权利要求：
1. A lighting device including: at least one light emitter, at least one light source, and at least one light conductor arranged to conduct light from the light source to the light emitter;
the light emitter including a translucent body and a first reflector, the first reflector being connected to or integral with the translucent body;
the translucent body including a first emitter portion, a first incident portion, and a spherically curved surface, the spherically curved surface defining a first emitter lens of the first emitter portion and a first incident lens of the first incident portion;
the first incident portion being arranged to conduct light emitted from an emission surface of the light conductor, via the first incident lens, to the first reflector;
the first reflector being arranged to reflect the light emitted from the emission surface of the light conductor to exit the light emitter as a beam of light via the first emitter lens;
wherein the light emitter is rotatable with at least two degrees of freedom relative to the light conductor to direct the beam; and
wherein the light emitter is spaced apart from the light conductor to define a separation distance (S) between the emission surface and the first incident lens, the separation distance (S) being selected relative to a distance between the light emitter and a target surface so that the first incident lens and first emitter lens form a conjugate imaging system with a target plane at the target surface and an object plane at the emission surface of the light conductor; and wherein either
(i) an object is arranged between the light conductor and the light emitter, and the lighting device is arranged to project an image of the object onto the target surface, or
(ii) the light conductor has a cross section which defines a cross sectional shape of the beam, and the lighting device is arranged to project a correspondingly shaped, sharply defined pool of light onto the target surface; and
wherein either
(i) an adjustment means is provided for varying the separation distance (S), or
(ii) a variable focus optical element is arranged between the first incident lens and the object plane at the emission surface.
2. A lighting device according to claim 1, wherein said object is arranged between the light conductor and the light emitter, and the lighting device is arranged to project said image of the object onto the target surface.
3. A lighting device according to claim 1, wherein the light conductor has said cross section which defines said cross sectional shape of the beam, and the lighting device is arranged to project said correspondingly shaped, sharply defined pool of light onto the target surface.
4. A lighting device according to claim 3, wherein the cross section is a non-circular cross section.
5. A lighting device according to claim 1, wherein
(i) said object is arranged between the light conductor and the light emitter, and the lighting device is arranged to project said image of the object onto the target surface, and
(ii) the light conductor has said cross section which defines said cross sectional shape of the beam, and the lighting device is arranged to project said correspondingly shaped, sharply defined pool of light onto the target surface.
6. A lighting device according to claim 5, wherein the cross section is a non-circular cross section.
7. A lighting device according to claim 1, wherein the first emitter lens defines a first emitter axis, and the first emitter lens extends over at least most of a total section area of the light emitter normal to the first emitter axis when viewed along the first emitter axis.
8. A lighting device according to claim 1, wherein the first incident lens defines a first incident axis, and the first incident lens extends over at least most of a total section area of the light emitter normal to the first incident axis when viewed along the first incident axis.
9. A lighting device according to claim 1, wherein the lighting device includes at least one support element,
and the curved surface of the translucent body is slidably mounted on the support element to support the light emitter in rotation with said at least two degrees of freedom relative to the support element.
10. A lighting device according to claim 9, wherein the support element comprises the light conductor.
11. A lighting device according to claim 1, wherein the first reflector is located within the translucent body.
12. A lighting device according to claim 1, wherein the translucent body is spherical.
13. A lighting device according to claim 1, wherein the light conductor is a body of solid translucent material.
14. A lighting device according to claim 1, wherein an outer tubular waveguide shell is arranged around the light conductor to conduct a portion of the light from the light source.
15. A lighting device according to claim 1, wherein the lighting device includes a base and the light source is arranged at the base, and in a normal use position the light conductor extends vertically upwardly from the base and the light emitter is supported above an upper end of the light conductor.
16. A lighting device according to claim 1, wherein the cross section is a non-circular cross section.
具体实施方式：
[0055]Reference numerals occurring in more than one of the figures indicate the same or corresponding elements in each of them.
[0056]In this specification, a three dimensional surface is considered to have spherical curvature if it could be extended to form a sphere, and the origin of the curved surface is the point at which its radii intersect and which would be the centre of the sphere.
