Abstract:
An electroluminescent switch membrane for use in a keyboard associated with an information handling system is disclosed. The electroluminescent switch membrane may include a first and a second sheet of film configured as opposing electrodes of a capacitor. The switch membrane may include an electroluminescent material disposed between the two sheets of film. The switch membrane may include a plurality of conductive traces printed on the first sheet of film. The switch membrane may include a plurality of switches disposed on the first sheet of film, each switch configured to complete a respective circuit with the conductive traces when the switch is depressed. In addition, the electroluminescent switch membrane may be configured to illuminate the keyboard when an electric current is passed through the electroluminescent material.

Description:
TECHNICAL FIELD 
     The present disclosure relates in general to keyboards for use with information handling systems, and more particularly to keyboards with integrated electroluminescent illumination. 
     BACKGROUND 
     As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems. 
       FIG. 1  depicts selected elements of an example prior art information handling system  1 . Information handling system  1  includes a host  10 , which may include processing resources (e.g., one or more central processing units (CPUs) and storage resources that are accessible to the processing resources) in a housing  12 . Storage resources may include volatile storage or memory and/or persistent storage, e.g., disk storage, flash memory or other type of erasable read only memory (ROM), and the like. Information handling system  1  may also include various other peripheral or I/O devices known in the field of data processing system design, such as mouse  14  and display  20  shown in  FIG. 1 . 
     Host  10  may include a keyboard  30 . As shown in  FIG. 1 , keyboard  30  may include a set of keycaps (and/or buttons)  32  operable to provide input to host  10 . One example of keyboard  30  includes a set of keycaps  32  arranged in the so-called “QWERTY” character set, which has been used for typewriters. In a standard keyboard  30 , keycaps  32  display one or more imprinted characters, for example, characters corresponding to alphanumeric characters, mathematical functions, and/or specialized function keys. 
     Information handling system  1  may include a mobile information handling device, e.g., laptop  10  shown in  FIG. 2  or any other type of mobile computing device (e.g., a tablet computer, a notebook computer, a PDA, a cellphone, etc.). Case  12  may include any chassis, cabinet, tower, box, and/or enclosure appropriate for housing information handling system  1 . Display  20  may include any information display for visual presentation of images, texts, and/or other output from information handling system  1 . Keyboard  30  may include any arrangement of buttons and/or keys designed for the input of text, characters, and/or operational controls for information handling system  1 . Keyboard  30  may include individual keycaps  32 . 
     Laptop  10  may also include processing resources, e.g., one or more central processing units (CPUs) and storage resources that are accessible to the processing resources. Storage resources may include volatile storage or memory and/or persistent storage, e.g., disk storage, flash memory or other type of erasable read only memory (ROM), and the like. 
       FIGS. 3 and 4   a - 4   b  show some of the construction details of a typical keyboard  30 , including keycaps  32 , a scissor mechanism  34 , a cosmetic mask  36 , a switch membrane  40 , electronic circuit traces  42 , a dome switch  44 , a ribbon connector  46 , and a base plate  50 . 
     Base plate  50  is often made of metal and provides structure for keyboard  30 . In addition, base plate  50  provides mounting points for other components of keyboard  30 . Switch membrane  40  is disposed between base plate  50  and keycaps  32 . Switch membrane  40  is often made of plastic film. Electronic circuit traces  42  are printed on the surface of switch membrane  40 . Electronic circuit traces  42  are typically printed with silver ink onto switch membrane  40 . 
     Dome switch  44  is a commonly used switch sometimes called a “direct-switch” mechanism. Dome switch  44  is positioned beneath keycap  32  and collapses between base plate  50  and keycap  32  when keycap  32  is depressed by a user. The inner surface of dome switch  44  is coated with an electrically conductive material, so when dome switch  44  collapses, the conductive material completes a circuit between electronic circuit traces  42  printed on switch membrane  40 . 
     In keyboard  30  incorporating scissor mechanism  34 , keycaps  32  are typically attached to keyboard  30  using two plastic arms that interlock like scissors. Scissor mechanism  34  snap connects to both keyboard  30  and keycap  32 . Cosmetic mask  36  typically conceals portions of keyboard  30  from a user&#39;s line-of-sight. 
