EP0678703A1

EP0678703A1 - Light for motor vehicles comprising a reflector including a plurality of reflecting areas

Info

Publication number: EP0678703A1
Application number: EP95104631A
Authority: EP
Inventors: Giuliano Cossetti
Original assignee: Seima Italiana SpA; Automotive Lighting Rear Lamps Italia SpA
Current assignee: Marelli Automotive Lighting Italy SpA
Priority date: 1994-04-20
Filing date: 1995-03-29
Publication date: 1995-10-25
Anticipated expiration: 2015-03-29
Also published as: ATE185412T1; IT1267221B1; ITUD940064A1; ITUD940064A0; EP0678703B1; DE69512556D1

Abstract

Light (10) for motor vehicles which comprises a container body (11) containing one or more reflectors (12-112) defining specialised sectors having specific functions, each reflector (12-112) having at least one incandescent lamp (14) associated with a lamp holder (15), the reflector (12-112) cooperating at its front with an outer transparent element (13), the reflector (12-112) being defined by a plurality of concave or convex reflecting areas (16-116) distributed substantially evenly on a surface of the reflector (12-112), the reflecting areas (16-116) being visible through the outer smooth transparent element (13) as a mated plurality of apparent luminous images (19).

Description

This invention concerns a light with lens-bearing reflector for motor vehicles, as set forth in the main claim.
The light according to the invention employs as its luminous sources common lamps of a type with an incandescent filament which cooperate with a reflector associated with an outer transparent element.
The state of the art commonly employs lighting devices and luminous signalling devices, which include a plurality of specific compartments for the individual functions and which employ concentrated luminous sources consisting of incandescent lamps.
These devices differ from each other by the specific functions which they are called upon to perform on the motor vehicle, so that they can be divided at least into lighting devices, which can be identified as front headlights, and signalling devices, which are substantially grouped together in the tail lights.
The lighting devices or front headlights have the purpose of concentrating their light in well defined areas on the road in front of the vehicle, and their main purpose is to illuminate but not to be looked at since the light which they emit is, by definition, dazzling or at least very strong.
These headlights have to illuminate in a homogeneous manner a desired surface at a desired distance and deliver a luminous beam of many hundreds or thousands of "cd".
The signalling devices, instead, are normally grouped in the tail lights and have the purpose of providing specific information for other users of the road who are normally in a rear position.
Whereas the lighting devices have to meet parameters relating to a minimum value of emitted luminous intensity, the signalling devices have to meet parameters relating to minimum and maximum values of emitted luminous intensity since their individual signalling functions have to be able to be observed even for long periods by a user who is in a rear position without that user becoming disturbed.
The above shows that each function installed on the vehicle has to meet very precise regulations as regards colours and intensity of the light emitted, and therefore it could even be stated that the lights performing the same functions are all the same as each other.
In fact, the lights which perform the same function differ from each other only as regards their shapes, which are specific for each vehicle, and as regards the distribution of the functions and therefore of the specific colours within a light.
All the above represents a restriction unwelcome to stylists, who instead would prefer to introduce on each new model of a motor vehicle something new, different and innovatory, etc., even on the tail lights or signalling devices.
One embodiment has already been applied which provides for the use of a light equipped with a plurality of continuous parallel cylindrical lenses positioned on the reflector, the luminous beam of which is defined in cooperation with a plurality of continuous cylindrical lenses positioned at a right angle to those on the reflector but provided on the outer transparent element.
This embodiment has given satisfactory results to the extent that it is considered as a reference point by stylists from the point of view of the transparency, even if it involves an evident lack of homogeneity when the lamp is lit.
Some embodiments are also known which are provided above all on the mini floodlights equipped with halogen lamps and employed to light up show cases, displays, shop windows, etc., in which flat or curved facets have been provided on the reflecting surface of the parabolic reflector and have the main purpose of creating a diverging luminous beam which illuminates the objects or environment in a homogeneous manner.
