Note: Descriptions are shown in the official language in which they were submitted.
117
1 The present invention concerns signal~ ht ~y5 tem~,
most especially those provided along roads and highways. It is
known to provide emergency-phone stations at intervals along the
length of à highway, the emergency-phone stations being distrib-
uted along the length of a communications cable laid along the
length of such highway. Such emergency-phone stations may be
provided with signal-light systems. For example, each emergency-
phone station in a series of such stations may be provided with
a lamp which, from a remote central station, is caused to blink,
to warn drivers that they are approaching the site of an accident,
or the like. An operator at the remote central station selects
which emergency-phone stations are to have their respective lamps
blink, and the power needed to ef~ect blinking of the lamps is
transmitted to the activated emergency-phone stations via a power-
supply line which runs along the communications cable and which
supplies operating power to electrical equipment at such emergency-
phone stations.
The German periodical "ADAC-Motorwelt," Nov. 1976, pp.
30-32, disclosed the use of the emergency-phone sta~ions provided
at intervals along the length of a highway for the generation of
an optical warning action informing drivers of upcoming hazards.
; The optical warning action in question was to be implemented by
blinking the exterior lamp with which each such emergency-phone
station was anyway provided.
In order to increase the pe-rceivability of the blink-
ing action, Federal Republic of Germany published allowed patent
application DE-AS 19 33 436 disclosed the use not of the exterior
lamp anyway provided at such stations, but instead the provision
of each such station with an electronic flash lamp capable of
being flashed at higher brightness levels. Because the flash
17
1 power needed by such flash lamps is greatly in excess of the
power transmittalbe along the power line of the phone stations'
communication cable, it is necessary to provide each station
with a storage condensor, servicing to periodically accumulate
an amount of stored energy adequate to implement a flash.
Even when such storage capacitors are used, so as
to be able to furnish to the flash lamps an instantaneous flash
power vastly in excess of the power level instantaneously trans-
mittable along the available cable, the fact remains that the low
level of transmittable power places severe limits upon the amounts
of flash energy which can be accumulated during the interflash
intervals, especially when one considers that the interflash
intervals must be kept quite short, in order that the flashing
action attract the attention of drivers moving past the flashing
stations at highway speed. For example, in the system disclosed
in the aforementioned DE-AS 19 33 436, each emergency-phone
station is provided not only with storage-capacitor circuitry,
but additionally with signal-evaluating circuitry needed for the
reception and evaluation of signals transmitted along the avail-
able cable for identification of which stations are to have theirlamps flash. Such signal-evaluating circuitry consumes electrical
power which might otherwise be used for flash energy, in a context
where available energy is at a minimum.
~ ccordingly, it is a general obiect of the invention
to provide a flashing-lamp signalling system of the type or having
the characteristics of the type in ~uestion, in which to the extent
possible the energy transmitted after the commencement of actual
blinking action be utilized exclusively as actual flash energy.
In accordance with the present invention, this is
accomplished by providing each flash-lamp station with signal-
~ 0117
processlng ciscuitry and other c~rcuitry which can be disconnected ~romoperattng power after the commencement of actual flashing or b1inking
operation.
According to a broad aspect of the invention there is provided a
Blin~ing-lamp signalling system for use distributed along the length of a
highway, or the like, the blinking-lamp signalling system comprising a
succession of signal-lamp stations each comprising at least one signal-
lamp, transmission circuit means extending along the succession of signal-
lamp stat~ons, the signal-lamp stations being connected at intervals to the
transmission circuit means, a centsal station connected to the transmission
circuit means and including means transmitting to the slgnal-lamp stations
2ower and also code signals identifying which signal-lamp ~tat~ons have been
selected to have their signal-lamps blink, code-signal evaluating means
provided at each signal-lamp station for receiving and interpreting the
code signals, and switchng means provided at each signal-lamp station and
operative after interpretation of the code.signals by the code-signal
evaluating means for automatically disconDecting the code-signal e~aluating
means ~rom power.
T~us, for example, in the presently prefeTTed embodlment of the
invention, the stations are each provided with f~ash lamps and with a code-
evaluator stage which receives a traDsmitted code-signal identifying select-
ed stations and selected blinking schedules for the flash lamps, After each
selected station has registered the ~lash-schedule command pertaining to itJ
the code-evaluator stages of all stat~ons, both the non-selected stations
and the selected stations, are disconnected from power. Each statlon is
provided with an activation stage whlch i~s permanently connected to po~er
~ut draws substantially zero power except when actual flashing action is to
~e initIated and then, after a prolonged period of flashing action, termin-
ated. In the case of the stations not selected for flashing action, all
circuitry in~olved in flashing action is disconnected from power after the
-4-
`` i~;~O~17
commonccmcnt of flashing action at the other, selected stati~ns, with the
exception o~ the act~Yatlon state at eac~ such non-selected station. As a
Tesult, power not destined for conversion into actual flash energy is con-
sumed to a minimum.
