Patent Document

CLAIM OF PRIORITY 
     This application is a Divisional of U.S. patent application Ser. No. 13/401,758 filed on Feb. 21, 2012, which claims benefit of Japanese Patent Application No. 2011-075459 filed on Mar. 30, 2011, which are hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a surface panel mounted on a mobile device or other electronic devices and including a decorative layer and a touch sensor portion. The present invention particularly relates to a surface panel that can secure a wide display region and a sensing region in which a touch sensor portion performs sensing, and to a method of manufacturing the surface panel. 
     2. Description of the Related Art 
     A surface panel mounted on a mobile device or other electronic devices has a transmissive region through which a display screen, such as a liquid crystal display panel, can be seen and on which a touch operation is digitally performed, in its center portion. A frame-shaped colored decorative portion is mounted on the periphery of the transmissive region. 
     In a surface panel and with a method of manufacturing the surface panel described in Domestic Re-publication of PCT International Publication for Patent Application No. WO2008/149789, a capacitive touch sensor is stacked on a back surface of a glass substrate via a transparent pressure sensitive adhesive layer. By placing the glass substrate in a mold and injecting a melted resin into the mold, a frame-shaped decorative portion made of a synthetic resin is fixedly attached to the periphery of the glass substrate. 
     In an outer casing and with a method of manufacturing the outer casing described in Japanese Unexamined Patent Application Publication No. 2009-130283, a first film and a second film are included. The first film includes a light transmissive portion, a frame-shaped decorative portion surrounding the light transmissive portion, and a touch display portion formed on part of the decorative portion. The second film has electrodes of a touch sensor formed thereon. After the first and second films are preformed so as to follow the outline of the outer casing, the first and second films are placed in a mold, and a transparent resin material is injected into a space between the first and second films, and molded. Thus, part of the outer casing is formed. 
     The surface panel according to Domestic Re-publication of PCT International Publication for Patent Application No. WO2008/149789 is advantageous in that the transmission quality of display light is favorable since a light transmissive region is formed by the glass substrate. However, since the surface panel includes the frame-shaped decorative portion made of a synthetic resin at the outer periphery of the glass substrate, the area of the light transmissive region and a sensing region, in which the touch sensor can perform sensing, is very small. Moreover, an injection molding has to be performed by positioning an assembly of the glass substrate and the touch sensor inside the mold. Thus, the method of manufacturing the surface panel is complex. 
     In the outer casing described in Japanese Unexamined Patent Application Publication No. 2009-130283, a touch sensor is disposed on a region that is different from a light transmissive portion. Thus, a user cannot perform an input operation by directly touching a display portion of the light transmissive portion with his/her finger. Moreover, since the light transmissive portion is disposed in a limited space on an upper side of the outer casing, a large screen cannot be displayed. 
     The method of manufacturing the surface panel according to Japanese Unexamined Patent Application Publication No. 2009-130283 involves two steps, which are a step of preforming the first and second films and a step of injecting a melted resin. Furthermore, the method is subject to limitation of accuracy of positioning the preformed first and second films inside the mold. 
     SUMMARY OF THE INVENTION 
     The present invention is made to solve the above existing problems and provides a surface panel that can secure a transmissive region and a sensing region in which a sensor performs sensing, as large as possible on a front surface of the panel. 
     The present invention provides a method of manufacturing a surface panel with which a surface panel having a large transmissive region and a large sensing region in which a sensor performs sensing can be formed, and with which a sensor film including an electrode layer and a wiring layer can be highly accurately positioned without being creased and thus can be integrated with a resin layer. 
     According to an aspect of the present invention, a surface panel includes a transmissive resin layer and a sensor film sensing the presence of a human finger in proximity thereto. The resin layer and the sensor film are stacked one on top of the other. The resin layer has a front surface and a back surface. The front surface includes a front-surface front portion, a front-surface right portion to the right of the front-surface front portion, and a front-surface left portion to the left of the front-surface front portion. The back surface includes a back-surface front portion to the back of the front-surface front portion, a back-surface right portion to the back of the front-surface right portion, and a back-surface left portion to the back of the front-surface left portion. The front-surface front portion is used as an operation face or a display face. The front-surface right portion and the front-surface left portion have such surface shapes as to extend from the front-surface front portion to the rear. The sensor film includes a transmissive electrode layer and a wiring layer connected to the electrode layer. The sensor film is fixed to the back surface of the resin layer, the electrode layer is positioned on the back-surface front portion of the resin layer, and the wiring layer is positioned on at least one of the back-surface right portion and the back-surface left portion of the resin layer. The sensor film includes a decorative portion covering the wiring layer on a side that is closer to a front surface of the sensor film than the wiring layer is. 
     In the surface panel according to the aspect of the present invention, the front-surface right portion and the front-surface left portion that are disposed on the right and left of the front-surface front portion used as an operation face or a display face have such surface shapes as to extend from the front-surface front portion to the rear and the wiring layer is disposed to the back of at least one of the front-surface right portion and the front-surface left portion. Thus, a wide region of the front-surface front portion can be used as the transmissive region for display and a sensor region in which a sensor performs sensing. 
