EP0040853B1 - Signal lamp - Google Patents

Abstract

A signal lamp having a light source, a reflector, and a dispersion sheet wherein the dispersion sheet is divided into a plurality of dispersion elements constructed so as to minimize the adverse effect of incident stray light and minimize or eliminate the occurrence of phantom light effect.

Description

The invention relates to a signal lamp with a light source, a light bundle optics assigned to the light source, a diffusing screen for the emerging light, which has scattering elements arranged one above the other, the upper halves of which deflect downward from above or horizontally incident external light, and with the level of the transitions between the Adjacent scattering elements between the light source and the diffusing screen arranged horizontal slats with light-absorbing tops.

Such a signal lamp is already known (DE-A-28 35 808). This known signal lamp serves as a motor vehicle lamp. The individual scattering elements arranged one above the other are formed by lenses with cylindrical surfaces which are arranged essentially symmetrically in the space between adjacent lamellae. The horizontal slats are intended to counteract the formation of phantom light, which is caused by the fact that incident external light, such as flat incident sunlight, is reflected by the signal lamp. Such phantom light can lead to confusion with a signal that is not actually emitted and can thus have serious consequences. However, it can be seen that if the incidence of extraneous light is very shallow, the extraneous light no longer strikes the slats and is absorbed. Although attempts can be made to improve the absorption effect by reducing the distance between adjacent slats and by increasing the depth of the slats in the direction of the optical axis of the lamp, these measures mean at the same time a significant weakening of the signal light emerging in the operating state, which is also absorbed , and thus an undesirably high energy consumption.

For these reasons, in the known signal light, non-reflective transverse strips are provided on the outside of the cover plate at the level of the horizontal slats. The proportion of the incident external light striking these cross stripes cannot contribute to the phantom formation. On the other hand, the transverse strips are arranged in those areas through which the signal light emitted during operation of the lamp does not pass due to the effect of the lenticular scattering elements.

In this way, however, the phantom light suppression can only be improved to a limited extent. In particular, the light-absorbing effect of the top of the slats is not increased. Although in the known design the upper halves of the cylindrical lenses or scattering elements are inclined from above to horizontally incident extraneous light stepping downwards onto the slats, but the lower halves of the cylindrical lenses or scattering elements conversely convert incidently incident external light upwards into a more horizontal one Redirected direction and prevented from hitting the slats. This negates a positive effect of the upper lens halves. For the rest, it is disadvantageous that in the known signal light, transverse stripes have to be attached to the outside of the cover plate, with precise coordination and alignment having to be carried out on the lens and the slats in order to avoid adverse effects.

With a traffic light (traffic light), the phantom light problem is particularly serious. A traffic light must provide unmistakable information so that it can always be clearly ascertained whether a certain color is lighting up or not. The operating state requires a signal light intensity or luminance which is limited at the bottom by a minimum level of conspicuity and at the top by the risk of glare in a dark environment and by the requirement for low energy consumption in a bright environment. Accordingly, traffic lights can not be operated with any brightness to avoid confusion with a comparatively weak phantom light, which is caused by reflections, in particular from flatly incident sunlight on the front of the cover plate, on the interfaces of the scattering elements of the lens, on the mirror surface of the reflector and on the lamp bulb is created. A special feature of a traffic light is the arrangement and function of an upper half-light space and a lower half-space for the observer, which do not overlap, or at least only slightly. These special conditions allow the arrangement of a barge, which is pulled like a roof over the traffic lights in order to shield the traffic light from incident sunlight. However, such a barge does not help against very flat and possibly also laterally incident sunlight.

The invention has for its object to design the signal light of the type mentioned so that the emergence of phantom light is prevented in a simple manner without a corresponding weakening of the signal light has to be accepted, so that the light emits an ideal traffic light.

This object is achieved in that when the signal lamp is designed as a traffic light with an upper half-light space and a lower observer half-space, the scattering elements are designed such that both their lower halves and their upper halves are inclined to deflect incident light from above or horizontally downwards, whereby the distraction is stronger in the upper halves than in the lower halves.

