Abstract:
A keyboard or keypad which can highlight symbols on the keys by illuminating them. The keys are backlit by two light sources, one visible and one ultraviolet, each of which illuminates multiple keys. One symbol on each key is designed to transmit the visible light, becoming highlighted when the visible light source is activated. A second symbol on each key is designed to fluoresce when illuminated by ultraviolet light, becoming highlighted when the ultraviolet light source is activated. If desired, both light sources can be activated, highlighting both symbols simultaneously. If desired, complementary light color and filter material may be used to reduce or eliminate transmission of light through the second symbol. A single pair of light sources may be used for the entire keyboard or the keyboard may be divided into segments with separate light sources for each segment.

Description:
BACKGROUND 
       [0001]    Electronic devices presently on the market are more frequently providing keyboards or keypads which support alternate input functions such as key chording, multiple input methods, different physical orientations, etc. This results in part from devices becoming physically smaller while at the same time they are adding support for additional functionality. 
         [0002]    Typically these alternate input functions are indicated through the use of additional symbols on the keys. As a result, the keys on these devices are often difficult to read. One reason is the visual clutter which results from having multiple symbols on each key and crowding the keys closer together. Another reason is that the size of the symbols themselves are reduced to allow them to fit on the keys. These problems are compounded as smaller devices drive the use of smaller keys. Even when the symbols can be read, there may be user confusion as to which set of symbols is applicable to the function for which the device is currently being used. 
         [0003]    It is helpful to visually emphasize one set of symbols over the others so that the appropriate set of symbols is more readily apparent to the user. One method of doing so is to illuminate the set of symbols which is to be emphasized. 
         [0004]    One method of providing for separate illumination of separate symbols sets is to provide discrete illumination for each symbol on each key. The illumination may be a separate light source, such as an LED, or a light pipe which directs light from a remote source to the key. Both approaches require a separate physical device (i.e. LED or light pipe) for each symbol requiring illumination. With plural symbols per key, this results in a greater number of light sources than there are keys on the keyboard. Of necessity, these light sources must be smaller than the keys themselves, at least at the interface to the key. Where the light source is relatively bulky, it limits how small the device can be made. Where the light source can be made sufficiently small to not drive the size of the device larger, the light source may become fragile due to reduced component sizes. Light sources capable of providing the requisite lighting levels on an individual key basis may also consume a large amount of the available power relative to the rest of the device. 
         [0005]    Exemplary devices to which the present disclosure is relevant include computer keyboards; calculator keypads; remote controls for televisions and stereos; kitchen appliances such as microwave ovens; mobile communication devices and PDAs; mobile and automotive media player devices; and converged mobile devices which combine two or more of these functions. 
       SUMMARY 
       [0006]    This Summary is provided to introduce in a simplified form a selection of concepts that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. 
         [0007]    Various aspects of the subject matter disclosed herein are related to illuminating the keys of a keyboard or keypad from behind with two separately controllable light sources: one visible, and one ultraviolet. At least some keys on the keyboard will have two different symbols. One will be designed to transmit the visible light. The other will be designed to fluoresce when illuminated by the ultraviolet light source. 
         [0008]    Other aspects relate to using a colored light source and a complementary colored filter in the symbols which fluoresce when exposed to ultraviolet light. This blocks, or substantially reduces the amount of visible light transmitted by those symbols. 
         [0009]    Still other aspects of the invention relate to dividing the keyboard into distinct segments and providing separate visible and ultraviolet light sources for each so that the keys making up a segment can be separately highlighted. 
         [0010]    A more complete appreciation of the above summary can be obtained by reference to the accompanying drawings, which are briefly summarized below, to the following detailed description of present embodiments, and to the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0011]      FIG. 1  illustrates an exemplary keyboard with certain keys having plural symbol sets. 
           [0012]      FIG. 2A  is a detailed view of a segment of the keyboard of  FIG. 1  illustrating an exemplary set of keys having plural symbol sets. 
           [0013]      FIG. 2B  is a detailed view of a single key shown in  FIG. 2A . 
