Indoor luminaire with lens panel and reflective strips

Abstract

The invention relates to an interior light fixture comprising: at least one light source, in particular one or more LEDs, and reflective strips arranged opposite the light source, which are parallel to each other and define a plurality of light transmission strips with each a defined width (A) between the reflective strips, and a lens plate comprising a plurality of linear lenses with each a defined width perpendicular to the longitudinal extent in the lens plate, corresponding to the plurality of light transmission strips, wherein the lenses are each individually optically assigned to the light transmission strips, and wherein the width of the light transmission strips is each smaller than the width of the assigned lenses.

Description

[0001] The present invention relates to an interior light and in particular to an interior light with optical devices which are designed for glare-free illumination of a workplace.

[0002] For indoor lighting, especially for office lighting, it's challenging to create the most homogeneous appearance possible with good glare control, a small light emission surface, a flat optical design, and a high luminous flux. Important measurable parameters for glare control in office lighting are the Unified Glare Rating (UGR) and the VDU Workstation (VDU) value.

[0003] The UGR is defined in DIN EN 12464-1 and describes direct glare. A low value of less than 19 is considered very good. A poor value can lead to a loss of concentration and thus an increased error rate and fatigue. The value can be influenced by the luminous flux and the lighting surface. A high luminous flux results in a high UGR, i.e., poor glare control. A small lighting surface also results in a high UGR, i.e., poor glare control.

[0004] The BAP value is also described in DIN EN 12464-1 and relates to reflected glare, particularly reflections from screens in the workplace. A low value of 1500 cd / m² above an angle of 65° is a very good value. A value of 3000 cd / m² is also still an acceptable value, as today's TFT screens are significantly less reflective than earlier monitors. However, a value that is too high can also lead to a loss of concentration and thus an increased error rate and fatigue.

[0005] To date, this problem has been solved in various ways. A diffuse plate in the light-emitting surface can be used to create a homogeneous light-emitting surface. However, to meet the required glare values, the luminous flux must be reduced or the light-emitting surface must be enlarged accordingly. Other developments provide a light guide plate, with one side of the plate serving as the light-emitting surface of the luminaire. The light-emitting surface can also be provided with special optical structures, and the side of the light guide plate opposite the light-emitting surface can be provided with reflective material. However, even with these luminaires, the luminous flux must be reduced or the light-emitting surface must be enlarged accordingly to meet the required glare values.

[0006] A special variant of an interior luminaire with improved glare control is described in EP 4 160 084 A1. The interior luminaire comprises a lens plate and a perforated diaphragm. Dome-shaped lenses are integrated into the lens plate, each optically associated with a circular opening in the perforated diaphragm. While this luminaire achieves good glare control values ​​with regard to both direct glare and the reflected glare described above, the luminaire is complex to manufacture because the components must be manufactured in a single piece with high optical precision. Separate molds are required for different luminaire sizes and lengths.

[0007] The object of the present invention is to provide an interior light with good glare control, which is easy to manufacture and, in particular, can also be easily manufactured in different lengths.

[0008] The problem is solved by a luminaire according to claim 1.

[0009] A special feature of the luminaire according to the invention is the type of lens plate and the strip-shaped reflectors below the lens. The lens plate has closely connected linear lenses, which preferably protrude from the lens plate with a curvature only on one side of the lens plate, preferably on the side facing away from the LEDs. The width of the lenses is defined by the spatial extent of the curvature perpendicular to the longitudinal extent of the elongated lenses. The reflective strips are arranged parallel to one another such that they define light transmission strips in the spaces between them, with each light transmission strip being optically assigned to a linear lens in the lens plate. The width of the light transmission strips is each smaller than the width of the lens assigned to it. This limits the maximum beam angles of the light from the lenses, thereby limiting or improving glare.A particular advantage is the shape of the lens plate. Since it only has linear lenses, the cross-section of the lens plate is constant in the direction along the linear lenses. This allows the lens to be easily manufactured using an extrusion process. In contrast to dome-shaped lenses, as described in EP 4 160 084 A1, the lens plate does not have to be manufactured in one piece using a tool in an injection molding process, but can be manufactured virtually endlessly using an extrusion process. Furthermore, the production of the reflector strips is also relatively simple because they can also be manufactured in a straight line along the longitudinal direction of the strips. For example, the reflector strips can be manufactured together with the lens plate in a co-extrusion process. It is also possible to produce the reflector strips separately from the lens plate using an extrusion process.It is also possible to print the reflective strips in a form or to form them from rolled strips, each with a uniform cross-section. These manufacturing processes all allow for continuous formation of the lens plate or reflective strips and can be easily adapted for luminaires of different lengths.

