Lighting assembly with adjustable light output

A lighting assembly includes a light guide and light source. The light guide includes light input regions, at least one of the light input regions associated with an optical modifying characteristic, and the light guide is configured to propagate light by total internal reflection. The light source is located adjacent the light input regions. The light source and light input regions are variably positionable relative to one another to vary a location at which light is incident on the light input regions such that light emitted from the light source is selectively apportioned between the light input regions. A characteristic of the light output from the lighting assembly is modified based on the optical modifying characteristic of the at least one of the light input regions and the relative positioning of the light source and the light input regions.

BACKGROUND

Energy efficiency has become an area of interest for energy consuming devices. One class of energy consuming devices is lighting devices. Light emitting diodes (LEDs) show promise as energy efficient light sources for lighting devices. But control over color and light output distribution is an issue for lighting devices that use LEDs or similar light sources.

DESCRIPTION

Embodiments will now be described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. The figures are not necessarily to scale. Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

Aspects of this disclosure relate to a lighting assembly. As illustrated inFIG. 1, one type of lighting assembly100is a light bulb200. As illustrated inFIG. 2, another type of lighting assembly100is a lighting fixture300. The lighting assembly100, whether a light bulb200(e.g., as shown inFIG. 1), a lighting fixture300(e.g., as shown inFIG. 2), or another type of lighting device, is described in greater detail herein with reference to the various embodiments illustrated in the figures.

The lighting assembly includes a light guide and a light source. The light guide includes light input regions, at least one of the light input regions associated with an optical modifying characteristic, and the light guide is configured to propagate light by total internal reflection. The light source is located adjacent the light input regions and the light source and light input regions are variably positionable relative to one another to vary the location at which light is incident on the light input regions. Light emitted from the light source is selectively apportioned between the light input regions so that a characteristic of the light output from the lighting assembly is modified based on the optical modifying characteristic of the at least one of the light input regions and the relative positioning of the light source and the light input regions.

In the case of the light bulb, the light bulb additionally includes a base configured to mechanically mount the light bulb and receive electrical power.

With additional reference toFIGS. 3-6, the lighting assembly100includes a light guide102, which is a solid article made from, for example, acrylic, polycarbonate, glass, or other appropriate material. The light guide102may be rigid or flexible. The light guide102may also be a multi-layer light guide having two or more layers. The light guide102includes a first major surface106and a second major surface108opposite the first major surface106. The light guide102is configured to propagate light by total internal reflection (TIR) between the first major surface106and the second major surface108.

The light guide102includes light extracting elements (not shown) in or on at least one of the major surfaces106,108. Light extracting elements that are in or on a major surface106,108will be referred to as being “at” the major surface. Each light extracting element functions to disrupt the total internal reflection of the propagating light that is incident on the light extracting element. In one embodiment, the light extracting elements reflect light toward the opposing major surface so that the light exits the light guide102through the opposing major surface. Alternatively, the light extracting elements transmit light through the light extracting elements and out of the major surface of the light guide102having the light extracting elements. In another embodiment, both of these types of light extracting elements are present. In yet another embodiment, the light extracting elements reflect some of the light and refract the remainder of the light incident thereon. Therefore, the light extracting elements are configured to extract light from one or both of the major surfaces106,108.

Light guides having such light extracting elements are typically formed by a process such as stamping, molding, embossing, extruding, laser etching, chemical etching, or another suitable process. Light extracting elements may also be produced by depositing elements of curable material on the light guide102and curing the deposited material using heat, UV-light or other radiation. The curable material can be deposited by a process such as printing, ink jet printing, screen printing, or another suitable process.

Exemplary light extracting elements include light-scattering elements, which are typically features of indistinct shape or surface texture, such as printed features, ink-jet printed features, selectively-deposited features, chemically etched features, laser etched features, and so forth. Other exemplary light extracting elements include features of well-defined shape, such as V-grooves, lenticular grooves, and features of well-defined shape that are small relative to the linear dimensions of the major surfaces106,108, which are sometimes referred to as micro-optical elements. The smaller of the length and width of a micro-optical element is less than one-tenth of the longer of the length and width of the light guide102and the larger of the length and width of the micro-optical element is less than one-half of the smaller of the length and width of the light guide. The length and width of the micro-optical element is measured in a plane parallel to the major surface106,108of the light guide102for flat light guides or along a surface contour for non-flat light guides102.

