Patent Publication Number: US-2011050636-A1

Title: Input device and display device provided with the same

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an input device and a display device provided with the same. 
     2. Description of the Related Art 
     An input device is provided with a detection electrode to detect an input position, and a wiring conductor to apply a voltage to this detection electrode, on a base body (see Japanese Patent Application Laid-Open No. 8-328721, for example). 
     Recently, the input device is required to be improved in detection accuracy of an input position. 
     The present invention has been made in this respect, and it is an object of the present invention to improve detection accuracy of an input position. 
     SUMMARY OF THE INVENTION 
     An input device according to one embodiment of the present invention has an input region and an outside region positioned outside the input region. The input device includes a base body having translucency, a detection electrode configured to detect an input position, and a wiring conductor configured to apply a voltage to the detection electrode. The detection electrode is provided in the input region and on the base body. The wiring conductor is provided in the outside region and on the base body. The input device further includes an insulation film which covers the wiring conductor and is provided in the outside region, and a conductor film provided on the insulation film so as to be opposed to the wiring conductor in a thickness direction of the insulation film. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view showing an input device according to a first embodiment of the present invention; 
         FIGS. 2A and 2B  are cross-sectional views of the input device shown in  FIG. 1 , in which  FIG. 2A  is the cross-sectional view taken along a line Ib-Ib, and  FIG. 2B  is the cross-sectional view taken along a line IIb-IIb; 
         FIG. 3  is a cross-sectional view of the input device shown in  FIG. 1  taken along a line IIIb-IIIb in  FIG. 1 ; 
         FIGS. 4A to 4F  are cross-sectional views showing production steps of the input device shown in  FIG. 1  taken along a line IIIb-IIIb in  FIG. 1 ; 
         FIGS. 5A and 5B  are plan views showing a region in which a wiring insulation film and a conductor film of the input device shown in  FIG. 1  are formed; 
         FIG. 6  is a cross-sectional view showing a display device according to an embodiment of the present invention; 
         FIG. 7  is a perspective view showing a liquid crystal display panel; 
         FIG. 8  is a cross-sectional view showing an essential part of an input device according to a second embodiment of the present invention; 
         FIG. 9  is a cross-sectional view showing an essential part of a variation of the input device according to the embodiment of the present invention; and 
         FIG. 10  is a cross-sectional view showing an essential part of another variation of the input device according to the embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     First Embodiment 
     Referring to  FIGS. 1 to 3 , an input device X 1  according to a first embodiment of the present invention is described. 
     The input device X 1  is a capacitance type touch panel. As shown in  FIGS. 1 to 3 , the input device X 1  includes a base body  10 , a first detection electrode pattern  20 , a second detection electrode pattern  30 , and an electrode insulation film  40 , a wiring insulation film K, and a conductor film H. 
     As shown in  FIG. 1 , the input device X 1  has an input region E I  which a user touches with a finger and the like to input information, and an outside region E O  positioned outside the input region E I . The outside region E O  includes an external connection region  11  serving as a region electrically connected to a FPC (Flexible Printed Circuit) provided outside the drawing. 
     The base body  10  supports the first detection electrode pattern  20 , the second detection electrode pattern  30 , the electrode insulation film  40 , the wiring insulation film K, and the conductor film H. The base body  10  has a lower main surface on which the first and the second detection electrode patterns  20  and  30  etc. are formed, and an upper main surface which a user touches with a finger or an input tool such as a touch pen in order to input information. Thus, a user can input information with a finger or an input tool through the base body  10  without directly touching the first detection electrode pattern  20  and the second detection electrode pattern  30 . In this embodiment, the base body  10  is in the shape of a rectangle in planar view, but not limited to such a shape. The base body  10  is formed of a material having translucency and insulation properties such as glass or plastics. Here, the translucency means that it transmits visible light. 
     The first detection electrode pattern  20  has a first detection electrode  21 , a first connection electrode  22 , and a first wiring conductor  23 . 
     The first detection electrode  21  has a role to detect a position of a finger F moving closer to the input device X 1  in an arrow direction CD. The first detection electrode  21  is provided in the input region E I  and provided on the base body  10 . The first detection electrodes  21  are arranged along an arrow direction AB and the arrow direction CD at intervals in the shape of a matrix, and the first detection electrodes  21  adjacent to each other in the arrow direction AB are electrically connected to each other by the first connection electrode  22 . As shown in  FIG. 1 , the first detection electrode  21  is in the shape of a diamond in planar view, but not limited to such a shape. The first detection electrode  21  is formed of a material having translucency and conductivity such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), ATO (Antimony Tin Oxide), tin oxide, or zinc oxide. 
