GB2388396A

GB2388396A - Illuminated traffic bollard

Info

Publication number: GB2388396A
Application number: GB0210675A
Authority: GB
Inventors: Robin Land; John Redmond
Original assignee: Signature Ltd
Current assignee: Signature Ltd
Priority date: 2002-05-09
Filing date: 2002-05-09
Publication date: 2003-11-12
Also published as: GB0210675D0

Abstract

The illuminated traffic bollard comprises a casing 10 and a base unit 20 wherein the base unit includes an array of Light Emitting Diodes (LEDs) 27 arranged so as to illuminate the casing to make it visible to traffic. The LEDs are preferably high flux LEDs and may be mounted on a circuit board that includes a heat dissipation system. The base unit may be formed from metal with the circuit board being in thermal contact with the base unit, and the LEDs may be arranged in a substantially circular configuration around the centre of the base unit. A transformer or regulator may be used to supply power to the LEDs at less than their maximum rated power.

Description

BOLLARD

The present invention relates to an illuminated bollard. It is particularly, but not exclusively, 5 concerned with illuminated traffic bollards.

There are many thousands of traffic bollards on the UK roads. These are used for highlighting on-road hazards such as sharp kerbs, corners, central traffic islands or pedestrian refuges. The traditional design 10 which is prevalent in the UK comprises a reflective casing and a base unit. The base unit includes a fluorescent tube or incandescent bulb as a light source for illuminating the casing in low light conditions, and is normally embedded in the ground. The base unit also 15 includes a protective polycarbonate cover, which may double as a lens for the light source. In the UK, power for the light source is usually supplied from the national grid at 230V.

Fluorescent tube and incandescent bulbs tend to have 20 a limited life span, requiring regular maintenance and replacement. When multiplied across the number of bollards on the roads, this results in a considerable burden on the authority responsible for maintaining these road fixtures.

( Therefore, at its broadest, the present invention provides a traffic bollard having a casing and a base unit, wherein the base unit includes an array of LEDs arranged so as to illuminate the casing to make it 5 visible to traffic.

Preferably the LEDS are high flux LEDs, i. e. have a luminous flux output of at least 10 lumen per LED. More preferably the LEDs have a typical luminous flux output of at least 15 lumen per LED. The LEDs may be in any lO colour, but for visibility reasons are preferably white.

Preferably the LEDs are mounted on a circuit board, and the circuit board acts as a further heat sink e.g. includes heat dissipation means. More preferably the circuit board is also in thermal contact with the base 15 unit of the bollard. If the base unit of the bollard is made from metal, this then acts as a further heat sink.

A particularly preferred mounting of the LEDs is in a circular configuration substantially in the centre of the base unit. This arrangement provides both a minimal 20 heat mounting and achieves good illumination of the casing for the number of LEDs used.

Preferably the LEDs are configured so as to run at less than their rated power, whilst still providing sufficient illumination. More preferably the LEDs are

( configured so as to run at at most 90% of their rated power. More preferably the LEDs are configured so as to run at at most 85% of their rated power.

Whilst the invention has been described in relation 5 to a bollard as a whole, an alternative aspect of the invention includes a kit which can be retro-fitted to existing traffic bollards thereby making bollards as described above.

An embodiment of the invention will now be described 10 in relation to the accompanying drawings, in which: Figs la and lb show a side view and a plan view respectively of a bollard according to the present invention; Fig 2 shows the base unit of a bollard according IS the present invention; and Fig 3 shows the circuitry used in the base unit of a bollard according to the present invention.

Figs la and lb show a typical traffic bollard comprising a casing 10 mounted over a base unit 20. The 20 casing 10 is made from rigid or flexible plastics material such as a polyplastic, and is designed to both exhibit a high degree of reflectivity of incident light, as well as transmit a high degree of light from its interior. The casing 10 is designed to be separate from

( the base unit 20 so that, in the event of a vehicle colliding with the bollard 1, the casing 10 will be knocked off without causing too much damage to the vehicle or to the base unit, and can be easily replaced.

5 The base unit 20 contains the electrical/electronic circuitry, including light source 25 which in the embodiment shown is an array of twelve high flux LEDS 27 such as those supplied by Lumileds Lighting LLC, 370 West Triable Road, San Jose, CA under the LuxeonT brand. The 10 LEDS are arranged substantially circularly around the centre of the base unit. The base unit 20 also includes a strong polycarbonate cover 22, which is translucent, and may also act as a lens for light source 25.

