NL2012379B1

NL2012379B1 - Light device.

Info

Publication number: NL2012379B1
Application number: NL2012379A
Authority: NL
Inventors: Honold Jürgen
Original assignee: Seaborough Ip V B V
Priority date: 2014-03-06
Filing date: 2014-03-06
Publication date: 2015-12-03
Also published as: WO2015133905A1; NL2012379A

Description

LIGHT DEVICE

The present application relates to light devices. In particular embodiments, a light device, comprises: - an elongate and preferably tubular body having at least one open end and a diffusion, scattering or phosphoric layer to emit light out of the body after being impinged by light propagating in and through the body; and - an end cap arranged on the end of the body and carrying at least one light source to emit light into the body.

Such preferably tubular light devices are generally known. Embodiments of the present disclosure have for an object to provide improved light devices, which improvements may relate to one or more than one aspect thereof. For instance, more easy assembly is desired, in particular but not exclusively of end caps in or on the at least one end of the elongate body, as this is cumbersome in many prior art light devices. Moreover, optimum light emission in all directions is desired, where many prior art light devices fail to sufficiently provide all round light emission, as well as homogenous light emission along the length of tubular or otherwise shaped elongate bodies of such prior art light devices.

Many prior art light devices exhibit considerable heat development at extremities of bodies or tubes, in particular at the end caps. To handle the generated heat, many prior art end caps comprise a heat sink or the like, contributing to complexity of assembly, and preproduction of such end caps. Even though such heat development can be addressed through such measures, requirements with respect to heat discharge and transfer also applied to materials used for the bodies or tubes in terms of the thickness thereof or the like, where thicker bodies or tubes have a detrimental effect on cost prices.

Embodiments of the present disclosure present potential solutions to the problems and disadvantages of prior art light devices, to remedy or at least alleviate such problems and disadvantages, to which end the additional features are provided of : - optics near the open end of the body, and arranged in or on the end cap or in or on the at least one light source, - wherein the optics is designed to direct light, emitted by the at least one light source, into the body to directly impinge in a substantially evenly distributed manner on the diffusion, scattering or phosphoric layer.

Providing optics in, on or at an end cap or in or on light sources would not be a logical choice for the skilled person in view of the desire to keep their end caps as simple as possible, to allow for easy assembly. Consequently, this part of the proposed solution to the post-problem of prior art light devices runs against the skilled person's instincts. However, as a further feature contributing to a solution for the prior art problems and disadvantages, the optics is designed to direct light from the at least one light source to impinge directly and preferably distributed as evenly as possible on the body or tube, to minimise losses and optimise efficiency of light and preferably distribute light as evenly as possible over the (inner) surface of the elongate and preferably tubular body to achieve a light output that is also as homogenous as possible over the length of the elongate body, while avoiding higher concentrations of light output near the ends of the body or the endcaps at the ends of the body. In combination, the features distinguishing embodiments of the present disclosure over the prior art contribute to improved light distribution to be more homogenous over the length of the tube or elongate other body, whilst keeping heat development reduced in specific embodiments relying on light conversion, for instance on the basis of phosphorous response to impinging light. Moreover, with a view of keeping end caps as small as possible, the feature of incorporating optics therein, in combination with the light sources, runs contrary to the skilled person's logical anticipation of a potential solution.

Preferred embodiments of the present disclosure can exhibit the feature, that the optics are designed to direct light emitted by the at least one light source to directly impinge on the diffusion, scattering or phosphoric layer at a distance from the end cap. In particular, though not exclusively, in combination with heat generating conversion of impinging light into emittable light, for example based on phosphoric response, this feature has for an effect that the material of the tube or body can be made very thin and still dissipate sufficient heat by the elongate body or tube, without a need for a heat sink or the like in the end cap. Consequently, the end caps can be reduced in size, or accommodate more optics and/or more light sources and/or illuminating power and/or omit (more of the) heat dissipating means, such as a heat sink and/or cooling fins. In a more particular embodiment, the distance can be defined in more detail as the distance from the end cap, where the first light emitted by the at least one light source impinges on the diffusion, scattering or phosphoric layer, which is defined to be larger or more than one centimetre, preferably more than two centimetres and even more preferably in a range between 2,5 and 5 centimetres, and most preferably in case of for instance an elongate tubular body, that is comparable in length with a fluorescent lamp, approximately 3 centimetres. It should be noted, that scattered or diffuse light, which is not in a main or central beam angel originating from the light sources, is anticipated to be sufficient to excite phosphor or initiate scattering or diffusion in a region closer to the end cap than beyond that distance, where direct impingement is effected. For example, it is to be expected that using optics, a part of the light from the LED's and the optics will scatter. Thus, surprisingly, use of even relatively very simple optics has a beneficial effect that scattered or diffuse light from the LED's is used to light up for instance the first three centimetres of a tube. Even in case of more complex optics approximately 10% or less of the total amount of light generated by the LED's can be scattered used to light up the first part of the tube, of for instance the first 3 centimetres. Thus, although relatively simple optics may already provide a means to the ends of the present invention, care should be taken to limit the amount of scattered light to avoid that the first part or length of the lighting device is unevenly lit in comparison with other parts along the length of the lighting device.

