US3114127A - Traffic light controller - Google Patents

Description

Dec. 10, 1963 J. E. RAMSEY 3,

TRAFFIC LIGHT CONTROLLER Filed March 5, 1962 3 Sheets-Sheet l OSCILLATOR OSCILLATOR OSCILLATOR L 300cy 400cy 500cy M8 T9 Antx i TRANSMITTER Fig.l

I INVEN TOR. JAMES E. RAMSEY WWW Dec. 10, 1963 J. E. RAMSEY 3,114,127

TRAFFIC LIGHT CONTROLLER Filed March 5, 1962 3 Sheets-Sheet 2 RADIO RECEIVER ACTUATOR MODULATION SENSITIVE MANUAL FLASH MAGN'ET INVENTOR. Fig. 2 JAMES E. RAMSEY Dec. 10, 1963 J. E. RAMSEY TRAFFIC LIGHT CONTROLLER Filed March 5, 1962 3 Sheets-Sheet 3 2o RADIO RECEIVER 7 ZO L/ 2| MODULATION-SENSITIVE [1 ACTUATOR Hi -E U J7 48 INVENTOR. Fig 3 JAMES E. RAMSEY BYWW AWORNEYS United States Patent 3,114,127 TRAFFIC LIGHT CONTROLLER James E. Ramsey, New Castle, Pa., assignor, by mesne assignments, to Electronic Traiiie Control Inc., New Castle, Pa., a corporation of Pennsylvania Filed Mar. 5, 1962, Ser. No. 177,413 14 Claims. (Cl. 340-32) This invention relates to emergency traflic-light controller systems, and more particularly relates to novel improvements in remotely-controlled traflic-light systems whereby an emergency vehicle such as an ambulance or a police car can by remote means located within the vehicle control traffic lights which it is approaching so as to present a go signal along the path of the vehicle and red lights to vehicles approaching on crossing streets.

It is a principal object of this invention to provide radio control means for controlling traflic lights in which a transmitter of limited range is located within the emergency vehicle, or alternatively in a tratfic-control helicopter, and in which receivers are located at each trafiiclight-controlled intersection, the receivers being tuned to the transmitter carrier frequency.

It is another very important object of the present invention to provide a radio frequency control system em ploying control signals which are coded with at least two different modulating frequencies which must both be present at the receiver in order to switch over the traffic light controller from local to remote, whereby accidental interference with the normal function of the traflic-controller which might be caused by spurious signals is vir tually precluded.

The present system includes the remotely-located transmitter in the vehicle and equipped with two or more push buttons having identifying markers thereon. In order to assist the driver of the vehicle to determine which button should be pushed as a light-controlled intersection is approached, the identifying markers on the buttons are also posted on placards or discs attached to the utility poles approaching the intersection, each of these placards displaying the identifying marker corre sponding with the marker on the push button that should be pressed by the operator in order to have the right-ofway when the vehicle enters the intersection. More than two push buttons may advantageously be provided in the vehicle for the purpose of controlling the lights at a more complicated intersection having, for example, a left-turn light or having perhaps a non-rectangular intersection requiring a selection as between two possible exit direc* tions. These special situations could generally be covered by a third button, or perhaps several additional-buttons in the vehicle having markers corresponding with the more specialized alternative-light patterns. At any rate, each of the push buttons is coupled with a modulation signal generator having a unique frequency or other characteristic, the present invention being illustrated in connection with audio frequency modulation oscillators which are tuning-fork stabilized.

As stated above, in order to avoid unwanted actuation of the traffic-light controller by spurious signals two different modulations are used in the transmission of each complete control signal, one of which modulations is a coding signal which is common to all of the buttons which can be pressed in the vehicle and serves to enable the controller for remote control, and the other of which signals is unique to the particular button depressed in the vehicle and identifies a preferred direction of travel of the vehicle. In addition, the push buttons are provided with slow return means, such as dashpot means, so that once the button is depressed, it returns from the down position over an interval comprising a certain number of seconds designed to assure that the message from the vehicle will be of sufficient duration to actuate the trafficlight controller. The push buttons, their modulating os cillators, and the additional modulation oscillator which is common to all of the push buttons are all connected to modulate the output of a low-powered transmitter.

This low-powered transmitter is picked up at each controlled intersection by a small radio receiver having an omnidirectional antenna and connected to the trafiic-light controller. The radio receiver is connected with a tuned modulation-sensitive relay means which, when supplied with the modulation frequency which is common to all of the push buttons plus one of the other modulation frequencies unique to one of the push buttons, actuate sets of switching contacts which cause the standard trafliclight controller itself to interrupt its normal automatic function to provide the type of light-control selected by the approaching vehicle, as evidenced by the particular unique modulation present in the received control signal. This signal continues to affect the traflic-light controller for a predetermined interval as determined by a timer in the tuned relay system, and at the end of this interval the relays are released and the automatic function of the controller resumes.

