Patent Publication Number: US-2013248337-A1

Title: Keycap and method of manufacturing the same

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a keycap and a method of manufacturing keycap, and especially relates to a keycap with pattern thereon and a method therefor. 
     2. Description of the Prior Art 
     Current keycaps are usually made by injection-molding. If it is required to form a pattern on the keycap, the pattern is usually formed in another process separate from the above injection-molding process. For an example of a keycap used in a backlight keyboard, a transparent cap is first formed by injection-molding. The cap is then printed or coated with multiple layers of ink thereon by an order. A pattern is formed by using laser light to cut (or mark) the multiple layers of ink. At last, a protection gel layer is formed on the multiple layers, especially over the pattern by spraying and is treated by a curing process. Afterward, the keycap with the pattern is therefore obtained. Therefore, the keycap needs many processes, leading to a great consumption of time, especially of much time to form the multiple layers of ink. Besides, the variations of the processes are large relatively. 
     SUMMARY OF THE INVENTION 
     An objective of the invention is to provide a method of manufacturing keycap, which uses an in-mold transfer method and a high energy optical engraving method to manufacture a keycap with a pattern thereon so as to reduce the total manufacturing time and further to improve the manufacturing stability. 
     The method of manufacturing keycap of the invention includes the following steps: injection-molding a cap with a layer structure of ink thereon by an in-mold transfer method; then forming a pattern on the layer structure of ink by a high energy optical engraving method; and afterward forming a light-permeable protection layer on the layer structure of ink to cover the pattern. Therefore, the invention uses the in-mold transfer method for enhancing the efficiency of forming the layer structure of ink on the cap and also for improving the binding strength between the layer structure of ink and the cap, which solves the problems in the prior art that the conventional manufacturing of a keycap with a pattern formed thereon consumes much time and the variations of the processes are large relatively. 
     Another objective of the invention is to provide a keycap, which is made by the method of the invention. The keycap of the invention includes a cap, a layer structure of ink, and a light-permeable protection layer. The layer structure of ink is formed on the cap by an in-mold transfer method and has a pattern which is formed by a high energy optical engraving method. The light-permeable protection layer is formed on the layer structure of ink to cover the pattern. Similarly, the invention uses the in-mold transfer method to improve the binding strength between the layer structure of ink and the cap, which enhances the product reliability. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top view of a keycap of a preferred embodiment according to the invention. 
         FIG. 2  is a sectional view of the keycap along the line X-X in  FIG. 1 . 
         FIG. 3  is a primary flow chart of a method of manufacturing keycap according to the invention. 
         FIG. 4  is a detailed flow chart for manufacturing the keycap in  FIG. 1 . 
         FIG. 5  is a sectional view of a transfer film used in the manufacturing flow by  FIG. 4 . 
         FIGS. 6 through 11  are schematic diagrams illustrating the manufacturing according to the flow chart shown by  FIG. 4 . 
         FIG. 12  is a sectional view of a keycap of another preferred embodiment according to the invention. 
         FIG. 13  is a sectional view of a transfer film used for the keycap in  FIG. 12 . 
     
    
    
     DETAILED DESCRIPTION 
     Please refer to  FIGS. 1 through 3 .  FIG. 1  is a top view of a keycap  1  of a preferred embodiment according to the invention.  FIG. 2  is a sectional view of the keycap  1  along the line X-X in  FIG. 1 .  FIG. 3  is a primary flow chart of a method of manufacturing keycap according to the invention. As shown by the step S 100 , the method is first to injection-mold a cap  12  with a layer structure of ink  14  thereon by an in-mold transfer method. As shown by the step S 200 , the method is then to form a pattern  16  on the layer structure of ink  14  by a high energy optical engraving method. In the embodiment, the pattern  16  presents a letter A, but the invention is not limited thereto. Afterward, as shown by the step S 300 , the method is to form a light-permeable protection layer  18  on the layer structure of ink  14  to cover the pattern  16 . Thereby, the manufacturing of the keycap  1  uses the in-mold transfer method for enhancing the efficiency of forming the layer structure of ink  14  on the cap  12  and also for improving the binding strength between the layer structure of ink  14  and the cap  12 , which solves the problems in the prior art that the conventional manufacturing of a keycap with a pattern formed thereon consumes much time and the variations of the processes are large relatively. 