In a further embodiment, as an alternative for or in addition to above preferred embodiments, a light device can exhibit the feature that the at least one light source comprise at least one LED light source. Such an LED light source can produce blue light or ultraviolet light, which can be generated in a very cost and energy efficient manner, and still suffice to excite phosphor into generating emittable light.

In a further embodiment, as an alternative for or in addition to above preferred embodiments, a light device can exhibit the feature that the at least one light source comprise five light sources. Any other number of light sources is also possible, for instance two, three or four, or six or more.

However, in particular a combination of five light sources lends itself very well to combination, if desired, with a multiplexer. However, multiplexing can be effected very usefully, in particular a voltage regulated multiplexer, to drive as few as at least two light sources, where each light source may represent one channel (or several light sources may represent one channel) of the multiplexer, wherein each one light source can further be a multiple LED. However, currently commercially available multiplexers are very suitable for four to six channels, and the above mentioned exemplary number of five channels may be extended down to at least two channels. By the use of a multiplexer, it has become possible to employ higher-voltage LED's, when connected to the multi-channel multiplexer, which allows drive of selected ones or groups or the total number of such LED's, to improve Power Factor and Light Flicker, because the current will follow relatively evenly the voltage. Also system complexity of the electronic system/driver of the lamp will be reduced, since these may be implemented in a small IC-solution. In a further embodiment, as an alternative for or in addition to above preferred embodiments, a light device can exhibit the feature that the optics is designed to generate at least one batwing shaped light distribution profile. An alternative definition of the shape from the light distribution profile could be centre symmetrical "heart-shaped". Either of these two indications or an alternative therefore is intended to indicate that light propagating along a central longitudinal axis of the body or tube should be less than light oriented at the wall of the body or tube, so that direct impingement of light and by this evenly distributed impingement and for example associated activation of the phosphor and therefore even light output and heat distribution on the body or tube can be achieved. In such an embodiment, a further feature can be that the optics are designed to generate multiple overlapping and complementary batwing or heart shaped profiles, which illuminate different and/or potentially overlapping regions of the body along the length thereof. For such an embodiment, preferably, individual light sources can be provided with a corresponding optics per light source, in order to establish the regions or ranges where light from the distinct light sources is to impinge on the body or tube, for instance to excite phosphor evenly along the length of the body or tube.

In a further embodiment, as an alternative for or in addition to above preferred embodiments, a light device can exhibit the feature that the optics are arranged immediately on or against the at least one light source. The optics may even be formed by primary optics integrated into or forming a part of the LED's. This feature includes the possible embodiment that several light sources are combined with a single optics element, to establish a very elongate batwing profile or heart shaped profile, or alternatively still provide separate ranges or regions where light from separate sources is to impinge on the body or tube.

In a further embodiment, as an alternative for or in addition to above preferred embodiments, a light device can exhibit the feature that the diffusion layer comprises phosphor.

It should be noted that embodiments of the present disclosure can have a phosphor layer, wherein light can be generated on the basis of impinging other light, as a diffusion layer, for one of a common, more general indication to encompass diffusion, phosphoric responses, scattering and the like.

In a further embodiment, as an alternative for or in addition to above preferred embodiments, a light device can exhibit the feature that the light sources in operation emit blue light, UV light or near UV light. As previously indicated, blue and/or UV light can be generated at low energy cost and relatively easily. LED's for generating blue, near-UV and UV light in fact do contribute to the generation of heat in the end caps. Further, in particular the feature of distance between the light sources and up to where the body or tube is directly impinged (within a primary beam angle), heat development in the end cap and/or in the direct vicinity thereof may be minimized. In fact, a considerable portion (50 - 80%) of heat generated in light devices having a UV light source and phosphor layer inside the body is generated by LED's. The remainder of heat generated by these potential embodiments of light devices according to the invention is generated by the phosphor layer. By separating these distinct causes of heat generation over a distance, heat generation at the end caps is at least reduced. Consequently, design requirements with respect to handling such heat can be reduced correspondingly, in particular if the material of the body is capable of discharging the heat generated by the layer.

