[0001] The present invention refers to a railroad advance starting light signal, that is,
a signal of a type similar to the conventional one known in the railroad signalisation
technique as a call signal.
[0002] The traditional call signal is constituted by means of two lamps horizontally combined
and usually fixed, on the same pole (or post, as it is called in technical jargon)
that carries the lamps for first class protection signal therebelow. The call signal
is normally off or deactivated; when activated, it projects, in the direction of the
incoming train, two milk-white blinking lights which authorize the train to enter
the station, thereby overriding the relevant protection signal which is disposed in
off-state or stop mode.
[0003] The light signals of this type have many drawbacks.
[0004] One drawback relates to the fact that in case of a burnt-out lamp, the relevant useful
signal cannot be generated; in fact, when a lamp burns out, after a service life no
longer than 700 hours for this type of signal, these known devices are unable to supply
all the same the required information, thereby compromising both the regularity and
safety of the operation.
[0005] Moreover, the known devices result subjected, in a more or less variable extent,
which depends on the constructional characteristics, to the so-called "ghost effect".
The latter is a phenomenon of essentially optical nature by which the optical unit
- intended to emit the light signal by projecting white or otherwise coloured light
- although switched off, is able all the same to project a beam of light following
the input and subsequent reflection of foreign radiations (for example, coming from
artificial sources like railroad or road lamps and lights, signs, natural sources
like sun rays) in the signal-projecting direction. Obviously, an event of such nature
would dangerously prejudice the recognition and interpretation of the signals by the
train's staff.
[0006] The main object of the present invention is to suppress or at least greatly reduce
the above said drawbacks.
[0007] This result has been achieved, according to the invention, by adopting the idea of
making an apparatus having the features disclosed in the claim 1. Further characteristics
being set forth in the dependent claims.
The present invention makes it possible to greatly increase the reliability and thus
the operation safety of this type of signal apparatus and to avoid the onset of the
"ghost effect".
Moreover, an apparatus according to the present invention is relatively simple to
make and cost-effective in relation to the its performance.
[0008] These and other advantages and characteristics of the invention will be best understood
by anyone skilled in the art from a reading of the following description in conjunction
with the attached drawings given as a practical exemplification of the invention,
but not to be considered in a limitative sense, wherein:
- Fig. 1 is an elevation front view of an apparatus according to the invention;
- Figs. 2 and 3 are, respectively, a top view and a side view of the apparatus of Fig.
1 when in use;
- Figs. 4 and 5 show the apparatus of the preceding figures in views similar to those
of Figs. 2 and 3, and without a relevant covering guard; and
- Fig. 6 is an operational electric diagram relating to a matrix which defines an optical
group, said matrix being made up of sectors connected in parallel and consisting of
in-series LEDs.
[0009] Reduced to its basic structure, and reference being made to the figures of the attached
drawings, an apparatus 100 according to the invention comprises a pair of optical
groups, each of which is made up of a matrix 1 of luminous elements or sectors connected
electrically to each other.
[0010] In the example illustrated in the figures of the accompanying drawings, the light
advance starting signal apparatus 100 in question comprises two matrixes of light
elements disposed horizontally syde-by-side.
[0011] Advantageously, each light element or sector 1 consists of one or more light sources
10 connected in series to each other.
[0012] The apparatus 100 provides for using two matrixes 1 with eight sectors in the whole,
five of which are made up of eleven LEDs in-series, and the other three consisting
of ten LEDs also in series, the said sectors being in turn connected in parallel for
a total of 85 LEDs.
[0013] Shown in Fig. 6 is and electric diagram of a matrix with m sectors in parallel, each
of which consists of n LEDs in series. Provided on each sector is a relevant limiting
resistance (R
1, ..., R
m) and n LEDs (D
1,1 ..., D
m,n).
[0014] Each LED may be of white light-type, falling in the "Lunar White" class indicated
by the standard specification BSI 1376, with a typical light intensity of 3.7 cd at
20 mA, and angle of emission of ±6.5° with respect to its optical axis.
The light intensity on the optical axis is higher than 100 cd.
