WO2012062941A1

WO2012062941A1 - System for natural lighting by optical waveguiding and light extraction, applied to buildings

Info

Publication number: WO2012062941A1
Application number: PCT/ES2011/000318
Authority: WO
Inventors: Daniel Vazquez Molini; Antonio Alvarez Fernandez-Balbuena; Berta Garcia Fernandez
Original assignee: Universidad Complutense De Madrid
Priority date: 2010-11-11
Filing date: 2011-10-27
Publication date: 2012-05-18
Also published as: ES2384737A1; ES2384737B1

Abstract

The invention relates to an optical system for transporting natural light into a building, formed by a hollow guide (3) having a peripheral layer formed by two types of prismatic plastic sheets performing guiding and extraction functions, without additional geometric elements. The light guiding sheet (30) is such that the edges of the prisms face outwards and are parallel to the longitudinal axis of the guide, and the sheet (40) that performs the extraction functions is such that the edges of the prisms face outwards and are parallel to the longitudinal axis of the guide. The amount of light extracted in a determined position of the guide can be regulated by means of the increase or decrease in the area of the extraction sheet.

Description

Natural lighting system by optical guidance and light extraction applied to buildings

OBJECT OF THE INVENTION The present invention relates to an optical system that allows the interior of a building to be illuminated with natural light by means of a guidance system for said natural light. It is part of the technical sector of lighting in buildings.

BACKGROUND OF THE INVENTION

Since in September 1881 W. Wheeler in US247229 patent develops a lighting system based on light guides, numerous guidance and light extraction systems have been described.

When we focus on the hollow light guides covered by prismatic sheets to efficiently conduct the light through internal reflections of the material we find, for the first time, the concept introduced by Whitehead, subsequently continuing with numerous patents in which related ideas are developed of this same inventor.

In US4260220 the concept of a hollow longitudinal guide of light with a structure of transparent dielectric material, which can be acrylic plastic or optical glass, is introduced to transmit or conduct light from a central source to a remote location. The light guide includes four flat walls, forming a rectangular parallelogram, which have an internal flat surface and an external surface with 90 ° prisms. The light guide may have a coating to protect the dielectric material from damage. In US4850665 a method is shown to reflect the light through a portion and with a selected angular inclination with respect to the guide. In relation to the prismatic sheet used in these guidance systems we find beginnings in US4906070 and US5056892 patents of Sanford Cobb, where a structure with a series of isosceles prisms and whose geometry can be manipulated to control the light output path is described .

This film has numerous utilities thanks to its flexibility and the total internal reflection suffered by the light on its surface and numerous examples of usefulness can be found in its use in the field of solar energy and as a light conduit. Subsequently, in US6285814 a light guide composed of a longitudinal housing with an internal surface where smaller sections of optical prismatic sheet are housed is described. The luminaire may include extractor elements to reflect the light outside the guide.

In US6481882 a lighting development is exposed to distribute the light with an extractor system that extends towards the inside of the guide and projects the light from the inner surface towards the inside of the guide, releasing the light through the walls of said guide.

Patent US6796686 shows how the temperature varies according to the color of the light emitted by a hollow prismatic light guide, approaching its appearance towards a redness caused by the passage of the rays through the dielectric material of which the guide is composed of light. This material absorbs the short wavelengths of the visible spectrum. The prismatic guide is partially covered with an opaque material with a reflective internal surface and a light emitting aperture. One or more light diffusers placed along the internal surface of the system allow varying the direction of the rays. The material's color filter absorbs the wavelengths belonging to the blue zone by varying the output results based on the distance traveled in the guide. One technique to avoid the perception in the change of color is to vary the color of the extractor according to the length of the guide. The inclusion of a filter at the exit of the light would compensate for the redness in the appearance of the color of the light without a significant reduction in the luminance characteristics of the luminaire.

In "Principal New Hollow Light Guide system" Heliobus "for Day lighting and Artificial Lighting of Central Zones I heard Multi Storey Buildings" by J.B. Aizenberg and patent CH690788A5 show the development and prototype results, in real size, of vertical light guidance with prismatic laminate incorporating a stationary heliostat at the top and cylindrical extractors of different diameters along the guide.

