US3020522A - Remote control system - Google Patents

Description

Feb. 6, 1962 J. c. LESHER REMOTE CONTROL SYSTEM 4 Sheets-$heet 1 Filed May 22, 1959 s R. Y m m M m w, R V F- m m C M. JV. B 1| 5 Rfitt kwE m *m E Eumm m. QE g R7 mfisbm Feb. 6, 1962 J. c. LESHER REMOTE CONTROL SYSTEM 4 Sheets$heet 2 Filed May 22, 1959 2 3 6k m m n 6k N M N E w E R my 7 ML l m9 5 v C A fi fi mt M -i 0 93 T WE A J Y \Q mm SE28 B v.2 \3 m 5 63 3 s QEMQE v3 k M R!) mw mm mm mm mm m\\ R. h mm mw MK mm: k p x W mQ m H L L RM "mm 5 .Kmwl nw\ I P' vw k u w.w\ e \JKN NAN m R vm l Q N fl J an v \NW N lllll l| Nv(\,|\|..

Feb. 6, 1962 J. c. LESHER REMOTE CONTROL SYSTEM 4 Sheets-Sheet 3 Filed May 22, 1959 m X NW Feb. 6, 1962 J. c. LESHER 3,020,522

REMOTE CONTROL SYSTEM Filed May 22, 1959 4 Sheets-Sheet 4 INVEN TOR.

ATTORNEYS JOHN C L ESHER 3,020,522 REMOTE (IGNTRQL SYSTEM John C. lLesher, Erie, Pa, assignor to llad-(i-Lite, Inc., Erie, Pa, a corporation of Pennsylvania Filed May 22, 1959, Ser. No. 315,158 7 Qiaims. (Ci. 346-33) The present invention relates to remote control systems and more particularly to a remote control system employing a transmitting unit mounted in a vehicle for alternatively controlling the tral'lic lights located at intersections along the path of movement of the vehicle and the lights in a building or enclosure from externally thereof, so that the enclosure may be surveyed by individuals in the vehicle.

In my co-pending application Serial No. 777,340, filed December 1, 1958, for building protection systems, there is described a portable transmitter and a stationary receiver which permits the lights within a building or enclosure to be selectively controlled by the transmitting unit which may be located in a police or fire vehicle upon approach of the vehicle to the enclosure. The transmitting unit described in the aforesaid application has provision for selectively broadcasting one of two carrier frequencies, a first of the carrier frequencies being employed to control receivers located within buildings and a second of the carrier frequency signals being employed toselect receivers utilized to control traffic lights along the path of movement of the vehicle when answering an emergency call. Those receivers which are located Within an enclosure or building are tuned to the first carrier frequency signal while the receivers employed for traffic light control are tuned to the second carrier frequency signal, each receiver being nonresponsive to carrier signals of the other frequency. The aforesaid co-pending application deals primarily With the systems employed for controlling the lights Within enclosures and further to the specific structures of the transmitter and receiver units employed. In accordance with the present invention, there are provided systerns to be employed with the transmitters and receivers of the co-pending application for controlling traffic lights along the route of an emergency vehicle. Several types of systems are contemplated by the present invention and these relate to the specific type of control to be exercised over the traiiic lights at each corner. In one embodiment of the invention, all of the lights at a corner are turned red and an additional blinking signal may also be employed to indicate to all vehicles that an emergency condition exists. In a second embodiment of the present invention, the traflic lights directed in three directions are red and the light controlling traflic proceeding in the same direction as the emergency vehicle is green. A blinking light may also be employed with this embodiment of the invention. In order to permit selection of the particuler light to be green, there is provided at the transmitter a switch for pulsing the carrier signal and a relay is provided at the receiver for controlling a stepping switch in response to the pulsed carrier. The switch sequentially selects various light control circuits until the proper green light has been selected.

See feature of the present invention is a noval stepping switch for effecting such control. This switch comprises a stepping solenoid and a cam which is rotated 90 for each step of the stepping solenoid. Four sets of contacts are provided in each of the 90 positions and these contacts are Wired to the light control system so that, in each position, three lights are red and a fourth light is turned green, the green light selected in each position of the stepping control arrangement being different light controls. point, a visual indicator is actuated.

from that selected by the control mechanism in each of its other positions.

