Patent Publication Number: US-2015070598-A1

Title: Cover window, manufacturing method thereof, and touchscreen including the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of Korean Patent Application No. 10-2013-0107547 filed on Sep. 6, 2013, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a cover window, a manufacturing method thereof, and a touchscreen including the same. 
     2. Description of the Related Art 
     A touch sensing apparatus such as a touchscreen, a touch pad, or the like, an input apparatus attached to a display apparatus to provide an intuitive data input method to a user, has recently been widely used in various electronic devices such as cellular phones, personal digital assistants (PDA), navigation devices, and the like. Particularly, as demand for smartphones has recently increased, the use of touchscreens capable of providing various data input methods in a limited form factor has continually increased. 
     Touchscreens used in portable devices may be mainly divided into resistive type touchscreens and capacitive type touchscreens, according to a method of sensing a touch input. Among them, capacitive type touchscreens have advantages in that they have a relatively long lifespan and may easily allow for the implementation of various data input methods and gestures, such that the use thereof has correspondingly increased. Particularly, capacitive type touchscreens may more easily allow for the implementation of a multi-touch interface, as compared with resistive type touchscreens, such that they are widely used in devices such as smartphones, and the like. 
     Capacitive type touchscreens include a plurality of electrodes having a predetermined pattern and defining a plurality of nodes in which changes in capacitance are generated by a touch input. In the plurality of nodes distributed on a two-dimensional plane, changes in self-capacitance or mutual-capacitance change are generated by touches. Coordinates of touches may be calculated by applying a weighted average method, or the like, to the changes in capacitance generated in the plurality of nodes. 
     A touchscreen used in the touchscreen is divided into an active region for receiving touches by a user and a bezel region for visually shielding wiring electrodes, or the like, wherein the bezel region is formed by depositing a predetermined printed region on a cover window to which touches is applied. However, in the case in which the predetermined printing region is deposited on the cover window, a step portion may be generated, such that air bubbles may be generated in an adhesive layer adhered to the cover window and an electrode formed on the cover window may be short-circuited. 
     The following Related Art Document (Patent Document 1), which relates to a touchscreen and a manufacturing method thereof, discloses content in which a cover lens is partially etched and a decoration region is formed in the etched region in order to remove a step portion due to the decoration region formed in a cover lens, but does not disclose content in which a step portion, formed due to an error inevitably caused by a manufacturing process is removed. 
     RELATED ART DOCUMENT 
     
         
         (Patent Document 1) Korean Patent Laid-Open Publication No. 10-2013-0061252A 
       
    
     SUMMARY OF THE INVENTION 
     An aspect of the present invention provides a cover window in which a step portion due to an error inevitably caused by a manufacturing process is removed by burying a printing region in one surface of one glass substrate and bonding one surfaces of one glass substrate and another glass substrate to each other, a manufacturing method thereof, and a touchscreen including the same. 
     According to an aspect of the present invention, there is provided a cover window including: a first glass panel; a printed portion formed in a concave part of one surface of the first glass panel; and a second glass panel bonded to one surface of the first glass panel. 
     The concave part and the printed portion may have the same thickness as each other. 
     One surfaces of the first glass panel and the second glass panel may be thermal-fusion-bonded to each other. 
     One surfaces of the first glass panel and the second glass panel may be thermal-fusion-bonded to each other at a temperature of 550° C. 
     One surfaces of the first glass panel and the second glass panel may be double-side-bonded to each other using an anti-scattering film. 
     The concave part may be formed by etching one surface of the first glass panel according to a predetermined mask pattern. 
     The concave part may be formed by etching one surface of the first glass panel with a hydrofluoric acid aqueous solution. 
     The cover window may further include a reinforcing layer formed by subjecting surfaces of the first and second glass panels bonded to each other to a chemical reinforcing treatment. 
     The reinforcing layer may be formed by subjecting the surfaces of the first and second glass panels bonded to each other to the chemical reinforcing treatment using KNO 3  at a temperature of 550° C. 
     According to another aspect of the present invention, there is provided a touchscreen including: a substrate; a plurality of electrodes formed on one surface or both surfaces of the substrate; and the cover window as described above bonded to any one surface of the substrate on which the plurality of electrodes are formed and a surface facing the any one surface of the substrate. 
