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(11) | EP 2 829 787 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Lamp structure |
| (57) Lamp structure (11) comprising a support shell (13) which defines a chamber (15)
in which engagement surfaces (17a,17b,17c) are housed for groups (19a,19b,19c) of
illuminating elements (21a,21b,21c), provided each with an illuminating device (23)
and a corresponding optical system (25a,25b,25c), wherein the illuminating elements
(21a,21b,21c) belonging to the same group are mutually homogeneous, i.e. they define
substantially the same path for the light emitted by the respective illuminating device
(23), and wherein the illuminating elements belonging to different groups are inhomogeneous,
i.e. they define different paths for the light emitted by the respective illuminating
device (23).
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Technical Field
[0001] The present invention relates to a lamp structure. More particularly, the invention relates to a lamp structure capable of being used for outdoor lighting, for instance for street lighting. Still more particularly, the invention relates to a lamp structure equipped with a plurality of point-like light sources such as, for instance, LEDs (Light Emitting Diodes).
Prior Art
[0002] In the lighting of outdoor environments, for example in street lighting, hanging lamps, usually attached to a vertical pole driven into the ground, are commonly used.
[0003] With reference to Figure 1, there is schematically shown the distribution of light in a typical street installation, where DRH indicates the light flux directed upwards, RFH indicates the light flux reflected upwards, NSL indicates non-useful light, USL indicates useful light, DRG indicates direct glare, ISL indicates intrusive light, for instance with respect to a building BLD, and ATL indicates the ground area to be lighted.
[0004] One of the problems encountered in the making of street lamps is how to avoid that the luminosity generated by the lamp is dispersed outside the area ATL to be lighted.
[0005] In order to solve this problem, solutions were proposed in the past that provide to house the light source within a seat equipped with reflecting screens that concentrate light towards the area to be lighted.
[0006] At present, in order to obtain good uniformity of lighting on the ground, installers have to orientate the lamps relative to the angles θ and ψ, i.e. around a transversal axis and a longitudinal axis, respectively, as schematically shown in Figures 2A e 2B, respectively.
[0007] If not properly performed, this operation involve several drawbacks, because the light flux directed upwards DRH as well as the non-useful light NSL and the intrusive light ISL can turn to be non-negligible.
[0008] A first object of the invention is therefore to provide a lamp structure that is free from the drawbacks of the prior art and has performances that are substantially independent of the installation conditions and, consequently, of mounting errors.
[0009] Moreover, as such lamps are located outdoors, it is necessary that the chamber which houses the light source be made watertight in order to protect the latter from bad weather conditions. Such chamber is therefore separated below from the outer environment by means of a transparent wall, usually made of glass.
[0010] The presence of glass or other transparent material interposed between the light source and the area to be lighted, however, inevitably brings about the rising of the phenomenon of refraction, caused by the change in the direction of the light ray when passing from a material to another, when these materials have different thicknesses. As is known, under such circumstances light does not propagate in straight line, but it undergoes deviations depending on the physical properties of the materials passed through. Still owing to the transparent wall, besides the phenomenon of refraction, there further occur the phenomenon of reflection, because the light does not passes entirely through the glass sheet but it is partially reflected at an angle equal and co-planar with the angle of incidence, and the phenomenon of absorption, which reduces the light power emitted by the lamp.
[0011] A further object of the invention is therefore to provide a lamp structure that does not show the drawbacks of prior art and does not require a transparent partition wall.
[0012] A not least object of the invention is to provide a lamp structure than can be industrially manufactured at competitive costs.
Summary of the Invention
[0013] The aforesaid and further objects are achieved by a lamp structure as claimed in the appended claims.
[0014] A first advantage of the invention is that the residual light flux directed upwards DRH is substantially zeroed.
[0015] Such advantageous result is mainly achieved thanks to the arrangement of the lamp structure, to the configuration of the optical systems and to the preferable absence of protective glass.
[0016] The absence of transparent protective material further makes the structure lighter and increases system efficiency of approximately 10%.
[0017] Owing to these features, the installation of the lamp structure is standardized and substantially free from alignment errors.
[0018] The lamp structure according to the invention further complies advantageously with the increasingly stricter norms aimed at reducing light pollution upwards and glare and at promoting energy saving.
