EP1845303B1 - Lamp with plastic reflectors - Google Patents

Description

The invention relates to a lamp having at least partially plastic elements in the form of a reflector or other light-directing element, such as a light-diffusing screen.

The use of plastic elements in lighting construction is not only particularly cost-effective, but also has the advantage that many forms are easy to implement. When using transparent or at least partially transparent plastics In addition, light-directing properties of the luminaire elements can be realized in order to produce special optical effects. However, the plastic elements can also serve as reflectors, for example by a suitable coating.

A major disadvantage, however, have the plastic elements in the luminaire. Under the influence of heat, as generated by the resources of a lamp and by the lamp itself, the plastic elements prove to be non-dimensionally stable. Deformations and distortions can occur especially with elongated elements. These geometric changes not only affect the visual appearance of the luminaire, but also have a negative effect on the lighting effect of the luminaire when the deformed plastic parts are reflectors or other light-directing elements, such as prisms or light-scattering elements.

A plastic light-directing element in the form of a reflector according to the prior art is shown in FIG FIG. 1 shown. The lines represent the shape of the light-directing element at room temperature. Under the influence of a heating by the lamp and the electrical equipment, which are arranged in particular in the middle of the lamp, forms a non-uniform temperature distribution in the light-directing element. This leads to a deformation of the reflector, which in the FIG. 1 is shown overdrawn.

DE 44 16 109 A1 discloses an installation rail with a reflector arrangement for electric bulbs. The reflector elements are inserted in the form of partial reflectors in a side slot of the installation rail. Instead of partial reflectors and translucent shells can be provided. The installation rail is formed from an extruded aluminum profile and carries the electrical equipment.

WO 2005/073629 A1 discloses a directly visible light. The luminaire comprises a housing with several thermally separated chambers for electronic and light-emitting elements. The light exit surface of the luminaire is terminated by an optical device, which can also serve to distribute the heat of the light-emitting elements.

US 2005/0201098 A1 discloses an interior light. A luminaire body of thermally conductive material comprises on the outside of cooling fins and inside LEDs. The light exit surface is closed by a lens which can be inserted on the lamp body.

Object of the present invention is to provide a luminaire of the aforementioned types, which reduces the problem of thermal deformation and warp as much as possible.

The object is achieved by a luminaire with a carrier element, on which at least one heat-generating operating means, such as in particular a ballast, and / or a luminous means of the luminaire is arranged, and at least one light-directing element made of plastic, in particular of a thermoplastic, wherein the carrier element and the light-directing element adjoin one another in a connection region and, during operation of the luminaire, the carrier element and the light-directing element assume different temperatures. The connection region is formed so that a heat flow between the support member and the light-directing element is limited so that the light-directing element outside the connection area assumes a temperature distribution during operation of the lamp, wherein the largest temperature difference is at most .DELTA.T = 10K.

By operation of the luminaire is meant stationary operation, i. at a time after the lamp has been switched on, when the warm-up phase has been completed and all luminaire components have reached their final operating temperature.

The invention is based on the recognition that the thermal deformations and distortions are induced by the fact that the corresponding plastic component is exposed to different temperature ranges. Since the thermal expansion of the plastic depends on the temperature, a temperature gradient has the effect that the corresponding plastic component loses its shape because it expands differently at different locations. In particular, longitudinally extending elements such as lampshades and reflectors of elongated luminaires tend to bend lengthwise.

Due to the special design of the connection region between the support element and the light-directing element made of plastic, such as a reflector or a lampshade, it has been possible to keep the plastic element on a uniform temperature range despite the heating by the resources of the lamp. Although the plastic elements can expand, they retain their shape due to the uniform temperature distribution in the element. This also preserves the optical properties for directing the light.

The inventive reduction of the heat flow between the carrier element and the light-directing element is achieved in that the contact area between the carrier element and the light-directing element is limited to at most 2%, preferably to at most 1% of the surface of the light-directing element. Since the heat flow between two elements is proportional to the size of the contact surface, the heat flow can be reduced in this way. In an alternative embodiment, thermal insulation, for example of a foam material, may also be provided between the carrier element and the light-directing element.

Preferably, the carrier element and the light-directing element are connected to one another via a sliding guide. The sliding guide, as can be used in particular in longitudinally extending lights, has the advantage that the support member and the light-directing plastic element can expand independently and no tension between the two elements occur because the expanding elements in the Sliding guide can shift against each other.