[0010] According to a preferred embodiment, the lenses in the lens plate each define a radius of curvature, and the distance from the center of a light-transmitting strip on a light-entrance side of the lens plate to the vertex corresponding to the respective light-transmitting strip is ±20% of the radius of curvature of the lens. In this configuration, for example, light rays that strike the lens at an angle of 80° to the optical axis are deflected by the convex shape of the lens to approximately 60° to the optical axis. This very effectively limits glare.

[0011] According to a preferred embodiment, the radius of curvature of the lenses in the lens plate is the same for all strip-shaped lenses. This results in a uniform appearance of the light-emitting surface of the luminaire. This is advantageous for office luminaires, as these are easily visible on the light-emitting surface. Furthermore, this embodiment has the advantage of being very easy to manufacture.

[0012] According to a preferred embodiment, the optical axes of the linear lenses extend, in a cross-section perpendicular to the longitudinal extension of the linear lenses, through a center point of the light transmission strip associated with the lens. In this embodiment, the luminaire produces a symmetrical light distribution in the plane perpendicular to the longitudinal extension of the linear lenses. This is advantageous for office applications where a workplace needs to be evenly illuminated.

[0013] According to a preferred embodiment, the ratio between the width (C) of a lens and the width (A) of the light transmission strip associated with the lens is in the range between 1.5 and 2.5, preferably in the range between 1.8 and 2.2. In this embodiment, glare control can be adjusted directly via the ratio of the width of the lens to the width of the light exit strip. However, this also affects system efficiency because a large portion of the light cannot pass directly through the lenses to the light exit side of the luminaire. A ratio of 2 between the width of the light transmission strip and the lens has proven to be particularly good because relatively good glare control can be achieved with comparatively good efficiency.

[0014] According to a preferred embodiment, the lens plate is flat on the sides facing the light transmission strips, at least in the region of the light transmission strips, and the lenses only form a curvature on the side of the lens plate facing away from the light transmission strips. In this embodiment, the flat sections of the lens plate serve as the light entry surface into the lens plate. Due to the flat design, the efficiency of the lens plate is particularly high because the light entry angles into the lens plate are relatively small, so that the proportion of back reflection at the lens plate itself is low. Curved surfaces on the light entry side of the lens plate, in contrast, have the advantage that higher deflection angles at the lens can be achieved due to the surfaces being curved on both sides.

[0015] According to a preferred embodiment, the reflective strips are in contact with the lens plate. For example, the reflective strips can be printed onto the lens plate or glued to it. This allows for a precise optical system to be achieved. In simple embodiments, the lens plate can simply be in contact with the reflective strips without a mechanical connection. These embodiments are particularly cost-effective to manufacture.

[0016] According to a preferred embodiment, the reflective strips are manufactured together with the lens plate using a multi-component extrusion process. In the multi-component extrusion process, a transparent plastic is used to form the lens plate and a light-reflecting plastic is used to form the reflective strips, and these are extruded in a single process step. Since the geometry of both the lens plate and the reflective strip is always constant along its length, such a process can be used, unlike dome-shaped lens plates and perforated plates, which cannot be manufactured in a continuous process.

[0017] According to a preferred embodiment, the reflective strips are each connected to the lens plate by a positive connection, wherein the positive connections each have a continuous cross-section in the direction of the longitudinal extent of the lenses, in particular they are formed by dovetail joints. This embodiment is only possible because the reflective strips in the lens plate have a constant cross-section in a longitudinal extent. The positive connection can be used to subsequently insert the reflective strips lengthwise into the lens plate. In this embodiment, the positive connection comprises geometries which have a constant cross-section in the longitudinal extent of the reflective strips and the lens plate, so that this embodiment can also be manufactured by an extrusion process.

