TECHNICAL FIELD

The present invention relates to rail signals.

BACKGROUND

Illuminated rail signals are used to communicate with the drivers of trains and trams travelling along track (the permanent way). Such rail signals are placed close to the track to which they relate, and as the driver approaches the signal, the viewing angle and visible light intensity change.

SUMMARY OF THE DISCLOSURE

According to the present disclosure, there is provided a rail signal and a rail signalling system as set forth in the appended claims.

According to a first aspect, there is provided a rail signal having a rail signal lamp with a lens assembly comprising: a light emitter panel having an inner panel portion and a surrounding outer panel portion, wherein the inner panel portion is provided with an inner plurality of light emitters and the outer panel portion is provided with an outer plurality of light emitters, and a lens plate covering at least the outer panel portion and provided with a plurality of lens elements aligned with light-emitters in the outer panel portion, wherein the lens assembly provides light from the outer plurality of light emitters with a narrower divergence than the light from the inner plurality of light emitters.

According to a second aspect, there is provided a rail signalling system comprising a plurality of rail signals according to the first aspect and a control system for controlling the rail signals.

The lens plate may be provided with an aperture aligned with the inner plurality of light emitters.

The lens plate may be provided without lens elements aligned with the inner plurality of light emitters. The lens plate may be provided with a diffusion region (diffusion plate portion) aligned with the inner plurality of light emitters.

The lens plate may be provided with a lens element corresponding with each of the light emitters of the outer plurality of light emitters.

The lens elements may be spaced apart on the lens plate.

The rail signal may comprise a lens plate mask extending across the lens plate and provided with an inner aperture aligned with the inner panel portion and a lens element aperture aligned with each lens element of the lens plate.

The lens plate mask may be provided with a diffusion region in the inner aperture.

The inner panel portion may be offset away from the emission direction of the light emitters with respect to the outer panel portion.

The rail signal may comprise a cover spaced apart from the lens assembly and positioned for light from the lens assembly to pass through the cover.

The cover may be configured to absorb at least 75% of light in the range 100nm to 400nm. The cover may be configured to absorb at least 90% of light in the range 100nm to 400nm.

The cover may be configured to scatter a first portion of the light from the lens assembly and to transmit a second portion of the light without being scattered or absorbed, and the second portion is 25%-75% of the intensity of light from lens assembly.

Light emitters of a single colour in the inner panel portion may be arranged in a ring or are arranged in a concentric pattern or rings.

The outer panel portion may be annular and the inner panel portion may concentric with the outer panel portion.

The light emitters may be light emitting diodes.

The light emitters may be red, green and yellow light emitters. DESCRIPTION OF THE DRAWINGS

Examples are further described hereinafter with reference to the accompanying drawings, in which:

• Figure 1 shows a three-dimensional view of a rail signal having two rail signal lamps;

• Figures 2A shows a three-dimensional view of a rail signal lamp of Figure 1 ;

• Figures 2B and 2C show orthogonal, cut-away views through a rail signal lamp of Figure 2A;

• Figure 3 shows an exploded view of a lens assembly of the rail signal lamp of Figure 2A, including a lens plate;

• Figures 4A to 4D show a three-dimensional view, projection views and an enlarged cut-away view of the lens plate of Figure 3;

• Figures 4E and 4F show projections views of further lens plates;

• Figures 5A shows a three-dimensional view of a further rail signal lamp;

• Figure 5B shows an exploded view of a lens assembly of the rail signal lamp of Figure 5A; and

• Figures 6A and 6B show front views of inner light emitters of a lens assembly.

DETAILED DESCRIPTION

Like reference numerals refer to like elements throughout. In the described examples, like features have been identified with like numerals, albeit in some cases having one or more of: increments of integer multiples of 100; and typographical marks (e.g. primes). For example, in different figures, 110 and 210 have been used to indicate a rail signal lamp.

Figure 1 shows a three-dimensional view of a rail signal 100 having two rail signal lamps 110 mounted on a back board 102.

Figures 2A to 2C show further views of one of the rail signal lamps 110, which have a lens assembly 120 with an inner lens assembly portion 120A and an outer lens assembly portion 120B, a cover 112, a visor 114 and a signal lamp back 118. Figures 2B and 2C respectively show views cut-away along planes through the lines B-B and C-C in Figure 2A. The visor 114 shields the lens assembly 120 from sunlight. The cover 112 shields the lens assembly 120 from rain exposure. The signal lamp back 118 may have control electronics and a heat sink. Figure 3 shows an exploded view of the lens assembly 120, having a backing panel 122, a circuit board (light emitter panel) 124, a light emitter mask 126, a lens plate 140 having lens elements 142, a lens plate mask 130, and fixing elements 120F (e.g. screws, nuts and screw receiving features) for assembly of the lens assembly.

