Patent Publication Number: US-2009237577-A1

Title: Electronic device and input device thereof

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to an input device for electronic devices. 
     2. Description of Related Art 
     Input devices, such as keyboards and touchscreens are widely used for inputting information into microprocessors or other similar semiconductor circuits. There are several types of keyboards available, such as mechanical keyboards, membrane/film keyboards, and virtual keyboards. 
     A mechanical keyboard adopts an individual keyswitch mechanism for each key. However, to generate a keystroke, more force is needed to actuate the mechanical key than using the membrane keyboards. This may result in carpal tunnel syndrome for the user&#39;s wrists after an extended period of use of the mechanical keyboard. Furthermore, most mechanical keys generate a clicking sound when the key is actuated, and this may disturb others in close quarters. 
     Membrane keyboards are by far the most commonly used with computers and all kinds of portable electronic devices. They are designed so that all keycaps are positioned above rubber domes. Each rubber dome is above a  3 -layer plastic membrane that spreads over the entire keyboard. The membrane keyboards produce no audible click when pressed, and need a lighter touch than mechanical keyboards. However, some keys become inelastic and other overly elastic because of buildup of debris, rubber fatigue, manufacturing imperfections and even ultraviolet radiation after a long time use. This creates a variance in how much force is required to actuate each key on the keyboard. 
     A touchscreen is a display which can detect the presence and location of a touch within the display area. Touchscreens can also sense other passive objects, such as a stylus. As input devices, the touchscreens do not have the aforementioned deficiency and inadequacies in the mechanical keyboards and membrane keyboards. However, new type input devices are also desired. 
     Therefore, it is desired to provide a new input device having similar figure and advantages of a touchscreen. 
     Other advantages and novel features of the present invention will become more apparent from the following detailed description of an embodiment/embodiments when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an electronic device in accordance with an exemplary embodiment, the electronic device includes an input device having a plurality of keys. 
         FIG. 2  is a block diagram of one of the plurality of keys of  FIG. 1  in accordance with a first exemplary embodiment. 
         FIG. 3  is a schematic circuit diagram of one of the plurality of keys of  FIG. 1 . 
         FIG. 4  is a block diagram of a key in an input device in accordance with a second exemplary embodiment. 
         FIG. 5  is a block diagram of an input device in accordance with a third exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 , an electronic device  100  in accordance with an exemplary embodiment includes a display  10 , an input device  20 , and a control unit  30 . The electronic device  100  is shown as a mobile phone in  FIG. 1 , however, it may also be an automatic teller machine (ATM), a computer, a personal digital assistant, or a navigation device, etc. 
     The display  10  is configured for displaying information. 
     The input device  20  includes a plurality of keys  21  for receiving pressing operations and generating first electrical signals correspondingly. The input device  20  further includes a decoder  40  for decoding the first electrical signals, and generating second electrical signals corresponding to the first electrical signals. The first electrical signals generated by each of the plurality of keys  21  are the same, while the second electrical signals generated by the decoder  40  are different according to the plurality of keys  21 . The second electrical signals are recognizable by the control unit  30 , and are used for identifying each of the plurality of keys  21 . In the embodiment, each of the plurality of keys  21  has a similar structure. Thus, only one of the plurality of keys  21  is described below. 
     The key  21  includes seven layers and a light source  17 . The seven layers include a first insulation layer  22 , a second insulation layer  12 , a first conductive film  13 , a second conductive film  14 , a liquid crystal layer  15 , a light transmitting layer  16 , and a photoelectric transforming layer  18 . 
     The first insulation layer  22  is disposed on top of the key  21  as a touch layer. The first conductive film  13 , the photoelectric transforming layer  18 , the liquid crystal layer  15 , the second conductive film  14 , the light transmitting layer  16 , and the second insulation layer  12  are disposed underneath the first insulation layer  22  in a sequential order. 
     The first and second insulation layers  22 ,  12  may be made of colophony, plastic, glass, or rubber material. In the embodiment, the first insulation layer  22  is made of opaque colophony material, such that external light cannot be transmitted into the key  21 . There are one or more key identification characters, such as “1” or “select”, engraved or printed on the first insulation layer  22 . 