[0018] According to a preferred embodiment, a diffusion plate or diffusion film is arranged between the light source and the reflective strips. This further evens out the incidence of light onto the reflective strips or into the light transmission strips, thereby improving glare control.

[0019] According to a preferred embodiment, a lens with total internal reflection (TIR) ​​is arranged between the light source and the reflective strips, particularly in the previous embodiment between the light source and the diffusion plate or the diffusion film. In this embodiment, the light is redirected directly at the location of the light source so that it falls as evenly as possible on the reflective strips or the light-transmitting strips. This embodiment is particularly suitable for LEDs as light sources because the LEDs form a nearly point-like light source and therefore emit light distributed over an entire half-space.

[0020] According to a preferred embodiment, a reflector is arranged laterally to the light source, in a region between the light source and the reflective strips, particularly in the previous embodiment, in a region laterally to the TIR lens. This reflector is designed to redirect the light from the light source toward the light transmission strips. The reflector serves to redirect the light emitted laterally by the TIR lens or by the light source toward the light transmission strips.

[0021] According to a preferred embodiment, in addition to the aforementioned lens plate and the aforementioned reflective strips, there is a further lens plate and further reflective strips corresponding to the first-mentioned lens plate and the first-mentioned reflective strips, and the further lens plate with the further reflective strips is rotated by 90° to the first-mentioned lens plate and the first-mentioned reflective strips, arranged such that the light from the light source first passes through the first-mentioned light transmission strips, then through the first-mentioned lens plate, then through the further light transmission strips, and finally through the further lens plate. The glare control by means of the reflective strips and the linear lenses of the lens plate essentially only acts in the plane perpendicular to the longitudinal extent of the strips or lenses.By using two arrangements rotated 90° to each other, glare control can be achieved in two perpendicular planes. This results in glare control that is almost as effective as that achieved by using dome-shaped lenses and pinhole diaphragms with circular openings.

[0022] According to a preferred embodiment, a collimator is provided, in particular in the form of an additional reflector and / or additional lenses, wherein the collimator is configured to collimate the light from the light source in a plane that intersects the lens plate perpendicularly and is parallel to the linear lenses. The collimator can be used, in particular, when only one lens plate and one plane of the light transmission strip are used, in order to at least partially also ensure glare control in the plane longitudinal to the strips. The collimator can be formed, for example, by another lens or another reflector.

[0023] According to a preferred embodiment, the reflective strips have a reflectance greater than 80%, in particular greater than 95%, and a transmittance of less than 2%, in particular less than 0.1%. This embodiment increases the efficiency of glare control because less scattered light leaves the luminaire.

[0024] According to a preferred embodiment, the reflective strips have a trapezoidal shape in a cross-section perpendicular to the longitudinal extent, wherein the trapezoidal shape tapers from the lens plate towards the light source. The trapezoidal shape of the reflective strips deflects the light that hits the reflective strips from the side more strongly. In conjunction with the further light guidance in the lens plate, this reduces the angle of light emission, which can further improve glare control. The trapezoids are preferably designed symmetrically. However, asymmetrical shapes can also be useful for special lighting tasks. An asymmetrical trapezoid can be useful for special lighting tasks in which the light output of the luminaire is to be asymmetrically distorted.

[0025] According to a preferred embodiment, the widths of the lenses in the lens plate are at least partially different, and the widths of the light transmission strips are also different, whereby the ratio of the width of the lens to the width of the associated light transmission strip is constant in each case with a maximum deviation of ± 5%. This embodiment is suitable for the formation of a decorative luminaire or for special lighting tasks in which specific light patterns are desired on the surface to be illuminated.

[0026] According to a preferred embodiment, the linear lenses have at least partially a linear freeform surface on one side of the lens plate, in particular for generating a light distribution with two symmetrical maxima in the plane perpendicular to the longitudinal extension of the lenses. Such a light distribution provides very good glare control and can be used, for example, as shelf lighting.

