Patent Publication Number: US-10782010-B2

Title: Edge-lit lighting fixture sensor shield

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation-in-part of and claims priority to U.S. Nonprovisional patent application Ser. No. 16/588,665, filed Sep. 30, 2019, and titled “Edge-Lit Lighting Device,” which is a continuation of and claims priority to U.S. Nonprovisional patent application Ser. No. 15/901,625, filed Feb. 21, 2018, and titled “Edge-Lit Lighting Device,” which is a continuation of and claims priority to U.S. Nonprovisional patent application Ser. No. 15/186,122, filed Jun. 17, 2016, and titled “Edge-Lit Lighting Device,” which is a continuation application of and claims priority to U.S. Nonprovisional patent application Ser. No. 14/011,446, filed Aug. 27, 2013, and titled “Light Distribution Control of an Edge-Lit Lighting Device.” The entire contents of all of the foregoing applications are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to light distribution control, in particular to light distribution control of an edge-lit lighting device. 
     BACKGROUND 
     Edge-lit lighting fixtures include a light emitting panel (LEP) that emits light through a broad side of the LEP. For example, the lighting fixture may include a light source, such as a light emitting diode (LED), that is positioned close to a narrow side of the LEP. Light from the light source may enter the LEP through the narrow side of the LEP. The light from the light source that enters the LEP through the narrow side of the LEP may be emitted by the LEP through the broad side of the LEP to illuminate a space around the lighting fixture. A distribution pattern of the light emitted by the LEP of the lighting fixture may depend on, for example, the intensity of the light that is emitted by the light source and that enters the narrow side of the LEP. When the LEP has multiple narrow sides (i.e., the LEP is not round), the distribution pattern of the light emitted by the LEP may also depend on the particular narrow side of multiple narrow sides of the LEP through which the light from the light source enters the LEP. 
     In some cases, the distribution pattern of light emitted by a standard edge-lit lighting fixture may not be desirable for some applications and/or situations. For example, an edge-lit lighting fixture that emits light that equally illuminates all parts of an area around the lighting fixture may not be desirable. To illustrate, a series of lighting fixtures may be powered to provide lighting for a parking (deck) garage. However, it may be undesirable for the light to illuminate areas outside of the parking garage. To avoid illuminating some areas around the lighting fixtures, the lighting fixtures may need to include structures such as inserts and/or shields. Furthermore, the need for illumination of an area around the lighting fixture may change based on particular situations. For example, an area around the lighting fixture may need to be illuminated only when the area is occupied. 
     Accordingly, a lighting device that can be set and/or adjusted to emit light that has a particular distribution pattern may be desirable. 
     SUMMARY 
     In general, the present disclosure relates to light distribution control of an edge-lit lighting device. In an example embodiment, an edge-lit lighting device includes a light emitting panel (LEP), a first plurality of light sources, and a second plurality of LEDs. The first plurality of light sources are positioned proximal to a first narrow side of the LEP and are configured to emit a first light into the LEP through the first narrow side. The first light has a first intensity level. The second plurality of LEDs are positioned proximal to a second narrow side of the LEP and are configured to emit a second light into the LEP through the second narrow side. The second light has a second intensity level that is different from the first intensity level. The first intensity level and the second intensity level are set to achieve a particular distribution pattern of an output light emitted out through a broad side of the LEP. 
     In another example embodiment, an edge-lit lighting device includes a light emitting panel (LEP), a first plurality of light sources, and a second plurality of light sources. The first plurality of LEDs are positioned proximal to a first narrow side of the LEP and are configured to emit a first light into the LEP through the first narrow side. The first light has a first intensity level. The second plurality of LEDs are positioned proximal to a second narrow side of the LEP and are configured to emit a second light into the LEP through the second narrow side. The second light has a second intensity level. The LEP is configured to emit an output light through a broad side of the LEP. The first intensity level and the second intensity level of the second light are adjustable. The distribution pattern of the output light is changeable by adjusting one of the first intensity level and the second intensity level. 
     In another example embodiment, a method of controlling light distribution of an edge-lit lighting device includes installing an edge-lit lighting device that includes a light emitting panel (LEP), a first plurality of light sources positioned proximal to a first narrow side of the LEP and configured to emit a first light into the LEP through the first narrow side, and a second plurality of light sources positioned proximal to a second narrow side of the LEP and configured to emit a second light into the LEP through the second narrow side. The method further includes setting an intensity level of the first light and setting an intensity level of the second light. 
     In another example embodiment, an edge-lit lighting device includes a light emitting panel (LEP) having a broad side and a plurality narrow sides. The edge-lit lighting device further includes multiple light sources. Each of the multiple light sources is positioned proximal to a respective narrow side of the plurality of narrow sides and oriented to emit a respective light into the LEP through the respective narrow side of the plurality of narrow sides. A distribution of an output light emitted through the broad side of the LEP is changeable by powering on at least one light source of the multiple light sources that are powered off and by powering off one or more light sources of the multiple light sources that are powered on. 
     In another example embodiment, an edge-lit lighting fixture includes a light emitting panel (LEP) and a light emitting diode (LED) light source positioned proximal to a perimeter edge of the LEP and configured to emit a light into the LEP through the perimeter edge. At least a portion of the light is emitted through a broad surface of the LEP as an illumination light to illuminate an area. The edge-lit lighting fixture further includes a sensor positioned at the broad surface of the LEP to detect ambient light in the area, where the LED light source is powered on based on the sensor. The edge-lit lighting fixture also includes a sensor shield positioned around a portion of the sensor to block the illumination light from directly reaching the sensor. 
     In another example embodiment, an edge-lit lighting fixture includes a light emitting panel (LEP) and a light emitting diode (LED) light source positioned proximal to a perimeter edge of the LEP and configured to emit a light into the LEP through the perimeter edge. At least a portion of the light is emitted through a broad surface of the LEP as an illumination light to illuminate an area. The edge-lit lighting fixture further includes a sensor positioned at the broad surface of the LEP to detect ambient light in the area, where the LED light source is powered on based on the sensor. The edge-lit lighting fixture also includes a sensor shield positioned around a portion of the sensor to block the illumination light from directly reaching the sensor and a frame positioned adjacent the perimeter edge of the LEP. 