Another object of the invention is to provide a remotecontrol system which can be connected to a standard trafiic-light controller, such as the EA70 Series Controller manufactured by the Eagle Signal Corporation, and which system when so connected can take over control therefrom for emergency purposes, and subsequently return control to the controller unit in such a way that the latter can then synchronize itself with other traflic lights at other intersections so that the temporary disruption does not throw the controller out of synchronism with the other controlled intersections once the emergency has passed.

Other objects and advantages of the invention, and a working embodiment thereof, will become apparent dur-' ing the following discussion of the drawings, wherein:

FIG. 1 is a schematic diagram illustrating a transmitter according to the present invention to be located in an emergency vehicle;

FIG. 2 is a schematic diagram illustrating the stationary equipment to be located at the trafiic-light controller, and showing one such controller, the diagram of which has been somewhat simplified to omit details which are unimportant to the present disclosure; and

FIG. 3 is a schematic diagram illustrating in greater detail the modulation-sensitive actuator relay means shown in block diagram form in FIG. 2.

Referring now to the drawings, and in particular to FIG. 1, which illustrates the special transmitting equipment to be located in the emergency vehicle, this equipment includes an antenna Ant located conveniently on the vehicle (not shown) and connected with a transmitter 1 which in turn is provided with coded modulation frequencies as hereinafter discussed. The equipment also includes, in the present illustrative example, three push buttons 2, 3 and 4 which are respectively supported by and controlled by three dash-pot means 2a, 3a and 4a, these dash-pot means being of any conventional design and slowly releasing the push buttons upwardly once they have been depressed by the driver of the vehicle. Each of the push buttons includes a shaft, respectively labeled 2b, 3b and 4b, and each shaft having a projection respectively labeled 2c, 30 and 40 to actuate the spaced arms on an adjacent two-circuit switch. For instance, the projection 2c actuates the arms on a switch 6, but only during rising of the shaft 2b in the direction of the arrow located thereon. In other words, when the push button 2 is depressed the projection 2c moves downwardly toward the dash-pot 2a and then as the button is released, the projection 2c rises upwardly first raising the arm 6a so as to close the lower circuit of the switch 6 and then at a somewhat later instant raising the arm 61) so as to close the upper circuit of the switch. The switches 7 and 8 are operated in an identical manner respectively by the projections 3c and 4c. All three of the lower circuits of the switches 6, 7 and 8 are connected to a wire 9 which wire serves to energize the ZOO-cycle tuning fork oscillator it) when the wire 9 is grounded.

The schematic diagram of the oscillator 19 is illustrated in FIG. 1 and includes a tuning fork Fa connected between two windings 10b and 190 which are provided with bias by a resistive voltage divider and which windings control a transistor lttd which furnishes the gain necessary to sustain oscillations. This type of oscillator is well known and will not be discussed in any greater detail because of the fact that the oscillator is available as a commercial component from Stephens-Arnold, Inc, South Boston, Mass. Incidentally, the potentiometer adjustment 10a serves to adjust the oscillation for maximum amplitude. Three other similar oscillators 11, 12 and 13 are illustrated.

The oscillator 11 is tuned to a different selected frequency, for instance 300 cycles in the present illustration, and this oscillator is connected by a wire 15 to the upper switch contacts 612 for control by the switch 6. Thus, as the shaft 2b returns upwardly at the push button 2, the oscillator 10 is first energized and the oscillator 11 is energized thereafter, and these two modulations are sequentially transmitted by the transmitter 1 to the receiving equipment at the controller, to be described hereinafter. In a similar manner, the oscillator 12, for example 400 cycles, is connected by a Wire 16 to the upper circuit of the push button 3, and the oscillator 13 is connected by a wire 17 to the upper circuit of the switch 8. If the push button 3 is actuated, the ZOO-cycle oscillator is first energized, and subsequently the 400-cycle oscillator 12 is energized; but on the other hand if the push button 4 is depressed, the 2G0-cycle oscillator It is first energized, followed by energization of the SOD-cycle oscillator 13 as the projection 4c on the push button 4 travels upwardly past the switch 8. The outputs of oscillators 1t), 11, 12 and 13 are all connected to the wires 18 and 18 which lead into the transmitter 1 so as to modulate the transmitter in accordance with whichever of the push buttons is depressed.

The oscillators 1t), 11, 12 and 13 are connected with a source of supply voltage represented by the plus sign at the wire leading from each oscillator, this wire being suitably connected to a battery, such as the battery of the emergency vehicle.

