Source: https://patents.justia.com/patent/20110096570
Timestamp: 2019-08-18 18:58:53
Document Index: 459019301

Matched Legal Cases: ['art 1250', 'art 1250', 'art 1250', 'art 1250', 'art 1250', 'art 1250', 'art 1250']

US Patent Application for ILLUMINATION DEVICE COMPRISING A LIGHT GUIDE Patent Application (Application #20110096570 issued April 28, 2011) - Justia Patents Search
Justia Patents Light GuideUS Patent Application for ILLUMINATION DEVICE COMPRISING A LIGHT GUIDE Patent Application (Application #20110096570)
May 25, 2009 - KONINKLIJKE PHILIPS ELECTRONICS N.V.
FIGS. 1a-1d schematically depict some principles of embodiments of the light guide;
FIGS. 2a-2d schematically depict embodiments of the light guide;
FIGS. 3a-3e schematically depict embodiments of the light guide collimator construction; and
FIGS. 4a-4j show comparative examples of the collimation effects of the grooves comprised by the light guide.
FIGS. 1a-1c schematically depicts an illumination device 1 arranged to generate device light 211. The illumination device 1 comprising a lighting unit, indicated with reference 2. The lighting unit 2, comprises a light source 100, arranged to generate light source light 111, and a substantially flat light guide 200, arranged to collimate the light source light 111 and provide the device light 211.
This optical axis O is especially in a plane substantially parallel to the top light guide surface 201 and/or bottom light guide surface 202: The optical axis O partly coincides with a (virtual) plane parallel with the xy-plane and is also parallel to this plane parallel with the xy-plane (this plane is indicated in FIGS. 2a and 2b). The xy-plane can further be defined as a plane substantially parallel to the top face 201 and/or the bottom face 202. As mentioned above, the top and bottom faces 201,202 are (substantially) parallel in preferred embodiments. Hence, the xy-plane is (substantially) parallel to the top face 201 and bottom face 202. The optical axis O is parallel to this plane and coincides with this plane parallel with the xy-plane.
FIG. 1b schematically depicts the same light guide 200 as schematically depicted in FIG. 1a, but now in top view. Hence, in this schematically depicted embodiment and in this view, L1 and L2 are substantially equal, and W1 and W2 are substantially equal.
FIG. 1c schematically depicts the same light guide 200 as schematically depicted in FIG. 1a, but now in side view. Hence, in this schematically depicted embodiment and in this view, h1 and h2 are equal, and L1 and L2 are equal.
FIG. 1d schematically depicts an embodiment of the lighting unit 2 with light guide 200, which is substantially the same as the embodiments schematically depicted in FIGS. 1a-1c, with the exception that the edge window 220 is slanted. Such slanted edge window is indicated with reference 221. The edge window 220 may for instance have a slant angle β relative to the top light guide surface 201 or the bottom light guide surface 202 in the range of 35-105°. In FIG. 1d, the slant angle β is indicated relative to bottom face 202, and has a value of about 45°. In FIGS. 1a-1c the edge window is not “slanted”, and the “slant angle β” is about 90°. By using a slant angle, especially in the range of about 35-55°, collimated light source light may escape from the light guide 200 via one of the bottom and top surfaces 201,202 as device light 211. Depending upon the shape of the edge window 220 (slanted, V-shape (“double slanted”), curved), the collimated light source light may escape from the light guide 200 as device light 211 via one or both of the bottom and top surfaces 201,202.
These grooves 300 are for the sake of simplicity not drawn in the above schematic drawings. Having however described the lighting unit 2, and especially the light guide 200, in FIGS. 1a-1d, in the next figures, the arrangement of the grooves is schematically depicted and below further elucidated in more detail. FIGS. 2a-2d schematically depict embodiments of grooves 300 comprised by the top or bottom surfaces 201,202.
FIGS. 2a-2d schematically depict embodiments of the light guide 200 having a plurality of grooves 300 comprised by the top and/or bottom light guide surfaces 201,202, respectively. For the sake of clarity, the side edges 230,240 do not comprise grooves 300, but of course, in a further embodiment, grooves 300 may also be comprised by one or more of these side edges 230,240.