     These and other aspects, objects, features, and embodiments will be apparent from the following description and the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Reference will now be made to the accompanying figures, which are not necessarily to scale, and wherein: 
         FIGS. 1A and 1B  illustrates a lighting device including a light emitting panel (LEP) in accordance with an example embodiment; 
         FIG. 2A  illustrates the lighting device of  FIG. 1A  including a set of light emitting diodes (LEDs) that are powered on in accordance with an example embodiment; 
         FIG. 2B  illustrates an Iso-footcandle plot that corresponds to the lighting device of  FIG. 2A  in accordance with an example embodiment; 
         FIG. 3A  illustrates the lighting device of  FIG. 1A  including two sets of LEDs that are powered on in accordance with an example embodiment; 
         FIG. 3B  illustrates an Iso-footcandle plot that corresponds to the lighting device of  FIG. 3A  in accordance with an example embodiment; 
         FIG. 4A  illustrates the lighting device of  FIG. 1A  including two sets of LEDs that are powered on in accordance with another example embodiment; 
         FIG. 4B  illustrates an Iso-footcandle plot that corresponds to the lighting device of  FIG. 4A  in accordance with an example embodiment; 
         FIG. 5A  illustrates the lighting device of  FIG. 1A  including three sets of LEDs that are powered on in accordance with an example embodiment; 
         FIG. 5B  illustrates an Iso-footcandle plot that corresponds to the lighting device of  FIG. 5A  in accordance with an example embodiment; 
         FIG. 6A  illustrates the lighting device of  FIG. 1A  including four sets of LEDs that are powered on in accordance with an example embodiment; 
         FIG. 6B  illustrates an Iso-footcandle plot that corresponds to the lighting device of  FIG. 6A  in accordance with an example embodiment; 
         FIGS. 7A-7D  are Iso-footcandle plots illustrating effects of different intensity levels of light from different light sources on the light distribution pattern of a lighting device in accordance with an example embodiment; 
         FIG. 8  is a flowchart illustrating a method of controlling light distribution of the edge-lit lighting device of  FIG. 1A  in accordance with an example embodiment; 
         FIG. 9  illustrates the lighting device of  FIG. 1A  according to another example embodiment; 
         FIG. 10  illustrates the sensor shield attached to the sensor of the lighting device of  FIG. 9  according to an example embodiment; 
         FIG. 11  illustrates the sensor of the lighting device of  FIG. 9  according to an example embodiment; 
         FIGS. 12 and 13  illustrate different views of the sensor shield of the lighting device of  FIG. 9  according to an example embodiment; and 
         FIG. 14  illustrates the inside of the lighting device of  FIG. 9  according to an example embodiment. 
     
    
    
     The drawings illustrate only example embodiments and are therefore not to be considered limiting in scope. The elements and features shown in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the example embodiments. Additionally, certain dimensions or placements may be exaggerated to help visually convey such principles. In the figures, the same reference numerals used in multiple drawings designate like or corresponding but not necessarily identical elements. 
     DETAILED DESCRIPTION OF THE EXAMPLE EMBODIMENTS 
     In the following paragraphs, particular embodiments will be described in further detail by way of example with reference to the figures. In the description, well known components, methods, and/or processing techniques are omitted or briefly described. Furthermore, reference to various feature(s) of the embodiments is not to suggest that all embodiments must include the referenced feature(s). 
     Turning now to the drawings, example embodiments are described.  FIGS. 1A and 1B  illustrate a lighting device including a light emitting panel (LEP) in accordance with an example embodiment. The lighting device  100  may be set and/or adjusted to emit an output light that has a desired light distribution pattern. For example, the lighting device  100  may emit light such that a portion of an area around the lighting device  100  is relatively highly illuminated by the light while another portion of the area is dimly illuminated. 
     The lighting device  100  includes the LEP  102  and a frame  104 . In some example embodiments, the lighting device  100  may also include an optional sensor  105 . The LEP  102  may be made from an acrylic material, glass, or another suitable material, that allows light to enter through one or more narrow sides of the LEP  102  and to be emitted through one or more broad sides of the LEP  102 . The LEP  102  may have an octagonal shape as illustrated in  FIG. 1B . The LEP  102  includes a broad side  106  and eight narrow sides. The eight narrow sides may have substantially equal dimensions. Alternatively, each of the eight narrow sides may have one or more dimensions that are different respective one or more dimensions of some or all other narrow sides of the eight narrow sides. In some example embodiments, the LEP  102  may include grooves on the broad side  106 . The LEP  102  also includes a second broad side that is opposite the broad side  106 . The second broad side may be covered with a reflector that reflects light toward the broad side  106 . The second broad side may also include grooves. 
     The lighting device  100  includes four sets of light sources  116 ,  118 ,  120 ,  122 , which are referred to as four sets of light emitting diodes (LEDs)  116 ,  118 ,  120 ,  122 , hereinafter. However, the four sets of light sources  116 ,  118 ,  120 ,  122  may be light sources other than LEDs. Further, the terms LED and LEDs as used herein may refer to discrete LED or LEDs, one or more organic light-emitting diodes (OLEDs), an LED chip on board that includes one or more discrete LEDs, an array of discrete LEDs, or light source(s) other than LEDs. Further, each set of light sources  116 ,  118 ,  120 ,  122  may be a single light source. Continuing with  FIG. 1 , the four sets of LEDs  116 ,  118 ,  120 ,  122  are each positioned close to a corresponding narrow side  108 ,  110 ,  112 ,  114  of the LEP. To illustrate, a first set of LEDs  116  is positioned close to a first narrow side  108  of the LEP  102 . A second set of LEDs  118  is positioned close to a second narrow side  110  of the LEP  102 . A third set of LEDs  120  is positioned close to a third narrow side  112  of the LEP  102 . A fourth set of LEDs  122  is positioned close to a fourth narrow side  114  of the LEP  102 . In some example embodiments, the sets of LEDs  116 ,  118 ,  120 ,  122  are disposed on a respective printed circuit board (PCB). 
