Abstract:
The self-luminescence keypad structure includes a backlight module and a self-luminescence keycap structure including a self-luminescence material. For example, a self-luminescence layer comprising the self-luminescence material is disposed, at least a member of the self-luminescence keycap structure is allowed to include the self-luminescence material, or a hard coat including the self-luminescence material is coated on the surface, thereby the keypad structure has the self-luminescence function upon receiving a light from the backlight module. Accordingly, in the dark, the figures on keycaps can be seen even though the backlight is turned off, and thus the electrical power saving can be achieved and the battery lifetime can be increased.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a keypad structure, and particularly to a self-luminescence keypad structure, which can self-luminesce by receiving light emitted from the backlight module of the keypad structure. 
         [0003]    2. Description of the Prior Art 
         [0004]    Electronic products such as cell phones (or mobile phones), personal digital assistants (PDAs) and the like usually have keypads disposed on them. In present market, keypads are mainly categorized into metal keypads and plastic keypads, and the latter are used more commonly. There are figures such as numerals, symbols and English letters on the keypads. Backlight modules such as light emitting diodes (LEDs) are usually disposed under the keypads to provide illumination for keypads, thus it is convenient for users to use in the dark. However, in order to save electrical power of battery, a function item for automatically turning off the illumination is provided, so users can set the illumination duration as desired. The longer the light is turned on, the more quickly the electrical power is consumed. But, consumers usually expect that electrical power of electronic products can last as long as possible. 
         [0005]    Taiwan patent number M271245 discloses a photosensitive keypad as shown in  FIG. 1 . It has a keypad body  10 , a photosensitive color layer  12  disposed at the bottom side of the keypad body  10 , and a plurality of figures such as letters, symbols and the like located on the photosensitive color layer  12 . The photosensitive color layer  12  has a first color change upon receiving a light energy and then a second color change upon receiving another light energy, or more, to achieve dual mode visual effect. It is characterized in providing keypad appearance with various color changes and multiple visual effect, to overcome conventional disadvantages of keypads about having just a fixed color or single color change. Therefore, it can be known that the photosensitive color layer  12  is used for causing color change of the appearance, but not for providing light to reach the backlight function. 
         [0006]    Nevertheless, due to continuous development of power saving of electronic products, there is still a need for a novel power saving keypad structure. 
       SUMMARY OF THE INVENTION 
       [0007]    An objective of the present invention is to provide a self-luminescence keypad structure having the self-luminescence function, and luminescence may be emitted after the keypad absorbs a light from the backlight module; therefore, the self-luminescence keypad structure can save electrical power. 
         [0008]    The self-luminescence keypad structure according to the present invention includes a printed circuit board, a metal dome disposed above the printed circuit board, a plunger located above the metal dome, a backlight module located above the printed circuit board to provide a first light, and a self-luminescence keycap structure located above the backlight module and corresponding to the plunger, wherein the self-luminescence keycap structure includes a self-luminescence material. As the backlight module provides the first light, the self-luminescence material absorbs the first light and emits a second light. As the backlight module stops providing the first light, the self-luminescence material continues emitting the second light. 
         [0009]    In addition to the backlight module, the self-luminescence keypad structure of the present invention has the members, components, elements or parts in the keycap of the keypad structure, any of which is allowed to have the self-luminescence material. Therefore, after the backlight module is turned off to stop providing light, the self-luminescence keypad structure still can emit luminescence for a while, for serving as a backlight of the keypad. For example, while the cell phone rings in the dark, the self-luminescence keypad structure can absorb the light emitted from the light source (such as LED) to achieve the self-luminescence effect, and then the figures of the keypad can be seen clearly. The electrical power can be accordingly saved, and the usable time of the battery after one charge can be increased, such that the lifetimes of both the battery and the light source can be prolonged. 