As a result of this design, as is readily apparent, incoming external light is directed to the top of the slats to an increased extent and is thus made harmless by absorption. Even with comparatively large distances between the slats arranged one above the other and with a small slat depth, practically all stray light beams from the upper stray light half-space can be directed onto the upper sides of the slats if the scattering elements are designed accordingly. Only those stray light rays that are incident exactly on the boundary between the stray light half-space and the observer half-space or in an overlap area between the stray light space and the observer space, depending on the use of the luminaire, are not absorbed if they strike parts of the scattering elements that are intended should emit the signal light in the direction of incidence. But even in this case, the phantom light levels are greatly reduced compared to the existing conditions. The emerging signal light is not weakened since it emerges between the slats arranged essentially parallel to one another and is only then deflected by the scattering elements, that is to say is not directed onto the upper sides of the slats. Otherwise, the diffuser according to the invention can be produced with the specially shaped diffuser elements without additional effort.

Appropriate refinements and developments result from the subclaims. The mirroring of the underside of the slats leads to an intensification of the signal light by reducing its absorption, while with the aid of the provided vertical slats the basic idea of the invention is to direct incident external light onto absorbing slat surfaces, also with regard to that inclined with a horizontal component to the optical axis the external light incident on the luminaire is used.

• Figur 1 einen Vertikalschnitt durch die optische Achse der Signaiieuchte,
• Figur 2 einen vergrößerten Teilschnitt aus Fig. 1 mit Streuelementen und den ihnen zugeordneten waagerechten Lamellen unter Fortlassung der anderen Leuchtenteile,
• Figur 3 in einem weiter vergrößerten vertikalen Teilschnitt die Umlenkung eines eintretenden Fremdlichtstrahls durch ein Streuelement auf die Oberseite einer waagerechten Lamelle und
• Figur 4 in einem gegenüber Fig. 1 vergrößerten horizontalen Teilschnitt ein Streuelement in Ausrichtung auf zwei einander benachbarte senkrechte Lamellen unter Weglassung sonstiger Leuchtenteile zur Verdeutlichung der seitlichen Umlenkung eintretenden Fremdlichts auf die senkrechten Lamellen.

The invention and its mode of operation are explained in more detail below with the aid of a schematic drawing. It shows:

• FIG. 1 shows a vertical section through the optical axis of the signal lamp,
• FIG. 2 shows an enlarged partial section from FIG. 1 with scattering elements and the horizontal slats assigned to them, leaving out the other lamp parts,
• Figure 3 in a further enlarged vertical section, the deflection of an incoming extraneous light beam by a scattering element on the top of a horizontal slat and
• 4 shows, in a horizontal partial section enlarged compared to FIG. 1, a scattering element in alignment with two mutually adjacent vertical slats, with the omission of other lighting parts to clarify the lateral deflection of incident light entering the vertical slats.

1, the signal lamp 1 consists of a light source 2, a light beam optics in the form of a reflector 3 with an optical axis 4 and a diffusing screen 5. The optical axis 4 or the horizontal plane passing through it separates the upper half-light space 6 from the lower observer half-space 7.

Between the lens 5 and the light source 2, horizontal lamellae 8 are arranged one above the other at regular intervals. These horizontal slats 8 have an absorbent top 9 and a mirrored bottom 10. Vertical lamellae 11 are also arranged between the lens 5 and the light source 2 with uniform intervals. The horizontal slats 8 and the vertical slats 11 are offset from one another or arranged one behind the other in the direction of the optical axis 4, but can expediently be arranged in a common vertical plane with the formation of a grating. Likewise, the lamellae 8 and / or 11 can each be rotated together around the optical axis 4 in order to make a setting depending on the specific application in which the external light or. Phantom light suppression is optimal.

