ILLUMINATION DEVICE, LUMINAIRE AND REFRIGERATOR

Abstract

The invention relates to an illumination device comprising a domeshaped, cylindrical lens (7) having an optical focal line (19) and a plurality of light sources (3) arranged along the focal line and configured to emit light during operation. Said lens being disposed to receive and to deflect said light as a light beam having an angle y in a transverse direction, wherein 0′<=.sub.7<=30′. In transversal cross section the cylindrical lens comprises a central portion (21) flanked by a first side portion (23) and a second side portion (25). The illumination device further comprises an axially extending screen (27) disposed adjacent to the first side portion; and an axially extending diffuser (33) provided at the second side portion.

Claims

1. Illumination device comprising: a dome-shaped, cylindrical lens having an optical focal line defining a main axis; a plurality of light sources arranged along the main axis and configured to emit light during operation; said lens being disposed to receive and to deflect said light as a light beam having an angle γ at FWHM in a direction transverse to the main axis, wherein preferably 0°<=γ<=45°, in transversal cross section the cylindrical lens comprises a central portion flanked by a first side portion and a second side portion; an axially extending screen disposed adjacent to the first side portion; and an axially extending diffuser provided at the second side portion, wherein the cylindrical lens comprises an inner lens surface facing towards the plurality of light sources and an outer lens surface facing away from the light sources and wherein the diffuser is at least provided on the outer lens surface, wherein the second side portion has an axially extending second outer edge and wherein with respect to rotation over the focal line the diffuser forms a diffuser area which starts at angle φ from said second outer edge, wherein 0°<=φ<=40°, and wherein the diffuser area extends over angle Θ, wherein 5°<=Θ=15°.

2. Illumination device as claimed in claim 1, wherein each of the plurality of light sources is positioned on the focal line and each light source has a respective optical axis extending through the cylindrical lens in a direction transverse to the main axis.

3. Illumination device as claimed in claim 1, wherein with respect to rotation over the focal line, the dome shaped lens extends over the plurality of light sources over angle α, wherein 90°<=α<=160°.

4. Illumination device as claimed in claim 1, wherein the first side portion has an axially extending first outer edge, and wherein with respect to rotation over the focal line the screen screens the dome from the first outer edge over an angle ß, wherein 10°<=ß<=50°.

5. (canceled)

6. Illumination device as claimed in claim 1, wherein 10°<=φ<=30° and wherein 8°<=Θ<=12°.

7. Illumination device as claimed in claim 1, wherein the diffuser comprises at least one of a white powder coating, a white tape, a white spray-coating, a sandblasted and an etched surface structure.

8. Illumination device as claimed in claim 1, wherein the cylindrical lens is an extruded lens and wherein the diffuser is a co-extruded component.

9. Illumination device as claimed in claim 1, further comprising a reflector having a reflective surface facing towards the lens, wherein said reflector is arranged adjacent to the second side portion and wherein the diffuser is additionally provided on said reflective surface.

10. Illumination device as claimed in claim 1, wherein the diffuser is an anisotropic diffuser having a degree of diffusion in the main direction higher than the degree of diffusion in the transverse direction.

11. Illumination device as claimed in claim 1, wherein the diffuser has a beam widening effect of widening the beam by an angle δ, wherein 1°<=δ<=5°.

12. Luminaire comprising a housing accommodating the illumination device as claimed in claim 1 and further comprising fixation means for mounting the luminaire to a carrier.

13. Refrigerator comprising a refrigerator door frame, a refrigerator compartment comprising at least one shelve and lidded by a refrigerator door, wherein the illumination device as claimed in claim 1 and/or the luminaire mounted onto a first vertical post of the door frame for illuminating from a first direction a front part of the shelve closest to the refrigerator door.

14. Refrigerator as claimed in claim 13 comprising a further illumination device or a luminaire mounted onto a second vertical post, opposite to the first vertical post, for illuminating from a second direction, opposite to the first direction, the front part of the shelve closest to the refrigerator door.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The invention will now be further explained by means of the schematic drawings which are not drawn up to scale and in which dimensions of some features may be exaggerated for the sake of explanation. The drawings are by no means intended to limit the scope of the invention but rather are intended to exemplify the ample possibilities of the invention. In the drawings:

[0024] FIGS. 1A-B show the prior art illumination device and its appearance when applied in a refrigerator application;

[0025] FIGS. 2A-B show a first embodiment of an illumination device according to the invention and its appearance when applied in a refrigerator application;

[0026] FIGS. 3A-B respectively show a perspective view and a transversal cross-section of a luminaire comprising a second embodiment of an illumination device according to the invention;

[0027] FIGS. 4A-B show a refrigerator comprising two illumination devices according to the invention, and

[0028] FIG. 5 shows a luminaire comprising an illumination device according to the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0029] FIG. 1A-B show the prior art illumination device 1 and its appearance when applied in a refrigerator application. The illumination device comprises a plurality of light sources 3, in the figure a LED strip which issues light 5, i.e. light source light, with a Lambertian beam profile during operation. A cylindrical lens 7 is mounted over the LED strip. The cylindrical lens has dome shaped transversal cross section and deflects light source light as a (relatively) narrow beam of deflected light 9 from the LED strip towards an object 11. In the FIG. 1A-B the object is merchandise, but the object could, for example, alternatively be a wall, a shelve or a painting. The merchandise illuminated by the light source is visible by a customer 13. However, the customer is also distracted by the light source as because of a negative side-effect of illumination of the merchandise, both the light source itself as well as a reflected image 15 thereof in the lens are visible by the customer. This negative side-effect is shown in FIG. 1B and is often referred to by customers as the “Christmas tree” effect because of its dotty appearance.