Turning now to the description of the contents of FIGS. 2 and 3, which are best described simultaneously, these figures illustrate the stationary units located at the tratficlight controller in each intersection. These units comprise a conventional radio frequency receiver 26 coupled with a small receiving antenna Ant located near the inplaying three different colors in each direction. On the main highway, there are three lights: green, amber and red, and labeled 1G, 1A and IR in FIG. 2. On the secondary highway crossing the main highway there are also three lights: green, amber and red, which lights are labeled 26, 2A and 2R, and all of these lights are connected with one side of a source of power schematically represented by the plug P at the bottom of FIG. 2.

The other ends of each of these lights is connected with an arm of a different cam-operated switch each including a cam carried on a common cam shaft S intermittently rotated by a ratchet stepping motor M operating, through suitable mechanical linkage, a ratchet wheel W advanced tersection, the receiver 20 being connected with modulation-sensitive actuators 21 which receive the radio-frequency signals picked up by the receiver, and which contain tuned frequency-sensitive relays which convert the coded modulation from the transmitted signal of the vehicle into positions of switch contacts which are connected into the conventional traffic-signal controller K in order to take over control thereof upon receipt of a remote-control signal.

by a pawl shown adjacent to the wheel. The ratchet motor is of a weight-operated type such that when the winding of the motor is energized, a weight (not shown) attached to the pawl is raised, and when the circuit is roken to the ratchet motor winding, the weight falls and advances the shaft one ratchet position, which amounts to a predetermined number of degrees on the standard controller. In addition, a synchronous timing motor N having a conventional switching dial runs all of the time and is controlled by a switch N by which the motor can be shut off during servicing of the equipment. Otherwise, the switch N' is normally closed so that the synchronous motor runs all of the time. This motor has a plurality of contacts on its switching dial which are closed and opened in sequence by the motor N. There is an impulse contact I controlled by the synchronous motor, and there is a release contact R which is also sequentially controlled by the synchronous timing motor N. Finally, there is a set of flasher contacts P which are continuously closed and opened at a relatively higher rate of speed so that when these contacts are placed in circuit by other switching means as subsequently described, the lights can be made to perform a flashing function, as is familiar to experienced motorists.

There is also an automatic-manual switch C located in the traffiolight controller K and arranged in such a manner that when connected to automatic, the syn-.

chronous motor N timing system automatically advances the stepping motor M to rotate the shaft S and operate the lights in a predetermined sequence, and when the switch C is connected to the manual position, the automatic feature is disconnected and the stepping ratchet is advanced only by the manual control switch X, this switch energizing the ratchet motor winding M each time the switch is depressed and thereby raising the weight on the pawl as mentioned previously, but releasing the weight to fall and advance the shaft S one position whenever the manual push button X is released. An insulating strip B shown just above the cam shaft S supports a plurality of contacts all connected in parallel and connected to the power line P through the signal shutdown switch Y which is normally closed. This plurality of contacts supported on the insulator strip B corresponds in each case with a contact arm such as the arm A, which arm is actuated by a lobe L on the associated cam as the shaft S rotates. This structure is conventional and very well known in connection with signal controllers and needs no further explanation. At the right end of the insulating strip B and the cam shaft S are illustrated several other cams and switch arms shown in dotted lines to illustrate the manner in which further circuits are added to the cam shaft in order to control more complicated intersections having left-turn lights and other similar additional functions.

