Abstract:
A method for printing a label on a keypad, including the steps of providing a substrate plate, spraying ink on the substrate plate to form a label layer, solidifying the label layer, spraying ink around the label layer to form a primer layer, and solidifying the primer layer.

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a key labeling method, and more particularly, to a method used for printing a label on a keypad. 
     2. Description of Related Art 
     A commonly used key labeling method for printing a label on a keypad includes the following two steps. Providing a keypad substrate plate and forming a plurality of primer layers on the keypad substrate plate with screen printing technology; etching the primer layers to form a label with laser etching technology on the keypad substrate plate to finish the process of printing a label on the keypad. 
     However, the commonly used key labeling method has a relatively high manufacturing cost and is time-consuming because of the laser etching step. A second commonly used key labeling method is provided to decrease the manufacturing cost. The second commonly used key labeling method includes one step, printing a label layer and a plurality of the primer layers on the keypad substrate plate simultaneously. The laser etching step is thereby omitted, efficiently decreasing the manufacturing cost. However, when using the second commonly used key labeling method, the labeled layer and the primer layers easily mix with each other thereby obtaining a deformed and distorted label on the keypad substrate plate. 
     Therefore, there is room for improvement in the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       Many aspects of the embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. Wherever possible, the same reference numerals are used throughout the drawings to refer to the same or like elements of an embodiment. 
         FIG. 1  is a flow chart of an embodiment of a key labeling method. 
         FIG. 2  is a schematic view of a substrate plate prepared for printing a label. 
         FIG. 3  is a schematic view of the substrate plate having a label layer formed thereon. 
         FIG. 4  is a schematic view of the substrate plate having a primer layer formed thereon. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 through 4 , an embodiment of a key labeling method includes the following steps. 
     In step S 101 , a substrate plate  10  is provided. The substrate plate  10  is made of transparent materials. In one embodiment, the substrate plate  10  is a keypad of a mobile phone having a pressing surface  11  and a printing surface  13  (shown in  FIG. 3 ) opposite to the pressing surface  11 . 
     In step S 102 , the printing surface  13  of the substrate plate  10  is cleaned to contaminants, that have been deposited on the printing surface  13 . In one embodiment, the printing surface  13  of the substrate plate  10  is cleaned by using alcohol to wash or wipe the printing surface  13 . 
     In step S 103 , a label layer  131  is formed on the printing surface  13  of the substrate plate  10 . In one embodiment, a liquid UV ink (ultraviolet printing ink) is sprayed on the printing surface  13  of the substrate plate  10  by a solvent ink-jet printer (not shown) to form the label layer  131 . In one embodiment, the UV ink is transparent ink. The solvent ink-jet printer includes an ink-jet head. The distance between an ink jet head of the solvent ink-jet printer and the label layer  131  varies from about 1.5 mm to about 2.5 mm, while the solvent ink-jet printer is working. 
     In step S 104 , the label layer  131  is solidified. In one embodiment, ultraviolet rays illuminate the label layer  131  to quickly solidify the label layer  131  of the printing surface  13 . The radiant energy of the ultraviolet rays varies from 900 Joule (J) to 1100 J. A preferred radiant energy of the ultraviolet rays is 1000 J. An illumination time of the label layer  131  is preferred to be about 20 seconds (s) to about 40 s. 
     In step S 105 , a primer layer  133  is formed on the printing surface  13  of the substrate plate  10  around the label layer  131 . In one embodiment, a liquid UV ink is sprayed on the printing surface  13  to form the primer layer  133 . After solidification, the label layer  133  is in a solid state. The primer layer  133  is in a liquid state and forms a surface tension. The primer layer  133  tends to withdraw under the affect of the surface tension, this result in the segregating of the primer layer  133  from the label layer  131 . Thus, the mingling between the primer layer  133  and the label layer  131  is difficult to occur thereby the label being clear to see. In one embodiment, the UV ink is transparent ink to enable the color of the primer layer  133  to be displayed by a backlight in the dark. 
     In step S 106 , the primer layer  133  is solidified. In one embodiment, ultraviolet rays illuminate the primer layer  133  to quickly solidify the primer layer  133  of the printing surface  13 . The radiant energy of the ultraviolet rays varies from 900 Joule (J) to 1100 J. A preferred radiant energy of the ultraviolet rays is 1000 J. An illumination time of the label layer  131  is preferred to be about 20 seconds (s) to about 40 s. 
     The liquid UV ink of the label layer  131  and the primer layer  133  may also be sprayed by a solvent ink-jet printer, the liquid UV ink of the label layer  131  and the primer layer  133  each may be achieved at one time. 
     An electrostatic dust collecting process may be applied to the printing surface  13  of the substrate plate  10  after using alcohol to wash or wipe the printing surface in step S 102  for further cleaning of the printing surface  13 . In one embodiment, an electrostatic dust collector (not shown) is provided to clean the remaining contaminants from the printing surface  13  of the substrate plate  10 . 
     The steps of S 102  may also be omitted if the substrate plate  10  provided is clean enough. 
     It is to be understood that the label layer  131  and the primer layer  133  may also be solidified by the suns rays. 
     It is to be understood that the label layer  131  and the primer layer  133  may also be sprayed on the pressing surface  11 , thus, a protection layer is needed here to cover the pressing surface  11  when in use. 
     It is to be understood that the key labeling method may further include a polishing or burnishing process applied to the pressing surface  11  and the printing surface  13  of the substrate plate  10  after step S 101 , in order to decrease a roughness concentration of the substrate plate  10 . 
     It is to be understood that the present disclosure is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.