EP2953833B1 - Light signal - Google Patents

Description

The invention relates to a light signal, in particular for rail-bound traffic routes, with a light source and an optical system for signaling visualization, in particular in a long range and an angled relative to this area.

In principle, light signals serve as signal transmitters or symbol indicators which convey certain information by color and / or shaping of a luminous area, that is to say by the emission characteristic. These are often safety-relevant information that must not be falsified visually or blended by extraneous light. The unwanted lighting up or falsification of a light spot by the incidence of ambient light, for example solar radiation or headlight, is called a phantom effect. In extreme cases, the phantom effect can lead to a false display due to an inadvertent illumination of a light spot or a color shift. Particularly disturbing occurs this effect in the use of LED arrays as a light source, since LEDs can be excited by incident light to shine or LED reflectors are often used rear reflectors.

In addition to the well-known phantom generators, which are foreseeable in the project planning, for example, low sun for signals in east-west orientation, sporadic or unforeseen sources of phantoms, such as vehicle or building lamps, reflections on surfaces, for example on glazed fronts or snowpacks, up. This allows a signal that should be phantom-safe due to the location, be phantom-prone.

The following explanations relate essentially to light signals for the representation of signal terms in rail-bound traffic routes, without the claimed subject-matter being restricted to this application.

In the case of railway signals, it must be ensured that the driver can always recognize this clearly when approaching the signal intended for him. In this case, different route geometries, that is to say even route, curves and / or height differences must be taken into account. In addition to the long-range display, a close-range representation of the signal is required so that the driver can recognize the light signal even if he is directly in front of the signal. In this case, especially at light exit surfaces of the optical system, strong reflections occur, which can lead to the formation of light phantoms and ultimately to dangerous signal terms.

Reflections from extraneous light, especially from sunlight, are generated more intensely at the light entry surfaces and the light exit surfaces of a cover glass and the optical system, for example a Fresnel lens, as well as on components in the region of the light source. In order to reduce the reflections on the surfaces of the cover glass, it is customary to arrange this in an approximately 15 ° -Shrägstellung against the line of sight of the driver.

In general, an attempt is made to minimize the phantom effect by baring, fading, avoiding east-west orientation or by repeating critical signals.

FIG. 1 shows the reflection ratios to be improved caused by indoor fixtures 1 and a lens 2 of a light signal. It can be seen that sunlight 3 impinging obliquely from above on the lens 2 partially reflects 6 and 7 at its outer and inner surfaces 4 and 5. Also the lens 2 penetrating sunlight 3 can at the internals 1 within a Signal housing 8 are reflected at an unfavorable angle as a disturbing phantom light obliquely down 9. The reflected phantom light 6, 7 and 9 superimposes the information to be visualized by a light source 10. The enclosing all components housing 8 also serves to shield at least a portion of the sunlight 3 both inside and outside. Usually, a further portion of the sunlight 3 is shielded by a barge, not shown here, which covers the lens 2 in the upper area.

Out DE 101 07 256 A1 and DE 10 2010 024 381 A1 It is known to use special barges and diaphragms to combat the phantom effect to take the incidence of phantom light as many ways of entry or angle of incidence. For the Signalbegriffsvisualisierung in the vicinity are often lenses or gray colored end glasses, which have a stray segment for near field illumination, or even fiber segments for deflecting a partial luminous flux in the vicinity required. However, this inevitably creates a compromise that leads to the fact that the phantom protective effect requires a high loss of light, so that a light source with a correspondingly high light intensity is required. This increases the heat development and ultimately reduces the life of the light source. Especially with multi-colored light signals, the light intensity may not be sufficient. This in turn increases the cost, since for different requirements, in particular with regard to the light intensity, different variants for the optical system and possibly also for the suitable light source must be realized.

Out US Pat. No. 1,600,239 A1 a light signal according to the preamble of claim 1 is known.

Particularly pronounced light losses occur due to the widespread use of roof-like barges and special end caps. Barges also have the disadvantage that a high wind load is created by the correspondingly stable Signal mast construction must be compensated. Through snow on the barge further signals can be covered. In addition, by the barge, which often surpasses the light exit surface of the signal quite often, the use of self-cleaning light-emitting surface coatings, which require sunlight and irrigation, prevented.

The invention has for its object to provide a light signal of the generic type, in which an impairment of safety and significant loss of light due to the phantom effect are largely avoidable, it being desirable that barges and / or cover glasses are unnecessary.

According to the invention this object is achieved in that the optical system comprises a Fresnel lens whose light entrance surface Fresnel structures and the light exit surface is formed such that each tangent of the light exit surface with respect to an optical axis of the optical system has an angle of ≥ 105 °.

