GB2094463A

GB2094463A - Signalling light

Info

Publication number: GB2094463A
Application number: GB8206720A
Authority: GB
Original assignee: Cibie Projecteurs SA
Current assignee: Cibie Projecteurs SA
Priority date: 1981-03-09
Filing date: 1982-03-08
Publication date: 1982-09-15
Also published as: SE8201046L; ES272064U; GB2094463B; JPS57158901A; FR2501336B1; ES272064Y; FR2501336A1

Abstract

A light emitting assembly, particularly a signalling light for an automobile, is of the type having a light source (10) and a reflector (21) or means arranged to emit a beam of light. In order to present a neutrally coloured appearance when extinguished, the assembly includes at least one series (100) of doubly reflecting plane parallel strips (110) arranged in the emission path of the light rays in such a way as to permit all of the rays reflected by the reflector to escape and to serve as a mask against the penetration of the majority of ambient light rays coming from the exterior. <IMAGE>

Description

SPECIFICATION Light emitting assembly for automobiles The present invention relates to light emitting assemblies for automobiles, for example coloured signalling lights.

Such lights conventionally have a light source which generally emits white light and co-operates with a reflector, such as a parabolic mirror, the focus of which substantially coincides with the source and which reflects light rays substantially parallel to a principal direction of emission. In order to obtain the desired colour of the light, a coloured translucent wall which can be formed either by a coloured sphere surrounding the bulb or by a coloured glass forming the front face of the lamp is placed in the path of the light.

Such assemblies are quite satisfactory during emission, that is to say when the bulb is lit, since they emit a light of well-determined colour and intensity. However, because of their construction, they have the disadvantage that they display their own colour and/or internal construction to the outside observer. This is essentially due to the fact that ambient rays coming from any direction are generally free to penetrate to the interior of the lamp where they are reflected twice by the reflector and finally leave the lamp which thus reflects forwards a significant proportion of the ambient luminous flux which strikes it.

The ambient light rays which are thus reflected naturally take on the colour of the wall through which they pass, and are even capable of conveying an image of the object which they encounter. This is why the knwon signalling lights appear coloured to the outside observer. The same applies to certain headlamps equipped with a yellow bulb which allows the yellow colouring to be seen froth the outside when the headlamp is extinguished.

Such a coloured appearance constitutes a marked disadvantage from an aesthetic point of view. It would therefore appear extremely desirable to provide light emitting assemblies for automobiles which have a completely neutral appearance (shining white) when they are extinguished. Such assemblies must be capable of harmonising much better than existing assemblies with all bodywork colours.

It is an object of the present invention to provide such an assembly.

According to the invention, there is provided a light emitting assembly for an automobille comprising a light source, a reflector or dioptric means to reflect light rays received from the source forwards, and at least one series of doubly reflecting, substantially planar parallel strips arranged in the path of emission of the light rays in such a way as to permit substantially all the rays reflected forwards during emission to escape and to serve as a mask against the penetration of the majority of ambient light rays coming from the exterior.

Thus the undesirable reflective effect described above may be practically avoided for the majority of directions of incident and particularly for ambient rays coming from above.

After double reflection on one pair of strips, these strips may permit each of the rays reflected by the reflector to escape. On the other hand, for ambient light, they may serve as a mask to the majority of the ambient rays except for those which have an incident direction substantially parallel to the principal direction of emission, these being reflected in the direction of incidence.

However, these latter rays may only represent a small proportion of the ambient luminous flux capable of entering a light emtting assembly according to the invention since in practice, ambient light, for example sunlight, strikes the assembly from above at a marked inclination.

Preferably the strips are arranged, at least in the upper part of the assembly, at an angle from top to bottom and from back to front.

Alternatively, the strips can be arranged in this way in the upper half of the device, and can be arranged in the inverse direction (that is to say angled bottom to top and from back to front) in the lower part of the assembly.

The dimensions, relative spacing and angling of the strips can be variable. Preferably, however, for an optimum effect the strips project on to a plane perpendicular to the principal direction of emission without marked interruption but also without marked overlapping. Interruption wouid reduce the masking effect in relation to ambient rays, while on the other hand, overlapping could produce the effect of a screen blocking the emitted rays.