The novel features which are considered as characteristic for the
i~n~ent~on are set forth in particular in the appended claims. The inven*ion
itsel~, however, both as to its construction and its method of operation,
together with additional objects and advantages thereof, will be best under-
stood from the following description of speci~tc embodiments when read in
connection with the accompanying drawing.
FIG. 1 schematically represents the stretch of cable between two
manned highway police posts and a success~on of
- ¦a~5 -4a-
0~17
1 emergency-phone stations connected at intervals to 9uch cable;
FIG. 2 depicts the appearance of an exemplary
emergency-phone station, such as peovided at intervals along the
stretch of cable of FIG. 1
FIG. 3 is a schematic block diagram of the flash-
control circuitry provided at each individual one of the
emerqency-phone stations:
FIG. ~ depicts the internal configuration of the rec-
tifier and charger stage G~E of FIG. 3
FIG. 5 depicts the form of the pulse-modulated A.C.
voltage waveform utilized to activate selected series of stations
and to determine the flashing schedules to be implemented at each
station of such series;
FIG. 6 depicts an example of a coding scheme used to
identify which stations are to be activated, and used to identify
which blinking schedules are to be followed; and
FIG. 7, like FIG. 3, depicts the circuitry with which
each station is provided, the stages depicted in FIG. 3 being
depicted in a more simplified manner in FIG. 7, FI&. 7 depicting
additonal circuit components not shown in FIG. 3~
FIG. 1 depicts a succession of emergency-phone sta-
tions, denoted NRSI-NRS22 spaced at intervals of about 2 kilometers
each, between a manned hishway police p~st ZB a~ a location A and
another such post at location B. The manned posts ZB are re~erred
to as central stations, for reasons which will be~ome apparent.
The emergency-phone stations NRSl-NRS22 are connected at intervals
to a communications line which extends between the two manned
posts ZB. The electrical power needed to o~erate the circuitry
provided at the emergency-phone stations is transmitted to sta-
tions NRSl-6 from the central station ZB at location A, to sta-
ll'Z0~17
ti~n~ ~RS17-22 ~m ~he cen~ral sta~ion ZB at locatian R, and ta
~tations NRS7-16 from an unmanned central statlon ZU. The power-
supply lines from the manned stations zs and from the unmanned
station ZU are separate electrical circuits, as indicated by the
gaps between stations NRS6 and NRS7, and between stations NRS16
and NRS17; in contrast, the communications channel to which the
stations NRSI-22 are at intervals connected extends all the way
between the central stations ZB at locations A and B, although
this is not explicitly shown in the drawing, the power-supply
lines being of interest. In certain conventional set-ups of this
type, each power-supply line comprises two pairs of conductors.
One pair of conductors is used to supply A.C. voltage to an ex-
terior li~ht at the emergency-phone station; the other pair of
conductors has been conventionally used to supply A.C. voltage
to a small lamp located in the emergency-phone mouthpiece to
illuminate an indicium identifying the emergency-phone station
by dilometer number, i.e., so that the user of the phone can
inform highway police of his location. In FIG. 1, for the sake
of simplicity, these two pairs of conductors are represented by
2a a single power-supply line.
Likewise, whereas in FIG~ 1 only a single succession
of emergency-phone stations NRSl-22 is depicted, e.g., extending
along one of the two sides of a highway, typically another such
succession of phone stations is provided along the opposite-
traffic-direction side of the highway. Accordingly, in FIG. 1,
e.g. NRS4 denotes two emergency-phone stations, one located at
the side of the highway of traffic travelling in the direction
from A to B, the other at the side of the highway for traffic
going in the direction from B to A; this is indicated by the two,
oppositely pointed arrows in FIG. 1. The emergency-phone sta-
li;~U117
1 tions at both sides of the highway are connected ~o a common
cable, a so-called omnibus line. This cable is laid along only
one side of the highway, and the emergency-phone stations at the
opposite side of the highway are connected to this cable by means
of cross lines.
The transmission of voltage and current for the
flashing-lamp highway signalling system is effected by means of
a phantom circuit. Such phantom circuit may, for example be
formed from the two pairs of conductors used to energize the
aforementioned exterior lights and the aforementioned lights for
the kilometer indicia. The principle of phantom circuits utiliz-
ing center-tapped inductors or so-called phantom transformers is
too well known in the electrical arts to re~uire detailed explana-
tion here.
~ he phantom circuit is used not only to transmit
flash energy to the set of flash lamps with which each emergency-
phone station is provided, but is additionally used to transmit
code signals from the central stations to the various phone sta-
tions. The transmitted code signals serve, first, to identify
which phone stations are to have their flashing-lamp systems
activated, and serve, second, to identify what blinking schedule
is to be followed at each activated station. Either the code
signals are directly transmitted from a manned central station
ZB to the emergency-phone stations, or else they are transmitted
indirectly, first to the unmanned central station ZU and then to
the emergency-phone stations. In the latter case, the code sig-
nals are converted, at the manned central station, into a form
suitable for data transmission, then transmitted via the through-
going communications cable to the unmanned central station, there
converted back into their original form, and then transmitted
0117
~o the emergency-phone sta~ions. The code signals may be constituted by a
series of pulsed A.C. voltage represent~ng data by resort to a plurality of
different voltage amplitudes. The code--signals may additionally be used to
actually supply the operating power to the evaluating circuitry with which
each phone station is provided for the recognition of the cod~-slgnals.