[0057]In this specification, the term translucent is taken to include transparent. The translucent body of the or each light emitter is advantageously transparent, as are the light conductors and other translucent elements such as bearing materials, but any or all of them could alternatively be translucent but not transparent, e.g. diffusive, as required for the particular application.
[0058]The novel lighting device can be arranged in various configurations to define for example a ceiling mounted downlighter, a wall lamp, a desk lamp or standard lamp, a street lamp, or a stage light for use in illuminating a performer.
[0059]FIG. 1 shows how a light emitter 100 can be supported by a support element 20 configured as a flat plate with fixing means 21 for fixing it in a use position in spaced relation to a support surface. The plate may be arranged horizontally so that the lighting device can be used as a downlighter beneath a ceiling or other horizontal surface.
[0060]The fixing means may be configured to suspend the lighting device from the support surface so that it can be used without any suspended ceiling system. Alternatively of course the fixing means may be arranged to support the lighting device in a framework so that the support plate forms a tile in a suspended ceiling system.
[0061]In addition to the light emitter 100 and support element 20, the lighting device includes a light source 30, which may comprise a single LED or other light generating device or an array of several such devices, and a light conductor 40 which is arranged to conduct light from the light source to the light emitter. Optionally, in this and other embodiments, a controlled proportion of the transmitted light may be emitted from local discontinuities in the body or outer surface of the light conductor 40 to provide ambient illumination of a ceiling or reflector above the suspended device.
[0062]The light emitter includes a translucent body 101 and a first reflector 102 which is connected to or integral with the translucent body. As best seen in FIGS. 3, 4 and 6, the translucent body includes at least a first emitter portion 103 defining a first emitter surface 104 which is shaped to define a first emitter lens 105. The first reflector 102 is arranged to reflect light emitted from the light conductor 40 to exit the light emitter as a beam of light via the first emitter lens 105, and the light emitter is rotatable with at least one degree of freedom relative to the light conductor 40 and support element 20 to direct the beam.
[0063]The translucent body 101 of the light emitter may be a solid, translucent glass or plastic sphere, variously referred to hereinafter as a ball optic, which contains the first reflector 102. The reflector can be a flat mirror or other reflective element embedded in the ball optic, for example, a disc (as shown in FIG. 1B) which is arranged between the opposed flat surfaces of two generally hemispheric portions of the optic, or it could be the reflective surface of an optical discontinuity such as a slot formed in the optic.
[0064]In this and other embodiments, the light emitter may include at least one second reflector 122, as further described below and particularly with reference to FIGS. 38A and 38B. Where the light emitter includes more than one reflector, the reflectors may be positioned differently with respect to the centre of rotation of the light emitter or the central axis of the light conductor, or may have different characteristics. For example, each reflector may be flat or curved, and parallel or nonparallel. For example, one reflector could be flat and the other curved. The reflectors may be arranged so that the light emitter can be rotated to reflect the light from the light conductor selectively from one or other of them, or simultaneously from both or all of them. Each reflector may be specular or diffuse or Lambertian. By providing reflectors with different characteristics, the user may rotate the light emitter for example to obtain a broad, diffuse beam or a concentrated spot. The translucent body 101 of the light emitter may similarly include different regions; for example, it may be partially transparent and partially non-transparent or diffusive, or it may include void spaces, liquid filled spaces, or internal lenses to modify the light reflected from one or other of the reflectors.
[0065]The spherical light emitter 100 is mounted for rotation in a circular hole 22 in the support element, and a textured surface region configured as a knurled ring 106 is provided on its surface so that the ball optic can be engaged and rotated with one finger, as further described below.
[0066]In this and other embodiments, the light conductor 40 may be a hollow tube, preferably with a reflective inner surface and, optionally, beam transfer lenses spaced apart along its length. More preferably however the light conductor is a body of solid translucent material which functions as an optical waveguide to conduct light by total internal reflection. The waveguide may be a parallel sided rod or tube with a circular, elliptical, polygonal or other non-circular cross section, or a flat or curved sheet, made for example of glass, acrylic or other suitable plastics material. In each case, the light conductor may function as a support element to support the light emitter as it is rotated by the user, or a separate support element may be provided as exemplified by the embodiment of FIG. 1.