Micro-optical elements are shaped to predictably reflect or refract light. However, one or more of the surfaces of the micro-optical elements may be modified, such as roughened, to produce a secondary effect on light output. Exemplary micro-optical elements are described in U.S. Pat. No. 6,752,505 and, for the sake of brevity, are not described in detail in this disclosure. The micro-optical elements may vary in one or more of size, shape, depth or height, density, orientation, slope angle or index of refraction such that a desired light output from the light guide is achieved.

The light guide102has at least one external edge, the total number of external edges depending on the configuration of the light guide102. An external edge is an edge that is not completely surrounded by the light guide102. In the case where the light guide102is rectangular (e.g., as shown inFIG. 4), the light guide102has four external edges110,112,114,116(e.g., side edges110,112, end edge116, and light input edge114). In other embodiments, the light guide has a different shape, and the total number of external edges is different. For example, where the light guide102is a hollow cylinder (e.g., as shown inFIG. 1), is frustroconical, is a frustrated pyramid, is a dome with a hole cut at the dome's apex, or another similar shape, the light guide has two opposing external edges114,116. In an embodiment where the light guide102is shaped like a dome or has a shape approximating the bulbous shape of a conventional incandescent bulb, the light guide102has a single external edge. Other geometries for the light guide102result in a corresponding number of external edges. Depending on the geometry of the light guide102, each external edge may follow a straight path or a curved path, and adjacent edges may meet at a vertex or join in a curve.

In some embodiments, the light guide102includes an internal edge (not shown), which is an edge completely surrounded by the light guide102. The internal edge is usually the edge of a hole that extends between the major surfaces of the light guide102.

The length and width dimensions of each of the major surfaces106,108are much greater, typically ten or more times greater, than the thickness of the light guide102. The thickness is the dimension of the light guide102in a direction orthogonal to the major surfaces106,108. In the rectangular embodiment, the length (measured from external edge114to external edge116) and the width (measured from external edge110to external edge112) of each of the major surfaces are both much greater than the thickness of the light guide102. The thickness of the light guide102may be, for example, about 0.1 millimeters (mm) to about 10 mm.

At least one of the edges, whether an external edge or internal edge, serves as a light input edge. Light emitted from one or more light sources104is directed toward the light input edge. In the embodiment shown inFIGS. 3-6, external edge114serves as the light input edge.

The light input edge114includes light input regions. The light input regions are associated with different optical modifying characteristics. An optical modifying characteristic is indicated by an effect that the light input region has on light that is incident thereon. For purposes of this description, a light input region that lacks an optical modifying characteristic will be considered specularly transmissive, even though specularly transmissive material refracts light that passes through the material at a non-zero angle of incidence. Exemplary optical modifying characteristics and the effect that the light input regions have on light incident thereon are discussed in more detail below with reference to the illustrated embodiments.

The light input edge includes any appropriate number of light input regions. Furthermore, any appropriate number of light input regions may be associated with a given light source. In the illustrated embodiments, the change in optical modifying characteristic from one light input region to another light input region is abrupt. In other embodiments, the transition between the light input regions may be gradual.

FIGS. 3-6illustrate an embodiment where light source104is associated with input regions117,118. In the illustrated embodiment, the optical modifying characteristic of one of the light input regions modifies the light ray angle distribution of the light incident thereon. In an example, light input region117includes optical elements, an exemplary one of which is shown at119. The reference numeral119will additionally be used to refer to the optical elements collectively. The optical elements119modify the light ray angle distribution of the light incident thereon. In this disclosure, the term light ray angle distribution is used to describe the variation of the intensity of light with ray angle (typically a solid angle) over a defined range of ray angles. In an example in which the light is input to an edge-lit light guide, the defined range of ray angles is from −90° to +90° relative to the normal to the light input region117in a direction away from the light source104.

