Abstract:
The present invention is directed to a power control wiring device that includes an electronic switch circuit that energizes the electrical load in accordance with a timing regulation signal. A timing regulation circuit includes a primary timing regulation circuit and an auxiliary timing regulation circuit. The circuit is adjustable between a minimum power setting and a maximum power setting to thereby generate an adjustable primary timing regulation signal. The timing regulation circuit also generates an auxiliary timing regulation signal to thereby reduce power consumption. A primary manual power control mechanism is configured to adjust the primary timing regulation circuit between the minimum power setting and the maximum power setting. An auxiliary manual power control mechanism is configured to trim the maximum power setting in accordance with the selectable trim adjustment, the at least one auxiliary manual power control mechanism being user accessible.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation of U.S. patent application Ser. No. 11/294,167 filed on Dec. 5, 2005 now U.S. Pat. No. 7,758,234, U.S. patent application Ser. No. 11/294,167 is a continuation-in-part of U.S. patent application Ser. No. 11/242,406 filed on Oct. 3, 2005 now U.S. Pat. No. 7,285,721, the contents of which are relied upon and incorporated herein by reference in their entirety, and the benefit of priority under 35 U.S.C. §120 is hereby claimed. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to electrical devices, and particularly to electrical lighting devices suitable for commercial and residential applications. 
     2. Technical Background 
     The typical layout of a room, whether it is a public space, a living space or a commercial space, provides a wall light switch disposed adjacent to the point of entry. In a scenario that most people are familiar with, a person crossing the threshold of a darkened room will usually attempt to locate the wall switch and turn the wall switch to the ON position before entering. Sometimes the wall switch is not located in this position and the person seeking access to the room must search for the light switch. The person searching for the wall switch is required to navigate around objects such as tables and chairs. Usually, a person entering the room attempts to “feel” their way around the room. If an object is disposed relatively low to the floor surface the person may trip over it and suffer an injury. Accordingly, searching a room in this manner is not recommended because of the aforementioned safety issues. The scenario recounted above is also applicable to (but not limited to) other types of spaces such as corridors, theater aisles, stairways, patios, garages, ingress/egress areas, out-buildings, outdoor pathways and the like. 
     As noted above, there are situations where a light switch is not available, or is not readily available. There are other situations where the person entering the darkened room is disinclined to turn the lights ON as a matter of courtesy. Several examples immediately come to mind. A person entering a darkened theatre would expect to incur the wrath of his fellow patrons if he turned the theatre lights ON while finding a seat. In another situation, a person may desire to temporarily enter a room occupied by a person who is sleeping. For example, a parent may not want to check on the condition of a sleeping infant, or tend to someone who is ill, without having to turn the lights ON and so disturb their sleep. 
     In one approach that has been considered, a portable lighting device may be inserted into an electrical receptacle located in the room and function as a temporary lighting device. While this arrangement may provide adequate illumination and temporarily mitigate a potentially unsafe condition, it has certain drawbacks associated with it. Temporary lighting devices are usually aesthetically unappealing and have a makeshift look and feel. On the other hand, a temporary lighting device may be plugged into the receptacle for an extended period of time to meet the recurring lighting need. The user may attempt to address this problem by unplugging the temporary lighting device during daylight hours if the space admits natural light. However, once the temporary lighting device is unplugged from the receptacle there is the possibility that it will become lost, misplaced, or damaged from excessive handling. Of course, the steps of inserting and removing the device in response to the daily cycle is not a solution in internal spaces lacking access to sunlight. 
     In another approach that has been considered, a light element may be disposed in a wiring device in combination with another functional element such as a receptacle or a light switch. The wiring device is subsequently installed in a wall box or mounted to a panel. While this approach obviates some of the drawbacks described above, there are other drawbacks that come into play. Conventional permanent lighting elements such as incandescent and neon lights have a relatively short life expectancy of only a few years and, therefore, require periodic servicing and/or replacement. This problem is exacerbated by the fact that the light is typically hard-wired to power contacts disposed in the wiring device. As such, the light element is permanently ON, further limiting the light elements life expectancy. 
     In yet another approach that has been considered, the aforementioned drawbacks are addressed by providing a light sensor, and the associated circuitry, to control the light element. When the sensor detects the ambient light level falling past a certain point, the control circuit turns the light element ON. One design problem associated with using a light sensor to selectively actuate the light element relates to providing a proper degree of isolation between the light sensor and the light element. Conventional devices solve the problem by separating the light sensor and the light element by as great a distance as possible. As such, conventional devices are typically arranged such that the lens covering the light element is disposed in one portion of the wiring device cover and the sensor element is disposed in a second portion of the cover, with sufficient space therebetween. If the wiring device includes another functional element such as a receptacle, the sensor may be disposed between the receptacle and the light&#39;s lens cover. Because the light sensor must be disposed a sufficient distance away from the light element, it necessarily requires that the lighting assembly be reduced in size to fit the wiring device form factor. Accordingly, conventional devices of this type often fail to provide an adequate amount of illumination for the intended application and, therefore, do not address the safety concern in a satisfactory manner. 
     What is needed is an electrical device configured to address the drawbacks and needs described above. In particular, a light emitting wiring device is needed that provides a sufficient amount of illumination when the ambient light in a given space falls below a safe level. The wiring device must maximize the effective area of illumination without sacrificing sensor isolation. What is also needed is an electrical wiring device that addresses the safety issues described above, while at the same time, providing user-accessible adjustment mechanisms with an eye toward energy efficiency. 
