WO2013136217A1

WO2013136217A1 - A lighting device, a lighting luminaire and a lighting system

Info

Publication number: WO2013136217A1
Application number: PCT/IB2013/051656
Authority: WO
Inventors: Wen Ting CHENG; Wenyi Li
Original assignee: Koninklijke Philips N.V.
Priority date: 2012-03-13
Filing date: 2013-03-01
Publication date: 2013-09-19

Abstract

The invention proposes a lighting device (10). The lighting device (10) comprises a lighting unit (100) configured to emit a first light beam that targets a first surface (A) and generates a uniform illuminance within a first area (F) of the first surface, and a second light beam that targets a second surface (B) and generates a uniform illuminance within a second area (S) of the second surface, the second surface (B) being substantially parallel to the first surface (A) and being adjacent to the lighting unit (100) with respect to the first surface (A), wherein at least part of the second area (S) of the second surface (B) is overlapped with a complement of a third area (T) in the coverage of an area where the first area (F) of the first surface (A) projects on the second surface (B), the third area (T) being an illuminating coverage of the first light beam on the second surface (B) and being smaller than the first area (F). The invention also provides a lighting luminaire (L) comprising the lighting device (10), and a lighting system comprising a plurality of lighting luminaires (L).

Description

A LIGHTING DEVICE, A LIGHTING LUMINAIRE AND A LIGHTING SYSTEM

Field of the Invention

The present invention relates to lighting, and particularly to a lighting device, a lighting luminaire comprising the lighting device, and a lighting system comprising a plurality of lighting luminaires.

Background of the Invention

With fast pace of urbanization and well road construction, road lighting is playing an important role in the whole city lighting system. To achieve a better lighting effect, for example, uniform illuminance, enough luminance level, no glare, etc., low-height road lighting luminaires, typically mounted at a height no higher than 1.2m, are applied.

For low-height road lighting luminaires mounted on the road, the height of the lighting unit of each lighting luminaire is close to the sight of view of the driver and the interval between adjacent lighting luminaires is smaller than that of the conventional road lighting luminaire, hence the flicker perceived by the driver when driving past these low-height road lighting luminaires is much more severe, compared to the conventional road lighting luminaires. Typically, flicker effects perceived by the driver happen in two locations. One is on the side window of the car, which is caused by the light directly from the low-height road lighting luminaire to the eyes; the other is on the dashboard, which is caused by the light incident on it and reflecting to the eyes. Based on an experiment conducted under both 5Hz and lOHz which simulate the flicker frequency of different driving speed, the result shows that the latter one, i.e. the flicker on the dashboard, is more disturbing for the driver, which may cause considerable discomfort.

To be specific, referring to FIGS, la- lb, each low-height road lighting luminaire L emits a light beam that targets the first surface A, for example, the road surface, and generates a uniform illuminance within the first area F of the first surface A. The first area F of each low-height road lighting luminaire L is consecutive to one another, and thus the low-height road lighting luminaires could provide a uniform and consecutive illuminance on the first surface A. However, for any surface that is above the first surface

A and parallel to the first surface A, for example, the third surface T where the dashboard/engine hood surface of a car M is located, the illuminating coverage of the light beam emitted by each low-height road lighting luminaire L on this third surface T is smaller than the first area F on the first surface A; therefore the illuminating coverage on this third surface T is not consecutive to one another, which may cause flicker to the driver when driving past the low-height road lighting luminaires.

Object and Summary of the Invention

Based on above drawbacks, in one aspect, one embodiment of the invention provides a lighting device. The lighting device comprises a lighting unit configured to emit a first light beam that targets a first surface and generates a uniform illuminance within a first area of the first surface, and a second light beam that targets a second surface and generates a uniform illuminance within a second area of the second surface, the second surface being substantially parallel to the first surface and being adjacent to the lighting unit with respect to the first surface, wherein at least part of the second area of the second surface is overlapped with a complement of a third area in the coverage of an area where the first area of the first surface projects on the second surface, the third area being an illuminating coverage of the first light beam on the second surface and being smaller than the first area.

Advantageously, the second area may be an area where the first area of the first surface projects on the second surface, or may be the complement of the third area in the coverage of an area where the first area of the first surface projects on the second surface.