     The first detection electrode  21  is formed as follows. First, an ITO film is formed on the base body  10  by a sputtering method, evaporation method, or chemical vapor deposition (CVD) method. Then, a photosensitive resin is applied onto the ITO film, and the film is patterned through exposing, developing, etching steps, whereby the first detection electrode  21  is formed. 
     The first connection electrode  22  has a role to electrically connect the adjacent first detection electrodes  21  to each other. The first connection electrode  22  is provided in the input region E I  and is provided on the base body  10 . As shown in  FIGS. 2A and 2B , the first connection electrode  22  is opposed to a second connection electrode  32  with the electrode insulation film  40  interposed therebetween. That is, the first connection electrode  22  intersects with the second connection electrode  32  in planar view. In addition, an area of the first connection electrode  22  in planar view is smaller than an area of the first detection electrode  21  in planar view. The first detection electrode pattern  20  intersects with the second detection electrode pattern  30  at connection electrodes of which an area is smaller than an area of detection electrodes. Accordingly, the intersection region of the detection electrode patterns can be small. Thus, a floating charge at the intersection region of the detection electrode patterns can be small, so that detection accuracy of the input device X 1  can be improved. The first connection electrode  22  is formed of the same material as that of the first detection electrode  21 . The first connection electrode  22  can be formed by the same method as that of the first detection electrode  21 . 
     The first wiring conductor  23  has a role to apply a voltage to the first detection electrode  21 . The first wiring conductor  23  is provided in the outside region E O  and provided on the base body  10 . One end of the first wiring conductor  23  is electrically connected to the first detection electrode  21  positioned at the end among the first detection electrodes  21 , and the other end thereof is positioned in the external connection region  11 . 
     The first wiring conductor  23  is formed of a material having conductivity such as aluminum, chrome, gold, silver, copper or an alloy of them, or the same material as that of the first detection electrode  21 . As shown in  FIG. 3 , the first wiring conductor  23  is provided in such a manner that a metal film  23   b  formed of aluminum, aluminum alloy, silver, or silver alloy, is laminated on a conductor pattern  23   a  formed of a translucent material such as ITO. Thus, the first wiring conductor  23  is low in resistance value, and a current is likely to flow therein, and detection speed of an input position is improved. The first wiring conductor  23  can be formed by the same method as that of the first detection electrode  21 . 
     The wiring insulation film K is provided on the base body  10  so as to cover the first wiring conductor  23 . In addition, the wiring insulation film K is provided in the outside region E O  and is provided on the base body  10 . The wiring insulation film K is formed of a resin such as an acrylic resin, or epoxy resin. 
     The wiring insulation film K is formed by applying the above material onto the base body  10 , and then exposing and developing it. If a foreign material such as dust comes to be mixed in the above material during forming the wiring insulation film K, a hole could be generated in the wiring insulation film K due to the foreign material when hardening the material to form the wiring insulation film K. As a result, water in the air could enter the wiring insulation film K through the hole and comes in contact with the first wiring conductor  23 , and the first wiring conductor  23  could become eroded. Similarly, in a process for forming the first and the second detection electrode patterns  20  and  30 , if a chemical solution such as an etching solution enters the hole and the etching solution comes in contact with the first wiring conductor  23 , the first wiring conductor  23  could become eroded. 
     In a case that pigment particles are included in the wiring insulation film K, a depth of the hole can be smaller. Therefore, the chemical solution is less likely to come in contact with the first wiring conductor. As a result the first wiring conductor  23  is less likely to be eroded. 
     The conductor film H is formed of a conductive material such as aluminum, chrome, gold, silver, copper, or an alloy of them or the same material as that of the first detection electrode  21 . 
     In addition, the conductor film H is provided on the wiring insulation film K so as to be opposed to the first wiring conductor  23  in a thickness direction of the wiring insulation film K. Therefore, an electric field generated from a display device, which may cause a noise to the first wiring conductor  23 , is absorbed by the conductor film H, and an influence of a noise on the first wiring conductor  23  can be reduced. Therefore, the detection accuracy of the input position is improved. 
     The conductor film H is preferably connected to a conductor having a reference potential such as the ground potential. In this case, if the input device X 1  is incorporated in the display device, the noise generated in the first wiring conductor  23  is further reduced. 
     In addition, when the wiring insulation film K is formed of the resin, the wiring insulation film K is likely to absorb water in the air. Therefore, if the absorbed water comes in contact with the first wiring conductor  23 , the first wiring conductor  23  could become eroded. However, since the conductor film H is provided on the wiring insulation film K in the input device X 1 , the water in the air is less likely to be absorbed by the wiring insulation film K, and the first wiring conductor  23  is less likely to be eroded. 