[0019] The lamp structure according to the invention further allows to uniform the design criteria of street lighting installations, thus improving the light quality of the installations themselves in favor of safety in road traffic.
Brief Description of the Drawings
[0020] A preferred embodiment of the lamp structure according to the invention will now be described by way of non-limiting example with reference to the attached drawings, in which:
- Figure 1 is a schematic view of light distribution in a street installation;
- Figures 2A and 2B respectively show the orientation movements to which a street lamp according to the known art is subjected upon its installation;
- Figure 3 is a perspective top view of the lamp structure according to the invention;
- Figure 4 is a perspective bottom view of the lamp structure of Figure 3;
- Figure 5 is a bottom plan view of the lamp of Figure 3;
- Figures 6A, 6B, 6C are side views of as many illuminating elements;
- Figures 7A, 7B, 7C are top plan views of the illuminating elements of Figures 6A, 6B, 6C, respectively;
- Figure 8 is an enlarged section of an engagement surface for the illuminating elements;
- Figure 9 is a side view, partially in section, of the lamp of Figure 3.
Description of a Preferred Embodiment
[0021] With reference to Figures 3, 4 and 5, a preferred embodiment of the lamp structure according to the invention, which is indicated as a whole with reference 11, is illustrated.
[0022] The lamp structure 11 comprises a supporting chassis 13 in which there is defined a chamber 15 capable of housing a plurality of engagement surfaces 17a,17b,17c for groups 19a,19b,19c of illuminating elements 21a,21b,21c.
[0023] The illuminating elements 21a,21b,21c are each provided with an illuminating device 23 and a corresponding optical system 25a,25b,25c.
[0024] According to the invention, the illuminating elements 21a,21b,21c belonging to the same group of illuminating elements are mutually homogeneous, i.e. they define substantially the same path for the light emitted by the respective illuminating device 23, whereas the illuminating elements 21a,21b,21c belonging to different groups are inhomogeneous, i.e. they define different paths for the light emitted by the respective illuminating device 23.
[0025] The supporting chassis 13 preferably is substantially dome-shaped and defines therein the chamber 15 in which the engagement surfaces 17a,17b,17c for the groups 19a,19b,19c of illuminating elements 21a,21b,21c are housed.
[0026] As can better be seen in Figure 5, according to a preferred embodiment of the invention, the engagement surfaces 17a,17b,17c are in number of three, are substantially planar and are oriented within the chamber 15 so as to define a configuration having a substantially trapezoidal cross-section, i.e. with respect to a vertical plane perpendicular to the surface 17a in Figure 5. The trapezoidal configuration comprises a central engagement surface 17a and two lateral engagement surfaces 17b,17c. The central engagement surface 17a further comprises a substantially rectangular central portion 18, and a substantially U-shaped perimetral portion 20 which partially surrounds the central portion 18.
[0027] For the sake of description clarity, in Figure 5 the perimeter of the central portion 18 and of the perimetral portion 20 is indicated by a dashed line and by a dash-dot line, respectively.
[0028] According to the invention, the central portion 18 incorporates a first group 19a of mutually homogeneous illuminating elements 21a and the perimetral portion 20 incorporates a second group 19b of inhomogeneous illuminating elements 21b, the elements 21a of the first group 19a being inhomogeneous with respect to those 21b of the second group 19b.
[0029] Still according to the invention, the lateral engagement surfaces 17b, 17c comprise a third group 19c of illuminating elements 21c that are mutually homogeneous, but inhomogeneous with respect to the illuminating elements 21a, 21b of the first group 19a and second group 19b.
[0030] Therefore, in this preferred embodiment the lamp structure 11 is provided with three groups 19a,19b,19c, or different kinds, of illuminating elements 21a,21b,21c, a first kind 21a being associated to the central portion 18, a second kind 21b to the perimetral portion 20 and a third kind 21c to the two lateral engagement surfaces 17b,17c.
[0031] In accordance with this preferred embodiment of the invention, the illuminating elements 21a,21b,21c are distributed on the engagement surfaces 17a,17b,17c in parallel rows and define corresponding matrixes of illuminating elements for each engagement surface.
