Abstract:
The present invention is an electroluminescent device which proves a means for illuminating push-button devices such as television remote controllers, keypads for security systems, computer keyboards, beepers, night lights, telephones, portable emergency lighting, calculators, and like devices. The invention comprises a power supply which includes an electrical voltage inverter and a power source, and which is connected to a thin and flexible electroluminescent planar sheet containing embedded circuitry and powered by alternating current. The individual components are connected together by electrical leads. The thin electroluminescent lamp portion of the invention provides an even area of template illumination when it is placed over push buttons of an underlying device, and that device can then be used under low-level illumination, or even in complete darkness. Additionally, the present invention allows augmentation of existing illumination. The invention can be added during the manufacturing process, or it can be retrofitted by the end-user to upgrade devices already in use. The planar sheet can be manufactured to glow in one or more of several colors, to suit the needs of the manufacturer or end-user.

Description:
This is a Continuation of U.S. patent application Ser. No. 08/634,026 filed on Apr. 17, 1996, now U.S. Pat. No. 5,899,553. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to the field of hand-operated illuminating devices, and, more particularly, to a circuit for illuminating a template surrounding push buttons of hand-held devices. 
     BACKGROUND OF THE INVENTION 
     Many devices operated by push buttons are used in low light, such as that available to home users during evening hours. Many such commercially available devices are not easily readable under subdued lighting or illumination, like that light emitted by a television screen. To read such devices under low light, one must usually turn on a light or take the device to adequate lighting to read the device. 
     Illumination added directly to such push-button devices typically involves an incandescent lamp. Incandescent illumination is often overdone or under-done. Further, unevenness in the area of illumination of the device may be harsh to the eye and distracting when the use of the device is merely ancillary to other activities. In situations in which safety and security are primary, turning on an incandescent lamp may expose the user to danger, and may result in a momentary loss of night vision. Exposing the controls in harsh, uneven light makes the use of the remote control device more difficult for the elderly or the visually impaired. 
     Thus, there remains a need for an apparatus and a method for illuminating such push-button devices that is not under or over done, is not harsh or uneven in illumination for the user or others in the vicinity, and is not distracting to the main activity for which the push-button controller is being used. Such a method of illumination should not unduly expose the user to harm by drawing attention to the use of the device, should not cause a momentary loss of night vision, or make the device more difficult to use. It should allow the user to turn on the light only momentarily. Also, the process of illuminating the device should not cause a change in the normal pattern of using the device, such as by requiring different fingering to turn on other functions. 
     SUMMARY OF THE INVENTION 
     The present invention addresses these and other drawbacks of the prior art by providing a templated evenly illuminated source for addition to such push-button devices without relying on unwanted pinpoints of light and in a manner that is pleasing to the eye, is not distracting or attention-gathering, and is an aid rather than a hindrance to regular users of such devices. The illumination method includes an electroluminescent lamp in which a light-emitting phosphor layer and a dielectric layer are sandwiched between conducting surfaces. The electroluminescent layer is activated and illuminated by an alternating current. 
     The invention includes a power supply and a thin, flexible electroluminescent planar sheet. In one preferred embodiment, the power supply comprises an electrical voltage inverter and a power source. The planar sheet is profiled on the border of the device and contains a templated series of openings placed around push buttons of the device. The planar sheet may be attached to the device by means of an adhesive matrix in the interface between the planar sheet and the surface of the device. The planar sheet has electroluminescent properties due to embedded circuitry which can be powered by the power source, such as a battery, to evenly illuminate the entire surface of the sheet, at a current of approximately 1.0 mA/sq. in. The circuitry is accessed by a terminal that receives a power clip. The power clip is connected to an electrical inverter with electrical leads. Further, additional electrical leads connect the inverter to the battery. A controlled interval or variable interval timer may be added to the circuit such that when a switch is closed, current flows to the timer and the lamp is turned on for a specified interval between arbitrarily selected high and low values. 
