Patent Publication Number: US-2010112309-A1

Title: Appearance Part of Electronic Device and Method for Manufacturing the Same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 0970142004 filed in Taiwan, Republic of China on Oct. 31, 2008, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to an appearance part of an electronic device and, more particularly, to an appearance part of an electronic device made of polystyrene and a method for manufacturing the same. 
     2. Description of the Related Art 
     With development of human material civilization, a method for manufacturing a product via a mold has become necessary technology in modern life. The method for manufacturing a product via a mold is divided into injection molding process, blow molding process, press forming process, foam molding process and so on. During the injection molding process, a material such as plastic is heated, and the molten material is then injected into a mold. The mold is separated and a product is taken away after the material injected into the mold is cooled. 
     The injection molding process spends short manufacturing time and less money; and further, the injection molding process can manufacture products with complex shapes. so that it has a gradually widened application range. In general, a conventional appearance part of an electronic device is mostly made of plastic, and the injection molding technology is often used to manufacture the same. 
     With the development of consuming electronic devices, functions and applications have more and more variety, and therefore how to attract consumers to buy the consuming electronic devices is a considerable problem. According to the aforementioned, an appearance design of the consuming electronic devices becomes an important factor. However, if an appearance part of an electronic device formed by injection molding process does not have additional painting or coloring, basically the electronic device only presents a uniform color of the plastic itself, which appears dull and fails to satisfy the present needs about the appearance part of the electronic device. 
     In a subsequent development, a plastic injection product of a certain color is obtained by mixing plastic and color materials before the injection molding process. Otherwise, a molding machine with two injection devices is used to inject plastic of two colors or different types of plastic. However, the above methods resulted in increasing manufacturing time; and further, the product has a clear color without mixture, which fails to provide varied appearances. 
     BRIEF SUMMARY OF THE INVENTION 
     This invention provides an appearance part of an electronic device manufactured by processing first plastic and second plastic via a color-mixing molding process. The first plastic and the second plastic have a melt flow index. The first plastic and the second plastic are polystyrene of different colors or different transparency. In one embodiment of the invention, the appearance part of the electronic device may be a casing of an electronic device or a skin for decorating an appearance of an electronic device. 
     In addition, the invention further provides a method for manufacturing an appearance part of an electronic device, and the method is performed in a color-mixing molding device. The method includes the following steps. First, a first plastic and a second plastic are provided. The first plastic and the second plastic are polystyrene of different colors. The first plastic and the second plastic are then injected into the color-mixing molding device. A color-mixing molding process is performed for the first plastic and the second plastic in the color-mixing molding device. The first plastic and the second plastic are ejected into a mold via a gate of the mold to form the appearance part of the electronic device. 
     In this invention, polystyrene of two different colors is used as materials of the color-mixing molding process. By controlling the manufacturing conditions of the color-mixing molding process, such as a melt flow index of the two kinds of the plastic and pressure exerted on the two kinds of the plastic and so on, in cooperation with the location of the gate of the mold, the appearance part of the electronic device having different decorative patterns can be manufactured, thus to solve the problem of the uniform color and the long manufacturing time in the prior art. 
     These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a first schematic diagram showing an appearance part of an electronic device according to one preferred embodiment of the invention; 
         FIG. 1B  is a second schematic diagram showing an appearance part of an electronic device according to one preferred embodiment of the invention; 
         FIG. 1C  is a third schematic diagram showing an appearance part of an electronic device according to one preferred embodiment of the invention; 
         FIG. 1D  is a fourth schematic diagram showing an appearance part of an electronic device according to one preferred embodiment of the invention; 
         FIG. 2A  is a flow chart showing a method for manufacturing an appearance part of an electronic device according to one preferred embodiment of the invention; 
         FIG. 2B  is a flow chart showing a color-mixing molding process according to one preferred embodiment of the invention; 
         FIG. 3A  is a schematic diagram showing a color-mixing molding device according to one preferred embodiment of the invention; and 
         FIG. 3B  is a sectional schematic diagram showing a pipe of a color-mixing molding device. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIGS. 1A to 1D  are first to fourth schematic diagrams showing an appearance part of an electronic device according to one preferred embodiment of the invention, respectively. Please refer to  FIGS. 1A to 1D , qn appearance part of an electronic device is manufactured by processing a first plastic and a second plastic via a color-mixing molding process. The first plastic and the second plastic are polystyrene of different colors or different transparency. In one preferred embodiment, the polystyrene may be GPPS or HIPS. 
     In this embodiment of the invention, the appearance part of the electronic device may be a casing of an electronic device, a skin for decorating an appearance of an electronic device, or a decoration at a side edge of an electronic device and so on. However, the invention is not limited thereto. The appearance parts  11 ,  12  of the electronic device are casings as  FIG. 1A  and  FIG. 1B . The appearance parts  13 ,  14  of the electronic device are skins as  FIG. 1C  and  FIG. 1D . In one embodiment of the invention, the appearance part of the electronic device has a grain pattern. 