The lens 5 has on its inside scattering elements 12 which extend in the horizontal direction, have a height corresponding to the distance between adjacent horizontal slats 8 and are each aligned with the space between two adjacent horizontal slats 8. The scattering elements 12 are designed in such a way that in their upper region 13 they deflect substantially horizontally incident external light rays downward more than in their lower region 14. This results in the approximately sawtooth-shaped profile of the scattering elements 12. The configuration and arrangement of the scattering elements 12 are opposite the slats 8, which are arranged at a distance h from one another, also result from FIG. 2.

also

3, the point of incidence of an incident light beam L, characterized by the distance b, depends on the deflection Δ. The following applies:

so

The depth b _{L of} an ideal lamella 8 is determined by the point of impact which depends on the incidence height t and which strikes the farthest distance from the lens. A smaller value b _L means that phantom light occurs.

In practical design, you will always strive for a slat depth that is as close as possible to the depth of an ideal slat (b _max ), so that:

Furthermore, the value b _max still depends on the limit of the defined stray light half-space 6, that is to say on the flattest angle of incidence e. Basically, all forms of scattering elements 12 for realizing the invention are possible within the optical condition b _L = b _max .

A mirroring of the underside of the slats is desirable if the natural scattering of the emitted signal light or the illuminating optics is so large that many rays strike the underside of the slats 10. In this case, the mirroring of the underside of the slats 10 leads to an increase in the efficiency of the lamp. At the same time, the underside mirroring and possibly also an intended structuring causes an increase in the depth scatter and side scatter even before penetration of the lens 5, so that the prism angles of the scatter elements 12 can be kept correspondingly smaller. This in turn brings about a reduction in the extraneous light which is already reflected by the scattering elements 12 of the scattering disc 5 and which has a disturbing effect as a scattering disc phantom. This diffusing screen phantom effect is based on the fact that the light beam falling on the diffusing screen 5 from the outside is not only refracted but also reflected.

Dabei sind

• p = Reflexionsgrad
• ₈₁ = Winkel zur Flächennormalen in Medium 1
• e2 - Winkel zur Flächennormalen in Medium 2.

According to Newton, the degree of reflection is angle-dependent and increases with the angle of incidence. The following applies:

Are

• p = reflectance
• ₈₁ = angle to the surface normal in medium 1
• e2 - angle to the surface normal in medium 2.

These considerations can become particularly important for railway signals with clearly transparent (uncoloured) lenses, in which the stray light is not reduced by the coloring of the lens.

In some cases, extreme phantom light suppression is required even with the smallest possible angle of incidence of the stray light. It is also conceivable that the stray light space 6 and the observer space 7 overlap slightly.

In this case in particular, it is advantageous to provide the vertical slats 11 in addition to the horizontal slats 8. The significance of these vertical lamellae 11 for the suppression of phantom light results from the illustration in FIG. 4. Thereafter, each intermediate space between two adjacent vertical lamellae 11 is assigned a scattering element 15 which extends in the vertical direction and which, as shown, is shaped so that it is in its middle Area 16 incident light rays deflected more than in its lateral area 17 to the side on the adjacent flat side of the nearest vertical lamella 11. External light incident through the vertically running and laterally directly adjoining scattering elements 15 is thus directed more intensely onto the vertical lamellae 11 and is thus absorbed and rendered harmless.

The increased phantom light suppression due to this lateral deflection of the incoming extraneous light essentially corresponds to the previously described phantom light suppression by vertical deflection of the incoming extraneous light beams. However, in the case of vertical deflection, the extraneous light beams are to be deflected onto the upper sides of the slats and thus essentially only downwards, two absorbing slat surfaces are available for each vertical diffusion element 15 between two adjacent vertical slats 11, so that FIG. 4 has a symmetrical design shows, in which the deflection takes place laterally to the left in the left area and laterally to the right in the right area. Due to the increased deflection in the central region 16 of the scattering element, the shape of the scattering elements 15 shown results with a vertical incision running essentially in the middle between the adjacent slats 11. Possibly. can, however, also be deviated from the symmetrical design without the advantage of the increased absorption of extraneous light being negated.

With regard to the vertical slats, the considerations for optimal suppression of the phantom light initially only apply to a predetermined direction of incidence of the stray light rays, which are indicated by arrows in FIG. 4. Deviating directions of incidence - as always when the stray light and observer areas overlap - lead to somewhat less favorable or less optimal results.