[0067]FIG. 2 illustrates how the LED or other light source 30 launches light into the light conductor 40 comprising a solid optically refractive waveguide rod, made for example from glass or acrylic. Light is captured within the waveguide via Fresnel refraction; as appropriate the endface of the rod at the location of launching may be shaped or curved i.e. other than a planar endface, to achieve certain guidance conditions that may be needed for the lighting task. Optionally, an additional coupling optic (not shown) might be used between the light source and the waveguide to form the desired family of rays within the waveguide and to maximise coupling of light into the system. In these regards it can be understood that establishing a certain family of guided rays within a waveguide lighting system may be desirable in order to achieve a specific objective for the lighting system such as for example, good uniformity of projected illuminance in the task plane. For example, it may be desirable to achieve a family of rays that are all guided at low angles to the optical axis with no extremal rays propagating at high angles to the axis, alternatively it may be desirable to exclude the presence of rays guided at low angles and establish rays at a high angle etc.; the choice of guided ray family will depend upon the specific lighting task and aesthetic to be achieved by the lighting system, and may be determined for example by a ray trace optimisation procedure.
[0068]FIG. 2 also illustrates how the waveguide may optionally be configured to scatter some of the light from internal and surface discontinuities so that the scattered fraction leaks out from the sides of the waveguide to provide weak ambient lighting as further described below.
[0069]Preferably, all or most of the light emitted by the light source 30 is coupled into the waveguide as known in the art to form a well-defined family of rays which are guided by refraction and total internal reflection, which for acrylic and glass is typically within a cone angle of about 50 degrees centred on the length axis L1 of the waveguide, so that rays outside the desired angular range are not conducted to the light emitter 100. It should be noted that depending on the specific nature of the optical launch into the waveguide it is possible either to establish and maintain a specific family of guided light rays, or instead to scramble the ray paths within the guide, according to the lighting effect to be achieved.
[0070]For example, random mixing of the rays propagating in the guide may advantageously prevent the light source 30 from being imaged when observed from within the beam leaving the light emitter, so that LEDs or other point light sources can be used without dazzling or causing a persistent retinal image. As an example, such random mixing might be achieved by applying a diffuse surface finish to the launch end of the waveguide rod.
[0071]Alternatively, and in the absence of a diffusing structure within the launch, it is possible to establish and maintain a fixed set of ray paths in the guide that can usefully convey desired features from the light source (such as the light output from individual LED dies) to the distal end of the waveguide rod. As an example of the latter scenario using well defined ray paths, there may be a desire to deliver an aesthetically pleasing pattern of light from the light source 30 to the task plane.
[0072]Referring to FIG. 3, in these and other embodiments, the first emitter lens 105 is preferably convexly curved without inflections to define a central optical axis, referred to as the first emitter axis E1. The first emitter lens preferably extends over at least most of a total section area of the light emitter normal to the first emitter axis E1 when viewed along the first emitter axis. In FIG. 3 it can be seen that the first reflector occupies the total section area of the light emitter when viewed along the first emitter axis. Most preferably, the emission surface defining the first emitter lens is spherically curved, as shown.
[0073]Preferably the translucent body also includes a first incident portion 107 which is arranged to conduct light emitted from the light conductor to the first reflector. Preferably the incident surface 108 of the first incident portion is shaped to define a first incident lens 109, so that the light incident on the first incident surface is focused by the first incident lens before being reflected and then focused again by the first emitter lens before it is emitted as a beam from the first emitter surface.
[0074]Preferably as shown in the example of FIG. 3, the incident surface defining the first incident lens is convexly curved without inflections and defines a central optical axis, referred to as the first incident axis I1, and the first incident lens extends over at least most of a total section area of the light emitter normal to the first incident axis I1 when viewed along the first incident axis. Preferably the first incident lens is spherically curved, as shown.
[0075]As exemplified by the embodiment of FIG. 3, the first emitter and incident portions and first emitter and incident lenses may be combined so that they have a common axis E1, I1. The light emitter is rotationally adjustable with preferably two or three degrees of freedom relative to the support element 20 and light conductor 40 as indicated by the curved arrows, so that different parts of the combined, spherical emitter and incident surfaces will receive light from the light conductor and emit light through the circular hole 22 in the support element, depending on the rotational position of the light emitter 100.