Moreover, as a rule of thumb, it is noted that when light is converted from short, high-energy wavelengths, such as blue and UV, into longer wavelengths, such as yellow, green and red, the resulting spectrum is assembled from the exciting and the excited light. In case of lighting devices, the resulting spectrum is normally desired to be as white as possible, but in the present disclosure other colours are not to be excluded. Further, when using LED's as light sources, it is preferable to use simple LED's and/or LED's that are designed to emit a light beam of a single wavelength (monochrome) or a light beam of wavelengths within a small range or band, for example 380 - 475 nm. As used LED's may be very simple, these can be obtained at very little cost. State of the art LEDs with a peak-wavelength of 450-470nm are very common, highly efficient and are mass produced, so these LED's are available against very low costs. UV-LED supply and use at approximately 380-420nm is increasing because of their lower "droop-effect", so it's foreseeable that also these wavelength-range could be used in the future for embodiments of and/or in the present disclosure. Lower droop effect means that the efficiency of the LEDs doesn't drop as much as normally when the current that passes through them is increased.

Embodiments of the present disclosure are above indicated in general terms, corresponding with the features defined in the appended set of claims. Below, more detailed embodiments will be described, referring to the appended drawings, where specific features, effects, components and aspects are presented merely by way of example, to which the scope of protection for the disclosed embodiments in the claims is by no means to be limited. In the drawings the same features, aspects, components and elements may be designated using the same reference numerals, and: FIG. 1 shows a potential embodiment of the present disclosure; FIG. 2 shows a potential embodiment of the present disclosure; FIG. 3 exemplifies the difference between light distribution according to embodiments of the present disclosure relative to prior art light devices; FIG.'s 4 and 5 present further features of prior art light devices; FIG.'s 6 and 7 exhibit a phosphor layer based mechanism of generating emittable light; FIG.'s 8 and 9 exemplifies separate embodiments of the present disclosure; FIG.'s 10 - 12 exemplify an embodiment of the present disclosure, based on primary LED lenses/optics, and showing multiple overlapping and complementary heart shaped beams; FIG.'s 13 - 14 exemplify a single embodiment of the present disclosure, based on Mini TIR lenses; FIG.'s 15 - 16 exemplifies a single embodiment of the present disclosure, based on a TIR lens accommodating a single high power LED source; FIG. 17 exemplifies a light profile obtainable with an embodiment like the one of FIG.'s 15-16 or an alternative embodiment; FIG.'s 18 - 19 exemplify a single embodiment of the present disclosure, based on a common Multi-TIR lens accommodating a plurality of LED sources; FIG. 20 exemplifies a combined embodiment comprising a Multi-TIR lens as in FIG.'s 18, 19 and a additional optic elements thereon; FIG.'s 21 - 22 exemplify a single embodiment of the present disclosure, based on a Fresnel lens accommodating a plurality of LED sources; FIG.'s 23 - 24 exemplify a single embodiment of the present disclosure, based on a freeform silicon lens accommodating a plurality of LED sources; FIG.'s 25 - 27 exemplify a single embodiment of the present disclosure, based on a combination of primary optics of different types accommodating a plurality of LED sources; FIG.'s 28, 29 exemplify a single embodiment of the present disclosure, based on a silicon ball inserted into a tube or body of a light device; FIG.'s 30, 31 and 32 exhibit exemplary characteristic graphs of light emitted by each one of several phosphor-materials, when light from a LED source impinges thereon having a wavelength of 455 nm; and FIG. 33 exhibits a graph of a heart or batwing shaped light distribution graph setting out intensity against direction, to clarify the disclosure of FIG. 3 and other figures showing or referring to the heart or batwing shape.

General idea of lighting the tube

This below description will refer - by way of example - to different optic(s)/LED setups in light devices like the lamp 1 in FIG. 1, that are integrated in a transparent tube 3 equipped with a remote phosphor layer 6 or tube. The expression that the phosphor layer 6 or tube is "remote" is intended to signify that the light from a source 5 or sources needs to impinge thereon also at considerable distances from the source 5 or sources. However, the phosphor layer 6 is also provided relatively close to the light source 5 or sources.

The phosphor layer can be arranged in any known or new manner. For example reference is made here to a process of up-flushing, which is known to be used for applying a cover layer or coat of phosphor on the inside of a glass or polycarbonate tube.