       FIG. 4   b  illustrates an example prior art switch membrane  40  with electronic circuit traces  42 , dome switches  44 , and ribbon connector  46  for use in keyboard  30 . Switch membrane  40  includes a plurality of switches (e.g., dome switches  44 ). Ribbon connector  46  is an electrical connection between electronic circuit traces  42  and host  10  or information handling system  1 . Switch membrane  40  is perforated as shown in  FIG. 4   b  so that scissor mechanisms  34  can be connected to base plate  50  through the perforations. 
       FIG. 5  illustrates an example electroluminescent panel  60  (EL Panel) that is used to provide backlighting for some keyboards. EL Panel  60  includes holes  62  and a lead  64 . In general, an electroluminescent panel typically includes two sheets of plastic film bonded together to form a capacitor. The space between the two sheets is typically filled with an electroluminescent material (e.g., powder phosphor, zinc sulfide, etc.). Electroluminescent materials emit light in response to an electric current passing through the material. EL Panel  60  emits light in response to application of current across the capacitor formed by the sheets of plastic film. EL Panel  60  is perforated with holes  62  so that scissor mechanisms  34  may connect keycaps  32  to base plate  50  and/or so that dome switches  44  may protrude through EL Panel  60 . Lead  64  provides an electrical connection between EL Panel  60  and other portions of keyboard  30  to provide electric current to the electroluminescent material. 
     Other keyboards provide backlighting through the use of light emitting diodes (LED) that illuminate a large sheet by edge lighting. Such a solution, however, typically consumes a great deal of power and adds bulk and weight to a keyboard. LED solutions may not be satisfactory for use in a mobile information handling system where size and weight are important design parameters. 
     SUMMARY 
     In accordance with one embodiment of the present disclosure, an electroluminescent switch membrane for use in a keyboard associated with an information handling system is disclosed. The electroluminescent switch membrane may include a first and a second sheet of film configured as opposing electrodes of a capacitor. The switch membrane may include an electroluminescent material disposed between the two sheets of film. The switch membrane may include a plurality of conductive traces printed on the first sheet of film. The switch membrane may include a plurality of switches disposed on the first sheet of film, each switch configured to complete a respective circuit with the conductive traces when the switch is depressed. In addition, the electroluminescent switch membrane may be configured to illuminate the keyboard when an electric current is passed through the electroluminescent material. 
     In accordance with a further embodiment of the present disclosure, a keyboard configured for use with an information handling system may include a first and a second sheet of film configured as opposing electrodes of a capacitor, an electroluminescent material disposed between the two sheets of film, a plurality of conductive traces printed on the first sheet of film, a plurality of keycaps disposed above the first sheet of film, and a plurality of switches disposed between the keycaps and the first sheet of film, each switch configured to complete a respective circuit with the conductive traces when the respective keycap is depressed. The electroluminescent material may be configured to illuminate the keyboard when an electric current is passed through the electroluminescent material. 
     In accordance with another embodiment of the present disclosure, an information handling system may include a processor, a memory communicatively coupled to the processor, and a keyboard configured to communicate electrical signals to the processor in response to user input. The keyboard may include a first and a second sheet of film configured as opposing electrodes of a capacitor, an electroluminescent material disposed between the two sheets of film, a plurality of conductive traces printed on the first sheet of film, a plurality of keycaps disposed above the first sheet of film, and a plurality of switches disposed between the keycaps and the first sheet of film, each switch configured to complete a respective circuit with the conductive traces when the respective keycap is depressed. The electroluminescent material may be configured to illuminate the keyboard when an electric current is passed through the electroluminescent material. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein: 
         FIG. 1  illustrates an example prior art information handling system; 
         FIG. 2  illustrates an example prior art information handling system; 
         FIG. 3  illustrates an example prior art keyboard for use with an information handling system; 
         FIG. 4   a  illustrates selected components of an example prior art keyboard for use with an information handling system; 
         FIG. 4   b  illustrates an example switch membrane for use in a keyboard; 
         FIG. 5  illustrates an example electroluminescent panel for use in a keyboard; 
         FIGS. 6   a - 6   c  illustrate three example constructions for illuminated keyboards; and 
         FIGS. 7   a - 7   c  illustrate an example construction for an illuminated keyboard in accordance with the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Preferred embodiments and their advantages are best understood by reference to  FIGS. 1-7   c , wherein like numbers are used to indicate like and corresponding parts. 