Each emergency-phone station is provided with a flashing-lamp
signalling subsystem comprised of fouT electronic flash lamps BRl-BR4
~cf. FIG. 3). These form parts of the four signal lamps S~l-SL4 (cf. FIG. 2
pro~ided at each phone station. Each set of four signal lamps SLl-SL4 is,
as shown in PIG. 2, provided on an L-shaped bracket structure. At mounted
By a mounting arrangement Ha on the head part KT of the respective phone
s~tation NRS. Structurally, the L-shaped disposition of the four signal
lamps SLl-SL4 serves to shorten the effective lever arm which the mounting
structure for the lamps presents to wind; also, the L-shaped organization
can implement certain display effects explained in my simultaneously filed,
commonly owned Canadian patent applica~ion Serial No. 331,508 entitled
"SIGNAL-LIGHT SYSTEMS, ESPECIALLY FOR A SERIES OF EMERGENCY-PHONE STATIONS
DISTRIBUTED ALONG THE LENGTH OF A HIGHWAY, OR THE LIKE" filed July 10, 1979.
When a series of immediately successive phone stations is selected
for activation, e.g., to warn of an upcoming traffic hazard or the like, in
the preferred form of the invention the first station of the selected series
of consecutive stations flashes only one of its four signal lamps SLl-SL4,
the next, two of its signal lamps, and so forth, to create a subjective
effect of increasing urgency or increasing closeness to the hazard being
warned of.
li20117
1 Depending upon the nature of the hazard involved it
may be appropriate to activate a series of stations at one side
of the highway only, e.g., in the case of a traffic accident or
a traffic jam, or it may be appropriate to activate a series of
stations at both sides of the highway, e.g., in the case of a
localized stretch of fog, a localized region of road-icing, etc.
Tf fox example ~n FI~. 1 the hazard location G is constituted by
a localized region of road-icing, then those stations NRS5-7
which are at the side of the highway for travel in the A-B direc-
tion are activated, and also those stations NRS10-8 which are at
the side of the highway for travel in the B-A direction. As will
be explained further below, each emergency-phone station, or more
precisely the flashing-lamp subsystem thereof, is individually
selectable by means of an address signal, so that it be possible
to activate the flashing-lamp subsystems at selected stations at
one and/or the other side of the highway, despite the fact that
all the phone stations at both sides of the highway are connected
to a common cable.
FIG. 3 depicts the flash-lamp subsystem and the con-
trol circuitry therefor provided at one such emergency-phone
station NRS: the configuaration of the flash-lamp subsystem and
control circuitry therefor is the same at each of the stations
N~S. The aforementioned first pair of conductors Stl and the
aforementioned second pair of conductors St2 constitute side cir-
cuits which together serve to form a phantom CiLCUit. These two
side circuits are used to transmit code signals to the emergency-
phone stations, i.e., to select the particular stations whose
flashing-lamp subsystems are to be activated for a particular
instance of use, and to select the flash schedule to be followed
at each of the activated stations. Additionally, as described
~ 01~7
1 below, the ene~gy needed to powes some of the ci~cuitry at each
station may be derived from the code signals themselves. The
code signals are abstracted from the side circuits Stl, St2 using
phantom-ciruit couplers Ph2 and are applied to the primary wind-
ing of a transformer U4 provided with three secondary windings
s, z and b. ~he voltage produced across secondary winding s
~s applied to a recti~ier and chargin~ stage GEE ~depicte~ in
detail in FIG. 4), rectified and t~ansmitted in the form of a
code-signal voltage Us to a code-evaluator SE. The code-signal
voltage developed is, as already indicated, of fairly high energy,
and is utilized to charge a current-source condensor Cv. Current-
source condensor Cv serves as a current source for the various
circuit stages which control the flashing action at the station
involved, furni~hing an operating voltage Uv to stages SE, ~G and
BfS. The actions just referred to will be explained in greater
detail with regard to FIG. 4.
