Abstract:
An optical keyboard includes a key assembly for alphanumeric data input; a keyboard housing being an integrally formed rectangular block for surrounding the key assembly, the keyboard housing including a left frame member, a right frame member, a rear frame member, and a front frame member; and at least one actuation sensing module disposed on a periphery of the keyboard housing, each of the at least one actuation sensing module including a light emitting member for emitting light directed to a predetermined space above the key assembly within the keyboard housing to create a sensing zone, and a photo sensor for sensing light emitted from the light emitting member.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to optical keyboards and more particularly to an optical keyboard capable of toggling between an operating mode of pressing key and an operating mode of a key to be touched. 
         [0003]    2. Description of Related Art 
         [0004]    Touchscreen is an electronic visual display that can detect the presence and location of a touch within the display area. Touchscreens are common in devices such as game consoles, all-in-one computers, tablet computers, and smartphones. 
         [0005]    They are a variety of touchscreen technologies that have different methods of sensing touch. These technologies include resistive, surface acoustic wave (SAW), capacitive, surface capacitance, projected capacitance, mutual capacitance, self-capacitance, infrared grid, infrared acrylic projection, optical imaging, dispersive signal technology, and acoustic pulse recognition. 
         [0006]    A conventional optical keyboard comprises a keyboard housing having a matrix of rows and columns of apertures for keys, the housing having recesses open to the top of the keyboard between the apertures; and a plurality of keys for positioning in the apertures of the keyboard housing, each of the keys having an umbrella shaped cap with edges extending over the recesses between the apertures, whereby liquid and debris spilling on the umbrella shaped cap will fall into the recesses to be contained. 
         [0007]    The conventional optical keyboard has been successfully used in a commercial application. However, its construction is complicated and cost ineffective. Thus, the need for improvement still exists. 
       SUMMARY OF THE INVENTION 
       [0008]    It is therefore one object of the invention to provide an optical keyboard comprising a key assembly for alphanumeric data input; a keyboard housing being an integrally formed rectangular block for surrounding the key assembly, the keyboard housing including a left frame member, a right frame member, a rear frame member, and a front frame member; and at least one actuation sensing module disposed on a periphery of the keyboard housing, each of the at least one actuation sensing module including a light emitting member for emitting light directed to a predetermined space above the key assembly within the keyboard housing so as to create a sensing zone, and a photo sensor for sensing light emitted from the light emitting member. 
         [0009]    The above and other objects, features and advantages of the invention will become apparent from the following detailed description taken with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a perspective view of an optical keyboard according to a first preferred embodiment of the invention; 
           [0011]      FIG. 2  is a sectional view taken along line A-A of  FIG. 1  showing a finger in the sensing zone detected by the actuation sensing module when the finger is about to press a key; 
           [0012]      FIG. 3  is a view similar to  FIG. 2  showing a further descending of the finger with the tip of the finger being about at the same elevation of the actuation sensing module;  FIG. 4  is a top view of  FIG. 1  showing different light reflection paths in the sensing zone in response to movement of the finger; 
           [0013]      FIG. 5  is a block diagram of the optical keyboard according to the first preferred embodiment of the invention; 
           [0014]      FIG. 6  is a perspective view of an optical keyboard according to a second preferred embodiment of the invention showing a key actuation sensing arrangement being provided on inner surfaces of a rectangular keyboard housing in the numeric keypad of the key assembly; 
           [0015]      FIG. 7  is a view similar to  FIG. 6  showing a touch panel being provided as a replacement of the numeric keypad of the key assembly in another configuration of the second preferred embodiment of the invention; 
           [0016]      FIG. 8  is a perspective view of an optical keyboard according to a third preferred embodiment of the invention showing the actuation sensing modules provided on vertexes of a virtual triangle of a keyboard housing respectively; and 
           [0017]      FIG. 9  is a front view of the optical keyboard of  FIG. 8  showing the hand being in the sensing zone in a key actuation operation. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    Referring to  FIGS. 1 to 5 , an optical keyboard in accordance with a first preferred embodiment of the invention comprises a key assembly  10 , a keyboard housing  20 , and two actuation sensing modules  30  as discussed in detail below. 
         [0019]    The key assembly  10  comprises a plurality of keys  11  for input, a plurality of scissor-type structures  12 , a film circuit board  13 , and a base board  14 . The key  11  is adapted to press and pivotably mounted on top of the scissor-type structure  12 . The scissor-type structure  12  is a pivotal element and pivotably mounted on top of the base board  14 . The film circuit board  13  disposed between the scissor-type structures  12  and the base board  14  serves as a conductive element in response to a depressing of the key  11 . The base board  14  is a support under the film circuit board  13 . Alternatively, the key assembly  10  is replaced with a touchscreen or a planar electronic input device in other embodiments. 
         [0020]    The keyboard housing  20  is an integrally formed rectangular block for surrounding the key assembly  10 . The keyboard housing  20  comprises a left frame member  201 , a right frame member  202 , a rear frame member  203 , and a front frame member  204 . A plurality of reflective members  21  are disposed on inner surfaces of the left frame member  201 , the right frame member  202 , and the rear frame member  203  respectively. The reflective members  21  are adapted to generate signals when light impinged thereon being blocked. 