     Since the electrode layer is positioned on the back-surface front portion, a large area of the front-surface front portion can be used as a region for sensing a finger. According to the aspect of the present invention, the electrode layer is positioned on the back-surface front portion. However, the present invention does not exclude a structure in which part of the electrode layer made of ITO or the like extends to the back-surface right portion and the back-surface left portion. In this structure, part of the transmissive region surrounded by the decorative portion extends to the back-surface right portion and the back-surface left portion. 
     According to the above aspect, the sensor film may include a window portion and the decorative portion on a front surface side thereof and the electrode layer and the wiring layer on a back surface side thereof, the decorative portion may have a shape of a frame surrounding the window portion, and the wiring layer may be positioned on a back surface of the decorative portion. The front surface of the sensor film may be closely attached to the back surface of the resin layer, the window portion may be positioned on the back-surface front portion, and the decorative portion may be positioned on the back-surface right portion and the back-surface left portion. 
     According to the above aspect, the electrode layer preferably is a transmissive conductive organic layer and the conductive organic layer is preferably extended to at least one of the back-surface right portion and the back-surface left portion. 
     The transmissive conductive organic layer has such a property as to follow the shape of the sensor film when the conductive organic layer is bent together with the sensor film. Thus, the conductive organic layer easily follows the bent shape of the back-surface front portion of the surface panel or the bent shape of the back-surface right portion and the back-surface left portion of the surface panel. 
     Consequently, the sensor region or the transmissive region can be brought to be as close as possible to the back-surface right portion and the back-surface left portion. Furthermore, part of the sensor region or the transmissive region can be extended to at least one of the back-surface right portion and the back-surface left portion. 
     According to another aspect of the present invention, provided is a method of manufacturing a surface panel including a transmissive resin layer and a sensor film stacked one on top of the other by using a first mold having a molding recessed portion and a second mold having a molding projecting portion, the sensor film sensing the presence of a human finger in proximity thereto. The method includes the steps of placing a sensor film prior to a molding process between the first mold and the second mold, the sensor film including a transmissive electrode layer and a wiring layer on a back surface side thereof and a decorative portion on a front surface side thereof, the wiring layer being connected to the electrode layer, the decorative portion covering the wiring layer, fitting the first mold and the second mold together and forming a cavity in which the sensor film is placed between the molding recessed portion and the molding projecting portion, and injecting a melted resin into the cavity to form a transmissive resin layer, forming a front-surface front portion, a front-surface right portion, and a front-surface left portion on the resin layer with the molding recessed portion, forming a back-surface front portion to the back of the front-surface front portion, a back-surface right portion to the back of the front-surface right portion, and a back-surface left portion to the back of the front-surface left portion with the molding projecting portion, closely attaching the sensor film to a back surface of the resin layer, positioning the electrode layer on the back-surface front portion, and positioning the wiring layer on at least one of the back-surface right portion and the back-surface left portion, the front-surface right portion and the front-surface left portion being located on the right and left of the front-surface front portion and having such surface shapes as to extend from the front-surface front portion to the rear. 
     With the method according to the above aspect, the sensor film can be closely attached to the resin layer with simple steps of placing a sensor film prior to a molding process in the molds and injecting a melted resin into the molds. The sensor film including the decorative portion and the electrode layer is closely attached to the back surface side of the molded surface panel, which has a recessed shape, and thus a sensor film is not exposed to the atmosphere through the front surface of the surface panel. Thus, the decorative portion does not come off or is not damaged even though a user touches the front surface of the surface panel with his/her finger. 
     With the method according to the above aspect, the sensor film may be pressed in the cavity against a front surface of the molding projecting portion by a pressure with which the melted resin is injected, and an outer peripheral portion of the sensor film positioned outside the cavity between the first mold and the second mold may be allowed to be elongated by the pressure and heat. 
     With the method according to the above aspect, the sensor film is not completely restrained between the first mold and the second mold and thus is allowed to be elongated between the first mold and the second mold. Thus, when the sensor film is pressed against the molding projecting portion of the second mold by the melted resin injected into the cavity, the sensor film is less likely to become creased. 
     With the method according to the above aspect, the cavity is preferably disposed such that a length direction of the cavity orthogonal to a direction in which the first mold and the second mold face each other coincides with a direction of gravity. A gate formed in the first mold is preferably positioned to be lower than a vertical middle point of the cavity. 
     When the cavity is vertically disposed and the gate is positioned at a lower portion of the first mold, the melted resin injected into the cavity gradually rises inside the cavity. Thus, the sensor film can be closely attached to a front surface of the molding projecting portion without being creased. 
     In the surface panel according to the present invention, a transmissive region that transmits a display content and a sensing region in which a sensor performs sensing can be made as large as possible. 