An analogous embodiment has also been applied to the front headlights of motor vehicles by providing on the inner surface of the reflector zones or strips which are directed in such a way as to reflect the light coming from the lamp in very precise directions.
Such embodiments, even though they are satisfactory for front headlights intended to provide illumination, are not satisfactory for signalling devices which are intended instead to be seen and clearly perceived and therefore have to be homogeneous.
In fact it has been demonstrated that by observing one of these front headlights from a certain direction it is possible to see illuminated only a small portion of the reflector, this portion being that calculated to send the light in that direction.
A rear signalling function requires instead that the whole surface of the specific compartment should be illuminated in a homogeneous enough manner in every direction of observation within the horizontal and vertical angles of visibility laid down by the regulations, while providing at the same time the photometric services distributed according to a determined curve within the same field of visibility.
It is also possible to note that one of the characteristics which differentiate a front headlight substantially from a tail light is the solid angle which delimits the field of visibility of the emitted light and which, especially on the horizontal plane, is aligned on the reference axis and forms a total angle of about 20° for the front headlight, whereas it forms an angle of about 90° or more for a rear signalling function.
Recent times have seen the beginning of the use of miniaturised lamps, discharge lamps or neon lamps or even light emitting diodes as luminous sources for the signalling devices.
These luminous sources provide the ability of making signalling devices which, while ensuring the performance required by the regulations, provide the capability of obtaining new aesthetic effects with more homogeneous and brilliant illuminated surfaces by means of a plurality of punctiform luminous sources distributed, for instance, on a plurality of longitudinal and/or transverse lines.
These embodiments, however, entails some drawbacks.
In the case of the light-emitting diodes, for instance, the luminous sources provide a luminous flow which is about one quarter to one fifth of that of a traditional incandescent lamp.
In order to achieve an overall luminosity comparable to that of incandescent lamps and to comply with the specific regulations regarding luminosity, it is necessary, therefore, to install a great number of the light-emitting diodes. This makes that embodiment uncompetitive from an economical point of view, and moreover it is necessary to take account of the fact that, if some of these light-emitting diode are broken, it is necessary to replace the plate to which all the light-emitting diodes are soldered, with the resulting increase of cost for the user.
The present applicants have therefore tackled the problem of embodying a luminous signalling device for motor vehicles which meets the aesthetic requirements of stylists and which provides, when switched off, an image of transparency and richness and, when switched on, a brilliant and homogeneous image over the whole field of visibility laid down by the regulations, and which uses traditional incandescent lamps as a luminous source.
At the same time the applicants have set themselves the task of embodying a tail light which provides the photometric performance required by the laws in force for every function included in the light, and, in this connection, have designed, tested and embodied this invention.
This invention is set forth and characterised in the main claim, while the dependent claims describe variants of the idea of the main embodiment.
The invention concerns a tail light for motor vehicles which has a modest cost and is characterised by an optical and aesthetic effect which can be likened to that achieved by using a plurality of punctiform or almost punctiform luminous sources of a light-emitting diode type or miniaturised type, for instance.
The tail light according to the invention has a luminous source consisting of an incandescent filament lamp positioned in cooperation with a reflector.
According to the invention the reflecting part of the reflector for each single function included in the tail light is defined by a plurality of small surfaces having very various forms and dimensions and defined here, for the sake of simplicity and brevity, as lenses suitable to combine in a figure the presence of a mated plurality of luminous sources, thus achieving the desired optical effect.
These lenses may be concave or convex and their geometry has been planned so that every apparent luminous image has a desired luminous intensity, as regards quantity and distribution, in the specific working area.
According to the invention these lenses may be provided on the inner or front surface of the reflector or on the outer or rear surface of the reflector.
