Patent Publication Number: US-9412536-B2

Title: Illuminated keyboard

Description:
FIELD OF THE INVENTION 
     The present invention relates to an illuminated keyboard, and more particularly to an illuminated keyboard having a function of sensing whether an object enters a sensing range. 
     BACKGROUND OF THE INVENTION 
     Generally, a keyboard is a peripheral device for inputting characters or commands into an information apparatus such as a desktop computer, a notebook computer, a mobile phone or a tablet computer.  FIG. 1  is a schematic top view illustrating the outer appearance of a conventional keyboard. As shown in  FIG. 1 , there are plural keys  10  on a surface of the conventional keyboard  1 . When one of these keys  10  is depressed by the user&#39;s finger, a corresponding signal is issued to the information apparatus, and thus the information apparatus executes a function corresponding to the depressed key. For example, when the key  101  is depressed, a corresponding English letter or symbol is inputted into the information apparatus. When the key  102  is depressed, a corresponding number is inputted into the information apparatus. When the function key  103  is depressed, a corresponding function is quickly executed. 
     In case that the keyboard is used in a dim environment, the numbers and the characters marked on the keys of the keyboard are not clearly visible. In other words, the dim environment becomes hindrance from operating the keyboard. For solving these drawbacks, an illuminated keyboard has been introduced into the market. 
     Generally, after the conventional illuminated keyboard is manually turned on by the user, a light-emitting element is driven to emit a light beam. Moreover, after the conventional illuminated keyboard is manually turned off by the user, the light-emitting element stops emitting the light beam. As known, the way of manually controlling the illuminating function of the conventional illuminated keyboard is not user-friendly. Moreover, the illuminating function of the illuminated keyboard is usually enabled by the user in the dim environment. However, after the illuminated keyboard is used, the user often forgets disabling the illuminating function of the illuminated keyboard. Consequently, even if the illuminated keyboard is used in a bright environment or the illuminated keyboard is not used by any user, the light-emitting element still emits the light beam. In other words, the use of the conventional illuminated keyboard has the problem of wasting electric power. 
     For solving the above drawbacks, an illuminated keyboard with a proximity sensor is disclosed.  FIG. 2  is a schematic cross-sectional view illustrating an illuminated keyboard with a proximity sensor. This illuminated keyboard  2  is disclosed in Chinese utility model patent Nos. CN201440241. As shown in  FIG. 2 , the illuminated keyboard  2  comprises a keycap layer  21 , a light guide plate  22 , a metal resilience layer  23 , a membrane circuit board  24 , at least one light emitting diode  25 , an induction processing device  26 , an induction antenna  27 , and a keyboard housing  28 . The induction processing device  26  is located at a side of an inner portion of the keyboard housing  28 . The induction antenna  27  is electrically connected with the induction processing device  26 . 
     When a user is located near the illuminated keyboard  2 , the induction processing device  26  senses whether the user enters the sensing range according to the detecting result of the induction antenna  27 . Consequently, the light emitting diode  25  is automatically turned on or turned off. In Chinese utility model patent Nos. CN201440241, the induction antenna  27  is directly printed on the membrane circuit board  24  or circularly disposed within the keyboard housing  28 . In case that the induction antenna  27  is printed on the membrane circuit board  24 , the induction antenna  27  should be separated from the traces of the membrane circuit board  24 . Under this circumstance, the position of installing the induction antenna  27  is restricted. Whereas, in case that the induction antenna  27  is circularly disposed within the keyboard housing  28 , the size of the keyboard housing  28  should be large enough to accommodate the induction antenna  27 . Under this circumstance, the illuminated keyboard fails to meet the requirements of light weightiness, slimness and miniaturization. In the above two situations, since the induction antenna  27  is very close to the metal resilience layer  23 , a signal interference problem occurs. 
     Therefore, there is a need of providing an improved illuminated keyboard with a proximity sensor in order to eliminate the above drawbacks. 