The receiver unit employs, in addition to the afore said relay or solenoid, a further solenoid having a-time delay circuit for delaying the de-energization of the further relay after loss of the carrier signal. The latter relay controls circuits employed to disconnect the lights from the conventional traffic control box and place them under control of the system of the present invention. The

time delay provided in this portion of the control circuit must be substantially greater than the pulsing times employed to step the aforesaid stepping mechanism so that even though a carrier signal is not received during pulsing intervals, the lighting system is not returned to control of the conventional control box. Further, the time delay may be selected such that the lights are retained under control of the system for a predetermined time after passage of the vehicle in order to provide ample time for the vehicle to clear the corner and also to permit further emergency vehicles following the first vehicle to proceed with safety. More specifically, the delay provided by the aforesaid arrangement prevents free flow of traffic during the interval between passage of one emergency vehicle and the approach of a second emergency vehicle sufficiently closeto the trafiic light to assume control thereover before elapse ofthe aforesaid time delay. In accordance with a still further featureof the present invention, the apparatus provides a system for controlling lights on streets parallel toth-e street along which an emergency vehicle is proceeding. In an'emergency vehicle is proceeding along the main artery and approaches a further main artery, the tratlic along the further main artery piles up behind the light being controlled since there is no control over traflic flowing into the general area under consideration along the further main artery.

In accordance with this aspect of the present invention, 'the traific light for one or more blocks to either side of the street along which the emergency vehicle is proceeding are turned red against the movement of traffic toward the street being employed by the emergency vehicleand therefore prevents this unusual concentration of trafiic along the further main artery behind the traflic lights being controlled. Such a system, however, must permit an emergency vehicle proceeding along the streets parallel to the street being employed by this first mentioned emergency vehicle to override the control instituted thereby so that this further emergency vehicle may stop all traffic or all traflic except that proceeding in its direction.

Emergency vehicles approaching the corner must be able to rely upon the control atforder by the system of the invention and therefore, tests must be made periodically to test operation of the system. In order to make such testing possible, it must be capable of being accomplished quickly and without interfering with the normal flow o-ftraflic. In accordance. with another aspectof the invention a test circuit is provided which is actuated by a special transmitter located in vehicles of maintenance crews and which tests the receiver circuits up to the actual If the circuit is operating correctly to this It is an object of thepresentinvention to provide a traffic light control system inwhich the trafiic lights at a corner may be controlled from answering an emergency call.

It is another object of the present invention to provide a trafiic light control system which may select any one of arpredetermined plurality of lightin'gconditions at a corner being approached by an emergency vehicle.

It is yet another object of the present invention to provide a traffic light control system employing atransmitter mounted in an emergency vehicle and a receiver associated with the trafiic light system which transmitter and an emergency vehicle 3 receiver permit an individual in the emergency vehicle to take over control of the traffic lights from the conventional traffic light control box and select a predetermined pattern of lights at an intersection being approached by the vehicle.

It is still another object of the present invention to provide a traflic light control system in which an emergency vehicle may not only control lights on the street along which the emergency vehicle is proceeding but may also control the lights on streets paralleling the path of movement of the vehicle.

It is another object of the present invention to provide a trafiic light control system employing a novel stepping switch arrangement for permitting rapid selection of a pattern of lights to be initiated at a corner being approached by an emergency vehicle.

It is still another object of the present invention to provide a test circuit in association with a receiver employed to control trafiic lights which test circuit permits a maintenance vehicle to test the operability of the traflic light control system without afiecting the traflic lights.

The above and still further objects, features and advantages of the present invention will become apparent upon consideration of the following detailed description of one specific embodiment thereof, especially when taken in conjunction with the accompanying drawings, wherein:

FIGURE 1 is a schematic wiring diagram of the transmitter and receiver of the present invention;

FIGURE 2 is a schematic wiring diagram of a first embodiment of the present invention;

FIGURE 3 is a perspective view of a stepping switch employed in the present invention;

FIGURE 4 is a schematic wiring diagram of a second embodiment of the present invention;

FIGURE 5 is a street plan employed in explaining the operation of a third embodiment of the invention;

FIGURE 6 is a schematic wiring diagram of a third embodiment of the present invention; and

FIGURE 7 is a schematic wiring diagram of a test circuit employed for testing the receiving apparatus of FIG- URE 1.

Referring now specifically to FIGURE 1 of the accompanying drawings, there is illustrated in generally schematic form an oscillator, modulator and transmitter generally designated by the reference numeral 1 and a receiver and demodulating apparatus generally designated by the reference numeral 2, these elements being illustrated in FIGURES 1 and 4 respectively of the aforesaid co-pending application. The modulator, oscillator and transmitter apparatus 1 is employed to transmit signals, 1

via an antenna 3, having a carrier frequency determined by which of two crystals 4 or 6 is included in the circuit of the carrier oscillator. The crystal 4, for example, may be employed when it is desired to control the lighting within a building or other enclosed area while the crystal 6 is employed when'itis desired to control trafiic lights specifically in accordance with the present invention. The modulator and oscillator 1 is provided with operating high voltage via a terminal 7 and a switch 8 which switch may be employed in accordance with the present invention to select which of the traffic lights at a corner being approached will be red and which will be green.