     The conductor film H is preferably provided so as to cover the first wiring conductor  23  in planar view. Thus, the first wiring conductor  23  is less likely to be affected by the electric field generated from the display device, and the wiring insulation film K is less likely to absorb the water in the air. In addition, it is further preferable that the conductor film H is provided on a whole surface S including a main surface Sa and an end surface Sb of the wiring insulation film K. 
     As long as the wiring insulation film K is provided in a region surrounded by a chain line in  FIG. 5A , that is, a region in which the first wiring conductor  23  and the second wiring conductor  33  are formed, any pattern or shape of the wiring insulation film K is applicable. It is preferable that the wiring insulation film K is provided on the whole region of the outside region Eo like a region surrounded by a chain line in  FIG. 5B  because the input device is improved in flatness. 
     As long as the conductor film H is provided in the region in which the first wiring conductor  23  and the second wiring conductor  33  are formed, any pattern or shape of the conductor film H is applicable. It is preferable that the conductor film H is formed in the region surrounded by the chain line in  FIG. 5A  or  5 B, that is, in the same region as that of the wiring insulation film K because the wiring insulation film K is much less likely to absorb the water in the air. 
     In addition, the conductor film H is preferably formed of the same material as that of the first detection electrode  21  and the second detection electrode  31 . In this case, the first detection electrode  21 , the second detection electrode  31 , and the conductor film H can be formed in the same process. Therefore, the number of production steps of the input device X 1  can be reduced. 
     The second detection electrode pattern  30  has a second detection electrode  31 , the second connection electrode  32 , and the second wiring conductor  33 . 
     The second detection electrode  31  has a role to detect a position of the finger F moving closer to the input device X 1  in the arrow direction AB. The second detection electrode  31  is provided in the input region E I  and is provided on the base body  10 . The second detection electrodes  31  are arranged along the arrow direction AB and the arrow direction CD at intervals in the shape of a matrix, and the second detection electrodes  31  adjacent to each other in the arrow direction CD are electrically connected to each other by the second connection electrode  32 . The second detection electrode  31  is in the shape of a diamond in planar view. The second detection electrode  31  is formed of the same material as that of the first detection electrode  21 . In addition, a method of forming the second detection electrode  31  is the same as that of the first detection electrode  21 . 
     The second connection electrode  32  has a role to electrically connect the adjacent second detection electrodes  31  to each other. The second connection electrode  32  is provided in the input region E I  and is provided on the base body  10 . As shown in  FIGS. 2A and 2B , the second connection electrode  32  is opposed to the first connection electrode  22  with the electrode insulation film  40  interposed therebetween. The second connection electrode  32  is formed of the same material as that of the first detection electrode  21 . In addition, a method of forming the second connection electrode  32  is the same as that of the first detection electrode  21 . 
     The second wiring conductor  33  has a role to apply a voltage to the second detection electrode  31 . The second wiring conductor  33  is provided on the base body  10 . One end of the second wiring conductor  33  is electrically connected to the second detection electrode  31  positioned at the end among the second detection electrodes  31 , and the other end thereof is positioned in the external connection region  11 . In addition, the second wiring conductor  33  is formed of the same material as that of the first wiring conductor  23 . Furthermore, a method of forming the second wiring conductor  33  is the same as that of the first detection electrode  21 . 
     Like the first wiring conductor  23 , the second wiring conductor  33  is covered with the wiring insulation film K. In addition, the conductor film H is formed on the wiring insulation film K. 
     The electrode insulation film  40  has a role to insulate the first connection electrode  22  and the second connection electrode  32 . The electrode insulation film  40  is provided on the base body  10 , and positioned between the first connection electrode  22  and the second connection electrode  32 . The electrode insulation film  40  is formed of the same material as that of the wiring insulation film K. In addition, a method of forming the electrode insulation film  40  is the same as that of the wiring insulation film K. 
     Regarding the input device X 1 , the conductor film H is provided on the wiring insulation film K so as to be opposed to the first wiring conductor  23  and the second wiring conductor  33  in the thickness direction of the wiring insulation film K. Therefore, since the electric field generated from the display device is absorbed by the conductor film H, a noise generated in the first wiring conductor  23  and the second wiring conductor  33  is reduced. Thus, the detection accuracy of the input position can be improved. 
     In addition, the conductor film H can reduce the water absorbed in the wiring insulation film K, and the first wiring conductor  23  and the second wiring conductor  33  can be less likely to be eroded. 