[0032] Still with reference to the illustrated embodiment, the central engagement surface 17a is further defined on a pair of engagement plates 27 arranged mutually adjacent and the lateral engagement surfaces 17b,17c are defined on as many engagement plates 27. However, it will be possible to provide that the central engagement surface 17a and the lateral engagement surfaces 17b,17c are defined on a different number of plates or even on a single plate. The illuminating elements 21a,21b,21c are engaged on the engagement surfaces 17a,17b,17c of the plates 27.
[0033] The illuminating devices 23 of the illuminating elements 21a,21b,21c are electrically powered by means of conductors (not shown) that may for instance pass through the plate 27 through appropriate holes or run on the engagement surface itself of the plate 27, possibly in the form of tracks of electrically conductive material of the kind used in printed circuit boards.
[0034] The optical system 25a,25b,25c comprises a body 29a,29b,29c of refractive material, for instance polycarbonate, which incorporates a corresponding illuminating device 23.
[0035] The body 29a,29b,29c of refractive material further comprises a portion 31a,31b,31c acting as a lens for the light emitted by the illuminating device 23 provided in the body itself and a base 33a,33b,33c, preferably having a disk-kike shape, for securing the element 21a,21b,21c to the plate 27.
[0036] As appreciable when comparing the configurations of the optical systems 25a,25b,25c illustrated in Figures 6A, 6B, 6C and 7A, 7B, 7C, these optical systems 25a,25b,25c are advantageously differentiated depending on their arrangement within the chamber 15 of the lamp structure and have therefore to be arranged and oriented correctly on the plate 27.
[0037] Referring particularly to Figure 8, in order to facilitate mounting of the elements 21a,21b,21c on the engagement plates 27, the base 33a,33b,33c has at least one, preferably two, anti-error pin(s)35 protruding axially from the base 33a,33b,33c, on the side opposite to the lenses 31a,31b,31c, and being received in a corresponding seat 37 provided in the plate 27.
[0038] The base 33a,33b,33c is further associated to the engagement surface of the plate 27 by means of a layer 39 of sealing substance, for instance a synthetic resin, whereby the illuminating device 23 is housed in a seat substantially watertight with respect to the environment outside the illuminating element. The layer 39 further preferably extends continuously between the illuminating elements 21a,21b,21c and seals the feeding conductors and/or the electric conductor tracks provided for feeding the illuminating devices 23.
[0039] It is to be noted that, although the illuminating element 21a of the first group 19a is visible in Figure 8, the pin 35 and the seat 37 will be provided also for the illuminating elements 21b,21c of the other groups 19b,19c.
[0040] In the illustrated embodiment, the lamp structure 11 includes three homogeneous groups 19a,19b,19c of optical systems 25a,25b,25c, each equipped with corresponding lenses 31a,31b,31c, i.e. lenses of the first group, lenses of the second group and lenses of the third group. In an embodiment of the lamp structure 11 according to the invention there are provided ten lenses of the first group 19a, twenty lenses of the second group 19b and thirty lenses of the third group 19c, for a total amount of sixty illuminating elements 21a,21b,21c. Other amounts for the various groups are however possible.
[0041] Advantageously the optical systems belonging to different groups have a different diffraction effect in order to optimally uniform the light flux on the ground.
[0042] As better visible in Figure 4, which shows the lamp structure 11 in a configuration ready for use, the chamber 15 housing the engagement surfaces communicates with the outer environment to be lighted, i.e. it is free from transparent surfaces separating the chamber 15 from the outer environment. The absence of a transparent partition wall advantageously determines the absence of phenomena of diffraction, absorption and reflection, improves the lighting efficiency and reduces light pollution by substantially zeroing it over 90°. Owing to the fact that the lamp structure 11 according to the invention is free from such transparent separation surface, typically made of glass, a structure is obtained that is safer and less subjected to damages.
[0043] According to a preferred embodiment of the invention, the illuminating devices 23 are of a point-like type and comprise each at least one LED (Light Emitting Diode). In an embodiment where the devices 23 are LEDs, the overall power of each plate 27 is about 15W.