     SUMMARY OF THE INVENTION 
     The present invention addresses the needs described above by providing an electrical device configured to address the drawbacks and needs described above. In particular, the device of the present invention provides a sufficient amount of illumination when the ambient light in a given space falls below a safe level The present invention also provides an electrical wiring device that addresses the safety issues described above while, at the same time, providing user-accessible adjustment mechanisms with an eye toward energy efficiency. 
     One aspect of the present invention is directed to a power control wiring device that includes at least one terminal configured to be connected to a source of AC power. An electronic switch circuit is coupled to at least one electrical load. The electronic switch element provides a switch actuation signal selectively energizing the electrical load during a portion of an AC cycle in accordance with a timing regulation signal. A timing regulation circuit is coupled to the at least one terminal and the electronic switch circuit. The timing regulation circuit is configured to generate the timing regulation signal. The timing regulation circuit includes a primary timing regulation circuit adjustable between a minimum power setting and a maximum power setting to thereby generate an adjustable primary timing regulation signal. The timing regulation circuit includes an auxiliary timing regulation circuit configured to generate an auxiliary timing regulation signal that trims the maximum power setting in accordance with a selectable trim adjustment to thereby reduce power consumption relative to the maximum power setting. The timing regulation signal is a combination of the primary timing regulation signal and the auxiliary timing regulation signal. A primary manual power control mechanism is configured to adjust the primary timing regulation circuit between the minimum power setting and the maximum power setting. At least one auxiliary manual power control mechanism is configured to trim the maximum power setting in accordance with the selectable trim adjustment, the at least one auxiliary manual power control mechanism being user accessible. 
     Additional features and advantages of the invention will be set forth in the detailed description which follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the invention as described herein, including the detailed description which follows, the claims, as well as the appended drawings. 
     It is to be understood that both the foregoing general description and the following detailed description are merely exemplary of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate various embodiments of the invention, and together with the description serve to explain the principles and operation of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view of light emitting wiring device in accordance with an embodiment of the present invention; 
         FIG. 2  is a rear view of the light emitting wiring device depicted in  FIG. 1 ; 
         FIG. 3  is a perspective view of the light emitting wiring device depicted in  FIG. 1 ; 
         FIG. 4A  is a longitudinal cross-sectional view of the light emitting wiring device shown in  FIG. 1 ; 
         FIG. 4B  is a cross-sectional perspective view of the light emitting wiring device shown in  FIG. 1 ; 
         FIG. 5  is a transverse cross-sectional view of the light emitting wiring device shown in  FIG. 1 ; 
         FIG. 6  is an exploded view of the light emitting wiring device shown in  FIG. 1 ; 
         FIG. 7  is a front view of light emitting wiring device in accordance with a second embodiment of the present invention; 
         FIG. 8  is a front view of light emitting wiring device in accordance with a third embodiment of the present invention; 
         FIG. 9  is a schematic diagram of the light emitting wiring device in accordance with the present invention; 
         FIG. 10  is a schematic diagram of the light emitting wiring device in accordance with another embodiment of the present invention; 
         FIGS. 11A-D  are timing diagrams illustrating the operation of a light emitting wiring device having false turn-off avoidance capabilities; 
         FIG. 12  is a schematic diagram of the light emitting wiring device in accordance with yet another embodiment of the present invention; 
         FIG. 13  is a schematic diagram of the light emitting wiring device in accordance with yet another embodiment of the present invention; and 
         FIG. 14  is a front view of a cover plates usable with the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the present exemplary embodiments of the invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. An exemplary embodiment of the light emitting wiring device of the present invention is shown in  FIG. 1 , and is designated generally throughout by reference numeral  10 . 
     As embodied herein, and depicted in  FIG. 1 , a front view of light emitting wiring device  10  is shown. Device  10  includes an illumination lens  12  disposed over substantially all of the surface area that is accessible to a user after installation. The illumination lens  12  may be transparent, translucent and/or apertured. A lamp assembly is disposed behind illumination lens  12 . The lens  12  is configured to direct the light that is emitted by the lamp assembly into the space that requires illumination. The illumination lens  12  may be designed to diffuse the light emitted from the lamp, or direct the light such into a predetermined region of space. 
     Device  10  includes mounting tabs  14  that are used to affix the device to an outlet box, panel, wall, or some other structural element. After the light emitting wiring device  10  is installed, a cover plate (not shown) is attached to either the device, an outlet box, or a panel, depending on the arrangement. The light emitting wiring device shown in  FIG. 1  includes an effective area of illumination, i.e., the surface area of lens  12 , that encompasses substantially all of the area provided by a standard sized wall plate opening. See, for example, wall plate openings having the dimensional characteristics provided by the opening defined by the ANSI/NEMA WD6 standard. Those of ordinary skill in the art will understand that wall plates conforming to the aforementioned standard are ubiquitously employed. On the other hand, a multi-gang cover plate that accommodates device  10  and one or more additional wiring devices disposed in a multi-gang box may also be employed. 
     As shown in  FIG. 1 , an aperture configured to accommodate an ambient light sensor lens  16  may be disposed in lens  12 . As noted above, one of the problems associated with using a light sensor to selectively actuate a light element in a wiring device relates to providing a proper degree of isolation between the light sensor and the light element. In conventional devices the requisite isolation is achieved by providing a physical separation between the lens and the sensor. As noted, this limits the surface area of the lens. The present invention overcomes this limitation. Accordingly, an ambient light sensor assembly is configured to receive ambient light via the sensor lens  16  disposed in a portion of lamp lens  12 . Of course, the lamp is controlled by the light sensor which activates the lamp in response to a predetermined ambient light luminosity. When the luminosity is below a predetermined threshold, the lamp assembly is energized and light is emitted. 
