML formed in a position farthest from the input region ERI. 
         [0017]    Accordingly, it is conceivable that as shown in  FIGS. 11A and 11B , the pattern of the resist film RF becomes thin due to the deterioration of the chrome film mask pattern MPA of the transparent conductive layer formation photomask MSK, then the corners become rounded, and a part of the metal layer  11  is protruded from the resist film RF. Note that  FIGS. 11A and 11B  are cross-sectional views showing the resist film RF, formed on the metal layer  11  using the transparent conductive layer formation photomask MSK in which the chrome film mask pattern MPA is deteriorated. 
         [0018]    In the state shown in  FIGS. 11A and 11B , when wet etching is performed so as to form the transparent conductive layer  10 , the etchant erodes and etches the metal layer  11  as shown in  FIG. 12 , accordingly, the wiring layer ML becomes chipped or wire-broken. 
       SUMMARY OF THE INVENTION 
       [0019]    The present invention has been made so as to address the above-described problem of the conventional technique, and provides a technique in a touch panel to prolong a period before wiring formed outside an input region is chipped or wire-broken due to deterioration of a mask pattern. 
         [0020]    Among aspects of the present invention disclosed in the present application, the outline of typical aspect is as follows. 
         [0021]    According to an aspect of the present invention, provided is an electrostatic capacitive coupling type touch panel having: an input region; and a plurality of wirings formed around the input region, the input region having a plurality of X electrodes and a plurality of Y electrodes crossing the X electrodes, the plurality of wirings respectively being connected to corresponding electrodes of the plurality of X electrodes and the plurality of Y electrodes, wherein the plurality of wirings respectively have: a conductive layer; and a metal layer formed on the conductive layer, wherein the conductive layer is formed to have a width greater than that of the metal layer, wherein the plurality of wirings have a corner, and wherein, in a wiring provided in a farthest position from the input region, among the plurality of wirings, the corner of the metal layer is chamfered. 
         [0022]    In the touch panel, assuming that a width of a chamfered portion of the metal layer at the corner of the wiring formed in the farthest position from the input region is W1, and a mean value of the widths of the metal layers in linear portions of the wiring formed in the farthest position from the input region is W2, 0.8×W2≦W1≦1.2×W2 is satisfied. 
         [0023]    Further, according to another aspect of the present invention, provided is an electrostatic capacitive coupling type touch panel having: an input region; and a plurality of wirings formed around the input region, the input region having a plurality of X electrodes and a plurality of Y electrodes crossing the X electrodes, the plural wirings respectively being connected to corresponding electrodes of the plurality of X electrodes and the plurality of Y electrodes, wherein the plurality of wirings respectively have: a conductive layer; and a metal layer formed on the conductive layer, wherein the conductive layer is formed to have a width greater than that of the metal layer, and wherein a dummy wiring, not connected to any of the plurality of X electrodes or the plurality of Y electrodes, is provided outside the wiring formed in a farthest position from the input region, among the plurality of wirings. 
         [0024]    In the touch panel, the dummy wiring is supplied with a reference voltage. 
         [0025]    In any one of the above-described touch panels, the conductive layer has a transparent conductive film. 
         [0026]    In any one of the touch panel, the plurality of wirings respectively have an upper conductive layer provided on the metal layer with an insulating film therebetween, and the upper conductive layer is electrically connected to the conductive layer of the plurality of wirings. 
         [0027]    In the above-described touch panel, the conductive layer and the upper conductive layer have a transparent conductive film. 
         [0028]    In any one of the above-described touch panels, the X electrode and the Y electrode have a transparent conductive film. 
         [0029]    In any one of the above-described touch panels, the X electrode and the Y electrode are formed with an insulating film therebetween. 
         [0030]    In any one of the above-described touch panels, the X electrode and the Y electrode have an intersection part between the X electrode and the Y electrode and an electrode part formed between two intersection parts, the electrode part and the intersection part of the X electrode and the electrode part of the Y electrode are formed on the same layer, and the intersection part of the Y electrode is formed on a different layer, with an insulating layer therebetween. 