According to one embodiment, the carrier element comprises two projections, in which two complementary receptacles of the light-directing element are inserted in order to connect the carrier element with the light-directing element. The two projections in the carrier element may in particular be two slide rails. By means of the two projections, the light-directing element can be reliably fastened to the carrier element, without the need for a large contact area for connecting the two elements. In particular, the projections and the light directing elements may adjoin one another along narrow contact surfaces, ideally only along one edge. The heat flow, which is transmitted via the contact surface, can thus be reduced to a minimum.

According to a preferred embodiment, at least part of the carrier is in a solid angle region between the luminous means of the luminaire and the light-directing element arranged elements. In particular, that part of the light-directing element is covered by the carrier element, which is closest to the light source. This embodiment has the advantage that the carrier element shields the heat radiation emitted by the light source in the direction of the light-directing element. The space between the carrier element and the light-directing element is in particular dimensioned such that the overlying part of the light-directing element is not heated by thermal radiation from the carrier element. In this way, a strong warming of the lamp closest to the parts of the light-directing element, as formed by thermal radiation of the lamp can be prevented. This embodiment, in addition to the reduction of the heat flow in the components to the fact that the light-directing element of the lamp only evenly, that is heated without a temperature gradient of more than ΔT = 10K.

Can due to geometric conditions, as dictated by the design or the size of the lamp, the height of the gap between the support member and the light-directing element are not sufficiently dimensioned, then in one embodiment of the lamp, the slide rails, which the support member with the light-directing Connect element, be provided with recesses. Through these recesses, air can circulate and provide cooling of the light-directing element.

According to a preferred embodiment, a roof reflector is further attached to the carrier element, which is located between the lamp and the carrier element. The roof reflector in addition to the purely lighting function also has the advantage that it shields the support member from heat radiation of the bulb. In this way, the heating of the support element itself can be reduced. The carrier element may also be formed from plastic, in particular from a thermoplastic.

Preferably, the roof reflector is connected via a sliding guide with the carrier element. Thus, the roof reflector and the support member can expand independently, without causing distortion or distortion of the components.

According to one embodiment, at the contact surfaces between the sliding guides, i. in particular provided on the contact surfaces between the carrier element and the light-directing element, lubricants to assist the movement of the components against each other. Suitable lubricants are especially soft soap, Plexiklar or D96. The lubricants have the special property of being transparent or slightly milky drying and having a poor thermal conductivity. As an alternative or in addition to the use of lubricants, the sliding guide can also be partially interrupted in order to reduce the contact surfaces. By this measure, as well as the lubricants also cracking noises can be prevented, which would otherwise arise during thermal expansion and the associated movement of the components against each other.

According to one embodiment of the luminaire, an at least partially light-transparent luminous cover is furthermore provided on the support element, which defines a closed spatial region together with the support element in a cross section through the luminous means, in which the luminous means is arranged. This illuminant cover has the primary task to achieve a lighting effect, for example, by refractive, light-scattering and / or reflective structures on the Leuchtmittelabdekkung. According to one embodiment of the luminaire according to the invention, the luminous means cover is also connected to the carrier element via a sliding guide, so that these elements can expand independently of one another during heating without causing any distortion. The light-emitting device cover can also be made of plastic, in particular of a thermoplastic. Preferably, the illuminant cover is arranged opposite the illuminant such that it is approximately the same distance (± 20%) to the illuminant cover in a cross-section perpendicular to a longitudinal extent of the illuminant or in spherical geometry of the bulb along all directions. In this way, the heat emitted by heat radiation from the lamp onto the lamp cover heat is emitted evenly to the lamp cover, so that they evenly, ie without a temperature gradient with a temperature difference of more than .DELTA.T = 20K, preferably .DELTA.T = 10K, can heat.

The light directing elements of the invention may have light reflecting and / or refractive structures. In particular, light-refracting structures, in particular line-shaped prism elements, can be arranged on the surface of the light-directing elements. By these structures, for example, a desired shield for the lamp can be generated. The surface of the light-directing elements can also be matt or mirror polished mirrored to act as a reflector of the lamp. Furthermore, the light-directing element can have a light-scattering structure completely or partially in order to change the lighting effect of the luminaire. Details of the refractive structures on the light directing elements and on the illuminant cover are in the German patent application 10 2006 017 255.8 described herein by way of reference.