The receiver apparatus 2 illustrated above the dashed line 5 is illustrated in FIGURE 4 of the aforesaid copending application and comprises a conventional superheterodyne receiver 9 which develops an output voltage across a primary winding 11 of a transformer 12 having a secondary winding 13. The secondary winding 13 is connected to a detector circuit generally designated by the reference numeral 14 which develops an output voltage on a lead 16 in response to reception of appropriate signals from the transmitter 1. More particularly, the receiver 9 when employed with a traffic light control system is tuned to the carrier frequency as determined by the crystal 6 and therefore control signals appear on thelead 16 only when the crystal 6 is determining the frequency of oscillation of the modulator and oscillator 1. As in the aforesaid co-pending application, the output lead 16 is connected to a grid 17 of a triode 18 having a grounded cathode 19 and an anode 21 connected through a coil of a relay 22, the contacts of which are not illustrated in this figure of the drawings. The lead 16 is also connected through a de-coupling network comprising resistor 23 and capacitor 24 to a grid 26 of a triode 27 having an anode 28 connected through a gas discharge tube 29 to a 13+ terminal 31. The triode 27 is further provided with a cathode 32 connected through a cathode load resistor 33 to a source of C- potential. The cathode 32 is further connected to ground through a large storage capacitor 34 and to a grid 36 of a triode 37. The triode 37 has a grounded cathode 38 and an anode 39 connected through the coil of a relay 41, the contacts of which are not illustrated in FIGURE 1.

In operation of the circuit, that portion above the dashed line 5 operates exactly as the receiver circuit illustrated in FIGURE 4 of the accompanying drawings in that upon the receipt of a modulated carrier frequency as determinal by the crystal 6, a voltage appears on the lead 16 which renders the triode 18 conductive, thereby energizing the relay 22 and causing it to close its contacts. The voltage on the lead 16 also substantially instantaneously causes the triode 27 to become conductive and apply a voltage across the capacitor 34. After the capacitor 34 becomes sufiiciently charged, the tube 37 is rendered conductive to energize the relay 41 which closes its associated contacts.

Upon discontinuance of reception of carrier signals from the modulator oscillator transmitter 1, the signal on the lead 16 disappears and the lead becomes negative with respect to ground. The tube 18 is rendered non-conductive and the relay 22 becomes substantially instantaneously de-energized and its associated contacts reopen. Concurrently therewith, the tube 27 becomes non-conductive but the tube 37 remains conductive for a period equal to the time constant of the capacitor 34 and the resistor 33 which for purposes of explanation will be considered to be of the order of magnitude of 15 seconds to one and one half minutes for purposes to become apparent subsequently.

Summarizingthe operation of the circuits illustrated in FIGURE 1 of the accompanying drawings, when the crystal 4 is connected in the modulator, oscillator and transmitter circuit 1, a modulated carrier signal is produced on the antenna 3 which may be received by a receiver constituting that portion of the receiver circuit 2 above the dashed line 5. As described in the aforesaid co-pending application, in response to reception of a carrier signal of a frequency determined by the crystal 4, the receiver 2 turns on the lights within a protected enclosure so that persons controlling the transmitter 1, normally officers in a prowl car or firemen upon arriving at the scene of a fire, may investigate the interior of the enclosure without having to enter it in order to turn on the lights. If the crystal 6 is connected in the transmitter circuit 1, the receiver illustrated in FIGURE 1 of the drawings, receives signals and energizes the relays 22 and 41 which are employed in various systems to be described, to control traific lights at intersections being approached by the vehicle in which the modulator, oscillator transmitter 1 is located.

Referring now specifically to FIGURE 2 of the accompanying drawings there is illustrated one specific system in accordance with the present invention for controlling traffic lights at an intersection. More particularly, the system illlustrated turns all lights red except that controlling traflic proceeding in the same direction as the emergency vehicle. Upon the relay 22 being energized, due to the conduction of the tube 18 of FIGURE 1, it closes its associated contacts 42 thereby energizing a coil 43 of a stepping switch 44. The switch 44 in the illustrated embodiment of the invention, comprises a wiper arm 46 adapted sequentially and successively to engage stationary contacts 47, 43, 49, 5t), 51, and 52. The contact 47 is not connected electrically to any further circuit and constitutes a rest position for the stepping switch. The contacts 47 through 51 are connected via appropriate leads to coils 53, 54, 55 and 56 respectively of electromagnetic relays 57, 58, 59 and 60. The contact 52 isconnected to a coil 61 which upon being energized causes the movable contact 46 to be reset so as to engage the unconnected contact 47.

