AU2011213851B2 - A dual voltage assembly for a traffic signal lantern - Google Patents

Abstract

A dual voltage assembly for a traffic signal lantern (10) has at least one lamp and a transformer (102) connected to the or each lamp. The transformer (102) has a first tapping (104) for operating its lamp at an input voltage supplied by mains electricity of, say, 240V and a second tapping (106) for operating its lamp at an input voltage equal to or less than a maximum safe touch voltage of, say, 50V. The assembly also includes a switch (108) for allowing a user to select whether the first tapping (104) or the second tapping (106) of the transformer (102) is used. There are first and second terminals (110, 112) adapted to be connected to the transformer (102) and the first terminal (110) is adapted to receive an input voltage supplied by mains electricity and the second terminal (112) is adapted to receive an input voltage equal to or less than the maximum safe touch voltage. Fig.2 Fig.

Description

FIELD OF THE INVENTION

The present invention relates to traffic signal lanterns and, in particular, to a dual voltage assembly for a traffic signal lantern. More particularly, the invention relates to a dual voltage light emitting diode lamp based traffic signal lantern.

BACKGROUND OF THE INVENTION

Traffic signal lanterns have their power supplied by mains electricity, which generally runs at around 240V. However, if a traffic signal lantern happens to be struck and damaged by a vehicle, then live wires within the traffic signal lantern may become exposed. A person who touches a live wire from a damaged traffic signal lantern which runs at 240V may be at serious risk of injury or death from electrocution. For this reason, many jurisdictions are progressively mandating that all traffic signal lanterns are to operate at a voltage equal to or less than the maximum safe touch voltage. The International Electro-technical Commission has determined that the maximum safe touch voltage is 50V. A problem for traffic authorities is whether to install a new traffic signal lantern which operates at the voltage supplied by mains electricity or at a voltage equal to or less than the maximum safe touch voltage, which may thereafter become mandatory in that particular jurisdiction. If traffic signal lanterns which operate at a voltage equal to or less than the maximum safe touch voltage become mandatory, then another problem for traffic authorities is the cost of purchasing and installing new traffic signal lanterns to replace the traffic signal lanterns which operate at the voltage supplied by mains electricity. A problem for manufacturers of traffic signal lanterns is whether to manufacture traffic signal lanterns which operate at a voltage supplied by mains electricity or to manufacture traffic signal lanterns which operate at or below the maximum safe touch voltage, in the anticipation of forthcoming laws to this effect.

The object of the invention is to overcome or substantially ameliorate the aforementioned problems of the prior art, or at least provide a useful alternative.

SUMMARY OF THE INVENTION

According to the present invention there is provided an assembly, comprising: a lamp connected to a transformer having first and second tappings to respectively operate the lamp at a mains input voltage and a safe-touch input voltage; and a manual switch to manually select whether the lamp connects to the first tapping during normal operation of the lamp, or to the second tapping during replacement of the lamp; wherein brightness and output voltage of the lamp are the same irrespective of which of the first and second tappings is selected.

Preferably, the or each lamp comprises a plurality of light emitting diodes. More preferably, the maximum safe touch voltage is 50V.

It is also preferred that the assembly further comprises a neutral third terminal adapted to be connected to the transformer.

In a preferred form, the assembly also comprises a connector adapted to enable the lamp to be removably connected to its terminal.

The assembly may also comprise a fuse for preventing damage to the assembly in the event that the switch is used to connect the second tapping of the transformer to the lamp, but the voltage is input into the first terminal. BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a front view of a traffic signal lantern including an assembly according to a preferred embodiment of the present invention;

Fig. 2 is a rear view of the front section of the traffic signal lantern of Fig. 1;

Fig. 3 is a front view of the back section of the traffic signal lantern of Fig. 1;

Fig. 4 is a close up view of a terminal shown in Fig. 3;

Fig. 5 is a circuit diagram showing a preferred layout of the circuit used in the lantern of Fig. 1; and

Fig. 6 is a close up view of a switch shown in Fig. 2.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Fig. 1 shows a traffic signal lantern 10 which comprises, in this example, a red lamp 12, a yellow lamp 14 and a green lamp 16. The lamps 12, 14 and 16 may comprise a plurality of light emitting diodes. The traffic signal lantern 10 has a front section 18 (see Fig. 2) for supporting the lamps 12, 14 and 16 and a rear section 20 for supporting the front section (see Fig. 3).

The rear section 20 also supports a terminal block 22 (see Fig. 4) comprising a first terminal 24 for receiving voltage at 240V as supplied by mains electricity, a second terminal 26 for receiving voltage at 42V (which is 5 less voltage than the maximum safe touch voltage of 50V as determined by the International Electro-technical Commission), and a neutral third terminal 28 for receiving a neutral voltage for safety purposes. The terminal block 22 has an input side 30 and an output side 32. The voltage is supplied by a traffic control centre (which is not shown in the drawings).

The first terminal 24 comprises a first sub-terminal 34 for the red lamp 12, a second sub-terminal 36 for the yellow lamp 14 and a third subterminal 38 for the green lamp 16. Likewise, the second terminal 26 comprises a first sub-terminal 40 for the red lamp 12, a second sub-terminal 42 for the yellow lamp 14 and a third sub-terminal 44 for the green lamp 16. The neutral third terminal 28 comprises three sub-terminals 46, 48 and 50.