Figur 1

ist eine perspektivische Ansicht eines lichtlenkenden Elements einer Leuchte aus Kunststoff nach dem Stand der Technik, welche sich bei Erwärmung verformt.

Figur 2

zeigt einen Querschnitt durch einen Teil einer Leuchte gemäß der Erfindung, wobei unterschiedliche Temperaturbereiche dargestellt sind.

Figur 3

zeigt einen Querschnitt durch eine Leuchte der Erfindung.

Figur 4

zeigt einen Querschnitt durch einen Teil einer zweiten Ausführungsform einer Leuchte gemäß der Erfindung.

Figur 5

zeigt einen Querschnitt durch einen Teil einer dritten Ausführungsform einer Leuchte gemäß der Erfindung.

Figur 6

zeigt einen Querschnitt durch einen Teil einer vierten Ausführungsform einer Leuchte der vorliegenden Erfindung.

Further advantages and features of the present invention will become apparent from the following detailed description of a preferred embodiment. The attached figures represent the following:

FIG. 1

is a perspective view of a light-directing element of a plastic light according to the prior art, which deforms when heated.

FIG. 2

shows a cross section through part of a lamp according to the invention, wherein different temperature ranges are shown.

FIG. 3

shows a cross section through a luminaire of the invention.

FIG. 4

shows a cross section through a part of a second embodiment of a lamp according to the invention.

FIG. 5

shows a cross section through a part of a third embodiment of a lamp according to the invention.

FIG. 6

shows a cross section through a part of a fourth embodiment of a luminaire of the present invention.

The embodiments of the invention shown in the figures are lamps which extend in a longitudinal direction and are operated with one or more fluorescent tubes as lighting means. Such lights can be used both as individual lights as well as one behind the other in the form of a light strip. The lights may be mounted either directly on the ceiling or in a preferred embodiment as pendant lights, i. suspended from the ceiling.

The FIGS. 2 to 6 show cross sections in a sectional plane perpendicular to the Längserstrekkung the lamp. There are shown various embodiments of the lamp.

Referring to FIG. 3 a lamp is shown, which generally has the shape of a downwardly opening channel. The light exit opening of the luminaire points downwards. The gutter is essentially composed of three components. In the middle of a symmetrically shaped support member 2 is provided, on which the electrical equipment of the lamp (not shown in the figure) and the lighting means 4 are mounted in the form of a fluorescent tube. The fluorescent tube is connected at the front and the rear end via sockets 5 directly or indirectly (eg via a housing 3) with the carrier element 2.

In addition to the illustrated embodiment with a luminous means, embodiments are also possible in which a plurality of luminous means, for example a plurality of juxtaposed fluorescent tubes, are provided, as shown in FIGS FIGS. 4 and 6 is shown.

The support member 2 may be made of plastic (e.g., a thermoplastic such as PMMA (polymethyl methacrylate) or PC (polycarbonate)) or metal, in particular, an aluminum extrusion or sheet steel.

Above the support element, a two-part housing 3 is mounted in the electrical equipment, such as a ballast, (not shown in the figures) can be accommodated. The operating means may be in thermal contact with the carrier element 2.

On the support member 2 close to both sides of light-deflecting elements 6 made of plastic, which are partially transparent in the illustrated embodiment. As a material, a thermoplastic is provided in this embodiment, which is formed by extrusion. As a plastic material PMMA or PC is particularly suitable.

The light-directing elements 6 are held on the carrier element via a type of sliding guide. For this purpose, two projections 8 and 10 are provided on the carrier element 2 for each of the two light-guiding elements 6, which form a kind of slide rail lengthwise. On the slide rails 8 and 10, the light-directing element 6 is slid lengthwise. For this purpose, two receptacles 12 and 14 are provided on the light-directing element 6, which engage on the projections 8 and 10. The projection 8 abuts against the receptacle 12 on two surfaces. In this case, the receptacle 12 surrounds the projection 8 from two sides. The projection 10 abuts against the receptacle 14 or on the light-directing element 6 likewise at two contact surfaces. In the illustrated embodiment, the projection 10 has two short legs at the end facing the light directing element 6 on. A leg abuts against the receptacle 14 over a narrow area. The second limb bears against the light-directing element 6 only along one edge. In other embodiments, fewer contact surfaces between the projections 8 and 10 and the light-directing element 6 may be provided. In particular, three contact surfaces would suffice for each one light-directing element 6.