     Those of ordinary skill in the art will understand that ambient light sensor lens  16  may be implemented as an integral part of lens  12 . In yet another embodiment, sensor lens  16  may be disposed within an opening of the cover plate and/or lens  12 . 
     Referring to  FIG. 2 , a rear view of the light emitting wiring device  10  is shown. Device  10  may be connected to a source of electrical power by way of terminals  20 . Terminals  20  may be implemented using screw terminals, wire lead terminals, push-wire terminals, back-wire terminals, composite terminals, or any suitable means. For residential, commercial and institutional applications, electrical distribution systems are commonly rated about 120 VAC or 240 VAC. Wiring device  10  may include one or more electrical circuits configured to operate at either 120 VAC, 240 VAC, or both. This feature is implemented by way of tab element  22 , which is used to configure device  10  for operability at either 120 VAC or 240 VAC. When tab element  22  is inserted, the circuits disposed in device  10  are coupled. When tab element  22  is removed, the circuits operate independently. Reference is made to co-pending U.S. patent application Ser. No. 10/729,566, filed Dec. 5, 2003, which is incorporated herein by reference as though fully set forth in its entirety, for a more detailed explanation of tab element  22 . 
     The rear portion of device  10  also includes a plurality of vents  24 . The vents  24  allow the heat generated by the lamp assembly and the circuitry to escape device  10  and dissipate in a safe manner. 
     Referring to  FIG. 3 , a perspective view of the light emitting wiring device  10  is shown with the illumination lens  12  removed. Lamp elements  30  are disposed behind illumination lens  12  and inside of reflector element  32 . Sensor assembly  60  is disposed along an edge portion of the reflector element  32 . In one embodiment, at least a portion of sensor assembly  60  is integrally formed as a part of the reflector element  32 . Sensor assembly  60  includes a sensor  62  (not shown in  FIG. 3 ) physically coupled to a printed circuit board disposed under the reflective element  32  by elongated structure  66 . A sensor aperture is formed in elongated structure  66 . The sensor aperture is formed to accommodate sensor lens  16 . Sensor assembly  60  will be described in more detail in the discussion of  FIG. 5 . 
     It will be apparent to those of ordinary skill in the pertinent art that modifications and variations can be made to reflector element  32  of the present invention depending on the shape and material used in fabricating the element. Reflector  32  includes a base member that accommodates lamp elements  30 . Surrounding the base member is a reflective hood. For example, the reflective hood may be optically configured to provide a predetermined light distribution. In one embodiment, the reflective hood may be a parabolic design having the lamps disposed at a focal point of the reflector. The reflective hood may also be configured as a modified parabolic design, a concave shape, or in the “bath tub” shaped configuration shown in  FIG. 3 . 
     Those of ordinary skill in the art will also understand that reflector  32  may be formed from any suitable material such as plastic or metallic materials. Reflector  32  is furnished with a reflective surface  34  that directs light emitted by the lamps  30  into the illuminated space. If the reflector  32  is formed from a metallic material such as aluminum, surface  34  is simply the material itself, i.e., polished aluminum. On the other hand, if the reflector  32  is formed from a plastic material, surface  34  may be formed by depositing a suitable reflective finish thereon. In one embodiment, a reflective surface may be painted on reflector element  32 . However, any suitable finish may be applied to the reflector element using any suitable application technique. 
       FIG. 4A  provides a longitudinal cross-sectional view of the light emitting wiring device  10  shown in  FIG. 1 . The arrangement of reflector element  32 , lamp elements  30 , and lens cover  12  provides a geometrical relationship causing substantially uniform light to be emitted from lens  12 . Illumination lens  12  includes a substantially smooth outer surface  46  that is easily cleaned by the user. The inner surface  44  includes an array of convex lenses. As shown, the lens array covers substantially all of the effective surface illumination area of device  10 . The individual lenslets that comprise lens  12  may be convex lens elements. In another embodiment, the lens elements may be of a parabolic, pyramidal, or polygonal shape geometry. Those of ordinary skill in the art will also understand that lens array  12  may be of any suitable type and be configured as a fresnel lens array or as a lenticular lens array, depending on the desired illumination pattern. The inventors have found that the uniformity of the illumination beam becomes acceptable when the lens density of lens array  12  is at least 9×9 lenslets per square inch, i.e., 81 lenslets per square inch. Of course, the greater the density of lenslets the more uniform the illumination beam becomes. 
     The longitudinal cross-sectional profile of outer surface  46  may be arcuate such that a center portion of outer surface  46  extends a vertical distance “a” from the edge of lens  12 . In another embodiment, both the longitudinal cross-sectional profile and the transverse cross-sectional profile are arcuate. Those of ordinary skill in the art will appreciate that as the degree of curvature increases in each direction, i.e., in the transverse and longitudinal directions, the illumination beam becomes relatively broader. In other words, when dimension “a” is zero, surface  46  is substantially planar and the individual light beams in the illumination pattern are substantially parallel to central lens axis “c”. However, when the degree of curvature increases in a given direction, the individual light beams diverge from central axis “c” and the cross-sectional beam coverage area increases accordingly. Of course, the present invention contemplates variations in the cross-sectional area of the beam in accordance with the application. 