When the lamps 12, 14 and 16 are intended to operate at 240V, a first power input cable 52, a second power input cable 54 and a third power input cable 56 are inserted into the first terminal 24 on the input side 30 of the terminal block 22. When the lamps 12, 14 and 16 are intended to operate at 42V, the first input power cable 52, the second power input cable 54 and the third power input cable 56 are inserted into the second terminal 26 on the input side 30 of the terminal block 22 (see the dotted lines on Fig. 4). A neutral power input cable 58 is inserted into the neutral third terminal 28 on the input side 30 of the terminal block 22. The cables 52, 54, 56 and 58 are fastened in the terminal block 22 by screws, an example of which is screw 60 (see Fig. 4). A first power output cable 62 connects the first sub-terminal 34 of the first terminal 24 to the red lamp 12. Likewise, a second power output cable 64 connects the first sub-terminal 40 of the second terminal 26 to the red lamp 12. A neutral power output cable 66 connects the first sub-terminal 46 of the neutral third terminal 28 to the red lamp 12. The first power output cable 62, the second power output cable 64 and the neutral power output cable 66 are wrapped together in a plastic sheath to collectively form cable 68.

In the same manner, a first power output cable 70 connects the second sub-terminal 36 of the first terminal 24 to the yellow lamp 14. A second power output cable 72 connects the second sub-terminal 42 of the second terminal 26 to the yellow lamp 14. A neutral power output cable 74 connects the second sub-terminal 48 of the neutral third terminal 28 to the yellow lamp 14, The first power output cable 70, the second power output cable 72 and the neutral power output cable 74 are wrapped together in a plastic sheath to collectively form cable 76. A first power output cable 78 connects the third sub-terminal 38 of the first terminal 24 to the green lamp 16. A second power output cable 80 connects the third sub-terminal 44 of the second terminal 26 to the green lamp 16. A neutral power output cable 82 connects the third sub-terminal 50 of the neutral third terminal 28 to the green lamp 16. The first power output cable 78, the second power output cable 80 and the neutral power output cable 82 are wrapped together in a plastic sheath to collectively form cable 84.

The cables 68, 76 and 84 are removably connected to the red lamp 12, the yellow lamp 14 and the green lamp 16 respectively, via connectors 86, 88 and 90 respectively. The connectors 86, 88 and 90 each comprise a lamp subconnector and a terminal sub-connector, such as lamp sub-connector 92 and a terminal sub-connector 94 for the cable 68. The connectors 86, 88 and 90 may be connected by pushing, clicking or twisting the lamp sub-connector 92 and the terminal sub-connector 94 together. The purpose of having connectors 86, 88 and 90 is to allow a user to quickly and easily install or replace the red lamp 12, the yellow lamp 14 and the green lamp 16.

The lamps of a traffic signal lantern may need to be replaced whilst a user is standing on a ladder with traffic passing nearby on the road. The more complicated and time consuming is the process to replace the lamps, the greater is the risk that the user may lose their balance and fall from the ladder or be struck by oncoming vehicles.

Fig. 5 shows a simplified circuit diagram of an assembly 96, according to a preferred embodiment of the present invention. The assembly 96 comprises a lamp 98 removably connected by a connector 100 to a transformer 102. The transformer 102 has a first tapping 104 adapted to operate the lamp 98 at an input voltage supplied by mains electricity, for example at 240V. The transformer 102 also has a second tapping 106 adapted to operate the lamp 98 at an input voltage equal to or less than the maximum safe touch voltage of 50V, for instance 42V. The assembly 96 also comprises a switch 108 (see Fig. 6) for allowing a user to select whether the lamp 98 connects to the first tapping 104 or the second tapping 106 of the transformer 102. The lamp 98 is adapted to have the same brightness and output voltage (for example, 9V), irrespective of the input voltage.

The assembly 96 also comprises a first terminal 110, a second terminal 112 and a third terminal 114, which are all adapted to be connected by cables to the transformer 102. The first terminal 110 is adapted to receive an input voltage supplied by mains electricity. The second terminal 112 is adapted to receive input voltage equal to or less than the maximum safe touch voltage.

The third terminal 114 is neutral voltage for safety purposes.

The assembly 96 also comprises a fuse 116 (see Fig. 6) in order to prevent damage to the assembly 96 in the event that the switch 108 is used to connect the second tapping 106 of the transformer 102 for 42V to the lamp 98, but the voltage is input into the first terminal 110 at 240V.

Various modifications can be made in the details of the design and construction of the present invention without departing from the scope or ambit of the present invention.

Claims (5)

1. An assembly, comprising: a lamp connected to a transformer having first and second tappings to respectively operate the lamp at a mains input voltage and a safe-touch input voltage; and a manual switch to manually select whether the lamp connects to the first tapping during normal operation of the lamp, or to the second tapping during replacement of the lamp; wherein brightness and output voltage of the lamp are the same irrespective of which of the first and second tappings is selected.

2. The assembly of claim 1, wherein the mains input voltage is 240V, the safe-touch input voltage is less than 42V, and the output voltage is 9V.

3. The assembly of claim 1 or 2, wherein the lamp comprises a plurality of different coloured lamps.

4. The assembly of any preceding claim, wherein each lamp comprises a plurality of light emitting diodes.

5. A traffic signal lantern, comprising the assembly of any preceding claim.