GB2436610A

GB2436610A - Light redirection device

Info

Publication number: GB2436610A
Application number: GB0606248A
Authority: GB
Inventors: Paul Traynor
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-03-29
Filing date: 2006-03-29
Publication date: 2007-10-03
Also published as: GB0606248D0

Abstract

The invention comprises a light redirection device 4c for improving evenness and uniformity of light from fittings by means of redirecting a proportion of the lamp flux, resulting in reduced dark spots and shadows at the lamp ends and intersections where lamps are mounted in continuous arrays. The light redirection device 4c is positioned over or in front of a lamp source at its end regions and redirects the light by refraction via lenses.

Description

I

light redirection device This invention relates to a device for redirection of light from a lamp source.

Linear lamp sources are most commonly used in many concealed lighting applications, including (but not limited to) ceiling / wall coves, ceiling features, pelmets, furniture, shelf displays, luminaires, as a means of providing ambient light or feature lighting. Lamp sources can be white light or any variety of coloured light.

lt is normally desirable to produce the appearance of cpntinuous, even light from such concealed lighting but for any detail involving more then one lamp source, it is common to experience a shadow or dark spot between the lamps.

The subsequent appearance is generally regarded as undesirable, unless a particular intermittent' effect is required. Small or restricted pelmet I cove details are especiafly problematic as the lamp source is necessarily sited close to the surface to be illuminated and thus the light drop-off or dark spots are particularly noticeable.

This problem is usually overcome by overlapping lamps so that the lighting effect is perceived as continuous, but this solution is often not possible where physical space available limits this technique. It is therefore common to install lamps end-to-end' which means there is a significant gap between lamps, which creates dark-spots and shadow. In addition, the detail for which the lighting is constructed will often not be of a standard' lamp length (or multiple thereof) for widely available lamp sources, thereby forcing a compromise of best-fit' lamp source selection and the issue of gaps between lamp ends.

Similar issues are encountered in luminaires designed to provide continuous light, including (but not limited to) types fitted with opalescent or diffuse panels designed to provide a consistent glowing appearance.

To overcome the problems described above, the invention proposes a device which when placed over the lamp source, will redirect a proportion of the light near the lamp ends such that the dark spot I shadow effect is overcome or significantly reduced.

The light redirection device is expected to enhance the lit appearance of many lighting installations and luminaires.

Preferably, the light redirection device will be simple to fit either at initial installation or as a retro-fit accessory for existing installations.

Preferably, the light redirection device will be simple and cost-effective to produce and suitable for a variety of lamp sources, especially linear types, for instance, in the form of a tube or strip, being made from a thermally stable type of plastic or even glass, probably as a single piece per device.

The light direction device may be made from a transparent or translucent I opalescent material as these are expected to provide most suitable dispersion and distribution characteristics.

The invention will now be described solely by way of example and with reference to the accompanying drawings in which: Figure 1 shows a typical installation featuring fluorescent linear lamp sources mounted end-to-end and an approximation of shadow caused; Figure 2 shows an installation as figure 1, but fitted with light redirection devices with an approximation of the improvement achieved; Figure 3 shows an example of fresnel lens technology and typical light redirection characteristics of this type of lens; Figure 4 shows a technical detail of how the light redirection device functions, in this case fitted over a fluorescent lamp.

Figure 1 shows a typical installation without the light redirection devices fitted consisting of fluorescent lamps mounted end-to-end. The main portion of the lamp Ia is providing diffuse continuous illumination but the lamp cap lb and area adjacent to the lamp electrode Ic are unilluminated. Also, the lamp holders Id mean that lamps are positioned further apart. The result of the illuminated sections of lamp being forced apart by this distance is a shadow or dark-spot' le. Depending on the proximity of the surface to be illuminated, the effect of the dark spot will be more or less noticeable, but in typical installations, the appearance is significant.

Figure 2 shows the same typical installation of end-to-end fluorescent lamps as figure 1, except in this example the light redirection devices 2a are fitted.

By use of these devices, light distribution is improved at the point where there is usually no direct light from the illuminated section of the lamp source I a by means of redirecting a proportion of the light near the lamp ends. The dark spot I shadow 2b is substantially reduced by intervention of the redirecting device, allowing the lamp source to be positioned in closer proximity to the surface to be lit, or in a luminaire, a diffuser to be fitted close to the lamp source with a reduction or omission of dark-spot / shadow.

In figure 3, a sketch section shows a typical fresnel lens, which is a common device for changing the direction of light via principles of prisms and refraction. With this type of lens, light 3b enters the rear of the lens 3a and is redirected to a common point of focus 3c. The invention is not a direct application of this type of lens, but the principles of use of small prismatic type lens arrays will be deployed in the proposed light redirection device.

Figure 4 shows an example of how the light redirection device 4c is designed to function when placed over a lamp source. Light is transmitted from the illuminated section of lamp 4a and via intervention of the lens elements. The light 4d leaves the device at such an angle achieved by the device 4c that more light is achieved around and beyond the lamp cap 4b and where applicable, the lamp holder 4e. Note that number of lens elements and angles drawn are indicative for illustration purposes only and are not intended to represent the finished article when the device has been developed.

Claims

Claims 1. A light redirection device for improving the evenness and

uniformity of light from fittings and concealed lighting details by means of redirecting a proportion of the lamp flux, resulting in a reduced dark spot or shadow at lamp ends and at intersections where lamps are mounted in continuous arrays.

2. A hollow cylinder of transparent material according to claim I adapted to fit around or in the region of the end of a fluorescent tube or strip lamp and which is in the form of one or more prisms of a fresnel lens so as to direct light emitted by the lamp in the direction of the end region and thereby provide illumination around the end region of the lamp.

3. A light redirection device according to claim 1, in which the means of redirection is by refraction via lens(es) positioned over the lamp source.

4. A light redirection device according to claim 2, in which the refraction is achieved via a transparent material.

5. A light redirection device according to claim 2, in which the refraction is achieved via a translucent material.

6. A light redirection device according to claim 2, in which the refraction is achieved via an opalescent material.

7. A light redirection device according to preceding claims, in which the redirection device consists a single element and positioned over the lamp source.

8. A light redirection device according to preceding claims in which the redirection device is built-in to the envelope of the lamp.

9. A light redirection device according to claims I to 8, in which the redirection device consists a number of elements or rings and positioned over the lamp source.

lO.A light redirection device according to claims 1 to 8, in which the redirection device consists of a panel and positioned in front of the lamp source.

11.A light redirection device according to claims I to 8, in which the redirection device consists a single discrete element which modifies the light from only one end of the lamp source.

12.A light redirection device according to claims 1 to 8, in which the redirection device consists a single continuous element, which modifies the light from more than one end of the lamp source.

13.A light redirection device according to claims I to 8, in which the redirection device modifies the light from any section of the lamp source.