     It will be apparent to those of ordinary skill in the pertinent art that modifications and variations can be made to lamp elements  30  of the present invention depending on the illumination properties and the life expectancy of the individual lamp elements. For example, the lamp elements shown in  FIGS. 1-4  are LED elements that have a typical life expectancy of at least ten years. Those skilled in the art will understand that similar light sources may be employed accordingly. Lamps  30  are chosen to have a viewing angle of at least about 40 to 80 degrees (light output diminishes considerably outside of the viewing angle.) Through experimentation it has been discovered that the distance “d” between lamps  30  and the inside surface  44  of illumination lens  12  should be greater than about 0.5 inches for uniform light dispersion. 
     As a result of the arrangement, design, and selection of the reflector  32 , lamp elements  30 , and illumination lens  12 , the present invention provides approximately a three-fold improvement over conventional devices; the illumination output being about 4 foot-candles compared to about 1.5 foot-candles after one (1) minute of operation. 
     Referring back to  FIG. 4A , lamp elements  30  may be coupled to circuit board  40  using any suitable means, such as, for example, soldering. Some of the circuit components  42  used in the circuitry disposed in device  10  may also be disposed on circuit board  40 . The cross-sectional view of device  10  also reveals that mounting tabs  14  are integrally formed end portions of strap assembly  48 . Strap assembly  48  in fabricated from a conductive material such as steel, plated steel, anodized steel, or other such suitable materials. Ground terminal  50  is connected to strap assembly  48  and provides for the electrical connection of a ground wire. Thus, the strap assembly  48  is at ground potential when device  10  is installed and ground terminal  50  is properly connected to ground. 
     The light emitting electrical wiring device  10  of the present invention is substantially enclosed by illumination lens cover  12 , rear housing member  52 , and strap assembly  48 . Strap assembly  48  conforms to an exterior surface of the rear housing member  52 , forming a back cover sub-assembly. When lens cover  12  is pressed against the back cover sub-assembly, snap-in elements  54  engage strap assembly  48  and rear housing member  52  is captured between strap assembly  48  and lens cover  12 . 
     In another embodiment, the mounting tabs  14  are formed from a non-conductive material and may be formed as an integral part of the rear housing member  52 . In this embodiment, lens cover  12  and rear housing member  52  are configured to snap together. Accordingly, strap assembly  48  may be eliminated since it is no longer being relied upon to mate with lens cover  12 . 
       FIG. 4B  is a cross-sectional perspective view of the light emitting wiring device  10  shown in  FIG. 4A .  FIG. 4A  shows the cross-section of  FIG. 4A  rotated by a predetermined angular amount from axis “c”. This view shows a three-dimensional view of the lens array disposed in rear surface  44  of lens cover  12 . This view also illustrates that the various electrical components employed in device  10  may be coupled to either side of circuit board  40 . As those of ordinary skill in the art will appreciate, electrical components may be provided in what are commonly referred to as through-hole configurations or as surface mount devices. 
       FIG. 5  is a transverse cross-sectional view of device  10  as shown in  FIGS. 1-4 .  FIG. 5  provides a detailed view of sensor assembly  60 . Sensor assembly  60  includes an elongated structure  66  that serves several functions. Elongated structure  66  serves to house ambient light sensor  62  in a hollow portion thereof. As noted previously, structure  66  may be formed as an integral portion of reflector element  32 . Elongated structure  66  also serves as a means for mechanically coupling ambient light sensor  62  to circuit board  40 . Accordingly, structure  66  serves to position sensor  62  as near as possible to the outer surface  46  of lens cover  12 . At the same time, structure  66  forms a conduit for the electrical leads and connections between sensor  62  and circuit board  40 . Elongated structure  66  includes a spacer element  64  disposed therein. Spacer element  64  is employed to precisely position the ambient light sensor  62  within structure  66 . 
     As noted above, elongated structure  66  is hollow and includes an isolation collar  68 . Collar  68  forms an aperture that accommodates sensor lens  16 . The position of elongated structure  66  and the aperture formed in collar  68  is precisely aligned with a corresponding through-hole portion  120  formed in lens cover  12 . Sensor lens  16  is configured to conduct and focus incident ambient light onto the active portion of ambient light sensor  62 . 
     Isolation collar  68  is also prevents any light emitted by lamps  30  from being directed toward sensor  62 . Of course, the detection of any such emissions would provide light sensor circuitry with a false indication of the true ambient light levels and would improperly de-energize lamps  30 . 
     In addition to isolation collar  68 , the present invention uses several additional techniques to isolate sensor  62  from light emitted by lamps  30 . As noted above, surface  34  may include a coated layer that reflects light from the lamps toward illumination lens  12 . The coated layer serves a dual purpose of directing light toward the cover lens  12  and preventing the light generated by lamps  30  from penetrating the surface of elongated structure  66  and contaminating sensor  62 . 
     Isolation may also be achieved by applying an opaque layer of material to the interior surface of structure  66 . This interior layer of material also prevents light from contaminating sensor  62 . 
     Another technique employed by the present invention to implement isolation between the lamps  30  and the sensor  62  relates to the implementation of sensor lens  16 . As noted previously, light sensor lens  16  is implemented as a separate component relative to illumination lens  12 . This implementation is significant because the refractive index interface between lens  12  and the interior region formed between lens  12  and reflector  32  would cause some of the incident light striking surface  44  to reflect back toward sensor  62 . However, because the present invention separates lens  16  from lens  12 , any incident light reflected from surface  44  will be directed toward collar  68  instead of toward sensor  62 . On the other hand, only ambient light is directed into lens  16  toward sensor  62 . 