These LEDS are mounted onto a metal e.g. aluminium, 15 core printed circuit board themselves, which may be further mounted in thermal contact with the gear tray (28 in Fig 2).

The casing 10 may also have a traffic sign, such as directional arrow 12, mounted on it to convey information 20 to road users.

The circular arrangement of the LEDs 27 in this embodiment is particularly preferred as giving a good illumination profile, as well as good heat dissipation

( since the LEDs are positioned in a compact arrangement, but are evenly spaced from each other LED.

Fig 2 shows the base unit 20 of bollard 1 in more detail. The base unit includes a casing 23 which is sunk 5 into the ground, and supports one or more gear trays 28.

The electrical/electronic components, such as light source 25, are mounted on the gear tray(s). The gear tray(s) 28 are accessible for maintenance or repair by opening lid 21, at least part of which is a translucent 10 polycarbonate cover 22. The dimensions of the base unit are shown in millimetres.

Fig 2 also shows an alternative arrangement of the LEDS 27 of light source 25, in two rows.

To retro-fit a bollard with the present invention, 15 the gear tray on which the previous light source was mounted can be easily removed and replaced by a gear tray holding the LEDs of the present invention. This gear tray 28 may be specially adapted to provide further conduction of heat away from the LEDs, and even into the 20 casing 23.

By using the gear tray 28 to conduct heat away from the LEDs, a large surface area is provided for heat dissipation.

( Fig 3 is a circuit diagram of an embodiment of the invention. The power is supplied from the mains source 30 at 230v AC. This is stepped down by transformer 32 to a suitable operating voltage for the LEDs 27 which make 5 up light source 25 and rectified by rectifier 34 and capacitor 36. In this embodiment, the LEDs are arranged in two parallel strings of six LEDs each, but it will be appreciated that other arrangements are possible, which may require different transformer arrangements.

10 In order to ensure uniform lighting in the unlikely event of LED failure, each parallel set of LEDs 27 which make up light source 2S may be evenly distributed. For example, with a two set parallel arrangement, each alternate LED in a circular arrangement such as that 15 shown in Fig l is part of an alternate set. In the event of LED failure in one set, the other set will remain illuminated, and although the total light emitted will reduce, the distribution will not be significantly affected. 20 In current bollard base units where fluorescent tubes are used as the light source, maintenance contractors are required to carry out a check on the unit every four months, and change the fluorescent tubes each time. When using high-flux LEDs according to the

( invention, the maintenance requirements can be reduced to a single site visit annually to check all the electrical connections, but the LEDs used in the embodiment (e.g. those as supplied by Lumileds Lighting LLC) are 5 guaranteed to last for a minimum of five or six years (testing has shown that the luminous output falls by less than 30% over 5 years).

Both the lifespan and the heat dissipation of the LEDs can be improved by running them at less than their 10 rated power or current values. For example, using LEDs supplied by Lumiled Lighting LLC, testing has shown that the life of a high flux LED can be extended to a guaranteed 8 years of continuous operation by running at 600 mA compared with a guaranteed 5 years of continuous 15 operation at the rated 700 mA.

This advantage can be incorporated into the retro fit package, for example by fixing the output of the transformer, or can be configured manually for each bollard. 20 It will be appreciated that other LEDs can be used which will fall within the invention, and provide similar advantages in life span and power consumption.

These preferred embodiments have been described by way of an example and it will be apparent to those

skilled in the art that many alternatives can be made that are still within the scope of the invention.

Claims

( CLAIMS

l. A traffic bollard having a casing and a base unit, wherein the base unit includes: 5 an array of LEDs arranged so as to illuminate the casing to make it visible to traffic.
2. A traffic bollard according to claim l wherein said LEDs are high flux LEDs.
3. A traffic bollard according to claim l or claim 2 wherein said LEDs are mounted on a circuit board, the circuit board including heat dissipation means.

15
4. A traffic bollard according to claim 3 wherein the base unit is made from metal, and the circuit board and the base unit are in thermal contact.
5. A traffic bollard according to any one of the 20 preceding claims wherein said LEDs are arranged in a substantially circular configuration around the centre of the base unit.
6. A traffic bollard according to any one of the preceding claims further including a transformer or regulator, which supplies power to the LEDs at less than their maximum rated power.

s
7. A traffic bollard substantially as described herein with reference to the accompanying drawings.