Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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An improYed eloctronia safety dovice for trucks
The present invention relates to an improved
electronic safety device for trucks.
Practically no commercial vehicles currently in
circulation are equipped with any system capable of
05 warning when the vehicle begins to stray from its
traffic lane.
This is a shortcoming experienced in particular by
the drivers of heavy goods vehicles, who must
travel in all weathers and at any time of day or
10 night, even in conditions of poor visibility (fog,
rain etc.), and often find themselves operating in
considerable discomfort and danger; added to such
environmental factors are the potential risks of
drowsiness or distraction to which the drivers of
15 such vehicles are inevitably sub~ect, and the
consequent possibility that the vehicle may veer
off the road, or at least wander out of its lane.
In a bid to overcome such negative factors, the
applicant has set forth an electronic safety device
20 (disclosed in Italian patent 1,209,078) consisting
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in a sensor fitted to one or both sides of a truck,
directed onto the road surface and serving to
transduce a light input into an electrical signal
that is a function of the intensity of the light
05 source.
The electrical signal from the sensor is fed into a
monitoring circuit of which the respective output
signal becomes significant only when the sensor is
exposed to an intensity of light equivalent, for
example, to the yellow lines which border the hard
shoulders of Italian motorways; the monitoring
circuit is connected to an alarm circuit by which
the driver is warned whenever the sensor produces
an activating signal, i.e. whenever the vehicle
encroaches on the yellow line.
The device in question betrays certain drawbacks in
operation, however. To ensure efficient response of
the sensor, the driver has continually to adjust
the beam of light that provides the luminous input;
~0 in effect, an inappropriately adjusted source can
render operation of the device ineffective during
daylight or night hours (depending upon the last
adjustment effected), and even to a false warning
signal being triggered by traffic markings painted
on the road surface.
Accordingly, the object of the present invention is
to overcome the drawbacks outlined above through
the embodiment of an improved electronic safety
device which exploits the various featur~s of the
05 arrangement described above, while giving greater
precision in sensing the light input and a more
reliable adjustment of the output signal.
The stated object is realized in an electronic
safety device as characterized in the appended
claims, which comprises a first sensor directed at
the road surface, and a second sensor located in
close proximity to and having the same technical
and operating specifications as the first sensor
and directed likewise at the road surface; the two
sensors are connected to the inputs of a single
comparator circuit, of which the output signal
serves to activate an alarm circuit each time the
sensors generate respective and dissimilar signals
in respunse to different luminous intensities and/
or wavelengths in a beam of light projected toward
and reflected onto the sensors simultaneously from
two different heterochromatic areas of the road
surface corresponding respectively to the bare
surfacing material and to a white or yellow line,
or other specific traffic markings.
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The invention will now be described in detail, by
way of example, with the aid of the accompanying
drawings, in which:
-fig 1 is a block diagram of the electronic safety
05 device disclosed;
-figs 2a and 2b are schematic front elevations
illustrating a part of the device in two different
configurations, one active and the other inactive;
-fig 3 illustrates a road vehicle, in perspective,
fitted with the electronic device according to the
invention;
-fig 4 illustrates a possible embodiment of the
electronic device disclosed, viewed in elevation;
-fig 5 shows the essPntial parts of the electronic
device of fig 4, exploded and in perspective.
As illustrated in the accompanying drawings, an
electronic safety device according to the present
invention comprises a first sensor 1, consisting
for example in a photoconductive cell, positioned
on one or both sides of a motor vehicle 9 (fig 3)
and directed at the road surface 2 (figs 1...3) on
which the vehicle stands.
3 denotes a light source located alongside and
within the operating field of the first sensor 1,
also directed at the road surface 2.
The first sensor 1 is invested by a beam emitted
from the light source 3 and reflected off the road
surface 2, which it transduces into an electrical
signal that is a function of the luminous intensity
05 or wavelength of the light input, these parameters
in turn being influenced by the presence of a white
or yellow line 4 or other specific traffic markings
applied to the road surface 2. The signal from the
first sensor 1 provides the input to a monitoring
circuit 5, of which the output furnishss a signal
capable of activating an alarm circuit 6 whenever
the beam from the light source is reflected from
the lines 4 or other road markings.
In the improved device according to the invention,
use is made of a second sensor 7 positioned in
close proximity to and having the same technical
and operating specifications as the first sensor l;
the second sensor 7 is also directed at the road
surface 2, needless to say.
As may be observed from figs 1, 2, 4 and 5, the
sensors l and 7 are positioned one on either side
of the light source 3, parallel one with the other,
and connected one to each input of a comparator
circuit 8 of which the output pilots the operation
of the alarm circuit 6.
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The comparator circuit 8 might be an integrated
circuit, for example, of which the inputs are in
receipt of the signals from the first and second
sensors 1 and 7; more exactly, the comparator 8 is
05 located between the two sensors 1 and 7 on the one
hand, and the monitoring circuit 5 by which the
alarm circuit 6 is activated, as aforementioned, on
the other.
Activation of the alarm circuit 6 occurs every time
dissimilar output signals are emitted by the first
sensor 1 and the second sensor 7 in response to
different luminous intensities and/or wavelengths
in the same reflected beam of light, to which both
sensors are exposed; the difference in question is
due to the fact that the beam is thrown at one and
the same moment onto two dissimilar heterochromatic
surfaces, corresponding respectively to the bare
road surface 2, and to the white or yellow line 4
or other road marking applied to tha surface (see
fig 2a).