As explained in greater detail below, each code signal
comprises an address signal which picks out a station to be acti-
vated and also a schedule signal which determines what flashing
schedule is to be implemented at that station. The schedule
signal is processed by code-evaluator stage SE, and the latter
produces at its output data implementing the flashing schedule
to be followed. Code-evaluator staqe SE includes a conventional
serial-to-parallel converter, which converts the serially arriv-
ing bits of the schedule signal into parallel form at the output
of stage SE; this is indicated in FIG. 3 by the plural-wire out-
put symbol on the output line which leads from stage SE to the
distributor stage Vt of a flash-schedule circuit stage Bfs. The
parallel data at the output of code-evaluator stage SE controls
the operation ~f the distributor stage Vt of flash-schedule cir-
--10--
~Z0117
1 cuit stage Bfs by establishing di~fering combinations of connec-
tions as between terminals 1, 2, 3, 4 and 1', 2', 3', 4' of stage
Bfs. After these terminal connections are once established, they
remain established until disestablished. Aftee the code signals
have been received and the requisite terminal connections have
been established, the actual blinking action commences. During
blinking action, cu~rent-saurce condensor Cv is continua~ly
replenished with charge, so that the circuit stages SE, 8fS and
ZG be continually supplied with operating voltage.
The actual flash energy needed for the flash or blink-
ing action is likewise transmitted along the phantom circuit via
the side circuits Stl and St2. The voltage supplied by the latter
is stepped up across secondary winding b of transformer U4, rec-
tified in the rectifier and charger stage GLE, and aplied in the
form of an appropriate flash voltage ~b to the four flash lamps
BR1-BR4 of the flash-lamp subsystem BE of the emergency-phone
station. The flash voltage Ub is smoothened by a condensor Cb.
A charging diode D prevents backflow of charge from the charged
condensor Cb.
The flash-schedule circuit stage Bfs co~prises a
stepping switch T, which is controlled by a counting stage ZG.
The counting stage ZG counts 50-Hz half-cycles of, for example,
the voltage supplied to the phone station's exterior light or
of the voltage supplied to the kilome~er-indicatos light of t~e
station's mouthpiece. Each time counting stage zG has counted a
predetermined number of supply-voltage half-cycles, it advances
stepping switch T by one step, to make contact with terminals 1',
2', 3', 4' in cyclical sequence. The voltage developed across
the secondary winding z of transformer U4 is used to charge a
firing condensor Cz, and the voltage Uz developed across the
--11--
ll;~Uli7
1 latter constitutes the firing voltage used to fire the flash
lam~s BRl-~R4. Firing voltage Uz is applied to the inp~t termi-
nal of stepping switch T, for successive application to terminals
1', 2', 3', 4'.
Depending upon which of terminals 1, 2, 3, 4 have had
connections established by distributor Vt to which terminals 1',
2', 3', 4', the firing voltage Uz i~ applied in the requisite
sequence to successive ignition transformers U5.1, U5.2, U5.3,
U5.4. Associated with each of these ignition transformers is a
respective one of four glow lamps GLl-4 and a respective one of
the firing electrodes Hl, H2, H3, H4 of the four electronic flash
lamps B~l, BR2, BR3, BR4. For the sake of simple illustration,
only one glow lamp GLl is depicted in FIG. 3, the others being
indicated by their reference numerals, and likewise only flash
lamp BRl is depicted, the others being indicated by their refer-
ence numerals. When the firing voltage Uz is aplied to ignition
transformer U5.1, glow lamp GLl is fired and, in conventional
manner, theough the intermediary of the high-voltage secondary
winding of ignition transformer U5.1 and the firing electrode Hl,
and in cooperation with the flash voltage Ub applied across the
two main electrodes of flash lamp BRl, efEects firing of the
latter. The firing of the other flash lamps is performed in the
same way.
The firing method employed in FIG. 3 is externally
triggered firing. This is in contrast to the usual method em-
ployed in such highway flash-lamp signalling systems (cf., e.g.,
DE-AS 19 33 436 mentioned above), according to which the moment
of ignition is determined exclusively by the instantaneous state
of charge of each flash lamp's storage condensor. The charging
time allotted for the flash condensor Cb and the firing condensor
-12-
o~7
1 Cz is such that, by the time stepping switch T has advanced to
its next step, the flash voltage Ub and the firing voltage Uz
will have again built up to their rated or designed value~.
FIG. 4 depicts the internal configuration of the rec-
tifier and charger stage GLE of FIG. 3, operative for furnishing
the flash voltage Vb, the firing voltaqe ~z, the code-signal
voltage Vs, and operatinq voltage Vv. The A.~. voltage U ab-
stracted from the phantom circuit is directly stepped up to a
level appropriate for flash energization by the secondary wind-
ing b of transformer U4, is rectified by a full-wave rectifier
Gb, and is transmitted as a rectified but still unfiltered flash
~oltage Ub. The usual voltage stabilization, employed in the
prior art mainly to hold constant the flash-repetition frequency
which is to result, is here unnecessary because the firing of
flash lamps is, as already indicated, externally triggered and
not dependent upon the instantaneous state of charge of the ca-
pacitor Cb ~see FIG. 3) responsible for storing flash-lamp flash
energy.
The firing voltage Uz is derived from the voltage
produced by secondary winding z, the latter voltage applied to
ignition capacitor Cz via a charging diode D9.
The operating voltage Uv is derived from the voltage
prod~ced by secondary winding s, the lattee voltage beinq applied
to a full-wave rectifier Gv, and the eectified voltage used to
charge current-source capacitor Cv throuqh the intermediary of
a charging diode Dll and a charging resistor Rll. The operating
voltage Uv can, of course, be a relatively low voltage, with
secondary winding s dimensioned accordingly.
