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Publication numberUS3825890 A
Publication typeGrant
Publication dateJul 23, 1974
Filing dateJul 17, 1970
Priority dateJul 17, 1969
Publication numberUS 3825890 A, US 3825890A, US-A-3825890, US3825890 A, US3825890A
InventorsFujii M, Miyazato T, Nakayama K
Original AssigneeHattori Tokeiten Kk
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Control system for a traffic signalling apparatus
US 3825890 A
Abstract
A traffic signalling apparatus having green, yellow and red signal lamps is controlled by a control system comprising a standard signal generator source having a constant high frequency output and a time cycle generator for generating time signals. A receiving circuit periodically receives a broadcast wave serving as a reference frequency source and appropriate frequencies are selected and used to compensate for frequency variations occuring in the time cycle generator. The control system may include a programming device whereby a programmed time cycle pattern of operation of the various colored signal lamps may be selectively changed at certain times of the day to most effectively control the traffic flow. The programming device may be used in conjunction with a series of traffic lights to variably stagger the operation of successive traffic lights in dependence upon changing traffic conditions.
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nited States Patent [191 Miyazato et al.

[ CONTROL SYSTEM FOR A TRAFFIC SIGNALLING APPARATUS [75] Inventors: Takanori Miyazato; Keiichi Nakayama, both of Tokyo; Masao Fujii, Koube, all of Japan [73] Assignee: Kabushiki Kaisha Hattori Tokeiten,

Tokyo, Japan 22 Filed: July 17,1970

21 Appl. No.: 55,929

[30] Foreign Application Priority Data July 23, 1974 Primary Examiner-Kathleen l-l. Claffy Assistant Examiner-Randall P. Myers Attorney, Agent, or FirmRobert E. Burns; Emmanuel J. Lobato; Bruce L. Adams [5 7] ABSTRACT A traffic signalling apparatus having green, yellow and red signal lamps is controlled by a control system comprising a standard signal generator source having a constant high frequency output and a time cycle generator for generating time signals. A receiving circuit periodically receives a broadcast wave serving as a reference frequency source and appropriate fre- July 17,1969 Japan... 44-56325 quencies are Selected and used to compensate for [52] U 8 Cl 340/40 340/41 R quency variations occuring in the time cycle genera- [51] Gosg 1/085 tor. The control system may include a programming [58} Fie'ld I40 41 35 device whereby a programmed time cycle pattern of operation of the various colored signal lamps may be lectivel chan ed at certain times of the day to most [56] References Cited Se y g v effectively control the traffic flow. The programming UNITED STATES PATENTS device may be used in conjunction with a series of 3,015,802 1/1962 Newsom 340/40 traffic lights to variably stagger the operation of Successive traffic in upon 3,175,193 3/1965 Willyard et al...... 340/40 traffic conditions 3,483,508 12/1969 Cress, Jr. et al. 340/40 I 3,594,719 7/1971 Endo et al. 340/40 10 Claims, 9 Drawing Figures A 3 4 2 s ;4@ n s ggfigfl'i 1 PRIM. SEC. i TRAFFIC l DIVIDER DIVIDER S|G.APP. 08 C. l I

i V6 J n s RESET TlMER SELECTO AMPLIFIER C|RCU|T i W RECEIVER PAIEIIIEIIIIIIw 3.825.89

SHEET 1-ur 4 I i I 3 4 q T 2 5 1 I40 Y 5 S QuARTz PRIM. SEC. i TRAFFIC gggN- I DIVIDER DIvIDER I I sIeAFR l A J 8 F N7 REET TIMER J-SELECTO AMPLIFIER C|RCU|T -+REcEIvER 5 FIG 2 II I4 A l2 l3 I L fi GEAR TRANS- i TRAFFIC T 1 4] I v f l8 fl? ELECTRO- TIMER SELECTOR AMPLIFIER M G I \I IET IC +RECElVER The present invention relates to control systems in general and more particularly, to a control system for a traffic signalling apparatus.

Traffic lights employing red, green and yellow signal lamps are well known and typically comprise a signal generator connected through suitable cable to a plurality of traffic lights each having timing and switching mechanisms to thereby control the time cycle pattern of signal indication of the colored signal lamps. These conventional control systems are disadvantageous in that the positioning of the cable either underground or strung in the air is very expensive and hence, any defect in the signal generator source necessitating a removal of the cable is very costly. In addition, any signal generator defectv will temporarily place all the traffic lights out of order until the signal generator is repaired.- Sometimes the frequency output of the signal generator drifts or varies causing erratic operation of the traffic lights and necessitating timely repairs accompanied by shutdown of the traffic lights.

