WO2007000635A1

WO2007000635A1 - An underwater light

Info

Publication number: WO2007000635A1
Application number: PCT/IB2006/001648
Authority: WO
Inventors: Leslie Pereira Gonçalves CAROTO; Edward Beryman Johnson
Original assignee: Opto Enhanced Technologies (Pty) Ltd
Priority date: 2005-06-29
Filing date: 2006-06-20
Publication date: 2007-01-04
Also published as: ZA200705315B

Abstract

An underwater light (10) comprising a housing (12) and a plurality of light sources (14) extending through the housing so that when the underwater light is in use, the at least one light source is in contact with the water. The light sources may be light-emitting diodes (LED) .

Description

AN UNDERWATER LIGHT

BACKGROUND OF THE INVENTION

THIS invention relates to an underwater light, particularly for swimming pools, tubs, Jacuzzis or any illuminated water feature.

Underwater light systems for pools are well known with lighting being either a normal white, yellow or coloured globe.

The use of light-emitting diodes (LED) is also known.

However there are some difficulties when using underwater lights. First of all, the optimisation of the dispersion of the light in the water is difficult. Particularly where coloured lighting is used it is undesirable for the light to form a concentrated beam across the pool with the peripheral edges of the pool being poorly lit.

In addition, when using LEDs, the LEDs can only be driven using certain maximum current or they over heat and start to fail.

The present invention addresses this. SUMMARY OF THE INVENTION

According to the present invention there is provided an underwater light comprising a housing and at least one light source extending through the housing so that when the underwater light is in use, the at least one light source is in contact with the water.

Preferably, the under water light comprises a plurality of light sources.

The light sources may be light-emitting diodes (LED).

The underwater light may further comprise a plurality of LEDs connected to a circuit board located within the housing.

One side of the housing is formed from a material with a plurality of holes therein through which the plurality of LEDs extend.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a perspective view of an underwater light according to the present invention; and

Figure 2 shows a cross section through a part of the underwater light of Figure 1.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring to the accompanying figures, an underwater light 10 comprises a housing 12 and at least one light source 14 extending through the housing 12 so that when the underwater light is in use, the at least one light source is in contact with the water. The light source may be a light emitting diode (LED), incandescent light bulb, halogen lamp, fluorescent light bulb or any other kind of bulb or lamp. These light sources are typically comprised of a light emitting filament, gas or semiconductor device, for example, which is housed in a transparent or translucent cover.

In the illustrated embodiment the underwater light 10 has a plurality of light sources 14 in the form of a plurality of light-emitting diodes (LED).

The LEDs 14 are connected to a circuit board 16 located within the housing 12 as can be more clearly seen in Figure 2.

The operation of the circuit which drives the LEDs will typically drive the LEDs to change colour slowly or quickly, and is based on the following principles:- o Alternating Current supply derived from a step-down Mains transformer, which additionally provides galvanic isolation from the Mains supply. o Rectification of the A.C. supply to obtain a pulsating (half sinusoidal) Direct Current supply o Detection of decay to zero volts of the pulsating DC, which is coincident with the zero-volt crossings of the AC supply. o The zero-volt intervals occur at twice the Mains frequency, and the amount of current delivered to the LEDs during each interval is controlled to determine the intensity of light emitted during the interval. In this way, the intensity of the lamp, or of certain LEDs in the lamp (for example a specific colour or combination of colours) may be controlled during each interval. The gradual increase or decrease of the current supplied to ^'the LEDs with succeeding intervals, permits the gradual increase or decrease in intensity over time, including the gradual change in colour or combinations of colour over time. This method of control is analogous to the well known technique of "Phase Control". o Where it is required to use a plurality of simultaneously illuminated lamps within close proximity (e.g. illumination of a large pool), the lamps are able to remain indefinitely synchronized through any range of colour and/or intensity changes by maintaining a strict reference to the zero-volt crossings of the Mains. o In addition, the circuitry makes use of a light-sensing element to detect the presence of daylight, in order to avoid unnecessary power consumption and unnecessary light emission by the LEDs during daytime. As the LEDs have a finite lifespan, this measure extends the useful life of the lamp.

One side of the housing is formed from a material such as a PVC moulding and waterproof epoxy resin with a plurality of holes therein through which the plurality of LEDs extend.

In practice, the LEDs are mounted on the circuit board and placed within the housing. A resin is then poured over the front of the housing which flows around the LEDs bonding to the LEDs and to the side walls of the housing. This makes the front of the housing water impervious.

It will be appreciated that when the housing is immersed in water, typically mounted in a hole in the wall of a swimming-pool, the LEDs will be in direct contact with the water.

It will be appreciated that existing underwater lights comprise of a light source being one of the above which is then placed in a light fitting with a waterproof cover such as glass separating the light source from the water while at the same time allowing light emitted from the light source to pass through the cover into the water.

Thus, previous underwater lights have a cover over the LEDs, or other light source, and circuitry which prevents the water from being in contact with the LEDs and circuitry. In contrast, the present invention exposes the LEDs directly to the water. This has two significant advantages. Firstly, the direct interface between the water and the LEDs causes the light from the LEDs to be dispersed through the water and this provides an enhanced lighting effect within the water.

Secondly, the water cools the LEDs in operation. Thus, typically LEDs would be able to be driven at 30 mA whilst in the prototype of the present invention it has been found that these can be driven at 100 mA. This means the added advantage of increased light output resulting from higher current above the standard LED current rating can be achieved.

Claims

CLAIMS:

1. An underwater light comprising a housing and at least one light source extending through the housing so that when the underwater light is in use, the at least one light source is in contact with the water.

2. An underwater light according to claim 1 wherein the under water light comprises a plurality of light sources.

3. An underwater light according to claim 1 or claim 2 wherein the light sources are light-emitting diodes (LED).

4. An underwater light according to any preceding claim wherein the underwater light further comprises a plurality of LEDs connected to a circuit board located within the housing.

5. An underwater light according to any preceding claim wherein one side of the housing is formed from a material with a plurality of holes therein through which the plurality of LEDs extend.

6. An underwater light according to claim 5 wherein the material is a waterproof material.

7. An underwater light according to claim 6 wherein the material is an epoxy resin.

8. An underwater light substantially as herein described with reference to the accompanying drawings.