The relays 57 through 60 comprise, in addition to their associated coils, four sets of double throw contacts which are illustrated in detail only with respect to the electromagnetic relay 60. The contacts of the relay 66 include stationary contacts 62, 63, 64 and 65 adapted to be engaged by movable contacts 66, 67, 68 and 69 respectively when the coil 56 is energized. The contacts 66 through 6 are connected together to a lead 71 connected to one AC. input terminal 72, the other AC. input terminal bearing the reference numeral 70. The stationary contacts 62 through 65 of the electromagnetic relay 66 are connected respectively to leads 73, 74, 75 and 76. The lead 73 is connected to a stationary contact 77 of an electromagnetic relay 78 comprising a coil 79 and a series of four double pole, double throw switches 81. The switches 81 comprise movable contacts 82, 83, 84 and 85 which are normally in engagement with stationary contacts 86, 87, 88 and 89. The switch contacts 31 in addtiion include the aforementioned stationary contacts 77 and further stationary contacts 91, 92 and 93 which are normally not engaged by the movable contacts 82 through 85. The movable contacts 83 through 85 are connected to leads 94, 96 and 97 which are connected each to a contact of a different one of the electromagnetic relays 55*, 58 and 57 respectively which correspond to stationary contacts 62 of the relay 60. The movable contacts 82 through 85 are connected respectively to the east, west, north and south green trathc lights at the intersection and the contact stack 81 is employed to switch the control to these lights from a conventional traflic light control circuit 98 and appropriate contacts of the electromagnetic relays 57 through 50. More particularly, the stationary contacts 86 and 87 of the contact stack 81 are connected via a lead 99 to a trafiic light control and the contacts 58 and 89ers connected via lead 191 to the tarfi'ic light control. The control 98 is such that traific light energizing voltages appear alternatively on the leads 99 and 101 during preselected time intervals such as to provide a conventional pattern of green lights at a corner at which the lighting control system is located.

It is seen that if the coil 79 is de-energized and the movable contacts 82 through 85 are in a position illustrated, the traffic lights are connected to the traflic light control 98 and normal operation is obtained. However, if

the coil 79 is energized, the movable contacts 82 through 85 engage the stationary contacts 77 and 91 through93 respectively so that a pattern of voltages are applied to the green lights as determined by the position of the wiper 46 of the stepping relay 44. More particularly, it the contact 46 engages its stationary contact 51, the coil 56 of the electromagnetic relay 6% is energized and the east green light is connected via the movable contact 89 to stationary contact 77 and lead 73 to the stationary contacts 62 of the relay 6t and through the movable contacts 66 to the lead 71 which completes an energization circuit for that green light. All of the other multiplestationary contacts '91, 92 and 93 are connected to electromagnetic relays which are not energized and therefore no voltage is applied to the green lights associated with these contacts and only the east green light in this particular example is energized. Obviously, the particular green light energized is determined by which of the relays 57 through 66 is energized by the stepping electromagnetic relay 44. In accordance with this embodiment of the invention, only one green light is turned on at each corner and red lights are turned on in the north, south and west directions in the example being given. More particularly, the leads 74, 75 and 76 and a further lead 102 of this group are connected to stationary contacts 103, 164, 165 and 106 of a further electromagnetic relay 107 having an energizing coil 108. The relay 107 is provided with movable contacts 109, 110, 111 and 112 which normally engage a further set of stationary contacts 113, 114, and 116. The contacts 113 and 114 are connected together and via the lead 117 to the trafiic light control Q8. The contacts 115 and 116 are connected together and via a lead 113 to the trafiic light control box 93. The movable contacts 199 through 112 are connected respectively to the red lights at the east, west, north and south locations at the intersection and the control box 98 is such that when voltage is applied to the lead 99 which energizes the east and west green lights, a voltage is applied to the lead 118 which energizes the north and south red lights. Similarly, when the lead 161 has a voltage applied thereto, the lead 117 also has the voltage applied thereto, so that under these circumstances, the north and south lights are green and the east and west lights are red. Upon energization of the coil 1% of the relay 167, the movable contacts 169 through 112 are connected to the leads 102 and '74 through 76 respectively and in the example given above when the relay 6% is energized, the leads 74 and 75 and 76 are connected to lead '71 through the contacts of the solenoid 66 so that the north, south and west red lights are energized. Further, the green light in the east position is connected via the contacts 36 and 82 to the lead 73 and via lead 73 to the lead 71 through the contacts 62 and 66. The contact stacks of the relays 57, 58 and 59 are connected with the leads 73, 94, 96 and 97 and 1 .32, 74, 75 and 76 so that upon the energization of each or" these relays one of the green lights is energized and the remainder of the red lights are energized.

The coils 79 and 108 of the relays 7S and 167 and a coil 119 of a further relay are all energized upon the energization of the relay 41 which closes its associated contacts 121 and connects the coils 79, 168 and 119 across the A.C. power leads 70 and 72.