The colouring can be given to the light rays in any convenient manner, for example by forming the source from a bulb incorporating the colouring or by surrounding the light source by a coloured sphere or by interposing a coloured translucent wall in front of the light source. Alternatively, the reflecting surface of the reflector means can be covered with a coloured varnish or if dioptric means are employed, these can be coloured.

In another embodiment of the invention, the colouring, instead of being produced by conventional means or by an intermediate translucent wall, can be directly incorporated in the strips which then appear as translucent coloured strips having one single surface which is double reflecting (for example strips of coloured glass of which one surface is aluminised).

When all the strips have the same inclination, it is advantageous to use in the axis of the device a cover for direct light arranged between the light source and the strip assembly.

The invention may be carried into practice in various ways and some embodiments will now be described by way of example with reference to the accompanying drawings in which; Figure 1 is a vertical axial section through a light emitting assembly according to the invention; Figure 1 a shows schematically a detailed view a modified form of construction of the strips; and Figure 2 shows very schematically a vertical axial section through a second embodiment.

The light emitting assembly shown in Figure 1 includes a bulb 10 behind which is arranged a reflector 20, the surface 21 of which is reflective.

The filament 11 of the bulb 10 is roughly at the focus of the reflector 20 whose reflecting surface 21 is in the form of a paraboloid with an axis of revolution AA, this axis being the optical axis of the system. As can be seen from Figure 1 , the rays R emitted by the filament 11 are reflected by the reflector 20 parallel to the axis AA which thus constitutes the principal direction of emission.

A direct light cover 30 in the form of a screen is located in front of the bulb 10 in a plane substantially perpendicular to the axis AA. The reflector has side walls 50 extending forward in such a way as to form a housing which protects all the parts of the assembly. This housing is closed by a front glass 60 which is translucent and has no particular colouring. The glass 60 can be provided with diffusion ribs 61 (only partially shown in the drawing) in a known manner.

The rays R reflected by the reflector 20 are given the required colour by means of a coloured translucent wall 70 which is perpendicular to the axis AA.

The device includes a series 100 of strips 110 which are parallel to each other and are doubly reflecting in the sense that their two plane parallel faces 11 Oa and 1 Oh both act as mirrors. The strips 110 are arranged obliquely from top to bottom and from back to front with reference to the axis AA. They serve to reflect the rays which strike them on one or other of their faces 11 Oa or 1 lOb.

In the illustrated embodiment it is their faces 11 Oa and 11 Ob themselves which are shown as being mirrors, and so the strips are reflective on all of their external surfaces and light rays never penetrate into the strips. As will be seen below, other constructions are envisaged and come within the scope of the invention.

The arrangement of the strips 110 in the illustrated embodiment is such that each of the rays R, after passing through the coloured screen 70, is doubly reflected on an adjacent pair of strips and finally leaves the assembly in the direction R1 substantially parallel to the axis AA. Thus almost all of the rays emitted by the filament 11 and reflected by the reflector 20 finally leave the assembly, the dimensions, angle and spacing of the strips being such that every ray which reaches the assembly of strips 110 by passing between two adjacent strips leaves the device after only two reflections. On emission, only luminous flux in the form of rays, which strike the edge of the strips, which are very thin in themselves, is lost.

On the other hand, for ambient rays which arrive for example in an incident direction DA from a point in the sky, the assembly 100 acts as a mask. For the majority of directions of ambient light, the light rays do not penetrate into the interior of the housing 50, or if they do, they do not emerge from the housing in a significant manner. Only the incident rays having a direction DA very close to the principal direction AA can both enter the assembly and leave it. This only corresponds to a very smali proportion of the ambient ray likely to strike the assembly since, as has been stated, ambient light which comes from the sky or the sun does not generally have a direction close to the horizontal.

Consequently, a light emitting assembly according to the invention emits coloured light when the bulb 10 is lit and, when the bulb 10 is extinguished, appears to the observer to be neutral in colour, i.e. relatively white and shining. This is particularly advantageous to designers.