     The invention can be applied to any number of underlying devices. Underlying devices represent finger actuated electrical devices with push buttons which derive some benefit from being illuminated. Such underlying devices may be hand operated. Examples of such underlying devices include but are not limited to stereo and television remote controllers, keypads for security systems, telephones, computer keyboards, beepers, video games, night lights, portable emergency lighting, baby monitors, citizens band radios, money converters, control panel labels, garage door openers, hospital wall and portable intermittent and constant suction devices, intravenous pumps, oxygen wall units, digital ear and oral thermometers, walkie talkies, conventional and microwave ovens, thermostats, clock radios, answering machines, hospital bed controls, and calculators. 
     When the thin electroluminescent lamp portion of the invention is placed around push buttons of an underlying device, that device can be used under low-level illumination, or even in complete darkness. The invention can be added during the manufacturing process to make such devices usable under low-level illuminating conditions, or it can be retrofitted by the end-user to upgrade devices already in use. The planar sheet can be manufactured to glow in a variety of colors, to suit the needs of the manufacturer or end-user. 
     The present invention permits lighting an underlying device by template illumination, rather than by back lighting the device. Template illumination allows the invention to be added to preexisting devices without requiring extensive disassembly of such devices, or it may be added to newly manufactured devices. Template lighting also allows custom labels, such as telephone extension names, to be illuminated. Such labels can be added by any available method including but not restricted to sub-surface labels, screen printed or laser printed labels, adhesive fixing of pre-prepared labels, and pen-based hand labeling. 
     Additionally, the present invention allows augmentation of any existing illumination of push-button devices by bathing the surrounding templated area with an even area of illumination. Because the templated area is lighted, larger, more visible lettering can be used to aid elderly or visually impaired users of such underlying devices. Low-vision users, those whose vision cannot be corrected to generally accepted values in spite of using special magnifiers and optical devices to allow visual imaging, are helped by such lighting. A light background with dark letters offers more visibility to such users than would dark buttons illuminated with tiny pin-points of light. 
     In addition to aiding low-vision users, the present invention allows the underlying push-button device to be engulfed in an artistic glow of one of several luminous and attractive colors. Such colors can be changed to suit the needs or desires of different users, The different available colors make it practical to differentiate similar devices, such as remote controllers for two distinctive televisions. 
     Further, although the electroluminescent planar sheet can be made to display different colors of illumination by changing individual phosphors; by actuating a series of phosphors contained in the electroluminescent planar sheet, the background color of the device can be changed to accept programmatic commands when actuated by a computer-like chip. Using combinations of primary colored phosphors of red, yellow and blue, a wide range of background colors can be envisioned. When used for low-level illumination purposes, to satisfy the best scotopic mode, the electroluminescent lamp should be either of white luminescence with black printed indicia thereupon, or of pale yellow luminescence with dark navy blue indicia printed thereupon. 
     Presently available lights that can be added to such devices by the end-user involve harsh incandescent bulb-type lights. The present invention solves that problem by use of a soothing, evenly illuminated surface. Also, the light source used in the present electroluminescent invention should far outlast incandescent-type illumination sources. 
     These and other features and advantages of the invention provide significant additions and improvements to the art that are easily perceived by those skilled in these and related arts. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 depicts a typical underlying device, such as that used in operating home television sets, with a control button added for turning on the electroluminescent lamp. 
     FIG. 2 displays the basic circuitry of the invention such that a power supply module, which in the illustrated form of the invention contains a power supply and electrical inverter, is connected by electrical leads to an electroluminescent lamp overlaying push buttons of an underlying device. 
     FIG. 3 displays a basic external embodiment of the invention in side view in which the power supply/inverter pack is adhered to the bottom of an underlying device, and actuated via an on-off switch. 
     FIG. 4 represents a basic external embodiment of the invention, such that the power supply and DC to AC inverter are contained in a power supply module, which is connected to the thin electroluminescent sheet. 
     FIG. 5 depicts an end view of the underlying remote device such that the electrical connectors for accessing the electroluminescent sheet are visible. 
