DE2936295C2 - Lighting device for illuminating a room with a reflective ceiling with daylight - Google Patents

Description

characterized,

that the outer prismatic disc (3) has prisms (32) arranged on the inside without gaps, the longitudinal axes of which run horizontally and parallel to the outer wall (1),
that each prism (32) has a triangular cross-section transversely to its longitudinal axis and is delimited by the outside (31) as a hypotenuse, an underside (321) and a rear side (322) facing the window,
that only the back (322) of each prism is mirrored,

that the underside (321) of each prism with the outside (31) encloses an acute angle (ω) open towards the window opening (11), which is chosen so that rays with an angle of incidence (ß) below a critical angle durvh total reflection on the underside (321) and reflection ar the rear side (322; again deflected outwards, and
that in the window opening (11) an inner prismatic disc (6) with seamlessly juxtaposed prisms is provided, the longitudinal axes of which run parallel to the outer wall (1) and horizontally and which have a triangular cross-section transverse to the longitudinal axis of such a dimension that the outside onto the inner prismatic disc (6) incident light rays are refracted into the room (2) that they are reflected back into the room from the ceiling or a wall element opposite the window and the angle (d) of the light rays in the room - measured below these light rays against the vertical - is equal to or greater than 70 °.

2. Lighting device according to claim 1, characterized in that the angle between the Underside (321) of each prism (32) of the outer prismatic disc (3) and the vertical between 90 ° and 100 °.

3. Lighting device according to claim 2, characterized in that the angle on the one hand between the underside (321) of each prism (32) of the outer prism plate (3) and the vertical and on the other hand, between the rear (322) and the underside (321) is in each case 90 °.

β 4. Lighting device according to claim 1, characterized characterized in that the inner prismatic lens (6) has a flat, vertically extending outer side (61) and their prisms (62) have a horizontally extending upper side (63), and that the angle between this top and the downward sloping bottom is between 30 ° and 45 °.

5. Lighting device according to claim 4, characterized in that the length of the upper sides (63) of the prisms (62) of the inner prismatic disk (6) is between 1 cm and 3 cm.

6. Lighting device according to one of claims 1 to 5, characterized in that the The ceiling (4) of the room (2) has at least one flat or curved inclined surface (44, 45, 46), whose vertical projection faces the window opening (11)

7. Lighting device according to claim 6, characterized in that the vertical projection of several inclined surfaces (44,45,46) is the larger, the greater their distance from the window opening (11)

8. Lighting device according to claim 7, characterized in that the angles of the inclined surfaces are chosen at each point so that the light rays reflected by them form at most an angle (ε) of 45 ° with the vertical.

9. Lighting device according to claim 7 or 8, characterized in that the ceiling (4) between the window opening (11) and the adjacent first inclined surface (44) and between adjacent ones Has inclined surfaces horizontal sections (41, 42, 43)

10. Lighting device according to claim 9, characterized characterized in that the ceiling between each inclined surface (44,45) and a following horizontal section (42, 43) has an inclined rear surface (47, 48), the angle of inclination against the The vertical is greater than that of the adjacent sloping surface (44, 45).

11. Beieuchiuiigseiiinchiung flat one of the claims 1 to 10, characterized in that the cover (4) consists of aluminum with a matt surface.

The invention relates to a lighting device for illuminating a reflective ceiling Room with daylight according to the preamble of claim 1.

In such a lighting device known from DE-PS 5 17 827, the outer prismatic lens can not only the bright zenith but also the sunlight that heats up the room. This light and Sun rays are partly against the ceiling of the room through a reflective plate Partly also reflected in the line of sight of the people in the room. This results in an undesirable high luminance contrast between the window opening and the surrounding wall surface.

The invention is therefore based on the object of providing a lighting device of the type mentioned at the beginning to further educate that on the one hand no direct sunlight can penetrate into the room, on the other hand as far as possible Lots of zenith light with the least possible difference in luminance between the window opening and the surrounding area f'wall is directed into the room.

The solution to this problem according to the invention is characterized in claim 1. After that is the outer prism plate designed so that through it the sunlight up to the highest possible angle of incidence through total reflection is hidden. The zenith light, which strikes at a higher angle of incidence, is reflected by the outer

Prism plate, the reflective plate and an inner prism plate against the ceiling and only from this the workplace reflects: Therefore, the window opening appears from the normal viewing angle in the room people are not significantly brighter than the surrounding wall surfaces. So it will be annoyingly large Luminance contrasts avoided.

The problem of reducing the differences in luminance between the window opening and the surrounding area is true from DE-OS 17 97 168 known It is there by a prismatic disc inserted into a window opening solved with in cross-section sawtooth-shaped prisms that only allow diffuse radiation to pass through, directed radiation however reflected. The bright zenith light is not used here

In CH-PS 1 94 867 lighting devices are described in which the zenith light via deflecting mirrors and / or refractive prismatic plates are directed onto the work table, with a low luminance contrast is achieved between window opening and surrounding walls.

Protection from the sun's rays is known from "Technik am Bau", No. 3, 1977, pp. 291-294 or placed in front of a window opening prisms through which the direct sunlight is reflected. Additionally zenith light is broken into the room. But this is the luminous flux that can be directed into the room small, because the angle of incidence of the zenith light, measured against the vertical window plane, is very large. That has in addition to the fact that part of the zenith light is reflected outwards on the outer surface.