The coil 119 is associated with single polo, double throw contacts 122 including a movable contact 123 and stationary contacts 126and 126. The movable contact 123 normally engages contact 124 and is connected via alead 12.7 to the AC. terminal 7a. The stationary contact 124 is connected via a lead 128 to supply voltage to the. traific light control 98. The stationary contact 126 is connected via a lead 129 to the rotating contact 46- of the stepping solenoid 44. Thus, normally the tralfic'light control is provided with alternating voltage via the contacts 122 but when the coil 119 is energized, lighting voltage is removed from the trafiic light control 98 and is applied to the rum/- able contact '46 of the stepping solenoid 44-.

.In operation, prior to'the appearance of an emergency vehicle in the vicinity of the control receiver and system under consideration, voltage is applied to the tratlic light control box 93 via leads '71 on the-one hand and via leads-127, switch contacts 122 and lead 12%. Upon the appearance of an emergency vehicle which transmits energy to the receiver 9, the relays 22 and at are energized. Considering initially the operation of the relay 411, it closes its contacts 121 and energizes the coils 119, 168 and 175.

The coil 119' causes the switch contacts 122 to remove step the wiper arm 46 into engagement with the appropriate contacts 47 through 51. Initially, the switch 8 is closed which, as previously indicated, energizes the relays 22 and 41, at which time the wiper 46 engages the contact 47. If, in this position, the proper green light is turned on, then further operation is unnecessary for the moment. However, if this is not the desired green light, then the switch 8 is again open and then closed to step the wiper arm 46 to the contact 49. This process is repeated until the arm 46 engages the proper contact. During each interval that the switch 8 is open, the solenoid 41 remains en ergized due to the time delay provided by the storage capacitor 34 and the resistor 33 in FIGURE 1 of the accompanying drawings. As previously indicated, this time delay may be seconds or greater and therefore the delay is to cover the intervals of operation of the switch 8 required to cause the stepping solenoid 44 to step the wiper 46 to the proper contact. After the emergency vehicle has passed the corner at which the lights under consideration are located, the switch 8 may be actuated a sufiicient number of times to cause the arm 46 to engage the contact 52 which energizes the reset coil 61 so that the arm 46 is reset to a position in which it contacts the unconnected contact 47. After the aforesaid predetermined delay which is sufficient to allow the emergency vehicle to clear the cornor, the solenoid 41 becomes deenergized and the traflic light control system returns to normal operation.

The leads 73 and 94 are connected respectively via leads 131 and 132 to capacitors 133 and 134 and through the capacitors to a common lead 136. The lead 136 is connected through a primary winding 137 of a transformer 138 to the AC. terminal 79 so that when either the east or west green light is energized an AC. voltage is developed across the primary winding 37. The transformer 138 is provided with a secondary winding 139 which is connected across telephone lines for purposes to be described subsequently. It should be noted that the connection of the leads 131 and 132 to the leads 73 and 94 is exemplary only and the leads may be connected to any other pair of leads depending upon the specific system with which the apparatus is to be employed.

It will be noted that once an emergency vehicle obtains control of the system illustrated in FIGURE 2 of the accompanying drawings, that another emergency vehicle approaching the intersection cannot take control of the system away from the original vehicle. Once the emergency vehicle first approaching the corner has switched the lights to the desired condition, the solenoid 22 remains energized so that no other vehicle can control its energization and therefore control the energization of the stepping solenoid 44. Thus, once the one vehicle has set the light to permit it to pass the intersection and stop traffic in all other directions, another emergency vehicle approaching the intersection cannot change the lights and this is an indication in itself to the second emergency vehicle that another vehicle is approaching the intersection and has control over the lights. The time delay in de-energization of a solenoid relay 41 facilitates the control by the second emergency vehicle in that the traffic lights are maintained for from 15 seconds to a minute and a half under the control of the emergency system and it is merely necessary for an emergency vehicle approaching from another direction to step the stepping solenoid 44 so that the green light is turned in the proper direction. However, at no time during the interval between the passage of the first emergency vehicle and the obtaining of control by the second emergency vehicle is the traflic light system returned to normal operation and this is an indication to all traflic that an emergency condition still exists at the intersection.

