FR2498786A1 - Traffic light control system - uses single power supply cable with local interface containing microprocessor at each set of lights - Google Patents

Abstract

The system includes a single pair of power transmission lines running from the supply to a local controller at each set of lights. A main microprocessor control unit is linked to each local control unit via one pair of information transmission lines. The lights themselves may be incandescent bulbs, or fluorescent lamps operated via transformers. The transformers are then of light weight (500g - 1kg) and provide the necessary 1500 volt output. Each of the lamps is controlled by a triac, which is controlled by signals from the control unit. The arrangement is lighter in weight than the 50 Hz transformers necessary for the control of lights in the conventional way.

Description

Traffic light system
The present invention relates to a traffic light system consisting in particular of three-colored lanterns turned on and off according to periods worked out in a control cabinet and transmitted to the lanterns by transmission means.

 Up to now, the supply and control of the crossroad lights has been carried out by a central cabinet controlling the four crossroad lights, for example, by means of at least four times four power wires transmit 220 volts, 50 hertz interrupted or activated by switches such as triacs, thyristors or transistors forming part of the central cabinet.

If we consider re the relatively large distance between the central cupboard and each of the corners of the crossroads, the classic system requires an expenditure in cables of important power.

 In addition, the lights can be fluorescent and not only incandescent in order to space maintenance work on the lanterns, the life of fluorescent tubes being significantly higher than that of incandescent lamps. Fluorescence tubes require incorporated transformers to operate, in order to raise the voltage to 1500 volts, for example.

 However, in conventional systems the frequency of use is 50 Hertz which leads to large transformers.

 The traffic light system according to the present invention overcomes these various drawbacks. In this one, in fact, the number of power and control cables is much lower than in conventional systems, the connection of the lights is simplified and in the case of the use of fluorescent tubes their transformers can be smaller. In all cases, fluorescent or incandescent tubes, the light actuator housed in the central cabinet has a smaller footprint than in conventional solutions.

 The present invention relates to a traffic light system comprising a plurality of traffic lights arranged at the appropriate places of a crossroads and a control cabinet comprising a central light actuator, characterized in that the lights are supplied with energy by a single power line, each light being associated with a local actuator comprising an interface optionally equipped with microprocessors, said local actuators being controlled by a single independent transmission line transmitting orders from said control cabinet.

 According to a feature of the invention, the transformers of said fluorescent tube traffic lights (R, J, V) are each supplied by an inverter receiving a direct voltage rectified by a diode bridge from the power line, said inverter carrying its output voltage at a frequency of a few thousand hertz and operating on the command of a transmission interface receiving its orders from said transmission line, each of said interfaces, said diode bridge and the three inverters constituting said local actuator.

 According to another particular feature of the invention, incandescent lamps constituting said lights are each supplied by said power line through a triac operating on command of a transmission interface receiving its orders from said transmission line each of said interfaces and the three triacs constituting said local actuator.

 With reference to the attached diagrammatic figures 1 to 3, an example of implementation of the present invention will be described below, an example given purely by way of illustration and in no way limiting. The same elements represented in several of these figures bear the same references on all of them.

 FIG. 1 represents a diagram of the energy supply and of the control of the lights of a crossroads.

 FIG. 2 represents a wiring of a light whose lantern is with fluorescent tube.

 FIG. 3 represents a wiring of a light whose lantern is with an incandescent lamp.

 We see in Figure 1 a crossroads consisting, for example, of the crossing of two tracks 1 and 2. At the corners of the crossroads are arranged three-color lights such as 3 and local actuators such as 4 associated with signals 3. Local actuators 4 are supplied with energy by a power line 5 coming from the single-phase sector 220 volts 50 Hertz or possibly a three-phase voltage. This line goes around the crossroads and generally consists of a two-wire cable. The local actuators 4 are controlled by means of a transmission line 6 transmitting the orders addressed to each of the actuators 4 from a control cabinet 7. In its simplest version, the transmission line 6 consists of two conductors of the telephone line type going around the crossroads. It is obvious that this transmission line 6 can be replaced by a radio or optical link.