     For the purposes of this disclosure, an information handling system may include any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, entertainment, or other purposes. For example, an information handling system may be a personal computer, a PDA, a consumer electronic device, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The information handling system may include memory, one or more processing resources such as a central processing unit (CPU) or hardware or software control logic. Additional components or the information handling system may include one or more storage devices, one or more communications ports for communicating with external devices as well as various input and output (I/O) devices, such as a keyboard, a mouse, and a video display. The information handling system may also include one or more buses operable to transmit communication between the various hardware components. 
       FIGS. 6   a - 6   c  illustrate three example constructions for illuminated keyboards. As shown in  FIGS. 6   a - 6   c , keycap  32  may be connected to base plate  50  by scissor mechanism  34 . Any layer interposed between keycap  32  and base plate  50  must be perforated to accommodate scissor mechanism  34 . For example, in  FIG. 6   a , switch membrane  40  must be perforated. In  FIGS. 6   b  and  6   c , both switch membrane  40  and EL Panel  60  must be perforated to accommodate scissor mechanism  34 . When EL Panel  60  is perforated, it reduces the illuminated surface area of EL Panel  60  and may reduce the light emitted from EL Panel  60 . 
     In examples such as that shown in  FIG. 6   a , EL Panel  60  is positioned below base plate  50 . This arrangement allows EL Panel  60  to be installed without perforation. However, base plate  50  must either be transparent to light or perforated to allow light to pass through. Most base plates  50  used in keyboards  30  are formed of solid metal. It is estimated that base plate  50 , even if perforated, blocks more than one-half of the illuminated surface of EL Panel  60 . 
       FIGS. 7   a - 7   c  illustrate an example construction for an illuminated keyboard in accordance with the present disclosure. As shown in  FIG. 7   a , the present disclosure allows an illuminated keyboard including fewer components that the constructions discussed in relation to  FIGS. 6   a - 6   c . The illuminated keyboard may include keycap  32 , scissor mechanism  34 , base plate  50 , and an electroluminescent switch membrane  70 . 
     Keycap  32  and scissor mechanism  34  may be any device, feature, or component of a keyboard configured to cooperate to allow a keyboard to recognize user input (e.g., complete an electronic circuit when keycap  32  is depressed). Keycap  32  may be made of plastic or any other suitable material. In some embodiments, keycap  32  may be molded in a clear or translucent material. Keycap  32  may be painted with an opaque material then characters etched within the opaque material. Illumination on keycap  32  from below will pass through keycap  32  and may be seen by a user. 
     Scissor mechanism  34  may be any structure or device configured to connect keycap  32  to base plate  50 , to support keycap  32  in a raised position, to allow a user to depress keycap  32 , and to return keycap  32  to its raised position after the user has removed his or her finger. Scissor mechanism may include plastic, metal, or any other appropriate material. 
     Base plate  50  may include any material configured to connect with scissor mechanism  34  and allow mounting of keycap  32  on base plate  50 . For example, base plate  50  may include a flat sheet of metal (e.g., aluminum and/or steel). As another example, base plate  50  may include a sheet of rigid plastic. In mobile information handling devices, the thickness and/or material selection of base plate  50  may be chosen to reduce the weight of the mobile information handling device. As shown in  FIG. 7   a , base plate  50  is positioned below electroluminescent switch membrane  70 , so base plate  50  need not be perforated to allow light to pass therethrough. 