With the arrangement of the lighting device, a first light beam is emitted by the lighting unit of the lighting device, which generates a uniform illuminance within the first area F of the first surface A, and a second light beam is further provided by the lighting unit and targets the second surface B, which generates a uniform illuminance within the second area S of the second surface B, as shown in FIGS, 2a-2b. The second area S may be an area where the first area F of the first surface A projects on the second surface B, as shown in FIG. 2a, or be a complement of the third area T that is an illuminating coverage of the first light beam on the second surface B in the coverage of an area where the first area F of the first surface A projects on the second surface B, as shown in FIG. 2b. In this manner, when a plurality of lighting luminaires, each including the lighting device, are mounted on the road surface for road lighting, the illuminating coverage of each lighting luminaire on the second surface B (for example, the dashboard/engine hood surface) is consecutive to one another, which can significantly reduce flicker to the driver while driving past these lighting illuminaires.

Advantageously, the lighting unit comprises a first lighting unit configured to emit the first light beam, and a second lighting unit configured to emit the second light beam.

Advantageously, the lighting unit comprises a light source configured to emit a light beam; and an optical element disposed adjacent to the light source and configured to transform the light beam emitted from the light source into the first light beam and the second light beam. The optical element may for example be a reflector including a reflecting surface formed by revolving a CPC curve around a first axis by a predetermined angle, the CPC curve having an aperture at its vertex, the first axis being co-plane with the CPC curve, being substantially perpendicular to the axis of symmetry of the CPC curve and being located at or outside the aperture of the CPC curve, wherein the CPC curve is characterized by equation of

2 f

r = ^-sin( - )- a , where f, = a(l + sin )

l - cos

where is the acceptance angle of the CPC curve and a is the lateral focal shift of the CPC curve, wherein the light source is disposed at an entrance of the reflecting surface corresponding to the aperture.

In another aspect, one embodiment of the invention provides a lighting luminaire. The lighting luminaire comprises a support to be mounted on the road surface; and an abovementioned lighting device mounted on the support and oriented relative to the road surface such that the first surface is substantially parallel to the road surface.

In still another aspect, one embodiment of the invention provides a lighting system. The lighting system comprises a plurality of abovementioned lighting luminaires to be mounted on the road surface and spaced apart one another, wherein the lighting device of each lighting luminaire is oriented relative to the road surface such that the first surface corresponding to each lighting luminaire is substantially parallel to the road surface and the uniform illuminance of each lighting luminaire on the first surface and second surface is consecutive to one another.

Brief Description of the Drawings

The above and other objects and features of the present invention will become more apparent from the following detailed description considered in connection with the accompanying drawings, in which:

FIG. la shows a front view of an application scenario to which conventional low-height road lighting luminaires are applied;

FIG. lb shows a top view of a lighting pattern generated by conventional low-height road lighting luminaires of FIG. la;

FIG. 2a shows a front view of an application scenario to which a lighting device according to one embodiment of the invention is applied;

FIG. 2b shows a front view of an application scenario to which a lighting device according to another embodiment of the invention is applied;

FIG. 3a shows a perspective view of an application scenario to which a lighting luminaire according to one embodiment of the invention is applied;

FIG. 3b shows a top view of one kind of lighting pattern generated by the lighting luminaire of FIG. 3a;

FIG. 3c shows a top view of another kind of lighting pattern generated by the lighting luminaire of FIG. 3a;

FIG. 4 shows a perspective view of an application scenario to which a lighting system according to one embodiment of the invention is applied;

FIG. 5 shows a schematic view of a lighting device according to one embodiment of the invention;

FIG. 6 shows a sectional view of an application scenario to which the lighting device of FIG. 5 is applied.

FIG. 7 shows a perspective view of a lighting device according to another embodiment of the invention, the lighting device including a light source and a reflector;

FIG. 8 shows a schematic view of the CPC curve of the reflector of FIG. 7.

Detailed Description

Reference will now be made to embodiments of the invention, one or more examples of which are illustrated in the figures. The embodiments are provided by way of explanation of the invention, and are not meant as a limitation of the invention. For example, features illustrated or described as part of one embodiment may be used with another embodiment to yield still a further embodiment. It is intended that the invention encompass these and other modifications and variations as come within the scope and spirit of the invention. In the context, the term "uniform illuminance" means the ratio of illuminance of any point in an illuminating coverage to that of the whole illuminating coverage is higher than a Chinese standard value, i.e., 0.6. It is to be noted that the standard value may vary in various countries; namely, in different countries, the definition of "uniform illuminance" may differ.