As the cam shaft rotates the circuits are sequentially completed through the arms A and through the appropriate lights, such as the light 1R, and then to the other side of the power line P". One additional cam is shown on the shaft S as associated with a contact arm A connected in series with the impulse contact switch I which is continuously rotated by the synchronous timing motor N. This contact serves to re-synchronize the cam shaft S with the synchronous motor N position. This is another well-known feature of traflic controllers by which, once for each revolution of the cam shaft S, the arm A opens and remains open until the synchronous timing motor catches up with the position of the shaft S. In this way, the shaft, if out of step with the motor N, is caused to pause until the synchronous motor N reaches a certain position, and then the shaft proceeds again in step with the synchronous timing motor. This conventional feature is of importance because of the fact that the traflic-light controller synchronous motor N is synchronized with the motors of the other controllers for diiferent intersections and this motor is never interrupted or stopped. On the other hand, the position of shaft S is sometimes separated from control by the synchronous timing motor N as when being controlled by the modulation-sensitive actuator 21. When the control by this actuator has ceased, however, it is then necessary for the ratchet motor M to be controlled once again by the synchronous timing motor N, and it is the delay caused by the cam and the wiper arm at A which permits the ratchet motor to wait until the synchronous motor reaches a certain position before falling into step therewith. At the left end of the shaft S there are three additional auxiliary cams serving the purpose to be hereinafter described in connection with the description of the modulation-sensitive actuator 21 shown in detail in FIG. 3. In further describing the portion of the traflic signal controller K illustrated in FIG. 2, this system also includes flasher means controlled by the switch Z such that when this switch is closed current is passed through the flash magnet Q having contacts Q1, Q2 and Q3, all of which are normally open. This magnet is supplied with current from the line P" on one side and from the line P through the switch Z on the other side, and the energizing of the flash magnet Q also causes opening of the contacts Q4 which are normally closed. This breaks the circuit of the automatic control through the switch C so that the ratchet motor is no longer caused to rotate in step with the synchronous timing motor. However, as stated above, this synchronous motor continuously makes and breaks the set of contacts marked F and thereby connects current from the power line P through the switch Y and the flasher F and through the contacts Q3 and Q2 into whichever of the electric-light bulbs is connected with the contacts Q2. For instance, the red light of the secondary highway labeled 2R is shown connected with the contacts Q2 so that this light will flash red continuously as the intermittent flasher circuit through the contacts F is made and broken by rotation of the synchronous motor N.

Turning now to a description of the structure and manner of operation of the modulation-sensitive actuator, it will be seen that in both FIGS. 2 and 3 a bank of coupling jacks is provided between the actuator 21 and the controller K, these jacks comprising connections marked J1, J2, J3, J4, J5, J6, J7 and IS, the same contacts being duplicated in both FIGS. 2 and 3. The jacks J4 and J8 carry power respectively from the signal controller K to the modulation-sensitive actuator 21, respectively from the two sides of the power line P" and P. These power lines connect with an ordinary bridge rectifier 22 which delivers to the lines 23 and 24 positive and negative DC. voltage filtered by a capacitor 25 in a manner known per se. This DC. voltage is used to energize the relays which are present in the modulationsentitive actuator 21 and which will be hereinafter described. There are four of these relays each having a DC. winding, these windings being labeled 30, 31, 32 and 33. All of these windings have their left ends connected with the D.C. power line 24. Across each of these windings is an RC delay circuit comprising a series capacitor and resistor, these circuits being labeled 30d, 31d, 32d and 33d, and these RC circuits serving in a manner well known per se to delay opening of the relay for a short interval of time after the circuit thereto is broken.

The right sides of each of the windings 31, 32 and 33 are respectively connected through switch contacts which control whether or not current is passed from the other side of the power line 23 to these four windings, which incidentally can not all be energized at once as will presently appear.

Among the contacts which are connected in series with the windings of the relays 31, 32 and 33 are the contacts of four tuned frequency-sensitive relays, including the relay 40 tuned to 200 cycles, the relay 41 tuned to 300 cycles, the relay 42 tuned to 400 cycles, and the relay 43 tuned to 500 cycles, these relays each having an energizing winding which is coupled to the modulation output signal of the radio receiver 20 by the wires 20a and 2012. Thus, whatever modulation tones may be present on the wires 20a and 20b from the receiver 20 will energize the resonant windings associated with the relays 40, 41, 42 and 43, and where the modulation tone on the wires 2tta-20b corresponds with the tuning of the winding of the resonant relay, that relay switch 46, 41, 42 or 43 will be closed.

For example, suppose that the first push buutton 2 shown in FIG. 1 is depressed, meaning that the transmitter first transmits a ZOO-cycle tone and then subsequently transmits a 300-cycle tone. When the ZOO-cycle tone is received by the receiver 20, it appears on the wires 20a and 20b but it can actuate only the relay 40 which is resonant at that frequency. The relay contacts 40 therefore close and deliver power from the power line 23 through the contacts 40, into the coil 30 which causes this relay to close thereby closing the contacts 30a, 30b and 300. The relay 30 remains energized, and this energization closes all of the contacts 30a, 30b, 30c and 30h, the latter contacts comprising a hold circuit continuously maintaining power through the relay winding 30 to hold it closed. Also, a timer 35 is included in series with the contacts 30h and is turned on thereby, and this timer runs for a predetermined interval, for instance 15 seconds, and then opens its normally-closed contact 35a. When these contacts open, the hold circuit through the contacts 30h is broken and the relay coil 30a is then permitted to open for the purpose to be hereinafter described. The time of operation of the timer 35, before it releases the winding 30 by opening its normally-closed contact 35a, is adjusted to permit the emergency vehicle time to pass through the intersection and be gone.