         [0010]    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 
         [0011]      FIG. 1  shows a schematic diagram illustrating a conventional keypad color; 
           [0012]      FIG. 2  shows a schematic diagram according to an embodiment of an application of the keypad structure of the present invention to a cell phone; and 
           [0013]      FIGS. 3 to 5  show schematic diagram illustrating some embodiments of the keycap structures of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    According to the self-luminescence keypad structure of the present invention, a self-luminescence keycap structure includes a self-luminescence material. For example, a self-luminescence material layer can be inserted into the self-luminescence keycap structure, at least a member of the self-luminescence keycap structure is allowed to include the self-luminescence material, or a hard coating including the self-luminescence material is coated on the surface, thereby the keypad structure performs the self-luminescence function upon receiving a light from the backlight module. The keycap structure is not especially limited, which may be a keycap structure composed of plastic and rubber, or formed by injection molding, UV (ultraviolet)-light curing, or lithography, for example. The self-luminescence material may comprise rare earth materials, but is not limited to these. Other materials, such as fluorescence materials, phosphorescence materials, and the like, able to emit light after receiving irradiation, which can be blended into materials of the members of the keypads, or can be alone or blended into other materials such as plastic or coating materials to form a lamella or a coating layer, may be usable in the present invention.  FIG. 2  shows the self-luminescence keypad structure  22  of the present invention being used in a cell phone  20 . 
         [0015]      FIG. 3  to  FIG. 5  respectively show three embodiments according to the present invention, but the present invention is not limited thereto. An embodiment according to the present invention is shown in  FIG. 3 . The self-luminescence keypad structure  40  of an embodiment according to the present invention includes a self-luminescence keycap structure including a keycap layer  42 , a plastic film  44  and a self-luminescence material layer  46 . The keycap layer  42 , which is in a keycap shape, may comprise a material which may be a transparent resin such as polycarbonate (PC), poly (ethylene terephthalate) (PET), or a transparent blend composed of acrylonitrile butadiene styrene (ABS) resin and a variety of resins, in some embodiments. The transparent blend may be, for example, a transparent ABS resin formed through blending ABS resin and polymethylmethacrylate (PMMA). Herein, the term “transparent” may mean transparent, translucent, light-penetratable, or light-transmissive. Thus, transparent or hollowed-out materials or members are all referred to as being transparent, and the color thereof is not particularly limited. The plastic film  44  conformally covers the top surface of the keycap layer  42 , wherein the plastic film  44  may be a film having plasticity, such as a PC film or the like. The self-luminescence material layer  46  is located between the keycap layer  42  and the plastic film  44 . The self-luminescence material layer  46  is formed through mixing a self-luminescence material and a plastic or coating material, for example, mixing a rare earth material and a PC material; or, optionally, the self-luminescence material layer  46  may further include an adhesive material for serving an adhesive layer as well. A print layer  48  may be optionally disposed between the plastic film  44  and the keycap layer  42 , to provide the keypad with figures such as background colors, letters, symbols or the like. In this embodiment, the print layer  48  is disposed between the self-luminescence material layer  46  and the keycap layer  42 , but not limited thereto. For example, the print layer  48  also can be disposed between the self-luminescence material layer  46  and the plastic film  44 . An elastomer layer  50  may be further disposed under the keycap structure, and it may be rubber to provide elasticity. In this embodiment, the elastomer layer  50  and a plunger  52  may be monolithically formed. 
         [0016]    The backlight module  54  is located under the elastomer layer  50  to provide light. The keycap layer  42 , the plastic film  44 , and the optional print layer  48  are transparent. As the backlight module  54  is turned on to provide light, the self-luminescence material layer  46  absorbs the light to emit luminescence. As the backlight module  54  is turned off to stop providing light, the self-luminescence material layer  46  can continue emitting luminescence for a while because of the self-luminescence function. Therefore, the luminescence emitted from the self-luminescence material layer  46  can serve as the backlight of the keypad structure, so that the figures of the keypad can be seen for an increased time period without consuming extra electrical power, and the effect of power saving is achieved. 
         [0017]    Since the whole self-luminescence keycap structure is substantially transparent, a light shielding layer  51  may be allowed to be further disposed on the top surface of the elastomer layer  50  to block the light emitted from the backlight module  54 , while exposing the keytop. Thus the light is just emitted through the keytop to outside. Under the elastomer layer  50  and the plunger  52 , a dome  56  is disposed correspondingly to the location of the plunger  52 . The materials of the dome  56  may be metal or conductive plastic, and a printed circuit board  58 , preferably a flexible printed circuit board, is disposed under the dome  56 . The dome  56  may be fixed on the printed circuit board  58  by using a dome sheet, for example. 
         [0018]    The self-luminescence material layer  46  in the aforementioned embodiment is located between the keycap layer  42  and the plastic film  44 . However, optionally, the self-luminescence material layer  46  may be located under the keycap layer  42 , or the self-luminescence material layer  46  may be coated on the top surface of the plastic film  44  by a coating method. 