     In one embodiment of the invention, a temperature of the first plastic and the second plastic for manufacturing the appearance part of the electronic device in a color-mixing molding process is between 170° C. and 185° C.; And further, a melt flow index of the first plastic and the second plastic is about between 0.8 g/min and 1.5 g/min under the above temperature. 
     Please refer to  FIGS. 2A to 3B . According to the embodiment of the invention, the appearance part of the electronic device is manufactured by processing the first plastic and the second plastic via a color-mixing molding device. The manufacturing flow paths are further described hereinbelow.  FIG. 2A  is a flow chart showing a method for manufacturing an appearance part of an electronic device according to one preferred embodiment of the invention.  FIG. 2B  is a flow chart showing a color-mixing molding process according to one preferred embodiment of the invention.  FIG. 3A  is a schematic diagram showing a color-mixing molding device according to one preferred embodiment of the invention.  FIG. 3B  is a sectional schematic diagram showing a pipe of the color-mixing molding device. 
     Please refer to  FIG. 2A , the method for manufacturing an appearance part of an electronic device includes the following steps. 
     Step S 1 : providing plastic. 
     A plastic  21  and a second plastic  22  are provided. The first plastic  21  and the second plastic  22  are polystyrene of different colors or different transparency. 
     Step S 2 : injecting the plastic. 
     The first plastic  21  and the second plastic  22  are then injected into a color-mixing molding device  2 , respectively. 
     Step S 3 : performing a color-mixing molding process. 
     In addition, please refer to  FIG. 2B  and  FIG. 3A , the color-mixing molding device  2  includes two heating stirrers  231 ,  232 , two pipes  241 ,  242 , a nozzle  26 , and a barrel  25  connecting the pipes  241 ,  242  and the nozzle  26 . The color-mixing molding process as shown in  FIG. 2B  includes the following steps. 
     Step P 1 : heating and stirring the plastic. 
     The heating stirrers  231 ,  232  are used to heat and stir the first plastic  21  and the second plastic  22 , respectively, to allow the temperature thereof to be between 170° C. and 185° C. 
     Step P 2 : injecting the plastic. 
     A melt flow index of the first plastic  21  and the second plastic  22  is about between 0.8 g/min and 1.5 g/min after step P 1 . The first plastic  21  and the second plastic  22  are then injected into the pipe  241  and the pipe  242 , respectively. 
     Step P 3 : pushing the plastic. 
     Please refer to  FIG. 3B , screws  27  are disposed in the pipe  241  and the pipe  242 , respectively. Pressure is exerted on the first plastic  21  and the second plastic  22  via rotation of the screws  27 , respectively, to push them to flow toward the barrel  25 . In one preferred embodiment, the pressure exerted on the first plastic  21  is between 45 kg/cm 2  and 65 kg/cm 2 , and the pressure exerted on the second plastic  22  is between 45 kg/cm 2  and 65 kg/cm 2 . In addition, a flow speed of the first plastic  21  in the pipe  241  is between 50 cm 2 /sec and 70 cm 2 /sec, and a flow speed of the second plastic  22  in the pipe  242  is between 45 cm 2 /sec and 65 cm 2 /sec. 
     In the pushing step, the pressure and the flow speed may vary with a mold cavity design of the mold. The method for manufacturing an appearance part of an electronic device in this invention is not limited thereto. 
     Step P 4 : converging the plastic. 
     The first plastic  21  and the second plastic  22  are converged in the barrel  25 . The first plastic  21  and the second plastic  22  in the barrel  25  do not merge with each other since the melt flow index of the polystyrene is between 0.8 g/min and 1.5 g/min; and further, they only generate little interactive diffusion at the contacting surface so that the first plastic and the second plastic located in the barrel  25  have clear gradation and a gradually layered effect at their boundary. 
     Step P 5 : ejecting the plastic. 
     The first plastic  21  and the second plastic  22  are ejected via the nozzle  26  and ejected into a mold  29  via a gate  291  of the mold  29  to form an appearance part of an electronic device. 
     In the ejecting step, if the gate  291  is disposed at a center of a surface  292  of the mold  29 , the formed appearance part of the electronic device may have a grain pattern with two alternative colors, and the boundary of the two colors also has a gradually layered effect. However, the grain pattern is just one example. That is, by changing the location of the gate  291  at the surface  292  or intermittently ejecting at least one of the first plastic  21  and the second plastic  22  into the mold  29 , the appearance part of the electronic device can have different decorative patterns. 
     Although the present invention has been described in considerable detail with reference to certain preferred embodiments thereof, the disclosure is not for limiting the scope of the invention. Persons having ordinary skill in the art may make various modifications and changes without departing from the scope and spirit of the invention. Therefore, the scope of the appended claims should not be limited to the description of the preferred embodiments described above.