     The first conductive film  13  is configured for cooperating with the second conductive film  14  to generate an electric field with a voltage applied thereto. When the key  21  is fully pressed, a first electric field having a first predetermined intensity is generated. When the key  21  is not pressed or released, a second electric field having a second predetermined intensity is generated. The second predetermined intensity of the second electric field is lower than the first predetermined intensity of the first electric field. The first conductive film  13  and the second conductive film  14  may be both coated with a conductive material (for example, indium tin oxide material, ITO material) that conducts a continuous electrical current across the films. It is known that not only can the ITO material conduct electrical current, but also is transparent to light. 
     The light source  17  is disposed adjacent to the light transmitting layer  16 . The light source  17  may be any type of mini-light sources, such as a light-emitting diode (LED). The light transmitting layer  16  includes one or more light conduits  161  (refer to  FIG. 3 ) for transmitting light emitted from the light source  17  through the second conductive film  14  to the liquid crystal layer  15 . Thus, the second conductive film  14  should be transparent. The liquid crystal layer  15  may be made of any type of liquid crystal molecule, such as twisted nematic (TN), super twisted nematic (STN), or dual scan tortuosity nomograph (DSTN) molecule. The liquid crystal layer  15  is configured for transmitting light from the light source  17  to the photoelectric transforming layer  18  under the influence of the first electric field. The second predetermined intensity of the second electric field is not enough to influence the liquid crystal layer  15  to transmit light. The photoelectric transforming layer  18  is configured for transforming light to generate the first electric signal when receiving light from the liquid crystal layer  15 . 
     Referring also to  FIG. 3 , the photoelectric transforming layer  18  may include at least a photoelectric transformer  181 , such as a phototransistor. In the embodiment, the photoelectric transforming layer  18  includes a phototransistor (also labeled as  181 ). An emitter of the phototransistor  181  is grounded, a collector of the phototransistor  181  is connected to a power supply VCC via a resistor  182 . The collector of the phototransistor  181  is also connected to the decoder  40 . 
     During operation, when the key  21  is not pressed, light emitted by the light source  17  is blocked by the liquid crystal layer  15  and is not transmitted to the phototransistor  181 . The phototransistor  181  is off and the voltage at the decoder  40  is VCC. The decoder  40  has no output, or an output of the decoder  40  is not changed. When the key  21  is pressed, the first conductive film  13  moves closer to the second conductive film  14  and at a predetermined distance between the first and second conductive films  13 ,  14 , the second electric field is increased to the first predetermined intensity. The liquid crystal layer  15  is influenced by the first electric field to transmit light. Thus, light emitted by the light source  17  travels to the phototransistor  181  via the liquid crystal layer  15 . As a result, the phototransistor  181  is turned on, and a voltage at the collector of the phototransistor  181  is pulled to ground. Thus, the decoder  40  is at  0  volts, and the decoder generates the second electric signal that is recognizable by the control unit  30 . 
     The control unit  30  is configured for controlling the information that is displayed on the display  10 , powering the input device  20 , and receiving and processing the second electric signal(s) according to predetermined programs. The first and second conductive films  13 ,  14 , and the light source  17  may be connected to and powered by the control unit  30 . The control unit  30  may supply a first predetermined voltage to the first and second conductive films  13 ,  14 , so as to generate the second electric field having the second predetermined intensity. 
     To sum up, the key  21  is actuated by pressing the first insulation layer  22  to push the first conductive film  13  toward the second conductive film  14 . This will produce no audible click, and requires a force that is lighter than that of mechanical keys. 