Referring now specifically to FIGURE 3 of the accompanying drawings, there is illustrated a switching arrangement which may be employed to replace the stepping switch 44, the electromagnetic relays 57 through 60, and the reset coil 61 of FIGURE 2 of the accompanying drawings. The switching arrangement comprises a' coil 141 which is adapted to be connected across the contacts 4-2 of the electromagnetic relay 22. The solenoid 141 drives a pawl and toothed wheel ararngement generally designated by the reference numeral 42 which rotates a cam 143 each time the coil 141 is energized. The cam 141 is surrounded by a group of sixteen single pole, single throw sets of contacts, the contacts being arranged in a square about the cam 143 with four contacts on each side. The contacts, such as the contact 144 which are chosen for purposes of illustration, are normally out of engagement with one another until a cam surface 146 engages them at which time the contacts are closed. In the arrangement illustrated in FIGURE 3, the left vertical set of contacts are closed. These contacts 144 are connected as the aforesaid single pole, single throw switches forming part of the electromagnetic relays 57 through 60 of FIGURE 2 and therefore directly control the application of voltages to the leads 73, 94 through 97, 162 and 74 through 76. For instance, the contacts arranged along the right hand side of the cam 143 have their stationary contacts connected to the leads 73, 74, 75 and 76 and have their movable contacts all connected to the lead 71 and perform the same function as the contacts 60 of FIGURE 2. Thus, the contact structure of FIGURE 3 which employs the single cam 16, the sets of contacts, a pawl, a toothed wheel and a single coil 41 replaces all of the elements 43 through 61 of FIGURE 2 of the accompanying drawings.

In accordance with another aspect of the present invention, it may be desirable to have all lights at a corner indicating stop; that is, being red, and in addition, to provide a siren or flasher to indicate to motorists that an emergency condition exists. Under these sets of circumstances all tratfic is stopped except an emergency vehicle. Such a condition also indicates to other emergency vehicles that the light is already under the control of an emergency vehicle and that other emergency vehicles should stop. In this embodiment of the present invention, the contacts 42 of the solenoid 22 are connected in series with a flasher unit or siren across power terminals 147 and 148. Under the control of the switch 8 of FIGURE 1, the siren can be intermittently energized and the same with a light. Alternatively, an automatic flasher unit may be connected in the system so as to provide a constant rate of flashing. The contact 121 of the relay 41 is connected in series with a coil 149 of a solenoid 150 across the power terminals 147 and 143. The relay 150 further includes a four pole, double throw switch arrangement 151. The contacts comprise four movable contacts 152, 153, 154 and 155 which are normally in engagement with stationary contacts 156, 157, 158 and 159. The contact 159 is connected to ground, the contact 158 is connected to the east-west red light lead 160 of the control box 98, the contact 157 is connected to the northsouth red light lead of the box 98 and the contact 156 applies lighting voltage to the lighting circuits of the box 518. The contact 154 is connected to the east-west red lights and the movable contact 153 is connected to the north-south red lights. The contact 152 is connected via a lead 161 to the alternating current input terminal 148. The contact stack 151 further comprises stationary contacts 162, 163, 164 and 165 with the contacts 162 through 164 being connected together and to the movable contact 155. The contact 156 is connected to a flasher unit which is returned to the alternating current input terminal 147. It should be noted that if a siren is employed which is controlled through the contacts 42 of the solenoid 22 the flasher unit associated with the solenoid 150 may be employed. However, if a siren is not to be employed, then the flasher unit associated with the relay 22 or the solenoid 150 may be dispensed with and particularly, the one associated with the solenoid 150 is preferably eliminated.

In operation, upon energization of the solenoid 41, the

lighting voltage lead to the box 98 is broken due to movement of the contact 152 and therefore none of the lights can receive lighting energy from the control box 98. Simultaneously, the north-south and east-west red lights receive energizing voltage through the movable contacts 153 and 154 by becoming engaged with stationary contacts 163 and 164, the stationary contacts receiving lighting voltage from the movable contact 152 of the switch stack 151.

Thus far two embodiments of the invention have been disclosed, one in which a single green light is employed and another in which all red lights are employed. Obviously, the system may be further modified in accordance with the teachings of the present invention and within the skill of one having reasonable knowledge of the art, to include a system in which two green lights and two red lights are employed.

In accordance with a still further embodiment of the present invention, there is provided'a system for controlling the lights not only on the street along which an emergency vehicle is travelling but also along parallel adjacent streets so as to prevent a pile up of trafiic in adjoining areas. More particularly, and reference is now made to FIGURE of the accompanying drawings, if an emergency vehicle is proceeding westalong West Twelfth Street, which is a main artery, it may be desirable to block traffic approaching West Twelfth Street from the north along another main artery such as West Tenth Street. If a number of emergency vehicles such as fire engines are proceeding west on West Twelfth Street, traffic coming from the north will not be able to cross the street for a relatively long period of time. Consequently, traffic will become backed up along the perpendicular streets such as North Broad and North Market Streets. Therefore, it may be desirable to block the flow of trailic into North Broad and North Market Streets between West Tenth and West Twelfth Streets.