         [0031]    Further, according to another aspect of the present invention, provided is a display device with touch panel wherein any one of the electrostatic capacitive coupling type touch panel is provided on a surface of a display panel on the observer side. 
         [0032]    Among aspects of the present invention disclosed in the present application, the effects of typical aspect are as follows. 
         [0033]    In accordance with the touch panel according to the present invention, it is possible to prolong a period before wiring formed on the outside of an input region is chipped or wire-broken due to deterioration of a mask pattern. 
         [0034]    Other features and advantages of the present invention will be apparent from the following description taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]      FIG. 1  is a plane view showing an electrode pattern of an electrostatic capacitance type touch panel as a presupposed element of the present invention; 
           [0036]      FIG. 2  is a cross-sectional view showing a structure along a line A-A′ in  FIG. 1 ; 
           [0037]      FIG. 3  is a cross-sectional view showing a structure along a line B-B′ in  FIG. 1 ; 
           [0038]      FIG. 4  is an enlarged view of a corner of a wiring layer provided in a farthest position from an input region among plural wiring layers provided in a peripheral region of the electrostatic capacitance type touch panel in an embodiment of the present invention; 
           [0039]      FIG. 5  is a schematic view of an arrangement of wiring layers ML provided in the peripheral region of the electrostatic capacitance type touch panel in the embodiment of the present invention; 
           [0040]      FIG. 6  is a schematic view of a display device with touch panel using the electrostatic capacitance type touch panel in the respective embodiments of the present invention; 
           [0041]      FIG. 7  is a plane view for explanation of a conventional electrostatic capacitive coupling type touch panel; 
           [0042]      FIG. 8  is an enlarged view of a corner of the wiring layer ML in  FIG. 7 ; 
           [0043]      FIGS. 9A to 9D  are cross-sectional views for explanation of a manufacturing method of the wiring layer in  FIG. 7 ; 
           [0044]      FIG. 10  is a cross-sectional view for explanation of a transparent conductive layer formation photomask; 
           [0045]      FIGS. 11A and 11B  are cross-sectional views showing the resist film RF, formed on the metal layer  11  using the transparent conductive layer formation photomask in which a chrome film mask pattern is deteriorated; and 
           [0046]      FIG. 12  is a cross-sectional view showing the wiring layer after etching in the state shown in  FIG. 11 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0047]    Hereinbelow, embodiments of the present invention will be described in detail in accordance with the accompanying drawings. 
         [0048]    Note that in all the figures for explanation of the embodiments, elements having the same function will have the same reference numerals and repeated explanations thereof will be omitted. 
       [Structure of Touch Panel as Presupposed Element of Present Invention] 
       [0049]      FIG. 1  is a plane view showing an electrode pattern of an electrostatic capacitance type touch panel as a presupposed element of the present invention. 
         [0050]      FIG. 2  is a cross-sectional view showing a structure along a line A-A′ in  FIG. 1 . 
         [0051]      FIG. 3  is a cross-sectional view showing a structure along a line B-B′ in  FIG. 1 . 
         [0052]    An electrostatic capacitance type touch panel  20 , as a presupposed element of the present invention, has plural X electrodes  1 , extended in a first direction (e.g. in an X direction) and provided in parallel at a predetermined array pitch in a second direction (e.g. a Y direction) crossing the first direction, and plural Y electrodes  2  extended in the second direction crossing the plural X electrodes  1  and provided in parallel at a predetermined array pitch in the first direction, on the surface of a substrate  21  on the observer side. 
         [0053]    The plural Y electrodes  2  respectively have an electrode pattern where a first part  2   a  and a second part  2   b  having a width greater than that of the first part  2   a  are alternately arranged in the second direction. The plural Y electrodes  2  are provided on the surface of the substrate  21  on the observer side. As the substrate  21 , a transparent insulating substrate such as a glass substrate is used. 