In this way it is achieved that almost all the light reflected on the Fresnel lens light-entry side and light exit side phantom-reflected light is deflected into areas outside the driver's line of sight. Since the Fresnel structures are provided on the light entry surface and thus on the inner surface and not, as usual, on the outer surface of the Fresnel lens, the light exit surface can be smooth and virtually formed without corrugations. This smooth and dirt-resistant outer surface means that a cover glass is no longer required. In addition, the inventive design of the Fresnel lens is sufficiently phantom to dispense with a barge as additional phantom protection can. This results in cost advantages. In addition, the wind load is reduced, so that the signal mast can be produced more cheaply. Visual obstruction of other signals, such as snow or bird nests on the barge no longer occurs. Without Schute is beyond special coating of the smooth outer surface of the Fesnel lens also allows a self-cleaning function. The required irrigation in conjunction with sunlight of the optical outer surface is no longer prevented by a barge.

According to claim 2 it is provided that between the light source and the optical system, a funnel-shaped aperture is arranged. This additional measure improves phantom protection when indoor installations adjacent to or near the light source can lead to light phantoms. In this case, the narrow opening of the funnel-shaped aperture is adapted to the light exit surface of the light source, while the wide opening of the funnel-shaped aperture corresponds to the aperture of the optical system.

Figur 1

eine vereinfachte Darstellung störender Phantomlichtreflexionen,

Figur 2

Phantomlichtreduktion im Signalinneren,

Figur 3

Phantomlichtreduktion durch erfindungsgemäße Formgebung einer Fresnel-Linse,

Figur 4

die Fresnel-Linse gemäß Figur 3 in Seitenansicht und

Figur 5

die Fresnel-Linse gemäß Figur 3 in perspektivischer Ansicht.

The invention will be explained in more detail with reference to figurative representations. Show it:

FIG. 1

a simplified representation of spurious phantom light reflections,

FIG. 2

Phantom light reduction in the signal interior,

FIG. 3

Phantom light reduction by shaping a Fresnel lens according to the invention,

FIG. 4

the Fresnel lens according to FIG. 3 in side view and

FIG. 5

the Fresnel lens according to FIG. 3 in perspective view.

The problem of phantom-generating sunlight 3 has already been described above on the basis of FIG. 1 shown.

The refraction of light within the lens 2 has been included in the Figures 1 and 2 not considered.

FIG. 2 illustrates a way to reduce the phantom 9 caused by the internals 1. For this purpose, a funnel-shaped aperture 11 is provided. The funnel-shaped diaphragm 11 encloses the light source 10 with its narrow opening and widens into the edge region of the inner surface 5 of the lens 2. As a result, the internals 1 can no longer cause phantom light 9. The sunlight 3 impinges on the inner surface of the funnel-shaped aperture 11, is partially absorbed there and reflected several times, so that only outwardly reflected light 12 of extremely low light intensity can result, which also only partially disturbs as phantom light, while the largest proportion in not relevant solid angle is radiated.

FIG. 3 shows another way to effectively reduce the phantom effect. Shown is the cross section of a thin slice of a Fresnel lens 13 in the region of an optical axis 14. The Fresnel lens 13 is formed with Fresnel structures 15 at the light entrance surface and with a smooth light exit surface 16. In this case, an angle between the tangent 17 at this point and the optical axis 14 of 90 ° + α is provided for all points of the light exit surface 16, wherein α ≥ 15 °. In this way, there is a considerable phantom light reduction, since the majority of the inside and outside of the lens 2 reflected light 6 and 7 is no longer emitted in the line of sight of the driver, but in irrelevant solid angle.

FIG. 4 shows a side view and FIG. 5 a perspective view of the Fresnel lens 13. Due to the very substantial phantom light reductions this special shape of the Fresnel lens 13, it is possible, in particular with simultaneous use of the funnel-shaped aperture 11, to dispense with the usual Schutenberdachung the Fresnel lens 13. Also, a cover glass is not required because of the smooth outer surface 16 of the Fresnel lens 13. The outer surface 16 can be formed by special coating quasi self-cleaning, as required for the cleaning effect rain exposure of the outer surface is no longer prevented by a barge.

Claims (2)

1. Light signal, in particular for rail-bound traffic routes, comprising a light source (10) and an optical system for signal aspect visualisation, in particular into a far range and a near range angled relative thereto, wherein the optical system comprises a Fresnel lens (13), the light entry surface thereof having Fresnel structures (15), characterised in that the light exit surface thereof is designed in such a way that every tangent (17) to the light exit surface (16) is at an angle of ≥ 105° relative to an optical axis (14) of the optical system.
2. Light signal according to claim 1, characterised in that a funnel-shaped diaphragm (11) is arranged between the light source (10) and the optical system.

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