Referring to FIG. 3a, the lighting device 10 of the invention comprises a lighting unit 100 configured to emit a first light beam that targets a first surface A and generates a uniform illuminance within a first area F of the first surface A, and a second light beam that targets a second surface B and generates a uniform illuminance within a second area S of the second surface B, the second surface B being substantially parallel to the first surface A and being adjacent to the lighting unit 100 with respect to the first surface A.

At least part of the second area S of the second surface B is overlapped with a complement of a third area T in the coverage of an area where the first area F of the first surface A projects on the second surface B, the third area T being an illuminating coverage of the first light beam on the second surface B and being smaller than the first area F. For one example, the second area S may be an area (denoted by diagonal lines) where the first area F of the first surface A projects on the second surface B, as shown in FIG. 3b. For another example, the second area S may be the complement (denoted by diagonal lines) of the third area T in the coverage of an area where the first area F of the first surface A projects on the second surface B, as shown in FIG. 3c. It is to be noted that the term

"project" is not limited to the situation of "vertically project"; it may also include the situation of "project by a slight angle".

The lighting device 10 of the invention may be applicable to any suitable lighting scenario. For example, the lighting device 10 may be mounted on a support to constitute a lighting luminaire L. A plurality of lighting luminaires L may be mounted on the road surface and spaced apart one another to form a road lighting system, as shown in FIG. 4, wherein, the lighting device 10 of each lighting luminaire L is oriented relative to the road surface such that the first surface A corresponding to each lighting luminaire L is substantially parallel to the road surface. Advantageously, the first surface A may be overlapped with the road surface and the second surface B may be a surface where the dashboard/engine hood surface is located.

In such a road lighting system, as the second light beam of each lighting luminiare L is delivered to their respective second area S of the second surface B, for example, to an area where their respective first area F of the first surface A projects on the second surface B, or the complement of their respective third area T in the coverage of an area where their respective first area F of the first surface A projects on the second surface B, the illuminating coverage of each lighting luminaire L on the second surface B, i.e. the dashboard/engine hood surface, is substantially consecutive to one another, which can significantly reduce or even eliminate flicker to the driver while driving past these lighting illuminaires L.

The height (i.e. the first predetermined height) the second surface B with respect to the first surface A may be set in accordance with different scenarios. For example, when the road where the road lighting system is applied is dedicated for cars, the first predetermined height may be set to be a value equal to the height of engine hood surfaces of cars with respect to the road surface; when the road is dedicated for trucks, the first predetermined height may be set to be a value equal to the height of engine hood surfaces of trucks with respect to the road surface; when the road is for both, the first predetermined height may be set to be a value equal to the height of engine hood surfaces of trucks with respect to the road surface, i.e. the largest height among heights of engine hood surfaces of different kind of vehicles with respect to the road surface. For example, the first predetermined height is in the range of 0.6 to 2.0m.

Further, the lighting device 10 of each lighting illuminaire L may be mounted at a second predetermined height away from the road surface. For a low-height road lighting luminaire, the second predetermined height may be no higher than 1.2m.

The lighting unit 100 of the lighting device 10 may be implemented by various ways. Hereinafter, different configuration of the lighting unit 100 will be described in detail by using the second area S being an area where the first area F of the first surface A projects on the second surface B as an example.

For one example, referring to FIG. 5 and in conjunction with FIG. 3, the lighting unit 100 comprises a first lighting unit 110 and a second lighting unit 120. The first lighting unit 110 is configured to emit the first light beam that targets the first surface A and generates a uniform illuminance within the first area F of the first surface A; the second lighting unit 120 is configured to emit the second light beam that targets the second surface

B and generates a uniform illuminance within the second area S of the second surface B. The first and second lighting unit 110 and 120 may be any suitable lighting unit capable of generating a uniform illuminance on the first and second surface A and B, for example, the first and second lighting unit 110 and 120 may be the lighting unit/lighting device described in Philips Patent application No. PCT/CN2010/080494, or the lighting unit/lighting device described in Philips Patent application No. PCT/CN2011/084952.