[0015] With reference in particular to Figs. 1-5, the apparatus 100 comprises a containment
structure consisting of a base 2 and a lid 3 protruding frontally (and sideways with
wings 33) so as to define a screen or shield. The containment structure being possibly
made of foamed polycarbonate. The front part 5 of the structure of apparatus 100 is
downwardly inclined by an angle α of about 10°, so as to avoid the reflexes of the
sun light towards the train's staff. On said front part, supported by a relevant fixing
ring nut, are two plano-lenses 8 made of plastic material and which can have the dual
function of protective means and optical filter.
The base 2 is mounted on a corresponding support 4 allowing it to be fixed to a supporting
post or pole (not shown) and which provides for an inlet 6 for relevant power cables
(not shown) to be connected to a terminal block 7 inside the containment structure
of the apparatus 100.
[0016] The matrixes 1 of LEDs 10, moreover, may be supported by a heat sink 9 of finned
aluminum, with consequent advantages from the thermal point of view.
[0017] In place of the above indicated LEDs of "Lunar White" class, LEDs can be used which
project white light with different trichromatic coordinates by using coated glass
or dichroic filters located in front of the LEDs so as to cause the light to take
up the desidered colour.
[0018] A light signal apparatus according to the invention is characterized, as above mentioned,
by a high reliability.
As for the reliability of a signal apparatus according to the invention, comprising
a matrix of LEDs arranged in sectors in parallel, each sector inluding one or more
LEDs in series, experimental tests have shown that this arrangement allows a significant
increase of the reliability and availability of each of the three optical groups (equal
to each other) that form the ligth signal apparatus. The particular embodiment and
technology being used actually bring about a very long average life; by way of non
limiting example, such length can be expected of over 20 years.
[0019] It should be apparent that the maintenance signal systems result therefore economical
as far as the costs and organization of the maintenance activity are concerned.
For example, while the traditional lamps are replaced about 4 times in a year, the
present invention would allow a system to be in operation for over 20 years.
By using a matrix of LEDs or equivalent light sources as above described, it is avoided
to make use of optical components like mirrors, prisms, colour filters or others,
which may alter the optical path and/or the colour of the light rays produced by external
sources and coming back to the observer ("ghost effect").
1. A railroad apparatus for advance starting light signal, that is, a signal of a type
constituted by means of optical groups horizontally combined to project, in the direction
of an incoming train, two milk-white blinking lights, thereby authorizing the entry
of the train into the station, characterized in that it comprises, for each of said optical groups, at least one matrix (1) of luminous
elements or sectors electrically connected in parallel, each luminous sector comprising
one or more light sources (10).
2. Light signal apparatus according to claim 1, characterized in that each light sector comprises at least two sources (10) connected in series.
3. Light signal apparatus according to claims 1 and 2, characterized in that each light sources (10) is made up of one LED.
4. Light signal apparatus according to claim 3, characterized in that the said matrix (1) comprises eight light in-parallel sectors, each of which comprises
at least two LEDs connected in series.
5. Light signal apparatus according to claim 4, characterized in that the said matrix (1) comprises eight light in-parallel sectors, five of which comprise
eleven LEDs connected in series and three of which comprise ten LEDs connected in
series.
6. Light signal apparatus according to one or more preceding claims, characterized in that the said light sources (10) are LEDs of "Lunar White" class of white-light type falling
in the "LunarWhite" class indicated by the standard specification BSI 1376.
7. Light signal apparatus according to claim 6, characterized in that the said LEDs have a typical light intensity of 3.7 cd at 20 mA, and angle of emission
of ±6.5° with respect to their optical axis.
8. Light signal apparatus according to one or more claims 1 to 5, characterized in that the said light sources (10) are LEDs suited for projecting a light of white colour
and associated with filters able to cause the light emitted by the LEDs to take up
a white aspect as provided by the standard specification BSI 1376.
9. Light signal apparatus according to one or more preceding claims, characterized in that it comprises lenses (8), disposed downstream of said light sources (10) to be crossed
by the light of the latter and inclined downwardly to limit the reflexes.