Figures 4A to 4C respectively show a three-dimensional view, a front view, and a side view of the lens plate 140. Figure 4D shows an enlarged cut-away view along the line D-D shown in Figure 4B.

The circuit board 124 is provided with light emitters 128 for emitting light through the lens plate 140. Indicative light emitters 128 are shown in Figures 2B and 2C. Inner light emitters 128A are arranged in an inner region 124A (e.g. central region) of the circuit board 124 (circuit board inner region), and outer light emitters 128B are arranged in an outer region 124B (e.g. a concentrically arranged ring region around the central region) of the circuit board 124 (circuit board outer region) extending around the inner region. For example, there may be 120 outer light emitters 128B, e.g. 40 light emitters of each of three different colours.

The lens plate 140 has a planar section 140P and lens elements 142. In the illustrated lens plate 140, the lens elements 142 are provided in an outer region 140B corresponding with the outer region 124B of the circuit board 124 on which the outer light emitters 128B are provided, and no lens elements are provided in an inner region 140A corresponding with the inner region 124A of the circuit board on which the inner light emitters 128A are provided.

The divergence of light LA from the inner light emitters 128A that is emitted from the lens assembly 120 and transmitted directly through the (optional) cover 112 is substantially greater (e.g. at least 15° either side of the central axis A) than the divergence of the light LB, LB1 from the outer light emitters 128B (e.g. up to 10° either side of the central axis A, e.g. 3° or 7°) that is emitted from the lens assembly and transmitted directly through the cover. The divergence is the angular range over which a beam has at least 50% of the intensity of the peak intensity of the beam. The divergence of the light LA from the inner light emitters 128A that is emitted from the lens assembly 120 and transmitted directly through the (optional) cover 112 may be at least twice the divergence of the light LB1 from the outer light emitters 128B that is emitted from the lens assembly and transmitted directly through the cover (i.e. without being scattered by diffusion), and may be at least four times as divergent. By the light LB from each outer light emitter 128B being narrowly divergent, the combined light from the outer light emitters provides a beam that is visible at a great distance (e.g. at least 400m), when the driver is close to the central axis A of the rail signal lamp 110. However, the rail signal lamp 110 is typically located to one side or above the rail track, and as the driver approaches the rail signal lamp, his viewing angle will move away from the central axis, beyond the narrow divergence, and the intensity of light transmitted to the driver from the outer light emitters 128B will decrease. By having a widely divergent beam, the light LA from the inner light emitters 128A remains visible to the driver when the driver is close to the signal, and at a large viewing angle relative to the central axis A (e.g. up to 45° away from the central axis). When the driver is at a great distance, close to the central axis A, the dominant light from the rail signal lamp 110 that the driver views is from outer light emitters 128B, and will appear to the naked eye as a small bright disc (i.e. the lower intensity inner region will not be distinguishable). When the driver is at an intermediary distance from the rail signal lamp 110, at an intermediary angle from the central axis A, the intensity of the light the driver receives from the inner light emitters 128A is greater, the intensity of the light the driver receives from the outer light emitters 128B is reduced, and the rail signal is again visible as a bright disc. When the driver is close to the rail signal lamp 110, at a large angle to the central axis A, the driver may receive little or no light that is directly transmitted through the (optional) cover 112 from the outer light emitters 128B, the light that the driver receives from the inner light emitters 128A is further increased, and again the rail signal is visible as a bright disc.

Locating the more divergent inner region of the lens assembly 120 within the outer region of the lens assembly, enables the driver to maintain their gaze at a single viewing location (the centre of the lens assembly) and to observe a relatively constant appearance (to the naked eye) of a rail signal, as the driver approaches the rail signal lamp 110 along a range extending from a great distance (e.g. at least 400m) until close to the rail signal lamp, and at a substantial angle from the central axis A of the rail signal lamp. Accordingly, separate rail signal lamps for viewing at different distances from the rail signal are not required, the illumination of a rail signal lamp will not extinguish or substantially dim to the naked eye as the driver approaches, and the driver will not be required to change the location of their gaze as they approach the rail signal.

The widely divergent light LB from the outer light emitters 128B is visible from both sides and above and below the central axis A of the rail signal lamp 110. Accordingly a single design of rail signal lamp 110 may be used in left-, right-, upper- and ground-mounted positions, reducing inventory requirements compared with arrangements using separate rail signal lamps for distant and close viewing. The inner region 140A of the illustrated lens plate 140, in Figures 3, 4A and 4B, is a planar transparent inner region. The use of a transparent inner region 140A of the lens plate 140 reduces optical loss in light transmitted through lens plate from the inner light emitters 128A.