     As illustrated in  FIG. 1B , the first set of LEDs  116  is positioned opposite to the third set of LEDs  120 , and adjacent to the second set of LEDs  118  and to the fourth set of LEDs  122 . Similarly, the second set of LEDs  118  is positioned opposite to the fourth set of LEDs  122 , and adjacent to the first set of LEDs  116  and to the third set of LEDs  120 . 
     In some example embodiments, the first set of LEDs  116  are configured to emit light toward the first narrow side  108  of the LEP  102 . The second set of LEDs  118  are configured to emit light toward the second narrow side  110  of the LEP  102 . The third set of LEDs  120  are configured to emit light toward the third narrow side  112  of the LEP  102 . The fourth set of LEDs  122  are configured to emit light toward the fourth narrow side  114  of the LEP  102 . 
     The lighting device  100  may illuminate an area around the lighting device with a light emitted through the broad side  106  of the LEP  102 . The lighting device  100  may emit a light through the broad side  106  of the LEP  102  based on one or more lights from the four sets of LEDs  116 ,  118 ,  120 ,  122 . For example, if all four sets of LEDs  116 ,  118 ,  120 ,  122  are powered on, the light emitted by the lighting device  100  through the broad side  106  of the LEP  102  is based on the light from each of the four sets of LEDs  116 ,  118 ,  120 ,  122 . As another example, if only two of the four sets of LEDs are powered on, the light emitted by the lighting device  100  through the broad side  106  of the LEP  102  is based on the lights from the two sets of LEDs that are powered. As yet another example, if only one of the four sets of LEDs is powered on, the light emitted by the lighting device  100  through the broad side  106  of the LEP  102  is based only on the light from the particular set of LEDs that are powered on. 
     The distribution pattern of the light emitted through the broad side  106  of the LEP  102  may depend on the particular set of LEDs that are powered on or off. For example, the distribution pattern of the light emitted through the broad side  106  of the LEP  102  is different when only the first set of LEDs  116  and the second set of LEDs  118  are powered on as compared to when only the first set of LEDs  116  and the third set of LEDs  120  are powered on. As another example, the distribution pattern of the light emitted through the broad side  106  of the LEP  102  is different when only the first set of LEDs  116  and the second set of LEDs  118  are powered on as compared to when only the second set of LEDs  118  and the fourth set of LEDs  120  are powered on. 
     For a fixed orientation of the lighting device  100 , the distribution pattern of the light emitted through the broad side  106  of the LEP  102  is different when only the first set of LEDs  116  and the second set of LEDs  118  are powered on as compared to when only the second set of LEDs  118  and the third set of LEDs  120  are powered on. Similarly, for a fixed orientation of the lighting device  100 , the distribution pattern of the light emitted through the broad side  106  of the LEP  102  is different when only the first set of LEDs  116  and the third set of LEDs  120  are powered on as compared to when only the second set of LEDs  118  and the fourth set of LEDs  122  are powered on. Thus, the distribution pattern of the light emitted through the broad side  106  may be changed by powering on one or more of the sets of LEDs  116 ,  118 ,  120 ,  122  and powering of the remaining sets of LEDs  116 ,  118 ,  120 ,  122 . By changing the particular one or more of the sets of LEDs  116 ,  118 ,  120 ,  122  that are powered on, the distribution pattern of the light emitted through the broad side  106  can be changed. 
     Further, the distribution pattern of the light emitted through the broad side  106  of the LEP  102  may also depend on the intensity of light from each of the sets of LEDs  116 ,  118 ,  120 ,  122 . In some example embodiments, the intensity of light from each powered-on set of LEDs  116 ,  118 ,  120 ,  122  may be adjusted to various levels ranging between approximately zero intensity corresponding to no light being emitted (i.e., substantially equivalent to being powered off) and the maximum intensity of light that can be emitted by the particular set of LEDs  116 ,  118 ,  120 ,  122 . In some example embodiments, intensity level of light emitted by each one of the sets of LEDs  116 ,  118 ,  120 ,  122  may be set or adjusted to zero by powering off the particular set of LEDs. The intensity of light from each one of the sets of LEDs  116 ,  118 ,  120 ,  122  may also be preset to a desired level prior to being powered on. The distribution pattern of the light emitted through the broad side  106  of the LEP  102  may be different when one or more sets of LEDs  116 ,  118 ,  120 ,  122  are powered to emit light at a full (i.e., one hundred percent) intensity level instead of, for example, at a substantially less intensity level. For example, the first set of LEDs  116  and the second set of LEDs  118  may be dimmed to emit light at fifty percent of the respective full intensity level of each set of LEDs  116 ,  118 . The distribution pattern of the light emitted through the broad side  106  of the LEP  102  is different when the first set of LEDs  116  and the second set of LEDs  118  are dimmed to emit light at fifty percent of their respective full intensity level as compared to when the first set of LEDs  116  and the second set of LEDs  118  emit light at their respective full intensity level. 
     In some example embodiments, the full intensity level of lights emitted by the four sets of LEDs  116 ,  118 ,  120 ,  122  may be substantially the same. In alternative embodiments, the full intensity level of light emitted by some of the sets of LEDs  116 ,  118 ,  120 ,  122  may be different from the full intensity level of light from the other sets of LEDs  116 ,  118 ,  120 ,  122 . To illustrate, the full intensity level of lights from the first set of LEDs  116  and from the third set of LEDs  120  may be substantially different from the full intensity level of lights from the second set of LEDs  118  and from the fourth set of LEDs  122 . For example, the full intensity level of light from each of the first set of LEDs  116  and the third set of LEDs  120  may be approximately fifty percent of the full intensity level of light from each of the second set of LEDs  118  and the fourth set of LEDs  122 . As another example, the full intensity level of light from each of the first set of LEDs  116  and the third set of LEDs  120  may be approximately seventy five percent of the full intensity level of light from each of the second set of LEDs  118  and the fourth set of LEDs  122 . By having different intensity levels of light emitted by the sets of LEDs  116 ,  118 ,  120 ,  122 , a desired distribution pattern of the light emitted through the broad side  106  of the LEP  102  may be achieved. 