           [0014]      FIG. 3A  is a detailed view of a segment of the keyboard of  FIG. 1  illustrating an exemplary set of keys having plural symbol sets with a first set of symbols illuminated. 
           [0015]      FIG. 3B  is a detailed view of a single key shown in  FIG. 3A . 
           [0016]      FIG. 4A  is a detailed view of a segment of the keyboard of  FIG. 1  illustrating an exemplary set of keys having plural symbol sets with a second set of symbols illuminated. 
           [0017]      FIG. 4B  is a detailed view of a single key shown in  FIG. 4A . 
           [0018]      FIG. 5  is a cross section through the key illustrated in  FIG. 2B   
           [0019]      FIG. 6  is a cross section through the key illustrated in  FIG. 2B  showing an exemplary filter layer. 
           [0020]      FIG. 7  illustrates an exemplary LED array for illuminating a keyboard having a layout as shown in  FIG. 1 . 
           [0021]      FIG. 8  illustrates an exemplary LED array for illuminating a keyboard having a layout as shown in  FIG. 1 , with separate lighting capability for the numeric keypad segment. 
           [0022]      FIG. 9  illustrates a keyboard utilizing masking to block light from escaping between the keys. 
       
    
    
     DETAILED DESCRIPTION 
     Overview 
       [0023]    This detailed description is made with reference to the accompanying drawings, which form a part hereof, and which show, by way of illustration, specific exemplary embodiments. These embodiments are described in sufficient detail to enable those skilled in the art to practice what is taught below, and it is to be understood that other embodiments may be utilized and that logical, mechanical, electrical, and other changes may be made without departing from the spirit or scope of the subject matter. The following detailed description is, therefore, not to be taken in a limiting sense, and its scope is defined only by the appended claims. 
         [0024]    The concepts of the present disclosure are applicable to a variety of keyboards, keypads, and similar devices. Herein, the disclosure is presented primarily with respect to a computer keyboard. This is an exemplary application and not a limiting application. Cellular telephones, personal digital assistants (PDAs); remote controls, mobile audio devices; and a wide range of other devices which use keys for input are contemplated as being in the scope of the disclosure. Herein, the term keyboard is intended to also encompass keypads and similar devices. 
         [0025]      FIG. 1  presents a simplified diagram of an exemplary computer keyboard  100 . As is typical it comprises a variety of types of keys including alphanumeric, function, and navigation keys among others. Region  102  is a subset of the keys which is often referred to as the “number keys”. These keys provide a simple example of keys which have dual symbol sets. When the shift key  108  is not activated, these keys are used to type the digits 1-9 and 0. With the shift key  108  pressed, they are used to input a set of special characters. In certain situations, it may be desirable to provide a visual indication, herein “highlighting,” of which function they are performing. 
         [0026]    Region  104  of the keyboard illustrates a slightly more complex example of keys which have been “overloaded” with more than one function. In a typical approach to keyboards for laptop computers, there is not a separate keypad for numeric input as is available in a conventional full sized keyboard. Instead, this region of the main keyboard can be used as a numeric keypad by activating a “number lock” (NumLock) key  110  which alters the functionality of a subset of the keys. As above, it may be desirable to provide a visual indication of which function these keys are performing. 
         [0027]    Clearly, these concepts can be extended to other devices with overloaded input keys. A cellular telephone may provide a conventional telephone numeric keypad for use in dialing, but use the same keys for alphanumeric input for text messaging or as function keys to control a built-in audio player. A car stereo may use a single set of buttons to select radio stations while in radio mode and to select tracks and/or CDs when in compact disc mode. These and other applications are merely other applications of the key overloading concepts discussed herein with respect to the computer keyboard. 
         [0028]    Referring to  FIGS. 2A and 2B , the overloaded keys which are usable as a numeric keypad, and one key in particular, can be seen in more detail. With NumLock key  110  off, these keys behave as a part of the standard keyboard. With NumLock key  110  on, they act as a numeric keypad. Key  200  is representative of the overloaded functionality. With NumLock key  110  off, and the shift key  108  not depressed, key  200  provides for typing the zero character “0” as indicated by symbol  204 . With NumLock key  110  off, and the shift key  108  depressed, key  200  will type a closing parenthesis ”)” as indicated by symbol  202 . With NumLock key  110  on, key  200  becomes the upper right key of a numeric keypad, providing the division function “/” as indicated by symbol  206 . Two different cross-section views of key  200  along line  10 - 10  are shown in  FIGS. 5 and 6 . 