     As shown in  FIGS. 7   b  and  7   c , electroluminescent switch membrane  70  may include electronic circuit traces  72 , a connector  74 , a lead  76 , holes  78 , dome switches  80 , electroluminescent illuminated areas  82 , and a cosmetic mask  84 . Electroluminescent switch membrane  70  may include any device or component configured to operate in conjunction with keycap  32  and scissor mechanism  34  to provide user input to a keyboard and configured to provide electroluminescent backlighting to keycaps  32  and/or the keyboard. 
     For example, electroluminescent switch membrane  70  may include one or more plastic sheets (e.g., mylar) including electronic circuit traces  72 . Electronic circuit traces  72  may be any component or feature of electroluminescent switch membrane  70  configured to conduct electricity between dome switches  80  and other components of a keyboard. When dome switches  80  are activated, one or more circuits may be completed on electronic circuit traces  72 . In some example embodiments, electronic circuit traces  72  may be printed onto electroluminescent switch membrane in silver ink. 
     Connector  74  may include any cable or wire configured to communicate electric signals from electroluminescent switch membrane  70  to other portions of a keyboard or an information handling system. For example, connector  74  may include an insulation displacement connector (IDC) or a solder-bucket connection providing electrical contacts for a ribbon cable. Connector  74  may be chosen for compatibility with software, firmware, or hardware related to the operation of a keyboard. Connector  74  may be configured to communicate the electrical signals generated when keycap  32  is depressed. 
     Lead  76  may include any cable or wire configured to communicate electrical signals from electroluminescent switch membrane  70  to other portions of a keyboard or an information handling system. For example, lead  76  may include a length of wire, a soldering pad, pins, and/or any other component operable to provide power to electroluminescent switch membrane  70  for use in illumination. In other embodiments, connector  74  and lead  76  may be integrated to provide a single connection between electroluminescent switch membrane and other components of a keyboard or an information handling system. 
     Holes  78  may include any portion of electroluminescent switch membrane  70  configured to allow physical passage of components of a keyboard. For example, holes  78  may be configured to allow scissor mechanism  34  to pass through electroluminescent switch membrane  70  and connect to base plate  50 . 
     Dome switches  80  may include any component or feature of electroluminescent switch membrane  70  configured to collapse between base plate  50  and keycap  32  when keycap  32  is depressed by a user. Each dome switch  80  may be positioned beneath a keycap  32 . The inner surface of each dome switch  38  may be coated with an electrically conductive material, so when the dome switch  38  collapses, the conductive material completes a circuit between electronic circuit traces  72  of electroluminescent switch membrane  70 . In other embodiments, electroluminescent switch membrane  70  may include scissor switches, capacitive switches, mechanical switches, buckling spring switches, hall-effect switches, and/or laser switches to complete an electrical circuit in conjunction with electronic circuit traces  72 . 
     Electroluminescent illuminated areas  82  may include portions of electroluminescent switch membrane  70  configured to emit light in response to an electric current passing through electroluminescent material within electroluminescent switch membrane  70 . In some embodiments, electroluminescent switch membrane may include two sheets of plastic film bonded together to form a capacitor. The space between the two sheets may be filled with an electroluminescent material (e.g., powder phosphor, zinc sulfide, etc.). 
     Cosmetic mask  84  may include any portion of electroluminescent switch membrane  70  configured to block light from passing through. For example, cosmetic mask  84  may include portions of electroluminescent switch membrane  70  not including electroluminescent material so that light is not emitted from those portions. As another example, cosmetic mask  84  may be an opaque material printed on or otherwise disposed on or in electroluminescent switch membrane  70  so that illumination will not pass through cosmetic mask  84 . 
     The example construction shown in  FIGS. 7   a - 7   c  may offer improvements over the constructions shown in  FIGS. 6   a - 6   c . For example, electroluminescent switch membrane  70  reduces the number of layers of material included in the assembly, which may reduce the cost of manufacturing, the height of the stack, the weight of the construction, and/or provide additional benefits related to the elimination of extra material. As another example, electroluminescent switch membrane  70  may have fewer holes than EL Panel  60 , which may allow for more illumination surface area. 
     Although the present disclosure has been described in detail, it should be understood that various changes, substitutions, and alterations can be made hereto without departing from the spirit and the scope of the disclosure as defined by the appended claims.