The code-signal voltage ~s is likewise derived from
the voltage produced by secondary winding s and rectified by
-13-
)117
1 rectifier Gv, and is transmitted to code-evaluator stage S~ as
alre~dy stated. In the exemplary embodiment here disclosed, the
code-signal voltage Us is binary, and its constituent "0" and "1"
bits are represented by a relatively lower and by a relatively
higher voltage level, respectively. Because current-source ca-
pacitor Cv will have its charge continually replenished, i.e.,
during transmission of the two-voltage-le~e~ code-signal voltage
too, the voltage across current-source capacitor Cv is stabilized
by means of a zener diode Zll. Charging diode Dll serves to pre-
vent charqe flow from condensor Cv to the evaluating circuitry
in code-evaluator stage SE, where it might otherwise introduce
misinformation. Resistor R11 serves for decoupling
The circuit stages SE, Bfs and ZG operating off oper-
ating voltage Uv will in general be IC stages, their power con-
sumption accordingly being low compared to that of the actual
flash lamps.
FIG. 5 depicts as a function of time a representative
interval of the pulse-modulated 50-Hz A.C. voltage transmitted
by the phantom circuit for the activation of the flash-lamp sub-
system of one phone station. The A.C. voltage cycles are repre-
sented by the hatching within the rectangular pulses. Keying of
the voltage level of the transmitted A.C. voltage is performed
at the central station from which the A.C. voltage is transmitted.
Il denotes a capacitor-charging pulse. The duration of charging
pulse Il is longer than the constituent signal pulses Is of the
next-following code signal KS. Charging pulse Il serves to charge
the current-source condensor Cv, so that operating voltage Uv be
furnished to circuit stages SE, Bfs and ZG, and perhaps other
incidentally present circuit stages.
The code signal KS is constituted by A.C.-voltage
-14-
17
1 pulses and is here binary coded. Although there exist a variety
of techniques for representing the two logic levels of such a
binary code, here the two logic levels are represented by voltage
level alone. In particular, the lower voltage level Ul represents
the binary state "O", and the higher voltage level Uh represents
the binary state "1". Each of these "O" and "1" pulses has a
duration lasting or a succession of A.C. voltage cycles. The
individual pulses are spaced in time by interpulse intervals RZ.
During the interpulse intervals the transmitted A.C. voltage has
zero amplitude. These A.C.-voltage pulses of the differing ampli-
tudes Uh and Ul are, as described with respect to FIG. 3 and 4,
applied to transformer U4, and in those two Figures the trans-
formed and rectified versions of them are denoted in common as
the code-signal voltage Us.
The code signals are followed by an activation pulse
Ia having a boosted amplitude Um and serving, in a manner described
below, to activate the selected phone stations for commencement
of blinking action. The activation pulse Ia is followed by trans-
mission of A.C. voltage of amplitude Uh, which supplies power to
the activated stations during the course of blinking action. The
duration BB of this transmitted interval of simple amplitude-Uh
A.C. voltage may, of course, be on the order of hours, etc.,
depending upon how long a particular traffic hazard, or the like,
continues in existence. Finally, another pu~se Ie of boosted
amplitude Um terminates the blinking action at all activated
stations.
FIG. 6 is a simplified, unipolar representation of
five differing code signals KS configured in accordance with a
merely exemplary code scheme. The five different code signals
shown are all intended for a single one of the succession of
1 emergency-phone stations involved. These five different code
signals can be used to select, for the one station associated
with these five different code signals, any one of a plurality
of predetermined blinking schedules. Each code signal KS con-
sists of an address signal AS and a schedule signal TS. The
address signal AS is different foe each different one of the
phone stations. In FIG. 6, the address signal AS consists of
fi~e bits. The schedule signal TS determines the num~er of f~ash
lamps which are ~o blink and also the sequence in which they are
to blink. In the concrete example here given, the schedule sig-
nal consists of three bits.
The concrete example here given, in which each code
signal KS consists of eight bits, is arbitrarily selected for
explanatory purposes. Clearly, the number of bits which will
actually be re~uired for the address signal AS will depend upon
the total number of emergency-phone stations to be addressed,
and the total number of bits required for the schedule signal
TS will depend upon the number of different blinking schedules
to be made available. In the example depicted in FIG. 6.
25 = 32 emergency-phone stations can be individually addressed,
and 23 = 8 different blinking schedules can be commanded.
After the requisite number of code signals KS have
been transmitted, i.e., their number depending upon the number
of phone stations selected for activation, activation pulse Ia
initiates blinking action. During blinking action, the activated,
i.e., blinking, stations N~S have their code-evaluator stages SE
disconnected from operating voltage Uv, so as not to draw power
unnecessarily, whereas their blinking schedule circuit stages
BFS and their counting stages ZG remain connected to operating
voltage Uv. During blinking action, the unactivated or non-
-16-
llZ~)117
1 selected stations NRS, i.e., the entirely non-blinking stations,
have all their circuit stages disconnected from the power-line
voltage, with the exception of on~ activation stage at each sta-
tion which remains connected to power-line voltage. This will
now be explained with reference to FIG. 7.