[0076]Preferably the first emitter portion 103 is a solid region of the translucent body 101 of the light emitter which extends between its first emitter surface 104 and the first reflector 102, and the first incident portion 107 is a solid region of the translucent body 101 of the light emitter which extends between its incident surface 108 and the first reflector 102. The respective portions thus define two large incident and emitter lenses which by virtue of their curvature and the refractive index of the material of the translucent body (typically glass, acrylic or other plastics material) bring into play a wide range of refractive optical effects depending upon how refraction is managed through the optical system. Notably, the lens like functioning of the Incident and emitter lens structures can be used to determine the size of the exit beam cone of light; for example, reducing the radius of curvature of the emitter surface yields increasingly wider exit beam cones compared to using a larger radius of curvature.
[0077]Furthermore, by spacing the incident surface 108 apart from the emission surface (end face) 41 of the waveguide light conductor 40 by a separation distance S, it is possible to project a sharply defined pool of light onto the target surface, wherein the separation distance S is selected according to the distance between the light emitter 100 and the target plane so that the large incident and emitter lenses form a conjugate imaging system with the emission surface 41 as its object plane. The cross sectional shape of the waveguide light conductor 40 may be selected to define a suitably shaped beam so that the pool of light is for example circular or rectangular as required for the application, e.g. to illuminate a rectangular desk surface or a rectangular surface for use as a ball game court. As further explained below, the same system may be adapted to project an image from the object plane onto the target plane.
[0078]At the same time, by making the incident and first emitter surfaces smooth and with uniform, preferably spherical curvature, it is possible to angularly adjust the beam by rotating the light emitter (including its integral reflector) relative to the light conductor 40, without altering the focus of the beam or other optical parameters of the system as the beam traverses different regions of the first emitter and incident portions of the translucent body 101. Moreover, the light emitter can slide smoothly on its support element 20 during adjustment so as to maintain a constant separation distance 5, as discussed in more detail below.
[0079]When illuminated by the family of rays emitted from the end of the waveguide, which may be randomly mixed within the waveguide and which are confined by conduction through the waveguide within a well defined angular envelope, the light emitter can thus generate a well defined beam of the desired cone angle, for example, about 45 degrees, and with even intensity throughout its cross section and sharp cut-off at its edges.
[0080]Preferably as exemplified in the embodiments of FIGS. 1 and 3, the lighting device includes a support element 20, and the first incident lens is slidably mounted on a contact surface of the support element to support the light emitter in rotation with at least two degrees of freedom relative to the support element. The curved arrows in FIG. 1 and FIG. 3 show that in these and other embodiments the spherical light emitter can have three degrees of rotational freedom relative to the light conductor and support element.
[0081]As illustrated in the example of FIG. 1, in these and other embodiments, the support element 20 may be arranged for example as a plate or sheet to define a circular aperture 22, and the light emitter mounted for rotation in the aperture so that one or both of the spherically curved incident and emitter surfaces 108 or 104 slidingly engages the support element at the periphery of the aperture. This allows adjustment of the light emitter with three degrees of freedom relative to the light conductor—which is to say, the spherically curved surface of rotation can be rotated in any desired direction of rotation about its origin while remaining in sliding contact with the support element.
[0082]By arranging the light emitter in sliding contact with the support element, a self adjusting connection is provided which provides fingertip adjustment with two degrees of freedom and substantially without lost motion and which automatically compensates for wear by maintaining a constant frictional Contact between the emitter 100 and the contact surface 23 of the support element, for example, by gravity as in the illustrated examples, or by a resilient bias mechanism (not shown). The emitter 100 is securely retained (preferably being larger than the aperture 22 in the support element) and can be adjusted more precisely than prior art bendable or articulated connections which loosen with age or suffer from lost motion or mechanical lag which causes them to wander from the desired position. Of course, no electrical connection is required to the light emitter 100, so that the resulting assembly is mechanically simple and robust.