The optical elements119of the light input region117are illustrated as lenticular grooves oriented orthogonally to major surfaces106,108. In other embodiments, the optical elements119have other suitable orientations and shapes, for example, lenticular grooves oriented parallel to major surfaces106,108, V-grooves oriented orthogonally to major surfaces106,108, V-grooves oriented parallel to major surfaces106,108, lenses, or combinations thereof. Other exemplary optical elements include light-scattering elements, which are typically features of indistinct shape or surface texture, such as printed features, ink jet printed features, selectively-deposited features, chemically etched features, laser etched features, and so forth. Other exemplary optical elements include features of well-defined shape, such as V-grooves, lenticular grooves, and features of well-defined shape that are small relative to the linear dimensions of the light input edge114, which are sometimes referred to as micro-optical elements for the light input region. The smaller of the length and width of a micro-optical element is less than one-half of the longer of the length and width of the light input edge114, and the larger of the length and width of the micro-optical element is less than the smaller of the length and width of the light input edge114. The length and width of the micro-optical element for the light input region is measured in the plane that is parallel to and includes the light input edge114of the light guide102for flat light guides or along a surface contour for non-flat light guides.

Micro-optical elements at the light input region are shaped to predictably refract light incident thereon. However, one or more of the surfaces of the micro-optical elements may be modified, such as roughened, to produce a secondary effect on light incident thereon. Exemplary micro-optical elements are described in U.S. Pat. No. 6,752,505 and, for the sake of brevity, will not be described in detail in this disclosure. The micro-optical elements for the light input region may vary in one or more of size, shape, depth or height, density, orientation, slope angle, or index of refraction such that a desired optical modifying characteristic is achieved over the corresponding light input region.

In the illustrated embodiment, light input region118includes a planar surface. As such, the light input region118provides little or no modification of the light ray angle distribution of the light incident thereon beyond that resulting from refraction at a plane surface. The light input region118is therefore considered specularly transmissive. In other embodiments, light input region118includes optical elements that are different than the optical elements119in light input region117to provide a light ray angle distribution modification different than that provided by the light input region117.

The lighting assembly100further includes a light source assembly103(e.g., as shown inFIGS. 1 and 2). The light source assembly103includes one or more light sources104positioned adjacent the light input edge114. Each light source104is typically embodied as one or more solid-state devices. In one embodiment, the light sources104are mounted to a printed circuit board (PCB)105(e.g., as shown inFIG. 1). Accordingly, the light sources104are fixed in position relative to one another. As described in greater detail below, the light sources104and the light input edge114of the light guide102are variably positionable relative to one another.

In some embodiments, the light sources104are positioned relative to the light input regions117,118such that the apportionment of the light from each light source104between the light input regions117,118associated with the light source is the same for all the light sources. Consequently, the light entering the light guide102has the same characteristic (e.g., spectrum and/or light ray angle distribution) regardless of the light source from which it originated.

Exemplary light sources include such solid state devices as LEDs, laser diodes, and organic LEDs (OLEDs). In an embodiment where the light source104includes one or more LEDs, the LEDs may be top-fire LEDs or side-fire LEDs, and may be broad spectrum LEDs (e.g., emits white light) or LEDs that emit light of a desired color or spectrum (e.g., red light, green light, blue light, or ultraviolet light). In one embodiment, the light source104emits light with no operably-effective intensity at wavelengths greater than 500 nanometers (nm) (i.e., the light source104emits light at wavelengths that are predominantly less than 500 nm). In some embodiments, each light source104included in the lighting assembly100has the same nominal spectrum. In other embodiments, the light sources are different from each other (e.g., two different types of light sources alternatively located along the light source assembly as will be described below with reference toFIGS. 20 and 21).

Although not specifically illustrated in detail, the light source assembly103also includes structural components (e.g., PCB105as shown inFIG. 1) to retain the light source104. The light source assembly103may additionally include: circuitry, power supply and/or electronics for controlling and driving the light source104, and any other appropriate components.