     According to another aspect of the present invention, there is provided a touchscreen including: the cover window as described above; a plurality of first electrodes formed on the cover window; and a plurality of second electrodes insulated from the plurality of first electrodes. 
     According to another aspect of the present invention, there is provided a manufacturing method of a cover window, including: forming a concave part having a predetermined thickness in one surface of a first glass panel; forming a predetermined printed portion in the concave part; and bonding one surfaces of the first glass panel and a second glass panel to each other. 
     The forming of the concave part may include: depositing a predetermined photo-resist on the first glass panel; exposing a predetermined region of the photo-resist to form a mask pattern; and etching the first glass panel according to the mask pattern. 
     In the etching of the first glass panel, the first glass panel may be etched using a hydrofluoric acid aqueous solution. 
     In the forming of the predetermined printed portion, the predetermined printed portion may be formed in the concave part using a screen printing method or an inkjet printing method. 
     In the bonding of the one surfaces of the first glass panel and the second glass panel to each other, one surfaces of the first glass panel and the second glass panel may be thermal-fusion-bonded to each other. 
     One surfaces of the first glass panel and the second glass panel may be thermal-fusion-bonded to each other at a temperature of 550° C. 
     In the bonding of the one surfaces of the first glass panel and the second glass panel to each other, one surfaces of the first glass panel and the second glass panel may be double-side-bonded to each other using an anti-scattering film. 
     The manufacturing method of a cover window may further include subjecting surfaces of the first and second glass panels bonded to each other to a chemical reinforcing treatment. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a perspective view showing an appearance of an electronic device including a touchscreen according to an embodiment of the present invention; 
         FIG. 2  is a front view of the touchscreen according to the embodiment of the present invention; 
         FIGS. 3 through 6  are cross-sectional views of touchscreens according to various embodiments of the present invention; 
         FIGS. 7 and 8  are views showing a cover window according to the embodiment of the present invention; and 
         FIGS. 9A through 9G  are views showing a manufacturing process of the cover window according to the embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the shapes and dimensions of elements may be exaggerated for clarity, and the same reference numerals will be used throughout to designate the same or like elements. 
       FIG. 1  is a perspective view showing an appearance of an electronic device including a touchscreen according to an embodiment of the present invention. 
     Referring to  FIG. 1 , the electronic device  10  according to the present embodiment may include a display apparatus  11  for outputting an image, an input unit  12 , an audio unit  13  for audio output, and a touchscreen apparatus integrated with the display apparatus  11 , wherein the touchscreen apparatus may include a touchscreen. 
     As shown in  FIG. 1 , in the case of a mobile device, the touchscreen apparatus may be generally provided in the state in which it is integrated with the display apparatus and needs to have light transmissivity high enough to transmit a screen displayed by the display apparatus. Therefore, the touchscreen apparatus may be implemented by forming an electrode on a transparent substrate using a material having electrical conductivity. A wiring electrode connected to the electrode formed using the conductive material may be disposed in a bezel region of the display apparatus and be visually shielded by the bezel region. 
     Since it is assumed that the touchscreen apparatus is operated in a capacitive scheme, the touchscreen apparatus may include a plurality of electrodes having a predetermined pattern. In addition, the touchscreen apparatus may include a capacitance sensing circuit detecting changes in capacitance generated in the plurality of electrodes, an analog-to-digital converting circuit converting an output signal of the capacitance sensing circuit into a digital value, a calculating circuit judging a touch input using the data converted into the digital value, and the like. 
       FIG. 2  is a front view of the touchscreen according to the embodiment of the present invention; and  FIGS. 3 through 6  are cross-sectional views of touchscreens according to various embodiments of the present invention. 
     Referring to  FIGS. 2 through 5 , the touchscreen  200  according to the present embodiment may include a substrate  210 , a plurality of electrodes  220  and  230  provided on the substrate  210 , and a cover window  100  attached to a front surface of the substrate  210 . Here, an adhesive layer  250  adhering the substrate  210  and the cover window  100  to each other may be formed of an optical clear adhesive (OCA), but is not limited thereto. 