[0027] Further advantages and features of the present invention will become apparent from the following description of preferred embodiments, which is given in conjunction with the accompanying figures. The figures show the following: Figure 1 shows a cross-section through an interior light of a first embodiment. Figure 2 shows a cross-section through the lens plate and the reflective strips of the interior light according to Figure 1 Figure 3 shows a perspective view of the lens plate with the reflective strips of the interior light according to Figure 1 on the light exit side. Figure 4 shows a perspective view of the lens plate and the reflective strips of the interior light after Figure 1from the side facing the light source. Figure 5 shows a cross section through a lens plate with reflective stripes according to an alternative embodiment. Figure 6 shows a perspective view of the lens plate and the reflective stripes of the Figure 5 on the light exit side. Figure 7 shows a perspective view of the lens plate and the reflective strips of the Figure 5 from the side facing the light source. Figure 8 shows an enlarged cross-section through the lens plate with the reflective stripes according to Figure 1 with an incident beam of rays. Figure 9 shows a view corresponding to the Figure 8, but with a beam of rays that has a larger angle of incidence to the optical axis. Figure 10 shows an enlarged cross-section through a lens plate with reflective stripes according to an alternative embodiment with a trapezoidal cross-section. Figure 11 shows an enlarged cross-section through a lens plate with trapezoidal reflective stripes and a dovetail connection between the reflective stripes and the lens plate. Figure 12 shows a cross-section through a lens plate with linear freeform lenses and reflective stripes. The pictogram shows light distributions of the embodiment. Figure 13 shows a perspective view of two lens plates, each with reflective stripes, from the side facing the light source.

[0028] The Figure 1shows a cross-sectional view of the structure of an interior light according to a first embodiment. The cross-section shown shows the light perpendicular to the longitudinal extension, which runs perpendicular to the image plane and is constant in cross-section.

[0029] The light source is an LED 1, which is arranged on an LED circuit board 2. The circuit board 2 is enclosed by a highly reflective reflector 4. The reflector 4 is located in a lamp housing 3. For better homogenization of the lamp's rays, the rays are redirected to both sides of the reflector 4 via a TIR lens 5. From the reflector 4, the light goes towards a lens plate 8, on which reflective strips 7 are attached. In addition, in the embodiment shown, a diffusion plate 6, which can also be designed as a film, is mounted on the side facing the light source 1. This ensures additional homogenization of the light that hits the lens plate 8 with the reflective strips 7.

[0030] The Figure 2shows the lens plate 8 and the reflective strips 7 in cross section. Furthermore, an optical axis 9 of the linear lenses is shown. However, since the lenses have a continuous cross section perpendicular to the image plane of the Figure 2 the optical axis 9 is also in each case to the image plane of the Figure 2parallel plane. Furthermore, the spacing of the reflective strips 7 is designated by A, the width of the reflective strips by B, and the width of the linear lenses by C. In the embodiment shown, the values ​​for A, B, and C are the same for all strips 7 and lenses 8. The areas A between the reflective strips 7 form light transmission strips with a width A, through which the light passes and penetrates the lens plate. According to the invention, the width A for each light transmission strip is smaller than the width C of the associated lens. As a result, the light transmission through the lens is limited to width A, which, in conjunction with the optical effect of the lens, makes it possible to reduce glare in the luminaire.

[0031] The Figure 3 shows the optical system Figure 2in a three-dimensional representation with a view of the light-emitting surface of the luminaire, ie the side of the lens plate on which the linear lenses protrude with a curvature.

[0032] The Figure 4 shows the optical system Figure 2 in a three-dimensional representation with the view of the light entry surface of the lens plate, ie the side of the lens plate on which reflective strips 7 are arranged.

[0033] The Figure 8 shows a beam path through the optical system. A light beam that, as in Figure 8Light entering the lens plate at an angle of approximately 25° to the optical axis 9 exits the lens plate at an angle of approximately 18°. Light rays reflected laterally by the reflective strips also exit the lens plate at a smaller angle. This can significantly reduce glare. Light reflected back into the luminaire structure on the side of the strips facing the light source 1 can be redirected by the reflector 4 toward the lens plate until these rays also exit the lens plate.

[0034] In Figure 9 Light rays are shown that strike the lens plate 8 or the reflective strips 7 at an angle of approximately 60° to the optical axis 9. These leave the lens plate at an angle of approximately 44°.

[0035] In the Figure 5 an alternative embodiment is shown in which the reflective strips 7 have the shape of a trapezoid in cross section.