As a result of the closing of the switch 30, the controller K is placed in an enabled condition so that if the vehicle transmitter 1 transmits a 300, a 400, or a 500 cycle signal, the controller will react thereto, but in every case actuation occurs only if the receiver has received the ZOO-cycle coding or enabling signal plus one of the other signals at 300, 400 or 500 cycles per second. This enabling condition is established when the relay 30 has been actuated to close the contacts 30a, 30b, and 30c and its own holding contacts 30h. The closing of the contacts 30a energizes the DC. power line 23a by connecting it to the output of the rectifier 22 on the positive side thereof, and when this line is energized, current can be passed from they rectifier through one of the other windings 31,32 or 33 if a tone appears on the output lines 20a and 20b from the receiver which tone corresponds with the resonant frequency of one of the relays 41, 42 or 43. Assume, for example, that the transmitter 1n the vehicle has just put out a SOD-cycle modulation, which modulation closes the switch 41 and energizes the winding 31. When this occurs, the normally-open hold contacts 31h are energized, which contactsv maintain the line 31 energized through normally-closed contacts 32a and 33a of the other relays shown in series with the line, which contacts will be presently described.

On the other hand, if a 400-cycle tone should appear at the output of the receiver, the resonant relay 42 would then close and would thereby have energized the winding 32 to close the hold contact 32h. Likewise, a 500- cycle tone would have energized the resonant relay 43 to energize the winding of the relay 33 and close the hold contacts 33h in order to retain this energization. The resonant relays 40, 41, 42 and 43 have not been described in greater detail in this specification because of the fact that they are also manufactured items commercially available from Stephens-Arnold, Inc.

The relays 3t), 31, 32 and 33 have other contacts besides their hold contacts. For example, the relay 31 has contacts 31a, 31b and 310 all of which are normally closed, and also includes a normally-open contact 311:. Similarly, the relay 32 has normally-closed contacts 32a, 32b and 320, and normally-open contact 32c. The relay 33 has normally-closed contacts 33a, 33b and 330, and normally-open contacts 33e. By inspection it will be seen that when the relay 31 is actuated it can close only if normally-closed contacts 32a and 33a in series with its winding are closed. Thus if the relay 32 is actuated, it becomes impossible to actuate relays 31 or 33 because the normally-closed contacts 32:: and 32b are open. Similarly, when the relay 33 is actuated, relays 31 and 32 can not be energized because the normally-closed contacts 33a and 33b are opened and in series with the respective other relay windings. Thus, these normally-closed contacts prevent actuation of more than one of the relays 31, 32 or 33 at a time. Moreover, when one of the relays, such as the relay 31, is actuated, the normally-open contact 31e becomes closed and connects power from the power line P to the leftmost auxiliary cam 45, and the connector J1 and this cam switch depending on the position of the shaft S will actuate the flash magnet Q and cause flashing of whatever lights are connected to the flasher F via contacts such as contacts Q2 and Q3. On the other hand, if the relay 32, FIG. 3, is energized, the normally-open contact 32c will be closed, and will energize a circuit past the cam switch 46, assuming that the cam is in a position to close the contact associated therewith. If it is in such position, again the flash magnet Q will be energized and will flash whatever light happens to be connected by the light-controlling cams on the cam shaft at the time. A similar circuit also works in connection with the relay 33, whereby if this relay is energized, the contacts 33c are closed to energize a circuit by way of the cam 47 and the contacts associated therewith, and again energize the flash magnet Q. However, note that none of the switch contacts Sle, 322 or 33c can affect the trafiic controller cam system unless the relay 30 is closed so as to close the normally-open contacts 30b, here again requiring that the coding relay 30 be closed in order to place the system in an enabled condition.

Finally, when the circuit is enabled, meaning that the relay 30 is energized and that it has closed its contact 30c in FIG. 3, a circuit is completed from the power line P in FIG. 2 through the switch Y and the flasher F, through the contacts Q3 and Q1 and through the jack J6, in FIG. 3, to the then-closed contacts 300, and from there through the contacts J5 to the ratchet stepping motor M. Also, power is additionally supplied from the jack J6 through the then-closed contacts 30c and to the jack J7 which is connected in series with the automanual switch C. As soon as one of the relays 31, 32 or 33 is closed by a subsequent tone operating one of the relays 41, 42 or 43, one of the normally-closed relay contacts 31c, 320 or 33c becomes opened and breaks the connection of power from the auto-manual switch, which would normally actuate the ratchet motor M through the jack J5. Thus, it will be seen that the traflic-light controller K is thereby disconnected both as to manual and automatic operation, and then is fully controlled by the modulation-sensitive actuator 21.