It may also be desirable to provide the vertical slats with a reflective coating on one or both sides and possibly not to align them parallel to the beam path. Furthermore, the vertical lamellae can also be spatially formed and have side surfaces which run at an angle to one another. This is desirable in the case of signals with large side scatter in order to achieve side scatter on the one hand, but also to reduce the phantom light caused by the lens itself due to the large prism angle. It is also conceivable to arrange both vertical mirrored slats and vertical absorbing slats one behind the other.

Depending on the given light distribution, the optimal solution for different directions of incidence must be checked in order to obtain the optimal overall solution.

The illuminating optics can consist of a reflector such as reflector 3 in FIG. 1. This is usually the case with signal lights in road traffic. The optics can also consist of a lens or a lens system, as is often the case with railway signal lights. Combinations of reflector and lenses are also possible.

The lens 5 can be flat or curved. The horizontal scattering elements 12 and the vertical scattering elements 15 can be repeated periodically over the entire spreading disc 5. However, the individual scattering elements can also be designed differently, or groups of the same type of scattering elements are formed which cover the scattering disc 5. Furthermore, training is also possible in which groups are repeated in which the individual scattering elements are designed differently in a typical manner.

In all these cases, the lamellae are advantageously aligned with the special arrangement of the scattering elements. With lower demands on the suppression of stray light but also with a special design of the light-bundling optics, the described optimization principle can be interrupted in such a way that individual scattering elements or groups of scattering elements remain without associated slats.

The horizontal scattering elements 12 and the vertical scattering elements 15 can be provided in mutual superimposition on a single side of the lens 5 or on the one hand on the front and on the other hand on the back of the lens 5, as shown in Fig. 1. Furthermore, it is also possible to work with two scattering disks arranged one behind the other, one of which has the horizontal scattering elements 12 and the other has the vertical scattering elements 15.

Claims (9)

1. A signal lamp having a light source, light bundling optics arranges to receive light from the light source, a dispersion sheet (5) carrying dispersion elements (12) lying one above the other and being arranged such that in their upper zone horizontal incident stray light as well as from above incident stray light is bent down, and strips (8) horizontally arranged between the light source and the dispersion shield, spaced from one another, having their upper sides light absorptive with respect to incident light, characterized in that the said signal lamp is a traffic lamp the space in front thereof being divided into an upper disturbing hemisphere (6) and a lower observer's hemisphere (7), the said dispersion elements (12) being constructed such that by their upper zones (13) as well as by their lower zones (14) stray light « L which contacts them from above or in the horizontal direction is bent downward, the light which contacts the upper zone (13) of the dispersion element being bent more severely downward than the light which contacts the lower zone (14) of the dispersion element.

2. A signal lamp of Claim 1, characterized in that the under sides (10) of the horizontal strips (8) are rendered light reflective.

3. A signal lamp of claim 1 or 2, characterized in that the dispersion sheet (5) in the horizontal direction also is divided into dispersion elements (15), that vertical strips (11) are arranged at the transition between laterally adjacent transition elements (15), and that the dispersion elements (15) are arranged such that light incident in the side direction at various points is bent differently severe in lateral direction.

4. A signal lamp of Claim 3, characterized in that the central zone (16) of the dispersion elements 15 bends light laterally to a degree greater than light is bent which contacts the side zones (17), of the dispersion elements (15).

5. A signal lamp of Claim 3 or 4, characterized in that the vertical strips (11) have a light-absorptive surface.

6. A signal lamp of Claim 3 or 4, characterized in that one or both sides of the strips (11) have a light- reflective surface.

7. A signal lamp of any of Claims 3-6, characterized in that both lateral surfaces of the vertical strips (11) are arranged at an angle to one another when viewed in the vertical direction.

8. A signal lamp of Claims 3-7, characterized in that the horizontal strips (8) on the one hand and the vertical strips (11) on the other hand are arranged with axial intervals in the direction of the axis (4) of the light-bundling optics (3).

9. A signal lamp of any of Claims 1-8, characterized in that the horizontal strips (8) and/or the vertical strips (11) are adjustable in a sloping direction by means of swivelling about the axis (4).

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