Each light source is associated with two or more light input regions of the light guide102. In the example shown, two light input regions117,118are associated with the light source104. Other examples have more than two light input regions associated with each light source. The light source104and the associated light input regions are variably positionable relative to one another such that light emitted by the light source104is incident on the light input regions117,118and is variably apportioned between the light input regions depending on the relative positioning of the light input regions117,118and the light source104. In an example, the relative positioning of the light source and the light input region is varied by moving the light source along a direction parallel to the major surfaces106,108and parallel to the light input edge114of the light guide102(in a forward direction and a reverse direction) to selectively apportion light emitted from the light source among the light input regions. In one embodiment, moving the light source in the forward direction provides output light with a first characteristic and moving the light source in the reverse direction provides output light with a second characteristic different from the first characteristic.

For example, inFIG. 4, the light source104is located adjacent the light input region117of the light input edge114. Therefore, more of the light emitted from the light source104is incident on the light input region117than is incident on the light input region118. As further shown inFIGS. 5 and 6, the light source104has been moved laterally by respective distances relative to the position shown inFIG. 4to vary the position of the light source104relative to the light guide102and produce a corresponding change in the apportionment of the light incident on the light input regions. For example, inFIG. 5the light source104is located adjacent the light input region118of the light input edge114. Therefore, more of the light emitted from the light source104is incident on the light input region118than is incident on the light input region117. InFIG. 6, the light source104is located in an intermediate position adjacent both the light input region117and the light input region118of the light input edge114. Therefore, similar amounts of the light emitted from the light source104are incident on the light input region117and the light input region118. By moving the light source104and the associated light input regions117,118relative to one another, light emitted from the light source is selectively apportioned between the light input regions so that a characteristic of the light output from the lighting assembly is modified based on the optical modifying characteristics of the light input regions117,118and the relative positioning of the light source104and the light input regions117,118.

In one embodiment, the relative positioning is varied manually by a user. In the example shown inFIG. 1, the lighting assembly100includes a user-manipulable mechanism147that moves one or both of the light guide102and the light source104relative to the other to vary the relative positioning of the light input regions and the light source104. As shown inFIG. 1, the light source104is fixed relative to a housing140and the light guide102is rotatably moveable relative thereto by the manual application of force to the mechanism147. In the embodiment ofFIG. 1, the mechanism147is a member that is secured to the light guide102and slides over a portion of the housing140of the light bulb200. In one embodiment, the amount of movement may be limited by stops (not shown). Other manually-operated mechanisms are possible. For instance, other types of sliders may be employed or a turnable knob may act on the moveable component through a gear or drive train. In other embodiments, the mechanism147is motorized to move one or both of the light guide102and the light source104relative to the other. The motorized mechanism may be controlled by a control assembly (not shown) to adjust light output based on user input, feedback from sensors, or a triggering event. In still other embodiments, there is no mechanism147and the adjustment is made by applying a positioning force, which in the case of the exemplary cylinder is torque, directly to the moveable one of the light source assembly103and the light guide102.

Once positioned, the relative positioning of the light input regions and the light source104remains unchanged until the user or control assembly varies the relative positioning. Since constant motion of the light guide102and the light source104relative to one another is not contemplated during operation of the lighting assembly100, the range of movement of the light guide102and/or the light source104may be limited. The range of movement may be limited to back-and-forth sliding that moves the light input regions117,118in and out of alignment with the light source104, rather than allowing infinite movement of the light guide102or the light source104in one direction.

A visual indicator may be present to provide the user with an indication of the modification of the light output of the lighting assembly100. In the illustrated embodiment ofFIG. 1, for example, markings146are present on the light guide102and align relative to a pointer148on the housing to provide this indication.

FIGS. 7-10illustrate part of another embodiment of a lighting assembly with an adjustable light output. More specifically,FIGS. 7-10illustrate an exemplary application in which the light ray angle distribution of the light input to the light guide are modified such that that the light ray angle distribution of the light output from the lighting assembly depends on the relative positioning of the light source and the light input regions.

In the embodiment shown inFIGS. 7 and 8, the lighting assembly is similar to that illustrated inFIGS. 3-6, but the light input regions117,118are located at a recessed portion of edge114. The recessed position of the light input regions117,118does not change the effect of the optical modifying characteristics of the light input regions117,118on the light incident thereon, but the recessed configuration is simply shown to illustrate that the light guide102may be any suitable shape. Light input region117includes optical elements119illustrated as lenticular grooves oriented parallel to the major surfaces106,108. Light input region118includes a planar surface.