However, when the modulation-sensitive actuator 21 has taken over control of the traffic controller K, thereby disconnecting the ratchet motor M from the auto-manual switch C, the current which is supplied to the ratchet motor is intermittent since it comes through the intermittent flasher K through the contact Q1 before it arrives at the jack J6. Therefore, since the power to the ratchet motor is furnished intermittently because of the action of the flasher R, the ratchet motor is caused to step rapidly around, performing one step each time the flash contacts F open. In the meantime, current is being supplied through one of the auxiliary switch contacts 45, 46 or 47 to the hash magnet Q, that is, until this current is broken by opening of that cam switch. For instance, if a 3GO-cycle tone has been received and has closed the relay 31, then power will be supplied to the flash magnet Q through the contact 31e and through the auxiliary cam 45, and will cause operation of the flash magnet Q, but only until the cam shaft S has stepped around sufliciently to open the contacts connected with the cam 45. When this occurs, the flash magnet Q is no longer energized, current is broken through the contacts Q1, Q2 and Q3, and therefore the ratchet motor ceases to step the shaft 5 around, and whichever ones of the lights 1G, 1A, IR, 26, 2A or 2R are connected to power in that particular position of the cam shaft S remain lighted. In this particular instance, as illustrated, the tratfic light 1R would be red since its cam switch is closed and the lights 1G and 1A would remain off, since their contacts are open. On the other hand, the traflic light 26 is energized since its cam switch is closed, and contacts 2A and 2R remain open. Therefore, the main highway light is red, and the cross-street light is green according to this particular set of circumstances.

A similar circuit could be followed through in which the cam switch 46 when receiving current through the relay contact 32e, FIG. 3, would light the 1G trafiic light and extinguish the light 1 R, and would light the traflic light 2R, but extinguish the light 2G.

The third cam position 47 would be associated with one of the other cams shown at the right end of the cam shaft in dotted lines in order to provide a left-turn signal or some other more complicated function.

Thus, rec-apitulating, when the relay 30 closes along with one of the other relays, such as the relay 31, the circuit through the automatic-manual control switch C is opened and therefore the synchronous timing motor no longer controls the pulsed power to the ratchet motor M, which power is instead furnished to the motor M through the jack J6 from the contact Q1 of the flash magnet. It the light is red in the preferred direction from which the emergency vehicle is coming, the switch at the auxiliary cam 45 will be closed and the flash magnet Q will be energized so as to cause the lights in the intersection to all change from steady state to flashing. They continue flashing while at the same time the ratchet motor steps the shaft S rapidly around with each breaking of the flasher contacts F. As soon as the shaft S reaches the position such that the one light is red, and the other and preferred light in the intersection is green, the cam 45 opens its associated switch and breaks the flow of current to the flash magnet at the right end thereof. When this happens, the system stops and remains dormant with the light green in the direction of the street from which the emergency vehicle is coming and with the light red on the other street. The situation remains stable as long as the timer 35 in FIG. 3 has not yet finished its operation. When the timer has run its course, it opens its normallyclosed switch 35a, thereby opening the relay 30 which opens the then-closed contacts 30a and breaks the flow of power to whichever one of the relays 31, 32 or 33 has been energized. The whole system is. thereby reset to normal and the automatic-manual switch C is then again connected through the normally-closed contacts 316, 32c and 33c to the ratchet motor so that the actuation of the ratchet motor is controlled by the switches I and R on the synchronous timing motor N. As stated above, the person driving the emergency vehicle may be in a strange portion of the city and therefore may not know which of the buttons to press in order to gain the rightof-way for his vehicle at the next controlled intersection. If he presses the wrong one, he defeats his purpose by making the light turn red against his approaching vehicle. Therefore, the symbols shown at the very top of FIG. 1, and perhaps other or difierent symbols, are provided on the push buttons 2, 3 and 4, and in addition the service poles near the controlled intersection will display discs showing the symbol corresponding with the button which should be depressed in order to gain right-of-way through the particular intersection. As related above, if the light is already green in the preferred direction and the operator depresses the correct button in the emergency vehicle, nothing happens because the cam shaft is already in the right position and remains so because the opening of one of the contacts 31c, 32c or 33c disconnects the ratchet motor M from the automatic-manual switch C. On the other hand, if the light is against the approaching emergency vehicle, then the traflic lights in both directions are caused to flash for an interval of a few seconds while the shaft S steps rapidly around until it reaches the correct position as determined by one of the auxiliary cams 45, 46 or 47. When this occurs, the system stabilizes and remains in this position until the timer 35 opens all of the relays 30, 31, 32 or 33 and returns control of the traffic signal to the synchronous motor M.

I do not limit my invention to the exact 'form shown in the drawings, for obviously changes may be made therein within the scope of the appended claims.