     SUMMARY OF THE INVENTION 
     An object of the present invention provides an illuminated keyboard with a proximity sensor in order to meet the slimness requirement and achieve enhanced induction efficacy. 
     In accordance with an aspect of the present invention, there is provided an illuminated keyboard. The illuminated keyboard includes at least one light-emitting element, a membrane switch circuit module, plural keys, a fixing plate, and a proximity sensor. The at least one light-emitting element provides a light beam to the illuminated keyboard. The membrane switch circuit module generates plural key switch signals. The plural keys are disposed over the membrane switch circuit module. When one of the plural keys is depressed, the membrane switch circuit module generates the corresponding key switch signal. Each of the plural keys includes an elastic element and a keycap connected with the elastic element. The fixing plate is arranged between the membrane switch circuit module and the plural keys. The fixing plate includes plural openings, plural fixing regions, and plural joining regions. The plural openings are disposed under each of the plural keycaps. The plural fixing regions are disposed under the plural keycaps, respectively. Each of the plural fixing regions is arranged between the plural openings under the corresponding keycap so as to fix the corresponding elastic element. Each of the plural fixing regions has a hole, and the corresponding elastic element is penetrable through the hole to push the membrane switch circuit module. The openings between the plural fixing regions are connected with each other through the plural joining regions. The proximity sensor senses whether an object enters a sensing range. The proximity sensor includes an induction antenna circuit. The induction antenna circuit is formed on the plural joining regions or the plural fixing regions of the fixing plate. 
     The above objects and advantages of the present invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic top view illustrating the outer appearance of a conventional keyboard; 
         FIG. 2  is a schematic cross-sectional view illustrating an illuminated keyboard with a proximity sensor; 
         FIG. 3  is a schematic cross-sectional view illustrating an illuminated keyboard according to an embodiment of the present invention; 
         FIG. 4  schematically illustrates a first exemplary induction antenna circuit used in the illuminated keyboard of the present invention; 
         FIG. 5  is a schematic exploded view illustrating a membrane switch circuit module used in the illuminated keyboard of the present invention; 
         FIG. 6  is a schematic perspective view illustrating an illumination circuit board used in the illuminated keyboard of the present invention; and 
         FIG. 7  schematically illustrates a second exemplary induction antenna circuit used in the illuminated keyboard of the present invention. 
         FIG. 8  schematically illustrates a second exemplary induction antenna circuit used in the illuminated keyboard of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Hereinafter, an illuminated keyboard with a proximity sensor according to an embodiment of the present invention will be illustrated with reference to  FIGS. 3 ˜ 6 .  FIG. 3  is a schematic cross-sectional view illustrating an illuminated keyboard according to an embodiment of the present invention.  FIG. 4  schematically illustrates a first exemplary induction antenna circuit used in the illuminated keyboard of the present invention.  FIG. 5  is a schematic exploded view illustrating a membrane switch circuit module used in the illuminated keyboard of the present invention.  FIG. 6  is a schematic perspective view illustrating an illumination circuit board used in the illuminated keyboard of the present invention. It is noted that the structure and the circuit pattern of the illuminated keyboard as shown in  FIGS. 3 ˜ 6  are presented herein for purpose of illustration and description only. 
     In comparison with the conventional illuminated keyboard of  FIG. 2 , the illuminated keyboard  3  of the present invention comprises a fixing plate  31  under plural keys  30 , and plural elastic elements  302  and an induction antenna circuit  321  of a proximity sensor are all disposed on the fixing plate  31 . 
     The components of the illuminated keyboard  3  will be illustrated in more details as follows. Please refer to  FIGS. 3 and 4 . The illuminated keyboard  3  comprises the plural keys  30 , the fixing plate  31 , the proximity sensor, a membrane switch circuit module  33 , a metallic supporting plate  34 , an illumination circuit board  35 , at least one light-emitting element  36 , and a light guide plate  37 . 