It is frequently desirable to vary the time duration during which each colored signal lamp remains lighted in accordance with variations in the traffic flow. In other words, as traffic congestion builds up on one roadway much more so than on another roadway controlled by the same traffic light, it is desirable to increase the time duration which the green signal lamp remains lighted on the busier roadway and correspondingly increase the time duration which the red signal lamp remains lighted on the other roadway which has a much lighter traffic load. The sequential lighting of the green, yellow and red signal lamps and the combined time duration of one cycle is referred to as the time cycle pattern of signal indication and it is this parameter which should be varied in accordance with various traffic'pattems. Conventional control systems cannot automatically change the time cycle pattern of signal indication, but instead, when the traffic becomes very crowded or erratic, the time cycle of signal indication is manually controlled.

Whena plurality of traffic lights are successively disposed along a roadway, it is often desirable to stagger the operation of each successive traffic light to ensure a a smooth flow of traffic. In other words, it is often desirable to lengthen the time from the indication of a green signal from one traffic light to the next sucessive indication of a green signal from the next adjacent traffic light and this time difference between the indications of successive green signals (or other similarly colored signals) is called the offset time of signal indication. Thus, it can be seen that it is desirable to increase the offset time of signal indication of a series of traffic lights when traffic flow is slow or crowded in order to provide a smooth traffic flow. The particular offset time is determined in accordance with the mean speed of the automobiles and the distance between successive traffic lights. In the conventional control systems, the successive traffic lights are lit in accordance with a certain delay time which is determined by a time delay device provided in the particular traffic light itself, and the delay time cannot be varied in accordance with variations in the traffic flow.

The present invention provides a new and improved control system for a traffic signalling apparatus and eliminates many of the aforementioned disadvantages of the conventional control systems for traffic lights.

According to the present invention, the sequential lighting period for a series of the traffic lights is accurately maintained by providing means for periodically and automatically compensating for frequency variationsin a frequency converting means.

According to one aspect of the present invention, there is provided a control system for a traffic light having green, yellow and red signal lamps which comprises control means for generating a standard signal at a constant high frequency. A frequency converting means is provided for converting the standard signal into a time cycle signal representative of a predetermined time cycle pattern of signal indication to be applied as an input signal to the traffic light whereby the green, yellow and red signal lamps are sequentially lighted in accordance with the predetermined time cycle pattern. Means are provided for receiving a broadcast wave containing a reference time signal and regulating means is provided for correcting or regulating frequency drift occurring in the frequency converting means in response to this time signal. Thus, the time accuracy of the traffic light is maintained by means of the reference time signal contained in the broadcast wave.

According to another aspect of the present invention,

' there is provided a control system for a traffic light which comprises frequency converting means for converting thestandard signal into a plurality of time cycle signals having different time periods each corresponding to a different time cycle pattern of signal indication, and programming means for selecting the different time cycle signals in accordance with a predetermined program. Thus, three different time cycle signals are sequentially applied to the traffic signaling apparatus in accordance with a preselected program whereby the green, yellow and red signal lamps are lighted in different time cycle patterns of signal indication. One time cycle pattern of signal indication is defined as the time from the indication or lighting of the green signal lamp through the lighting of the yellow and red signal lamps to the lighting of the green signal lamp again and such may be lengthened or shortened when the traffic flow either increases (congestion) or decreases (light traffic) whereby a smooth traffic flow may be obtained.

According to a further aspect of the present invention, there is provided a control system for a traffic signal which comprises in addition to the aforementioned features, a plurality of traffic lights each having control means including frequency converting means for converting the standard generator signal into a plurality of different time cycle signals each having a phase difference corresponding to a different offset time of signal indication which may be required at a plurality of different times depending upon the particular traffic flow pattern. A programming means is provided in each control means for selecting any one of the plurality of different time cycle signals as an input signal to be applied to the traffic signaling apparatus at the previously programmed time. Thus, when a series of traffic lights are positioned along a roadway at certain distance intervals, the offset time of signal indication between the successive traffic lights may be lengthened when the It is therefore one object of the present invention to provide a control system for a traffic light which does not require any cables and which maintains the time accuracy of the time cycle pattern of signal indication by means of a broadcast wave reference time signal.