-I claim:

1. A remote-control system for actuating an automatic trafliclight controller to present a go light in a favored direct-ion of travel determined by an emergency vehicle approaching the controlled intersection, said controller having a switching dial rotated by power from a power source and cyclically actuating a stepping motor for stepping around a shaft having rotary switches each controlling one of the traffic lights of said intersection and the controller including rapid light-flasher means, said remote-control system comprising in the vehicle transmitter means for emitting a carrier signal, plural modulation generator means each connected to uniquely modulate the carrier signal to indicate a favored direction of travel, and selective means for applying at least one of said modulations to the carrier signal; and said remote-control system comprising at said controller receiver means for receiving the modulated carrier signal, plural tuned relay means connected to the receive-r and each responsive to the presence of one of said unique modulations to operate a plurality of associated contacts in each relay means, including first normallyclosed contacts coupling the switching dial to the stepping motor and opening to break said coupling when a relay means is actuated, second normallyopen contacts closing when the relay means is actuated to connect the stepping motor to the flasher means to step the shaft around at the rapid flashing rate, third normallyopen contacts connected with said power source and closed when the rleay means is actuated, and separate auxiliary rotary switches each turned by said shaft and associated with a different relay means and each connected between one of said third contact means and the flasher means, each auxiliary switch being open when the shaft is positioned to present a go light in the associate favored direction of travel and closed in other positions, whereby the flasher means is energized only when the shaft is in a position other than that corresponding with the unique modulation energizing the associated relay means.

2. In a system as set forth in claim 1, each modulation generator comprising an audio frequency generator including a tuning-fork stabilized oscillator.

3. In a system as set forth in claim 1, each of said relay means comprising a resonant-frequency sensitive relay tuned to the frequency of one of said modulation generators.

4. In a system as set forth in claim 1, 'an interval timer at the controller and connected to be energized by said relay means; hold-contact means in series with the relay winding of each relay means to hold the latter closed when energized; and contact means on the timer and connected in series with said hold-contact means for opening the relay means at the end of the timed interval.

5. In a system as set forth in claim 4, each relay means representing a unique traffic direction having sets of normally-closed contacts connected in series with the windings of the other relays representing other traffic directions whereby when one of these relay means is actuated the other relay means are disabled.

6. In a system 'as set forth in claim 1, said means for selectively applying modulation to the carrier signal in cluding push-lbuttons each having switch means for connecting one of the modulation generators to the transmitter means when the push-button is pressed and then released; and dash-pot means coupled with each pushbutton and slowing the return rate thereof when released to provide the transmitted signal with suflicient duration to operate the receiver means.

7. A remote-control system for actuating an automatic trafiicli-ght controller to present a go light in a favored direction of travel determined by an emergency vehicle approaching the controlled intersection, said controller having a switching dial rotated by power iron].- a power source and cyclically actuating a stepping motor for stepping around a shaft having rotary switches each controlling one of the trafi'ic lights of said intersection and the controller including rapid light-flasher means, said remotecontrol system comprising in the vehicle transmitter means for emitting a carrier signal, plural modulation generator means including a coding generator for connecting the controller for remote control and plural direct-ion identifying generators each connected to uniquely modulate the carrier signal to indicate a favored direction of travel,

and selective means for applying the modulations from said coding generator and from one of said identifying generatiors to the carrier signal; and said remote control system comprising at said controller receiver means for receiving the modulated carrier signal, plurm tuned relay means connected to the receiver and each responsive to the presence of one of said modulations to operate a plurality of associated contacts in each relay means, the relay means responsive to the coding modulation having contacts for enabling energization of the other tuned relay means and the latter each including first normally-closed contacts coupling the switching dial to the stepping motor 0 and opening to break said coupling when a relay means is actuated, second normally-open contacts closing when the relay means is actuated to connect the stepping motor to the flasher means to step the shaft around at the rapid flashing rate, third normally-open contacts connected with 5 said power source and closed when the relay means is actuated, and separate auxiliary rotary switches each turned by said shaft and associated with a different relay means and each connected between one of said third contact means and the flasher means, each auxiliary switch 0 being open when the shaft is positioned to present a go light in the associate favored direction of travel and closed in other positions, whereby the flasher means is energized only when the cam shaft is in a position other than that correspondmg with the unique modulation energizing the associated relay means.

8. In a system as set forth in claim 7, each modulation [generator comprising an audio frequency generator ineluding a tuning-fork stabilized oscillator.

9. Ina system as set forth in claim 7, each of said relay means comprising a resonant-frequency sensitive relay tuned to the frequency of one of said modulation generators.