     Each of the plurality of electrodes  220  and  230  may be electrically connected to wiring electrodes  240  of a flexible circuit board  260  attached to one end of the substrate  210  through wirings and bonding pads. The flexible circuit board  260  may have a controller integrated circuit  270  mounted thereon to detect sensing signals generated in the plurality of electrodes  220  and  230  and judge touch inputs from the sensing signals. 
     The substrate  210  may be a transparent substrate on which the plurality of electrodes  220  and  230  are to be formed. Therefore, the substrate  210  may be formed of a material such as a polyethylene terephthalate (PET) film, a polycarbonate (PC) film, a polyethersulfone (PES) film, a polyimide (PI) film, a polymethlymethacrylate (PMMA) film, a cyclo-olefin polymer (COP) film, soda glass, or tempered glass. 
     The plurality of electrodes  220  and  230  may be formed on one surface or both surfaces of the substrate  210 . Although the plurality of electrodes  220  and  230  are shown as having rhomboid or diamond shaped patterns in  FIG. 2 , they may have various polygonal patterns such as rectangular patterns, triangular patterns, or the like. The plurality of electrodes  220  and  230  having conductivity may be formed of a material such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), carbon nanotubes (CNT), or a graphene and be formed by implementing invisible conductive fine lines using any one of Ag, Al, Cr, Ni, Mo, and Cu, or alloys thereof. 
     The plurality of electrodes  220  and  230  may include first electrodes  220  extended in an X axis direction and second electrodes  230  extended in a Y axis direction. In the case in which the first and second electrodes  220  and  230  are provided on both surfaces of the substrate  210  (See  FIG. 3 ) or both of the first and second electrodes  220  and  230  are provided on different substrates  210  (See  FIGS. 4 and 5 ), a predetermined insulating layer may be partially formed at intersection points between the first and second electrodes  220  and  230 . Unlike this, the first and second electrodes  220  and  230  may be provided and intersect with each other on different substrates  210 . 
     An apparatus electrically connected to the plurality of electrodes  220  and  230  to sense touches may detect the changes in capacitance generated in the plurality of electrodes  220  and  230  by touches and sense touches from the detected changes in capacitance. The first electrodes may be connected to channels defined as D 1  to D 8  in the controller integrated circuit to receive predetermined driving signals, and channels defined as S 1  to S 8  may be connected to the second electrodes  230  and be used to detect the changes in capacitance generated between the first and second electrodes  220  and  230 . Here, the controller integrated circuit  270  may judge touches using the changes in capacitance as a sensing signal. 
     Unlike the embodiment described above with reference to  FIGS. 3 through 5 , the plurality of electrodes  220  and  230  may be provided on the cover window  100 . Here, in the case in which the plurality of electrodes  220  and  230  are provided on one surface of the cover window  100 , a predetermined insulating layer may be partially formed at intersection points between the first and second electrodes  220  and  230 . 
     In addition, as shown in  FIG. 6 , a predetermined insulating layer  215  may cover the second electrode  230 , and the first electrodes  220  may be provided on one surface of the insulating layer  215 . The insulating layer  215  may be formed of an inorganic material including one of SiO 2 , Al 2 O 3 , Ta 2 O 5 , Nb 2 O 5 , Si 3 N 4 , and TiO 2 , an organic material including one of PGMEA and acryl, or a transparent film including one of PET, PC, PES, PI, PMMA, and COP. 
     In the embodiment shown in  FIGS. 2 through 6 , in a region in which the wiring electrodes  240  connected to the plurality of electrodes  220  and  230  are provided, a predetermined printing region for visually shielding the wiring electrodes  240  generally formed of a non-transparent metal material may be provided on the cover window. Hereinafter, a cover window  100  according to the embodiment of the present invention will be described in detail. 
       FIGS. 7 and 8  are views showing a cover window according to the embodiment of the present invention. 
     The cover window  100  may be disposed at the outermost position of the touchscreen to serve to receive a touch input from a contact object such as a finger, or the like. Referring to  FIG. 7 , the cover window  100  according to the present embodiment may include a first glass panel  110 , a printed portion  130  buried in the first glass panel  110 , and a second glass panel  150  bonded to the first glass panel  110 . In addition, the cover window  100  according to the present embodiment may further include a reinforcing layer  170 . The first and second glass panels  110  and  150  may be tempered glass. 