Under these conditions and in accordance with another aspect of the present invention, as an emergency vehicle approaches Intersection D at West Twelfth Street and North Market Street and obtains control over the lights at this intersection, the lights at the Intersections B and A at North Broad and West Tenth Street and North Market and West Tenth Street respectively are controlled so that traffic can only flow east and west along West Tenth Street and is stopped from flowing north along North Broad and North Market Streets. Further, such a system must permit an emergency vehicle travelling along West Tenth Street to override the control exercised by the vehicles proceeding along West Twelfth Street so that the emergency vehicle, if it so wishes may cross West Tenth Street.

Referring now specifically-to FIGURE 6 of the accompanyingdrawings a control system is illustrated which is employed in conjunction with the system illustrated in FIGURE 2 in that it receives energy via the telephone lines from the transformer 138 which in turn is energized by the east-west leads of the control system illustrated in FIGURE 2. The telephone lines are connected to a coil 166 of a resonant relay 167 having contacts 168. The contacts 168 are alternatelytopened and .closed at twice the frequency of the incoming energy and are connected through a coil 169 of a further solenoid 171 to a B+ terminal. The contacts 168 are shunted by a holding capacitor 172 .so that the coil 169 remains substantially constantly energized. The relay 171 is provided with normally open contacts 172 which are closed when coil 169 is energized. A stationary contact 173 of the contacts 172 is connected to an AC. terminal 174 via a lead 176 and a movable contact 177 is connected through a coil 178 of a solenoid, having a contact stack 179, to a lead 181 and via the lead 181 to a movable contact 182 of the contact stack 179. The contact stack 179 further includes movable contacts 183 and 184 normally in engagement with stationary contacts 185 and 186 while the movable contact 182 is normally in engagement with a contact 187. The contacts 186 .and 187 are not electrically connected while the contact 188is connected to the second alternating current input terminal 175. The stationary contact 189 is connected via a lead 193 to a'fiasher unit, the circuit of which is completed to the AC. input terminal 174.' In the operation of this portion of the circuit upon energization of the solenoid 17-8 and actuation of the contact stack 179, north-south green lights are disconnected from the control box 98 and have lighting voltage applied thereto via the contact 184 and 191. Concurrently, the movable contact 183 engages the contact 198 and lighting voltageis applied via the lead 188 to the north-south red lights of the system. Thus, if the system is employed with the circuit of FIGURE 2 and in the example illustrated in FIGURE 5, when a vehicle approaches Intersection D from the east and energizes the light at this intersection such that trafiic heading west ha's'a green light, the system of FIGURE 6 is energized so that at the Intersections A and B green lights permit traffic to flow east and west while red lights prevent the trafiic from flowing north and south across these intersections.

As previously indicated, it is necessary to permit an emergency vehicle proceeding along West Tenth Street to override the control provided by the vehicle on West Twelfth Street and in accordance with the present invention, the energizing circuit for the coil 178 is completed through a stationary contact 194 and a movable contact 195, of a contact stack 196 of a solenoid having an energizing coil 197, to the alternating current terminal 175. The coil 197 is energized in response to energization of the solenoid 41 so that upon energization of this solenoid, the coil 197 is energized and alters the position of its contact stack 196. Under these circumstances, the contacts 194 and 195 become disengaged and the energization circuit of the coil 178 is broken so that the contact 179 assumes the position illustrated in FIGURE 6. Therefore, this portion of the circuit no longer has control over the lights and the control is transferred to the contact stack 196. The contact stack 196 is arranged such that all of the red lights are turned on at the intersection being approached by the emergency vehicle and ,at the same time the flasher unit previously supplied via the lead 193 is now supplied from the contact stack 196. Obviously, the contact stack 196 may be arranged in accordance with the circuit of FIGURE 2 or any other desirable circuit providing control over the lights in accordance with a predetermined function.

Referring now specifically to FIGURE 7 of the accompanying drawings, there is illustrated a test unit which may be employed with the receiver circuitry of the present invention. In this embodiment of the invention, maintenance vehicles are equipped with the same transmitter circuit as illustrated in'FIGURE l of the aforesaid copending application except that the modulating frequency rather than being the order of magnitude of cycles may be considerably greater or less as desirable so that the signal, although receivable by the receiver of FIG- URE 1 of the accompanying drawings, does not energize the light control equipment. However, associated with the receiver unit is a test circuit and referring now specifically to FIGURE 7, the lead 16 is further connected to a grid circuit of a triode 198 having resonant filters 199 and 201 connected to its grid and anode circuits respectively. The filters 199 and 201 pass only the modulating signal generated by a maintenance vehicle and this signal is applied to a further triode amplifier 202 and from an output circuit of the triode to a transformer 203. The output voltage from the transformer 203 is rectified by a suitable rectifier 204 to develop a DC. voltage across a storage and filter capacitor 206. The voltage across the capacitor 206 may be coupled to either an indicating meter 207 located at the tratfic light control station or to a relay 209 having a set of contacts 211. When proper modulating test frequency is detected by the receiver, the contacts 211 are closed and energize a battery operated light 212 which may be connected to the light post so that as a maintenance vehicle proceeds down the street, it may test each of the lights and be able to determine whether the apparatus of the invention is operating properly, since if it is, the light 212 is energized. Alternatively, the contacts 211 may be connected in the flasher circuits previously discussed so that the flashers already available may be employed to produce the desired visual indication.