In the latter case the reflector will therefore be made of a transparent material.
The concave shape of the reflector may be of a parabolic type but can also take on any different shape, seeing that it acts only as a support for the single reflecting surfaces or lenses, which are calculated individually as regards shapes and sizes.
This reflector is associated with an outer transparent element, which either has the normal specific colours, or a component of those colours, for the individual functions, such as red for the position light, the stop light and the rear fog light, or else orange for the direction indicator lights, or colourless for the reversing lights, or is of an obscured type, in which case the colours of its particular signalling function can be seen only when the light is switched on.
According to the invention the outer transparent element is advantageously, but not necessarily, smooth so as to heighten the transparency, richness and depth provided by the inner reflector. Lines or other decorations may also be included to personalise and/or give a special finish but do not modify the transparency or photometric performance.
According to the invention the lenses are arranged on the reflecting surface of the reflector and are aligned in parallel and/or radial rows in relation to the longitudinal axis of the light.
According to a variant the lenses occupy determined circular sectors on circumferences or parts of circumferences concentric with the lamp.
According to other possible variants the lenses can be aligned according to the outer profiles of the individual compartments or specialised sectors for the specific functions included in the tail light.
According to the invention the individual lenses can take up the whole sector individually allotted to them and provided by dividing the reflector into a plurality of determined sectors or can have a configuration delineated within their specific sector.
The lenses can be embodied on the reflecting surface of the reflector with a radially constant distance between centres or, according to a variant, with a distance between centres which is variable progressively or in steps from the centre towards the periphery for the purpose of achieving a desired image for each single lens.
The variability of the distance between centres of the lenses can affect only one axis of the reflector or both axes thereof.
The variability of the distance between centres of the lenses can be continuous and progressive along the axis or axes of the reflector or can concern groups of lenses placed side by side, each group including within itself two or more lenses arranged with a constant distance between centres.
Moreover, the ability to vary the distance between centres can be defined in a radial direction.
Depending on the type of image desired of each single lens, the lens can be spherical, toroidal, toroidal-elliptic or embodied according to a complex curve.
Spherical lenses made with substantially equal generating radii measured on the planes containing the axes "x" and "y" of the specific sector are used when it is desired that the distribution of the luminous rays performed by the individual lens should be uniform on the plane of the axis "x" and on the plane of the axis "y".
Toroidal lenses which are made with the two generating radii measured respectively on the planes of the axes "x" and "y" of the specific sector and having different values are used when it is desired to obtain a uniform but differentiated distribution between the two containing planes "x" and "y".
Toroidal-elliptic lenses which are made with elliptic generating lines on the plane of the axis "x" and on the plane of the axis "y" are used when it is desired to obtain a gaussian luminous distribution concentrated at about the reference axis of the lens but with also the sides of the lens affected at the same time according to desired values.
In this case the ellipses may have radii at the sides, relating respectively to the plane "x" and plane "y", which are equal to each other, while the central radius relating to those planes will be equal or different according to the desired distribution of the light on the two planes.
Likewise the radii too at the sides of the lens may be different from each other according to the desired optical effect.
Lenses having complex surfaces determined with a computer by means of specific calculation and simulation programs are used when it is desired to achieve special effects or when the lenses are placed in a particular position in relation to the luminous source.
According to the invention the reflecting surfaces are suitably treated with varnishes based on aluminium or are metallized under vacuum for the purpose of increasing the reflecting power and of providing the tail light with a rich and brilliant appearance.
The attached figures are given as a non-restrictive example and show some preferred embodiments of the invention as follows:-