     Lens  16  includes other light isolation features as well. As shown in  FIG. 5 , lens  16  is recessed relative to the outer surface  46  of lens cover  12 . In another embodiment of the present invention, sensor lens  16  is recessed below inner surface  44  of the illumination lens cover  12 . The isolation is further enhanced by collar  68  which is disposed between lens cover  12  and sensor lens  16 . On the other hand, the use of collar  68  may allow sensor lens  16  to be eliminated from the design. The lens array  44  may be extended to cover the region above the ambient light sensor  62 . One benefit to the latter approach relates to a more uniform outer surface  46 . This may improve the aesthetic appearance of the device. Further, because the front cover  12  does not have an aperture disposed therein for sensor lens  16 , device  10  may be more easily cleaned. 
     Those skilled in the art will understand that the aforementioned isolation methods may be used alone or in combination with one or more of the other isolation methods. 
     Referring to  FIG. 6 , an exploded view of the light emitting wiring device shown in  FIG. 1  is provided. As noted above, strap assembly  48  is inserted into a corresponding portion of rear body member  52  to form a back cover for device  10 . Printed circuit board  40  is disposed in the back cover portion and is electrically coupled to exterior connection terminals  20 . Spacer  64  and sensor are shown as being connected to printed circuit board  40  in this view. Reflector element  32  and integrally formed elongated structure  66  are disposed over printed circuit board, with sensor  62  and spacer  64  being inserted inside elongated structure  66 . Light sensor lens  16  is also inserted into the aperture formed by collar  68 . Finally, lens cover  12  is disposed over the entire assembly such that snap elements  54  align with corresponding mating structures formed in strap assembly  48 . After said alignment, lens cover  12  is pressed against the assembly and snap elements  54  engage the strap assembly  48  to complete the process. 
     As embodied herein and depicted in  FIG. 7 , a front view of light emitting wiring device in accordance with a second embodiment of the present invention is shown. The light emitting device  10  of this embodiment provides a lens cover  12  that occupies only a portion of the user accessible surface of device  10 . In this embodiment, the light emitting portion of device  10  may include one or two lamp elements  30  (not shown). The remaining portion of device  10  includes a wiring device  100 . The wiring device may be a receptacle (as shown) or any suitable wiring device or devices, such as switches, protective devices such as transient voltage surge suppressors (TVSSs), surge protective devices (SPDs), ground fault circuit interrupters (GFCIs), arc fault circuit interrupters (AFCIs), power control devices such as light dimmers, proximity sensors, motor controls, or fan speed controls. Reference is made to U.S. patent application Ser. No. 10/998,369, filed Nov. 11, 2004 and titled Electrical Device With Circuit Protection Component and Light, which is incorporated herein by reference as though fully set forth in its entirety. Note that light sensor lens  16  is disposed in a portion of the wiring device  100 . Those of ordinary skill in the art will understand that the sensor  62 , and sensor lens  16 , may be disposed in the surface area of cover lens  12  as disclosed previously. 
     As embodied herein and depicted in  FIG. 8 , a front view of light emitting wiring device  10  in accordance with a third embodiment of the present invention is shown. This embodiment is similar to the one shown in  FIG. 7  with the exception that a proximity detecting device  200  replaces and occupies the space previously occupied by wiring device  100  of  FIG. 7 . Proximity detecting device  200  is configured to detect a human presence within a predefined zone proximate the installed device  10 . Proximity sensing device  200  is operatively coupled to the lamps  30  disposed behind illumination lens  12 . The proximity detecting device  200  causes the lamps  30  to emit light when a human presence is detected. 
     In one embodiment of the present invention, the proximity detecting device  200  includes a motion detector that activates the lamp assembly in response to the movement of a person or object in the vicinity of device  10 . This feature is energy efficient in that the lamp assembly is only activated when needed. The movement of a person or object may be detected by sensing step changes in ambient luminosity. A step decrease in luminosity may indicate that a person or object is entering the vicinity of the hallway light device and preventing the ambient light from reaching the light sensor. The light sensor reacts by actuating the lamp assembly in device  10 . Once the person leaves the area, the light sensor experiences a step increase in luminosity, and the lamp assembly in device  10  is deactivated. 
     In another embodiment of the present invention, the proximity detecting device  200  includes a proximity light source that emits either visible or non-visible light, such as infrared light. When a person or object enters into the path of the light, the light is reflected back to the ambient light sensor. The lamp assembly is energized to emit light if the reflected light exceeds a predetermined threshold. Once the reflected light decreases below the threshold level, the lamp assembly is de-energized. The proximity light source/sensor may de-energize the lamp assembly if the amount of reflected light is less than a predetermined threshold or if there a predetermined rate of reduction in the amount of reflected light such that the lamp emits light only when there is a human need. 