     Each of the plural keys  30  comprises a keycap  301 , an elastic element  302 , and a connecting element  303 . The proximity sensor comprises the induction antenna circuit  321  (indicated as oblique lines) and a signal processing unit  322 . The membrane switch circuit module  33  comprises an upper wiring plate  331 , an intermediate plate  332 , and a lower wiring plate  333 . For clarification and brevity, only one key  30  and parts of the fixing plate  31 , the membrane switch circuit module  33 , the metallic supporting plate  34 , the illumination circuit board  35 , the light-emitting element  36  and the light guide plate  37  are shown in  FIG. 3 . 
     The sequence of assembling the illuminated keyboard  3  will be illustrated in more details as follows. The plural keys  30  are disposed over the fixing plate  31 . Both of the elastic element  302  and the connecting element  303  of each key  30  are arranged between the keycap  301  and the fixing plate  31 . The elastic element  302  is fixed or fastened on the fixing plate  31 , and connected with the keycap  301 . The connecting element  303  is connected with the keycap  301  and the metallic supporting plate  34 . In this embodiment, the connecting element  303  is a scissors-type connecting element, but is not limited thereto. An example of the fixing plate  31  includes but is not limited to a polyethylene terephthalate (PET) film. 
     Please refer to  FIG. 4  again. In accordance with the features of the illuminated keyboard  3 , the fixing plate  31  comprises plural openings  311 , plural joining regions  312  and plural fixing regions  313 ; the plural elastic elements  302  of the plural keys  30  are fixed or fastened on the plural fixing regions  313  and the induction antenna circuit  321  (indicated as oblique lines) of the proximity sensor are formed on the plural joining regions  312 . These features will be illustrated as follows. 
     Firstly, some of the plural openings  311  are formed in the portion of the fixing plate  31  under the corresponding keycap  301 . A first fixing structure  341  and a second fixing structure  342  of the metallic supporting plate  34  are penetrated through the corresponding openings  311  of the fixing plate  31 , and then connected with the connecting element  303  corresponding to the keycap  301 . 
     Each of the plural fixing regions  313  is located at the portion of the fixing plate  31  under the corresponding keycap  30 . In addition, the fixing region  313  is arranged between the openings  311  corresponding to the keycap  301  in order to fix the elastic element  302  corresponding to the keycap  301 . Moreover, one joining region  312  is arranged between every two adjacent fixing regions  313 . Through the joining region  312 , the openings  311  between every two adjacent fixing regions  313  are connected with each other. 
     Then, as shown in  FIG. 4 , a sensing part  3211  of the induction antenna circuit  321  (indicated as oblique lines) is arranged between two adjacent rows of fixing regions  313 . Moreover, plural connecting parts  3212  of the induction antenna circuit  321  (indicated as oblique lines) are also formed on the joining regions  312 . Through the plural connecting parts  3212 , the plural sensing parts  3211  are electrically connected with each other. 
     In this embodiment, the induction antenna circuit  321  (indicated as oblique lines) is a silver paste conductive line that is formed on the fixing plate  31  by a screen printing process, but is not limited thereto. In this embodiment, the induction antenna circuit  321  is formed on a top surface of the fixing plate  31 . It is noted that the position of the induction antenna circuit  321  shown in the drawings is presented herein for purpose of illustration and description only. Alternatively, the induction antenna circuit  321  may be formed on a bottom surface of the fixing plate  31 . 
     Then, the membrane switch circuit module  33  is disposed under the fixing plate  31 . Please refer to  FIG. 5 . A first circuit pattern  3311  is formed on a bottom surface of the upper wiring plate  331 . The first circuit pattern  3311  comprises plural upper contacts  3311   a . A second circuit pattern  3331  is formed on a top surface of the lower wiring plate  333 . The second circuit pattern  3331  comprises plural lower contacts  3331   a  corresponding to the plural upper contacts  3311   a . Each of the upper contacts  3311   a  and the corresponding lower contact  3331   a  are collaboratively defined as a membrane switch  334 . In addition, each membrane switch  334  is aligned with a corresponding key  30 . 