Fig.1: shows a configuration of the lenses embodied on the reflector of a function associated with the tail light according to the invention;
Fig.2: is a lengthwise section of a first embodiment of a tail light for motor vehicles according to the invention in which, for the purpose of giving an example, the righthand half has convex lenses, while the lefthand half has concave lenses;
Fig.3: show a variant of Fig.1;
Fig.4: show a variant of Fig.2 in which, an example, the lenses on the righthand half are provided on the inner or front part of the reflector, whereas on the lefthand half the lenses are provided on the outer or rear part of the reflector;
Fig.5: shows a partial three-dimensional view of a reflector according to the invention;
Fig.6: shows two variants of the tail light of Figs.1 and 3;
Fig.7: shows another variant of the tail light of Fig.1;
Fig.8: shows another embodiment of the invention, in which the lenses embodied on the reflector are separated from each other;
Fig.9: shows a further variant of Figs.2 and 4, in which the reflector is not of a parabolic type and has a reduced depth;
Fig.10: shows an integral application of the invention in which a part of the lens-bearing reflector is integrated in the lamp-holder.

A tail light 10 for motor vehicles shown as regards one of its functions comprises a container body 11 with a reflector 12 closed at its front by an outer transparent element 13.
The outer transparent element 13 is made of a plastic material of the colour, or of a component of that colour, laid down in the regulations for the function which it has to perform or else is of an obscured type.
The outer transparent element 13 is advantageously smooth so as to enhance the transparency, richness and depth provided by the inner reflector 12.
According to the invention the container body 11 has undergone an inner surface metallisation treatment to enhance the reflecting power of the reflector 12.
An incandescent lamp 14 cooperates within the reflector 12 and is fitted to a lamp-holder 15, which normally holds also the lamps employed for other functions of the tail light 10.
According to the variant shown in Fig.10 the lamp-holder 15 is solidly fixed to a part of the reflector 12, and this part possesses the same characteristics as the remaining part of the reflector 12 so that the normal dark halo is not generated about the lamp 14, but there is a clear continuity.
In this case the lamp-holder 15, which may hold one lamp or a plurality of lamps, has a reflecting part 212, which is a continuation of the reflector 12 and itself too includes lenses 16. This has the result that there is no lack of optical continuity.
According to the invention a plurality of lenses 16 are included on the reflector 12 and are suitable to ensure a distribution of the luminous beam emitted by the filament of the incandescent lamp 14 according to the angles of visibility laid down in the regulations for the specific function to be performed.
These lenses 16 may cover the whole surface of the reflector 12 without a break in continuity.
These lenses 16 may provided on the inner or front part of the reflector 12 as in the case shown in Fig.2 or in the case of the righthand part of Fig.4.
According to a variant shown in the lefthand part of Fig.4 the lenses 16 are provided on the outer or rear part of the reflector 12, which in this case is made of a transparent material.
In this case the metallisation treatment, if included, is applied to the outer surface, referenced with 12a, of the reflector 12, and this metallisation, owing to its transparency, increases the reflecting capability of the reflector 12 towards the inside of the tail light 10.
The transparent material of which the reflector 12 consists may be colourless or may have the specific colour of the individual function of the specific sector.
According to a variant this transparent material of the reflector 12 is made of a colour which is a component of the colour of the specific function, the other component thereof being present on the outer transparent element 13.
The plurality of lenses 16 bring about the formation of a plurality of substantially punctiform apparent images, or luminous zones 19, thus providing the optical effect of independent luminous sources distributed over the whole surface of the specific function performed by that specific sector of the tail light 10.
The geometry of the lenses 16, which may be concave or convex lenses 16 according to the optical effect desired, is such as to achieve a substantially constant luminous intensity for each luminous zone 19 subtended by the various lenses 16.
In a preferred embodiment of the invention the lenses 16 are distributed on longitudinal and transverse lines on the reflector 12.
In the embodiments of Figs.1 and 2, which show a reflector 12 of a parabolic type, the lenses 16 have a variable pitch "p", which increases from the centre towards the periphery of the reflector 12; this configuration enables the presence of luminous images 19 distributed lengthwise with a substantially constant distance between centres "k" to be obtained on the outer transparent element 13.
In the variant of Figs.3 and 4 the lenses 16 are distributed on the surface of the reflector 12 with a constant pitch "p" on the horizontal plane, whereas they are distributed with a variable pitch "p" on the vertical plane.
This enables a plurality of luminous images 19 to be configured on the outer transparent element 13, these luminous images 19 having a distance between centres "k1" progressively decreasing substantially continuously along the horizontal plane of the tail light 10 from the centre towards the periphery of that tail light 10, whereas the distance between centres "k" on the vertical plane remains substantially constant.