     As previously discussed, the proximity detector is relatively energy efficient. Another reason for employing a proximity detector is to prevent false turn-off conditions from occurring when the lamp assembly is energized in response to darkened ambient lighting conditions. A false turn-off condition refers to instantaneous variations in the ambient light level that occur when a person or object approaches the light emitting wiring device and light emitted from a relatively remote source is reflected off of the individual into the ambient light sensor such that the incident light is greater than the sensor threshold even though the ambient conditions have not changed. Under these conditions the ambient light detector responds by turning the lamp assembly OFF. Once the reflection ceases, the light is reenergized. Under certain traffic conditions device  10  may cycle between the ON and OFF state in accordance with the reflected pattern. The so-called false turn-off condition may be avoided by employing a proximity detector. The proximity detector is configured to override the ambient light detector if the ambient light detector is in the act of detecting a darkened ambient condition. As a result, the lamp(s) continue to emit light even though a person or object has entered into close proximity to the device. 
     It will be apparent to those of ordinary skill in the pertinent art that modifications and variations can be made to proximity detector  200  of the present invention depending on the nature of the sensor. In addition to infrared devices and motion detectors, the proximity sensor of the present invention may be implemented using any suitable means such as a thermal sensor configured to detect heat generated by a human body, or an acoustic sensor. The acoustic sensor may be also configured to detect step changes in reflected sounds generated from a transducer disposed in the device. Detector  200  may include both a thermal detector and an acoustic detector. The two detectors are coordinated so as to even detect a relatively stationary human presence and a human presence behind a wall or barrier. 
     As embodied herein and depicted in  FIG. 9 , a schematic diagram of a circuit  900  disposed in light emitting wiring device  10  is shown. As is known in the art, device  10  is installed by connecting wiring terminals  20  to a source of voltage. A surge suppression device or spark gap may be employed to protect circuit  900 . By way of a non-limiting example, circuit  900  includes movistor  414  disposed across terminals  20 . Lamps  30  are turned ON and OFF by control transistor  400 . Control transistor  400  is turned ON when the voltage to zener diode  402  is greater than the rated zener voltage. Zener diode  402  is governed by voltage divider  404 . Voltage divider  404  is powered by the source voltage provided by terminals  20 . The ambient light sensor  62  is disposed in one of the legs of the voltage divider. 
     As those of ordinary skill in the art will appreciate, the resistance of the ambient light sensor  62  varies with the incident ambient light. Accordingly, the voltage provided by divider  404  to zener diode  402  varies in accordance with the incident ambient light. When the ambient light levels are relatively low, the voltage applied to zener diode  402  is greater than the zener voltage, control transistor  400  is turned ON, and lamps  30  are energized. On the other hand, when the ambient light level is relatively high, the resistance of sensor  62  causes the voltage that is applied to zener diode  402  to be less than the zener voltage. Accordingly, control transistor  400  is turned OFF and the lamps  30  are deenergized. 
     When the source voltage is AC, the circuit of  FIG. 9  provides an emitted light pattern that is inversely proportional to the ambient light such that device  10  emits more light when the ambient light levels are lower and less light when the ambient light level is relatively higher. As noted above, the applied voltage to zener diode  402  is a function of the resistance of ambient light sensor  62 . Since the voltage divider  404  is coupled to the source voltage, the voltage to zener  402  is additionally dependent on the instantaneous value of the source voltage. For example, when the ambient light level is relatively high, the instantaneous AC voltage is greater than the zener voltage only when it approaches 90 degrees in the cycle. Accordingly, lamps  30  are on only for a brief duration of each AC line cycle. When the ambient light levels are very low, i.e., in a completely darkened room, the resistance of ambient light sensor  62  is such that the voltage applied to the zener diode  402  is greater than the zener voltage from about 0 to 180 degrees. Thus, lamps  30  are energized during that portion of the AC cycle from approximately 0 degrees to 180 degrees. Thus, there is an inverse relationship between the duty cycle and the ambient light level. 
     In an alternate embodiment of the present invention, voltage divider  404  receives voltage from a pure DC source. Since the lamps  30  are no longer illuminated by way of a variable AC duty cycle, they are either ON or OFF on the basis of the value of the variable resistance of light sensor  62 . Accordingly, lamps  30  are energized when the variable sensor resistance, in conjunction with voltage divider  404 , provides a voltage in excess of the zener voltage of diode  402 . 
     Since room spaces vary in size, object arrangement, color, and usage, the desired illumination of light emitting wiring device  10  may vary. Accordingly, users may desire a light emitting device  10  that features a user selectable ambient light threshold that corresponds to the illuminated space. Accordingly, circuit  900  includes a lamp illumination level control mechanism as embodied by potentiometer  406 , potentiometer  408 , or potentiometer  410 . The potentiometers may be disposed in the voltage divider and are configured to selectively vary the voltage divider output. In one embodiment, the potentiometers are disposed inside the device  10  enclosure and are only adjustable at the factory. As such, device  10  will have a predetermined illumination rating that is not adjustable after leaving the factory. The commercial outlet that carries device  10  may sell various devices having differing illumination levels preset at the factory. In an alternate embodiment of the present invention the potentiometers are user accessible, and hence, user adjustable. As those of ordinary skill in the art will appreciate, the user accessible potentiometers may be adjusted using any suitable means. For example, the variable resistance may be adjusted using tools such as screwdrivers, or by way of a control lever or dial. 