The present invention is clearly different from what can be found in the state of the art. Although the elements that make up the invention separately are already known, however, only the proposed configuration allows to obtain a product with utilities and functions clearly different from those proposed to date. The use of a prismatic extraction blade with its vertices inwards and the prisms developed in the transverse direction of the light guide makes it possible to obtain a product with improved characteristics such as: - the possibility of regulating the amount of light that is extracted at a certain position of the guide by increasing or decreasing the area of the extraction sheet;

- the possibility of arranging the entire system in a sandwich structure which facilitates the assembly and maintenance of the system;

- it is not necessary to introduce foreign elements into the interior space of the light guide to extract the light;

- the angle with which the light is extracted allows it to be directed towards those positions that do not produce glare. DESCRIPTION OF THE INVENTION

The proposed invention (Figure 1) is a lighting system with natural light from buildings composed of the following elements: a collection system (1), a randomizing element (2), a light guide (3), various extraction elements (4), several glare and / or redirection control screens (5), a closing system at the bottom (6) and another at the top (7).

This system is based on the combined use of two types of prismatic plastic sheets (figure 7). The guide sheet (30) performs the function of guiding the light and has the edges of the prisms outwards (20) and parallel to the longitudinal axis of the guide. The extraction sheet (40) performs the functions of extraction and has the edges of the prisms towards the inside (10) of the guide and perpendicular to the longitudinal axis of the guide.

The collection system (1) consists of a device that allows maximum flow capture inside (10) of the guide (3), while directing it in the right direction and providing it with the necessary opening. This element may consist of heliostats or passive collection elements. Although it is not an essential element, it is advisable to increase the level of flow used. Given the transmission characteristics of the guide, the opening of the beam that is introduced into the guide must be less than the maximum angle for which there is confinement within the guide, according to the prisms of the guide itself. The direction in which the light is introduced is recommended that it is not parallel to the axis of the guide so that, contrary to what happens with systems that work on specular reflection, the maximum number of reflections occurs and therefore improves the uniformity and distribution of light.

The light guide (3) has in its upper part a closure (7), generally made of glass or transparent plastic material to prevent, first, the entry of dirt and, secondly, that it works as a shot in case of fire . W

However, given that it is a vertical tube, it is possible, if this is taken into account in the project, taking the appropriate security measures, that the tube works as a natural shot that helps to cool the building as it is done in The traditional Muslim architecture.

5 In this case it will be essential to provide for the internal cleaning of the vertical pipe. Although in the proposed scheme the channeling is vertical, there is no limitation with its direction which can also be horizontal or even inclined.

The randomizing element (2), which spatially and angularly standardizes the guided beam, consists of a refractive or specular system that allows the light coming from the sensor to a wider range of directions, so that it is distributed from the beginning of the Guide to all directions of the building.

The light guide (3) is the element that transmits the light throughout the building. Se5 is a hollow volume so that the light does not have to be propagated by a dense element with the absorption losses that this entails. This also makes it possible for the flow that is capable of driving the guide to be very high since it does not have an inlet surface on which, upon passing to the dense medium, heating occurs which deteriorates and ages said material. 0 The walls of the guide (3) are formed by a plastic sheet of prismatic section (30), with axes parallel to the longitudinal axis of the guide (3), and in which the edges meet towards the outside (20) of the guide thus leaving the smooth surface inwards (10).

These prisms are usually 90 °, although with other angles they can also confine the light, so they work just as the well-known Porro prism does, as shown in Figure 4. The light on their impact is reflected. , because the light tries to move from a medium with a higher refractive index to a lower one, from one side to the other. Therefore the light in the guide (3) travels through the air and only when it reaches the skin of the guide is it when it enters the dielectric medium.

This makes absorption losses very low. On the other hand, the efficiency of the guide will be conditioned by the radii of curvature that join the various faces that make up the prismatic surface (30) since, when the face is not perfectly flat, light can escape from the system. However, in this case the existence of a certain loss due to this effect is considered as something beneficial since it is diffuse light that will increase the sensation of luminosity of the tube, without dazzling.

The extraction of the light from the guide is produced by replacing in the extractors (4) the previous prismatic sheet (30) with another (40) that has the prisms in different orientation. In this case, the prisms instead of being arranged in the longitudinal direction of the guide, as in the previous case, are arranged in a transverse direction. In addition, the smooth face now, instead of being oriented towards the inside (10) of the guide, is disposed towards the outside (20), thus leaving the edges of the prisms inwards.

With this arrangement, the light when the light strikes a face of the prism deviates and leaves the outside of the guide, as shown in Figure 5, with the angle of the prisms determining the direction of exit. By calculating predetermined dimensions, the required output flow is controlled. These dimensions may vary both in size and location according to the needs required in each space.

The extraction elements (4) may optionally be glare control and / or redirection screens (5).

To facilitate the assembly and maintenance of the system, the guiding (30) and extraction (40) sheets can be placed in a sandwich structure, (figure 9) in which the prismatic transparent sheet is coated in the inner area (10 ) and in the outer zone (20) with two transparent sheets Extraction systems are located at the top or bottom to avoid glare, although this is not limiting.