[0083]Further advantageously, the sliding interface between the incident surface of the light emitter and the contact surface 23 of the support element also provides a self cleaning action which wipes dirt from the incident surface every time the light emitter is adjusted. A similar sliding interface could be arranged if desired to clean the emission surface.
[0084]Advantageously, in these and other embodiments, the origin of the spherically curved incident surface may lie at the origin of the spherically curved emission surface. Further advantageously, the origin of one or both surfaces may lie on the first reflector, preferably in the centre of the first reflector, and on the central length axis L1 of the light conductor. This makes it possible to maintain the centre of the reflector in constant alignment with the light conductor and to provide a constant focusing power as the light emitter is rotated.
[0085]FIG. 3 illustrates how the light conductor may be spaced apart from the incident surface of the light emitter or ball optic 100 by a gap, typically an air gap. The manner in which waveguided light exits the waveguide and is transferred towards the ball optic is dependent upon the curvature of the end face 41 of the waveguide 40, the refractive index of the medium into which the rays exit directly, and the separation distance (if any) between the end of the waveguide and the ball optic.
[0086]The arrows illustrate the ray paths of waveguided light exiting from the planar end face 41 of the optical waveguide 40. For a situation of a lower refractive index medium such as air lying in the gap region, the rays may undergo further refraction as they exit the waveguide medium. Such further refraction of the exiting light can in turn impact upon how much light is coupled into the ball optic 100. For example, some strongly refracted light might miss the ball optic if the exit angle of the rays is too high. There may also be a certain amount of Fresnel back-reflection of light for the rays striking the end face 41 of the waveguide 40 due to a difference in refractive index between the waveguide and the air or other medium air in the gap. Refraction can also affect the nature of the pattern of light (or family of rays) exiting the ball optic 100 and directed towards the task plane. For example, in certain circumstances the ball optic can be arranged to form an image of the exit face of the waveguide, which may be advantageous for illumination or signalling purposes, as further described below.
[0087]For all these reasons, the waveguide end face curvature, refractive index difference between adjacent optical media, and separation distance between waveguide endface and ball optic may all be controlled to obtain the desired ray exit parameters at the distal end face 41 of the waveguide to suit particular applications.
[0088]Referring to FIG. 4, in contrast to the FIG. 3 arrangement, the curvature of the incident surface 108 of the light emitter 100 makes it possible for the incident surface to be arranged alternatively in sliding contact with the whole end face (i.e. the whole light emission surface) 41 of the waveguide 40 forming the light conductor. The curvature of the light emitter matches that of the waveguide so that Fresnel reflection resulting in leakage of light and glare at the sliding interface is minimised or eliminated.
[0089]The arrows show how ray paths exit the refractive optical waveguide into the index matched translucent body of the light emitter.
[0090]Optionally, a translucent bearing material may be arranged at the sliding interface to provide more intimate mechanical contact between the light emitter and the waveguide material, as further described below.
[0091]In the illustrated example, the refractive index values of the waveguide 40 and ball optic 100 are matched so that the rays do not undergo Fresnel refraction at the interface between the two media.
[0092]In other applications, the relative refractive indices may be unmatched. For example, the waveguide 40 may be fabricated from acrylic with a refractive index in the region of 1.5 and the ball optic 100 may be fabricated from cubic zirconia with a refractive index in the region of 2.2, enabling the ball optic to introduce refractive effects whilst maintaining physical contact between the two media.
[0093]Referring to FIG. 5, the light conductor 40 comprising a solid waveguide may be enclosed in an outer shell 50 affixed to the flat sheet which forms a support element 20. The shell 50 can be opaque (e.g. made from copper, chrome, or opaque acrylic) to capture any light leaking from the waveguide 40 and to protect its surface from dust and other contamination. Alternatively, the outer shell 50 may be translucent, for example, made from a tinted acrylic to provide uplighting to the ceiling.
[0094]FIG. 6 illustrates how the spherical light emitter 100 may be rotated with three degrees of freedom while remaining in sliding contact with the waveguide light conductor 40. The incident and emitter lenses focus the beam so that it can be used as a spotlight which is directed to the target plane by rotating the light emitter.