[0036] The Figures 6 and 7 represent the optical system Figure 5 in the three-dimensional representation on the light entry surface or on the light exit surface of the lens plate. The beam path is in Figure 11 to see. Glare can be further reduced thanks to the trapezoidal shape. The trapezoidal shape, which tapers in the direction from the lens plate to the light source, increases the deflection angle of the incoming light rays. The light rays therefore enter the lens plate at a smaller angle to the optical axis 9 and are accordingly deflected further toward the optical axis 9 by the lens plate.

[0037] The reflective strips can be, as in the Figures 1 to 4 and 8 to 10As shown, they lie flat against the lens plate 8. The strips can be attached to the lens plate, for example, by gluing. However, it is preferred that the reflective strips be manufactured together with the lens plate using a co-extrusion process. In further embodiments, however, it can also be provided that the reflective strips are arranged at a distance from the lens plate in the luminaire.

[0038] The embodiments of the Figures 5, 6 , 7 and 11 to 13show a further variant in which the reflective strips are connected to the lens plate 8 by a positive connection. For this purpose, the reflective strips 7 have a projection on the side facing the lens plate, which engages positively with a recess in the lens plate 8. In the embodiment shown, the projection is dovetail-shaped. However, other cross-sectional shapes are also possible. In these embodiments, the reflective strip 7 can be manufactured together with the lens plate 8 in a co-extrusion process. However, it is possible to manufacture the strips separately from the lens plate and to connect them to it by pushing the elongated projections of the lens strips 7 into the elongated recesses of the lens plate 8.

[0039] In all versions of the Figures 1 to 11The linear lenses have a radius of curvature L in a cross-section perpendicular to their longitudinal extension. The radius of curvature L is in the Figure 8 According to the preferred embodiments, the radius of curvature L is approximately equal to the distance between the light entrance side of the lens plate 8 and the vertex of the lens on the light exit side. This distance can also be L ± 20%.

[0040] The Figure 12 In contrast, Fig. 8 shows a lens plate 8 in which the lenses have no radius, but are designed as a free-form surface on the light exit side. This allows, for example, a light distribution curve to be generated, as shown in the pictogram of the Figure 12The light distribution exhibits two distinct symmetrical maxima in a Co-180 plane (in the example shown, at ± 30°). The Co-180 plane corresponds to the plane of the luminaire, which runs perpendicular to the lens plate and perpendicular to the longitudinal extension of the lenses 8 and the strips 7, respectively.

[0041] The Figure 13shows a further embodiment in which two lens plates 8, each with reflective strips 7, are provided. The lens plates 8, with their respective reflective strips 7, are arranged parallel to one another and rotated by an angle of 90° to one another. A single lens plate with reflective strips creates glare control in a C-plane, which runs perpendicular to the longitudinal extent of the lenses. By combining two lens plates rotated by 90° to one another, the luminaire can therefore achieve glare control in both C-planes (e.g., in the C-0-180 and the C-90-270 planes).

[0042] Numerous variations of the embodiments shown in the figures are possible within the scope of the invention. For example, to reduce glare in two mutually perpendicular C-planes, instead of the embodiment according to Figure 13A collimator may also be provided within the luminaire, which collimates the light from the light source in a plane approximately perpendicular to the longitudinal extension of the lenses or strips. For example, the collimator can be formed by a corresponding device consisting of reflectors or lenses instead of or in combination with the TIR lens 7 or the reflector 4. List of reference symbols

[0043] 1Light source, especially LED 2LED board 3Luminaire housing 4Reflector 5TIR lens 6Diffuser plate or film 7Reflective strips 8Lens in a lens plate 9Optical axis AWidth of a light transmission strip BBidth of a reflective strip CWidth of a lens in the lens plate

Claims

1. Interior light, comprising: at least one light source (1), in particular one or more LEDs, and reflective strips (7) arranged opposite the light source (1), which are parallel to one another and define a plurality of light transmission strips, each with a defined width (A), between the reflective strips (7), and a lens plate which has a plurality of linear lenses (8) corresponding to the plurality of light transmission strips, each with a defined width (B) perpendicular to the longitudinal extent in the lens plate, wherein the lenses (8) are each individually optically assigned to the light transmission strips, and wherein the width (A) of the light transmission strips is in each case smaller than the width (C) of the assigned lenses (8).