10. In a system as set forth in claim 7, an interval timer at the controller and connected to be energized by said code-modulation responsive relay means; hold-contact means in series with the relay winding of each relay means to hold the latter closed when energized, and contact means on the timer and connected in series with the hold-contact means on the code-modulation responsive relay means for opening the relay means at the end of the timed interval.

11. In a system as set forth in claim 10, each relay means representing a unique tratfic direction having sets of normally-closed contacts connected in series with the windings of the other relays representing other traflic directions whereby when one of these relay means is actuated the other relay means are disallrled.

12. 'In a system as set forth in claim 7, said means for selectively applying modulation to the carrier signal including push-buttons each having switch means for connecting one of the modulation generators to the transmit- -ter means when the push-button is pressed and then released; and dash-pot means coupled with each pushbutton and slowing the return rate thereof when released to provide the transmitted signal with sufiicient duration to operate the receiver means.

13. In a system as set forth in claim '12, the switching means associated with each push-button having two circuits, one circuit at each switching means energizing the coding generator and the other circuit energizing a unique direction identifying genera-tor each time the button is depressed and released.

14. A remote-control system for actuating an automatic traffic-light controller to present a go light in a favored direction of travel deter-mined from a remote position observing the controlled intersection, said controller having a switching dial rotated by power from a power source and cyclically actuating a stepping motor for stepping around a shafit having rotary switches each controlling one of the traflic lights of said intersection, said remotecontrol system comprising at the remote position a. transmitter for emitting a carrier signal and including plural modulation means each seleotible to uniquely modulate the carrier signal to indicate a favored direction of travel; and said control system comprising at said controller pulsating means; receiver means for receiving the moduiated carrier signal, plural tuned modulation-sensitive means connected to the receiver and each responsive to the presence of a unique modulation to operate a plurality of associated contacts in each tuned means, including first normally-closed contacts coupling the switching dial to the stepping motor and opening to break said coupling when a tuned means is actuated, second normally-open contacts closing when the tuned means is actuated to conncct the stepping motor to the pulsating means to step the shaft around at a rapid rate, third no-nnrally-open contacts connected with said power source and closed when the tuned means is actuated, and separate auxiliary rotary switches each turned by said shaft and associated with a different tuned means and each connected between one of said third contact means and the pulsating means, each auxiliary switch being open when the shaft is positioned to present a go light in the associate favored direction of travel and closed in other positions, whereby the pulsating means is energized only when the shaft is in a position other than that corresponding with the unique modulation comprising the associated tuned means.

References Cited in the file of this patent UNITED STATES PATENTS 3,020,522 Lcsher Feb. 6, 196 2

Claims (1)

14. A REMOTE-CONTROL SYSTEM FOR ACTUATING AN AUTOMATIC TRAFFIC-LIGHT CONTROLLER TO PRESENT A "GO" LIGHT IN A FAVORED DIRECTION OF TRAVEL DETERMINED FROM A REMOTE POSITION OBSERVING THE CONTROLLED INTERSECTION, SAID CONTROLLER HAVING A SWITCHING DIAL ROTATED BY POWER FROM A POWER SOURCE AND CYCLICALLY ACTUATING A STEPPING MOTOR FOR STEPPING AROUND A SHAFT HAVING ROTARY SWITCHES EACH CONTROLLING ONE OF THE TRAFFIC LIGHTS OF SAID INTERSECTION, SAID REMOTECONTROL SYSTEM COMPRISING AT THE REMOTE POSITION A TRANSMITTER FOR EMITTING A CARRIER SIGNAL AND INCLUDING PLURAL MODULATION MEANS EACH SELECTIBLE TO UNIQUELY MODULATE THE CARRIER SIGNAL TO INDICATE A FAVORED DIRECTION OF TRAVEL; AND SAID CONTROL SYSTEM COMPRISING AT SAID CONTROLLER PULSATING MEANS; RECEIVER MEANS FOR RECEIVING THE MODULATED CARRIER SIGNAL, PLURAL TUNED MODULATION-SENSITIVE MEANS CONNECTED TO THE RECEIVER AND EACH RESPONSIVE TO THE PRESENCE OF A UNIQUE MODULATION TO OPERATE A PLURALITY OF ASSOCIATED CONTACTS IN EACH TUNED MEANS, INCLUDING FIRST NORMALLY-CLOSED CONTACTS COUPLING THE SWITCHING DIAL TO THE STEPPING MOTOR AND OPENING TO BREAK SAID COUPLING WHEN A TUNED MEANS IS ACTUATED, SECOND NORMALLY-OPEN CONTACTS CLOSING WHEN THE TUNED MEANS IS ACTUATED TO CON-

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