Further, the first lighting unit 110 and the second lighting unit 120 may be mounted at a different height away from the road surface to achieve above lighting effects. For example, the second lighting unit 120 for emitting the second light beam may be mounted at a position higher than where the first lighting unit 110 for emitting the first light beam is mounted with respect to the road surface.

Alternatively, the first lighting unit 1 10 and the second lighting unit 120 may be mounted adjacent to each other and at the same height away from the road surface to get above lighting effects. To be specific, referring to FIG. 6, it is assumed that the road surface is one-way road surface of a width W, both the first lighting unit 110 and the second lighting unit 120 are mounted at a height Hi away from the road surface, and the second surface B is at a height H₂ away from the first surface A, i.e. the road surface. The first lighting unit 110 emits the first light beam targeting the first surface A, the central intensity direction CI of which directs toward the center Oi of the first surface A, i.e. the road surface; the second lighting unit 120 emits the second light beam targeting the second surface B, the central intensity direction C2 of which directs toward the center 0₂ of the second surface B. The angle Θ of the central intensity direction C2 and central intensity direction C 1 can be obtained in the formula of

9=arctg[W/2/( H H₂)]-arctg(W/2/ Hi)

That is to say, to achieve the lighting effects, during assembly, the first lighting unit 1 10 and the second unit 120 should be oriented relative to the road surface such that the first surface A is parallel to the road surface as well as the angle Θ equals to a value of arctg[W/2/( ¾- H₂)]-arctg(W/2/ Hi).

For another example, referring to FIG. 7, the lighting unit 100' comprises a light source 130 configured to emit a light beam, and an optical element 140 disposed adjacent to the light source 130 and configured to transform the light beam emitted from the light source 130 into the first light beam and the second light beam.

The light source 130 may be a light emitting diode (LED) light source, a fluorescent light source, or a halogen light source, for example. Further, the LED light source may be a multi-chip LED light source or a single-chip LED light source. Advantageously, a multi-chip LED light source, which could achieve high luminous flux, may be used herein, and thus the lighting unit 100 Of the invention can provide sufficient luminous intensity on the road surface.

The optical element 140 may take on any suitable configuration, but generally be a reflector, as shown in FIG. 7. The reflector 140 includes a reflecting surface formed by revolving a CPC (Compound Parabolic concentrator) curve around a first axis y by a predetermined angle, for example 180°. Referring to FIG. 8, the CPC curve 20 has two tilted curves 203 and 204, an aperture 201 at its vertex, and an aperture 202 opposite the aperture 201. Generally, the aperture 201 is smaller than the aperture 202. The first axis y is co-plane with the CPC curve 20, namely being situated in the same plane containing the CPC curve 20. The first axis y is substantially perpendicular to axis x, which is the axis of symmetric of the CPC curve 20. Moreover, the first axis y is located at or outside the aperture 201. In an example, the first axis y may be located just at the aperture 201, as shown in FIG. 8. In another example, the first axis y may be located outside the aperture 201, namely at the left side of the aperture 201.

In the polar coordinate s stem shown in FIG. 8, the CPC curve 20 can be expressed as ) - a , where f, = a{l + sin 0_max )

where r and φ are two variables in the polar coordinate system, r representing radius and φ representing angle, 0_max is the acceptance angle of the CPC curve 20 and a is the lateral focal shift of the CPC curve 20.

By revolving the CPC curve 20 around the first axis y by 180°, the reflecting surface of the reflector 140 of FIG. 8 is achieved, wherein the curve 203 forms the upper surface 142 and the curve 204 forms the lower surface 144. The light source 130 is disposed at an entrance of the reflecting surface of the reflector 140 corresponding to the aperture 201. First part of the light beam emitted by the light source 130 is reflected by the upper surface 142 as the first light beam that targets the first area F of the first surface A, and second part of the light beam emitted by the light source 130 is reflected by the lower surface 144 as the second light beam that targets the second area S of the second surface B.

The angle between the center intensity direction of the second light beam and the center intensity direction of the first light beam equals to 20_max . Still using the scenario of FIG. 6 as an example, 20_max can be obtained in the formula of

26>_max =arctg[W/2/( H H₂)]-arctg(W/2/ ¾) That is to say, to achieve the lighting effects, the reflector with the acceptance angle a

m^ax satisfying above formula should be chosen.