     In some example embodiments, each of the four sets of LEDs  116 ,  118 ,  120 ,  122  may emit light that has a full intensity level that is substantially different from the full intensity level of light emitted by all other sets of LEDs  116 ,  118 ,  120 ,  122 . Thus, the distribution pattern of the light emitted through the broad side  106  may be changed by adjusting intensity of light emitting by one or more of the sets of LEDs  116 ,  118 ,  120 ,  122 . 
     In some example embodiments, the intensity level of light that each set of LEDs  116 ,  118 ,  120 ,  122  emits may be fixed. For example, the lighting device  100  may be designed such that some of the sets of LEDs  116 ,  118 ,  120 ,  122  emit light approximately at a first fixed intensity level while the remaining sets of LEDs  116 ,  118 ,  120 ,  122  emit light approximately at a second fixed intensity level. To illustrate, one or more drivers may provide power to the sets of LEDs  116 ,  118 ,  120 ,  122  such that each of the sets of LEDs  116 ,  118 ,  120 ,  122  emits light that has an intensity level intended to achieve a desired light distribution pattern. 
     In some example embodiments, the intensity level of light from one or more of the set of LEDs  116 ,  118 ,  120 ,  122  may be set by a user, such as a consumer or a technician. To illustrate, a user may set the intensity level of light from each set of LEDs  116 ,  118 ,  120 ,  122  at time of installation to achieve a desired distribution pattern of the light emitted through the broad side of the LEP  102 . For example, a user may power on one or more of the sets of LEDs  116 ,  118 ,  120 ,  122  and power off the remaining sets of LEDs  116 ,  118 ,  120 ,  122  to achieve a light distribution pattern that reduces the level of illumination of a particular part of the area around the lighting device  100 . Further, to change the light distribution pattern, the user may adjust the intensity level of the one or more sets of LEDs that are powered on. As another example, a user may power on all four sets of LEDs  116 ,  118 ,  120 ,  122  and configure each set of LEDs to emit light that has a corresponding intensity level that results in a desired distribution pattern of the light emitted through the broad side of the LEP  102 . 
     In some situations, several of the lighting device  100  may be installed in a particular area. For example, multiple of the lighting device  100  may be installed in parking lot. In such scenarios, the light distribution in the parking lot may depend on distribution of light from a number of the lighting devices. Thus, overall distribution of light in the parking lot may be controlled by adjusting the distribution of light from one or more of the lighting device while considering the effect of light emitted by the other lighting devices on the overall distribution of light. 
     Further, the distribution of light emitted through the broad side of the LEP  102  of the lighting device  100  may be considered in terms of the National Electrical Manufacturers Association (NEMA) light distribution standard and may be classified based on its NEMA type. 
     In some example embodiments, one or more sets of LEDs  116 ,  118 ,  120 ,  122  may be adjustable by a user to emit light that has a desired intensity level. In such embodiments, alternatively or in addition to setting intensity levels at time of installation, a user may adjust the intensity level of light from each set of LEDs  116 ,  118 ,  120 ,  122  after installation of the lighting device  100 . To illustrate, after installation, a user may adjust the intensity level of light from each set of LEDs  116 ,  118 ,  120 ,  122  based on one or more factors, such as time of day and occupancy of the area around the lighting device  100 . For example, a user may prefer that a portion of the area around the lighting device  100  is highly illuminated at all times while another portion of the area is highly illuminated only during a certain period of time. To achieve light distribution pattern that matches the user&#39;s illumination preference at different time periods, the user may, for example, power off or dim the light from one or more of the sets of LEDs  116 ,  118 ,  120 ,  122  as needed. Similarly, the user may power on or increase intensity of light from the one or more of the sets of LEDs  116 ,  118 ,  120 ,  122  as needed. In some example embodiments, a timer may be used to control the on-off powering and/or dimming operations. 
     In some example embodiments, two or more of the sets of LEDs  116 ,  118 ,  120 ,  122  may be controlled as a group. For example, the first set of LEDs  116  and the third set of LEDs  120  may be controlled using a single control means such as a dimmer and/or a switch. Similarly, the second set of LEDs  118  and the fourth set of LEDs  122  may be controlled using a single control means such as a dimmer and/or a switch. Although particular sets of LEDs are described as being controlled as a group, in alternative embodiments, various combinations of the sets of LEDs may be controlled as a group. Further, as it should be apparent from the above description, each of the four sets of LEDs  116 ,  118 ,  120 ,  122  may be independently controlled by a corresponding dimmer and/or on-off switch (e.g., a dual in-line (DIP) switch). 
     In some example embodiments, a single on-off switch may be used to power on and off all of the sets of LEDs  116 ,  118 ,  120 ,  122  while a dedicated dimmer is used to control a corresponding one of the sets of LEDs  116 ,  118 ,  120 ,  122 . In general, different combinations of on-off switch and dimmer control arrangements may be implemented for different applications. 
     In some example embodiments, the sensor  105  may be coupled to a switch to control whether one or more of the sets of LEDs  116 ,  118 ,  120 ,  122  are turned on or off. For example, the sensor  105  may be a motion sensor  105  that senses motion (e.g., cars, pedestrians, etc.) and provides an indication signal to an on-off switch to control whether one or more of the sets of LEDs  116 ,  118 ,  120 ,  122  are powered on or off. Alternatively or in addition, the motion sensor  105  may also be coupled to a dimmer to control the intensity level of light emitted by one or more of the sets of LEDs  116 ,  118 ,  120 ,  122 . Although the sensor  105  is shown attached to the LEP  102  of the lighting device  100 , in alternative embodiments, the sensor  105  may be remotely located detached from the lighting device  100  or may be attached to another member of the lighting device  100 . 
     In some example embodiments, the sensor  105  may include a light sensor (in addition or alternatively to a motion sensor) that is configured to detect light and provide a corresponding indication signal to an on-off switch to control whether one or more of the sets of LEDs  116 ,  118 ,  120 ,  122  are powered on or off. For example, some of the sets of LEDs may be powered on in response to the light sensor detecting low light level. Alternatively or in addition to being coupled to an on-off switch, the light sensor may also be coupled to a dimmer to control the intensity level of light emitted by one or more of the sets of LEDs  116 ,  118 ,  120 ,  122 . 