     As described above, the predetermined printing region may be provided on the cover window for visually shielding the wiring electrodes formed of a non-transparent metal material unlike the plurality of electrodes generally formed of a transparent material or an invisible material. 
     The printing region may be generally formed to have a thickness of 5 to 10 μm. In the case in which the printing region is formed on an upper surface of the cover window rather than being buried in the cover window, a step portion may be generated between the printing region and the cover window. 
     Here, in the case in which a predetermined adhesive layer or insulating layer is formed on the cover window so as to cover the printing region, air bubbles may be generated in the adhesive layer due to the step portion. In addition, at the time of printing a plurality of insulating layers so as to cover a thickness of the printing region, printing quality is decreased and turbidity is increased, such that optical characteristics may be deteriorated. 
     According to the present embodiment, the predetermined printing region may be buried in the cover window to prevent the step portion from being generated between the cover window and the predetermined printing region. 
     More specifically, the first glass panel  110  may include a concave part  115  formed in one surface thereof, and a printed portion  130  may be buried in the concave part  115 . Here, in order to prevent the step portion due to the printed portion  130 , the concave part  115  may have the same thickness as that of the printed portion  130 . As shown in  FIGS. 7 and 8 , the concave part  115  may have a rectangular shape or a semicircular shape. However, the shape of the concave part  115  is not limited to the shapes shown in  FIGS. 7 and 8 . 
     A color of the printed portion  130  may be black, white, gold, red, green, yellow, gray, purple, brown, blue, or a combination thereof. Materials capable of forming the printed portion  130  so as to have the above-mentioned respective colors will be described below in detail. 
     First, when a carbon based material (a graphene oxide or a diamond line carbon (DLC)), a chrome based oxide (CrO or CrO 2 ), a copper based oxide (CuO), a manganese based oxide (MnO 2 ), a cobalt based oxide (CoO), a sulfide (CoS 2  or Co 3 S 4 ), a nickel based oxide (Ni 2 O 3 ), HgTe, YBa 2 Cu 3 O7, MoS 2 , RuO 2 , PdO, InP, SnO, TaN, TaS 2 , or the like, is used, the printed portion  130  may be formed so as to have the black color. 
     In addition, when a titanium based oxide (TiO 2 ), an aluminum based oxide (Al 2 O 3 ), a magnesium based oxide (MgO), a sodium based oxide (Na 2 O), a lithium based oxide (Li 2 O), a beryllium based oxide (BeO), a magnesium based sulfide (MgS), MgF 2 , MgCo 3 , ZnO, ZnS, KNO 3 , KCl, KOH, Ga 2 O 3 , RbCl, RbF, BaTiO 3 , BaSO 4 , BaCl 2 , BaO, Ba(NO 3 ) 2 , BaCO 3 , BaOH, BaB 2 O 4 , SrTiO 3 , SrCl 2 , SrO, Y 2 O 3 , YCl 3 , YF 3 , ZrO 2 , ZrCl 4 , ZrF 4 , Nb 2 O 5 , NbOCl 3 , Mo(CO) 6 , CdCl 2 , InCl 3 , SnO 2 , Sb 2 O 3 , CsI, CsCl, CsF, Ta 2 O 5 , TaCl 5 , TaF 5 , or the like, is used, the printed portion  130  may be formed so as to have the white color. 
     Further, when a titanium based nitride (TiN), or the like, is used, the printed portion  130  may be formed so as to be gold, and when a copper based oxide (Cu 2 O), an iron based oxide (Fe 2 O 3 ), ZnTe, a Tris(bipyridine)ruthenium chloride, PdCl 2 , or CdSe, or the like, is used, the printed portion  130  may be formed so as to be red. 
     In addition, in the case that a chrome based oxide (Cr 2 O 3 ), MnO, NiO, MoCl 5 , BiI 3 , or the like, is used, the printed portion  130  may be formed so as to have the green color, and when a sodium based oxide (Na 2 O 2 ), K 2 O, CaO, V 2 O 5 , ZnSe, GaN, GaP, Rb 2 O, NbCl 5 , CdS, CdI 2 , In 2 O 3 , Sb 2 O 5 , Cs 2 O, WO 3 , Bi 2 O 3 , or the like, is used, the printed portion  130  may be formed so as to be yellow. 