[0095]FIG. 7 illustrates how the waveguide rod comprising the light conductor 40 and the ball optic 100 can be separated by an adjustable separation distance. The light source 30 and light conductor 40 are mounted together on a moveable chassis support 62 that forms an adjustment means, with a handle that can be manually adjusted backwards and forwards to vary the separation distance between the end (emission) surface of the waveguide rod and the incident surface of the ball optic. This makes it possible to adjust the size of the conical beam of light exiting the ball optic, for example, to create a variable size spot of light on a target plane.
[0096]Optionally, in this and other embodiments, instead of a manual adjustment means, a motorised actuator 60 may be provided for remotely adjusting the separation distance.
[0097]The embodiment of FIG. 7 also illustrates how a powered, e.g. motorised actuator 66 can be provided for rotating the light emitter relative to the light conductor. In this way for example the light emitter may be configured as an elevated stage light with the light source being positioned at a lower level and connected to the light emitter via a vertical or inclined light conductor, and remotely controlled to direct the beam.
[0098]FIG. 8 shows how an autofocus mechanism can allow the ball optic and waveguide rod to remain in physical contact with each other while allowing the refraction of light between the waveguide and ball optic to be adjusted. In the example illustrated, a variable focus liquid lens 63 (as taught for example in EP1674892 and other patents to Varioptic SA) is placed between the waveguide and the incident surface of the ball optic 100. It can be seen that the exit window 64 of the liquid lens chamber has a radius of curvature that matches that of the ball optic. The focal length of the liquid lens can be altered by changing the relative curvature of the surface of an oil droplet inside the chamber by means of a variably applied voltage from a voltage source 65, allowing remote control via a low current wire connection, for example, in stage lighting applications where it is desired to minimise weight and mechanical complexity in the elevated light emitter.
[0099]This system allows for the size of the cone of light leaving the optical system to be adjusted automatically without the need to physically translate the waveguide end face 41 relative to the ball optic 100. This can be used to change the spot size on the target plane, for example, where the lighting device is configured as a reading light or to illuminate an artwork in a museum or gallery.
[0100]Other variable focus optical elements nay be used instead of a liquid lens. For example, a so-called “solid tuneable lens” could be used, comprising a pair of translucent plates with opposed, equally and oppositely curved surfaces, as disclosed by Yongchao Zou, Wei Zhang, Fook Siong Chau, and Guangya Zhou, “Miniature adjustable-focus endoscope with a solid electrically tunable lens,” Opt. Express 23, 20582-20592 (2015).
[0101]When the plates are perfectly aligned, they behave as one unit without any focusing power—any wave phase shift induced by one plate is cancelled out by the other. However, when the plates are slightly offset to each other in a transverse direction (across the optical axis) the overall refractive effect of free form surfaces is to refract light like a traditional lens. The advantage of the solid tuneable lens is that the means of adjustment does not necessarily require an electrical supply and so that entire optical system can be passive (i.e. no electricity required) other than at the location of the light source.
[0102]In the above illustrated embodiments, the first reflector lies in an equatorial plane, i.e. a plane containing the centre of the spherical light emitter 100, and the central length axis L1 of the waveguide is aligned with the centre of the spherical light emitter.
[0103]Optionally in these and other embodiments, the first reflector may be arranged to reflect a first portion of the light emitted from the light conductor in a first direction to form the beam, and to allow a second portion of the light emitted from the light conductor to travel past or through the reflector in a second direction to form a second beam. Optionally, in a use position, the first beam may be directed generally downwardly and the second beam generally upwardly, for example, by arranging the waveguide obliquely as illustrated in FIG. 22 or vertically as illustrated in FIGS. 25-28, or by providing another reflector or refractor to direct upwardly the light that travels past or through the first reflector.
[0104]In each case, the reflector may be specularly reflective or diffusely reflective as desired, and may be planar or curved as appropriate to the application. The reflector may also be partially transmitting so that part of the light passes through it. The reflector may also perform optical filtering function in reflection or transmission mode. The reflector may lie on the equatorial plane of the spherical light emitter 100 or may be located away from the equatorial plane desired to achieve the required optical function.
[0105]FIG. 9 illustrates how the first reflector may be located at a distance from the centre of the spherical light emitter, and/or the length axis of the waveguide also may not coincide with the centre of the spherical light emitter. Various lighting effects are produced as the light emitter is rotated.