     In some example embodiments, the frame  104  may hide the four sets of LEDs  116 ,  118 ,  120 , and  122  from view, for example, at viewing angles below the lighting device  100 . The frame  104  may also hide from view the outline of the perimeter of the LEP  104 . In some example embodiments, the frame  104  may be made from aluminum, and may have aesthetic feature. The frame  104  may also be part of a heat management structure of the lighting device  100 . Although the frame  104  has a substantially circular shape as shown in  FIG. 1A , in alternative embodiments, the frame  104  may have other shapes without departing from the scope of this description. 
     Although the LEP  102  is shown in  FIG. 1B  as having an octagonal shape, in some alternative embodiments, the LEP  102  may have other shapes, including a rectangular shape, a V-shape, and a circular shape, without departing from the scope of this description. In general, the LEP  102  may have a polygon and other non-polygon shape and is not limited to the example shapes identified in this description and may have fewer or more than eight narrow sides. Each side of the LEP  102  may also be a straight or a curved side. Further, in some alternative embodiments, the lighting device  100  may include fewer or more than four sets of LEDs that emit light toward correspondingly narrow sides of the LEP  102 . For example, the lighting device  100  may include one, two, three, five, or more sets of LEDs that are positioned proximal to a corresponding narrow side of the LEP  102  having an octagonal or another shape. 
     To illustrate, in some example embodiments, the LEP  120  may be a circular-shape LEP. For example, multiple LEDs may be positioned around the outer narrow perimeter of the circular-shape LEP, where each LED is controlled (i.e., powered on, power off, and/or adjusted for light intensity) individually. Alternatively several groups of LEDs may be positioned around the narrow outer perimeter of the circular-shape LEP, where each group of LEDs is controlled individually. By controlling individual LEDs or groups of LEDs, distribution of light emitted by the circular-shape LEP may be changed as desired. In an alternative embodiment, the circular-shape LEP may have a cut-out (e.g., a rectangular cut-out) through the broad sides of the circular-shape LEP and the LEDs may be positioned to emit light into the circular-shape LEP through the narrow side in the cut-out. 
     As another example, the LEP  102  may be a V-shaped LEP, and LEDs or other light sources that are controllable individually or in groups may be positioned, for example, in the valley of the V-shape. 
       FIG. 2A  illustrates the lighting device  100  of  FIG. 1A  including a set of LEDs that are powered on in accordance with an example embodiment.  FIG. 2B  illustrates an Iso-footcandle plot that corresponds to the lighting device of  FIG. 2A  with a single set of LEDs powered on in accordance with an example embodiment. As illustrated in  FIG. 2A , the first set of LEDs  116  are powered on while the other sets of LEDs  118 ,  120 ,  122  shown in  FIG. 1B  are powered off. 
     Each curve of the Iso-footcandle plot shown in  FIG. 2B  (as well as  FIGS. 3B, 4B, 5B, 6B, and 7A-7D ) represents locations on a viewing plane below the lighting device  100  that experience substantially the same light intensity level. The center  202  of the Iso-footcandle plot represents a position in the viewing plane that is directly below the lighting device  100 . Thus, points on the plot that are farthest from the center  202  represent positions in the viewing plane that are farthest from the lighting device  100 . Positions in the viewing plane that are represented by a particular curve experience a light intensity level that is approximately fifty percent of the light intensity level experienced by positions represented by an immediately adjacent inner curve. 
     As can be seen in  FIG. 2B , when the first set of LEDs  116  are powered on and the other sets of LEDs  118 ,  120 ,  122  are powered off, some locations in the viewing plane that are at substantially equal distances from the lighting device  100  may experience different levels of light intensity. To illustrate, some positions on the right side of the lighting device  100  but that are farther away than closer positions on the left side of the lighting device  100  may experience relatively higher levels of light intensity than the closer positions that are on the left side of the lighting device  100 . For example, the farthest right position  204  on the outer most curve  202  experiences the same level of light intensity as the farthest left position  206  on the curve even though the farthest right position  206  is approximately twice as far from the center  202  of lighting device  100  as the farthest left position. 
     Accordingly, the lighting device  100  may be set to have only the first set of LEDs  116  powered on when a desired light distribution pattern corresponds to the pattern illustrated in  FIG. 2B . 
       FIG. 3A  illustrates the lighting device of  FIG. 1A  including two sets of LEDs that are powered on in accordance with an example embodiment.  FIG. 3B  illustrates an Iso-footcandle plot that corresponds to the lighting device of  FIG. 3A  in accordance with an example embodiment. 
     As illustrated in  FIG. 3A , the first set of LEDs  116  and the third set of LEDs  120  are powered on and the other sets of LEDs  118 ,  122  are powered off. As can be seen in  FIG. 3B , some locations in the viewing plane that are at substantially equal distances from the lighting device  100  may experience different levels of light intensity while other locations in the viewing plane that are at equal distance from the lighting device  100  may experience substantially the same level of light intensity. Further, locations in the viewing plane that are at different distances from the lighting device  100  may experience substantially the same level of light intensity. To illustrate, the farthest right position  304  on the outer most curve  312  and the farthest left position  306  on the outer most curve  312 , which are substantially at equal distance from the lighting device  100 , experience substantially the same level of light intensity. Similarly, the farthest back position  308  and the farthest front position  310  on the outermost curve  312 , which are at substantially equal distance from the lighting device  100 , experience substantially the same level of light intensity. However, the farthest right position  304  and the farthest left position  306  experience substantially the same level of light intensity as the farthest back position  308  and the farthest front position  310  even though the farthest right position  304  and the farthest left position  306  are significantly farther away from the lighting device  100  than the farthest back position  308  and the farthest front position  310 . 
     Accordingly, the lighting device  100  may be set to have the first set of LEDs  116  and the third set of LEDs  120  powered on and the other sets of LEDs  118 ,  122  powered off when a desired light distribution pattern of the lighting device  100  corresponds to the pattern illustrated in  FIG. 3B . 
       FIG. 4A  illustrates the lighting device of  FIG. 1A  including two sets of LEDs that are powered on in accordance with another example embodiment.  FIG. 4B  illustrates an Iso-footcandle plot that corresponds to the lighting device of  FIG. 4A  in accordance with an example embodiment. 