     With the method of manufacturing a surface panel according to the present invention, the sensor film can be attached to the back surface of the resin layer so as to follow the shape of the back surface by mainly two steps, which are a step of fitting molds together and a step of injecting a melted resin. With this method, the sensor film is less likely to become creased, and the sensor portion, the decorative portion, and the resin layer can be easily positioned with respect to one another. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view illustrating a surface panel according to an embodiment of the present invention; 
         FIG. 2  is a sectional view of the surface panel illustrated in  FIG. 1 , taken along the line II-II; 
         FIG. 3  is a sectional view of the surface panel illustrated in  FIG. 1 , taken along the line III-III. 
         FIG. 4  is a front view of the surface panel illustrated in  FIG. 1 ; 
         FIG. 5  is an enlarged view of part of the surface panel illustrated in  FIG. 3 ; 
         FIG. 6  is an exploded view illustrating the layered structure of a sensor film; 
         FIG. 7  is a perspective plan view of patterns of electrode layers and wiring layers on the back surface side of the sensor film; 
         FIG. 8  is a front view of a first mold seen from a molding side; 
         FIG. 9  is a sectional view of the first mold illustrated in  FIG. 8  and a second mold, taken along the line IX-IX; 
         FIG. 10  is a sectional view illustrating a state where a sensor film prior to a molding process is inserted in a cavity and molds are fitted together; 
         FIG. 11  is a sectional view illustrating a state where the molds are fitted together and a melted resin is injected into the cavity; 
         FIG. 12  is a front view of a molded product that is seen immediately after being removed from the second mold, in the arrow XII direction illustrated in  FIG. 11 ; 
         FIGS. 13A, 13B, and 13C  are enlarged views illustrating the state where a melted resin is injected into the cavity from a gate with a method of manufacturing a front surface plate according to an embodiment of the present invention; and 
         FIGS. 14A, 14B, and 14C  are enlarged views illustrating the state where a melted resin is injected into a cavity from a gate with a method of manufacturing a front surface plate according to a comparative example. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A surface panel  1  according to an embodiment is used as part of a casing of a mobile device, such as a mobile phone and a personal digital assistance. 
     As illustrated in  FIGS. 1 to 3 , a front surface  2  of the surface panel  1  has a projecting shape and a back surface  3  of the surface panel  1  has a recessed shape. The front surface  2  is disposed to the front of the casing of the mobile device (faces in the Z1 direction), and serves as an operation face or a display face. The back surface  3  faces rearward (in the Z2 direction), that is, toward the inside of the casing of the mobile device. 
     As illustrated in  FIGS. 2 and 3 , the surface panel  1  is formed by closely attaching a resin layer  4  and a sensor film  5  to each other. The resin layer  4  is seen on a side of the front surface  2  and the sensor film  5  is seen on a side of the back surface  3 . 
     The front surface  2  of the resin layer  4  has a wide front-surface front portion  2   a , which serves as a digitally operated operation face and a display face. The front-surface front portion  2   a  is substantially flat or has a curved shape so as to project to the front (in the Z1 direction). 
     A front-surface upper portion  2   b  is formed at a lengthwise upper end portion (an end portion in the Y1 direction) of the resin layer  4  and a front-surface lower portion  2   c  is formed at a lengthwise lower end portion (an end portion in the Y2 direction) of the resin layer  4 . The front-surface upper portion  2   b  and the front-surface lower portion  2   c  have such surface shapes as to extend from the front-surface front portion  2   a  to the rear (in the Z2 direction). A front-surface right portion  2   d  is formed at a right end portion (an end portion in the X1 direction) of the resin layer  4  and a front-surface left portion  2   e  is formed at a left end portion (an end portion in the X2 direction) of the resin layer  4 . The front-surface right portion  2   d  and the front-surface left portion  2   e  have such surface shapes as to extend from the front-surface front portion  2   a  to the rear. 
     The back surface  3  of the resin layer  4  includes a back-surface front portion  3   a  to the back of the front-surface front portion  2   a , an back-surface upper portion  3   b  to the back of the front-surface upper portion  2   b , a back-surface lower portion  3   c  to the back of the front-surface lower portion  2   c , a back-surface right portion  3   d  to the back of the front-surface right portion  2   d , and a back-surface left portion  3   e  to the back of the front-surface left portion  2   e.    
     In the resin layer  4 , a boundary between the front-surface front portion  2   a  and the front-surface upper portion  2   b  or the front-surface lower portion  2   c  and a boundary between the front-surface front portion  2   a  and the front-surface right portion  2   d  or the front-surface left portion  2   e  are disposed at positions at which the resin layer  4  has a front surface curvature or a front surface angle that is different from that of the front-surface front portion  2   a . Likewise, a boundary between the back-surface front portion  3   a  and the back-surface upper portion  3   b  or the back-surface lower portion  3   c  and a boundary between the back-surface front portion  3   a  and the back-surface right portion  3   d  or the back-surface left portion  3   e  are disposed at positions at which the resin layer  4  has a front surface curvature or a front surface angle that is different from that of the back-surface front portion  3   a.    