It is another object of the present invention to provide a control system for a traffic light which includes means for changing the time cycle pattern of signal indication in accordance with predetermined traffic flow patterns.

It is a further object of the present invention to provide a control system for controlling a plurality of successively disposed traffic lights which includes means for changing the offset time of signal indication of the signal lamps between successive traffic lights disposed along a roadway in accordance with predetermined traffic flow patterns.

The above and other features and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a block diagram of a control system for a traffic light according to the present invention having a quartz crystal oscillator for generating a standard signal;

FIG. 2 is a block diagram of a control system for a traffic light according to another embodiment of the present invention having a vibrator for generating a standard signal;

FIG. 3 is a block diagram of a control system for a traffic signal according to an embodiment of the present invention having a quartz crystal oscillator for generating a standard signal and a programming device;

FIG. 3A is a wave form representation of three different time cycle signals having different time cycles to be supplied to the traffic light in accordance with a program;

FIG. 4 is a block diagram of a control system for a traffic light according to another embodiment of the present invention having a standard signal generator using a commercial power source and a programming device;

FIG. 5 is a block diagram of a control system according to the present invention for a plurality of traffic lights;

FIG. 5A is a graph showing the relationship between the traffic flow and the offset time of signal indication;

FIG. 5B is a waveform representation of three different sets of time cycle signals having phase differences therebetween to be supplied to three different traffic lights.

FIG. 6 is a wave representation of time cycle signals having both time cycle differences and phase differences therebetween.

FIG. 1 schematically discloses a traffic signal control system 1 of the local traffic controller type for controlling the operation of a traffic signalling apparatus 2. The control system comprises a quartz crystal oscillator 3 which generates a high frequency standard signal and the output of the oscillator is delivered to a frequency converting means 4. The frequency converting means 4 comprises a primary divider circuit 4a and a secondary divider circuit 4b connected to one output of the primary divider circuit 4a.

The primary divider circuit 4a divides the high frequency standard signal received from the quartz crystal oscillator 3 and delivers the divided signal to the secondary divider circuit 4b. The secondary divider circuit 4b then divides the divided signal into a time cycle signal representative of the desired time cycle pattern of a signal indication for the signal lamps within the traffic signal apparatus 2. The time period during which one colored signal lamp is on relative to one complete time cycle of operation of the traffic signal apparatus is known as the dividing ratio and the particular control circuitry for performing this function is well known in the art and therefore need not be further discussed here.

The primary divider circuit 4a and the secondary divider circuit 4b are each composed of one or more conventional bistable multivibrators, tristable multivibrators and blocking oscillators arranged in a well known manner to form a frequency dividing circuit. The selection of the particular dividing frequency is determined in accordance with the dividing ratio of the desired time cycle pattern of signal indication, which, of course, is selected in dependence upon the existing traffic flow pattern. The output signal from the secondary divider circuit 4b represents the desired time cycle of operation of the traffic signal apparatus 2. Thus, the different colored signal lamps in the traffic signal apparatus 2 are sequentially lighted in accordance with the time cycle signal.

From the above it can be readily understood that any variations in the output of the frequency converting means 4 will accordingly vary the time cycle signal applied to the signalling apparatus 2 thereby distorting and changing the desired time cycle pattern of signal indication. According to the present invention, any frequency drift or variation occurring in the frequency converting means 4 is corrected by adding a time reference signal to the frequency converting means 4.

A receiver 5 of well known construction, such as a radio receiver, receives a standard radio (audio frequency) or television (video frequency) broadcast wave w which is periodically transmitted by commercial stations as a reference time signal or reference frequency signal. The receiver 5 is normally in a nonworking mode and a timer is connected to the receiver and operates to place the receiver in its receiving mode at the time period the time signal information contained within the wave w is broadcast. The timer is of conventional construction and functions to place the receiver 5 in condition to receive the broadcast wave prior to the time the reference frequency signal is transmitted. As shown in FIG. 1, an output of the primary divider 4a is connected to the timer. A frequency selector 6 comprising a well-known filter is connected to receive the time signal delivered from the receiver 5 and the selector 6 selects or detects the appropriate time signal information contained in the wave w. The time signal output from the selector 6 thus represents a correction or regulating signal which is amplified in an amplifier 7 and delivered to a reset circuit 8. The reset circuit 8 resets the primary and secondary divider circuits in accordance with the regulating or correction signal to thereby correct counting errors in the frequency converting means 4. This ensures that the individual green, yellow and red signal lamps of the traffic signal apparatus 2 always continue to accurately operate in accordance with the predetermined time cycle pattern of signal indication.

