EP1785667B1

EP1785667B1 - Optical group with an adjustable light beam

Info

Publication number: EP1785667B1
Application number: EP06123798A
Authority: EP
Inventors: Gian Pietro Beghelli
Original assignee: Beghelli SpA
Current assignee: Beghelli SpA
Priority date: 2005-11-11
Filing date: 2006-11-10
Publication date: 2009-09-30
Anticipated expiration: 2026-11-10
Also published as: EP1785667A2; EP1785667A3; DE602006009458D1; ATE444466T1; ITVI20050297A1

Abstract

An optical group with an adjustable light beam, comprising at least one lamp-holder device, at least two linear fluorescent lamps (10, 11) and a specular reflector (12); in the centre of the body (5) of the reflector (12) there are at least two curvilinear surfaces (6, 16-19), which, by varying their angular position, allow a variation in the form of the light emission of a lighting appliance, in relation to the various application requirements. Solutions such as those projected allow high efficiency levels of the lighting appliance to be maintained and obtained in particularly restricted volumes.

Description

The present invention generally relates to an optical group with an adjustable light beam.
More specifically, the invention relates to a lighting appliance, equipped with an optical group designed so that it can easily and rapidly vary the form of the light emission of the lighting appliance, according to the various application requirements.
Correct lighting must ensure, in the field of vision, sufficiently high luminances, which are rationally distributed to allow the perception of important areas, and also details, reducing to the minimum all forms of dazzling effects.
In particular, emergency lamps must guarantee a light flow which is sufficiently intense and concentrated for allowing exits to be easily and rapidly identified, also and above all in cases of danger.
Luminance is the ratio between the intensity of a light source in a certain direction, and its apparent surface seen from the same direction; its value depends on the illumination, the reflection characteristics of the surfaces and the lighting and observation directions.
Illumination, relating to a point of a surface, is defined as the ratio between the light flow which effects an element of the surface around the point, and the area of the element itself; the illumination can be easily predicted and measured by means of a luxmeter or illuminometer, and can therefore be conveniently and easily used for facing technical problems, such as for example the design of a lighting appliance.
The performances of a lamp, in particular an emergency lamp, are normally evaluated by establishing an illumination datum on a work or utilization plane, conventionally consisting of a horizontal surface at a certain distance from the floor.
When the light reaches this work plane directly from the light source, it is defined as having direct lighting, whereas when, on the other hand, the light reaches the work plane after being reflected, even various times, from the walls and/or ceiling of the room, it is defined as having indirect lighting.
Intermediate cases are obviously extremely frequent, in which the light flow arrives on the work plane in direct and indirect percentages which have intermediate values with respect to those indicated above.
Lamps and/or appliances with direct lighting are widely used for the artificial lighting of buildings for civil and industrial use, both as a main light source and as an emergency or safety source.
These lamps generally comprise a hollow body in which at least one fluorescent tube can be housed, connecting it to terminals which allow the electric charge; the body is closed by means of transparent protection screens, which can be disassembled to allow continuous access to the tube and terminals.
Known emergency lamps currently have a light distribution on the work plane which is not particularly uniform and substantially non-homogeneous, also in relation to the relative position of an observer with respect to the lamp.
Furthermore, the illumination is relatively concentrated and not very intense and it is therefore not possible in practice to obtain an acceptable compromise between the light flow intensity and concentration of the beam, important parameters when an emergency situation arises in civil and working environments and substitutive fluorescent lamps must be used for their lighting.
Finally, it is impossible to obtain a functioning flexibility, in the sense that the use of a single lighting device does not allow light beams to be obtained with different openings, suitable for being adopted for different uses and/or applications.
Documents US 2002/0105807 A1 and EP 0 959 296 A2 show a lighting device with a flexible adjustable reflector which provides an adjustable light beam.
An objective of the present invention is therefore to eliminate the drawbacks reported, by providing an optical group with an adjustable light beam which allows the form of the light emission of a lighting appliance to be varied, in relation to the various application requirements, at the same time, guaranteeing illumination on the work plane which is both uniform and concentrated and also sufficiently intense.
A further objective of the present invention is to indicate an optical group with a variable light beam which satisfies the safety regulations in force.
Another objective of the invention is to provide an optical group with an adjustable light beam, which is relatively simple to construct, safe and reliable, using substantially known technologies and relative inexpensive components.
These and other objectives, according to the present invention, are achieved by providing an optical group with an adjustable light beam, according to claim 1 enclosed; further technical characteristics are present in the subsequent claims.
The invention advantageously defines a new optics for a lighting appliance, which offers the possibility of producing different light beams in relation to various regulations of an optical component.
The optical performances remain the maximum, especially with respect to the extremely high efficiency, all regulation conditions.
In particular, the light efficiency, only slightly lower than that obtained with traditional appliances, thanks to the greater versatility, is able to guarantee higher performances under all conditions of use (also for appliances so far reserved for special applications, such as watertight ceiling light fixtures with concentrating optics).
Further objectives and advantages of an optical group with an adjustable light beam, according to the present invention, will appear more evident from the following illustrative and non-limiting description, referring to the enclosed schematic drawings, in which:

figure 1 is a perspective view of a lighting appliance which englobes an optical group with an adjustable light beam, in a first operating position of the reflector, according to a first embodiment of the present invention;
figure 2 is a perspective view of the lighting appliance of figure 1, with the reflector of the optical group in a second operating position, according to the embodiment of figure 1 of the present invention;
figure 3 shows an embodiment of the optical group with an adjustable light beam, with the reflector in a first functioning position, according to the embodiment of figures 1 and 2 of the present invention;
figure 3A is a Cartesian diagram which shows the qualitative trend of the light intensity in the space produced by an optical group according to figure 3;
figure 4 shows a scheme of the optical group with an adjustable light beam, with the reflector in a second functioning position, according to the embodiment of figures 1 and 2 of the present invention;
figure 4A is a Cartesian diagram which shows the qualitative trend of the light intensity in the space produced by an optical group according to figure 4;
figure 5 shows a scheme of the optical group with an adjustable light beam, with the reflector in a third functioning position, according to the embodiment of figures 1 and 2 of the present invention;
figure 5A is a Cartesian diagram which shows the qualitative trend of the light intensity in the space produced by an optical group according to figure 5;
figure 6 shows the qualitative trend of the illumination, in polar coordinates, produced by an optical group with an adjustable light beam, in the various functioning positions and compared with the illumination produced by an appliances of the traditional type, having the same emitted light power;
figures 7, 8 and 9 refer to respective functioning positions of a further embodiment of the optical group with an adjustable light beam, according to the present invention.

With particular reference to figures 1-6 mentioned above, the optical group which produces an adjustable light beam, according to the present invention, is assembled inside lighting appliances (such as emergency lamps) of the type indicated with 8 in figures 1 and 2 enclosed, and essentially comprises two linear fluorescent lamps, indicated with 10 and 11, a specular reflector 12 having a shaped body 5 and a containment structure or lamp-holder 9.
As shown in figures 3-5 enclosed, in a section perpendicular to the axes of the lamps 10, 11, the optical group has a symmetry with respect to the line S passing through the middle point M of the axis K joining the centres C1, C2 of the two fluorescent lamps 10, 11 and perpendicular to the same axis K.
The lamps 10, 11 are situated in fixed positions, whereas the body 5 of the specular reflector 12 is equipped with two side flaps 6, which, as they can be opened and closed (varying their angular position), allow the variation of the light beam; furthermore, each flap 6 effects symmetrical side movements with respect to the respective symmetry axis S of each branch A1, A2 of the body 5 of the reflector 12, which has a profile which has been specifically studied and constructed so as to obtain an optics with ideal behaviour in all configurations of use.
In particular, the body 5 of the reflector 12 consists of a central curvilinear surface consisting of two branches A1, A2, symmetrical with respect to the axis S of the optical group and, as already mentioned, in practice, the variation in the angular position of the flaps 6 allows light beams with different openings to be obtained.
In particular, the position represented in figure 5, with the flaps 6 in a so-called closed position, creates a narrow light beam (diagram of figure 5A), suitable therefore for installations at great heights or in the presence of narrow areas to be illuminated (corridors, warehouses with racks, etc.).
Figure 4 schematically shows a functioning position with the flaps 6 in a partially open position (obtained by means of an approximate rotation of about 12 degrees from the closed position); in this case, the light beam produced is wider than the previous one (diagram of figure 4A) and guarantees excellent performances in installations.
Figure 3 shows a functioning position with the flaps 6 in a completely open position (obtained by an approximate rotation of about 24 degrees from the closed position); in this case, an extremely wide light beam is obtained (diagram of figure 3A), almost identical to that obtained with a traditional lighting appliance, with the same emitted light power.
The performances of the optical group are represented in both the diagrams of the light intensity distribution in the space of figures 3A, 4A, 5A, and also in the polar diagram of figure 6, where the diagrams of the illumination of an appliance of the traditional type are compared with those produced by the optical group according to the present invention, in the various functioning positions.
These functioning specifications are also satisfied by using a production variant with respect to what is represented in figures 1-6 and described above; in particular, with reference to figures 7-9 enclosed, a different mechanical solution is envisaged for varying the geometry of the central area of the body 5 of the reflector 12.
More specifically, instead of envisaging the rotation of the flaps 6 around two specular points with respect to the central axis S, as illustrated in figures 1-6 and described above, a central body 15 is used, suitably shaped, so that, in correspondence with the opposite sides, 16, 17 and 18, 19 respectively, it has relative sides having the same shape as the angular positions of the flaps 6 shown in figures 3-5 and, in particular, the "open" or "partially open" and "closed" positions, respectively illustrated in figures 3, 4 and 5 and corresponding to a diffusing beam geometry (figures 3 and 4 and surfaces of the body 15 indicated with 16 and 19) and concentrating (figure 5 and surfaces of the body 15 indicated with 17 and 18).
The central body 15 is suitably assembled to the body 5 of the reflector 12, for example according to a constructive solution by insertion, according to which the body 15 is kept in position, inside the central seat 25, positioned centrally with respect to the reflector 12, by means of the covering flaps 26, whose lower appendixes are engaged in the cavities 27 of the central seat 25.
The fulcrum, consisting of the central pin 20, connected to the body 15 and rotating inside the interstice defined by the walls 21, 22 (solution illustrated in figure 7), allows the rotation of the same body 15 around the longitudinal axis, according to the direction of the arrow F.
By subsequently rotating the body 15 along the direction F, it is possible to pass from a constructive solution with a concentrating light beam (figure 7, in which the surfaces 17 and 18 of the body 15, geometrically shaped so as to obtain a concentrating light beam, corresponding to the angular positioning of the flaps 6 of figure 5, are positioned above the body 5 of the reflector 12), passing through an intermediate rotation position (figure 8), to a constructive solution with a diffusing light beam (figure 9, in which the surfaces 16 and 19 of the body 15, geometrically shaped so as to obtain a diffusing light beam, corresponding to the angular positioning of the flaps 6 of figure 3 or 4, according to the curvature imparted to the above surfaces 16, 19, are positioned above the body 5 of the reflector 12).
The advantages of this constructive solution, with the same illuminotechnical results reached, mainly consist in the great simplicity for the final user of univocally varying the type of optics; all of this naturally derives from the simplicity of the mechanism adopted, which in turn guarantees an extreme reliability of the product.
In short, by using both the constructive solution with flaps and also the constructive solution with a rotating central body, all the project specifications are satisfied and the light efficiency of the optical group, according to the invention, even if slightly lower than that of traditional lighting appliances, with the same emitted power, thanks to the wider versatility, is able to guarantee higher performances under all conditions of use; in particular the following advantages are obtained:

an average illumination practically the same (+ 1%) as that of lighting appliances of the known type, with the same emitted power, on normal plants;
a much higher illumination (+ 15-21%) than that obtained with traditional lighting appliances, with the same emitted power, on particular applications, in which an extremely concentrated light beam is required.

In practice, it has been affirmed that the optical group according to the invention is particularly advantageous for its great uniformity and illumination area which is obtained and, in particular, for the fact that controlled photometric performances can be obtained.
To conclude, a lighting appliance which comprises an optical group according to the invention, can not only substitute current lighting appliances, in particular suitable for emergency lighting, under all conditions so far considered, but in addition, its use can be extended to applications which have so far been reserved for special appliances (such as for example, watertight ceiling light fixtures with concentrating optics).
The characteristics of the optical group with an adjustable light beam, object of the present invention, are evident from the above description, as also the advantages.
Finally, numerous other variants can obviously be applied to the optical group in question, all included in the novelty principles inherent in the inventive idea. It is also evident that in the practical embodiment of the invention, the materials, forms and dimensions of the details illustrated can vary according to requirements and be substituted with other equivalent technical solutions.

Claims

An optical group with an adjustable light beam, suitable for being assembled inside at least one lighting appliance (8), comprising at least one containment element or lamp-holder (9), which includes at least two light sources (10, 11), situated in fixed positions above a specular reflector (12), which has a symmetry with respect to a central axis (S) passing through the middle point (M) of a segment (K) joining the centres (C1, C2) of said two light sources (10, 11) and perpendicular to said segment (K) and said reflector (12) is positioned below said segment (K), wherein at least two curvilinear surfaces (6, 16, 17, 18, 19) are provided between said two light sources (10, 11) and said two curvilinear surfaces (6, 16, 17, 18, 19) are positioned according to variable and pre-established angular positions in order to obtain light beams with different openings, characterised in that said curvilinear surfaces (6, 16, 17, 18, 19) are situated on the body (5) of said reflector (12) and are fixed to said reflector (12) at two points of the reflector (12), wherein said two points are symmetrical with respect to said central axis (S), and said curvilinear surfaces (6, 16, 17, 18, 19) are able to rotate around said two points of the reflector (12).
An optical group according to claim 1, characterised in that said light sources (10, 11) are linear fluorescent lamps.
An optical group according to claim 1, characterised in that a narrow light beam is created, suitable for installations at great heights or in the presence of narrow areas to be illuminated, when said curvilinear surfaces (6, 16, 17, 18, 19) are in a closed position and have at least one vertex (M) in common.
An optical group according to claim 1, characterised in that said curvilinear surfaces (6, 16, 17, 18, 19) are situated on opposite sides of at least one shaped body (15), which is assembled centrally with respect to said specular reflector (12).
An optical group according to claim 4, characterised in that said shaped body (15) is assembled to said specular reflector (12) by means of an insertion system, which allows the rotation (F) of the shaped body (15) around a longitudinal axis, which is perpendicular to said central axis (S).