     The intermediate plate  332  is arranged between the upper wiring plate  331  and the lower wiring plate  333  for separating the upper wiring plate  331  and the lower wiring plate  333  from each other. Consequently, each of the upper contacts  3311   a  and the corresponding lower contact  3331   a  are separated from each other by a spacing distance. In addition, the intermediate plate  332  has plural perforations  3321  corresponding to the plural upper contacts  3311   a.    
     When one of the keycaps  301  is depressed, the keycap  301  is moved downwardly with the assistance of the connecting element  303 . At the same time, the elastic element  302  is compressed by the keycap  301  and thus subject to deformation. Consequently, a protrusion part  3021  within the elastic element  302  is moved downwardly to push the membrane switch circuit module  33 . Under this circumstance, the upper contact  3311   a  of the membrane switch  334  corresponding to the depressed keycap  301  is penetrated through the corresponding perforation  3321  and contacted with the corresponding lower contact  3331   a . Consequently, the membrane switch circuit module  33  generates a corresponding key switch signal. According to the key switch signal, a corresponding function (e.g. a function of inputting a character, a symbol or a number into a computer system) is executed by the illuminated keyboard  3 . 
     Moreover, the plural fixing regions  313  of the fixing plate  31  comprise plural holes  314 , respectively. Consequently, the protrusion part  3021  within the elastic element  302  may be penetrated through the corresponding hole  314  of the fixing plate  31  to push the membrane switch circuit module  33 . 
     Moreover, the metallic supporting plate  34  is disposed under the membrane switch circuit module  33  for enhancing the overall structural strength of the illuminated keyboard  3  and fixing the plural connecting element  303  of the plural keys  30 . In this embodiment, the metallic supporting plate  34  is an iron plate, but is not limited thereto. 
     The connecting element  303  of each key  30  comprises a first frame  3031  and a second frame  3032 . The first frame  3031  is pivotally coupled to the second frame  3032 . In addition, the first frame  3031  and the second frame  3032  intersect each other. Two ends of the first frame  3031  are connected to an inner surface of the keycap  301  and the first fixing structure  341  of the metallic supporting plate  34 , respectively. Two ends of the second frame  3032  are connected to the inner surface of the keycap  301  and the second fixing structure  342  of the metallic supporting plate  34 . Moreover, the first fixing structure  341  and the second fixing structure  342  of the metallic supporting plate  34  are penetrated through the membrane switch circuit module  33  and the fixing plate  31 , and exposed over the fixing plate  31 . 
     Then, the light guide plate  37  is disposed under the metallic supporting plate  34 . The light guide plate  37  is made of a transparent light-guiding material with low absorptivity and high refractivity to the light beam. An example of the transparent light-guiding material includes but is not limited to polycarbonate (PC), polymethylmethacrylate (PMMA), polyethylene terephthalate (PET) or silicone. 
     Afterwards, the illumination circuit board  35  is disposed under the light guide plate  37 . In addition, the at least one light-emitting element  33  and the signal processing unit  322  are both disposed on the illumination circuit board  35 , and electrically connected with the illumination circuit board  35  (see  FIG. 6 ). It is noted that the shape of the illumination circuit board  35 , the number and the position of the at least one light-emitting element  33  and the position of the signal processing unit  322  shown in the drawings are presented herein for purpose of illustration and description only. Moreover, an example of the illumination circuit board  35  includes but is not limited to a printed circuit board (PCB) or a flexible printed circuit (FPC). 
     Moreover, the signal processing unit  322  is electrically connected with the induction antenna circuit  321  by a thermal bonding process, but is not limited thereto. For example, in the thermal bonding process, the induction antenna circuit  321  and the signal processing unit  322  are connected with each other by an anisotropic conductive film (ACF). It is noted that the way of connecting the induction antenna circuit  321  and the signal processing unit  322  is not restricted. 
     The signal processing unit  322  may be penetrated through the fixing plate  31 , the membrane switch circuit module  33 , the metallic supporting plate  34  and the light guide plate  37 , and received within the region under the keycap  301  of a specified key with a larger width (e.g. the keycap  301  of a space bar). 