Glass tubes exhibit advantages in that heat conduction and dissipation thereby are presently higher than that of plastics, glass can be manufactured very economically, and expansion of glass against in temperature variations is minimal compared with plastics, like polycarbonate. Nevertheless, plastics like polycarbonate are by no means excluded from embodiments according to the present disclosure.

Upflushed phosphor material may have also a further advantage compared to a layer of phosphor embodied in a plastic. Extruded phosphor-plastic will have an even, glare surface where light will bounce off, especially when hitting the surface in a stall angel. In contrast a microstructure of upflushed phosphor is anticipated to exhibit a more rough surface where the light will not bounce off. Consequently a higher ration of the blue/UV light can enter the phosphor without bouncing in first place, and more of the radiant power will be converted. The UV/blue-light left after going through the phosphor will be partly bouncing off the inner surface of the glass tube because of the stall angel, entering the phosphor again, therefore, this choice of carrier material of phosphor + carrier material of the phosphor layer (tube body glass) is expected to work best, where a UV/blue monochrome wavelength is hitting the phosphor in a stall angel.

The objective of converting most of the excitation spectrum into the white light spectrum that then will radiate in all three dimensions can thereby be better achieved, in particular for even light-distribution in a room, where the lamp is installed, or for even light distribution of the lamp in general or total (regardless of the room), as the light is not influenced by the fact that the light source is only arranged in the end caps.

Figures 30, 31, and 32 exhibit responses of several materials to blue light from a LED based on InGaN. Any of these materials Lu3A150i2 : Ce (1% ) , Lu3A150i2 : Ce (1%) + CaS:Eu(Si02) and Lu3A15012 : Ce (1%) + Sr2Si5N8:Eu, or any other suitable material may be arranged in a coat or cover on the inside of a glass or other tube in combination with LED light sources, to generate white light or light of any suitable and/or desired colour.

Other mechanisms than phosphor for emitting light out of the body shaped in these embodiments as a tube, are by no means excluded, such as scattering, diffusion and the like, provided the light source 5 or sources generate light with sufficient intensity, to be emitted out of the body or tube 3 and provide sufficient light to fulfil a desired function for lighting.

The tube 3 is closed with end caps 2 containing driving circuitry 4 and end caps 3 are equipped with for example UV LED's 5 forming the light sources 5 that are placed in and more particularly on both of the end caps 2 on the tube 3 of the light device 1. Alternatively, blue or near-UV LED's may be employed. Since the remote phosphor 6 will be activated by UV light (or blue or near-UV light) hitting its surface, the key objective is to create an even spread or distribution of light (360 deg.) throughout the phosphoric surfaces 6 of the tube 3, similar to the lighting behaviour of a generic fluorescent tube (not shown).

When placing LEDs 5 in the end caps 2 of the light device 1, the general lighting pattern will, without further measures / features, be balloon shaped as indicated with the balloon 7 exhibited in FIG. 1. Such a shape is generally normally referred to a lambertian radiator, resulting from a simple primary lens with no explicit function of shaping the light radiated by the LED, although herein below reference may be made to a balloon shape .

As can be noticed, most of the light will be concentrated in the outer regions of the tube. This will cause an uneven spread of light throughout the whole tube. Moreover, much of the light generated by the LED's 5 is directed longitudinally relative to the elongate shape of the tube 3.

To address this, in the light device 10 of FIG. 2 having end caps 12 accommodating drive circuitry 14 with electrical contact pins 11 and LED's 15, and a tube 13 carrying a phosphor layer 16, optics 18 are provided in or on the end caps 12 or even on LED's 15 to direct the light from the LED's 15 to where light it is needed most, as indicated in FIG. 3, exhibiting a comparison of the spread in intensity without optics (Lambertian or balloon shape 7) as in FIG. 1, and a potentially achievable spread in intensity using optics as shown by way of example in FIG. 2.

Adding optics 18 over the LEDs 15 will result in more focussed beam patterns 19, 20 that can light the tube 16 more evenly, as is evident from the supplementary, augmenting or complementary 3-Dimensional heart shaped or batwing shaped forms 19, 20 of light distribution, also in FIG. 3. This shape is referred to as a batwing shape in side view, and is more explicitly depicted in an exemplary embodiment in FIG. 33. The actual shape is 3-Dimensional in that the side view shape is line symmetrical for rotation around the central axis of the shape, which coincides with or is parallel to the longitudinal axis of the tube 3. Below it will be clarified there are many alternatives for the optics 18 exemplified in FIG. 3 to be Mini TIR lenses 18.