       FIG. 5 , which is an enlarged view of part of the surface panel  1 , illustrates a boundary B 2  between the front-surface front portion  2   a  and the front-surface right portion  2   d  and a boundary B 3  between the back-surface front portion  3   a  and the back-surface right portion  3   d , which are defined on the basis of the above definition. 
     The resin layer  4  is made of a transmissive synthetic resin material such as an acrylic material, for example, polymethyl methacrylate (PMMA). 
     As illustrated in  FIG. 5  and  FIG. 6  (an exploded view illustrating the layered structure of the sensor film), a sensor film  5  includes a transmissive base film  5   a , a decorative portion  6  formed on the front surface of the base film  5   a , and a touch sensor portion  30  formed on the back surface of the base film  5   a . The base film  5   a  of the sensor film  5  is a transmissive synthetic resin film. The base film  5   a  is made of polyethylene terephthalate (PET), which is a synthetic resin having a strength and heat resistance appropriate for forming the touch sensor portion  30 . Cyclic polyolefin (COP) or the like can be employed, instead. 
     Herein, a material that is transmissive preferably means that the material has a total light transmittance of 90% or more, that is, the material is transparent. However, the total light transmittance may be lower than 90% as long as the material can transmit light therethrough, for example, the total light transmittance may be 60% or more. 
     As illustrated in  FIGS. 1 and 4 , the decorative portion  6  formed on the front surface side of the sensor film  5  can be visually seen through the resin layer  4  from the front (in the Z1 direction). The decorative portion  6  has a hue based on a design of the surface panel  1  and has a frame shape. A region surrounded by the frame-shaped decorative portion  6  is a transmissive region  7 . In the surface panel  1  illustrated in  FIGS. 1 and 4 , the transmissive region  7  is rectangular. The transmissive region  7  is positioned in a region of the back-surface front portion  3   a  of the resin layer  4 . As illustrated in  FIG. 5 , a right edge portion  7   a  of the transmissive region  7  is positioned near the border B 3  between the back-surface front portion  3   a  and the back-surface right portion  3   d . A left edge portion  7   b  of the transmissive region  7  is positioned likewise. 
     As illustrated in  FIGS. 4 and 5 , the touch sensor portion  30  of the sensor film  5  includes multiple electrode layers  31 , multiple right wiring layers  32   a  connected to the right of the electrode layers  31 , and multiple left wiring layers  32   b  connected to the left of the electrode layers  31 . 
     As illustrated in  FIG. 4  and  FIG. 7  (a perspective plan view of patterns of the electrode layers  31  on the back surface side of the sensor film  5 , seen from the front surface side), the electrode layers  31  are disposed in the transmissive region  7  surrounded by the frame-shaped decorative portion  6 , and the right wiring layers  32   a  and the left wiring layers  32   b  are disposed at a back side of the decorative portion  6  so as to be hidden by the decorative portion  6 . 
     Multiple pairs of right electrodes  31   a  and left electrodes  31   b , each pair forming one electrode layer  31 , are arranged side by side in the length direction (Y1-Y2 direction). The electrode layers  31  are made of indium tin oxide (ITO). The electrode layers  31  are formed by being deposited on the back surface of the base film  5   a  made of PET or the like, and then etching into the shapes of the right electrodes  31   a  and the left electrodes  31   b.    
     The right wiring layers  32   a  are connected to the right electrodes  31   a  and the left wiring layers  32   b  are connected to the left electrodes  31   b . The right wiring layers  32   a  and the left wiring layers  32   b  are conductive organic layers made of a binder resin containing a low-resistive conductor, such as silver paste, gold paste, or carbon paste. The conductive organic layers that the right and left wiring layers  32   a  and  32   b  are made of are more flexible than ITO that the electrode layers  31  are made of. Specifically, the conductive organic layers exhibit a higher elongation and curvature than ITO under the same load. 
     The right wiring layers  32   a  and the left wiring layers  32   b  are formed by depositing a conductive organic layer on an ITO layer on the back surface of the base film  5   a  and then forming patterns for the electrode layers  31 , the right wiring layers  32   a , and the left wiring layers  32   b  by etching. Thereafter, part of the conductive organic layer deposited on the front surface of the electrode layers  31  is removed by etching. Alternatively, the right wiring layers  32   a  and the left wiring layers  32   b  may be formed by a printing process. 
     As illustrated in  FIG. 5 , the sensor film  5  is bent so as to follow the shape of part of the resin layer  4  from the back-surface front portion  3   a  to the back-surface right portion  3   d  and is closely attached to the resin layer  4 . The electrode layers  31  made of ITO are disposed within a region of the back-surface front portion  3   a  and thus are not greatly curved. On the other hand, a portion of the sensor film  5  that extends beyond, in the X1 direction, a region in which the electrode layers  31  are disposed is bent at a large curvature and the most part of the portion of the sensor film  5  is in close contact with the back-surface right portion  3   d . The front side of the right wiring layers  32   a  is covered by the decorative portion  6 . The left wiring layers  32   b  are covered likewise. 
