Abstract:
A flat-panel lamp having a light-emitting surface with an integral contact sensitive layer located over the light-emitting surface that controls the activation and deactivation of the lamp and a controller for supplying power to the lamp and responsive to a signal provided by the integral contact sensitive layer for controlling the supply of the power to the flat panel lamp.

Description:
FIELD OF THE INVENTION 
     This invention relates generally to area illumination and, more particularly, to flat-panel lights and controls thereof. 
     BACKGROUND OF THE INVENTION 
     Electroluminescent or EL panels having a large emitting surface area are thin, light-emitting devices that may be employed for illuminating a large surface, interior or exterior area, or room. The light is produced without the high temperatures associated with incandescent and fluorescent light-emitting devices. In addition since glass envelopes used for these types of lighting systems are not required for EL lighting systems, they are far less prone to breakage from contact with foreign objects. Electroluminescent (EL) lamps are created by placing a phosphor layer between two electrodes that function electrically as a capacitor. AC voltage is applied across the electrodes and light is generated which passes through the top transparent electrode. EL lamps can be as thin as 0.008″, are flexible, and are shock resistant. Flexible electroluminescent cable, sheets, and ribbons are known and can be cut to size and can include an adhesive mounting layer. 
     Area illuminators are typically controlled through wall-mounted switches, either binary or variable. Such arrangements, while simple, require additional equipment remote from the area illuminator for switching. Incandescent lamp holders that control the output of the lamp when a user touches the holder body are also known. Alternatively, EL lights may be switched on and off at a power supply or inline on the power cable. 
     Physical properties of the human body have been used to activate touch-sensitive switches that, in turn, have been used to active and deactivate lighting systems. There are four general techniques used to enable this capability. 
     Temperature—The human body is generally warmer than the surrounding air. Many elevators therefore use buttons that are sensitive to the warmth of the human finger. Also, switches using infrared detectors to sense the heat of the human body are known. 
     Resistance—The human body, being made mostly of water, conducts electricity reasonably well. By placing two contacts very close together, a finger can close an electrical circuit when touched. 
     Radio reception—Because the human body is conductive, it can act like an antenna. Some touch-sensitive switch designs simply look for a change in radio-wave reception that occurs when the switch is touched. 
     Capacitance—Conventional touch-sensitive lamps almost always use a fourth property of the human body, capacitance. The lamp, when standing by itself on a table, has a certain capacitance. This means that if a circuit tried to charge the lamp with electrons, it would take a certain number to “fill it.” When the lamp is touched by a human body, the capacitance is increased. It takes more electrons to charge both the body and the lamp, and the circuit detects that difference. It is even possible to purchase plug-in boxes that work on the same principle and can turn any lamp into a touch-sensitive lamp. 
     Many touch-sensitive lamps have three brightness settings even though they do not use three-way bulbs. The circuit changes the brightness of the lamp by changing the “duty cycle” of the power reaching the bulb. A bulb with a normal light switch gets “full power”. Rapidly switching the bulb on and off is the basic idea used to change the brightness of the lamp—the circuit uses zero percent (off), 33 percent, 66 percent and 100 percent duty cycles to control the lamp&#39;s brightness. 
     It is also known to incorporate interactive devices such as touch screens with display devices rather than area illuminators to provide pointing information as with a keyboard or mouse. Displays such as LCDs can incorporate an electroluminescent backlight that is not electronically connected to the touch screen directly and are not used for “general lighting” purposes but to illuminate the LCD display. 
     Touch screen monitors have become more and more commonplace, as their price has steadily dropped over the past decade. There are three basic systems that are used to recognize a person&#39;s touch: resistive, capacitive, and surface acoustic wave (SAW). Infrared and inductive systems, though less popular, are also known. 
     The resistive system consists of a normal glass panel that is covered with a uniformly conductive and a deformable top sheet with a similarly conductive layer. These two layers are held apart by spacers, and a scratch-resistant layer is placed on top of the apparatus. An electrical potential is placed across the two layers while the monitor is operational. When a user touches the deformable top sheet, the two conductive layers make contact in that exact spot. The change in the electrical field is noted and the coordinates of the point of contact are calculated by the computer. Once the coordinates are known, a special driver translates the touch into location information, much as a computer mouse driver translates a mouse&#39;s movements into a click or a drag. 
     In the capacitive system, a layer that stores electrical charge is placed on the glass panel of the monitor. When a user touches the monitor with his or her finger, some of the charge is transferred to the user, so the charge on the capacitive layer decreases. This decrease is measured in circuits located at each corner of the monitor. The computer calculates, from the relative differences in charge at each corner, exactly where the touch event took place and then relays that information to the touch screen driver software. One advantage that the capacitive system has over the resistive system is that it transmits almost 90 percent of the light from the monitor, whereas the resistive system only transmits about 75 percent. This gives the capacitive system a much clearer picture than the resistive system. 
     On the monitor of a surface acoustic wave system, two transducers (one receiving and one sending) are placed along the x and y axes of the monitor&#39;s glass plate. 