     In the embodiment, the in-mold transfer method uses a method of in-mold decoration by roller in the art of in-mold decoration. The high energy optical engraving method uses laser light. These will be described further later, but the invention is not limited thereto. Please also refer to  FIGS. 4 through 11 .  FIG. 4  is a detailed flow chart for manufacturing the keycap  1 .  FIG. 5  is a sectional view of a transfer film  15   a  used in the manufacturing flow by  FIG. 4 .  FIGS. 6 through 11  are schematic diagrams illustrating the manufacturing according to the flow chart shown by  FIG. 4 ; therein, the transfer film  15   a  is shown by bold lines in  FIGS. 6 through 8 . 
     In the embodiment, the step S 100  in  FIG. 3  is implemented by the steps S 110 , S 120 , S 130  and S 140  in  FIG. 4 . As shown by the step S 110 , the method of manufacturing keycap includes providing a transfer film  15   a  and an injection mold  2 . As shown in  FIG. 5 , the transfer film  15   a  is a layer structure and includes a carrier  152 , a release layer  154  formed on the carrier  152 , a masking ink layer  142  formed on the release layer  154 , a light-permeable ink layer  144  formed on the masking ink layer  142 , and an adhesive layer  156  formed on the light-permeable ink layer  144 . Therein, the masking ink layer  142  and the light-permeable ink layer  144  form the layer structure of ink  14 . As shown in  FIG. 6  and  FIG. 7 , the injection mold  2  includes an upper mold  22  and a lower mold  24 . The upper mold  22  and the lower mold  24  join with each other to form a cavity  26  therebetween. 
     As shown by the step S 120 , the method is then to place the transfer film  15   a  in the cavity  26  such that the carrier  152  sticks on an inner wall of the cavity  26 . In a practical operation, the transfer film  15   a  is placed on the lower mold  24  corresponding to the cavity  26  by rollers  3  and sticks on the inner wall closely further by vacuum absorption, as shown in  FIG. 6 . Afterward, the method is to join the upper mold  22  with the lower mold  24  to form the cavity  26 , as shown in  FIG. 7 . 
     As shown by the step S 130 , the method is then to inject a plastic material  4  into the cavity  26 , as shown in  FIG. 8 . When the plastic material  4  in the cavity  26  becomes cool to form the cap  12 , the layer structure of ink  14  sticks on the cap  12  by the adhesive layer  156 . Because the plastic material  4  is compressed to be injected into the cavity  26 , the binding strength between the cap  12  and the layer structure of ink  14  is usually stronger than that by a method of spraying or spreading adhesive under normal temperature and pressure, which avoids peeling of the layer structure of ink  14 . In addition, in the embodiment, the keycap  1  is used for a backlight keyboard. The plastic material  4  is made of light-permeable plastic material so that the cap  12  is light-permeable. However, the invention is not limited thereto. 
     After the injection mold  2  is opened, the cap  12  with a part of the transfer film  15   a  thereon can be taken out from the cavity  26 . As shown by the step S 140 , By use of the release layer  154 , the carrier  152  can be peeled off from the layer structure of ink  14 . After the peeling, a sectional view of the cap  12  with the layer structure of ink  14  attached thereon is shown by  FIG. 9 . 
     In the embodiment, the step S 200  in  FIG. 3  is implemented by the steps  5210  and  5220  in  FIG. 4 . As shown by the step S 210 , the method of manufacturing keycap is then to irradiate the masking ink layer  142  of the layer structure of ink  14  with a laser light beam. As shown by the step S 220 , the method is to cut (or mark) the masking ink layer  142  to form the pattern  16 ; the light-permeable ink layer  144  is still reserved. The cap  12  with the layer structure of ink  14  after the cutting (or marking) is shown in  FIG. 10 ; therein, the pattern  16  is located on the top surface  122  of the cap  12 . 