FIGS. 7 and 9illustrate a relative positioning of the light source104and the light input edge114wherein more of the light emitted from the light source is incident on light input region117than on light input region118. Referring first toFIG. 7, light input region117includes lenticular grooves oriented parallel to the major surfaces106,108. The lenticular grooves change the light ray angle distribution of the light emitted from the light source104and incident on the first light input region117. The lenticular grooves spread the light entering the light guide102through the light input region117in a plane orthogonal to the major surfaces106,108and the light input edge114. Referring now toFIG. 9, more of the light entering the light guide102is incident on the major surfaces106,108at smaller angles of incidence (relative to the normal) due to refraction of the light at the optical elements119and therefore more of the light propagates in higher modes in the light guide102. As described above, the first and second major surfaces106,108include light extracting elements (not shown). As a result of the greater amount of light propagating in the higher propagation modes, more of the light emitted from the light source and incident on the first light input region117exits through one or both of the first major surface106and the second major surface108than through the edge116, as illustrated inFIG. 9.

FIGS. 8 and 10illustrate a relative positioning of the light source104and the light input edge114wherein more of the light emitted from the light source is incident on the light input region118than is incident on the light input region117. Referring first toFIG. 8, the light input region118has a planar surface. The planar surface of the light input region118is specularly transmissive. Referring now toFIG. 10, more of the light entering the light guide102through the light input region118is incident on the major surfaces at larger angles of incidence (relative to the normal) and therefore more of the light propagates in the light guide at lower modes in the light guide. As a result of the greater amount of light propagating in the lower propagation modes, more of the light emitted from the light source104and incident on the second light input region118exits the light guide102through the edge116than through the major surfaces106,108.

The above-described embodiments exemplify modification of the light ray angle distribution of the light input to the light guide102and, hence, the light ray angle distribution of the output light. The following embodiments provide examples of modification of the spectrum of the light incident on the light input regions.FIGS. 11-13illustrate an example of a light input edge114having three light input regions217,218,219, wherein at least one of the input regions includes a spectrum adjuster. Accordingly,FIGS. 11-13illustrate an embodiment where the variable positioning of light source104and the associated light input regions relative to one another determines a modification of the spectrum of the light input to the light guide102.

In the illustrated embodiment, the light input region217includes a spectrum adjuster, and the light input region219includes a spectrum adjuster that is different than the spectrum adjuster of the light input region217. The presence of the respective spectrum adjusters in the light input regions217,219is denoted by hatching. Light input region218is specularly transmissive and does not adjust spectrum. However, embodiments are contemplated where the light input region218also includes a spectrum adjuster.

In one embodiment, the respective spectrum adjuster in the light input regions is a region of wavelength shifting material. Wavelength shifting is used herein to refer to a process in which a material absorbs light of certain wavelengths, and reemits light at one or more different wavelengths. The wavelength-shifting material includes one or more of a phosphor material, a luminescent material, a luminescent nanomaterial such as a quantum dot material, a conjugated polymer material, an organic fluorescent dye, an organic phosphorescent dye, and lanthanide-doped garnet. In another embodiment, the respective spectrum adjuster in the light input regions is a region of color attenuating material, for example, a color filter. In other embodiments, the light input regions respectively include both a wavelength shifting material and a color attenuating material. For example, the spectrum adjuster of one of the light input regions may include a wavelength shifting material and the spectrum adjuster of another of the light input regions may include a color attenuating material.

Similar to the above-described embodiments, the light source104and the light input regions217,218,219are variably positionable relative to one another such that light emitted from the light source and incident on the light input regions is apportioned among the light input regions depending on the relative positioning of the light input regions217,218,219and the light source104. Accordingly, the light source104may be located adjacent the light input edge in a position corresponding to any one of the light input regions217,218,219. For example, inFIG. 11, the light source104is located adjacent the light input region217of the light input edge114such that more of the light emitted from the light source104is incident on the light input region217than on the light input regions218,219. InFIG. 12, the light source104is located adjacent the light input region218of the light input edge114such that more of the light emitted from the light source104is incident on the light input region218than on the light input regions217,219. Similarly, when the light source104is located adjacent the light input region219of the light input edge114, more of the light emitted from the light source104is incident on the light input region219than on the light input regions217,218. Light emitted from the light source104and incident on the input region217is input to the light guide with a first spectrum, light emitted from the light source and incident on the light input region218is input to the light guide with a second spectrum, and light emitted from the light source and incident on the light input region219is input to the light guide with a third spectrum, in accordance with the light modifying characteristics of the respective light input regions.