     Also placed on the glass are reflectors that reflect an electrical signal sent from one transducer to the other. The receiving transducer measures any disturbance by a touch event at any instant, and can locate it accordingly. The wave setup has no metallic layers on the screen, allowing for 100-percent light throughput and perfect image clarity. This makes the surface acoustic wave system best for displaying detailed graphics (other systems have significant degradation in clarity). 
     These interactive systems also differ in which stimuli will register as a touch event. A resistive system registers a touch as long as the two layers make contact, which means that it responds to any deforming object, whether a stylus or a finger. A capacitive system, on the other hand, must have a conductive input, usually a finger, in order to register a touch. The surface acoustic wave system works much like the resistive system, allowing a touch with almost any object—except hard and small objects such as pen tips. Typically, resistive systems are the least expensive, have the lowest clarity, and are most easily damaged by sharp objects. The surface acoustic wave system is usually the most expensive. However, such devices are not adapted to area illumination and are, moreover expensive, complex, and are not readily adapted to the environment and user interface. 
     A wide variety of these systems are known in the art and are described, for example, in “Being Seen Technologies Inc.” at http://www.beingseen.com/index.html, “Novatech electro-luminescent” at http://www.novael.com/index.html, “MetroMark” at http://www.metromark.com, and “Luminousfilm” at http://www.luminousfilm.com. 
     However, none of these designs provide a convenient local control for a flat-panel area illuminator that does not require additional mounting equipment and is not location specific. 
     SUMMARY OF THE INVENTION 
     In accordance with one aspect of the present invention there is provided a flat-panel lamp having a light-emitting surface with an integral contact sensitive layer located over the light-emitting surface that controls the activation and deactivation of the lamp; 
     a controller for supplying power to the lamp and responsive to a signal provided by the integral contact sensitive layer for controlling the supply of the power to the flat-panel lamp. 
     Advantages 
     The present invention provides a local, integrated control for a flat-panel area illuminator that does not require complex support circuitry. 
     These and other aspects, objects, features and advantages of the present invention will be more clearly understood and appreciated from a review of the following detailed description of the preferred embodiments and appended claims and by reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the detailed description of the preferred embodiments of the invention presented below, reference is made to the accompanying drawings in which: 
         FIG. 1  is an exploded perspective illustration of a touch light structure. 
         FIG. 2  is a perspective illustration of a touch light after the individual layers have been laminated together. 
         FIG. 3  is a perspective illustration of a touch light prior to being activated by a user. 
         FIG. 4  is a perspective illustration of a touch light being activated by the user. 
         FIG. 5  is an exploded perspective illustration of a flat-panel lighting sheet and contact sensitive means. 
         FIG. 6  is an exploded perspective illustration of a flat-panel lighting sheet and contact sensitive means. 
         FIG. 7  is a cross sectional view of a deactivated contact sensitive switch. 
         FIG. 8  is a cross sectional view of an activated contact sensitive switch. 
         FIG. 9  is an exploded perspective illustration of a flat-panel lighting sheet and contact sensitive means with the addition of an adhesive mounting layer. 
         FIG. 10  is a perspective illustration of a touch light formed into the shape of a truncated cone embossed with a graphic image. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 1 , an exploded perspective illustration of a touch light structure  10  includes a transparent contact sensitive switch layer  20 , top transparent electrode  30 , phosphor layer  40 , and bottom conventional electrode layer  50 . Power is provided to power converter  60  via power connector  70 . Power converter  60  is used to convert the power to the required voltage and frequency by power converter  60 , which is supplied to electrodes  30  and  50 . Power from converter  60  can be interrupted or enabled by transparent contact sensitive switch  20 . The phosphor layer  40  may comprise a plurality of layers such as may be found, for example, in an organic light emitting diode (OLED) device. 
       FIG. 2  is a perspective illustration of a touch light after the layers have been laminated together  80 . When top transparent electrode  30  and bottom conventional electrode  50  are energized, phosphor layer  40  emits light, which passes through transparent electrode  30  and transparent contact sensitive switch  20 . Electroluminescent or EL lighting material is manufactured so that it can be cut to shape prior to the attachment of electrical wires.  FIG. 3  is a perspective illustration of a touch light prior to being activated by a user  90  with electrical connector  70  connected to wall power outlet  100 . Flexible touch light  80  can be attached to any surface via bottom adhesive layer, not shown. 
       FIG. 4  is a perspective illustration of a touch light  80  being activated by the user  90 . User  90  finger contacts transparent contact sensitive  20  completing the circuit, causing light emission  110 . 
     Referring to  FIG. 5 , the flat-panel lighting sheet of the present invention may be constructed upon a substrate  170 . Either electrode  50  or  30  may be formed upon the substrate  170 . In one embodiment, the electrode  50  may be reflective or the substrate  170  may be reflective, the phosphor layer  40  may be formed upon the electrode  50 , the second electrode  30  is formed over the phosphor layer  40 , a cover  150  may be interposed between the second electrode  30  and the transparent contact sensitive switch  20  and may be employed to encapsulate the light-emitting portion of the flat-panel lighting sheet  10 , and the transparent contact sensitive switch formed over the cover  150  or second electrode  30 . Light  110  from the light emitting phosphor layer  40  may be emitted through the electrode  30  and transparent contact sensitive switch  20 . In another alternative, the electrode  30  may be formed upon one side of a transmissive rather than reflective substrate  170 . 