         [0054]    The plural X electrodes  1  respectively have an electrode pattern where a first part  1   a  and a second part  1   b  having a width greater than that of the first part  1   a  are alternately arranged in the first direction. The first parts  1   a  of the plural X electrodes  1  are provided on an insulating film  12  formed on the surface of the substrate  21  on the observer side. 
         [0055]    The second parts  1   b  of the plural X electrodes  1  are formed separately from the Y electrodes  2  on the surface of the substrate  21  on the observer side. Note that the first parts  1   a  of the plural X electrodes  1  are covered with a protective film  13  formed as an upper layer. 
         [0056]    The first part  1   a  of the X electrode  1  two-dimensionally crosses the first part  2   a  of the Y electrode  2 , and electrically connected to two adjacent second parts  1   b  with the first part  2   a  therebetween via a contact hole  12   a  formed in an insulating film  12  as an interlayer insulating film between the first part  1   a  of the X electrode  1  and the Y electrode  2 . 
         [0057]    In a plan view, the second part  2   b  of the Y electrode  2  is provided between the respective first parts  1   a  of two adjacent X electrodes  1 . Also in a plan view, the second part  1   b  of the X electrode  1  is provided between the respective first parts  2   a  of two adjacent Y electrodes  2 . That is, the Y electrode  2  has a portion wider than the width of a portion crossing the X electrode  1  between the X electrodes  1 , and the X electrode  1  has a portion wider than the width of a portion crossing the Y electrode  2  between the Y electrodes  2 . 
         [0058]    A region where the plural Y electrodes  2  and X electrodes  1  are provided is an input region ERI. As shown in  FIG. 1 , plural wiring layers ML electrically connected to the respective plural Y electrodes  2  and the respective plural X electrodes  1  are provided around the input region ERI. The plural wiring layers ML electrically connect the plural Y electrodes  2  and the plural X electrodes  1  to drive circuits. 
         [0059]    As shown in  FIGS. 2 and 3 , the plural wiring layers ML are provided on the surface (main surface) of the substrate  21  on the observer side, and covered with an insulating film  12  formed as an upper layer. The plural wiring layers ML are electrically connected to corresponding electrodes (the X electrodes  1  and the Y electrodes  2 ) at ends of the respective electrodes (the X electrodes  1  and the Y electrodes  2 ). 
         [0060]    The plural X electrodes  1  and the plural Y electrodes  2  are formed with transparent conductive material or the like having high transparency such as ITO (Indium Tin Oxide). Further, the wiring layer ML has a transparent conductive layer  10  formed of transparent conductive material such as ITO as a lower layer and a metal layer  11  formed of e.g. silver alloy as an upper layer. 
         [0061]    Further, each of the plural wiring layers ML is formed on the metal layer  11  with the insulating film  12  therebetween, and has an upper transparent conductive layer  10 U of transparent conductive material such as ITO. The upper transparent conductive layers  10 U are electrically connected to the respective transparent conductive layers  10  of the plural wiring layers ML via contact holes  12   b  formed in the insulating film  12  near the terminals of the wiring layer ML. 
         [0062]    The touch panel  20  in the present embodiment receives a signal outputted from the drive circuit via a wiring on a flexible printed circuit board connected to one side of the touch panel  20 . 
         [0063]    Note that through holes are formed in the wirings on the flexible printed circuit board, and the wiring is electrically connected to crossing wiring on the rear side via the through hole. The crossing wirings cross a large number of wirings, and again connected to the wirings via through holes formed at the other end. In the present embodiment with this arrangement, the respective plural X electrodes  1  and plural Y electrodes  2  are supplied with driving voltages outputted from the drive circuits from both sides. 
         [0064]    Next, the method of manufacturing the electrostatic capacitance type touch penal  20  as a presupposed element of the present invention will be described with reference to  FIGS. 1 to 3 . 
         [0000]    (1) First, a first transparent conductive film as a transparent conductive layer is formed on the entire surface of the substrate (e.g. a transparent substrate such as a glass substrate)  21  on the observer side (see above-described  FIG. 9A ).