         [0021]    The actuation sensing modules  30  are disposed on both ends of the front frame member  204  of the keyboard housing  20  respectively. The actuation sensing module  30  comprises a photo sensor  301  for optically detecting an object (e.g., a finger) about to actuate the key  11 , and a light emitting member  302  (e.g., light-emitting diode (LED)) for emitting red light. Preferably, the emitted light is invisible light such as infrared or ultra infrared in order not to be interfered by visible light. Light emitted by the light emitting members  302  is directed to a predetermined space above the keys  11  within the rectangular keyboard housing  20  to create a sensing zone. Light received by the photo sensors  301  is partially blocked when a finger is descending into the sensing zone to actuate a key  11 . Strength of the light is thus decreased due to the blocking. Further, a signal is created by the photo sensors  301  due to changes of horizontal distance, vertical distance, and light angle, etc. The created signal is sent to a signal processing unit  33  for processing in order to determine whether the finger is sliding or about to press the key  11 . Finally, a signal representing a key to be touched instruction containing a corresponding coordinate is created. Preferably, the photo sensor  301  is a complementary metal oxide semiconductor (CMOS) and has a wide angle image taking capability. The number and locations of the actuation sensing modules  30  can be changed based on the required image resolution. For example, in other embodiments, the photo sensors  301  are disposed in four corners of an inner surface of the keyboard housing  20  respectively in order to accurately detect the position of the finger touching the key  11  and carry out a multi-touch scheme. 
         [0022]    As shown in  FIG. 5  specifically, the optical keyboard further comprises a switch unit  50 , a signal sensing unit  40 , and a signal output unit  60  as discussed in detail below. 
         [0023]    The signal sensing unit  40  is electrically connected to the key assembly  10  and the signal processing unit  33  and adapted to determine a signal representing the depressed key  11  and a signal representing a key to be touched instruction containing a corresponding coordinate. 
         [0024]    The switch unit  50  is electrically connected to the signal sensing unit  40  and adapted to toggle between an operating mode of pressing key and an operating mode of a key to be touched. The signal sensing unit  40  is responsive to a key depressing signal when the switch unit  50  is toggled to the operating mode of pressing key. Further, a signal representing the depressed key  11  is generated by the signal sensing unit  40  and transmitted to the signal output unit  60 . To the contrary, the signal sensing unit  40  is responsive to a key to be touched signal when the switch unit  50  is toggled to the operating mode of a key to be touched. Further, a signal representing the key  11  to be touched is generated by the signal sensing unit  40  and transmitted to the signal output unit  60 . 
         [0025]    The signal output unit  60  is electrically connected to the signal sensing unit  40 , adapted to receive either the signal representing the depressed key  11  or the signal representing the key  11  to be touched, and send the signal to a computer  70 . The computer  70  can process the signal representing the depressed key  11  or the signal representing the key  11  to be touched and generate a corresponding character to be shown on a computer display. The signal output unit  60  is implemented as a wireless Bluetooth adapter or a wire universal serial bus (USB) adapter. Above electronic devices are powered by a battery (not shown) and detailed description thereof is omitted herein for the sake of brevity because they are well known in the art. 
         [0026]    Referring to  FIGS. 6 and 7 , an optical keyboard in accordance with a second preferred embodiment of the invention is shown. The characteristics of the second preferred embodiment are substantially the same as that of the first preferred embodiment except the following: The sensing zone is disposed above a numeric keypad of the key assembly  10 . In detail, a rectangular keypad housing  20 A is provided in the numeric keypad of the key assembly  10  (see  FIG. 6 ) or a touch panel  101  is provided in the keypad housing  20 A as a replacement of the numeric keypad of the key assembly  10 . A plurality of reflective members  21 A are disposed on an inner surface of the keyboard a rectangular keypad housing  20 A is provided on the numeric keypad of the key assembly  10  (see  FIG. 6 ) or a touch panel  101  is provided a in the keypad housing  20 A as a replacement of the numeric keypad of the key assembly  10 . A plurality of reflective members  21 A are disposed on an inner surface of the keypad housing  20 A and two actuation sensing modules  30 A are disposed on both ends of a front edge the keypad housing  20 A respectively. Light emitted by the actuation sensing modules  30 A is directed to a predetermined space above the keys  11  within the keypad housing  20 A to create a sensing zone. The actuation sensing modules  30 A are adapted to optically detect an object (e.g., finger) about to actuate the key  11  below the sensing zone and next generating a signal representing a key to be touched instruction containing a corresponding coordinate. 
         [0027]    Referring to  FIGS. 8 and 9 , an optical keyboard in accordance with a third preferred embodiment of the invention is shown. The characteristics of the third preferred embodiment are substantially the same as that of the first preferred embodiment except the following: Three actuation sensing modules  30  are disposed at three vertexes of a virtual triangle on the keyboard housing  20 . In detail, the actuation sensing modules  30  are disposed at both ends of the front frame member  204  and a midpoint of the rear frame member  203  respectively in order to accurately detect the position of the finger touching the key and carry out a multi-touch scheme. 
         [0028]    While the invention has been described in terms of preferred embodiments, those skilled in the art will recognize that the invention can be practiced with modifications within the spirit and scope of the appended claims.