The light source104may also be located adjacent a region of the light input edge114in an intermediate position between two adjacent ones of the light input regions217,218,219. For example, inFIG. 13, the light source104is located in an intermediate position adjacent both the light input region218and the light input region219of the light input edge114such that a portion of the light emitted from the light source104is incident on the light input region218and another portion (typically the remainder) of the light emitted from the light source is incident on the light input region219. Accordingly, the light input to the light guide with different spectra from the respective light input regions mixes in the light guide to provide light with a spectrum that is the sum of the spectra of light input to the light guide102through the light input regions218,219weighted in accordance with the apportioning of the light between the light input regions218,219.

FIGS. 14-16illustrate an exemplary application of the lighting assembly100as described with reference toFIGS. 11-13. More specifically,FIGS. 14-16illustrate an application in which the spectrum of the light output from the lighting assembly is modified based on relative positioning of the light source104and the light input regions217,218,219. The application will be described with reference to an example in which the color temperature of the output light from the lighting assembly100is varied.

Many LED light sources104emit light in a range of wavelengths intended to achieve a corresponding color temperature. However, within batches of LEDs having the same nominal color temperature, there is variation of color temperature from LED to LED. Also, sometimes broad-spectrum LEDs (e.g., “white light” LEDs) or groups of tri-color LEDs (e.g., a red LED, a blue LED and a green LED whose outputs combine to produce white light) do not produce a color temperature that is desirable to a user or appropriate for a certain lighting application. To modify the color temperature of the light output from the lighting assembly100, the light input region217and the light input region219may be used to modify the spectrum (color temperature in this case) of the light output by the lighting assembly100. In this example, the light input region217modifies the light output to be warmer (either or both of more red and less blue) and the light input region219modifies the light output to be cooler (either or both of more blue and less red). The light input region218is specularly transmissive, and light incident thereon enters the light guide with the same spectrum (color temperature in this case) as the light emitted from the light source104. The relative positioning of the light source104and the light input regions217,218,219(as illustrated inFIGS. 14-16) varies the apportionment of the incident light between the light input regions, therefore resulting in a corresponding variation in color temperature of the light output from the lighting assembly100.

Some embodiments are configured to allow a user to vary the color temperature of light output from the lighting assembly100in order to achieve a desired color temperature. Other embodiments are configured to allow a manufacturer of the lighting assembly100to vary the color temperature of light output from the lighting assembly100to compensate for different color temperatures associated with different lots of light sources104. This allows the lighting assembly manufacturer to source a broader range of light sources104from one or more suppliers and still manufacture lighting assemblies with a defined, consistent color temperature.

In some embodiments, the relative positioning of the light input regions217,218,219and the light source104is varied by the manufacturer of the lighting assembly100until the output light has a defined characteristic. The relative positioning is then fixed by the manufacturer, and the lighting assembly100is configured in a manner to minimize the ability of a user of the lighting assembly100to further vary the relative positioning. In other embodiments, the user has the ability to vary the relative positioning.

Embodiments are also contemplated where one or more of the respective light input regions associated with a light source modifies both the spectrum and the light ray angle distribution of the light incident thereon.FIG. 17illustrates an exemplary configuration of light input regions217,218,219and317,318,319of light input edge114, wherein at least one of the input regions includes a spectrum adjuster and optical elements. Similar to the light input regions described above with reference toFIGS. 11-13, light input regions217,219each include spectrum adjusters, and light input region218is specularly transmissive. Light input region317includes a spectrum adjuster similar to the spectrum adjuster of light input region217, and light input region319includes a spectrum adjuster similar to the spectrum adjuster of light input region219. In addition, light input regions317,318,319include optical elements220that modify the light ray angle distribution of the light incident thereon. In the illustrated embodiment, the optical elements220of light input regions317,318,319are similar.