Alternatively, as shown in Figure 4E, the inner region 140A of the lens plate 140 may be an inner diffusion region 140A’, for example being a planar inner region provided with a roughened (frosted, etched) surface profile (having a misty/milky appearance) or being formed from a diffusion inducing material (e.g. a material with a misty/milky appearance). The inner diffusion region 140A’ increases the divergence of the light emitted from the inner light emitters 128A.

The inner region 140A of the lens plate 140 may be provided with inner lens elements aligned with the inner light emitters 128A on the inner region 124A of the circuit board 124 (additionally or alternatively to providing the inner diffusion region 140A’), and having different optical powers from the (outer) lens elements in the outer region 140B of the lens plate. The optical power of the inner lens elements provides light emission from inner region of the lens assembly 120 that has a greater divergence than the light emission from the outer region of the lens assembly. That is, the divergence of light from the inner light emitters 128A after passing through inner lens elements in the inner region 140A of the lens plate 140 is greater than the divergence of light from the outer light emitters 128B after passing through the (outer) lens elements 142 in the outer region 140B of the lens plate 140, e.g. being at least twice as divergent.

Alternatively, as shown in Figure 4F, the inner region 140A” of the lens plate 140” may be a provided with an aperture 140A” (e.g. a single large aperture) for alignment with the inner light emitters 128A in the rail signal lamp 110. The use of an aperture in the inner region 140A” of the lens plate 140” minimises optical loss in light transmitted through lens plate from the inner light emitters 128A.

The lens plate may be formed from a transparent acrylic plastic or glass (each of which may optionally be provided with an inner diffusion region).

As shown in Figure 4D, the illustrated lens elements 142R, 142Y, 142G on the lens plate 140 corresponding to light emitters 128B emitting differently coloured light (e.g. red, yellow and green, respectively) have different optical powers, providing light LB from the outer light emitters 128B with similar divergences. For example, the lens plate 140 may have 120 lens elements, having 40 lens elements for each of three different colours of light emitters 128B.

The (optional) light emitter mask 126 is provided between the circuit board 124 and the lens plate 140. The light emitter mask 126 is provided with an aperture 126A for each of the light emitters 128 on the circuit board 124. The light emitter mask 126 reduces reflective scattering of light between the light emitters 128 and the lens plate. The light emitter mask 126 reduces the reflection of stray light laterally between the circuit board 124 and the lens plate 140 from sunlight or train lights falling on the rail signal 100.

The lens plate mask 130 generally covers the outer region 140B of the lens plate 140, having mask apertures 132 for the transmission of light from the light emitters 128. The lens plate mask 130 has outer lens element mask apertures 132B, each corresponding with an underlying lens element 142 for the outer light emitters 128B, and a larger inner mask aperture 132A for the plurality of inner light emitters 128A. The larger inner mask aperture 132A enables the transmission of the more divergent light LA from the inner light emitters 128A.

Alternatively, the lens plate mask 130 may be provided with inner lens element mask apertures corresponding with the inner light emitters 128B, and the inner lens element mask apertures may be wider (larger diameter) than the outer lens element mask apertures.

The lens plate mask 130 partially shields the lens plate 140 from ambient light, reducing reflections from the rail signal lamp, known as “phantom” (e.g. substantially reducing the risk of sunlight or train lights reflecting to the driver from the flat surface of the lens plate between the lens elements 142, reducing signal performance).

The cover 112 is orientated with its perpendicular angled away from central axis A of the rail signal lamp 110, which reduces the risk of sunlight or train lights reflecting to the driver from the cover.

The cover 112 may be a ultraviolet absorbing cover, e.g. absorbing at least 75% (e.g. at least 90%) of perpendicular, non-reflected light in the range 100nm to 400nm. The ultraviolet absorbing cover reduces the ambient ultraviolet light falling on the light emitters 128, which may stimulate undesirable visible emission from the light emitters (e.g. by exciting phosphor- containing compounds in a light emitting diode), reducing signal performance. The illustrated cover 112 is (optionally) a tinted cover. The tinted cover 112 partially scatters the incident light passing through the cover (e.g. scattering 10% of the intensity of light from lens assembly 120). The tinted cover 112 may transmit 25%-75% of the intensity of light from lens assembly 120 without scattering or absorption (e.g. the tinted cover may transmit approximately 50% of the light). The tinted cover 112 may also absorb incident light (e.g. absorbing 40% of the intensity of light from lens assembly 120).