     The light-emitting element  36  may be penetrated through the light guide plate  37 . Consequently, the light beam from the light-emitting element  36  is laterally introduced into the light guide plate  37 . The light beam from the light-emitting element  36  is transferred by the light guide plate  37 , so that the light beam is diffused to the regions under all of the plural keys  30 . 
     Hereinafter, the operating principles of the illuminated keyboard  3  of this embodiment will be illustrated in more details. In this embodiment, the proximity sensor is a capacitive sensor. When the illumination circuit board  35  is electrically conducted, an induction electric field is generated by the induction antenna circuit  321 . Moreover, when an object (e.g. a human body) is located near the induction electric field, the induction electric field is subject to a change. According to the change of the induction electric field, the signal processing unit  322  electrically connected with the induction antenna circuit  321  may judge that the object enters a sensing range. Consequently, the signal processing unit  322  issues a sensing signal. 
     After the sensing signal from the signal processing unit  322  is received by the illuminated keyboard  3 , a controlling unit (not shown) of the illuminated keyboard  3  drives illumination of the light-emitting element  36  in response to the sensing signal. Consequently, the illuminating function of the illuminated keyboard  3  is enabled. Moreover, in response to the sensing signal, the controlling unit of the illuminated keyboard  3  may issue a command to a computing device that is connected with the illuminated keyboard  3 . According to the command, the computing device is waked up from a sleep mode or a hibernation mode. An example of the computing device includes but is not limited to a desktop computer or a notebook computer. 
     When the object is far away from the induction electric field, which is generated by the induction antenna circuit  321 , the object is no longer within the sensing range. Meanwhile, the induction electric field is also subject to a change. According to the change of the induction electric field, the signal processing unit  322  will notify the controlling unit of the illuminated keyboard  3  to stop driving illumination of the light-emitting elements  36 . Under this circumstance, the illuminating function of the illuminated keyboard  3  is disabled. In other words, by judging whether the user enters the sensing range of the illuminated keyboard  3 , the illuminating function of the illuminated keyboard  3  can be automatically enabled or disabled. 
       FIGS. 7 and 8  schematically illustrate a second exemplary induction antenna circuit used in the illuminated keyboard of the present invention. The induction antenna circuit  321  is replaced by the induction antenna circuit  421  of  FIG. 7 . The second exemplary induction antenna circuit  421  comprises eight sensing parts, including four sensing parts  4211   a  and four sensing parts  4211   b . The four sensing parts  4211   a  are formed on the fixing region  313  of the fixing plate  31  under a specified keycap  301   a  and the joining regions  312  at bilateral sides of this fixing region  313  as shown in  FIG. 8 . 
     Moreover, two of the four sensing parts  4211   b  of the induction antenna circuit  421  are formed on the fixing region  313  of the fixing plate  31  which is under another specified keycap  301   b , and the other two of the four sensing parts  4211   b  are formed on the fixing region  313  of the fixing plate  31  which is under another specified keycap  301   c . In this embodiment, the induction antenna circuit  421  is formed on a top surface of the fixing plate  31 . Alternatively, in some other embodiments, the fixing plate  31  is formed on a bottom surface of the fixing plate  31 . 
     In this embodiment, the keycap  301   a  is a keycap of a space bar, but is not limited thereto. The keycap  301   b  is a keycap of a Shift key, and the keycap  301   c  is a keycap of an Enter key, but is not limited thereto. 
     From the above descriptions, by the proximity sensor of the illuminated keyboard of the present invention, the illuminating function of the illuminated keyboard is automatically enabled or disabled. Moreover, since the induction antenna circuit is formed on the fixing plate, the layout area of the induction antenna circuit increases. Moreover, since the induction antenna circuit is far from the metallic supporting plate, the possibility of causing the signal interference problem will be minimized. In addition, the illuminated keyboard can meet the requirements of light weightiness, slimness and miniaturization. 
     While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.