Abstract:
A method for shaping an object. The method includes the steps of preparing an attachment material having a glass transition temperature lower than that of the object, fixing the attachment material on the object, forming the object into a predetermined shape, heating the attachment material until the temperature is higher than its glass transition temperature, and cooling the attachment material and the object until the temperature is lower than the glass transition temperature of the attachment material. Additionally, shaping of the object and heating of the attachment material can achieve the same results.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method for shaping an object, and in particular to a method for shaping a flexible printed cable, so that the flexible printed cable can easily fit in a pivot-rotating mechanism. 
     2. Description of the Related Art 
     Generally, the conventional electronic device having a pivot-rotating mechanism, such as a cellular phone having a cover or a digital camera having a rotary lens and movable flash lamp, includes a main body and a rotary body. The signal is transmitted via a flexible printed cable (FPC) passing through the pivot-rotating mechanism between the main body and the rotary body. Nevertheless, because of the frequent movement between the main body and the rotary body, the flexible printed cable is frequently stretched such that the lifespan thereof is reduced. 
     Thus, there are two conventional methods to overcome the aforementioned problems. In the first method, the length of the flexible printed cable in the pivot-rotating mechanism is longer such that the flexible printed cable is subjected to reduce tensile stress. In the second method, the flexible printed cable in the pivot-rotating mechanism is wound directly or around a shaft. 
     Nevertheless, the current volume of electronic device is increasingly reduced. The size of the pivot-rotating mechanism is reduced as well. Additionally, the current electronic devices provide more and more functions so that the width of the flexible printed cable increases commensurately. Thus, in order not to increase the width of the flexible printed cable, multiple layers of the flexible printed cable are required and fit into the volume-reduced pivot-rotating mechanism. In the first conventional method, the manufacturing cost of the flexible printed cable is increased and the anti-torsion capability of the flexible printed cable is reduced. 
     In the second conventional method, the width of the flexible printed cable can exceed the width of the multiple layers of the flexible printed cable. Nevertheless, because the flexible printed cable has elasticity, it is inconvenient to wind the flexible printed cable directly or around a shaft. 
     Consequently, the invention provides a method to improve the aforementioned second conventional method. It is easier to fit the flexible printed cable in the rotating mechanism by the method of the invention. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a method for shaping an object. The method comprises the steps of: (a) preparing an attachment material having a glass transition temperature lower than that of the object; (b) fixing the attachment material on the object; (c) forming the object into a predetermined shape; (d) heating the attachment material until the temperature is higher than its glass transition temperature; and (e) cooling the attachment material and the object until the temperature is lower than the glass transition temperature of the attachment material. 
     Additionally, the steps (c) and (d) can be exchanged to have the same function. 
     A detailed description will be given by the following embodiments with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIG. 1  is a perspective exploded view showing the cellular phone of the invention; 
         FIG. 2  is a partially enlarged view according to  FIG. 1 ; 
         FIG. 3  shows the bent portion of the present flexible printed cable fit into a hollow shaft; 
         FIG. 4A , FIG.  4 B and  FIG. 4C  show the shaping steps for the present flexible printed cable; 
         FIG. 5  is a flowchart showing the first method of the invention for shaping an object; and 
         FIG. 6  is a flowchart showing the second method of the invention for shaping an object. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG.  1  and  FIG. 2 , the cellular phone includes a main body  102  and a rotary body (top cover)  101 . The main body  102  has a hollow shaft  1021  having a hole  1022 . A gap  1023  is formed on the hollow shaft  1021 . A flexible printed cable (hereinafter FPC)  202  has conducting circuits (not shown), connecting ends  2021 ,  2022  and a bent portion  2023 . The connecting ends  2021 ,  2022  are connected to the rotary body  101  and the main body  102 , respectively. The bent portion  2023  can reduce the tensile stress on the FPC  202  when the rotary body  101  rotates, thus increasing the lifespan of the FPC  202 . 
     Specifically, the originally flat FPC  202  is bent to a shape as shown in FIG.  2 . Then, the connecting end  2022  of the FPC  202  penetrates the hole  1022  and the gap  1023  of the hollow shaft  1021  of the main body  102 . The bent portion  2023  fits in the hole  1022 , as shown in FIG.  3 . 