Benefits of using phosphor light spreader

As exhibited in FIG.'s 4 and 5, when using white LED's 5 to light up a tube 3 without a phosphorous or phosphoric layer 16, rays 8 of light will have to travel through the material of the tube 3 over long distances dl in FIG. 5, after the beams 8 impinge on the surface of the material of the tube 2 at steep angles, as can be seen in FIG.s 4 and 5.

With the phosphor layer 16 in FIG.'s 6 and 7, light beam 22 of blue light (see below) impinging on the phosphor layer 16 in FIG. 2, 6 and 7 will at least partly be converted into broad bandwidth (white) visible light 21 by the phosphor layer 16. This converted light 21 will scatter in all directions, as shown in FIG.'s 6 and 7. A similar effect of avoiding the long path through material of the tube 13 can be achieved using an alternative scattering or diffusing layer.

Residual reflected blue light beam 23 will continue in the tube 13 to impinge on phosphor further down into the tube 13, and generate white light there. White light 24 from the phosphor layer 16, directed into the tube 13, will emit out of the tube 12 or will also impinge on phosphor layer 16 opposite to the location where the white light 21, 24 was generated by the phosphor, to also generate a reaction from the phosphor layer 16 and generate more white light 25.

Since the conversion reaction within phosphor decreases the distance that light will have to travel through the material of the tube 13, remote phosphor systems can be much more efficient than non-phosphoric systems.

Light that is scattered outwards is direct useful light.

Light that is reflected 23 or scattered 24 back into the tube will cause another conversion reaction 25 in other areas of the tube 13. This is also the case for light 23 that is directly reflected off the phosphoric layer. This light will travel through the tube until it hits the tube wall in another spot 26 and cause a conversion reaction there.

Below several optic systems are presented that can be employed in embodiments, for example in conjunction with the above described phosphoric layer based tubular light device.

Below, manners of distributing the light effectively along the tube's inner phosphoric layer are disclosed, but it should be emphasized that the herein disclosed configurations lend themselves very well to useful application in the framework of other mechanisms than phosphor based light generation, such as diffusion or scattering based light devices.

Optical properties

Optic configurations disclosed below and shown in appended drawings each exhibit their own specific way of lighting the tube efficiently. A common but not limiting feature of the embodiments in the following description is that a first part, for example over a distance of preferable 30 mm from the end caps with the LED's, of the tube immediately next to the LED's or 15 other light sources is not illuminated directly, as depicted with d2 in FIG. 8. There with it is possible to employ primary optics or for example mini TIR lenses 27 as secondary optics and d3 in FIG. 9, employing for example a TIR, Multi TIR, Fresnel or Freeform silicon lens 28 as secondary optics. A distance d2, d3 from the end cap 14, over which light emitted by the at least one light source 15 impinges on the diffusion, scattering or phosphoric layer 16 in the tube 13, is -if such a distance is embodied - more than one centimetre, preferably more than two centimetres and even more preferably in a range between 2,5 and 5 centimetres, and most preferably in case of for instance an elongate tubular body comparable in length with a fluorescent lamp approximately 3 centimetres.

Since 10 - 20% of the light (or less or more thereof) in an optic system is not maintained within the beam angle, but distributed or scattered diffusely, this diffuse light (not indicated in the figures, but inherently present) will impinge on the tube closer to the end cap(s) 12 for illuminating the extremities of the tubes.

Especially in combination with the use of a phosphoric layer 16, excited through impinging light from at least one source 15, such as at least one LED source 15, to generate light emission from the tube shaped embodiment of an elongate body, the excitation of the phosphor in layer 16 and resulting conversion of light encompassing all wavelengths to generate (more or less) white light therein is known to generate considerable amounts of heat. This mechanism accounts for 15-30% of the total heat generated by the light device, but the actual percentage may vary with or depending on the color temperature: higher Color themperatur will require less phosphor/conversion, leading to less losses in the conversion process. Thus, heat of the conversion process may be summarized to amount to about 15% at approximately 6000K, compared to about 30% at approximately 2700K.

