Abstract:
A portable computer comprises a housing and an EL panel within the housing, positioned to emit light outwardly from the housing. The EL panel includes a plurality of EL lamps that, together, form a logo. The EL lamps can be addressed separately, enabling one to produce the appearance of motion for decorative effect or to indicate a condition of the portable computer or both.

Description:
FIELD OF THE INVENTION 
       [0001]    This invention relates to thick film electroluminescent (EL) lamps and, in particular, to an EL panel in the form of a logo in a portion of a case for a portable electronic device, such as a portable computer. 
       GLOSSARY 
       [0002]    As used herein, an EL “panel” is a single substrate including one or more luminous areas, wherein each luminous area is an EL “lamp.” 
         [0003]    A “thick film” EL lamp refers to one type of EL lamp and “thin film” EL lamp refers to a different type of EL lamp. The terms only broadly relate to actual thickness and actually identify distinct disciplines. A thin, thick film EL lamp is not a contradiction in terms and such a lamp is considerably thicker than a thin film EL lamp. Thick film EL is generally based upon inks deposited on a substrate, wherein the inks contain solvent, binder and filler. The filler determines the nature of the film; phosphor, dielectric, or conductor. 
         [0004]    A “phosphor layer” is not restricted to a single phosphor and does not exclude cascading phosphors or dyes for color enhancement. 
         [0005]    A “graphic” can be text, a symbol, an arbitrary shape, or some combination thereof. A graphic can be translucent, shaded, colored, a silhouette or outline, or some combination thereof. 
         [0006]    A “logo” is a graphic that is a symbol of or a trademark for a person (legal or natural), a group of people, a service, a place, or a thing. “Logo” includes a defined field, if any, surrounding or highlighting the symbol or trademark. 
         [0007]    “Opaque” does not mean that no light is transmitted, only that the amount of light transmitted is substantially reduced, e.g. to ten percent of incident light. 
         [0008]    “Obscure” might be another term. 
         [0009]    “Transparent” does not mean that all light is transmitted, only that enough light is transmitted to recognize a graphic. 
         [0010]    A “portable computer” is a system containing a keyboard, display, and microprocessor chip set, inside a single enclosure or housing. The enclosure is typically two pieces or shells hinged along one edge and opening to reveal the display in one half and the keyboard in the other half. “Enclosure” does not necessarily mean fully enclosed. “Portable computer” is generic to “notebook”, “netbook”, “laptop” or other terms for lightweight, compact systems. 
         [0011]    A “flat panel display” is any display that is relatively thin compared with the dimensions of the display area. 
         [0012]    In general, all words are used without resort to extreme interpretation or to semantics at the expense of reality. The words are used within their ordinary meaning, either in everyday speech or as jargon in a particular technology, as appropriate. 
       BACKGROUND OF THE INVENTION 
       [0013]    An EL lamp is essentially a capacitor having a dielectric layer between two conductive electrodes, one of which is transparent. The dielectric layer includes phosphor or there is a separate layer of phosphor adjacent the dielectric layer. The phosphor emits light in the presence of a strong electric field, using very little current. The light is substantially uniform across the area of the lamp and the lamp is relatively thin, making it desirable for back lighting displays, for which EL lamps have long been used. 
         [0014]    Animated displays using EL lamps are old in the art; e.g. see U.S. Pat. No. 2,773,216 (Edmonds) and U.S. Pat. No. 6,205,690 (Heropoulos et al.). 
         [0015]    Most portable computers have opaque logos on the upper half of their enclosure. Back lit logos for portable computers are known in the art; e.g. see U.S. Pat. No. 6,977,808 (Lam et al.). Back lit or not, the logo is not particularly eye-catching. 
         [0016]    A difficulty with the construction described in the &#39;808 patent, aside from cost and complexity, is that the logo is lit only to the extent that the display is active. If the display is dimmed or turned off, the logo is dimmed or turned off; e.g. when attaching an external display or when the computer is in a low power (“sleep”) mode or turned off. 
         [0017]    Another difficulty is that the logo is monochromatic, derived from the light from the display itself, averaged over all the pixels of various colors. 
         [0018]    It is known in the art to use a logo on a cellular telephone to indicate connection to a wireless network; see U.S. Patent Application Publication No. 2004/0204151 (Muthuswamy et al.). U d as an indicator, the logo is dark when there is no connection, making the logo difficult to see at least some of the time, which is undesirable. 
         [0019]    It is known in the art to provide a secondary display in the cover of a closed device; e.g. U.S. Patent Application Publications 2008/0074899 and 2008/0076253. 
         [0020]    It is known in the art how to mold an EL lamp as integral part of a component; see U.S. Patent Application Publication 2005/0067952 (Fechter et al.), which is incorporated herein by reference. Molding EL lamps into three dimensional shapes is also known in the art; see the patents discussed in the Background portion of the Publication. 
         [0021]    In view of the foregoing, it is therefore an object of the invention to provide a back lit logo for a portable computer, wherein the logo is illuminated independently of the display in the computer. 
         [0022]    Another object of the invention is to provide a luminous, animated logo for portable computers. 
         [0023]    A further object of the invention is to provide a luminous, animated logo for portable computers that conveys information about the state of the portable computer. 
         [0024]    Another object of the invention is to provide an animated EL panel in the shape of a logo. 
         [0025]    A further object of the invention is to back light a logo with an animated EL panel. 
       SUMMARY OF THE INVENTION 
       [0026]    The foregoing objects are achieved by the invention in which a portable computer comprises a housing and an EL panel within the housing itself, positioned to emit light outwardly from the housing. The EL panel includes a plurality of EL lamps that, together, form a logo. The EL lamps can be addressed separately, enabling one to produce the appearance of motion for decorative effect or to indicate a condition of the portable computer or both. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    A more complete understanding of the invention can be obtained by considering the following detailed description in conjunction with the accompanying drawings, in which: 
           [0028]      FIG. 1  is a perspective view of a portable computer having a logo in the upper shell of the enclosure; 
           [0029]      FIG. 2  is a plan view of the upper shell of a portable computer constructed in accordance with a preferred embodiment of the invention; 
           [0030]      FIG. 3  is a cross-section of a shell for a portable computer illustrating a first embodiment of the invention; 
           [0031]      FIG. 4  is a cross-section of a shell for a portable computer illustrating a first embodiment of the invention; 
           [0032]      FIG. 5  is a cross-section of a shell for a portable computer illustrating a second embodiment of the invention; and 
           [0033]      FIG. 6  is a cross-section of a shell for a portable computer illustrating a third embodiment of the invention; and 
           [0034]      FIG. 7  is a perspective view of a portable computer having a logo in the lower shell of the enclosure. 
       