     Those of ordinary skill in the art will appreciate the inherent energy saving features of potentiometers  406  and  408 . Potentiometer  408  is disposed in the upper leg of voltage divider  404 . When potentiometer  408  is zeroed out the instantaneous voltage from the AC voltage source that is presented to zener diode  402  is maximized such that the phase angle is at its minimum (and lamps  30  are at their brightest). When potentiometer  408  is at its maximum resistance, the light output is at its dimmest. Thus, potentiometer  408  inherently functions as an adjustable dimmer control. Potentiometer  406  is disposed in series with ambient sensor  62  and resistor  413  in the lower leg of voltage divider  404 . Accordingly, potentiometer  406  may be employed to further adjust the instantaneous voltage presented to zener diode  402 . Thus, potentiometer  406  inherently represents a user-accessible high-end trim adjustment mechanism. Those of ordinary skill in the art will understand that the high end trim relates to the maximum amount of power that is delivered to the load. Thus, potentiometer  406  may be adjusted based on lighting requirements and energy consumption considerations. Potentiometer  410  is disposed in series with lamps  30  and therefore adjusts the amplitude of the AC current from the power source to the load. While potentiometer  410  inherently represents a high end adjustment of the lamp luminosity, it is less efficient (than potentiometer  406 ) from an energy savings standpoint because the increase in the resistance merely dissipates energy that otherwise would be employed by lamps  30  in heat (I 2 R thermal losses). 
     Device  10  may also include switch  412 . Switch  412  provides the device with ON/OFF functionality. When switch  412  is in the ON position, lamp  30  emission is controlled by the light sensor  62 . When switch  412  is turned OFF, lamps  30  are deenergized irrespective of ambient light conditions. Switch  412  may be coupled to a user accessible potentiometer. In an alternate embodiment of the present invention, circuit  900  may include ON/OFF switch  412  without including an ambient light detection function. 
     It will be apparent to those of ordinary skill in the pertinent art that modifications and variations can be made to the ambient light sensor  62  of the present invention. For example, a cadmium-sulfide photo-cell may be employed herein. Other types of light sensors are equally applicable to the invention such as photo-diodes or photo-transistors that generate an electrical current in response to the amount of ambient light. Since the light sensitivity of light sensors may vary from device to device during their manufacture, a factory adjustable trimming element such as resistor  413  may be included in the hallway light device to compensate for the variation. Further, potentiometer  406  also inherently functions as an adjustable trimming element by virtue of it being in series with resistor  413  and sensor  62 . 
     Referring to  FIG. 10 , a circuit schematic diagram in accordance with another embodiment of the present invention is shown.  FIG. 10  includes a circuit  1000  that features a false turn-off rejection circuit. The circumstances causing false turn-off were described above in the discussion of the proximity detector. Circuit  1000  includes processor  500  disposed between ambient light sensor  62  and control transistor  400 . Proximity sensor  501  is coupled to processor  500 . Proximity sensor  501  includes an infrared transmitter  502  and an infrared detector  505 . When an object passes device  10 , the infrared light emitted from infrared transmitter  502  is reflected to receiver  505 . Receiver provides processor  500  with a detection signal. Processor  500  responds by generating an “object present” signal that overrides the ambient light detector signal and turns transistor  400  ON. Accordingly, lamps  30  are energized when an object is deemed to be in the field of view of proximity sensor  501  irrespective of the ambient light level detected by ambient light sensor  62 . 
     In the discussion of  FIG. 7 , it was noted that the present invention can be implemented as a power control wiring device such as a light dimmer, motor control, or a fan speed control. The schematic shown in  FIG. 9  is inherently well suited for power control wiring device applications. In the light dimmer application mentioned above, the W 2  terminal can be connected to an outboard light source and W 2  would then function as a dimmed hot terminal regulating the amount of energy provided to the load. If the outboard lamp was significantly different than the lamps  30  (e.g., a 60 W tungsten lamp), the amount of current required to illuminate the lamp would be higher and would necessitate the use of a high gain transistor  400 . Of course, those of ordinary skill in the art would readily understand that modifications and variations such as resistor values, transistor gain, component selection, power handling capabilities and the like are well within the scope of the present invention. For example, replacing the combination of zener  402  and transistor  400  with a capacitively driven diac/triac combination is also within the powers of one of ordinary skill in the art because both combinations are means for efficiently utilizing the phase angle in the AC cycle; i.e., they energize the lighting load during a selected portion of the AC cycle. Of course, those of ordinary skill in the art would also be lead to consider a field effect transistor (FET) based circuit as well. 
     In another embodiment of the present invention, the false turn-off feature is implemented by a clock that is triggered by the ambient light detector  506  when it detects a step increase in light that is greater than a predetermined threshold. The step increase in light intensity may be caused by a light in the room being turned ON or by an object passing in front of the device  10 . Accordingly, processor  500  checks the state of the ambient light detector after a predetermined time delay, i.e., ten minutes, has elapsed. If the ambient light level exceeds the predetermined threshold after the time period has elapsed, processor  500  is programmed to determine that the step increase in light is due to a light in the room being turned ON. In response thereto, processor  500  turns lamps  30  OFF by providing an appropriate signal to the input of transistor  400  because it deems the additional light provided by device  10  to be unnecessary. On the other hand, if the ambient light level does not exceed the predetermined threshold level after the delay period elapses, processor  500  is programmed to determine that the step increase is from an object. Accordingly, processor  500  ensures that lamps  30  remain energized. 
     In another embodiment, processor  500  polls the ambient light detector during the predetermined time delay. If the detected ambient light levels are below the threshold, the time delay may be re-initialized or extended. This approach prevents multiple passes through the reflective region of the proximity detector from causing a false turn-off. 
       FIGS. 11A-D  provide timing diagrams illustrating the operation of an embodiment of the false turn-off circuitry.  FIG. 11A  represents the ON/OFF state of lamps  30 .  FIG. 11B  represents the control signal from processor  500  to transistor  400 .  FIG. 11C  represents the periodic delay signal  600  generated by processor  500 .  FIG. 11D  illustrates output signals from the ambient light detector  506  in response to a signal from ambient light sensor  62 . 