In operation, the traffic signal apparatus 2 is suitably programmed with well known control circuitry to control the time cycle of operation of the red, green and yellow signal lamps in response to the application of the time cycle signal. In normal operation, the time cycle signal delivered by the secondary divider circuit 4b is delivered to the traffic signal apparatus 2 and the control circuitry then sequentially controls the lighting of the red, green and yellow signal lamps in accordance with the predetermined time cycle pattern of signal indication. To ensure consistency and accuracy of the time cycle signal delivered by the frequency converting means 4 to the signal apparatus 2, the output of the frequency converting means 4 is periodically monitored by a reference time signal contained in the broadcast wave w.

Another embodiment of the present invention is shown in FIG. 2. In this embodiment, the control system 11 comprises a vibrator 13, such as a balance, tuning fork, etc., which functions as a standard signal generator and which includes a frequency regulating mechanism to regulate or adjust the output frequency thereof. A frequency converting means 14 comprises a gear train 14a mechanically coupled to the vibrator l3 and a transducer 14b for converting the mechanical motion of the gear train 14a into an electric time cycle signal.

In operation, the vibrating motion of the vibrator 13 is converted into rotary motion by the gear train 14a while simultaneously undergoing a speed reduction, and the transducer 14b converts the rotary motion into an electric time cycle signal representative of a predetermined time cycle pattern of operation for the signal lamps contained within the traffic signal apparatus 12. As in the above mentioned embodiment, the traffic signal apparatus 12 contains control circuitry which is programmed to control the time cycle pattern of the green, yellow and red signal lamps. The transducer 14b may comprise a cam for opening and closing an electric contact, a photoelectric device, a pressure responsive mechanism or a magnetic responsive device.

In this embodiment, the frequency converting means 14 is selectively varied by an electromagnetic driving device 18 which may, for example, be of the well known plunger type. The receiver 15, the selector l6 and the amplifier 17 are analogous to and function the same as the corresponding components shown in FIG. 1.

When it is desired to monitor the vibrator output, the broadcast wave w is received by the receiver 15 and the appropriate reference frequency information contained therein is selected by the selector 16 and amplitied by the amplifier 17 and delivered as an amplifier regulating or reference signal to the electromagnetic driver 18. The electromagnetic driver 18 then drives or adjusts the regulator mechanism of the frequency converting means 14 as well as regulating the gear train 14a in accordance with the reference or regulating signal.

FIG. 3 discloses a control system for a traffic signal apparatus which is basically similar to that disclosed in FIG. 1 but which includes a programming device 29 for selectively changing the time cycle pattern of signal indication of the traffic signalling apparatus in accordance with 'the traffic flow conditions. The frequency converting means 24 coacts with the programming device 29 to form a time cycle generating means for generating different time cycle signals, as described hereinafter. In this embodiment, the secondary divider circuit 24b divides the time cycle signal received from the primary divider 24a into three different time cycle signals each representative of a particular time cycle pattern for operating the individual signal lamps in accordance with three distinct traffic flow patterns. These three different timecycle signals are shown in FIG. 3A wherein signal S, has a time cycle T, of 50 seconds, signal S has a time cycle T of 60 seconds, and signal S has a time cycle T lasting seconds.

The programming device 29 includes an amplifier 29a receptive of each of the three different time cycle signals delivered from the secondary divider circuit 24b for amplifying these signals and delivering them to a programming board 29b, which may be a conventional pin board. An amplifier 290 is connected to another output from the primary divider circuit 24a and delivers an amplified and primarily divided signal to a program transfer device 29b, such as a rotary solenoid switch. The program transfer device 29b is connected to the programming board 29b and selectively chooses the particular time cycle signal 8,, S or S, which is to be delivered to the traffic signal apparatus 22.