     FIG. 6 shows a partially internal embodiment of the invention in which an end-user can add the invention to an existing remote device. The power supply module is contained wholly within the battery compartment of the underlying device. 
     FIG. 7 shows a partially internal embodiment of the invention in which there is an option for a manufacturer to include the power supply module, consisting of the battery and inverter, wholly within the battery compartment of an underlying device. 
     FIG. 8 shows a wholly internal embodiment in which the invention is contained completely internally within an underlying device. In this conception of the invention, a manufacturer adds the invention wholly internally to an underlying remote device during the manufacturing process, such that the invention is intimately connected to the circuitry of that device. 
     FIG. 9 demonstrates the means of attachment of the power leads connecting the inverter to the planar electroluminescent lamp. The internal circuitry and layers of a typical lamp are also detailed in this figure. 
     FIG. 10 displays in schematic mode a typical inverter. Such a device may be transformer-based or chip-based. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Three embodiments of the invention are detailed in the following figures. One embodiment involves an electroluminescent device which is external to an underlying remote controller or similar device. A second embodiment of the invention is partially internal and the power supply module is contained wholly within the battery compartment of an underlying device. A third embodiment of the invention is shown in which the invention is contained completely internally within an underlying device such that the power supply module and electrical leads are wholly contained within the main compartment of an underlying device and intimately attached to the circuitry of such a device. 
     FIG. 1 depicts a typical controller device  10 , such as that used for operating home television sets, with an on-off control switch button  12  added on the left aspect for turning on the electroluminescent lamp  13 . The lamp  13  preferably comprises a thin planar sheet that develops an electroluminescent response when powered by an electrical source. In this configuration, the illumination on-off control switch button  12 , located in a knurled switch housing  15 , is placed at the left to accommodate a right handed user, who operates the button using the right thumb or middle finger. The switch button  12  is mounted in a manner such that the switch is easily accessed and yet is isolated from other controls. Also, the switch button allows the device to be lit only when a user wants it lit. The other buttons  11 , such as those used to control channel selection, are typically operated using the other thumb or index fingers. Alternately, a left-handed user may place the illumination button at the right, for more comfortable use. The illustrated form of the invention can utilize a push button, a toggle switch, a sliding switch or other such control button. 
     The electroluminescent lamp  13  features a planar sheet attached to the controller  10  using an adhesive on or at the interface  14  between the underside of the planar sheet and the upper face of the controller. It is perceived that the user will use either a permanent adhesive, or a more temporary and removable adhesive. Details of the attachment configuration are more clearly shown in FIG.  9 . The electroluminescent lamp, which can be illuminated with a variety of hues to suit user needs or preferences, allows for viewing such devices under conditions of dim lighting or even absolute darkness. 
     FIG. 2 depicts the basic circuitry of the invention, and also shows an alternate location for a switch button  27 , on a DC to AC electrical voltage inverter  26 . The invention can either be added to an underlying device during the initial manufacture, or it can be retrofitted to a pre-existing device. A battery source  20 , for example a 3 volt DC source employing two 1.5 volt AA batteries  21 , is connected to define a positive terminal  22  and a negative terminal  23 , respectively, to a standard battery connector  24 , which is in turn attached by wire leads  25  to the inverter  26 . The inverter  26  converts the 3 volts DC current to 80 volts AC. DC to AC conversion at a particular voltage, current, and frequency, for purposes of this invention, involves standard principles and is well known to practitioners in the art. The electroluminescent lamp  13 , such as Durel® 3 (Durel Corp., 2225 West Chandler Blvd., Chandler, Ariz. 85224, 602/917-6000), is operated by a voltage of between 80 and 120 volts AC. According to manufacturer specifications, brightness of the lamp at 115 V, 400 Hz is 17 to 23 ft-L. Such luminous material is thinner than a credit card and may be cut with a scissors or knife. Durel® 3 also has a screen printable surface and glows softly and evenly when lit, like that used in wristwatches like the Timex® Indiglo®. This material is available in blue-green, green, white, orange-yellow, and other custom colors. The sheet lamp material, as supplied by the manufacturer, contains distributed internal electrical circuitry for illumination purposes so that portions of the sheet can be cut off to illuminate small surfaces of applicable devices. While the lamp material is moisture resistant, it can be further protected using a plastic cover. The inverter  26  is activated by the switch button  27 , located in a knurled switch housing  31 , and connected by wire leads  28  to electrical clips  29  which mate with lamp connectors  30 . 