The feature and effect of directing the beam angle such as to impinge on the phosphoric layer only at a (considerable) distance from the end cap(s) 12 safeguards the end caps 12 and the ends of the tube near the end caps 12 from being subjected to excessive amounts of heat resulting from light conversion, but in the end cap(s) heat is still generated by the LED's. Nonetheless, this feature already allows for countermeasures, such as heat sinks and the like, to be omitted or at least decreased by employing smaller heat sinks, cooling fins or the like, or allow for more light output / more LED's, et cetera. It is however noted that in view of heat generating aspects this feature may be employed, but for scattering or diffusion based devices these consideration may be less important and the beam angle of at least one combination of a LED and corresponding optics can then be wider to allow light to impinge directly from the LED's 15 on a scattering or diffusing layer of the tube 13 closer to the end caps 12. By purposefully directing a main beam angle such, that a direct beam impinges on the interior of the body only at a considerably distance from the end cap(s), account is cleverly taken of the fact that scattered light from the light sources, the optics or from the environment will still suffice to excite the phosphor closer to the end caps than the borders of the main beam angle .

Optic systems

Several embodiments of optic systems have been developed to produce light patterns that are expected to satisfy the requirements as described above. The follow types of optic systems have been developed within the framework of and bounds according to the appended claims, and will be explained below: - Primary optic - Secondary optics o TIR (= total inner reflection) o Mini TIR o Multi TIR (dome) o Fresnel o Freeform silicon lens - multiple-stage systems Primary optics of LED's A possible embodiment for distributing light 22 in a correct way as indicated by profiles 19, 20 in FIG.'s 3, 12 is by using the primary optics of the LED's itself.

Every one of the LED's 15 is assigned with its own specific area that needs to be lighted along the length of the tube 13. Therefore, every optic for each LED needs to be correspondingly designed. In order to maximize the light output of the tube, the shape 28 of lenses of the LED's 15 themselves may be designed to resemble a 'donut' shape (FIG.'s 10 and 11). By using this donut shape 28, the lenses of LED's 15 generate centre symmetrical, revolved batwing or heart shaped beams, as depicted in FIG. 12.

The batwing shaped separate beams 19 - 20 in FIG. 12 can be generated by different lenses 28, one for each of the five LED light sources 15, combined with the corresponding one of the LED's 15. Each LED 15 has a lens therewith to achieve for each LED separately a different profile length 19 - 20. As such, FIG. 12 substantiates how the different embodiments of lenses can adapt the light beam profile of the corresponding light source in correspondence with and depending on a length of the tube 13 forming the body of the light device.

In this manner light output on the sides (walls) of the tube 13 is increased, while less light is directed to the centre regions of the tube along the centre axis thereof, as light 22 passing along this centre axis will not be converted by the phosphor. This is to say that a parallel beam along a longitudinal axis of the tube 13 is less desired and beam components along that axis are attenuated through the use of the above referred to lenses 28 of the LED's 15, which result in the batwing shaped beams exhibited in FIG. 12. It is noted here that such batwing beams 19 - 20 are also useful in light devices based on other light sources than LED's, and light generating or distributing or diffusing or scattering mechanisms, like scattering or diffusing surfaces on or in the tube forming the body of the light device, et cetera.

It is further noted that in the embodiment of FIG. 10, multiplex connectors 65 are shown, for four channels and an additional connector. The use of a multiplexer, for which the connectors 65 are shown, can contribute to lowering heat generation. Such connectors 65 are shown in many of the embodiments in the appended figures, described below, without further detailed attention to these connectors 65 at the location below of description of such other embodiments in the following description Mini TIR lens optics

In the embodiment of FIG. 14, five LED modules 15 are mounted in each of the end caps 12. On top of each of these LED modules 15 sits a small mini TIR lens 29, shown in an enlarged representation in FIG. 13. TIR stands for "Total Inner Reflection". The objective is again to generate multiple (here: five) beams 19 - 20, as shown for instance in FIG. 12, using five LED modules 15 and associated mini TIR lenses 29, one lens 29 for each LED module 15.

Each LED/lens module 15 is responsible for mainly illuminating a designated area of the tube, as represented in FIG. 12. As a result of this custom light distribution per combination of a LED module 15 with a corresponding mini TIR lens 29 arranged on the LED modules 15, each of the TIR lenses 29 is to have a different, tailor made shape, corresponding with one of the five profiles 19 - 20 in FIG. 12. In order to maximize the light output of the tube (light device), all lenses 29 have generally a donut shape, as shown in FIG.'s 13 and 14, which is however different from the donut shape of the LED lens 28 shown in FIG.'s 10 and 11.

By using this shape or a similar shape, the combinations of LED modules 15 and individual corresponding lenses 29 will produce five centre symmetrical batwing shaped beams 19 - 20, as shown in FIG. 12. This lens shape results in high intensity light on the side walls of the tube at different distances along the length of the tube 13, and less intense light in the centre areas (along the longitudinal axis) of the tube, as depicted also in FIG. 12.