The transmission line 6 may have a larger number of conductors if the transmission system adopted makes it necessary and it is possible to double it by its own power supply which would allow the control circuits to be completely decoupled from the circuits of power.

 We see in Figure 2 a traffic light 3 with red lanterns R, yellow J, green V fluorescent tubes. 220 volts - 1500 volts step-up transformers such as 31 are each housed in the body of the lantern. These transformers are small and each weigh, for example, from 500 grams to 1 kilogram against 3 kilograms of a conventional transformer operating at 50 hertz from previous control systems. Indeed the local actuator 4 housed in the barrel of the support of the light 3 comprises an electronic system for transforming energy from the power line 5 consisting of a diode bridge 41 rectifying the alternating voltage of the line 5 and supplying a plurality of inverters 42, 43 with direct voltage, 44 corresponding respectively to the red, yellow and green lanterns and providing a high frequency alternating current voltage (for example a few thousand hertz). The actuator 4 also comprises a transmission interface 45 supplied by the transmission line 6. The switching on and off of each of the tubes R, J, V is controlled by the starting or stopping of each of the inverters 42, 43, 44.

This starting or stopping is triggered by a signal emitted by the transmission interface 45 which can be implemented in wired logic and include microprocessors.

 The interface of the transmissions 45 recognizes the orders which interest it, decodes them and retransmits them. The interface 45 is connected to the central controller, which may or may not be a microprocessor> from the control cabinet 7.

 The interface 45 can also be responsible for responding to the interrogations emitted by the central control unit by sending back a message by the transmission line. It can in particular report a local incident which is taken into account by the microprocessor of the central controller and displayed to eliminate any search.

 Starting or stopping the tube with low current information saves the light actuator housed in the central cabinet. This becomes smaller and more economical compared to the previous systems where the starting and stopping were carried out by control of the power lines.

 The transmission interfaces 45 can also be responsible for transmitting the information coming from vehicle detectors placed near the support, which provides great flexibility and economy of installation.

 In Figure 3 we see an alternative embodiment with incandescent lamp lights, red, yellow, green 32, 33, 34.

 The local actuator 4 is then less complex than previously, the inverters being replaced by triacs 46, 47, 48 controlled by the transmission interface 45.

 The control system according to the present invention allows savings to be made in traffic control installations while increasing performance. It is particularly suitable for lanterns with fluorescent tubes. The invention is in the field of traffic control systems.

Claims (3)

1 / Traffic light system comprising a plurality of traffic lights (3) arranged at the appropriate locations of a crossroad (1, 2) and a control cabinet (7) comprising a central light actuator, characterized in that the lights are supplied with energy by a single power line (5) each light being associated with a local actuator (4) comprising an interface (45) optionally equipped with microprocessors, said local actuators being controlled by a transmission line (6) single independent transmitting orders from said control cabinet (7). 2 / light system according to claim 1, wherein said traffic lights (3) are fluorescent tubes (R, J, V) equipped with transformers, characterized in that each of said transformers is powered by an inverter (42, 43, 44) receiving a direct voltage rectified by a diode bridge (41) from the power line (5), said inverter (42, 43, 44) bringing its output voltage to a frequency of a few thousand hertz and operating on command of a transmission interface (45) receiving its orders from said transmission line (6), each of said interfaces (45) said diode bridge (41) and the three inverters (42, 43, 44) constituting said local actuator (4). 3 / light system according to claim 1, wherein said traffic lights (32, 33, 34) are incandescent lamps characterized in that they are each supplied by said power line (5) through d '' a triac (46, 47, 48) operating on command of a transmission interface (45) receiving its orders from said transmission line (6) each of said interfaces (45) and the three triacs (46, 47, 48) constituting said local actuator (4).