     The thin planar sheet of the electroluminescent lamp material  13  is shown with perforations  35  around and exposing the push buttons  11  of an underlying remote device  10 , such as the device shown in FIG.  1 . The electroluminescent lamp has a built-in circuit which is shown in FIG.  9 . Contemplated in the invention are both pre-cut templated planar sheets to fit over commercially available push-button operated devices, as well as custom-made sheets that are user-prepared and formed by scissors, scalpel, or other knife-like device. The visible surface of the electroluminescent sheet is evenly and softly illuminated in a manner such that labels can be read surrounding the push buttons of the underlying device, while the illumination is not over or under done. The resulting illumination is not overly bright or harsh to the user or others in the vicinity of the user, is not distracting to the main activity for which such a push-button device is used, does not unduly expose the user to harm by drawing attention to the use of such an underlying device, and does not result in a momentary loss of night vision. Such an underlying device is therefore illuminated by template illumination rather than by back lighting. Among advantages of template illumination are that large type can be used on customized labels so that visually-impaired users can see such devices in a superior manner to devices employing dark buttons with tiny points of light illuminating the button labels. 
     In FIG. 3, the basic external embodiment of the invention is shown. An end view of the remote controller  60  clearly shows the power supply module  40 , containing the battery source  61  and switch  62 , releasably attached to the back of the remote controller  60 . The thin planar electroluminescent lamp sheet  64  is attached with an adhesive matrix  65 , in the interface  67  between the lamp sheet  64  and the top surface  66  of the remote controller  60 , such that free movement of the push buttons  64  is allowed. 
     In FIG. 4, the power supply module  40  is shown containing a battery source  41 , switch  42 , and a DC to AC inverter  43 , connected by electrical leads  44 . When a switch  2  is closed, current flows to a timer  52  turned on for a specified interval arbitrarily elected within a range of high and low values. Additional leads  45  connect the power supply module  40  to the external connectors  46  of the planar electroluminescent sheet lamp  47 , which is cut to expose the push buttons  48  of the underlying remote control device  49 . 
     An end-on view at the bottom aspect of the remote controller  50 , is shown in FIG.  5 . The connectors at the top  46  and bottom  51  of the electroluminescent sheet allow external electrical connections to be made to the internal illumination circuitry. 
     FIG. 6 displays a partially internal embodiment of the invention in which an end-user can add the invention to an existing remote device. A typical underlying device is shown in top view  71 , side view  72 , bottom view  73 , and in a view showing the opposite side  74 . Also shown is a chip-based inverter  70  added to the side of the underlying remote device  10  operated by push buttons  11 . The illumination on-off control switch button  12 , located in a knurled switch housing  15 , is also shown mounted to the left side of the underlying device. The lamp connectors  30  of the electroluminescent lamp  13  are shown extending laterally in the top view  71 , and bent downward into slots in the case of the underlying device in the side view  72  and opposite side view  74 . The electrical clips  29  which mate with the lamp connectors  30  are connected by wire leads  28  to the inverter  70 , which is connected by additional leads  74  in the battery compartment  75  of the underlying device. In this embodiment, the invention pulls power directly from the battery source  76  of the underlying device. 