    
    
       [0035]    The figures are not drawn to scale but merely illustrate various aspects of the invention. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0036]    In  FIG. 1 , personal computer  10  includes base  12  and display unit  14 . Base  12  includes keyboard  13  and suitable electronics such as a microprocessor, input/output ports, wireless communication, battery, charger, and power supply. Display unit  14  contains flat panel display  15  in the volume defined by shell  17 . Flat panel display  15  emits light toward a viewer, across keyboard  13 . In accordance with one aspect of the invention, shell  17  defines logo site  19  for an EL panel that emits light in a direction opposite to that of display  15 . 
         [0037]    In  FIG. 2 , shell  17  includes EL panel  21  approximately centrally located within the shell itself; i.e., EL panel  21  is part of the structure of shell  17 , as opposed to being contained within the volume defined by the shell. EL Panel  21  need not be centrally located. EL panel  21  includes a plurality of lamps, such as lamps  23 ,  24 , and  25 . Lamps  23  and  24  are arcs of a circle surrounding a logo, represented by the letters “A,” “C,” “M,” and “E.” Each of the letters is preferably a separate lamp. Alternatively, lamp  25  could include all four letters. Area  26  may or may not include a lamp. If area  26  is a lamp, one has the opportunity to reverse the appearance of the logo, when the logo can be reversed photographically and remain a proper representation of a trademark. By “reverse” is meant interchanging light areas and dark areas. 
         [0038]    In accordance with another aspect of the invention, the EL panel provides an indication of a condition within portable computer  10 ; e.g. temperature or level of battery charge. The indication can be by brightness, color, motion, progression, or some combination of these effects. The lamps forming the circle can be lit sequentially to indicate battery capacity, for example. The display can be static, as a speedometer or bar graph, or moving, where lamps are sequentially lit and remain lit until a maximum is reached and then the sequence begins again. The entire circle can represent one condition or a portion of the circle can be used; e.g. two arcs of 180° each, one arc for each condition. 
         [0039]    In accordance with another aspect of the invention, decorative effects can be provided by powering the lamps in various combinations and sequences. Indication and decoration can be combined. 
         [0040]      FIG. 3  illustrates a first embodiment of the invention in which shell  30  includes a recess in the outer surface thereof in which EL panel  31  rests. EL panel  31  is protected by cover  33  and emits light in the direction indicated by arrow  34 . An aperture (not shown) allows conductive leads to be passed through shell  30  for connection to a source of power. 
         [0041]      FIG. 4  illustrates a second embodiment of the invention in which shell  40  includes a recess in the inner surface thereof in which EL panel  41  rests. EL panel  41  is protected by cover  43  and emits light in the direction indicated by arrow  44  through a transparent portion of shell  40 . 
         [0042]      FIG. 5  illustrates a preferred embodiment of the invention in which EL panel  51  is molded into shell  50  in the manner described in U.S. Patent Application Publication 2005/0067952. EL panel  51  is placed in a mold and plastic is injected into the mold to form shell  50 . The panel and shell are then a single unit. EL panel  51  emits light in the direction indicated by arrow  54 . This embodiment enables one to produce economically a large number of shells bearing the same logo. 
         [0043]      FIG. 6  illustrates an alternative embodiment of the invention in which the EL panel is sandwiched between two plates, at least one of which is transparent. EL panel  61  is located in a hole in shell  60  and is held in place by plates  63  and  64 . For the sake of example, plate  63  is transparent and light is emitted in the direction shown by arrow  66 . The plates are held in place by friction or adhesive. To increase contact area, the plates preferably include a shoulder extending over a portion of shell  60  around at least some of the perimeter of the hole. Either plate can serve as a substrate during the manufacture of EL panel  61  or EL panel  61  is laminated to one plate to facilitate handling during manufacture. 
         [0044]      FIG. 7  illustrates an alternative embodiment of the invention. Logo  71  is on the outside of a shell containing keypad  72 . Display  74  is located in the other half of electronic device  70 . 
         [0045]    The invention thus provides a back lit logo for a portable computer, wherein the logo is illuminated independently of the display in the computer. The logo can be animated and convey information about the state of the portable computer. Alternatively, a logo is back lit by an animated EL panel. 
         [0046]    Having thus described the invention, it will be apparent to those of skill in the art that various modifications can be made within the scope of the invention. For example, although described in the context of a portable computer, the invention can be used with other electronic devices, e.g. desktop computers and cellular telephones. In any of the embodiments of the invention, the EL panel can be used to back light an opaque symbol or trademark.