     As illustrated in  FIG. 4A , the first set of LEDs  116  and the second set of LEDs  118  are powered on and the other sets of LEDs  120 ,  122  are powered off. As can be seen in  FIG. 4B , some locations in the viewing plane that are at substantially equal distances from the lighting device  100  may experience different levels of light intensity while other locations in the viewing plane that are equal distance from the lighting device  100  may experience substantially the same level of light intensity. Further, locations in the viewing plane that are at different distances from the lighting device  100  may experience substantially the same level of light intensity. To illustrate, the farthest right position  404  on the outer most curve  412  and the farthest left position  406  on the outer most curve  412 , which are at substantially different distances from the lighting device  100 , experience substantially the same level of light intensity. Similarly, the farthest back position  408  and the farthest front position  410  on the outermost curve  412 , which are substantially at substantially different distances from the lighting device  100 , experience substantially the same level of light intensity. However, the farthest right position  404  and the farthest front position  410 , which are at substantially equal distance from the lighting device  100 , experience substantially the same level of light intensity. 
     Accordingly, the lighting device  100  may be set to have the first set of LEDs  116  and the second set of LEDs  118  powered on and the other sets of LEDs  120 ,  122  powered off when a desired light distribution pattern of the lighting device  100  corresponds to the pattern illustrated in  FIG. 4B . Even though only two of the sets of LEDs are powered on in both  FIGS. 3A and 4A , the light distribution patterns that correspond to  FIGS. 3A and 4A  are significantly different from each other as can be clearly seen by comparing the corresponding Iso-footcandle plots shown in  FIGS. 3B and 4B . 
       FIG. 5A  illustrates the lighting device of  FIG. 1A  including three sets of LEDs that are powered on in accordance with an example embodiment.  FIG. 5B  illustrates an Iso-footcandle plot that corresponds to the lighting device of  FIG. 5A  in accordance with an example embodiment. 
     As illustrated in  FIG. 5A , the first set of LEDs  116 , the second set of LEDs  118 , and the fourth set of LEDs  120  are powered on and the third set of LEDs  120  are powered off. As can be seen in  FIG. 5B , some locations in the viewing plane that are at different distances from the lighting device  100  may experience substantially the same level of light intensity. To illustrate, the farthest right position  504 , the farthest back position  508  on the same curve, and the farthest front position  510 , which are all on the same curve  512  and significantly farther from the lighting device  100  than the farthest left position  506 , experience substantially the same level of light intensity as the farthest left position  506 . Further, the farthest right position  504 , the farthest back position  508 , and the farthest front position  510 , which all are at approximately equal distances from the lighting device  100 , experience substantially the same level of light intensity. An overall comparison of the Iso-footcandle plots of  FIGS. 3B, 4B, and 5B  shows, the distribution pattern of the light represented by the Iso-footcandle plot of  FIG. 5B  is different from the light distribution patterns represented by the Iso-footcandle plots of  FIGS. 3B and 4B . 
     Accordingly, as illustrated in  FIG. 5A , the lighting device  100  may be set to have the first set of LEDs  116 , the second set of LEDs  118 , and the fourth set of LEDs  120  powered on and the third set of LEDs  120  powered off when a desired light distribution pattern of the lighting device  100  corresponds to the pattern illustrated in  FIG. 5B . 
       FIG. 6A  illustrates the lighting device of  FIG. 1A  including four sets of LEDs that are powered on in accordance with an example embodiment.  FIG. 6B  illustrates an Iso-footcandle plot that corresponds to the lighting device of  FIG. 6A  in accordance with an example embodiment. As illustrated in  FIG. 6A , all four sets of LEDs  116 ,  118 ,  120 ,  122  are powered on. As can be seen in  FIG. 6B , unlike the light distribution pattern illustrated in  FIGS. 3B, 4B, and 5B , all locations in the viewing plane that are substantially equally distanced from the lighting device  100  experience substantially the same level of light intensity. In addition, the overall distribution pattern of the light represented by the Iso-footcandle plot of  FIG. 6B  is different from the light distribution patterns represented by the Iso-footcandle plots of  FIGS. 3B, 4B, and 5B . 
       FIGS. 7A-7D  are Iso-footcandle plots illustrating effects of different intensity levels of lights from different light sources on the light distribution pattern of a lighting device in accordance with an example embodiment. For illustrative purposes, the inner curve in each of the Iso-footcandle plots of  FIGS. 7A-7D  may be a 0.2 foot-candle (fc) curve, and the outer curve may be a 0.1 fc curve. 
     In an example embodiment, the Iso-footcandle plot on  FIG. 7A  corresponds to the lighting device  100  illustrated in  FIG. 6A , where all four sets of LEDs  116 ,  118 ,  120 ,  122  are powered on. For example, the Iso-footcandle plot on  FIG. 7A  may correspond to all four sets of LEDs  116 ,  118 ,  120 ,  122  emitting light that are each substantially at a full intensity level. In some example embodiments, the Iso-footcandle plot on  FIG. 7B  may correspond to the lighting device  100  illustrated in  FIG. 6A , where the first set of LEDs  116  and the third set of LEDs  120  emit light at substantially full intensity level, and where the second set of LEDs  118  and the fourth set of LEDs  122  emit light at substantially fifty percent of the full intensity level. In some example embodiments, the Iso-footcandle plot on  FIG. 7C  may correspond to the lighting device  100  illustrated in  FIG. 6A , where the first set of LEDs  116  and the third set of LEDs  120  emit light at substantially full intensity level, and where the second set of LEDs  118  and the fourth set of LEDs  122  emit light at substantially twenty five percent of the full intensity level. In some example embodiments, the Iso-footcandle plot on  FIG. 7D  may correspond to the lighting device  100  illustrated in  FIG. 3A , where the first set of LEDs  116  and the third set of LEDs  120  emit light at a substantially full intensity level, and where the second set of LEDs  118  and the fourth set of LEDs  122  are powered off (alternatively, dimmed to substantially zero percent of the full intensity level). 