2. Interior light according to claim 1, wherein the lenses (8) in the lens plate each define a radius of curvature and the distance from the center of a light passage strip on a light entry side of the lens plate to the apex of the lens (8) assigned to the respective light passage strip corresponds to the radius of curvature (L) of the lens (8) ±20%.

3. Interior light according to claim 2, wherein the radius of curvature (L) of the lenses (8) in the lens plate is the same for all strip-shaped lenses (8).

4. Interior light according to one of the preceding claims, wherein optical axes (9) of the linear lenses (8) in a cross section perpendicular to the longitudinal extent of the linear lenses (8) each extend through a center point of the light transmission strip associated with the lens (8).

5. Interior light according to one of the preceding claims, the ratio between the width (C) of a lens (8) and the width (A) of the light transmission strip associated with the lens (8) is in the range between 1.5 and 2.5, preferably in the range between 1.8 and 2.

2.

6. Interior light according to one of the preceding claims, wherein the lens plate is flat on the side facing the light passage strips at least in the region of the light passage strips and the lenses (8) form a curvature only on the side of the lens plate facing away from the light passage strips.

7. Interior light according to one of the preceding claims, wherein the reflective strips (7) rest against the lens plate.

8. Interior light according to one of the preceding claims, wherein the reflective strips (7) are manufactured together with the lens plate by multi-component injection molding.

9. Interior light according to one of claims 1 to 7, wherein the reflective strips (7) are each connected to the lens plate by a positive connection, wherein the positive connections each have a continuous cross-section in the direction of the longitudinal extent of the lenses (8), in particular are formed by dovetail connections.

10. Interior light according to one of the preceding claims, wherein a diffusing plate or diffusing film (6) is arranged between the light source (1) and the reflective strips (7).

11. Interior light according to one of the preceding claims, wherein a lens with total internal reflection, TIR lens, (5) is arranged between the light source (1) and the reflective strips (7), in particular when referring back to claim 10 between the light source (1) and the diffusion plate or the diffusion film (6).

12. Interior light according to one of the preceding claims, wherein a reflector (4) is arranged laterally to the light source (1), in a region between the light source (1) and the reflective strips (7), in particular when referring back to claim 11 in a region laterally to the TIR lens (5), which reflector is designed to redirect the light of the light source (1) in the direction of the light transmission strips.

13. Interior light according to one of the preceding claims, wherein in addition to said lens plate and said reflective strips (7), there is a further lens plate and further reflective strips (7) corresponding to the first-mentioned lens plate and the first-mentioned reflective strips (7), and the further lens plate with the further reflective strips (7) are arranged rotated by 90° to the first-mentioned lens plate and the first-mentioned reflective strips (7) such that the light from the light source (1) first passes through the first-mentioned light transmission strips, then through the first-mentioned lens plate, then through the further light transmission strips and finally through the further lens plate.

14. Interior light according to one of the preceding claims, wherein a collimator, in particular in the form of an additional reflector and / or additional lenses, is provided, wherein the collimator is designed to collimate the light of the light source (1) in a plane which intersects the lens plate perpendicularly and lies parallel to the linear lenses.

15. Interior light according to one of the preceding claims, wherein the reflective strips (7) have a reflectance greater than 80%, in particular greater than 95%, and a transmission of less than 2%, in particular less than 0.1%.

16. Interior light according to one of the preceding claims, wherein the reflective strips (7) have a trapezoidal shape in a cross-section perpendicular to the longitudinal extent, the trapezoidal shape tapering from the lens plate towards the light source (1).

17. Interior light according to one of the preceding claims, wherein the widths (C) of the lenses (8) in the lens plate are at least partially different and the widths (A) of the light transmission strips are also different, wherein the ratio of the width (C) of the lens (8) to the width (A) of the light transmission strip associated with it is in each case constant with a maximum deviation of ± 5%.

18. Interior light according to one of the preceding claims, wherein the linear lenses (8) on one side of the lens plate at least partially have a linear free-form surface, in particular for generating a light distribution with two symmetrical maxima in the plane perpendicular to the longitudinal extent of the lenses (8).

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