The invention, on the other hand, makes it possible to do so directly Fade out sunlight completely as well as a very large proportion of the zenith light through the ceiling in to direct the room, resulting in a correspondingly low luminance contrast between the window opening and the surrounding area Wall

The ceiling of the room is preferably made of aluminum "lit matt surface, so that a considerable, directionally reflected light component results. It is supposed to let the light enter through the window opening Capture as completely as possible and preferably reflect so that the light rays reflected by it with Include a maximum angle of 45 ° with the vertical: This causes glare in normal viewing directions completely avoided. On the basis of this condition, the optimal curvature of the ceiling can be determined calculate or construct. The resulting curved ceiling surface; =: would, however, be different in the usual Extend the depth of the room over a considerable proportion of the height of the room. According to a further development of the Invention is therefore provided to divide this ceiling area into several sections and these sections to be arranged one behind the other at different distances from the window opening. This way is a good one Illumination of a room with a window opening is possible, which - starting from the ceiling - is only extends approximately over 20% of the room height and practically over the entire length of the outer wall.

According to an expedient embodiment of the Ereo ■ the outside of the back of the prisms can be mirrored. The ones that hit these outsides Rays of light are then not refracted again through the prism, but through this playfulness diverted directly into the window opening. «5

In the interest of the highest possible efficiency, the downwardly open acute angle between the outer prismatic lens and the vertical chosen so that the undersides of the individual prisms of the outer Enclose the prism plate with the vertical one at an angle between 80 ° and 100 °: In this case, the largest Part of the zenith light directed directly into the window opening without additional reflection

An exemplary embodiment of the invention is explained in more detail below with reference to the drawing

F i g. 1 a section of a room ceiling and an adjoining outer wall in a schematic representation and

F i g. 2 shows a prismatic lens in an enlarged view.

In Fig. 1 shows a section of an outer wall 1 of a room 2. The outer wall 1 has at its upper one At the end of a window opening 11, which is directly adjacent to the ceiling 4 of the room, which is made of matt aluminum exists, so that there is a diffuse reflection with a directed component

The ceiling has a first inclined surface 44 inclined towards the window opening 11 at a distance a 1 from the outer wall 1, a second inclined surface 45 at a distance a 2 and a further inclined surface 46 at a 3 distance; the associated angles of inclination with respect to the vertical are λ 1, λ 2 and λ 3 and the smaller the greater the distance of an inclined surface from the outer wall 1. Conversely, the size of the vertical projection of each inclined surface increases with its distance from the outer wall 1. In front of each individual inclined surface, the ceiling 4 has a horizontal section 41, 42, 43 and a rear surface 47, 48 between such a horizontal section and the present inclined surface. The angles of inclination of these rear surfaces relative to the vertical are greater than the angles of inclination of the adjacent inclined surfaces. This largely prevents the formation of unfavorable shadows.

In the window opening 11 of the outer wall 1 is how also in FIG. 2, an inner Prisrnenscheibe 6 with a vertically extending, flat outer side -61 and sawtooth. Prisms 62 arranged on the inside. The prisms 62 have a substantially hearing izontal extending upper side 63, which with the obliquely downwardly extending underside 64 an angle of about 35 ° includes. The length of the top 63 and thus the number of prisms in the window opening 11 is chosen so that the tolerances associated with the mass production of the corners and edges on the overall light control have a negligible influence.

In front of the window opening 11, an outer prismatic disk 3 with a flat outside 31 is arranged, the flat outside 31 enclosing an acute angle μ open downwards with the vertical outside 61 of the prismatic sheet 6. On the inside of this outer prismatic pane 3, triangular prisms 32 are arranged in cross section, which run directly next to one another and parallel to one another and parallel to the outer wall 1. They each have a bottom 321, which includes the e ^u enes outside 31 an angle ω, whose size is selected so that light beams with a measured relative to the horizontal Eini case angle β below a limit value / AES ρ of for example 45 ° are totally reflected. This angle ω is calculated using the formula (1)

_ω = 90 ° - {ε \ + ε 2)

where the angles ε 1 and ε 2 are calculated according to the formulas (2) and (3):

sin ε \

(2)

cos ε 2 = ■

(3)

Therein η denotes the refractive index of the material of the prismatic plate and ρ denotes the previously mentioned limit value of the angle of incidence /?.

The angle // between the outer prism plate31 and the vertical is chosen so that the undersides 321 of the prisms 32 are substantially horizontal. The rear sides 322 of the prisms are perpendicular on the underside and are on the inside of the prism mirrored. In this way, totally reflected sun rays are redirected to the outside (Ray 52).

Between the outer end of the outer prismatic lens 3 and the lower edge of the window opening 1 a flat plate 5 with a mirrored top 51 is arranged.

1 shows the course of a beam 5 with the angle of incidence /?: It is first refracted by a prism 32 against the plate 5 and deflected by this into the window opening 11. The beam is refracted several times there by a prism of the inner prism plate 6 and finally enters space 2 at an angle δ of approximately 90 °; the beam then strikes the inclined surface 46 and is reflected by this as beam 5 'with an exit angle ε of less than 45 ° into space. Rays with a smaller angle of incidence may be deflected by the prisms of the outer prismatic pane directly into the window opening 11 without going through the plate 5. At a critical angle ρ , total reflection finally occurs: ray 51 in FIG. 2. If the angle of incidence becomes even smaller, then the totally reflected beam (52 in FIG. 2) is again reflected outwards on the mirrored rear side 322 of the prism 32. By appropriately dimensioning the angles μ, ρ, ω it can be achieved that practically no sun rays enter the room 2 directly.

For this purpose 2 sheets of drawings

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50

60

Claims (1)

Patent claims: 1. Lighting device for illuminating a room with a reflective ceiling (4) with daylight that enters through a window opening (11) in an outer wall (1),
with an outer prismatic disc (3) which is arranged in front of the window opening (11) and has a flat outer side (31) and which forms an acute angle (μ) open at the bottom with the outer wall (1), and
with a flat plate (5) which is designed to be reflective on the upper side and which is arranged between the outer end of the outer prismatic pane (3) remote from the window and the lower edge of the window opening (11),