The lower closure system (6) incorporates a mirror or J eam splitter in the lower part of the guide so that the light beam is reflected upwards increasing the amount of light transmitted by the guide and in the opposite direction to sunlight.

In a more particular way, additional elements are incorporated in the hollow the central part, therefore, incorporating elements that are deemed appropriate in each case: another light guide (50) with different geometries such as cylindrical, quadrangular, polygonal, triangular expanding the possibilities of extracting light throughout the guide according to the required needs. (Figure 8).

DESCRIPTION OF THE DRAWINGS

For the best understanding of what is described herein, some drawings are attached in which the object of the present invention is described.

Figure 1 shows a lighting system with natural light from buildings with a pick-up system (1), a randomizing element (2), a light guide (3), extraction elements (4), glare control screens and / or optional redirection (5) and closing system (6). Figure 2 shows the cross section of the guide.

Figure 3 shows the three-dimensional design of the guiding sheet.

Figure 4 shows the behavior of a ray of light when passing through the prismatic sheet with a certain angle undergoing internal reflections on the surface of the material. Figure 5 shows the behavior of a beam of light through the prismatic sheet (40) of extraction with a certain angle and suffer refraction in The surfaces of the prism.

Figure 6 shows the three-dimensional design of the extraction sheet.

Figure 7 shows the structure composed of a guide sheet (30) that performs the function of guiding light and has the vertices of the prisms outward (20) and longitudinal to the axis of the guide, and an extraction sheet (40) that performs the extraction functions which is composed of transverse prismatic blades with the vertices inwards (10) of the guide.

Figure 8 represents an embodiment in which the system is arranged so that in its central internal part (10) another sheet (50) is placed with symmetrical guiding prisms with respect to the outer guide (30) and is, therefore, a hole to incorporate another light guide with cylindrical geometry.

Figure 9 shows the sandwich panel structure formed by a transparent prismatic sheet (30) and coated in the inner zone (10) and in the outer zone (20) with a transparent coating (70). EMBODIMENT OF THE INVENTION

A light guide of 2 m in diameter and 16.7 m in length has been made, crossing a four-story building. Each floor is 3.85 m high and the height between floors is 0.3 m.

Two circular circular heliostats with a diameter of 0.9 m were placed as capturing elements (1) of sunlight.

The light guide sheet (30) used was a polycarbonate sheet with right angle prisms, 90 ° degrees.

The light extraction sheet (40) used is also a polycarbonate sheet but this time with 70 ° angle prisms. Two 0.5 m long bands of this extractor sheet were incorporated into the top and bottom of the guide section that ran through floors 1 ^or 2 ^or the building.

The closure system incorporates an Miro 20 type aluminum mirror.

Claims

1. Natural lighting system by optical guidance and light extraction applied to buildings comprising: a collection system (1), a randomizing element (2), a light guide (3), various extraction elements (4) , several glare and / or redirection control screens (5), a closing system at the bottom (6) and another at the top (7) and characterized in that it allows natural light to be transported inside a building through the hollow light guide (3) and without additional geometric elements.

2. Natural lighting system by optical guidance and light extraction applied to building according to claim 1 characterized in that the walls of the light guide (3) are formed by a prismatic sheet (30) of axes parallel to the longitudinal axis of the guide and in which the edges of the rush are towards the outside (20) of the guide.

3. Natural lighting system by optical guidance and light extraction applied to buildings according to claims 1 and 2, characterized in that the prisms are of an angle such that they allow the light to be confined and work as Porro prisms.

4. Natural lighting system by optical guidance and light extraction applied to building according to claims 1 characterized in that the light extracting elements (4) are formed by a prismatic sheet (40) of axes perpendicular to the longitudinal axis of the guide and the edges of the prisms facing inwards (10) of the guide (3).

5. Natural lighting system by optical guidance and light extraction applied to building according to claims 1 and 4 characterized in that when the light strikes a face of the prism of the extraction sheet it deflects and goes outside the guide.

6. Natural lighting system by optical guidance and light extraction applied to building according to claims 1, 2, 3, 4 and 5 characterized in that the sheets of the guidance system and those of extraction are incorporated into a sandwich panel in a assembly that allows modulating the amount of light extracted according to the needs of the premises.

7. Natural lighting system by optical guidance and light extraction applied to building according to claims 1, 2, 3, 4 and 5 characterized in that the system incorporates in its central part a perimeter sheet with symmetrical guiding prisms with respect to the exterior and forming another light guide.