 
(2) Next, a metal film as the metal layer  11  is formed on the above-described first transparent conductive film, and the metal layer  11  as an upper layer of the wiring layer ML is formed by the photolithographic technique (see above-described  FIG. 9B ).
 
(3) Next, a first mask having an electrode pattern and wiring layer conductive film pattern is formed using e.g. positive resist on the metal layer  11 . Then the first transparent conductive film is etched using the above-described first mask as an etching mask, thereby the plural Y electrodes  2 , the second parts  1   b  of the plural X electrodes  1 , and the transparent conductive layer  10  as a lower layer of the wiring layer ML are formed (see above-described  FIGS. 9C and 9D ). In this process, respective ends of the X electrodes  1  and the Y electrodes  2  are electrically connected to corresponding wiring layers ML.
 
(4) Next, the above-described first mask is removed, then, the insulating film  12  of e.g. negative resist is formed on the substrate  21  including the plural Y electrodes  2 , the second parts  1   b  of the plural X electrodes  1  and the wiring layers ML. In this process, the plural Y electrodes  2 , the second parts  1   b  of the plural X electrodes  1  and the wiring layers ML are covered with the insulating film  12 .
 
(5) Next, the contact holes  12   a  and  12   b  are formed in necessary positions of the insulating film  12 , then, a second transparent conductive film as a transparent conductive layer is formed on the entire surface of the Insulating film  12  including the contact holes  12   a  and  12   b.  
 
(6) Next, a second mask having a pattern of the first parts  1   a  of the plural X electrodes  1  and the wiring layers LM is formed using e.g. positive resist on the transparent conductive film, then, the above-described second transparent conductive film is etched using the above-described second mask as an etching mask, thereby the first parts  1   a  of the plural X electrodes  1   a  and the upper transparent conductive layers  10 U of the wiring layers ML are formed on the insulating film  12 . In this process, the first parts  1   a  of the upper-layer plural X electrodes  1  are electrically connected to the second parts  1   b  of the lower-layer X electrodes  1  via the contact holes  12   a . Further, the upper transparent conductive layers  10 U of the respective wiring layers ML are electrically connected to the transparent conductive layers  10  of the respective wiring layers ML via the contact holes  12   b.  
 
(7) Next, the above-described second mask is removed, then the protective film  13  of e.g. negative resist is formed on the insulating film  12  including the first parts  1   a  of the plural X electrodes  1  and the upper transparent conductive layers  10 U, thereby the structure shown in  FIGS. 1 to 3  is obtained. In this process, the first parts  1   a  of the X electrodes  1  and the upper transparent conductive layers  10 U are covered with the protective film  13 .
 
         [0065]    Note that in the above explanation, it may be arranged such that the X electrodes  1  and the Y electrodes  2  are formed on different layers. For example, the Y electrodes  2  may be formed on the insulating film  12 . In this case, it is necessary to electrically connect the Y electrodes  2  to the wiring layers ML via the contact holes formed in the insulating film  12 . 
       Embodiment 1 
       [0066]      FIG. 4  is an enlarged view of a corner of the wiring layer ML provided in a farthest position from the input region ERI among plural wiring layers ML provided in the peripheral region of the electrostatic capacitance type touch panel  20  in an embodiment 1 of the present invention. 
         [0067]    As shown in  FIG. 4 , as the feature of the present embodiment, the pattern of a mask for formation of the metal layer  11  as an upper layer of the wiring layer ML is changed and the metal layer  11  is chamfered at corners of the wiring layer ML. Assuming that the minimum width (the width of a narrowest portion) of the chamfered portion of the metal layer  11  at a corner of the wiring layer ML is W1, and a mean value of widths of the metal layer  11  in linear portions of the wiring layer ML formed in the farthest position from the input region is W2, 0.8×W2≦W1≦1.2×W2 is satisfied. 