     A portion of the sensor film  5  in which the right and left wiring layers  32   a  and  32   b  formed of the conductive organic layer are disposed is more easily bent than the region in which the electrode layers  31  made of ITO are disposed. The right and left wiring layers  32   a  and  32   b  easily follow flexure and are less likely to be damaged due to the flexure. For this reason, a portion of the sensor film  5  including at least part of the right wiring layers  32   a  or the left wiring layers  32   b  can be closely attached to the corresponding one of the back-surface right portion  3   d  and the back-surface left portion  3   e . Alternatively, a portion of the sensor film  5  including all the right wiring layers  32   a  or the left wiring layers  32   b  can be closely attached to the corresponding one of the back-surface right portion  3   d  and the back-surface left portion  3   e.    
     When at least part of the right wiring layers  32   a  or the left wiring layers  32   b  are disposed on the corresponding one of the back-surface right portion  3   d  and the back-surface left portion  3   e , the area of the electrode layers  31  disposed on the back-surface front portion  3   a  can be increased. Consequently, it is possible to widen the transmissive region  7  and to bring the right edge portion  7   a  and the left edge portion  7   b  of the transmissive region  7  to be closer to the border B 3  between the back-surface front portion  3   a  and the back-surface right portion  3   d  and a border between the back-surface front portion  3   a  and the back-surface left portion  3   e . Furthermore, the right edge portion  7   a  and the left edge portion  7   b  of the transmissive region  7  can be positioned in a region on the back-surface right portion  3   d  and the back-surface left portion  3   e  beyond the border B 3  and the border between the back-surface front portion  3   a  and the back-surface left portion  3   e.    
     A mobile device employing the surface panel  1  includes a display device, such as a liquid crystal display panel, inside the casing, and a display screen of the display device faces the inner side of the transmissive region  7 . When a user uses the mobile device, the user can see the display screen through the transmissive resin layer  4  and the base film  5   a  in the transmissive region  7 . When the user touches, with his/her finger, the front-surface front portion  2   a  of the resin layer  4  in the transmissive region  7  through which the display screen can be seen, the touch sensor portion  30  changes its output in accordance with the capacitance between the finger and the corresponding one of the electrode layers  31 , and thus can sense the point of the transmissive region  7  that is touched with the finger. 
     Since the transmissive region  7  in the surface panel  1  can be widened as much as possible within the region of the back-surface front portion  3   a , the display area of the display screen and the area of the digitally operated operation region can be increased, accordingly. 
     As illustrated in  FIG. 4 , the right wiring layers  32   a  and the left wiring layers  32   b  are formed on the back surface of the base film  5   a  and extended in the Y2 direction. Part of the base film  5   a  is extended outward beyond the back-surface lower portion  3   c  and serves as a cable piece for wiring, and a land portion at a leading end of the cable piece can be connected to a connector mounted in the casing. 
     As illustrated in  FIGS. 1 and 2 , the surface panel  1  includes a first opening  8  and a second opening  9 . The first opening  8  is disposed at a position that is lower (at a side in the Y2 direction) than a middle point of the surface panel  1  in the length direction (Y direction). The second opening  9  is disposed at a position that is higher (at a side in the Y1 direction) than the middle point. The first opening  8  and the second opening  9  penetrate through the resin layer  4  and the sensor film  5 . 
     A microphone and a speaker are disposed inside the casing at such positions as to face the first opening  8  and the second opening  9 . Thus, a sound corresponding to a speech operation, which is performed as a mobile phone, or a sound corresponding to an image displayed on the display screen can be output through the openings  8  and  9 . 
     Now, a method of manufacturing the surface panel  1  will be described. 
       FIG. 8  illustrates a first mold  10  and  FIG. 9  illustrates the first mold  10  and a second mold  20 . The Y1-Y2 direction illustrated in  FIGS. 8 and 9  and the X1-X2 direction illustrated in  FIG. 8  correspond to the length direction (Y1-Y2 direction) and the width direction (X1-X2 direction) of the surface panel  1  to be formed. The first mold  10  and the second mold  20  are longitudinally placed such that the Y2 direction coincides with the direction of gravity (G direction). 
     The first mold  10  has an opposing flat face  11  that extends in the Y1-Y2 direction and that has a molding recessed portion  12  in a middle portion thereof. As illustrated in  FIGS. 8 and 9 , in the molding recessed portion  12 , a bottom surface serves as a center-surface molding portion  12   a  for forming the front-surface front portion  2   a  of the resin layer  4 , an end surface in the Y1 direction serves as an upper-surface molding portion  12   b  for forming the front-surface upper portion  2   b , an end surface in the Y2 direction serves as a lower-surface molding portion  12   c  for forming the front-surface lower portion  2   c , an end surface in the X1 direction serves as a right-surface molding portion  12   d  for forming the front-surface right portion  2   d , and an end surface in the X2 direction serves as a left-surface molding portion  12   e  for forming the front-surface left portion  2   e.    