         [0029]    Referring to  FIGS. 3A and 3B  an exemplary highlighting scheme can be seen. In this scheme, symbols  202  and  204  are considered to be a part of a first symbol set, those used on the conventional keyboard, and are highlighted (depicted in bold to represent highlighting) in combination along with the equivalent symbols on related keys. Symbol  206  is considered to be a part of a second symbol set, those used for the numeric keypad, which can be highlighted independently of the first set (depicted in gray scale to represent non-highlighting). As illustrated, highlighting the symbols of the conventional keyboard makes them more easily distinguished from the overloaded symbols for the keypad. 
         [0030]      FIGS. 4A and 4B  illustrate the same highlighting scheme as  FIGS. 3A and 3B  with the highlighting reversed. With the symbols of the numeric keypad, such as symbol  206 , highlighted (shown highlighted in bold), they become easily distinguished from the symbols of the conventional keyboard (shown non-highlighted as gray scale). 
       Keyboard Structure and Materials 
       [0031]      FIG. 5  illustrates an exemplary technique for constructing an individual key according to the concepts of the present disclosure. The body  500  of the key  200  is constructed of a substantially opaque material such as a dark plastic. The symbols,  202 - 206  in  FIG. 2B , are formed by portions  502 - 508  of the key  200  which are capable of transmitting at least some light. These portions may be either transparent or translucent as desired. In the illustrated cross section, portion  502  corresponds to symbol  202  and portions  504 ,  506 , and  508  to symbol  206 . 
         [0032]    In an exemplary embodiment, symbols  202  and  204  and all related symbols in the first symbol set will be formed of a light transmitting material adapted to pass visible light. These symbols will then be highlighted when lit from below by a visible light source  510 . Symbol  206 , and all related symbols in the second symbol set, will be formed of a light transmitting material which is adapted to fluoresce when excited by a non-visible light source such as ultra-violet (UV) light source  512 . Thus, when the UV light source is active, the light will be transmitted by symbols  202  and  204  but will not cause the symbol to be highlighted because the light is not visible to the user. However, the UV light will cause symbol  206  to fluoresce, emitting visible light which will highlight the symbol to the user. 
         [0033]    Where the material used for symbol  206  is uncolored, the visible light source  510  will also highlight symbol  206 . An alternative embodiment is to use a colored material which is complementary to the visible light source  510 . One exemplary embodiment is to use a blue light source and a translucent yellow material for symbol  206 . The yellow material will filter most or all of the blue light with the result that the symbol will not be highlighted by the visible light source  510 . Another exemplary approach is to overlay or coat the fluorescent symbol with a colored filter layer. 
         [0034]    One exemplary embodiment of the keys, as discussed above, is to form the symbols which are intended to fluoresce of material which itself fluoresces. An exemplary technique is to embed fluorescent powder in a light transmitting material and form the symbols from that material. 
         [0035]    Another exemplary embodiment of the keys is illustrated in  FIG. 6 . In this embodiment none of the material used to form the symbols is fluorescent. Instead a fluorescent material  602  is laid over the symbol which is intended to be highlighted. When the UV light source  512  causes the material to fluoresce, the emitted visible light will pass through the adjacent light transmitting portions  504 ,  506 , and  508  highlighting the symbol to the user. The fluorescent material could overlay either the inner surface, as illustrated, or the outer surface of the key. 
         [0036]    Filtering of visible light, as discussed above, can be achieved in two different manners when the overlay embodiment of  FIG. 6  is used. One exemplary embodiment is to form the symbol  206  of a colored, but non-fluorescent material so that the symbol itself filters the complementary colored light. Another exemplary approach is to use a colored, fluorescing material for the overlay  602 . In this embodiment the overlay provides both the filtering and the fluorescence. This allows all symbols in the key to be formed from the same light transmitting material. 