FIG. 7 depicts the same circuitry as shown in FIG. 3,
but somewhat more schematically with regard to the stages already
shown in FIG. 3. As shown in FIG. 7, the circuitry at each
emergency-phone station comprises, in addition to what is shown
in FIG. 3, an activation stage AE, and certain other components
about to be described.
Except for activation stage AE, all circuitry, i.e.,
all circuitry relating to flashing-light signalling, is connected
to the side circuits Stl, St2 of the phantom CiLCUit via relay
contacts al, bl and a2, b2. Relay contacts al, a2 are NO (nor-
mally open) contacts controlled by a relay winding A in activa-
tion stage AE; relay contacts bl, b2 are NC (normally closed)
contacts controlled by a relay winding B. As shown in Fig. 7,
the primary winding of transformer U4 is center-tapped with its
center tap connected to ground.
The activation stage AE comprises a threshold-voltage
switching stage comprised of two zener diodes Zl, æ2, operative
for responding to the boosted voltage amplitude Vm referred to
earlier, and therefore responsive to the activation pulse Ia and
the termination pulse Ie. The breakdown voltage Ud of the zener
diodes Zl, Z2 is greater than the voltage amplitude Uh of the
charging pulse Il and of the A.C. supply voltage, likewise of
amplitude Uh, transmitted during the interval BB for the powering
of blinking action. So long as the zener diodes Zl, Z2 remain
ir. non-conductive state, negligible current flows through them.
)117
1 Ins~ead of zene~ diodes, use could be made of thy~is~ors, schmitt
triggers, or the like.
After the charging pulse Il, which assures that ade-
quate operating voltage Vv will be available, the code-signal
voltage Us is applied to the code-evaluator stages SE of all
phone stations in common. If, for example, three stations are
to be activated for flashing action, the code-signal voltage Us
will comprise three successive code signals KS, each one pertain-
ing to one of the three selected stations. When the station whose
circuit is assumed illustrated in FIG. 7 receives the code signal
KS pertaining to it, it responds to the address-signal component
AS thereof by transmitting the operating voltage Uv via a control
line Sl (this control line not shown in FIG. 3) and via a relay
contact a3 to relay winding A. Winding ~ is now energized, its
current path being completed by a further relay contact a4. With
winding A now energized, its associated relay contacts al, a2, a3,
a4, switch over from their illustrated to their non-illustrated
settings. ~s relay contacts a3, a4 change setting, and therefore
briefly interrupt the current path of winding A, a capacitor Ca
maintains winding A energized until the relay A, al-a4 has com-
pleted its change of state. No contacts al, a2 now close, shunt-
ing NC contacts bl, b2. It is emphasized that this happens only
at the phone stations which have been selected for flashing.
Later, ~C contacts bl, b2 will open at all stations, both those
selected for flashing action and those `not selected. Accordingly,
if the station involved is one which has been selected for flash-
ing, the closure of contacts al, a2 assures that the transformer
U4 at that station will remain connected to the phantom circuit.
With relay contacts a3, a4 now in their non-illus-
trated settings, the lower terminal of winding A is disconnected
-18-
11;~0117
1 from the grounde~ terminal of current-source capacit~r Cv, and
the upper teeminal of winding A is disconnected from the operat-
in~ voltage Uv which the code-evaluator stage SE has applied to
control line Sl, i.e~, which has been applied to line Sl if the
station involved has been selected ~or flashin~ action. Acc~rd-
ingly, relay winding A is now disconnected from the current-
source capacitor Cv of the rectifier and charger stage GLE.
The two relays A and B are magnetic, bistable latch=
ing relays. Accordingly, ~he contacts al, a2, a3, a4 of relay A
remain in their non-illustrated setting, despite the disconnec=
tion of winding A from operating voltage capacitor Cv. Specifi=
cally, contacts al-a4 remain in their non-illustrated settings,
until there is applied to relay winding A a pulse having a polar-
ity opposite to that of the voltage which caused this relay to
convert to its non-illustrated state. If relay A, when in non-
illustrated state, receives further pulses of the same polarity
as the voltage which effected the transition to non-illustrated
state, the relay merely remains in its non-illustrated state.
As already explained with regard to FIG. 3, the con-
trol lines 2 emanating from code-evaluator stage SE cause flash
schedule circuit stage Bfs to establish the commanded flash or
blinking schedule. The flash schedule circuit Bfs registers the
flash-schedule command, and requires operating voltage Uv to con-
tinue this registration durinq flashing action. Accordingly,
in the case of a station selected for flashing, flash schedule
circuit Bfs must remain connected to operating voltage Uv.