The top and bottom light guide surfaces 201,202 having grooves 300 are indicated with references 251 and 252, respectively. FIGS. 2a and 2b schematically depict top views, and (thus) show top light guide surface 201, here with grooves 300, thus also indicated with reference 251. However, these schematic pictures might correspondingly also schematically depict bottom light guide surface 202 comprising grooves 300, thus to be indicated with reference 252. FIG. 2d schematically shows a front view of the edge window 220 of an embodiment of the light guide 200; in this figure it is schematically depicted that both top and bottom light guide surfaces 201,202 having grooves 300.
The grooves 300 have again longitudinal axes 301 along or in the direction of the groove 300 with groove direction angle w with the optical axis O. Each groove 300 may independently have a longitudinal axis 301 having a groove direction angle w with the optical axis O≧0° and <90°. The virtual convergence point P may be arranged behind (i.e. upstream from) the light source 100 (see FIG. 2b), before the light source 100, or at the light source 100 (FIG. 2a). In principle, the grooves 300 of one or more of the top light guide surface 201, the bottom light guide surface 202, the first side edge 230 and the second side edge 240, may converge at different positions P. In FIGS. 2a-2c, the arrangement of the grooves 300 is a radial arrangement, wherein the centre of the circle is at convergence point P.
In a preferred embodiment, especially in a radial arrangement of the grooves 300 comprised by the top light guide surface 201 and/or the bottom light guide surface 202 (see FIG. 2a-2c), such surface comprises at least 1 groove 300 per 10° light guide azimuth angle, especially in the range of about 1-5 grooves 300 per 10° light guide azimuth angle (in the very schematic drawing 2c, by way of example 8 grooves 300 per 180° azimuth angle are depicted). In these embodiments, with radially arranged grooves 300, the groove angle w varies over the top and/or bottom surfaces 201, 202, respectively. This is indicated in FIGS. 2a-2c with ω, ω′, ω″, etc.
FIGS. 3a-3b (inside view) schematically depict wave guides into which light is coupled. The waveguides are indicated with reference 1000. Wave guides are often provided with a low-index layer or cladding (cladding is indicated with reference 1010) in order to avoid light leakage caused by dust or scratches. The basic idea is that light does not enter the low-index layer due to total internal reflection at the light guide—cladding interface. Consequently, scratches or dust at the cladding surface have no effect on the light. For the cladding 1010 to work properly, the light preferably has a large incidence angle onto the cladding, i.e. the light from light source 100 should preferably be sufficiently collimated in the direction perpendicular to the cladding. See FIG. 3a for an illustration of a conventional system with cladding 1010, in which not-collimated light may enter the cladding layer. FIG. 3b shows a conventional tapered collimator 200 at the entrance of the light guide 1000 to avoid light entering the cladding layer 1010. For thin light guide systems, it is usually complicated to collimate light in the conventional way, i.e. by a tapered collimator (see FIG. 3b).
However, the flat collimators 200 proposed in the present invention are very well suited for this: the flat collimator 200 based on diverging grooves 300 (see FIGS. 2a-2d) can collimate light 111 in the direction perpendicular to the light guide 200. This is schematically depicted in FIG. 3c (side view). In FIG. 3c, schematically an embodiment of the light guide collimator construction 1200 is depicted, wherein the light guide 200 is arranged to collimate light source light 111 of the light source 100 and to provide collimated light 211 (not depicted) to the waveguide 1000, wherein the waveguide 1000 may comprises the cladding 1010 having a low-index of refraction (i.e. lower than of the waveguide 1000).
FIG. 3d (side view) schematically depicts a light guide collimator construction 1200 comprising the light guide 200 and a light guide funnel part 1250. The light guide 200 is arranged to collimate light source light 111 of the light source 100 (not depicted) and to provide collimated light 211 to the light guide funnel part 1250. The funnel part 1250 may be an integral part of the light guide 200, but in principle, the funnel part 1250 may also be remote from the light guide 200. The funnel part 1250 can be seen as transition part, allowing narrowing down the height of the device. Here, it is shown that the light guide has height h1, which is smaller than height h4 of the waveguide 1000, in which the light 211 is coupled. The funnel part 1250 has a varying height h3, especially gradually decreasing from height h1 to height h4. FIG. 3d shows the light guide collimator construction 1200 further comprising the waveguide 1000, wherein the light guide 200 and the light guide funnel part 1250 are arranged to provide collimated light 211 to the waveguide 1000.