     In the center-surface molding portion  12   a , a rectangular first step portion  18  that corresponds to the first opening  8  is formed at a side in the Y2 direction, and a rectangular second step portion  19  that corresponds to the second opening  9  is formed at a side in the Y1 direction. 
     The first mold  10  has a gate (sprue gate)  13  and an opening end  13   a  of the gate  13  is open to the inside of the molding recessed portion  12  within a region of the first step portion  18 .  FIG. 9  illustrates a center O of the molding recessed portion  12  in the Y1-Y2 direction. The center O is a middle point between the upper-surface molding portion  12   b  and the lower-surface molding portion  12   c . The gate  13  is positioned to be lower than the center O (at a side in the Y2 direction), and to be at a side in the Y2 direction with respect to a middle point between the center O and the lower-surface molding portion  12   c.    
     As illustrated in  FIGS. 8 and 9 , the first mold  10  has a relief recess  14  at a side that is farther in the Y1 direction than the molding recessed portion  12 . Multiple air-exit paths  15  are formed between the upper-surface molding portion  12   b  of the molding recessed portion  12  and the relief recess  14 . The air-exit paths  15  are shallow grooves that are slightly recessed from the opposing flat face  11 . 
     As illustrated in  FIG. 8 , clearance holes  16  are formed at four positions outside the molding recessed portion  12 . 
     As illustrated in  FIG. 9 , the second mold  20  has an opposing flat face  21  that extends in the Y1-Y2 direction, and a molding projecting portion  23  that projects toward the first mold  10  is integrally formed in a center portion of the opposing flat face  21 . In the molding projecting portion  23 , a top portion serves as a center-back-surface molding portion  23   a  for forming the back-surface front portion  3   a  of the surface panel  1 , an end surface in the Y1 direction serves as an upper-back-surface molding portion  23   b  for forming the back-surface upper portion  3   b , and an end surface in the Y2 direction serves as a lower-back-surface molding portion  23   c  for forming the back-surface lower portion  3   c . The molding projecting portion  23  also has a right-back-surface molding portion for forming the back-surface right portion  3   d  and a left-back-surface molding portion for forming the back-surface left portion  3   e , which are not illustrated. 
     As illustrated in  FIG. 9 , a first release pin  24  and a second release pin  25  are mounted on the second mold  20  so as to be movable forward and backward. The first release pin  24  is disposed at such a position as to face the first step portion  18  of the first mold  10 , and the second release pin  25  is disposed at such a position as to face the second step portion  19 . 
     Positioning pins  26  are fixed to the second mold  20  at four positions outside the molding projecting portion  23 . Each positioning pin  26  vertically projects from the opposing flat face  21 . When the first mold  10  and the second mold  20  are fitted together, the positioning pins  26  are inserted into the clearance holes  16  of the first mold  10 . 
     The positions of the positioning pins  26  and the positions of the clearance holes  16  correspond to each other. As illustrated in  FIG. 8 , the four positioning pins  26  are positioned equidistantly from the center O of the molding recessed portion  12 . The center O is positioned at a point at which the molding recessed portion  12  is halved in the length direction (Y1-Y2 direction) and in the width direction (X1-X2 direction). The positioning pins  26  are positioned equidistantly from the center O and equiangularly (at an angle θ) with respect to a center line O 1  that passes the center O and that extends in the longitudinal direction. 
     Note that all the positions of the positioning pin  26  and the clearance holes  16  do not have to be equidistant from the center O depending on the shape of the surface panel  1  to be formed, i.e., the shape of the molding recessed portion  12  and the molding projecting portion  23 . For example, a positioning pin  26  at a side in the Y1 direction may be farther from the center O in the Y direction than a positioning pin  26  at a side in the Y2 direction. Here, it is preferable that an interval in the X direction between the two positioning pins  26  at a side in the Y1 direction be equal to an interval in the X direction between the two positioning pins  26  at a side in the Y2 direction. 
     As illustrated in  FIG. 9 , gap forming portions  27  project at multiple positions on the opposing flat face  21  of the second mold  20 . As illustrated in  FIG. 10 , when the first mold  10  and the second mold  20  are fitted together, the gap forming portions  27  come into contact with the opposing flat face  11  of the first mold  10 . Thus, an opposing gap T between the opposing flat face  11  of the first mold  10  and the opposing flat face  21  of the second mold  20  is defined. The opposing gap T has a thickness that is substantially equal to or slightly larger than the thickness of the sensor film  5 . To be more specific, the thickness of the opposing gap T is not set such that the sensor film  5  is firmly nipped in the opposing gap T and is set such that the sensor film  5  can be elongated inside the opposing gap T when a stress is caused in the sensor film  5  due to the pressure from the melted resin. 
     The gap forming portions  27  may be formed on the opposing flat face  11  of the first mold  10 , or both of the opposing flat face  11  and the opposing flat face  21 . 