     Next, a method of producing the input device X 1  is described with reference to  FIGS. 4A to 4F .  FIGS. 4A to 4F  are cross-sectional views showing production steps taken along a line IIIb-IIIb in  FIG. 1 . 
     As shown in  FIG. 4A , a film M 1  is formed of a translucent material such as ITO on the base body  10  by the sputtering method. Then, a photosensitive resin is applied onto a surface of the film M 1 , and the film M 1  is patterned as shown in  FIG. 4B  through exposing, developing, and etching steps, and a step of removing the photosensitive resin. Thus, the first connection electrode  22  and the conductor pattern  23   a  are formed. 
     Then, a metal film formed of aluminum is formed on the base body  10  and patterned in the same way as the above. Thus, as shown in  FIG. 4C , the conductor pattern  23   a  is covered with the metal film  23   b , whereby the first wiring conductor  23  having a laminated structure is formed. 
     Then, an insulation material such as an acrylic resin is applied to the base body  10 , and exposed, developed, and hardened. Thus, as shown in  FIG. 4D , the electrode insulation film  40  is formed on the first connection electrode  22 , and the wiring insulation film K is formed on the first wiring conductor  23 . If a foreign material such as dust is contained in the insulation material in this step, a hole could be formed in the wiring insulation film K when hardening the insulation material due to the foreign material. 
     Then, as shown in  FIG. 4E , a film M 2  is formed of a translucent material such as ITO on the base body  10 . At the same time, the conductor film H is formed on the wiring insulation film K so as to be opposed to the first wiring conductor  23 . 
     Then, the film M 2  is patterned. At the time of patterning, an etching solution to etch away a part of the film M 2  comes over to the wiring insulation film K. However, even when the hole is generated in the wiring insulation film K, the etching solution is less likely to enter the hole of the wiring insulation film K because the conductor film H is formed on the wiring insulation film K. That is, the etching solution is less likely to come in contact with the first wiring conductor  23 . 
     Through the above production steps, the input device X 1  is produced as shown in  FIG. 4F . 
     In addition, the production method of the input device X 1  is not limited to this. While the film M 2  and the conductor film H are formed at the same time in the above production method, the film M 2  may be formed and patterned after the conductor film H has been formed. 
     The conductor film H is provided on the wiring insulation film K so as to be opposed to the first wiring conductor  23  and the second wiring conductor  33  in the thickness direction of the wiring insulation film K. Therefore, even when the hole is generated in the wiring insulation film K due to a foreign material such as dust, the etching solution can be less likely to come in contact with the first wiring conductor  23  and the second wiring conductor  33  due to the conductor film H. As a result, the first wiring conductor  23  and the second wiring conductor  33  can be less likely to be eroded. 
     In addition, in the input device X 1 , the first detection electrode  21  and the second detection electrode  31 , and the conductor film H are formed of the same material. Thus, the first detection electrode  21  and the second detection electrode  31 , and the conductor film H can be formed in the same process. As a result, the number of production steps of the input device X 1  can be reduced, and productivity of the input device X 1  can be improved. 
     As shown in  FIG. 6 , a display device Y is composed of the input device X 1  and a liquid crystal display device Z. In addition, the liquid crystal display device Z is composed of a liquid crystal display panel  60 , a light source device  70 , and a case  80 . 
     As shown in  FIG. 7 , the liquid crystal display panel  60  is composed of a first base body  61 , a second base body  62 , and a sealing member  63 , and a display region P composed of a plurality of pixels to display an image is formed by interposing a liquid crystal layer (not shown) between the first base body  61  and the second base body  62 , and sealing the liquid crystal layer with the sealing member  63 . 
     The light source device  70  has a role of applying light toward the liquid crystal display panel  60 , and arranged between the liquid crystal display panel  60  and a lower case  82 . 
     The case  80  is a member to house the liquid crystal display panel  60  and the light source device  70 , and has an upper case  81  and the lower case  82 . A material of the case  80  includes a resin such as a polycarbonate resin, or metal such as stainless (SUS) or aluminum. 
     The input device X 1  and the liquid crystal display device Z are bonded with a double-faced tape T. In addition, a fixing member used to fix the input device X 1  and the liquid crystal display device Z is not limited to the double-faced tape T, so that it may be a bonding member such as a thermosetting resin or ultraviolet curable resin, or a fixing body to physically fix the input device X 1  and the liquid crystal display device Z. 