[0044] Still referring to Figure 4, the supporting chassis 13 preferably comprises an engagement portion 41, possibly orientable, capable of receiving a pole or similar supporting element, which will be oriented substantially perpendicular to the central engagement surface 17a. As better visible in Figure 9, the engagement portion 41 will further preferably be associated to the chassis 13 by means of a toothed orientable system 53 and will therefore be able to receive for instance a horizontal cantilever pole, i.e. parallel to the central engagement surface 17a, or incline, typically of 15°, by appropriately positioning the portion 41. In this way the structure 11 can advantageously be employed for obtaining a lighting lamp post, for instance for street lighting.
[0046] Referring to Figure 8, the lamp structure 11 may comprise a power supply 43, for instance of the dimmerable kind of 60W or 120W, a stationary lower cover and a removable lower cover 47, a video camera for surveillance 49, modules 51 for instance for remote control, Wi-Fi, Hot spot, Memory card, phone card, etc.
1. Lamp structure (11) comprising a supporting chassis (13) which defines a chamber (15)
in which engagement surfaces (17a,17b,17c) are housed for groups (19a,19b,19c) of
illuminating elements (21a,21b,21c), provided each with an illuminating device (23)
and a corresponding optical system (25a,25b,25c), wherein the illuminating elements
(21a,21b,21c) belonging to the same group are mutually homogeneous, i.e. they define
substantially the same path for the light emitted by the respective illuminating device
(23), and wherein the illuminating elements belonging to different groups are inhomogeneous,
i.e. they define different paths for the light emitted by the respective illuminating
device (23).
2. Structure according to claim 1, wherein the supporting chassis (13) is substantially
dome-shaped and defines therein the chamber (15) housing the engagement surfaces (17a,17b,17c)
for the groups (19a,19b,19c) of illuminating elements, wherein the engagement surfaces
(17a,17b,17c) are in number of three, are substantially planar and are oriented within
the chamber (15) so as to define a configuration having a substantially trapezoidal
cross-section comprising a central engagement surface (17a) and two lateral engagement
surfaces (17b, 17c) .
3. Structure according to claim 2, wherein the central engagement surface (17a) comprises
a substantially rectangular central portion (18) incorporating a first group (19a)
of mutually homogeneous illuminating elements, and a substantially U-shaped perimetral
portion (20) which partially surrounds the central portion 18 and which incorporates
a second group (19b) of mutually homogeneous illuminating elements, and wherein the
lateral surfaces (17b,17c) comprise a third group (19c) of mutually homogeneous illuminating
elements, each of the three groups of illuminating elements (21a,21b,21c) being inhomogeneous
with respect to the other two groups.
4. Structure according to claim 3, wherein the illuminating elements (21a,21b,21c) are
distributed on the engagement surfaces (17a,17b,17c) in parallel rows and define corresponding
matrixes of illuminating elements (21a,21b,21c) for each engagement surface (17a,17b,17c).
5. Structure according to claim 3 or 4, wherein the engagement surfaces (17a,17b,17c)
are defined on at least one engagement plate (27) on which the illuminating elements
(21a,21b,21c) are engaged, the illuminating devices (23) being electrically powered
by means of conductors passing through the plate (27) or running over its engagement
surface (17a,17b,17c) and wherein the optical system (25a,25b,25c) comprises a body
(29a,29b,29c) of refractive material which incorporates the illuminating device (23).
6. Structure according to claim 5, wherein the body (29a,29b,29c) of refractive material
is associated to the engagement surface of the corresponding plate (27) by means of
a layer (39) of sealing substance, whereby the illuminating device (23) is housed
in a substantially watertight seat.
7. Structure according to any of the preceding claims, wherein the illuminating devices
(23) comprise each at least one LED (Light Emitting Diode).
8. Structure according to any of the preceding claims, wherein the chamber (15) housing
the engagement surfaces (17a,17b,17c) communicates with the outer environment.
9. Structure according to any of the preceding claims, wherein the supporting chassis
(13) comprises an engagement portion (41) capable of receiving a supporting pole oriented
substantially perpendicular or parallel to the central engagement surface (17a).
10. Structure according to any of the preceding claims, wherein the supporting chassis
(13) incorporates a power supply (43) for the illuminating devices, a video camera
for surveillance (49), modules (51) for remote control, Wi-Fi, Hot spot, Memory card,
phone card.