         [0068]    In this arrangement, in the present embodiment, as shown in  FIGS. 11A and 11B , even when the pattern of a resist film RF is thinned and the corners are rounded due to deterioration of a mask pattern MPA of a transparent conductive layer formation photomask MSK, a period before a part of the metal layer  11  is protruded from the resist film RF can be prolonged. That is, in the present embodiment, the tolerance to the protrusion of the metal layer  11  as an upper layer of the wiring layer ML from the resist film RF can be improved. 
         [0069]    Accordingly, in the present embodiment, since a period before the wiring layer ML is chipped or wire-broken due to deterioration of the mask pattern MPA of the transparent conductive layer formation photomask MSK can be prolonged, the tolerance to wire-breakage of the wiring layer ML due to deterioration of the mask pattern MPA of the transparent conductive layer formation photomask MSK can be improved. 
       Embodiment 2 
       [0070]      FIG. 5  is a schematic view of an arrangement of the wiring layers ML provided in the peripheral region of the electrostatic capacitance type touch panel  20  in an embodiment 2 of the present invention. 
         [0071]    As shown in  FIG. 5 , as the feature of the present embodiment, a dummy wiring layer MLD is formed outside the wiring layer ML provided in the farthest position from the input region ERI among the plural wiring layers ML. In the present embodiment, as in the case of the respective wiring layers ML, the dummy wiring layer MLD, having the transparent conductive layer  10  as a lower layer, the metal layer  11  as an upper layer and the upper transparent conductive layer  10 U, is provided at the same interval as that of the respective wiring layers ML. Further, the dummy wiring layer MLD is not electrically connected to any of the plural Y electrodes  2  or the plural X electrodes  1 . 
         [0072]    Generally, the mask pattern MPA of the transparent conductive layer formation photomask MSK is deteriorated in the cleaning process for the transparent conductive layer formation photomask MSK. The deterioration of the transparent conductive layer formation mask pattern MPA of the outermost wiring layer ML is extremely serious, while the deterioration of the transparent conductive layer formation mask pattern MPA in an inner position is extremely slight. 
         [0073]    Accordingly, in the present embodiment, since a period before the pattern of the resist film RF is thinned and the corners are rounded due to the deterioration of the mask pattern MPA of the transparent conductive layer formation photomask MSK can be prolonged, the period before a part of the metal layer  11  is protruded from the resist film RF can be prolonged. Accordingly, in the present embodiment, since the period before the wiring layer ML is chipped or wire-broken due to the deterioration of the mask pattern MPA of the transparent conductive layer formation photomask MSK can be prolonged, the tolerance to breakage of the wiring layer ML due to the deterioration of the mask pattern MPA of the transparent conductive layer formation photomask MSK can be improved. Note that in the present embodiment, it may be arranged such that a ground potential or the like is supplied to the dummy wiring layer MLD. 
         [0074]      FIG. 6  is a schematic view of a display device with touch panel using the electrostatic capacitance type touch panel in the above-described embodiments. 
         [0075]    The display device with touch panel shown in  FIG. 6  has a liquid crystal display panel  30 , the electrostatic capacitance type touch panel  20  in the above-described embodiments, provided on the surface of the liquid crystal display panel  30  on the observer side, and a backlight  40  provided under the surface of the liquid crystal display panel  30  on the side opposite to the observer side. As the liquid crystal display panel  30 , an IPS type liquid crystal display panel, a TN type liquid crystal display panel, a VA type liquid crystal display panel or the like is used. The liquid crystal display panel  30  has a display region where plural pixels are provided in a matrix array and a non-display region provided around the display region. 
         [0076]    Further, in  FIG. 6 , the display device with touch panel in which the touch panel is provided on the liquid crystal display panel is described as an example of the display panel. However, the present invention is not limited to this arrangement. The present invention is also applicable to a display device with touch panel in which the touch panel is provided on another display panel such as an organic EL display panel or an inorganic EL display panel. 
         [0077]    The present invention made by the inventors has been specifically described based on the above-describe embodiments. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the scope of the present invention.