It is to be noted that the predetermined angle of revolving CPC curve being 180° is an illustrative example; in practical usage, it may be any other angle in the range of 90° to 180°.

Assuming the scenario that Hi=1.2m, H₂=lm, W=8m, and the lighting source 130 is a multichip LED with a radius of 5.2mm, then the size of the aperture 202 of the reflector 140 can be obtained as follows.

0_max ={arctg[W/2/( H H₂)]-arctg(W/2/ ¾)}/ 2

= (arctg20- arctg3.33)/2

=7°

As the radius of the multichip LED is 5.2mm, the size of the aperture 201 of the reflector 140 should be set to be larger than 10.4mm so as to expose the multichip LED. Hence, it is assumed that a= 5.3mm, and then j can be obtained in the formula of fi = a(l + sin 0_max ) = 5.3(1 + sin7°) = 5.9mm

Then r = ²^ sin( - θ max ) / - α = ₁ ^{1 L 8} sin(< - I⁰ )- 5.3

- COS ifflf 1l -- CcOoSsffl

In order to constrain the light emitting angle of the reflector 140 within the range of [- 0max ,+ 0max ] ' Φ should be no larger than 2 0_max . l l .8

When =2 0_max =l4°, then r_aper = - — -sin(7° )- 5.3 =43. l mm

l - - ccoossll4

Therefore, the size of the aperture 202 of the reflector 140 is 86.2 mm.

It should be noted that the above described embodiments are given for describing rather than limiting the invention, and it is to be understood that modifications and variations may be resorted to without departing from the spirit and scope of the invention as those skilled in the art readily understand. Such modifications and variations are considered to be within the scope of the invention and the appended claims. The protection scope of the invention is defined by the accompanying claims. In addition, any of the reference numerals in the claims should not be interpreted as a limitation to the claims. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The indefinite article "a" or "an" preceding an element or step does not exclude the presence of a plurality of such elements or steps.

Claims

What is claimed is:

1. A lighting device, comprising:

a lighting unit configured to emit a first light beam that targets a first surface and generates a uniform illuminance within a first area of the first surface, and a second light beam that targets a second surface and generates a uniform illuminance within a second area of the second surface, the second surface being substantially parallel to the first surface and being adjacent to the lighting unit with respect to the first surface,

wherein at least part of the second area of the second surface is overlapped with a complement of a third area in the coverage of an area where the first area of the first surface projects on the second surface, the third area being an illuminating coverage of the first light beam on the second surface and being smaller than the first area.

2. The lighting device of claim 1 , wherein the second area is an area where the first area of the first surface projects on the second surface.

3. The lighting device of claim 1 , wherein the second area is the complement of the third area in the coverage of an area where the first area of the first surface projects on the second surface.

4. The lighting device of claim 1 , wherein the lighting unit comprises a first lighting unit configured to emit the first light beam, and a second lighting unit configured to emit the second light beam.

5. The lighting device of claim 1, wherein the lighting unit comprises:

a light source configured to emit a light beam; and

an optical element disposed adjacent to the light source and configured to transform the light beam emitted from the light source into the first light beam and the second light beam.

6. The lighting device of claim 1 , wherein the second surface is at a first predetermined height away from the first surface, the first predetermined height being in the range of 0.6 to 2.0m.

7. A lighting luminaire, comprising:

a support to be mounted on the road surface;

the lighting device according to any of claims 1 to 6 mounted on the support and oriented relative to the road surface such that the first surface is substantially parallel to the road surface.

8. The lighting luminaire of claim 7, wherein the first surface is overlapped with the road surface.

9. The lighting luminaire of claim 7, wherein the lighting device is mounted at a second predetermined height away from the road surface, the second predetermined height being no higher than 1.2m.

10. A lighting system, comprising a plurality of lighting luminaires according to claim 7 to be mounted on the road surface and spaced apart one another, wherein the lighting device of each lighting luminaire is oriented relative to the road surface such that the first surface corresponding to each lighting luminaire is substantially parallel to the road surface and the uniform illuminance of each lighting luminaire on the first surface and second surface is consecutive to one another.