By way of example, the signal S, may represent a desired time cycle pattern which is to be used at a particular intersection between 9 pm. and 8 am. of the following day, the signal 8, represents a different time cycle pattern which is to be used from 9 pm. to 6 pm, and the signal 8,, represents yet another time cycle pattern of signal indication which is to be used between 6 pm. and 8 am. These various signals are selectively applied to the traffic signalling apparatus 22 in response to operation of the program transfer device 29d. Thus, the time cycle of signal indication may be selectively varied three times every 24 hours in accordance with the information contained in the programming device 29. The receiver 25, the selector 26, the amplifier 27 and the reset circuit 28 perform the same function as their counterparts disclosed in FIG. 1.

FIG. 4 discloses another embodiment of the present invention which comprises a control system 31 for controlling the operating characteristics of the traffic signalling apparatus 32. The control system 31 comprises a commercial power source 33 driving a frequency converting means 34 which comprises a synchronous motor 34a connected to rotationally drive a gear train 34b which is connected to a transducer 340 for converting the rotary mechanical motion into an appropriate electric time cycle signal. In this embodiment, the rotary motion of the synchronous motor 34a is converted into three different electric signals by the transducer 340 and each electric signal represents one time cycle signal for a particular pattern of operation of the traffic signalling apparatus 32. The transducer 34c may comprise any of the devices described in reference to the embodiment shown in FIG. 2. A battery power source may also be connected to the synchronous motor 34a cooperating with a switching relay such that a power failure of the commercial power source 33 will effect switching of the relay so that the control system 31 will continue to function.

The programming device 39 comprises a programming board 3% electrically connected to receive the three different time cycle output signals from the transducer 34c. A programming transfer device 39d comprising, for example, a rotary switch, is mechanically connected to the gear train 34b and electrically connected to the programming board 39b. The programming board 3% selectively receives the three different time cycle signals in accordance with the angular position of the rotary switch making up the programming transfer device 39d which is rotationally driven by the gear train 34b. Hence, each of the time cycle signals are applied to the traffic signalling apparatus 32 at different time intervals in accordance with the information set in the programming device 39 as in the embodiment shown in FIG. 3. The receiver 35, the selector 36, the amplifier 37 and the electromagnetic driver 38 correspond to their respective components shown in FIG. 2.

A plurality of traffic lights may be provided, as shown in FIG. 5, wherein each of the control systems (identified by A, B and C) correspond to the system shown in FIG. 3. With such an arrangement, it is possible to change the offset time of one traffic light relative to the other traffic lights to achieve a properly staggered pattern of operation of the various traffic lights in response to varying traffic flow conditions. The offset time is defined as that time period between the actuation of one colored signal lamp in one traffic signalling apparatus and the actuation of the same colored signal lamp in the next succeeding taffic signalling apparatus.

FIG. 5A shows the relationship between the traffic flow along a particular road, the distance between three successive traffic signals, and the offset time of signal indication. The ordinate represents the distance between three successive traffic signals A, B and C and the abscissa represents the offset time. Three mean speeds of traffic flow v,, v and v are graphically shown in FIG. 5A wherein v represents the slowest speed and v the fastest speed. Considering first the condition existing when the mean speed v of the traffic is relatively slow, the offset time of signal indication of the traffic signals A, B and C are a,, b and c respectively. When the traffic flow increases such that the mean speed becomes v the offset time of signal indication of the traffic signals A, B and C are represented along the abscissa by a b and respectively. When the mean speed of the traffic flow increases to v,,, the offset time of the signal indication of the respective traffic signals A, B and C becomes a b and c The waveform of the signal to be selectively supplied to the aforementioned traffic signals A, B and C is determined on the basis of the graph shown in FIG. 5B. The three signals S S and S to be selectively supplied to the traffic signal A each have the same time cycle T and have respective phase shifts correspond ing to the offset times 41,, a and a shown in the graph. The three signals S S and S to be selectively applied to the traffic signal B each have the same time cycle T and have respective phase shifts corresponding to the offset times (b -a (b -a and (b -a Similarly, the three signals S 1, S and S to be selectively supplied to the traffic signal C each have the same time cycle T and have respective phase shifts corresponding to the offset times (c -b (c -b and (c -b In this embodiment, the time cycle T T and T are all equal.

Referring back to FIG. 5, which shows one example of a control system for the three traffic signals 42A, 42B and 42C, the control means 41A, 41B and 41C provided in the respective traffic signals are substantially the same as the control system shown in FIG. 3.