The relative positioning of the light source104and the light input regions217,218,219modifies the spectrum of the light input to the light guide102with a first light ray angle distribution, and the relative positioning of the light source104and the light input regions317,318,319modifies the spectrum of the light input to the light guide102with a second light ray angle distribution, different from the first light ray angle distribution.

In the above-described examples, the boundaries between the adjacent light input regions are depicted as extending orthogonally to the plane of the major surfaces106,108. In other examples (not shown), the boundaries of the light input regions extend non-orthogonally to the plane of the major surfaces106,108. In one particular example, the boundaries slope towards one another, allowing the light from the light source104to be apportioned among three light input regions depending on the relative positioning of the light source104and the light input regions along a direction parallel to the major surfaces106,108of the light guide102.

The embodiments described thus far have illustrated relative positioning of the light source104and light input regions along one direction (i.e., along a direction parallel to the major surfaces106,108of the light guide102and the light input edge114(e.g.,FIGS. 4-6)). As illustrated inFIGS. 18 and 19, the light source104and light input regions are variably positionable relative to one another along two directions (i.e., along a direction parallel to the major surfaces106,108of the light guide102, and along a direction orthogonal to the major surfaces106,108of the light guide102). Accordingly, two variables are provided for modifying the characteristics of the light output of the lighting assembly100. In the examples shown inFIGS. 18 and 19, light input regions are arrayed along both the first direction131and second direction132relative to light input edge114of the light guide. The light source104and light input regions are relatively positionable along two directions131,132to apportion the light emitted from the light source between two, three or four of the light input regions.

FIG. 18illustrates an embodiment having three light input regions417,418,419.FIG. 19illustrates an embodiment having four light input regions417,418,419,420. Consistent with the above-described embodiments, one or more of the respective light input regions includes optical elements and/or a spectrum adjuster.

In one embodiment, the relative positioning of the light source104and the light input regions along the first direction131provides a first modification of the spectrum, and the relative positioning of the light source and the light input regions along the second direction132, in the example shown, orthogonal to the first direction, provides a second modification of the spectrum, different from the first modification of the spectrum. In an example of the embodiment shown inFIG. 18, the light input regions417,418include respective spectrum adjusters and the light input region419is specularly transmissive and does not adjust spectrum. The relative positioning of the light source104along the two directions131,132apportions the light from the light source among the light input regions417,418,419to provide a desired light output spectrum from the lighting assembly100.

In another embodiment, moving the light source along the first direction131modifies the light ray angle distribution and moving the light source along the second direction132modifies the spectrum. In an example of the embodiment shown inFIG. 19, light input regions417,418include similar spectrum adjusters, and light input regions418,420include similar optical elements. Light input region419is specularly transmissive and does not adjust spectrum. By moving the light source along the first direction131, output light with a desired light ray angle distribution is obtained. By moving the light source along the second direction132, output light with a desired light output spectrum is obtained. By moving the light source along the first direction131and the second direction132, output light with a desired combination of light ray angle distribution and spectrum is obtained.

FIGS. 20 and 21illustrate another embodiment in which the lighting assembly includes multiple types of light sources204,304. In this embodiment, the two types of light sources are alternately located along the light input edge114of the light guide102. Light sources of a first light source type204emit light with a first spectrum, and light sources of a second light source type304emit light with a second spectrum, different from the first spectrum. For example, in one embodiment, the light sources of the first light source type204emit “white” light and the light sources of the second light source type304emit red light. The light sources204,304are mounted on a common PCB (not shown) such that the light sources and the associated light input regions of the light guide102are positionable relative to one another in concert. Light emitted from each light source204,304is incident on one or more light input regions.

Two types of light input regions517,518are alternately located along the input edge114of the light guide102. The light input regions of a first light input region type517have a first transmissivity and the light input regions of a second light input region type518have a second transmissivity, different from the first transmissivity. In one embodiment, light input region types517,518include at least one of a reflective material and a light absorbing material to reduce the intensity of light input into the light guide102.