With the configuration of Figs.3 and 4 the image of the tail light 10, whether switched on or off, is more homogeneous, even when the direction of observation "X" is inclined in relation to the reference axis 20 of the tail light 10.
The pitch "p" can be made variable also along the vertical plane of the device according to the form of the individual compartment or specialised sector of the tail light 10.
According to the embodiment of Fig.4 each lens 16 has a section of an elliptic-toroidal conformation.
Owing to their elliptic conformation the lenses 16 have a big radius "R" at the central part of the lens 16 and small radii "r" at their sides. This arrangement enables more light to be sent in the direction of the reference axis 20a and less light towards the limits of the field of visibility.
Owing to the toroidal conformation of the lenses 16 according to the invention the radii relating to the vertical plane are greater than, and/or, in any event, different from those relating to the horizontal plane.
Between the lens 16a nearest to the luminous source 14 and the lens 16b farthest from the luminous source 14 the respective radii "R" and "r" become progressively greater.
This makes possible the reduction of the aperture of the reflected luminous beam "α", which changes in the case shown from 40° (plus 20° to minus 20°) to 10° (0 to minus 10°) to obtain a homogeneous distribution from the point of view of the luminous intensity.
The outermost lenses 16 positioned at the periphery of the reflector 12, such as the lens 16b for instance, can be rotated towards the centre of the reflector 12, thus obtaining a reference axis 20b as shown with a line of dashes in the figure, so as to prevent the reflected rays remaining unused owing to the closeness of the containing walls 11 of the reflector 12.
Fig.5 shows a three-dimensional view of a portion of the parabolic reflector 12, on which are convex lenses 16 formed in such a way that the intersection between one lens 16 and the adjacent lenses produces a form of the luminous image 19 which, when seen from the front, can be likened to a square or rectangle.
According to the invention, when the compartments of the tail light 10 have special forms, the form of the lenses 16 can be changed and made like other polygonal geometric shapes such as, for instance, a lozenge, hexagon, etc., as shown in Fig.6 for example.
According to the variant of Fig.7 the lenses 16 are distributed on circumferences or parts of circumferences concentric with the lamp 14.
The single lenses 16 always possess that specific conformation (spherical, toroidal, toroidal-elliptic, complex curve) required for the desired distribution of light.
The lenses 16 therefore have at their horizontal and vertical sections specific radii such that they deflect the luminous rays according to pre-arranged angles.
The conformation of the lenses 16 according to the invention has to comply with not only the regulations but also an energy requirement and an aesthetic requirement.
The light reflected by the lenses 16 in the immediate vicinity of the lamp 14 is greater than that reflected by the more distant lenses 16; because of this, the curves of the lenses 16 in the horizontal and vertical directions are altered from the centre of the light towards the periphery of the same.
This enables the luminous flow emitted by the luminous source to be distributed rationally and makes possible the creation of a homogeneous aesthetic image, when seen from the front, of the specific function which that specialised sector has to perform.
The lenses 16 can also be embodied on the reflecting surface of the reflector 12 in such a way that there are no points of contact between them as in the case of Fig.8 for instance; in this case the lenses 16 take up only part of the parabolic reflecting surface.
The variant of Fig.9 shows an embodiment in which the reflector 112 is of a stepped type and/or of a type having a reduced bulk as compared to the classic parabolic reflector, which is indicated with lines of dashes in the figure.
In this case the inner surface of the reflector 112 is divided into a plurality of sectors or steps, each substantially parabolic, each of which is made to cooperate with a plurality of lenses 116 or with one single lens 116 affecting the whole step, so as to obtain the desired optical effect.
The individual lenses 116 are embodied advantageously according to complex curves, which differ from the lenses which would be formed if they were embodied directly on the allotted parabola portion of the surface of the reflector 112.
According to the invention the incandescent lamp 14 is associated advantageously with a cap 117 (Fig.9) or frontal screen 17 (Fig.2 but not included in Fig.4 for convenience) placed in front of the lamp 14 itself so that from the normal positions of observation the filament cannot be seen.
The cap 117 or screen 17, if moulded of a transparent material, can also act as a possible filter for the orange/green/red etc. colours linked to the specific function of the specialised sector, if the latter covers the whole lamp 14.
As an alternative, the screen 17 or cap 117 may include a component of the colour of the specific function of the specialised sector, while the other component is provided on the outer transparent element 13.
Moreover, frontal refraction lenses 18 (Fig.9) can be embodied on the cap 117 or screen 17 so as to create in turn brilliant luminous zones, thus providing aesthetic continuity and homogeneity for the whole compartment.