FIG. 3e (side view) schematically depicts the light guide collimator construction 1200 per se (i.e. a “coupler”), having light construction edge window 1220, which may substantially have the same properties and embodiments as described above with respect to the edge window 220. Such device may be used as “coupler” between the light source 100 and the waveguide 1000.
In FIGS. 3d and 3e, embodiments of the light guide collimator construction 1200 are depicted, where the collimator has collimator height h1 and the waveguide has waveguide height h4, and wherein the waveguide height h4 is smaller than the collimator height h1, such as for instance h1/h4≦2, or ≦4.
Comparative examples have been performed, with a 1*1 mm Lambertian emitter light source (1 lm) and a light guide of 4 mm thickness. In the table below, and in the accompanying drawings 4a-4j, the outcome of these examples is summarized and depicted, respectively. In these drawings, axes ranging from 0-360, are the x-axis of the luminous intensity plots (candela on y-axes) related to the longitudinal luminous intensity of the device light 211, varying from 0-360°; axes ranging from 0-180, are the y-axis of the luminous intensity plots (candela on x-axes) related to the latitude luminous intensity of the device light 211, varying from 0-180°. These plots are lines plots of the beam cross-section of the light (i.e. beam) escaping from the light guide as device light 211.
Longitudinal Latitude Collimator Top/bottom surface FWHM FWHM Example shape grooves width width
1 light guide no no 2*58° 2*58° (comp.) 4*40*40 mm1 (FIG. 4a) (FIG. 4b) 2 Collimator shape yes no 2*41° 2*58° (comp.) (50° diverging side (FIG. 4c) (FIG. 4d) edges 230, 240) (light guide azimuth angle = 2*25°) 3 light guide no yes (diverging 2*42° 2*6° 4*40*40 mm1; grooves; see FIG. 2a; (FIG. 4e) (FIG. 4f) both surfaces) 4 light guide no yes (diverging 2*40° 2*24° 4*40*40 mm1 grooves divergence (FIG. 4g) (FIG. 4h) position P 1 cm behind light source 100; see FIG. 2b; both surfaces) 5 light guide no yes; both surfaces, but 2*57° 2*47° 4*40*40 mm1 grooves are oriented (FIG. 4i) (FIG. 4j) parallel (i.e. ω = 0°) 1Height h1 (=h2) * length L1(=L2) * width W1(=W2); this applies for all examples, except for example 2, wherein W1 < W2 (i.e. diverging from entrance window to edge window).
1. An illumination device arranged to generate illumination device light, the illumination device comprising a lighting unit (2), the lighting unit (2) comprising: wherein the entrance window is arranged to receive the light source light of the light source, wherein the edge window is arranged to allow the collimated light source light escape from the light guide as illumination device light, wherein one or more of the first light guide surface and the second light guide surface comprise a plurality of grooves, and wherein the grooves are arranged to diverge in a direction from the entrance window to the edge window.
a substantially flat light guide, arranged to collimate the light source light, the light guide having: an entrance window and an edge window, a first light guide surface and a second light guide surface, which are arranged substantially parallel, a first side edge and a second side edge, wherein the first side edge and the second side edge are arranged not to diverge or converge from the entrance window in the direction of the edge window, and
9. A substantially flat light guide, arranged to collimate light source light of a light source, the light guide having: wherein the entrance window is arranged to receive the light source light of the light source, wherein the edge window is arranged to allow the collimated light source light escape from the light guide as illumination device light, wherein one or more of the first light guide surface and the second light guide surface comprise a plurality of grooves, and wherein the grooves are arranged to diverge in a direction from the entrance window to the edge window.
Publication number: 20110096570
Patent Grant number: 8292467
Inventors: Michel Cornelis Josephus Marie Vissenberg (Eindhoven), Anthonie Hendrik Bergman (Eindhoven), Tim Dekker (Eindhoven), Giovanni Cennini (Eindhoven)
Application Number: 12/993,283