In the illustrated example, the lighting assembly100is configured such that, for a given positional relationship between the light sources204,304and the light input regions517,518, the apportionment of the light from each type of light source between the light input regions is the same. For example,FIG. 20illustrates a relative positioning wherein more of the light emitted from the light sources204of the first light source type is incident on the light input regions517of the first light input region type than on the light input regions518of the second light input region type; and more of the light emitted from the light sources304of the second light source type is incident on the light input regions518of the second light input region type than on the light input regions517of the first light input region type.

FIG. 21illustrates a relative positioning of the light sources and the light input regions wherein a portion of the light emitted from the light sources204of the first light source type and a portion of the light emitted from the light sources304of the second light source type are incident on a same one of the light input regions517,518of the first and second light input region types. Light input to the light guide102from the light sources204of the first light source type and light input to the light guide102from the light sources304of the second light source type mix in the light guide to provide light with a spectrum that is the sum of the spectra of light input to the light guide102from the light sources204,304of the first and second light source types weighted in accordance with the apportioning of the light between the light input regions of the first and second light input region types. In the illustrated example, the transmissivity of the respective light input regions517,518of the first and second light input region types and the relative positioning of the light sources204,304of the first and second light source types collectively control a characteristic (in this example, spectrum) of the light output from the lighting assembly100.

Other applications are apparent based on using any of the above-noted light modifying characteristics for the light input regions.

Returning toFIG. 1, additional details regarding the lighting assembly100when embodied as the light bulb200will be described. The light bulb200includes a base150. The illustrated base150is an Edison base, but other types of bases150may be used, including any commercially-standard base or proprietary base used for mechanically securing an incandescent bulb, a fluorescent bulb, a compact fluorescent bulb (CFL), a halogen bulb, a high intensity discharge (HID) bulb, an arc lamp, or any other type of bulb into a lamp, a lighting fixture, a flashlight, a socket, etc., and/or for supplying electricity thereto. The light bulb200typically further includes a heat sink151that dissipates heat generated by the light sources104. The heat sink151of the illustrated embodiment forms part of the housing140. Parts of the light bulb200, such as the light guide102and the light source104, are described above with reference toFIGS. 3-21.

References herein to a “light bulb” are meant to broadly encompass light-producing devices that fit into and engage any of various fixtures for mechanically mounting the light-producing device and for providing electrical power thereto. Examples of such fixtures include, without limitation, screw-in fixtures for engaging an Edison light bulb base, a bayonet fixture for engaging a bayonet light bulb base, or a bi-pin fixture for engaging a bi-pin light bulb base. Thus the term “light bulb,” by itself, does not provide any limitation on the shape of the light-producing device, or the mechanism by which light is produced from electric power. Also, the light bulb need not have an enclosed envelope forming an environment for light generation. The light bulb may conform to American National Standards Institute (ANSI) or other standards for electric lamps, but the light bulb does not necessarily have to have this conformance.

Returning toFIG. 2, additional details regarding the lighting fixture300will be described. The lighting fixture300may be a hanging light (as shown), a ceiling light (e.g., an assembly to fit in a drop-down ceiling or secure flush to a ceiling), a wall sconce, a table lamp, a task light, or any other illumination device. The lighting fixture300includes a housing140for retaining the light source assembly103and the light guide102. The housing140may retain or may serve as a heat sink. In some embodiments, the lighting fixture300includes a mechanism160(e.g., a chain or wire in the case of a hanging light, clips or fasteners in the case of a ceiling light or wall sconce, etc.) to mechanically secure the lighting assembly to a retaining structure (e.g., a ceiling, a wall, etc.). In other embodiments, the mechanism160is a stand and/or base assembly to allow the lighting fixture300to function as a floor lamp, table lamp, task lamp, etc. Electrical power is supplied to the lighting fixture through appropriate conductors, which in some cases may form part of or pass through the mechanism160. Parts of the lighting fixture, such as the light guide102and the light source104, are described above with reference toFIGS. 3-21.

In this disclosure, the phrase “one of” followed by a list is intended to mean the elements of the list in the alterative. For example, “one of A, B and C” means A or B or C. The phrase “at least one of” followed by a list is intended to mean one or more of the elements of the list in the alterative. For example, “at least one of A, B and C” means A or B or C or (A and B) or (A and C) or (B and C) or (A and B and C).