         [0019]    Alternatively, at least a member of the self-luminescence keycap structure may be allowed to include the self-luminescence material, instead of disposing the self-luminescence material layer  46 . For instance, by blending the self-luminescence material in the materials of the keycap layer  42  or the plastic film.  44 , the resulted keycap layer  42  or the plastic film  44  will include the self-luminescence material. The blending amount of the self-luminescence material depends on the materials of members of the keycap structure and the desired intensity of luminescence. 
         [0020]    Another embodiment according to the present invention is shown in  FIG. 4 . The keycap structure of the self-luminescence keypad structure  60  includes a key-shaped layer  62  and an elastomer layer  64  located under the key-shaped layer  62 , both of them are transparent. For example, the material of the key-shaped layer  62  may be PC or ABS, and the material of the elastomer layer  64  may be TPU. Both may combine with each other by a co-molding process. The material of the key-shaped layer  62  or the material of the elastomer layer  64  can be blended with the self-luminescence material (such as a rare earth material), so that the key-shaped layer  62  or the elastomer layer  64  can include the self-luminescence material. 
         [0021]    A print layer  66  may be further disposed at the bottom surface of the elastomer layer  64  to show figures. The print layer  66  is preferred to be light-penetratable to assist the self-luminescence material absorbing light. An elastomer layer  68  may be further disposed under the print layer  66 , which may be a rubber material for example to provide elasticity. A light guide plate  70  is located under the elastomer layer  68  and a light source (not shown) is located on a side or under light guide plate  70 , forming a backlight module to provide light. A light shielding layer  51  is further disposed on the top surface of the elastomer layer  68  to block the light emitted from the backlight module, but expose a portion of the keycap. A plunger  72  is disposed under the light guide plate  70  correspondingly to the position of the key, a dome  56  is disposed under the plunger  72 , and a printed circuit board  58  is disposed under the dome  56 . The dome  56  may be fixed on the printed circuit board  58  by using a dome sheet. Besides, as shown in  FIG. 4 , the elastomer layer  68  and the light guide plate  70  located on the printed circuit board  58  may be bonded together by an adhesive layer  74 . 
         [0022]    In this embodiment, one or both of the key-shaped layer  62  and the elastomer layer  64  are allowed to include the self-luminescence material, as to having self-luminescent properties. Nevertheless, forming an aforementioned self-luminescence material layer located between the key-shaped layer  62  and the elastomer layer  64  or under the elastomer layer  64  is also allowed. Alternatively, the self-luminescence material layer may be coated on the top surface of the key-shaped layer  62  by means of coating. 
         [0023]    Another embodiment according to the present invention is shown in  FIG. 5 . The self-luminescence keycap structure of the self-luminescence keypad structure  80  includes a thin type key-shaped layer  82 , a plastic base film  84  and an elastomer layer  86 , wherein these three members are transparent. The thin type key-shaped layer  82  is formed through a UV-light curing process after application of a UV-light curable resin on the plastic base film  84 . The plastic base film  84  may include a PET material, for example. A print layer  88  can be disposed at the bottom surface of the plastic base film  84  to reveal figures. An elastomer layer  86  is disposed under the print layer  88 , wherein the elastomer layer  86  may be a rubber material for example to provide elasticity. Blending the self-luminescence material in the materials of the thin type key-shaped layer  82 , the plastic base film  84  or the elastomer layer  86  is allowed, to make the thin type key-shaped layer  82 , the plastic base film  84  or the elastomer layer  86  include the self-luminescence material. 
         [0024]    A plunger  90  can be monolithically formed with the elastomer layer  86 . A dome  56  is disposed under the plunger  90  and the printed circuit board  58  is disposed under the dome  56 . Furthermore, the dome  56  is fixed on the printed circuit board  58  by a dome sheet (not shown). The light source  54  is disposed on the printed circuit board  58 . 
         [0025]    In this embodiment, at least one or more of the thin type key-shaped layer  82 , the plastic base film  84  and the elastomer layer  86  is allowed to include the self-luminescence material, as to having self-luminescent properties. However, optionally, an aforementioned self-luminescence material layer  46  may be formed to be located between the plastic base film  84  and the elastomer layer  86  or under the elastomer layer  86 . Alternatively, the self-luminescence material layer can be coated on the top surface of the thin type key-shaped layer  82  by a coating method. 
         [0026]    In another embodiment, the self-luminescence keycap structure is allowed to include a key-shaped layer formed by a lithography process, and the key-shaped layer includes the self-luminescence material, as to having the self-luminescence function. 
         [0027]    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.