[0106]FIG. 10 shows another example of a lighting device in which the various optical axes of the system are not coincident with each other, including a planar first reflector whose locus does not lie within an equatorial plane of the ball optic. The more complex ray paths allow various lighting effects to be created.
[0107]In this and other embodiments, whether located at or away from the equator, the first reflector may extend for less than the full diameter of a spherical light emitter. For example, it may only occupy a central area of the spherical light emitter, allowing a portion of the light received from the light conductor to bypass the mirror for use in eg uplighting where the portion of the non-reflected light illuminates a ceiling or wall.
[0108]The embodiment of FIG. 10 includes a secondary light conductor, preferably a waveguide 42, which receives light that is not reflected from the mirror in the ball optic 100 and conducts it for example to another ball optic. A similar arrangement can be used for example in the embodiment of FIG. 23 where more than one ball optic is illuminated from a common light source. The light can bypass the first reflector or pass through the first reflector if it is partially transmissive before entering the secondary waveguide 42.
[0109]FIG. 11 shows how the light emitter can be rotated to reflect the light off a Lambertian reflector 102, for example, for use in uplighting mode to illuminate a ceiling from which the support plate 20 is suspended. The second reflector 122 may be specular to provide a narrower beam of more concentrated light when rotated into a downlighting position.
[0110]FIG. 12A shows how a textured surface region 106 can be formed as a knurled ring, either in a plane containing the first reflector (FIG. 12A) or in a plane that intersects the first reflector (FIG. 12B). The user can engage the textured surface region to rotate the light emitter by placing one finger on the ring. The knurled ring may be recessed beneath the adjacent smooth surface of the light emitter or alternatively may stand proud of the adjacent smooth surface of the light emitter. Its position is selected so that it does not interfere mechanically with the sliding support of the light emitter or optically with the incident or emitted light in its normal use positions.
[0111]FIG. 13 shows a disc 110 which extends outwardly from the light emitter to provide a surface that can be manipulated by the user to rotate the light emitter.
[0112]FIG. 14 shows another light emitter with a textured surface region 106, which may be for example a band of a suitable material such as embossed copper, a knurled or roughened surface cut into the material of the ball optic, or a bejewelled surface structure cut just below the diameter of the ball or a region encrusted with high quality jewelled optics and crystal structures. This may provide a decorative feature, for example, when the light emitter is one of several light emitters supported by a common support element 20 to form a track lighting system.
[0113]In alternative embodiments, multiple textured surface regions may be provided, or indents may be arranged at spaced locations on the surface of the light emitter to help the user to engage and rotate it.
[0114]FIG. 15 shows an alternative adjustment arrangement in which magnets or magnet-responsive elements (e.g. steel bodies) 67 are embedded just within the diameter of the ball optic so that it can be rotated by a magnetic or magnet-responsive wand 68.
[0115]FIG. 16 shows how the light emitter can include one or more light scattering elements such as multifaceted diamond or ‘glitter ball’69, optionally on one side of a double sided reflector, to provide a decorative effect when rotated to the appropriate position.
[0116]FIGS. 17A and 17B show how the sliding contact surfaces of the light emitter and support element may be curved to match each other.
[0117]Referring to FIGS. 18A and 18B, the support element 20 may comprise a body material 24 with a contact surface 23 formed by a bearing material 25 which slidingly supports the curved surface of the light emitter. The bearing material may be relatively softer or have a lower coefficient of friction than the body material, and may be translucent to conduct light from the end face of the light conductor to the incident surface of the light emitter, for example, where the support element comprises a solid waveguide material in the form of a tube or a rod to function also as the light conductor. Even where a separate support element in provided, a similar sliding interface may be arranged between the waveguide and the light emitter.
[0118]Optionally, one of the contacting surfaces at the interface may be harder than the other, for example, by making the light emitter from glass or hard plastics material and the light conductor from a softer plastics material, or by providing either one of the surfaces with a hard or soft coating. For example, a layer of a relatively soft, optionally elastomeric, and optically translucent bearing material 25 may be applied to the surface of the waveguide at the interface, for example by 3D printing