Flash schedule circuit Bfs is kept connected to oper-
ating voltage Uv as follows. The positive terminal of current-
source capacitor Cv, denoted Uv, is connected to the positive
3~ operating-voltage supply terminal of stage Bfs permanently, as
17
1 shown in FIG. 7. A ~round terminal within stage Bfs, denoted ~,
is connected to the grounded terminal of current-source capacitor
Cv through two diodes D2~ D3 and a relay contact b3 associated
with relay wind~ng ~. ~ccordingly, no matter which of its two
settings ~elay contact b3 ass~mes, the gro~nd terminal 0 within
stage B~s remains connected to the grounded terminal of capacitor
Cv, and accordingly the output voltage of capacitor Cv remains
connected across the operating-voltage input of stage Bfs.
Operating voltage Uv is applied across the operating-
voltage inputs of code-evaluator stage SE and o~ counting stage
Z~ in a similar manner. I.e., the positive terminal of cur~ent-
source capacitor is permanently connected to the positive terminal
of the operating-voltage input of each of stages SE and ~G, and
the ground terminal 0 of each of these two stages SE and ZG is
connected to the grounded terminal of capacitor C`v through the
intermediary of relay contact b3. HoweveL, whereas operating
voltage Uv remains applied across stage Bfs no matter what the
setting of contact b3, the situation is different for code-
evaluator stage SE and counting stage ZG. In particular, the
operating-voltage input of stage SE is connected across current-
source capacitor Cv only when contact b3 is in its illustrated
setting. Conversely, the operating-voltage input of stage ZG
is connected across capacitor Cv only when contact b3 is in its
non-illustrated setting.
After all the code signals KS of the code-signal
voltage Us have been transmitted, the flash schedule circuits
~fs at all selected stations will have registered their respec-
tive flash-schedule commands, and the relay contacts al-a4 at
each selected station will be in non-illustrated setting. The
relay contacts al-a4 at each non-selected station will be in
-20-
l~ZOli7
1 illustrated setting.
The code si~nals KS are, as shown in FIG. 5, followed
by the activation pulse Ia, which is of elevated amplitude Um in
excess of the breakdown voltage Ud of zeneL diodes Zl, z2. Until
now, relay winding B has not yet been energized, and its associ-
ated contacts bl-b4 are as yet still in their illustrated settings.
~ecause contact b4 is in its illustrated setting at the time of
arrival of the activation pulse Ia, pulse Ia is applied via a
relay contact n to a diode D4, which ~atter transmits only the
positive half-cycles of the Um-amplitude pulse Ia. The positive
half-cycles effect breakdown of zener diode Zl, and the latter
transmits positive current through a relay winding P and through
relay winding B, for the duration of activation pulse Ia. First
in time, this positive current activates relay P and thereby
causes associated relay contact p to switch over from its illus-
trated to its non-illustrated setting. Second in time, due to
the provision of a capacitor C across winding B, this positive
current activates the bistable magnetic latching relay B, causing
contacts bl-b4 to change over to their non-illustrated settings.
Because contacts a3, a4 are at this time in their non-illustrated
settings, this positive current furthermore is applied to the
winding of relay A, but without effect because relay A has already
changed state in response to a positive current and can now only
change state in response to a negative current.
Because, in response to activation pulse Ia, contact
p changes to non-illustrated setting before contact b4 does, pulse
Ia will continue to be applied to diode D4 after contact b4 has
indeed changed to non-illustrated setting. Accordingly, the
flow of positive current transmitted by zener diode Zl will con-
tinue until the end of activation pulse Ia. ~uring the brief
-21-
ll'ZUli7
1 interruption in the positive current teansmitted b~ diode Zl,
i.e., as contact b4 switches over to non-illustrated setting,
winding B will be kept energized by the capacitor C connected
across it. To keep winding P energized during this brief inter-
ruption, it is not necessary to similarly pro~ide it with a shunt
capacitor, i~ the drop-out action of relay P is sufficiently s~ow,
simi~ar remarks apply to ~1ay ~, not yet discussed. However,
if a shunt capa~itor were in fact ~rovided across e~lay winding
P ~and analogously across relay winding N), the time-constant
introduced by such shunt capacitor could readily be selected
such that, as already stated, contact p change over to its non-
illustrated setting before contact b4 does.
In any event, in response to the activation pulse
Ia, relay B does undergo a change of state, and its associated
contacts bl-b4 change to their non-illustrated settings. This
happens both at stations which have been selected for flashing
action and at stations which have not been selected. At the non-
selected stations, contacts bl, b2 are now open, as are also con-
tacts al, a2, and thus the transformers U4 at the non-selected
stations are disconnected from the phantom circuit~ At the
selected stations, contacts bl, b2 are likewise open, but contacts
al, a2 have earlier been closed, so that the transformers U4 at
the selected stations remain connected to the phantom circuit.
Accordingly, at the non-selected stations, all cir-
cuitry shown in FIG. 7 is disconnected ~rom the phantom circuit
and thereby disconnected from power, except for the activation
stages AE at the non-selected stations.