     Further, when MgB 2 , Si 3 N 4 , RbOH, BaO 2 , ZrC, NbO, MoSi 2 , WC, Bi 2 Te 3 , or the like, is used, the printed portion  130  may be formed so as to be gray, and when Ru(acac) 3 , or the like, is used, the printed portion  130  may be formed so as to be purple. 
     In addition, when Pd(O 2 CCH 3 ) 2 , CdO, InSb, or a tantalum carbide, or the like, is used, the printed portion  130  may be formed so as to be brown, and when WCl 6 , or the like, is used, the printed portion  130  may be formed to be blue. 
     In addition, when a combination of the above-mentioned materials is used, the printed portion  130  may be formed to have a color corresponding to a combination of at least two of black, white, gold, red, green, yellow, gray, purple, brown, and blue. 
     Even in the case in which the concave part  115  is formed in the first glass panel  110  and the printed portion  130  is buried in the concave part  115 , a fine step portion may be generated due to an error inevitably caused by a manufacturing process. However, according to the present embodiment, one surface of the first glass panel  110  in which the concave part  115  is formed may be bonded to the second glass panel  170  to remove an influence of the fine step portion. In the case, one surface of the first glass panel  110  may be thermal-fusion-bonded to the second glass panel  170 , wherein the thermal-fusion-bonding may be performed at a temperature of 550° C. In addition, the first and second glass panels  110  and  170  may be double-side-bonded to each other using an anti-scattering film. 
     Then, the first and second glass panels  110  and  150  bonded to each other may be subjected to a chemical reinforcing treatment, such that the reinforcing layer  170  may be formed on surfaces of the first and second glass panels  110  and  150  bonded to each other. More specifically, the reinforcing layer  170  may be formed by subjecting the first and second glass panels  110  and  150  to the chemical reinforcing treatment using KNO3 at a temperature of 550° C. The reinforcing layer  170  may be formed over the entire surface of the cover window  100  to secure strength. 
       FIGS. 9A through 9G  are views showing a manufacturing process of the cover window according to the embodiment of the present invention. Hereinafter, the manufacturing process of the cover window according to the present embodiment will be described with reference to  FIGS. 9A through 9G . 
     A photo-resist PR may be deposited on one surface of the first glass panel  110  (See  FIG. 9A ), and exposure may be performed to form a mask pattern MP (See  FIG. 9B ). Then, one surface of the first glass panel  110  on which the mask pattern MP is formed is etched using a hydrofluoric acid aqueous solution, such that the concave part  115  may be formed in one surface of the first glass panel  110  (See  FIG. 9C ). Here, although the case in which the concave part  115  has a rectangular shape has been shown in  FIG. 9C , the concave part  115  may also have a semicircular shape as described above. 
     Then, the mask pattern MP remaining on one surface of the first glass panel  110  may be stripped using a stripper or the like (please see  FIG. 9D ), and the printed portion  130  having the same thickness as that of the concave part  115  may be formed in the concave part  115  formed in the first glass panel  110  using a printing method such as a screen printing method, an inkjet printing method, or the like (please see  FIG. 9E ). In this case, a fine step portion may be generated between the first glass panel  110  and the printed portion  130  due to an error inevitably caused in a manufacturing process. In order to remove the fine step portion, one surfaces of the first glass panel  110  and the second glass panel may be bonded to each other (please see  FIG. 9F ). The first and second glass panels  110  and  150  bonded to each other are subjected to the chemical reinforcing processes, such that the reinforcing layer  170  may be formed on the surfaces of the first and second glass panels  110  and  150  (please see  FIG. 9G ). 
     As set forth above, according to the embodiments of the present invention, the printing region is buried in one surface of one glass substrate and one surface of one glass substrate and another glass substrate are bonded to each other, whereby a step portion due to an error caused by a manufacturing process may be removed. 
     While the present invention has been shown and described in connection with the embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.