     As mentioned above, the originally flat FPC  202  is bent to a shape as shown in FIG.  2 . Because the FPC  202  has elasticity, the bent portion  2023  is not easily maintained to fit in the hole  1022 . The bent portion  2023  has to be held carefully by hands or clips to fit in the hole  1022 . Thus, the reliability is low. In order to overcome the aforementioned problems, the invention provides the following methods to maintain the shape of the bent portion  2023 . 
     The First Method 
     Referring to  FIG. 4A , an attachment material  201  is provided. The attachment material  201  and the FPC  202  have a glass transition temperature T ga  and a glass transition temperature T gF , respectively. The glass transition temperature T ga  is lower than the glass transition temperature T gF . When the temperature exceeds the glass transition temperature T ga , the attachment material  201  becomes malleable. Then, when the temperature lowers, the attachment material  201  hardens in the new shape. 
     Referring to  FIG. 4B , the attachment material  201  is fixed on the FPC  202  by glue, heating press and/or other means. 
     Referring to  FIG. 4C , the FPC  202  having the attachment material  201  is bent into the bent portion  2023  by an external force. Then, the FPC  202 , in combination with the attachment material  201 , is heated to a temperature higher than the glass transition temperature T ga  to soften the attachment material  201  (the temperature does not exceed the temperature to damage the FPC  202 ). The FPC  202 , in combination with the attachment material  201 , is then cooled to the ambient temperature to harden the attachment material  201 . At this time, the attachment material  201  is shaped by the heating and external force. Even though the natural shape of the FPC  202  is not changed, the FPC  202  conforms to the same shape as the bent attachment material  201 . 
       FIG. 5  is a flowchart showing the first method. 
     The Second Method 
     Referring to  FIG. 4A , an attachment material  201  is provided. The attachment material  201  and the FPC  202  have a glass transition temperature T ga  and a glass transition temperature T gF , respectively. The glass transition temperature T ga  is lower than the glass transition temperature T gF . When the temperature reaches the glass transition temperature T ga , the attachment material  201  becomes malleable. Then, when the temperature lowers, the attachment material  201  hardens in the new shape. 
     Referring to  FIG. 4B , the attachment material  201  is fixed on the FPC  202  by glue, heating press and/or other means. Then, the FPC  202 , in combination with the attachment material  201 , is heated to a temperature higher than the glass transition temperature T ga  to soften the attachment material  201  (the temperature does not exceed the temperature to damage the FPC  202 ). 
     Referring to  FIG. 4C , the FPC  202  having the attachment material  201  is bent into the bent portion  2023  by an external force. Then, the FPC  202 , in combination with the attachment material  201 , is cooled to the ambient temperature to harden the attachment material  201 . At this time, the attachment material  201  is shaped by the heating and external force. Even though the original shape of the FPC  202  is not changed, the FPC  202  conforms to the same shape as the bent attachment material  201 . 
       FIG. 6  is a flowchart showing the second method. 
     In the first method, after the attachment material  201  is fixed on the FPC  202 , the FPC  202 , in combination with the attachment material  201 , is shaped to a bent soft circuit board via bending, heating and cooling. In the second method, after the attachment material  201  is fixed on the FPC  202 , the FPC  202 , in combination with the attachment material  201 , is shaped to a bent soft circuit board via heating, bending and cooling. The steps of bending and heating can be exchanged to achieve the object of the invention. 
     For example, if the bottom material of the FPC  202  is Polyimide (PI), with a glass transition temperature of about the range of 250° C., the attachment material  201  is made of Polycarbonate (PC), with a glass transition temperature of about the range of 120° C., and the Polycarbonate is fixed on the Polyimide by glue or heating press, a soft circuit board having a predetermined bent shape can be obtained by the aforementioned first or second method. 
     To summarize, the invention can generate a stable holding force for the FPC by the attachment material rather than by manual manipulation. Thus, the bent portion of the FPC can maintain the bent shape to fit in the pivot-rotating mechanism. The invention has significant benefits especially for the small pivot-rotating mechanism. In addition, the invention is not limited to a cellular phone. Specifically, the invention can be applied in any electronic device required to transmit signals via a pivot-rotating mechanism. 
     While the invention has been described by way of example and in terms of the preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments. 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.