After the activation pulse Ia has been transmitted,
the contacts b3 at all stations, both selected and non-selected,
are in non-illustrated setting. Accordingly, at the selected
-22-
1 stations, the code-evaluator stages ~E are disconnected from
operating volta~e Uv, whereas t~e ~lash s~hedulè staqes ~fs and
the counting stages ZG are connected to operating voltage ~v.
Similar connections exist at the non-selected stations, but at
the non-selected stations the transformers U4 are disconnected
from the powering phantom circuit.
The contacts b3 at all selected stations (and indeed
at the non-selected stations as well) all change o~er to non-
illustrated setting simultaneously, applying operating voltage to
all the counting stages ZG of the selected ~tations simultaneously.
In order to assure that all counting stages ZG start at the same
initial count, use can be made of counting stages of the type
which automatically reset when operating voltage is first applied
to their operating-voltage input. This serves to establish a pre-
determined phase interrelationship as among the flash schedules
which will be followed at the individual ones of the selected
stations.
During the interval BB of actual blinking operation
(see FIG. 5), A.C. voltage of amplitude Uh is trans~itted alonq
the phantom circuit. This amplitude is lower than the breakdown
voltage Ud of zener diodes Zl, Z~. The amount of c~rrent which
these diodes draw during the long interval BB of blinking action
is negligible.
When the blinking-action interval BB commenced, i.e.,
upon termination of the activation pulse Ia, relay P became un-
energized. Accordingly, during the course of blinking action,
contact p is, asain, in its illustrated setting.
When blinking action is to be terminated, e.g.,
because the traffic hazard being signalled is no longer present,
a termination pulse Ie tsee FIG. 5) is transmitted. This ter-
-23-
11'~()117
1 mination ~ulse le, like activation pu~se ~a, has an ampl itude Urn
~reater th~ t~ bl~nkin~-interval A.C. ~oltage amplitude ~h and
greater than the ~reakdown voltage Vd oF the zener diodes.
When termination pulse Ie is transmitted, it is
applied via contact b4 ~w~ich is in its non-illustrated setting)
and via contact p to diode D~, the latter transmitting only the
ne~ative half-cyles thereof. The amplitude of the negative half-
cycles exceeds the breakdown voltage of zener diode Z2, and the
latter transmits negative current through relay winding N, through
relay winding B, and through relay winding A. Bistable relays A
and B return to their original states, so that upon conclusion
of the termination pulse Ie, all relay contacts al all stations
will again be in the settings illustrated in FIG. 7, i.e., in
preparation for a new selection of phone stations for flashing
action. The relay winding N and its associated contact n serve
a purpose analogous to that of winding P and contact p.
In the illustrated embodiment, initiation and ter-
mination of actual blinking action are effected in response to
pulses of boosted amplitude Um, but the relay windings which are
energized as a result are energized by current derived from a
voltage which is approximately equal to the diEference between
Um and the zener-diode breakdown voltage Ud. Therefore, despite
the high absolute values of the voltages involved, the voltage
difference in question is, by comparison, small and suitable for
direct application to the relays A, B, N and P, i.e., without
the use of protective, voltage-reducing measures invol~ing volt-
age dividers, series current-limiting resistors, or the like.
Because the successive phone stations are located at
differing distances from the central station from which they
receive power, the voltage drops at the power-supply line used
-24-
11;~0117
1 will he di~cnt at di~ferent stations. ~n ord~r to ass~e
that sufficient voltage is p~ovided at eac~ station for ener~iza-
tion of the relays A, B, N and P, Um may be selected high enough
to assure reliable energization of these relays at the most dis-
tant of the succession of phone stations. The energizing current
supplied to these relays at the station closest to the central
station will then be higher than at the most distant station. In
general, however, this will not be problematic, because the dura-
tion of the boost to amplitude level Um wil anyway be very short;
furthermore, the mount of the amplitude boost (Um - Uh) need only
be such that the energizing current for the relays of the most
distant station will just exceed the minimum energizing current
needed for relay operation. Similar considerations apply to the
fact that the relay-activating current which each individual sta-
tion draws will depend upon whether it is a selected or a non-
selected station; in the case of a selected station both relay A
and relay B are energized, whereas in the case of a non-selected
station only relay B. However, if actually considered necessary,
current limiting resistors could be provided in the activation
stages SE of the closer stations, i.e., such as to reduce the
relay-energizing currents which develop down to the level of
those which develop at the most distant station.
It will be understood that each of the elements de-
scribed above, or two or more together, ma~ also find a useful
a~plication in other types of circuits and constructions, differ-
ing from the types described above.
While the invention has been illustrated and de-
scribed as embodied in a highway signalling system which makes
use of a succession of emergency-phone stations in particular,
it is not intended to be limited to the details shown, since
-25-
~l~V117
~,rarious modi~icati~ns and structural changes may be made with~ut
depaLtin~ i.n any way from the spirit o~ the present invention,