     Referring to  FIG. 6 , the phosphor layer  40  is formed upon the electrode  30 , and the electrode  50  is formed upon the phosphor layer  40 . An encapsulating cover  150  may be positioned over the electrode  50 . The contact sensitive switch  20  may be formed upon the other side of the transmissive substrate  170 . Light from the light-emitting phosphor layer  40  may be emitted through the electrode  30 , the transmissive substrate  170 , and the transparent contact sensitive switch  20 . 
     The touch light of the present invention may be either rigid or flexible. If the touch light is rigid, it may be formed upon a rigid substrate or may include a rigid cover made of, for example, glass or metal. If the touch light is flexible, it may be formed upon a flexible substrate or may include a flexible cover made of, for example, plastic or metal foil. A flexible cover or substrate may also be employed with a rigid substrate or cover, respectively. If the touch light is flexible, it may be placed conformably over surfaces that may not be flat to provide a curved light-emitting surface. 
     Referring to  FIG. 7 , the contact sensitive switch  20  may itself be a resistive switch composed of a pair of electrodes  115  and  120  deposited on supporting structures  130  and  140 , at least one surface of which is flexible, separated by spacers  160 . The electrodes  30 ,  50  may include metal, metal oxides, or metal alloys. For example, a thin coating of aluminum, silver, and/or indium tin oxide may be provided on a supporting structure  130  or  140 . The spacers  160  may be formed of a variety of appropriate materials and may take a variety or suitable shapes. For example, but not by way of limitation, the material may include polymers and/or glasses having cylindrical or spherical shapes. In a further embodiment the spacers  160  may be integrally formed as a part of supporting structure  130  or  140 . 
     As shown in  FIG. 8 , deformation of flexible electrode  120  results in a connection between electrodes  120  and  115  allowing a current to pass and thereby actuating a relay to control the flat-panel lighting sheet. Unlike conventional resistive touch screens, however, the contact sensitive switch  20  of the present invention requires only the detection of a contact, not the location of the contact. Hence, a much simpler structure may be employed wherein the electrodes  115  and  120  may not be completely uniform and additional corrective conductors located around the periphery of the contact area are not required and scanning and conversion circuitry within a controller are not necessary. The detection of a contact may simply be accomplished by detecting a current flow between the electrodes. 
     The contact sensitive switch may be constructed upon either the substrate  170  (as shown in  FIG. 6 ) or cover  150  (as shown in  FIG. 5 ) encapsulating the electrodes  30  and  50 , and the phosphor layer  40 . In a preferred embodiment, one of the two electrodes of a two-electrode contact sensitive switch  20  is formed upon a common substrate or a common cover of the light emitting elements as is shown in  FIGS. 5 and 6 . 
     The controller  60  of the present invention may be employed to operate the touch light in a variety of ways. For example, sequentially detected contacts may cause the controller to incrementally cause the display to become brighter or dimmer. Alternatively, the length of time that a contact persists may be employed to determine the brightness of the touch light. 
     As shown in  FIG. 9 , one embodiment of the present invention may employ an adhesive layer  180  to attach the touch light to another surface or to integrate it within a surface. For example, the touch light may be permanently affixed to a surface by an adhesive such as glue, for example an epoxy. Alternatively, the touch light may be temporarily or removably affixed to a surface, for example with removable adhesives or highly plasticized polyurethanes. 
     Mechanical means of affixing a touch light to a surface may be employed, for example with Velcro or flanges designed to receive a touch light into a recess. Alternatively, magnetic means may be employed in which a magnet is affixed to the touch light and the surface to which it is affixed is metal or in which a metal layer is provided on the touch light and the surface has a magnet. Pneumatic layers, for example suction cups or vacuums may be employed. Mounting stanchions having flanges or serving as a cover or substrate may be employed. Static electrical attraction means using oppositely charged surfaces may also be used. 
     The touch light of the present invention may be manufactured in a continuous process, cut into sheets, and sealed. The shapes into which the touch light is cut may be formed into three dimensional shapes such as cones  190 , cylinder, cubes, and other geometric shapes, for example as shown in  FIG. 10 . The shapes may be formed by lamination onto underlying substrates or through vacuum formation. The surfaces of the touch light may be embossed with decorative or functional shapes  195 . Moreover, the area of a touch light may include regions that are not light emissive to form information-bearing area illuminators, for example signs. 
     The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention. 
     PARTS LIST 
     
         
           10  touch light panel 
           20  transparent touch sensitive switch layer 
           30  top transparent electrode layer 
           40  phosphor layer 
           50  bottom conventional electrode layer 
           60  power converter/control circuit 
           70  power connector 
           80  laminated touch light panel structure 
           90  user&#39;s hand 
           100  wall power outlet 
           110  light emission 
           115  electrode 
           120  electrode 
           130  supporting structure 
           140  supporting structure 
           150  cover 
           160  spacer 
           170  substrate 
           180  adhesive layer 
           190  shape 
           195  decoration