[0030] FIG. 2A-B show a first embodiment of an illumination device 1 according to the invention and its appearance when applied in a refrigerator application. The illumination device comprises a plurality of light sources 3 which issues light, i.e. light source light 5, with a Lambertian beam profile during operation. The light source is an axially extending LED strip along a main axis 17 (perpendicular to the paper). An axially extending cylindrical lens 7 is mounted over the LED strip, such that the LED strip is positioned on a focal line 19 of the cylindrical lens, coinciding with the main axis which collimates or deflects the Lambertian beam profile into a deflected light beam 9 having a beam angle γ of about 15° at FWHM. The lens has a central portion 21, flanked by a first side portion 23 and a second side portion 25. In transverse direction the cylindrical lens has a dome shaped cross section extending over an angle α of about 90° over the LED strip, and deflects light source light as a (relatively) narrow beam of deflected light 9 from the LED strip towards merchandise 11. The merchandise illuminated by the light source is visible by a customer 13. A direct view of the light source by customers is blocked by an axially extending screen 27 disposed adjacent to the first side portion of the lens which screen the dome from a first outer edge 29 over an angle ß of about 15°. The cause of glare to a customer by a clear reflected image 15 of the light source (LED die) in the second side portion of the lens is counteracted in that an axially extending diffuser 33, in the figure a white tape, is provided at an outer surface 35 of the lens at the second side portion. The white tape starts from a second outer edge 31 of the lens at an angle φ of about 20° and extends over an angle Θ of about 10°. The angles α, ß, φ, and Θ are all determined with respect to rotation over the focal line. The white tape diffuses a part of the deflected light source light and causes a small beam broadening δ of about 3° (determined with respect to rotation over the white strip). As shown in FIG. 2B, it is thus attained that a more visually attractive continuous light line is formed as a reflected image 15 of the light strip, instead of a distracting visible dotted line.

[0031] FIG. 3A-B respectively show a perspective view and a transversal cross-section of a luminaire 37 comprising a second embodiment of an illumination device 1 according to the invention.

[0032] The luminaire comprises an elongated housing 39 which extends along a main axis 17. The housing accommodates the illumination device and comprises fixation means 41, in the figure mounting ridges, but which alternatively or additionally could be screws, bolts, magnets or snap features. The illumination device comprises an axially extending LED strip 3 arranged on a focal line 19 of an axially extending cylindrical lens 7, dome shaped in a transverse cross section, and extending axially over the LED strip. Viewed in cross section the dome shape extends over an angle α of about 115°, wherein the Lambertian emission profile of the LED is transformed into a deflected beam having a beam angle γ of about 45° at FWHM. The illumination device further comprises an axially extending screen 27 at a first side portion 23 of the cylindrical lens, which screen is an integral part of the housing of the luminaire. The screen screens the cylindrical lens over an angle ß of about 25° of the dome shaped cross section. As an axially extending diffuser 33 the lens comprises at a second side portion 25 at an outer surface 35 thereof facing away from the LED strip, a spray coating. The spray coating starts from the second outer edge 31 of the lens at an angle φ of about 25° and extends over an angle Θ of about 10°.

[0033] FIG. 4A-B show a refrigerator 43 comprising two illumination devices 1 according to the invention. In FIG. 4A, the illumination devices each comprising a LED strip 3, is illustrated attached to a door frame 45 of the refrigerator. Refrigerated merchandise 11 is stored on shelves 47 in the refrigerator behind glass display doors 49 for display to customers 13. When a customer approaches the refrigerator, a built-in sensor of the refrigerator detects the presence of a customer and will send a signal to a controller (not visible) to switch on the illumination device to illuminate the merchandise. In the figure the LEDs are shown as individual spots because the doors are in slightly opened position, but these LEDs will be seen as a continuous line of light when the doors of the refrigerator are closed due to the illumination device comprising the screen 27 and the diffuser (not shown). Two illumination devices are installed on the door frame between each of the refrigerator doors and is typically about 1.20 meter from adjacent door posts 51. In the illustrated embodiment, light is emitted from each of the individual LEDs carried by the illumination device and refracted by the lens (not shown) to provide an evenly distributed and desirable light pattern for uniform illumination of the merchandise displayed in the refrigerator. Typically, the door of refrigerator is lined with glass so that customers can view the merchandise in the refrigerator prior to opening the door. A plurality of LEDs is generally necessary to provide sufficient lighting to uniformly illuminate the interior of the refrigerator. As illumination devices are installed on both sides of the door frame, as shown in FIG. 4B, the merchandise can be illuminated from two opposite directions. As each illumination device is individually controllable, with each LED thereof being individually controllable, a desired color distribution and light intensity distribution can be chosen for optimal illumination of the displayed merchandise.

[0034] FIG. 5 shows a luminaire 37 comprising an illumination device 1 according to the invention. The luminaire is mounted onto a wall 53 with a housing 39 which accommodates an illumination device. The illumination device is oriented in such a manner in the housing that it provided grazing light 55 to the wall, for a wall washing effect and to illuminate an object 11 hanging on said wall, for example a painting. As the illumination device comprises a screen and a diffuser (not visible) neither the individual LEDs nor reflected images of the LEDs of the LED strip of the illumination device are visible to a viewer 13.