       FIG. 6  is an exploded perspective view illustrating the structure of a sensor film  5  prior to a molding process, and  FIG. 7  is a perspective view of the sensor film  5  seen from the front. 
     In the sensor film  5 , the frame-shaped decorative portion  6  is attached to the front surface of the base film  5   a  around a window portion  7   c  formed for forming the transmissive region  7  of the surface panel  1 . The base film  5   a  has a thickness on the order of 0.05 to 0.5 mm. The decorative portion  6  is formed on the front surface of the base film  5   a  by coating. The decorative portion  6  is colored with a hue that expresses the appearance of the casing of an electronic device, and is formed of multiple coated color films. If a protective film having a separator function is stacked on the base film  5   a , the thickness can be reduced to be lower than 0.05 mm. 
     The electrode layers  31 , the right wiring layers  32   a , and the left wiring layers  32   b  are formed on the back surface of the base film  5   a . Each electrode layer  31  is formed by etching an ITO film so as to be divided into the right electrode  31   a  and the left electrode  31   b . The right wiring layers  32   a  and the left wiring layers  32   b  are the conductive organic layers and are formed by etching, or may be formed by printing. 
     The untreated sensor film  5  is rectangular and has the positioning holes  5   b  at four corners. 
     As illustrated in  FIG. 9 , the sensor film  5  is mounted on the second mold  20  while the first mold  10  and the second mold  20  are being separated. The positioning pins  26  are inserted into the positioning holes  5   b  illustrated in  FIGS. 6 and 7 , and thus the sensor film  5  is positioned with respect to the second mold  20 . The sensor film  5  is placed such that the front surface having the decorative portion  6  faces the first mold  10 . The first mold  10  and the second mold  20  have been subjected to preheating in advance. The preheating temperature is higher than the room temperature but lower than the glass transition temperature of the base film  5   a  of the sensor film  5 , for example, in a range of around 60 to 100° C. 
     As illustrated in  FIG. 10 , when the first mold  10  and the second mold  20  are fitted together, the positioning pins  26  projecting from the second mold  20  enter the inside of the clearance holes  16  of the first mold  10 . Thus, the gap forming portions  27  of the second mold  20  come into contact with the opposing flat face  11  of the first mold  10  and the opposing gap T is defined as being between the opposing flat face  11  of the first mold  10  and the opposing flat face  21  of the second mold  20 . Here, a cavity C is also defined as being between the molding recessed portion  12  of the first mold  10  and the molding projecting portion  23  of the second mold  20 . 
     As illustrated in  FIG. 10 , when the first mold  10  and the second mold  20  are fitted together, the sensor film  5  that is positioned using the positioning pins  26  is placed in the cavity C while a small amount of tension is applied to the sensor film  5  by the pressure of the molding projecting portion  23 . An outer peripheral portion of the sensor film  5  is placed in the opposing gap T between the first mold  10  and the second mold  20 . 
     Subsequently, as illustrated in  FIG. 11 , a melted resin  4   a  made of, for example, PMMA is injected into the cavity C from the gate  13  of the first mold  10 . 
     When the preheated sensor film  5  comes into contact with the melted resin  4   a , the sensor film  5  is heated to a temperature that is almost the glass transition temperature to be softened and is pressed against the front surface of the molding projecting portion  23  by the injection pressure of the melted resin  4   a . The sensor film  5  that is pressed against the front surface of the molding projecting portion  23  is likely to elongate in the plane direction. Here, since the sensor film  5  is not restrained inside the opposing gap T, the sensor film  5  easily elongates toward the outer periphery thereof. In this manner, the sensor film  5  that is pressed against the front surface of the molding projecting portion  23  can elongate relatively freely inside the cavity C and thus is less likely to become creased. 
     By injecting the melted resin  4   a  into the cavity C, the shapes of the front surface  2  and the back surface  3  of the resin layer  4  are determined by the melted resin  4   a  and the sensor film  5 . Furthermore, as illustrated in  FIG. 12 , the outer peripheral portion of the sensor film  5  that overruns the cavity C expands in the Y1, Y2, X1, and X2 directions. Here, since the base film  5   a  of the sensor film  5  is softened, the positioning holes  5   b  expand radially. 
     As illustrated in  FIG. 12 , the outer peripheral portion of the sensor film  5  is supported by the four positioning pins  26  with a uniform force in the corresponding directions when the outer peripheral portion expands in the Y1, Y2, X1, and X2 directions. Thus, the window portion  7   c  and the touch sensor portion  30  formed in the sensor film  5  can be kept being positioned in the center portion of the cavity C. As illustrated in  FIG. 1 , the transmissive region  7  and the touch sensor portion  30  are more likely to be positioned uniformly in the molded surface panel  1  with respect to the front-surface front portion  2   a . It is preferable that the shape or size of the window portion  7   c  at the center of the decorative portion  6  and the shape or size of the electrode layers  31 , the right wiring layers  32   a , and left wiring layers  32   b , be preset in consideration of probable elongation of the sensor film  5  at the time of injecting the melted resin. 