         [0037]    Referring to  FIG. 9  an exemplary embodiment of the keyboard can be seen which provides masking  900  which blocks light from escaping between the keys. This increases the contrast between the illuminated symbols and the background formed by the keys. This masking may be provided by separate masking material, which could be made of plastic, cardboard, or metal or some other suitable material, which blocks the gap between the keys, as shown, or by configuring the keys so that they block the gap, such as by overlapping the edges of the keys so that one passes beneath the other. 
         [0038]    In an exemplary embodiment, the keys are constructed to limit the amount of ultraviolet light which escapes past the keys. In addition to the above masking, the keys will be constructed to block or filter ultraviolet light. The opaque portions of the keys will be constructed of a material which blocks ultraviolet rays. In an embodiment of the type illustrated by  FIG. 6  the translucent portions of the keys will utilize material which filters ultraviolet while passing visible light. An embodiment of the type illustrated by  FIG. 5  will utilize material which filters enough ultraviolet to ensure that an unacceptable amount of light cannot pass through while allowing enough to penetrate the material so that the fluorescent material will be excited. 
       Light Source 
       [0039]    The use of fluorescent symbols in combination with a UV light source eliminates the need for separate light sources for each symbol. Instead the light sources can be shared across a plurality of keys. The layout of light sources relative to the keys can be tailored to the functionality of the keys and can be balanced against cost and design factors. In all cases, the light sources will be positioned behind, or beneath, the keys so that the keys are backlit. 
         [0040]    An exemplary embodiment for a smaller keypad, such as for a cellular phone or PDA, a single light bulb, or LED, for each frequency may be sufficient. Thus a single pair of light sources is sufficient for the entire keypad. 
         [0041]    An exemplary embodiment for a larger set of keys, such as a full sized conventional keyboard for a computer, may require multiple light sources, or a broad area light source, in order to provide even illumination across all of the keys. An exemplary broad area light source suitable for use in keyboards and keypads is an LED array but the present disclosure is not specific to that mechanism. Referring to  FIG. 7  an exemplary LED array, adapted for use with a keyboard layout such as that shown in  FIG. 1 , can be seen. Group  700  emits visible light and group  702  emits UV light. 
         [0042]    Another exemplary embodiment for a larger keyboard or keypad is to use 2 or more light sources, of one or both frequencies, to allow greater control over highlighting keys which are used for different functions. Referring to  FIG. 1 , the region  104  of keys which comprise the numeric keypad, as discussed above, may use a separate set of light sources than the rest of the keyboard. This allows the numeric keypad symbol set to be highlighted without altering the appearance of the remainder of the keys. Referring to  FIG. 8 , group  804  emits visible light for the numeric keypad, group  806  emits UV light for the numeric keypad, group  800  emits visible light for the remainder of the keyboard and group  802  emits UV light for the rest of the keyboard. Alternatively, a single visible light source of one frequency (i.e. visible light) could be used for the entire keyboard, while separate light sources of the other frequency (i.e. UV) could be used for the numeric keypad and the remainder of the keyboard. 
         [0043]    In a similar manner, the top row of keys, the “function” keys  112 , may be provided with separate light sources. Because these keys may have a first set of functionality in normal use, and a second set of functionality when the function key (“fn”)  106  is depressed it may be desirable to highlight the alternate symbology when the “fn” key is depressed. This configuration could be used as an alternative to one such as that shown in  FIG. 8 , or in combination with that configuration providing a total of three separately controllable highlighting options. Clearly, additional configurations and combinations thereof are possible. 
         [0044]    With two separately controlled light sources available, a total of four modes of operation are available: unlighted—user is dependent upon ambient lighting to see the symbols on the keys; visible light—those symbols which are adapted to pass visible light will be highlighted; UV light—those symbols which fluoresce will be highlighted; and both visible and UV illumination—both symbol sets will be highlighted (such as for low ambient light situations). 
         [0045]    Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims. It will be understood by those skilled in the art that many changes in construction and widely differing embodiments and applications will suggest themselves without departing from the scope of the disclosed subject matter.