As indicated above, the coloured translucent screen 70 can be replaced by other means which are known perse for example a coloured sphere suitable enclosing the bulb 10 or a coloured varnish covering the reflecting surface 21. It is also possible to give the desired colour to the transparent strips 110 themselves and to provide the strips with one doubly reflecting surface on their external face which faces towards the globe 60. Figure 1 a shows this arrangement. The strips 110 are made from coloured glassorfrom a coloured transparent plastics material and only the face 110 is given an aluminised coating 112.

Figure 2 shows another embodiment in which the strips 110 are given two opposed orientations symmetrically with reference to the horizontal plane through the axis AA. The strips above the horizontal plane of the axis AA are angled from top to bottom and from back to front whilst, symmetrically, the strips beiow the horizontal plane are angled from bottom to top and from back to front. Such an arrangement results in an assembly analogous to that which has just been described with a series of parallel strips having the same angle, except that if certain ambient light rays can enter the interior (through the lower strips) they cannot leave it (because of the inverse angle of the upper strips). It may be noted that this device as shown in Figure 2 can make it possible to dispense with a direct light cover such as 30.

Although a simple light emitting assembly has been described, it should be understood that the invention can be applied to a more complex assembly having behind one single transparent glass such as 60 a plurality of light sources cooperating with a plurality of reflector elements in order to provide lighting assemblies for numerous functions, which may or may not be compartmentalised. It may be advantageous in this case to provide for one assembly of strips to be used in co-operation with the different basic systems of the light emitting assembly.

In addition, it is possible in a manner which is known per se to make the source co-operate with dioptric means and not with a reflector. In this case a lens (for example a Fresnel lens) may be arranged in front of the source to create the beam for emission. The colouring can then be advantageously incorporated in the lens itself.

Such a construction could be arranged so that no ambient ray can leave the light.

Thus, as stated above, the reflective character of the strips means that when the lamp is viewed from the outside when it is extinguished it has a shining white apperance which may be far more pleasing from the aesthetic point of view.

Claims

1. A light emitting assembly for an automobile comprising a light source, a reflector of dioptic -means to reflect light rays received from the source forwards, and at least one series of doubley reflecting, substantially planar parallel strips arranged in the path of emission of the light rays in such a way as to permit substantially all the rays reflected forwards during emission to escape and to serve as a mask against the penetration of the majority of ambient light rays coming from the exterior.

2. An assembly as claimed in Claim 1 having one single series of doubly reflecting parallel strips, the strips having an oblique direction oriented from top to bottom and from back to front.

3. An assembly as claimed in Claim 1 having two series of strips, namely, an upper series angled from top to bottom and from back to front, and a lower series angled from bottom to top and from back to front.

4. An assembly as claimed in Claim 1 or Claim 2, further including a direct light screen arranged in front of the bulb to prevent light rays from arriving directly on the series of strips without first having been reflected on the reflector.

5. An assembly as claimed in any of Claims 1 to 4, in which light rays from the filament pass through a colouring element before arriving at the series of strips.

6. An assembly as claimed in Claim 5 in which the reflector is coated with a coloured varnish.

7. An assembly as claimed in Claim 5 in which the light rays pass through a coloured transparent wall.

8. An assembly as claimed in any of Claims 1 to 3, in which the reflecting strips are made of a transparent material incorporating a colouring whereby the colour is transmitted to the escaping light rays, and in which the strips are rendered doubly reflecting on their faces which face towards the exterior of the assembly.

9. An assembly as claimed in any preceding claim in which the angle, the dimensions and the relative spacing of the strips are such that they project on to a plane perpendicular to the direction of emission substantially without interruption or overlapping.

10. An assembly as claimed in any of claims 1 to 3, or Claim 9 when dependent on any of claims 1 to 3, further including dioptric means consisting of a coloured lens in front of the source to form the emitted beam.

11. A light emitting assembly constructed and arranged substantially as herein specifically described with reference to and as shown in Figure 1 or Figure 2 of the drawings, or either of these Figures when modified in accordance with Figure 1a.