One difference is that each control means 44A, 44B and 44C of the respective control means converts the signal from its associated quartz crystal oscillator into three time cycle signals each having the same time cycle pattern of signal indication. For example, the control means 44A, 44B and 44C produce three respective sets of time cycle signals S S and S S S and S and S S and each having a phase shift corresponding to the offset time represented on the above graph.

In operation, when the traffic flow is very light and the vehicles can therefore move relatively fast, the programming device 49A selects the signal S the programming device 49B selects the signal S and the programming device 49C selects the signal S During periods when the traffic flow has increased, the programming device 49A selects the signals S the programming device 49B selects the signal S and the programming device 49C selects the signal S When the traffic flow is at its maximum and the vehicle speed is accordingly very slow, the programming device 49A selects the signal S the programming device 49B selects the signal S and the programming device 49C selects the signals S The programming devices are programmed in a correlated manner similar to the programming of the FIG. 3 embodiment, i.e., on a 24-hour cycle. Thus, the traffic signals 42A, 42B and 42C vary their offset time of signal indication with respect to the adjacent traffic signals in three, separate time durations preselected in accordance with three different traffic flow conditions.

The reference numerals 43A, 43B, 43C, 45A, 45B, 45C, 46A, 46B, 46C, 47A, 47B, 47C, 48A, 49B, and 48C represent structure which is substantially the same as the corresponding structure shown in FIG. 3.

A traffic control system will now be described for changing both the offset time of signal indication and the time cycle pattern of signal indication in a plurality of traffic signals successively disposed along a roadway. For explanatory purposes only, such will be described with reference to a traffic system having three traffic signals as depicted in FIG. 5. The control means provided in the respective traffic signals is substantially the same as the control means shown in FIG. 3. However, the respective counter means of the control means converts the signal from the quartz crystal oscillator into three different time cycle signals each representative of a different time cycle pattern of signal indication with respect to the others. In addition, the control means further convert the aforementioned three different time cycle signals into three different time cycle signals having phase shifts corresponding to a desired offset time of signal indication as done in the aforementioned embodiment. The three different time cycle signals produced by the respective control means 44A, 44B and 44C are shown in FIG. 6 as S S and S S S and S and S S and S These signals are produced from the respective control means on the basis of the graphical representation shown in FIG. 5A as a standard. The signals S S. and S have different time cycles T T and T respectively, different from each other and have phase shifts corresponding to the offset times a,, a and a;,, respectively. The signals S S and S have different time cycles T T and T respectively, different from each other and also have phase shifts corresponding to the offset times(c -b (o -b and (o b respectively. The time cycles T T and T are all equal'to each other, the time cycles T T and T are all the same, and the time cycles T T and T are each equal to each other.

In operation, the respective programming devices individually select one of the three different time cycle signals corresponding to the desired time duration and supplies it to its respective traffic signal. Thus, the three traffic signals sequentially operate with three different time cycle patterns of signal indication together with sequentially changing the offset time of signal indication.

Obviously many variations of the disclosed embodiments may be made without departing from the scope and spirit of the present invention. For example, any number of time cycle patterns may be programmed in the programming device and any number of traffic lights may be coordinately controlled.

What we claim and desire to secure by letters patent 1. In a signal apparatus of the local traffic controller type having a plurality of signal lamps and means for cyclically lighting said signal lamps in a predetermined time cycle pattern in response to a time cycle signal applied thereto: standard signal generating means for generating a standard signal; time cycle signal generating means receptive of said standard signal for developing therefrom a time cycle signal having a constant frequency and applying same to said means for cyclically lighting said signal lamps to thereby effect lighting of said signal lamps in accordance with said predetermined time cycle pattern; receiving means normally in a non-working mode and operable when placed in a working mode to receive a broadcast wave containing reference time information and developing therefrom a reference signal; regulating means responsive to said reference signal for resetting said time cycle signal generating means to effectively compensate for frequency variations occurring in-said time cycle signal generating means; and timer means for placing said receiving means in its working mode only at predetermined times when said time cycle signal generating means is to be compensated.

2. A signalapparatus according to claim 1; wherein said time cycle signal generating means comprises frequency converting means receptive of said standard signal for converting same into said time cycle signal.