While I have described and illustrated one specific embodiment of my invention, it will be clear that variations of the details of construction which are specifically illustrated and described may be resorted to without departing from the true spirit and scope of the invention as defined in the appended claims.

What I claim is:

1. A remote control system for trafi'ic lights comprising a portable transmitter for alternatively generating first and second modulated carrier waves of different carrier frequencies, a receiver for said first modulated carrier waves, means for establishing a predetermined pattern of illuminated traffic lights, a relay means for disconnecting, when actuated, traffic lights to be controlled from a conventional traffic light control apparatus and connecting said lights to said means for establishing, means for actuating said relay means in response to receipt of said first modulated carrier signal by said receiver, said circuit means including means for maintaining said relay means actuated for a predetermined time after termination of transmission of said first modulated carrier wave said means for establishing including a plurality of further control circuits, each of said further control circuits establishing when energized a different pattern of illumination of the trafiic lights to be controlled, means for pulsing said first modulated carrier waves, and a fast acting stepping relay means responsive to pulses of said first modulated carrier wave for sequentially and successively energizing said further control circuits.

2. The combination according to claim 1 wherein said means for maintaining retains said relay means actuated for a time interval greater than the off-time of said transmitter during pulsing thereof.

3. The combination according to claim 1 wherein said stepping relay comprises a plurality of normally open contacts arranged along four sides of a square with equal numbers of contacts aligned along each side thereof, a cam rotatable about an axis through the center of said square, solenoid means for rotating said cam through 90 upon each energization of said solenoid means, said cam closing all of the contacts along one side of the square in each of its positions.

4. A remote control system for trafiic lights comprising a portable transmitter for producing carrier signals; a first and second receiver for said carrier signals adapted to control tratfic lights at different locations; each of said receivers including means for establishing a predetermined pattern of illuminated trafiic lights, a first control means for disconnecting when actuated trafiic lights to be controlled from a traffic light control apparatus and connecting said lights to said means for establishing, circuit means for actuating said first control means in response to reception of said carrier waves by its associated receiver, and a second control means for establishing when actuated a further predetermined pattern of its associated traffic lights; means responsive to reception of carrier signals by said first receiver for energizing said second control means of said second receiver and means responsive to reception of carrier signals by said second receiver for de-energizing said second control means.

5. The combination according to claim 4 wherein said receivers are located on parallel streets and wherein said predetermined pattern of lights established by said second relay means permits trafiic to flow along one of said streets parallel to the movement of said transmitter along the other of said streets.

6. A remote control system for trafiic lights comprising a portable transmitter for producing carrier signals; a first and second receiver for said carrier signals adapted to control traffic lights at different locations; each of said receivers including means for establishing a predetermined pattern of illuminated traffic lights, a first control means for disconnecting, when actuated, trafiic lights to be controlled from a traffic light control apparatus and connecting said lights to said means for establishing, circuit means for actuating said first control means in response to reception of said carrier waves by its associated receiver, and a second control means for establishing when actuated a further predetermined pattern of illuminated trafiic lights; means responsive to reception of carrier signals by said first receiver for energizing said second control means of said second receiver and means responsive to reception of carrier signals by said second receiver for de-energizing said second control means.

7. A remote control system for traffic lights comprising a portable transmitter for generating a carrier wave alternatively modulated by first and second modulating frequencies, a receiver for said carrier wave, means for establishing a predetermined pattern of illuminated traffic lights, a relay means for disconnecting, when actuated, trafiic lights to be controlled from a conventional traflic light control apparatus and connecting said lights to said means for establishing, circuit means for actuating said relay means in response to receipt by said receiver of said carrier signal modulated by said first modulating frequency, said circuit means including means for maintaining said relay means actuated for a predetermined time after termination of transmission of said carrier wave, said receiver having a test circuit, responsive to said carrier wave modulated by said second modulating signal for producing a visual display indicating reception of said second modulating signal, said means for actuating said relay means being unresponsive to said second modulating signal.

References Cited in the file of this patent UNITED STATES PATENTS 2,203,871 Koch June 11, 1940 2,291,855 Wilcox Aug. 4, 1942 2,881,409 Cook Apr. 7, 1959 2,903,674 Schwab Sept. 8, 1959

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