     In the embodiment, the plurality of keys  21  may contain separate liquid crystal layers  15  and photoelectric transforming layer  18  for individual keys  21 , but other layers of the seven layers of the plurality of keys  21  may form essentially uniform layers. In other words, the plurality of keys  21  may share a piece of the first insulation layer  22 , a piece of the second insulation layer  12 , a piece of the first conductive film  13 , a piece of the second conductive film  14 , and a piece of the light transmitting layer  16 . For example, a first key of the plurality of keys  21  may utilize a first section of the first insulation layer  22 , a first section of the second insulation layer  12 , a first section of the first conductive film  13 , a first section of the second conductive film  14 , and a first section of the light transmitting layer  16 . And a second key of the plurality of keys  21  may utilize a second section of the first insulation layer  22 , a second section of the second insulation layer  12 , a second section of the first conductive film  13 , a second section of the second conductive film  14 , and a second section of the light transmitting layer  16 . Other layers may be shared in a similar manner. Thus, the input device  20  can be easily integrated to form a part of a casing of the electronic device  100 . Furthermore, the input device  20  is useful particularly in applications where the electronic device  100  and the input device  20  must be inside a compact casing in order to be water or dust resistance, for instance. 
     In other embodiments, the input device  20  may only include one or more light sources  17 . Light emitted by the one or more light sources  17  travels to the plurality of keys  21  via the light transmitting layer  16 . The first insulation layer  22  may be transparent or semitransparent, and the position of the one or more key identification characters on the first insulation layer  22  coincides with the position of the photoelectric transformer  181 , such that external light is blocked by the one or more characters and cannot travel to the photoelectric transformer  181 . 
     In other embodiments, positions of the photoelectric transforming layer  18  and the first conductive film  13  can be exchanged, and positions of the light transmitting layer  16  and the second conductive film  14  can be exchanged. The input device  20  may further include another light transmitting layer, disposed between the photoelectric transforming layer  18  and the liquid crystal layer  15 . The another light transmitting layer is configured for transmitting light from the liquid crystal layer  15  to corresponding photoelectric transformer  181  of the photoelectric transforming layer  18 . In other embodiments, the input device  20  may include only one key  21 . 
     Referring to  FIG. 4 , a key  211  of an input device in accordance with a second exemplary embodiment is illustrated. Similar to the key  21 , the key  211  includes the seven layers and the light source  17 . The seven layers include the first insulation layer  22 , the light transmitting layer  16 , the first conductive film  13 , the liquid crystal layer  15 , the second conductive film  14 , the photoelectric transforming layer  18 , and the second insulation layer  12  which are disposed in a sequential order. 
     In the embodiment, the first insulation layer  22 , the first conductive film  13 , and the second conductive film  14  are transparent. There is no key identification character(s) engraved or printed on the first insulation layer  22 . The key identification character(s) is (are) displayed by the liquid crystal layer  15 . Thus, an appearance of the key  211  may be more appealing or attractive than that of the key  21 . Position of the key identification character(s) displayed and position of the photoelectric transformer  181  of the photoelectric transforming layer  18  are staggered, such that the photoelectric transformer  181  is not turned on by the light of the key identification character(s). 
     Similar to the key  21 , the key  211  is actuated, that is, the first electric signal is generated, when the key  211  is pressed. When the key  211  is not pressed, light emitted by the light source  17  is blocked by the liquid crystal layer  15  and cannot travel to the photoelectric transformer  181 . There is no first electric signal, and the output of the decoder  40  is unchanged, that is, VCC. 
     In alternative embodiments, the positions of the photoelectric transforming layer  18  and the second conductive film  14  can be exchanged, and the positions of the light transmitting layer  16  and the first conductive film  13  can be exchanged. The key  211  may further include another light transmitting layer, disposed between the photoelectric transforming layer  18  and the liquid crystal layer  15 , for transmitting light from the liquid crystal layer  15  to corresponding photoelectric transformer  181  of the photoelectric transforming layer  18 . 
     Conventionally, a liquid crystal display (LCD) also has two conductive films/layers similar to the first and second conductive films  13 ,  14 , and a liquid crystal layer similar to the liquid crystal layer  15 . Thus, when the display  10  is the LCD display, the display  10  and the input device  20 , the two conductive films/layers, and the liquid crystal layer of the display  10  may be integrated together. The LCD display may also have one or more light source and a light emitting transmitting layer for backlighting. Thus the display  10  and the input device  20  may share the light source  17 , and the light transmitting layer  16 . The second insulation layer  12  may also be shared by the display  10  and the input device  20  (see  FIG. 5 ). The display  10  may also include a third insulation layer  11  as a protection layer disposed on top of the display  10 . As a result, the display  10  and the input device  20  may be integrated together. 
     It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.