In short, the alarm circuit 6 is activated by the
monitoring circuit 5 whenever a given part of the
beam is reflected back onto the one sensor off the
bare road surface 2, whilst the remaining part of
the beam is reflected back onto the other sensor
off a line 4 or other marking, given that it is a
disparity between the two transduced signals that
causes the comparator 8 to activate the monitoring
circuit 5. Accordingly, as long as the position of
05 the two sensors 1 and 7, hence of the vehicle 9,
remains stably within the confines of the traffic
lane or carriageway, such that a light of uniform
intensity and/or wavelength is reflected back onto
both of the sensors 1 and 7, then identical signals
are returned to the comparator 8 and no activating
signal will be received by the monitoring circuit 5
from the comparator (fig 2b). The advantage of such
an arrangement is that, when the vehicle and the
device pause or pass over road markings other than
lane or carriageway lines 4, e.g. exit arrows or
lines running across the carriageway, the output
signals from the sensors 1 and 7 remain identical
(both sensors exposed to light reflected from the
arrow or the line), and the monitoring circuit 5
receives no signal from the comparator circuit 8 -
capable of activating the alarm circuit 6, which
would serve only to disturb the driver in such a
situation.
The preferred location of an electronic safety
device according to the invention is illustrated in
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fig 3, which shows a truck 9 fitted with two such
devices 100 positioned one at each ~nd of the front
bumper bar 14.
With reference to figs 4 and 5, which illustrate a
05 preferred embodiment of the device, it will be
observed that the sensors 1 and 7 and the light
source 3, consisting in an electric lamp 15, are
mounted to a hollow bracket 12 (shown to advantage
in fig 5). The bracket 12 is embodied substantially
as a cup with a peripheral flanged fixing lip 121,
insertable into a sealed cover 20, and affords an
external, essentially central socket (not visible
in the drawings) for acccmmodation and retention of
the lamp 15, to which electrical power is supplied
by way of contacts 21 coinciding with the socket
and passing through the bracket 12.
122 denotes a threaded outer boss afforded by the
bracket in a position coaxial with the socket, onto
which a collar 22 is screwed to retain the lamp 15.
The collar 22 is also threaded externally, at least
in part, to permit of attaching one threaded end of
a sleeve 17 accommodating an optical assembly 13.
More exactly, the space encompassed by the sleeve
17 accommodates a second sleeve 16 embodied in two
matching halves 16a, 16b disposed on either side of
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a longitudinal median plane of the sleeve itself.
The inner sleeve 16 is held internally of the outer
sleeve 17 by a terminal annular lip not visible in
the drawings, and affords three distinct annular
05 grooves 161 at given points along its own length,
as discernible in fig 5, in which to accommodate a
pair of lenses 131, 132 constituting the optical
assembly 13, and a protective glass 18. The lenses
131 and 132 are positioned nearer to the lamp 15,
whilst the glass 18 (which in practice might be
embodied in any suitable transparent material~ is
accommodated within and in sealed association with
the groove 161 farthest from the lamp 15.
The bracket 12 further comprises two holes located
one on either side of the contacts 21 by means of
which to fix the sensors 1 and 7, which might be
photoresistors or photodiodas, internally of two
cylindrical tubes 23 extending parallel with and
substantially equal in length to the sleeve 17, as
discernible from fig 4.
The provision of the tubes 23 has the effect of
exposing the sensors 1 and 7 only to the beam 31
radiating from the electric lamp 15, focused by the
lenses 131 and 132 and reflected back off the road
surface 2 or the line 4.
The bracket 12 is thus fixed to the underside of
the front bumper bar 14 of the truck 9 in such a
way as to dispose the sleeve 17 and the tubes 23
substantially vertical and aligned in a direction
05 perpendicular to the path followed by the vehicle,
hence to the line 4.
The device as illustrated in figs 1 to 3 can be
completed (as shown in fig 4) by cascading the
alarm circuit 6, or the monitoring circuit 5 (see
phantom line), into a switch 19 and a timer 11.
Thus, selected warning and/or safety systems of the
vehicle 9 can be interlocked to the timer 11, and
in the event that the switch 19 remains closed and
a signal is emitted continuously from the output of
the monitoring circuit 5 or the alarm circuit 6 for
longer than a prescribed period, the systems in
question will be triggered into operation. By way
of example, systems interlocked to the timer 11
might be the hazard warning lights, the brakes and
the ignition/fuel supply circuits of the vehicle 9,
in such a way that operation of the timer 11 causes
the hazard warning lights to flash, the brakes to
be applied and the engine to cut out.
The device according to the invention thus provides
a highly effective and dependable safety mechanism,
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by virtue of using two sensors which, in practice,
control one another; the use of two sensors also
enables a better utilization of the device during
daytime hours ~i.e. in diffused light), without
05 necessarily having to adjust the alarm settingr
Such an adjustment can be made nonetheless, for
example by way of a potentiometer 10 associated
with the monitoring circuit 5, which permits of
selecting the threshold above which the monitoring
circuit 5, in receipt of an output signal from the
comparator circuit 8, triggers the alarm circuit 6
into operation.