3. A signal apparatus according to claim'2; wherein said standard signal generating means comprises a vibrator; said frequency converting means comprises a gear train mechanically connected to said vibrator and operative to convert the vibratory motion of said vibrator into a corresponding rotary motion, and transducer means for converting the rotary motion of said gear train into an electric time cycle signal; and said regulating means comprises electromagnetic driving means for effecting regulation of said gear train in accordance with said reference signal.

4. A signal apparatus according to claim 2; wherein said frequency converting means comprises a synchronous motor rotationally driven in response to said standard signal, and transducer means for converting the rotary motion of said synchronous motor into a corresponding time cycle signal.

5. A signal apparatus according to claim I; wherein said time cycle signal generating means includes means for developing a plurality of different time cycle signals each representative of a different time cycle pattern of operation of said signal lamps; and programming means for individually selecting said time cycle signals and applying them to said signal apparatus in accordance with a preselected program.

6. A signal apparatus according to claim 1; including in combination therewith at least one additional signal apparatus having signal lamps, standard signal generating means, time cycle signal generating means, regulating means and receiving means alike those defined in claim 1; wherein each time cycle signal generating means in each signal apparatus includes means for developing a plurality of different time cycle signals each representative of a different time cycle pattern of operation of said signal lamps and wherein the time period of each time cycle signal developed by said time cycle generating means is the same; and programming means for individually and sequentially selecting said time cycle signals from respective ones of said time cycle generating means and applying them to their corresponding signal apparatus in accordance with a preselected program to accordingly vary the offset time of signal indication between corresponding signal lamps in adjacent signal apparatus.

7. A signal apparatus according to claim 1; including in combination therewith at least one additional signal apparatus having signal lamps, standard signal generating means, time cycle signal generating means, regulating means and receiving means alike those defined in claim 1; wherein each time cycle signal generating means in each signal apparatus includes means for developing a plurality of different time cycle signals each representative of a different time cycle pattern of oper ation of said signal lamps and wherein the time period of each time cycle signal developed by said time cycle generating means is the same; and programming means for individually and sequentially selecting said time cycle signals from respective ones of said time cycle generating means and applying them to their corresponding signal apparatus in accordance with a preselected program to accordingly vary the offset time of signal indication and the time cycle pattern of signal indication between corresponding signal lamps in adjacent signal apparatus.

8. In a signal apparatus of the local traffic controller type having a plurality of signal lamps and having means for cyclically lighting said signal lamps in a predetermined time cycle pattern in response to a time cycle signal applied thereto: an oscillator for generating a high frequency standard signal; frequency converting means receptive of said standard signal for converting same into a time cycle signal and applying same to said means for cyclically lighting said signal lamps to thereby effect lighting of said signal lamps in accordance with said time cycle pattern; receiving means operable independently of the application of said time cycle signal to said means for cyclically lighting said signal lamps and receptive of a broadcast wave containing reference time information for developing therefrom a reference signal; and regulating means operable independently of the application of said time cycle sig nal to said means for cyclically lighting said signal lamps and responsive to said reference signal for resetting said frequency converting means to effectively compensate for frequency variations occurring in said frequency converting means.

ent time cycle signals each representative of a different time cycle pattern of energization of said signal lamps and programming means for individually selecting said time cycle signals and applying same to said signal apparatus to effect cyclical energization of said signal lamps in accordance with a preselected program.

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Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4472714 *Jan 21, 1983Sep 18, 1984Econolite Control Products, Inc.Clock synchronization circuit for control of traffic signals
US4481515 *Apr 1, 1982Nov 6, 1984Philmont Electronics, Inc.Coordinator for traffic signal controller
US5703778 *Jun 1, 1995Dec 30, 1997Hitachi, Ltd.Traffic control method for relieving vehicle congestion on parallel roads
US6647361Nov 22, 1999Nov 11, 2003Nestor, Inc.Non-violation event filtering for a traffic light violation detection system
US6754663Nov 22, 1999Jun 22, 2004Nestor, Inc.Video-file based citation generation system for traffic light violations
US6760061Apr 13, 1998Jul 6, 2004Nestor Traffic Systems, Inc.Traffic sensor
US6950789Sep 12, 2003Sep 27, 2005Nestor, Inc.Traffic violation detection at an intersection employing a virtual violation line
Classifications
U.S. Classification340/913, 340/914
International ClassificationG08G1/07, G08G1/082, G08G1/085
Cooperative ClassificationG08G1/085, G08G1/082
European ClassificationG08G1/085, G08G1/082