     In addition, the conductor film H of the input device X 1  is positioned closer to the liquid crystal display panel  60  than the first wiring conductor  23  and the second wiring conductor  33 . Therefore, the electric field generated from the liquid crystal display panel  60  is absorbed by the conductor film H before it reaches the first wiring conductor  23  and the second wiring conductor  33 , and the detection accuracy of the input position can be much less likely to be lowered. 
     The display device Y is provided with the input device X 1  as described above. As a result, the first wiring conductor  23  and the second wiring conductor  33  can be less likely to be eroded. 
     Second Embodiment 
     Next, an input device X 2  according to a second embodiment of the present invention is described. The same references are assigned to the components having the same functions as those of the input device X 1 , and a description which overlaps with the input device X 1  is omitted. 
     As shown in  FIG. 8 , regarding the input device X 2 , a plurality of conductor films H are provided on a wiring insulation film K so as to be spaced with each other. 
     In addition, the plurality of conductor films H are spaced with each other, and opposed to each of first wiring conductors  23  to be electrically connected to them. Therefore, since a potential difference between the first wiring conductor  23  and the conductor film H opposed to the first wiring conductor  23  can be small, a floating charge between the first wiring conductor  23  and the conductor film H can be reduced. As a result, detection accuracy of an input position of the input device X 2  is improved. 
     In addition, regarding the input device X 2 , two wiring conductors  23  on the side of an arrow direction A among three first wiring conductors  23  shown in  FIG. 8  are each electrically connected to the opposed conductor films H through conduction through holes D. Meanwhile, a part of the first wiring conductor  23  on the side of an arrow direction B shown in  FIG. 8  is not covered with the wiring insulation film K. The first wiring conductor  23  can be electrically connected to the conductor film H at the part not covered with the wiring insulation film K. Thus, since it is not necessary to provide the conduction through hole D there, productivity of the input device X 2  is improved. 
     In addition, the first wiring conductor  23  and the conductor film H are electrically connected in the input device X 2 , but the conductor film H and the first wiring conductor  23  are not in contact with each other. Thus, an electric field from the display device Y can be less likely to affect the first wiring conductor  23  when the input device X 2  is incorporated in the display device. In addition, when the conductor film H is set to a reference potential such as the ground potential, the electric field can be much less likely to affect the first wiring conductor  23 . 
     In addition, since the conductor film H is provided on the wiring insulation film K in the input device X 2 , the wiring insulation film K is less likely to absorb water in the air, therefore, the first wiring conductor  23  can be less likely to be eroded. 
     In addition, the same effect can be provided in the display device Y even when the input device X 2  is employed therein instead of the input device X 1 . 
     Furthermore, the above embodiments are specific embodiments of the present invention, and various kinds of variations can be employed. Hereinafter, several variations are shown. 
     Regarding an input device X 3 , as shown in  FIG. 9 , a plurality of wiring insulation films K are provided on a base body  10  so as to cover a first wiring conductor  23 . Thus, a hole is less likely to be formed in the wiring insulation film K due to a foreign material such as dust. Therefore, the possibility that the first wiring conductor  23  becomes eroded can be further reduced. 
     Regarding an input device X 4 , as shown in  FIG. 10 , a protection substrate  50  is arranged so as to be opposed to a base body  10 . The protection substrate  50  has a function to prevent an external substance from directly coming in contact with a first detection electrode pattern  20  and a second detection electrode pattern  30 . The protection substrate  50  is formed of a material having preferable translucency to visible light such as well-known acrylic plate, glass plate, PET film, or polarization plate. 
     In addition, the base body  10  and the protection substrate  50  are bonded with a bonding member S. The bonding member S is formed of a translucent resin such as an acrylic resin, epoxy resin, or silicon resin. 
     In addition, while the first detection electrode pattern  20  and the second detection electrode pattern  30  are provided on the one base body  10  in the input device X 1 , the present invention is not limited to this. For example, two base bodies may be provided, and the first detection electrode pattern  20  may be provided on one of base bodies, and the second detection electrode pattern  30  may be provided on the other thereof. 
     In addition, the present invention can be applied to a resistive touch panel using an analog resistance film as well as a resistive touch panel using a matrix resistance film. 
     In addition, while the case where the display device Y is provided with the input device X 1  is described in the above, the input devices X 3  and X 4  may be employed therein instead of the input device X 1 . 
     Furthermore, while the case where the display panel is the liquid crystal display panel in the display device Y is described in the above, the present invention is not limited to this. More specifically, the display panel may be a CRT, plasma display, organic EL display, inorganic EL display, LED display, fluorescent display tube, field emission display, and surface-conduction electron-emitter display.