     FIG. 7 shows a partially internal embodiment of the invention in which there is an option for a manufacturer to include the power supply module  80 , consisting of the battery  76  and inverter  70 , wholly within the battery compartment  81  of an underlying remote device  82  operated by push buttons  11 . A typical underlying device is shown in top view  83 , side view  84 , bottom view  85 , and in a view showing the opposite side  86 . The illumination on-off control switch button  12 , located in a knurled switch housing  15 , is also shown mounted to the left side of the underlying device. The lamp connectors  30  of the electroluminescent lamp  13  are shown extending laterally in the top view  83 , and bent downward into slots in the case of the underlying device in the side view  84  and opposite side view  86 . The electrical clips  29  which mate with the lamp connectors  30  are connected by wire leads  28  to the inverter  70 , which is connected by additional leads  74  in the battery compartment  80  of the underlying device. The wire leads  28 ,  74  may extend either partially within the casing of an underlying device  82 , or externally to the casing and located on the side  84  of the device. When the leads are external, they consist of insulated copper wire with adhesive on one side, such as those used in children&#39;s doll houses. For an embodiment in which the leads are wholly internal, reference is made to FIG.  8 . 
     FIG. 8 shows a wholly internal embodiment in which the invention is contained completely internally within an underlying device  82  operated by push buttons  11 , and in which the power supply module  70 , consisting of the battery  76  and inverter  70 , and electrical leads  28  are also either wholly contained within the main compartment  91  or within the battery compartment  80  of the remote control device  82 , and intimately attached to the circuit board  88  of the controller device such that only the planar electroluminescent sheet  13  and a portion of its electrical clip attachments  30  are visible at the outside aspect of the controller. A typical underlying device is shown in top view  83 , side view  84 , bottom view  85 , and in a view showing the opposite side  86 . Additionally, a close-up view  92  is shown of the solderless connection of the electrical clips  29  which mate with lamp connectors  30 , and with the positive  89  and negative  90  copper leads of the circuit board  88  of an underlying device. The illumination on-off control switch button  87  is depicted at the left side of the remote device. In this conception of the invention, a manufacturer adds the invention wholly internally to an underlying remote device during the manufacturing process, such that the invention is intimately connected to the circuitry of that device. 
     FIG. 9 shows the means of attachment of the external clip  29  from the power leads  110  connecting the inverter (not shown in this figure) to the profiled edge of the planar electroluminescent lamp  13 . The Durel® 3 lamp, for example, employs electrical contact clips  29  which mate with the lamp connectors  30  at the external edge of the lamp to access the internal circuitry of the lamp and to turn on the lamp. A connector consists of a top cathodal surface  101  and a bottom anode  102 , allowing external electrical connections to the electroluminescent lamp. The Durel® 3 lamp, according to information from the manufacturer, can be accessed by silver pad leads (attached with conductive adhesive or a zero-insertion force connector), copper ribbon leads, or as in this depiction, solderless pin connectors  110 . 
     The internal circuitry and layers of this particular lamp are also detailed in FIG.  9 . The lamp is approximately 0.010″ to 0.013″ thick, formed primarily of a polyester substrate transparent electrode  103 , a colored phosphorus layer  104 , a dielectric layer  105 , a rear electrode  106 , and a rear insulator  107 . 
     FIG. 10 displays in schematic mode a typical inverter. Such a device may be transformer-based or chip-based, and the principles of operation of such an inverter are well known to those skilled in the art. The electroluminescent lamp  13  is shown with perforations  35  surrounding the push buttons  11  of an underlying device (not shown in this drawing). The electroluminescent lamp  13  is accessed by electrical clips  29  which mate with the lamp connectors  30 , which are in turn connected by wire leads  28  to the inverter  120 . The inverter  120 , shown in a box  121 , converts DC current from a battery source  122  to AC current  123 , to turn on the lamp  13  when a switch  124  is activated. 
     The principles, preferred embodiments, and mode of operation of the present invention have been described in the foregoing specification. This invention is not to be construed as limited to the particular forms disclosed, since these are regarded as illustrative rather than restrictive. Moreover, variations and changes may be made by those skilled in the art without departing from the spirit of the invention.