The mini TIR lenses 29 have a curved outer surface 30 and depression 31 relative to an upper edge 32, with a wave shaped ridge 33 in the depression 31. In a bottom of the TIR lens 29 a cavity 34 is formed to accommodate or be placed over the LED module 15. TIR lens optics

In the embodiment of FIG.'s 15, 16 a single, relatively large TIR lens 35 is employed in combination with a high power LED module 36. The TIR lens 35 has a straight diverging outer surface 37 and a straight walled depression 38 relative to an upper edge 39, with a wave shaped ridge 40 in the depression 38. In a bottom of the TIR lens 37 a cavity 41 is formed to accommodate or be placed over the LED module 36. The centre of the lens 35 is concavely shaped in order to direct the light outward (FIG. 17), while light that is oriented to exit the side of the lens is redirected in a straight line. This embodiment results in a single large or long, centre symmetrical batwing shaped light beam 42 in FIG. 17 that extends to the longitudinal centre of the tube, as depicted in FIG. 17, or beyond this middle of the tube.

Multi TIR (dome) lens optics

The Multi TIR 43 is comparable with a regular TIR lens of FIG.'s 15 and 16, except for curved outer surface 47 and for an extra ring shaped cavity 44 in the bottom of the Multi TIR lens 43. This extra ring shaped cavity 44 accommodates a circular array of LED's 45 that directly radiates to a planar top section of the lens 43. An inner region of the Multi TIR lens 43 is concavely shaped to achieve a centre symmetrical batwing shaped light pattern in the centre of the tube, comparable with the one of the above described TIR lens 35, as shown in FIG. 17.

Further control over light beams emitted from the Multi TIR lens 43 can be achieved by adding additional optic elements 46 on the Multi TIR lens 43, as shown in FIG. 20.

Fresnel lens optics

When using a Fresnel lens 48 in combination with a circular array of LED's 49, as depicted in FIG.'s 22 and 23, the different rings 50, 51, 52 of the Fresnel lens 48 can be used to direct light to where it is needed, e.g. to achieve the profile as depicted in FIG. 12. In this embodiment, a three ring Fresnel lens 48 is used to create three centre symmetrical batwing beams 53, 54, 55, instead of the five profiles 19 - 20 shown in FIG. 12. A five ring Fresnel lens would result in the profile of FIG. 12. Freeform silicon lens

By using a freeform silicon lens 56, as shown in FIG.'s 23 and 24, a single pre-calculated optic disk 57 can be moulded to comprise separate optics 58 for each of the five LED's 59. This way, every LED 59 can have an individually corresponding optics chamber inside a singular lens 56. With respect to a resulting distribution of light, this configuration means that light can be directed in a similar way as with the primary optics or the mini TIR lenses, described above. In this case however, only one lens 56 with integrated individual lenses 58 for the separate LED's 59 is required to achieve this objective of individual ranges for the separate LED's 59. As the configuration of FIG.'s 23, 24 comprises five LED's, the generated profile is intended to resemble that of FIG. 12.

Multiple-stage systems

Installing any of the lens systems of FIG.'s 13 - 24 on top of the primary lenses of FIG.'s 10 - 12 allows for even more accuracy in beam control, as shown generally in FIG.'s 25 - 27. Since the primary optics in FIG.'s 10 - 12 are already tailored to create centre symmetrical batwing lightbeams, the secondary optics can be designed and employed specifically to direct the light to the areas where (for example in terms of distance from the end caps) it is needed. These secondary optics can be similar to the optic systems that are discussed in the previous sections, e.g. Fresnel lenses (FIG. 21, 22 combined with FIG.'s 10, 11, resulting in configuration of FIG. 27), freeform silicone (FIG.'s 23 and 24 combined with FIG.'s 10, 11, resulting in configurations of FIG.'s 25, 26), miniTIR (FIG.'s 13, 14), or any other additional lens system on the primary lenses (FIG.'s 10 - 12)of the individual LED's .

Silicon ball

Referring to the light device 60 in FIG.'s 27, 28, all lens systems described above are such that most of the light emitted by LED's on end caps 61 is directed to the sides or wall of the tube 62. However, due to reflection and scattering some light will cross (more than) a half of (with opposing end caps) or the entire tube length (in case of a single end cap) without being converted to functional light that is emitted out of the light device's body or tube 62.