     As comparison of the Iso-footcandle plots of  FIGS. 7A-7D  illustrates, changes in the intensity level of light emitted by two of the sets of LEDs  116 ,  118 ,  120 ,  122  affects the light distribution pattern of the lighting device  100 . Accordingly, the lighting device  100  may be configured to emit light that has a particular light distribution pattern by setting or adjusting one or more of the sets of LEDs  116 ,  118 ,  120 ,  122  to emit a light that has a particular level of intensity. 
     Although  FIGS. 7A-7D  are described with respect to four sets of LEDs where intensity level of light from two of the four sets of LEDs are set or adjusted, in alternative embodiments, only one or more than two of the four sets may be set and/or adjusted to emit light so that each have particular levels of intensity to produce a particular distribution pattern of the light from the lighting device  100 . Further, as described above, in some alternative embodiments, the lighting device  100  may have fewer or more than four sets of LEDs. In addition, although particular levels of light intensity are described, the intensity of light from each set of LEDs may be adjusted to have a level ranging between a full intensity level and substantially being powered off. Further, as described above, in some example embodiments, the level of light intensity of light from each set of LEDs may be independently controlled. 
       FIG. 8  is a flowchart illustrating a method of controlling light distribution pattern of an edge-lit lighting device in accordance with an example embodiment. The method  800  includes installing an edge-lit lighting device, at step  802 . For example, a technician may install the edge-lit lighting device, such as the edge-lit lighting device  100  of  FIG. 1A . To illustrate, the edge-lit lighting device may include a light emitting panel (LEP), a first plurality of light emitting diodes (LEDs) positioned proximal to a first narrow side of the LEP and configured to emit a first light toward the first narrow side, and a second plurality of LEDs positioned proximal to a second narrow side of the LEP and configured to emit a second light toward the second narrow side. For example, the first plurality of LEDs may correspond to the first set of LEDs  116  of  FIG. 1B . Similarly, the second plurality of LEDs may correspond to, for example, the second set of LEDs  118  or the third set of LEDs  120  of  FIG. 1B . 
     The method  800  further includes setting an intensity level of the first light, at step  804 . For example, the first plurality of LEDs may be set to emit light at a full intensity level. The method  800  also includes setting an intensity level of the second light, at step  806 . For example, the second plurality of LEDs may be set to emit light at a full intensity level as well. Alternatively, the second plurality of LEDs may be set to emit light at approximately fifty percent of the full intensity level. 
     In some example embodiments, the method  800  also includes adjusting the intensity level of the first light, at step  808 . For example, adjusting the intensity level of the first light may include dimming the first light. Alternatively or in addition, the method  800  may also include adjusting the intensity level of the second light. 
       FIG. 9  illustrates the lighting device  100  of  FIG. 1A  according to another example embodiment. Referring to  FIGS. 1A-9 , in some example embodiments, the lighting device (e.g., a lighting fixture)  100  includes the LEP  102 , the frame  104 , and the sensor  105 . As described above, the sensor  105  may include a light sensor and a motion sensor. The lighting device  100  may also include a back cover  906  that may be attached to the frame  104  at a back side of the lighting device  102 . 
     In some example embodiments, the lighting device  100  may include a sensor shield  902  that is positioned to shield the sensor  105  from at least a portion of the light emitted by the lighting device  100  through the broad side  106  of the LEP  102  (i.e. illumination light). For example, a portion of the sensor  105  may be positioned in a cavity  904  of the sensor shield  902 . To illustrate, a portion of the sensor shield  902  may be positioned around a portion of the sensor  105  to prevent some of the light emitted from the LEP  102  from directly reaching the sensor  105 . The sensor shield  902  may be positioned such that the sensor  105  can detect ambient light while interference by the light emitted from the LEP  102  is reduced by the sensor shield  902 . 
     In some example embodiments, the sensor shield  904  may also be positioned around the sensor  105  such that the desired motion sensing range of the sensor  105  is not impaired or excessively impaired by the sensor shield  904 . For example, one or both of the distance range and the angular range of the sensor  105  for sensing motion may be within desired ranges or may not be excessively less than desired ranges. 
     By reducing the amount of light from the lighting device  100  that directly reaches the sensor  105 , the sensor shield  902  can enable the sensor  105  to more effectively sense ambient light. Reducing the interference of the light from the lighting device  100  in the detection of ambient light enables the lighting device  100  to more effectively control the light provided by the lighting device  100 . By reducing the amount of light from the lighting device  100  that directly reaches the sensor  105  with no or limited interference in the motion sensing and ambient light sensing, the sensor shield  902  can enable the lighting device  100  to more effectively control its operations. 
     In some alternative embodiments, the sensor shield  902  and/or the sensor  105  each may have a different shape than shown without departing from the scope of this disclosure. In some alternative embodiments, the LEP  102  and/or the frame  104  may each have a different shape than shown without departing from the scope of this disclosure. In some alternative embodiments, the sensor  105  may not include motion sensor without departing from the scope of this disclosure. 
       FIG. 10  illustrates the sensor shield  902  attached to the sensor  105  of the lighting device  100  of  FIG. 9  according to an example embodiment. Referring to  FIGS. 1A-10 , in some example embodiments, the sensor  105  may include a sensor body  1002 , a sensor lens  1004 , and shaft section  1006  extending between the sensor body  1002  and the sensor lens  1004 . The sensor  105  may detect motion and light through the lens  1004 . The shaft section  1006  may extend through the attachment nut  1008  such that the attachment nut  1008  is rotated around the shaft section  1006  to move the attachment nut  1008  upward toward the LEP  102  to firmly attach the sensor  105  to the LEP  102 . 
     In some example embodiments, the sensor shield  902  may include a skirt portion  1010  and a back portion  1012 . The shaft section  1006  may extend through an opening in the back portion  1012 . The sensor  105  may be assembled by attaching the shaft section  1006  to the sensor lens  1004  and/or to the sensor body  1002  after the shaft section  1006  is extended through the opening of the back portion  1012  of the sensor shield  902 . The back portion  1012  of the sensor shield  902  may rest on or may otherwise be positioned at the back side of the lens  1004  of the sensor  105 . The skirt section  1010  of the sensor shield  902  may extend down from the back portion  1012  of the sensor shield  902  such that the skirt portion  1010  extends circumferentially around the lens  1004  of the sensor  105 . For example, the skirt portion  1010  may extend around the sensor lens  1004  such that the skirt portion  1010  prevents the light from the LEP  102  from directly reaching the sensor lens  1004 . 