     In  FIG. 11A , lamps  30  are ON during interval  601  in response to a darkened ambient lighting condition. Lamps  30  are ON or OFF in response to a signal from control transistor  400  as illustrated in  FIG. 11B . The predetermined periodic time delay  600  is illustrated by  FIG. 11C . When periodic time delay  600  elapses, processor  500  turns transistor  400  OFF for a predetermined time interval  602 . Lamps  30  turn OFF for approximately the same time interval  602 . The absences of light during intervals  602  are too brief to be noticeable. In addition, processor  500  interrogates detector  506  however only during time intervals  602  when lamps  30  are not ON. 
       FIG. 11D  depicts occasions when a person or nearby object is close to the wiring device. Occasion  604  is not coincident with an interval  602 . Since ambient light detector  506  is not being interrogated during occasion  604 , lamps  30  remain ON. On the other hand, occasion  606  is coincident with an interval  602 . Even though ambient light detector  506  is being interrogated, lamps  30  are OFF when the interrogation is taking place. This avoids the possibility of any reflected light off of the person or object that would otherwise cause false-turn off. An occasion  608  when a light is turned ON in the room is also depicted. Of course, the light is detected by detector  506  during a subsequent interval  602 . In turn, processor  500  turns lamps  30  OFF at time  610 . Lamps  30  turn on again when a darkened ambient condition returns at time  612 . The darkened ambient condition is recognized by processor  500  during a subsequent interval  602 . In response, processor  500  turns lamps  30  ON at time  614 . 
     Stated generally, false turn-off of lamps  30  is avoided by periodically interrogating the status of the ambient light detector. Of course, the ambient light detector must be interrogated when lamps  30  are OFF, otherwise lamps  30  would never turn on. The interrogation rate when the lamps  30  are OFF is at the same periodic interrogation rate as when lamps  30  are ON. In another embodiment, the interrogation rate when lamps  30  are OFF is different in comparison to when lamps  30  are ON. The ambient light detector may even be continuously interrogated when lamps  30  are OFF. Advantageously, lamps  30  would then turn ON immediately in response to a darkened room ambient as opposed to having to wait for the next interrogation interval before turning ON. 
     As embodied herein and depicted in  FIG. 12 , a schematic of a lighting circuit  1200  in accordance with an alternate embodiment of the present invention is disclosed. Circuit  1200  includes an emergency lighting feature embodied by capacitor  700 . Capacitor  700  provides power to lamps  30  when there is a loss of source voltage. Circuit  1200  enables wiring device  10  to emit light into a darkened space even when device  10  experiences a loss of external power. Capacitor  700  may provide enough power to energize lamps  30  during a loss of source voltage for a period of at least about ten minutes. Of course, the embodiment of  FIG. 12  may also include the other features and benefits that have been previously described such as proximity sensing capability, ambient light sensing capability, and/or false turn-off rejection. Circuit  1200  may also be adapted to the embodiments depicted in  FIG. 7  and  FIG. 8 , i.e., include a wiring device in addition to the light emitting portion. 
     Referring to  FIG. 13 , an alternate embodiment of the emergency lighting circuit is disclosed. Circuit  1300  replaces the capacitor employed in  FIG. 12  with battery  702 . In both emergency lighting embodiments, the emergency lighting allows the ambient light sensor to operate in the event of a power loss. In other words, lamps  30  are energized when ambient light levels are relatively low, whether power is provided by some external source, or by way of capacitor  700  or battery  702 . 
     Referring to  FIG. 14 , a front view of a louvered cover plate  800  in accordance with an embodiment of the present invention is shown. The cover plate  800  is typically mounted to the hallway light device as the final installation step. Cover plate  800  includes a shrouding structure  802  which directs, concentrates or restricts the light emitted from lamps  30 . Plate  800  also includes a window  804  that accommodates the ambient light sensor. Plate  800  may also include a window for the proximity sensor as well and/or proximity sensor. Window  804  is also advantageous in that it prevents the extraneous light that contributes to false turn-off from reaching the ambient light sensor. Window  804  may be implemented as merely an aperture in plate  800  or it may be implemented as a lens disposed in an aperture. 
     In another embodiment of the present invention, the wall plate may include four lateral portions and an opening formed by the four lateral portions. As those skilled in the art will appreciate, the dimensions of a cover plate may conform to the cover plate depicted in the ANSI/NEMA WD6 standard such that the entire available surface area of cover lens  12  (See  FIG. 1  as an example) is disposed within the opening formed by the four lateral portions described above. Wall plate  800  ( FIG. 14 ) and the wall plate described herein in accordance with the ANSI/NEMA WD6 standard are interchangeable. 
     All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. 
     The use of the terms “a” and “an” and “the” and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms “comprising,” “having,” “including,” and “containing” are to be construed as open-ended terms (i.e., meaning “including, but not limited to,”) unless otherwise noted. The term “connected” is to be construed as partly or wholly contained within, attached to, or joined together, even if there is something intervening. 
     The recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. 
     All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., “such as”) provided herein, is intended merely to better illuminate embodiments of the invention and does not impose a limitation on the scope of the invention unless otherwise claimed. 
     No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. There is no intention to limit the invention to the specific form or forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention, as defined in the appended claims. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.