     The first mold  10  and the second mold  20  are vertically placed in line with the direction of gravity (G direction). Since the gate  13  is positioned to be sufficiently lower than the center O of the cavity C, the sensor film  5  is prevented from being creased. 
     As illustrated in  FIG. 13A , in the stage where the first mold  10  and the second mold  20  are fitted together, the sensor film  5  crosses the inside of the cavity C between the lower-surface molding portion  12   c  and the lower-back-surface molding portion  23   c . As illustrated in  FIG. 13B , when the melted resin  4   a  is injected into the cavity C from the gate  13 , the melted resin  4   a  flows down into a space between the lower-surface molding portion  12   c  and the lower-back-surface molding portion  23   c  according to the gravity, and the sensor film  5  is thus pressed against and along the front surface of the lower-back-surface molding portion  23   c  by the flow in the F1 direction. Since the gate  13  is positioned at a lower position, the flow of the melted resin  4   a  in the F1 direction is less likely to be disturbed. Thus, the sensor film  5  is closely attached to the lower-back-surface molding portion  23   c  without being creased. 
     As illustrated in  FIG. 13C , when a lower portion of the cavity C is filled with the melted resin  4   a  and the sensor film  5  is closely attached to the lower-back-surface molding portion  23   c , the melted resin  4   a  gradually rises in the Y1 direction. At this time, the sensor film  5  is upwardly attached to the center-back-surface molding portion  23   a  of the molding projecting portion  23  by the force of the flow of the melted resin  4   a  in the F2 direction. 
     While the melted resin  4   a  is rising in the cavity C, the air in the cavity C is output to the inside of the relief recess  14  through the air-exit paths  15  formed at an upper end portion of the molding recessed portion  12  of the first mold  10 . 
     Since the sensor film  5  behaves in the above-described manner in the cavity C, the sensor film  5  is less likely to become creased and more likely to be closely attached to the front surface of the molding projecting portion  23 . 
       FIGS. 14A to 14C  illustrate a molding operation according to a comparative example in which a gate  13 A is positioned to be close to an edge portion of the lower-surface molding portion  12   c  of the first mold  10 . As illustrated in  FIG. 14B , since the melted resin  4   a  that is injected into the cavity C from the gate  13 A flows obliquely upward, or in the F3 direction, the sensor film  5  is more likely to become creased. As illustrated in  FIG. 14C , the melted resin  4   a  that thereafter flows in the F4 direction lifts up the creased portion of the sensor film  5 . Thus, the crease is highly likely to remain unsolved. 
     For this reason, a gate should be not disposed at a portion of the first mold  10  that faces a range from the opposing flat face  21  of the second mold  20  to a half point (H/2) at which the height H of the lower-back-surface molding portion  23   c  is halved. 
     After the melted resin  4   a  is fed to the cavity C and cooled down, the first mold  10  and the second mold  20  are detached from each other. By projecting the first release pin  24  and the second release pin  25  of the second mold  20 , a molded product is detached from the molding projecting portion  23  of the second mold  20 . 
     As illustrated in  FIG. 12 , the molded product removed from the molds  10  and  20  has a gate imprint  13   b  and an imprint of the first release pin  24  at a thin portion  18   a  that is formed by the first step portion  18  of the first mold  10 . The molded product also has an imprint of the second release pin  25  at a thin portion  19   a  formed by the second step portion  19 . The gate imprint  13   b  and the other imprints can be removed by forming the first opening  8  and the second opening  9  by punching out part of the resin layer  4  and the sensor film  5  at the thin portions  18   a  and  19   a . The surface panel  1  is formed by further cutting part of the resin layer  4  and the sensor film  5  that overruns the cavity C. 
     In this embodiment, the transmissive electrode layer  31  is made of ITO. However, the electrode layer  31  may be formed of a transmissive conductive organic film made of, for example, polyethylenedioxythiophene (PEDOT). The conductive organic film is more flexible than ITO. Thus, the electrode layer  31  formed of the conductive organic film can be expanded beyond the border B 3  to the region of the back-surface right portion  3   d  in the sectional view of  FIG. 5 . Accordingly, the right edge portion  7   a  and the left edge portion  7   b  of the transmissive region  7  can be made closer to or can be positioned on the back-surface right portion  3   d  and the back-surface left portion  3   e , and thus a region in which the transmissive region  7  and the touch sensor portion  30  are formed can be further widened 
     The method of manufacturing the surface panel  1  according to the present invention is not limited to the one according to the embodiment. For example, the sensor film  5  may be preformed so as to follow the shape of the back surface  3  of the resin layer  4  by compressed-air molding or vacuum molding, the preformed sensor film  5  may be inserted into a space between the molds, and then the melted resin  4   a  may be injected into the space. 
     The surface panel according to the present invention is not limited to being used as a casing of a mobile device according to the embodiment, and may be used as part of a remote controller for controlling electric products or a casing of other electronic devices.

Technology Category: 3