     In some example embodiments, the skirt portion  1010  may have an outer perimeter edge  1014 , and the skirt section  1010  may extend down such that a bottom end portion of the sensor lens  1004  is slightly below the outer perimeter edge  1014  of the skirt portion  1010 . To illustrate, the bottom end portion of the sensor lens  1004  may be outside the cavity  904  of the sensor shield  902 . For example, the bottom end portion of the sensor lens  1004  may be a portion of the sensor lens  1004  that is used in sensing ambient light. Although the bottom end portion of the sensor lens  1004  is below the outer perimeter edge  1014  (i.e., outside the cavity  904 ), the skirt portion  1010  may still prevent the light from the LEP  102  from directly reaching the sensor lens  1004 . Because the bottom end portion of the sensor lens  1004  is below the outer perimeter edge  1014 , the sensor shield  902  may allow the sensor  105  to provide a desired level of ambient light sensing while preventing direct light from the LEP  102  from reaching the sensor  105 . 
     In some example embodiments, a portion of the sensor lens  1004  that is used in motion sensing by the sensor  105  may be fully inside the cavity  904  of the sensor shield  902 . For example, the skirt portion  1010  may extend circumferentially around the motion sensing portion of the sensor lens  1004 . The sensor  105  may have a motion sensing viewing angle that follows the motion sensing viewing line  1016  around the outer perimeter edge  1014  of the skirt portion  1010 . To illustrate, the motion sensing viewing line  1016  may depend on the height of the skirt portion  1010  between the outer perimeter edge  1014  and the back portion  1012  of the skirt portion  1010 . That is, the motion sensing viewing line  1016  may depend on how much the skirt portion  1010  extends below the vertical level  1018  of the motion sensing portion of the sensor lens  1004 . Although the motion sensing range of the sensor  105  may be reduced by the sensor shield  902  in contrast to embodiments of the lighting device  100  that do not include the sensor shield  902 , the sensor shield  902  may still allow the sensor  105  to have a desired motion sensing range. 
     In some alternative embodiments, the skirt portion  1010  may extend down to a level that is higher or level than shown in  FIG. 10  without departing from the scope of this disclosure. In some alternative embodiments, the different components of the sensor  105  may have different shapes than shown without departing from the scope of this disclosure. In some example embodiments, one or more components of the sensor  105  may be integrated into a single component without departing from the scope of this disclosure. 
       FIG. 11  illustrates the sensor of the lighting device of  FIG. 9  according to an example embodiment. Referring to  FIGS. 1A-11 , in some example embodiments, the sensor lens  1004  may include a light sensing portion  1102  and a motion sensing section  1104 . As described above with respect to  FIG. 10 , the light sensing portion  1102  may extend slightly below the skirt portion  1010  of the sensor shield  902 , while the motion sensing section  1104  may be above the outer perimeter edge  1014  of the skirt portion  1010 . In some alternative embodiments, both the light sensing portion  1102  and the motion sensing section  1104  may be below or above the outer perimeter edge  1014  of the skirt portion  1010 . 
     In some alternative embodiments, the motion sensing portion  1104  may extend slightly below the skirt portion  1010  of the sensor shield  902 , while the light sensing section  1102  may be above the outer perimeter edge  1014  of the skirt portion  1010 . In some alternative embodiments, the lighting device  100  may include a different type of sensor without departing from the scope of this disclosure. 
       FIGS. 12 and 13  illustrate different views of the sensor shield of the lighting device of  FIG. 9  according to an example embodiment. Referring to  FIGS. 1A-13 , in some example embodiments, the sensor shield  902  may include the skirt portion  1010  and the back portion  1012 , where the back portion  1012  has an opening  1202  formed therethrough. The sensor shield  902  may be attached to the sensor  105  by extending the shaft section  1006  of the sensor  105  through the opening  1202 . For example, the back cover  1012  may be position on the lens  1004  after the shaft section  1006  is extended through the opening  1202  such that the lens  1004  is positioned at least partially in the cavity  904  of the sensor shield  902 . 
     In some example embodiments, the cylindrical shape of the skirt portion  1010  may provide a  360  degree blockage of direct light from the LEP  102  from reaching the sensor lens  1004 . Because light is detected by the sensor  105  through the sensor  1004 , the blockage of direct light from the LEP  102  may allow sensor  105  to more effectively detect ambient light near the lighting device  100 . The sensor shield  902  may be made from an optically opaque material to effectively block light. For example, the sensor shield may be made from a plastic material or a metallic material (e.g., aluminum) using methods, such as bending, cutting, etc., as can be readily contemplated by those of ordinary skill in the art with the benefit of this disclosure. 
       FIG. 14  illustrates the inside of the lighting device of  FIG. 9  according to an example embodiment. Referring to  FIGS. 1A-14 , in some example embodiments, the lighting device  100  includes electrical wires  1402  that are used to provide power to the lighting device  100 . For example, at least some of the electrical wires  1402  may be routed to a driver  1404  that provides power to the light sources  1408  and other light sources of the lighting device  100 . The driver  1404  may be positioned in a cavity of the back cover  906  For example, the light sources  1408  may correspond to the light sources  116 ,  118 ,  120 , or  122 . As shown in  FIG. 14 , the light sources  1408  may be positioned against a gasket  1408  to emit light into the LEP  102  through a narrow side of the LEP  102 . As the light exits the LEP  102  through the broad side  106  of the LEP  102 , the sensor shield  902  blocks the light from directly reaching the sensor  105 . Because the sensor shield  902  is open at its bottom end, the sensor  105  has large motion and light sensing ranges with respect to distance and angle with reduced interference from the light emitted through the broad side  106  of the LEP  102 . 
     Although particular embodiments have been described herein in detail, the descriptions are by way of example. The features of the embodiments described herein are representative and, in alternative embodiments, certain features, elements, and/or steps may be added or omitted. Additionally, modifications to aspects of the embodiments described herein may be made by those skilled in the art without departing from the scope of the following claims, the scope of which are to be accorded the broadest interpretation so as to encompass modifications and equivalent structures.