Claims

Light (10) for motor vehicles which comprises a container body (11) containing one or more reflectors (12-112) defining specialised sectors having specific functions, each reflector (12-112) having at least one incandescent lamp (14) associated with a lamp holder (15), the reflector (12-112) cooperating at its front with an outer transparent element (13), the light (10) being characterised in that the reflector (12-112) is defined by a plurality of concave or convex lenses (16-116) distributed substantially evenly on a surface of the reflector (12-112), the lenses (16-116) being visible through the outer smooth transparent element (13) as a mated plurality of apparent luminous images (19).
Light (10) for motor vehicles as in Claim 1, in which the lenses (16-116) are provided on the inner (front) surface of the reflector (12-112), this inner surface (metallised) reflecting towards the inside of the light (10) (Fig.4, righthand part).
Light (10) for motor vehicles as in Claim 1, in which the lenses (16-116) are provided on the outer (rear) surface of the reflector (12-112) made of a transparent material, this outer surface (12a) being metallised on its rear towards the inside of the light (10) (Fig.4, lefthand part).
Light (10) for motor vehicles as in Claim 3, in which the reflecting material of the reflector (12-112) possesses at least one component of the specific colour of the specialised function of the light (10).
Light (10) for motor vehicles as in any claim hereinbefore, in which the lenses (16-116) are distributed along longitudinal and transverse rows in relation to the axis of the light (10) and/or of the reflector (12-112).
Light (10) for motor vehicles as in any claim hereinbefore, in which the lenses (16-116) are distributed on circumferences or parts of circumferences concentric with the lamp (14) (Fig.7).
Light (10) for motor vehicles as in any claim hereinbefore, in which the lenses (16-116) embodied on the surface of the reflector (12-112) have a constant pitch "p" along the horizontal plane of the reflector (12-112) (Fig.4).
Light (10) for motor vehicles as in any of Claims 1 to 6 inclusive, in which the lenses (16-116) embodied on the surface of the reflector (12-112) have a progressively increasing pitch "p" along the horizontal plane of the reflector (12-112) (Fig.2).
Light (10) for motor vehicles as in any of Claims 1 to 6 inclusive or as in Claim 8, in which the lenses (16-116) embodied on the surface of the reflector (12-112) have a constant pitch "p" along the vertical plane of the reflector (12-112).
Light (10) for motor vehicles as in any of Claims 1 to 8 inclusive, in which the lenses (16-116) embodied on the surface of the reflector (12-112) have a progressively increasing pitch "p" along the vertical plane of the reflector (12-112).
Light (10) for motor vehicles as in any claim hereinbefore, in which the lenses (116) are embodied on parabolic portions of a reflector (112) formed with steps (112) (Fig.9).
Light (10) for motor vehicles as in any claim hereinbefore, in which the lenses (16-116) have a spherical conformation.
Light (10) for motor vehicles as in any of Claims 1 to 11 inclusive, in which the lenses (16-116) have a toroidal conformation.
Light (10) for motor vehicles as in any of Claims 1 to 11 inclusive, in which the lenses (16-116) have a toroidal-elliptic conformation.
Light (10) for motor vehicles as in any of Claims 1 to 11 inclusive, in which the lenses (16-116) have a conformation embodied according to a complex curve.
Light (10) for motor vehicles as in Claim 13, in which at least one of the horizontal and vertical radii of the toroidal lenses (16-116) increases progressively, lens by lens, from the centre to the periphery of the reflector (12-112).
Light (10) for motor vehicles as in any claim hereinbefore, in which the outer transparent element (13) is completely smooth.
Light (10) for motor vehicles as in any of Claims 1 to 16 inclusive, in which the outer transparent element (13) contains personalising and/or special finishing lines.
Light (10) for motor vehicles as in any claim hereinbefore, in which the outer transparent element (13) possesses at least one component of the specific colour of the specialised function of the light (10).
Light (10) for motor vehicles as in any claim hereinbefore, in which the lamp holder (15) comprises a central portion (212) of the reflector (12).
Light (10) for motor vehicles as in any claim hereinbefore, in which the lamp (14) cooperates at its front with a screen (17) or cap (117).
Light (10) for motor vehicles as in any claim hereinbefore, in which the screen (17) or cap (117) includes frontal refraction lenses (18).
Light (10) for motor vehicles as in any claim hereinbefore, in which the screen (17) or cap (117) is made at least partly of a transparent material coloured with at least one component of the colour of the specific function of the specialised sector.