     In the embodiment, the step S 300  in  FIG. 3  is implemented by the steps  5310  and  5320  in  FIG. 4 . As shown by the step S 310 , the method of manufacturing keycap is then to form a first ultraviolet-curing gel layer  19   a  on the layer structure of ink  14 , as shown in  FIG. 11 ; therein, the first ultraviolet-curing gel layer  19   a  is formed on the top surface  122  and the side surfaces  124  of the cap  12  to cover the pattern  16 . In practice, the hollow portion of the pattern  16  can be filled with the first ultraviolet-curing gel layer  19   a . As shown by the step S 320 , the method is then to irradiate the ultraviolet-curing gel layer  19   a  with ultraviolet to cure the ultraviolet-curing gel layer  19   a  to form the light-permeable protection layer  18 , as shown in  FIG. 2 . Afterward, the keycap  1  is therefore obtained. 
     Please refer to  FIG. 12  and  FIG. 13 .  FIG. 12  is a sectional view of a keycap  5  of another preferred embodiment according to the invention.  FIG. 13  is a sectional view of a transfer film  15   b  used for the keycap  5  in  FIG. 12 . In the embodiment, compared to the transfer film  15   a , the transfer film  15   b  further includes a second ultraviolet-curing gel layer  19   b  located between the release layer  154  and the masking ink layer  142 ; that is, the release layer  154 , the second ultraviolet-curing gel layer  19   b , the layer structure of ink  14  and the adhesive layer  156  are formed on the carrier  152  in order. Therefore, in the above step S 140 , the carrier  152  is peeled off from the second ultraviolet-curing gel layer  19   b  by the release layer  154 . In the above steps S 210  and S 220 , the laser light beam cuts (or marks) the second ultraviolet-curing gel layer  19   b  and the layer structure of ink  14  simultaneously to form the pattern  16 ; that is, the pattern  16  is formed by the second ultraviolet-curing gel layer  19   b  and the layer structure of ink  14  simultaneously and is located above the top surface  122  of the cap  12 . The second ultraviolet-curing gel layer  19   b  has covered the top surface  122  and the side surfaces  124  of the cap  12 , so in the above step S 310 , the first ultraviolet-curing gel layer  19   a  just needs to be formed on the second ultraviolet-curing gel layer  19   b  and above the top surface  122  of the cap  12  to cover the pattern  16 . Therefore, the layer structure of ink  14  is covered by the first ultraviolet-curing gel layer  19   a  together with the second ultraviolet-curing gel layer  19   b . Besides, in the above step S 320 , the ultraviolet irradiates the first ultraviolet-curing gel layer  19   a  and the second ultraviolet-curing gel layer  19   b  simultaneously to be cured to form the light-permeable protection layer  18 ; that is, the light-permeable protection layer is formed by the ultraviolet-cured layers by curing the ultraviolet-curing gel layers  19   a  and  19   b . Similarly, such light-permeable protection layer  18  also can provide entire protection to the layer structure of ink  14  and the pattern  16 . 
     It is added that in practice, the transfer films  15   a  and  15   b  are not limited to the layer structures disclosed in the above embodiments. It goes without saying that they can include more layers in accordance with an actual product specification. In addition, in the above embodiments, the keycaps  1  and  5  use the ultraviolet-cured layers formed by curing the ultraviolet-curing gel layers  19   a  and  19   b , but the invention is not limited thereto. In practice, any structure capable of forming a light-permeable protection layer can be taken as the light-permeable protection layer  18  of the invention, such as hardened resin. 
     As discussed above, compared with the prior art, the invention uses the in-mold transfer method to greatly save the manufacturing time of attaching the layer structure of ink on to the cap and also to enhance the binding strength between the layer structure of ink and the cap so as to effectively reduce the peeling probability of the layer structure of ink. Furthermore, the invention uses the transfer film to form the layer structure of ink with uniform thickness, which can solve a problem of non-uniform coated thickness due to a spraying angle of a conventional spraying method. In addition, when the used transfer film includes a curing gel layer (such as the ultraviolet-curing gel layer), after the pattern is formed, only the portion of the cap corresponding to the pattern (i.e. the top surface of the cap) needs to be covered by another hardened layer. Thereby, the purpose of the complete protection effect on the layer structure of ink also can be achieved. Besides, the extent of non-uniform thickness which is maybe produced by the coating of the curing gel layer on the cap can be reduced. 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.