The tinted cover 112 causes scattering of part of the narrowly divergent light LB from the outer light emitters 128B, with the scattered light LB2 having a much greater divergence than the transmitted light LB1 that has not been scattered (or absorbed). The scattered light LB2 provides bright scattering centres 112S that are visible on the tinted cover 112, as shown in Figures 1 and 2C. The larger divergence enables the scattered light LB2 to be visible to the driver when close to the rail signal lamp 110, e.g. where the driver is at a large angle to the central axis A and may receive little or no light unscattered light LB1 from the outer light emitters 128B. Accordingly, the scattered light LB2 increases the illuminated area of the rail signal lamp 110 that is visible to the driver, increasing close-viewing signal performance, and which can provide the naked eye with the appearance of a larger bright disc, by blending with the light from the inner light emitters 128A. Additionally, the scattered light LB2 from the outer light emitters 128B increases the total light from the rail signal lamp 110 that is visible to the driver.

The cover may be formed from a polycarbonate plastic and may be provided with coatings, e.g. an ultraviolet absorption coating, an anti-reflection coating, and an antifog coating.

The light emitters 128 may be light emitting diodes (LEDs), for example LEDs of different colours (e.g. red, yellow and green LEDs).

Figures 5A shows a cross-sectional view of a further rail signal lamp 210. Figure 5B shows an exploded view of the lens assembly 220 of the rail signal lamp 210 of Figure 5A, having a backing panel 222, a composite circuit board (light emitter panel) 224, a light emitter mask 226, a lens plate 240 having lens elements 242, a lens plate mask 230, and fixing elements 220F (e.g. screws, nuts and screw receiving features) for assembly of the lens assembly.

Similarly to the lens plate 140” of Figure 4F, the lens plate 240 is also provided with an aperture 240A” (e.g. a single large central aperture) aligned with the inner light emitters 228A. A diffusion region 234 is provided in the inner mask aperture 232A of the lens plate mask 230. The diffusion region 234 may be a material with a roughened (frosted, etched) surface profile (having a misty/milky appearance) or may be formed from a diffusion inducing material (e.g. a material with a misty/milky appearance).

Providing the diffusion region 234 on the lens plate mask 230 increases the separation between the diffusion region and the inner light emitters 228A, compared with providing the diffusion region 140A’ on the lens plate 140’, as shown in Figure 4E. The increased separation between the diffusion region 234 and the inner light emitters 228A provides a more uniform appearance of the light LA from the inner light emitters 228A that is scattered by the diffusion region 234. Providing the diffusion region 234 on the lens plate mask 230 instead of providing the diffusion region 140A’ on the lens plate 140’ enables the lens plate 240 and lens assembly of the rail signal to be manufactured with reduced manufacturing complexity.

The composite circuit board (composite light emitter panel) 224 has a separate circuit board inner region 224A (e.g. central region) and circuit board outer region 224B (e.g. a concentrically arranged ring region around the central region), respectively provided with inner light emitters 228A and outer light emitters 228B. The circuit board inner region 224A is offset away from the emission direction of the light emitters 228 (e.g. offset along the central axis A) with respect to the circuit board outer region 224B.

Offsetting the circuit board inner region 224A away from the emission direction of the light emitters 228 increases the separation between the inner light emitters 228A and the diffusion region 234 provided on the lens plate mask 230 (or similarly with respect to the diffusion region 140A’ on the lens plate 140’, for the lens plate of Figure 4E). The increased separation between the diffusion region 234 (or 140A’) and the inner light emitters 228A provides a more uniform appearance of the light LA from the inner light emitters that is scattered by the diffusion region.

Figures 6A shows an arrangement of inner light emitters 128A (128AY, 128AG, 128AR) arranged in the inner region (e.g. central region) of the circuit board 124. The inner light emitters 128A may be light emitters of different colours, e.g. red, yellow and green light emitters 128AR, 128AY, 128AG. The arrangement of light emitters of a single colour in one or more rings RING increases the range of viewing distances over which the naked eye may perceive the illuminated inner light emitters 128A (e.g. of a single colour) as a single bright disc. Figure 6B shows an alternative arrangement, in which the inner light emitters 128A are arranged in rings, with different colours arranged in a concentric pattern, with light emitters of a single colour arranged in a different diameter ring(s) and a central disc.

A plurality of rail signals 100 may be used in a rail signalling system (not shown), being controlled by a control system (e.g. the system controlling the movement of trains across a rail network).

The figures provided herein are schematic and not to scale.

Throughout the description and claims of this specification, the words “comprise” and “contain” and variations of them mean “including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

The reader's attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.