Since light that reaches the other side of the tube will hit the opposing end cap and normally be absorbed there, this amount of light will not contribute to additional light.

To prevent light from the (LED) light sources from being wasted in this manner, a reflective or scattering silicon ball 63 can be placed at an end (single cap with LED's) or in the center 64 (in case of opposing end caps) of the tube. This ball 64 is added in addition to the lens optical systems described above, when necessary.

With the ball 63 in place, light that reaches the center 64 of the tube will be reflected back into the tube 62. Because of the spherical shape of the ball 63, reflected light will directed towards the phosphoric layer, as can be seen in FIG.'s 28 and 29. Alternatively, the ball 63, which may be manufactured from silicon, may have a scattering characteristic. Then, light that reaches the centre will be scattered and mainly distributed to the middle of the tube.

Light normally has difficulty reaching the middle of the tube, using optical systems, especially when the tube is very long. Because of this, a light collecting ball that scatters the light mainly towards the middle can be very helpful to reach a even light distribution along the tube.

Alternatively, end caps may have a diffusing, reflective or other layer to prevent light from LED's on an opposing end cap from being absorbed by the end cap on which the light impinges.

Such a ball may be replaced by an upright eye shaped mirror, to achieve the same reflections over a larger length of the tube 62. Other embodiments than those of the preceding description and appended drawing are also possible within the scope of protection as defined in the appended claims. In particular combined embodiments comprising features from separately presented embodiments are possible, as well as alternatives for specific features, unless these alternatives are excluded in accordance with the appended claims defining the scope of protection for the specifically presented and other alternative embodiments.

Claims

A light device, comprising: - an elongated, preferably tubular body with at least one open end and a diffusion or scattering-based or phosphoric layer for emitting light from the body after incident of light propagating into and through the body body; - an end cap which is arranged on the end of the body and carries at least one light source to emit light into the body; and - optics near the open end of the body and arranged in or at the end cap, or in or at the at least one light source, - wherein the optics are configured to direct light from the light source to the body to directly to the diffusion or scattering-based or phosphoric layer in a substantially uniformly distributed manner.

The light device according to claim 1, wherein the optics is configured to direct light from the at least one light source into a main beam angle to directly and preferably as uniformly as possible incident on the diffusion or scattering-based or phosphoric layer on a distance from the end cap.

The light device according to claim 2, wherein the distance from the end cap, where the first light in the main beam angle coming from the at least one light source is incident on the diffusion or scattering or phosphoric layer, is greater than at least one centimeter, is preferably more than two centimeters, and more preferably even in the range between 2.5 and five centimeters, and most preferably, in the case of, for example, an elongated body with a length corresponding to a fluorescent lamp, approximately three centimeters .

The light device according to any of the preceding claims, wherein the at least one light source comprises at least one LED light source.

The light device according to any of the preceding claims, wherein the at least one light source preferably comprises four to six and more preferably at least five light sources.

The light device according to any of the preceding claims, wherein the optics is configured to generate at least one bat or heart-shaped profile of light distribution.

The light device of claim 6, wherein the optics is configured to generate a number of additional, complementary and potentially overlapping bat or heart-shaped profiles of light distribution, illuminating different and / or potentially overlapping regions of the body along its length.

The light device according to any of the preceding claims, wherein the optics are arranged directly on or against the at least one light source, such as primary optics of LED light sources.

The light device according to any of the preceding claims, wherein the layer comprises phosphorus.

The light device according to claim 9, wherein the phosphor comprises at least one of the materials from the group, which comprises: Lu3Al150i2: Ce (1%); Lu3 Al15012: Ce (1%) + CaS: Eu (SiO2); and Lu3Al50i2: Ce (1%) + Sr2Si5N8: Eu, and is configured to be arranged preferably in or on the elongated and preferably tubular body using a so-called upflush process.

The light device according to any of the preceding claims, wherein the operating light sources emit blue light, UV light or near-UV light, preferably located in any of the wave length ranges between 450 nm and 475 nm, and between 380 nm and 420 nm.

The light device according to any of the preceding claims, wherein the end cap comprises a ceramic material as a heat-conducting and electrically insulating material.

The light device according to any of the preceding claims, wherein the end cap comprises a heat-conducting and electrically insulating plastic material.

The light device according to any of the preceding claims, further comprising a multiplexer, which is connected to the light sources for controlling it.

The light device according to any of the preceding claims, wherein the diffusion or scattering based or phosphoric layer of the elongated and preferably tubular body is applied using a so-called upflush process.