Although there are many ways to form the projections and the receptacles, a constructive aspect is very important: Overall, the contact surface must be kept as low as possible. In the embodiment shown, the contact surfaces between the projections 8 and 10 and the receptacles 12 and 14 form an area which is less than 0.5% of the total surface area of the light-directing element 6.

By reducing the contact area as described above, there is an effect that the heat flow from the support member 2 to the light-directing member 6 can be reduced to a minimum. For clarification is on FIG. 2 which shows the heat distribution in the carrier element 2 and the light-directing element 6. In operation of the luminaire, the support member is at a relatively high temperature (between about 65 ° C and 70 ° C), because it is by both the light emitting means 4 and by electrical equipment such as the ballast (not shown), which are arranged thereon is heated. However, the heat flow to the light-directing element 6 is reduced to a minimum due to the small contact surfaces between the projections 8 and 10 and the receptacles 12 and 14. As in the FIG. 2 is shown, the light directing element 6 at least outside the immediate vicinity of the contact surfaces, the so-called connection area, assumes a uniform temperature, which differs across the element by not more than about ΔT = 7K. In the example shown, the temperature is in the range between about 23 ° C and 28 ° C. The connection region extends in the light directing element less than about 2 cm from each side of a contact surface between the support member and the light directing element.

Due to the uniform temperature distribution, in particular in the light-directing element made of plastic, the already described effect is that the plastic element expands only uniformly but no distortion, in particular no bending along its longitudinal extent has. Even if the carrier element 2 expands more strongly in relation to the light-directing element 6, no tension occurs because the elements can move relative to one another along the projections 8 and 10 formed as slide rails and the receptacles 12 and 14, respectively. In one embodiment of the invention, a lubricant is provided in the contact surfaces, such as soft soap, Plexiklar or D96, to assist the movement of the components against each other.

The projections 8 and 14 or the receptacles 10 and 12 are arranged so that a portion 7 of the light-guiding element 6 is shielded by the carrier element 2 from the heat radiation of the luminous means. The partial region 7 is the partial region of the light-directing element which is closest to the light-emitting device 4. This prevents that the portion 7 is heated by heat radiation stronger than the other areas of the light-directing material 6. Thus, the formation of an uneven temperature distribution in the light-directing element 6 is prevented by this measure.

On the support element 2, a roof reflector 16 is also disposed above the light-emitting means 4. The roof reflector 16 primarily serves the purpose of reflecting the light, which is emitted by the lighting means in the direction of the carrier element, in the direction of the light exit opening of the luminaire and / or on the light-directing elements 6. In addition, it also fulfills the task of protecting the carrier element from the heat radiation that is emitted by the lighting device in the direction of the carrier element. As a result, the heating of the carrier element can reduce the operation of the luminaire, in particular in the part which is closest to the luminous means.

The roof reflector 16 is similar to the light-directing elements also held in a sliding guide 18 on the support element. This sliding guide 18 allows that the roof reflector 16 can extend thermally, in particular in the longitudinal direction, independently of the support element 2.

The FIGS. 4 to 6 show alternative embodiments of the lamp, in which case the housing 3 and the sockets 5 are not shown.

The FIG. 4 shows an embodiment, which compared to the embodiment according to FIG. 3 a wider roof reflector 16 'has. In this embodiment, two lamps 4 are further provided. Due to the wider roof reflector 16 ', the carrier element 6 is shielded over almost the entire width. In contrast, in the narrower roof reflector 16, as in FIG. 3 is shown, only a part of the support member 6 shielded. In addition to the roof reflector 16, light can be incident on the carrier element and, for example, in the case of a partially transparent carrier element, it can be emitted to the outside.

The Figures 5 and 6 show two embodiments of the lamp according to the invention, compared to the embodiments according to the Figures 3 and 4 additionally have a bulb cover 20. The illuminant cover 20, which also constitutes a light-directing element, is made of an at least partially transparent plastic. The illuminant cover 20 completely surrounds the illuminant in a cross section perpendicular to the longitudinal extent of the luminous means 4 together with the carrier element 2 or the roof reflector 16 or 16 '. It serves primarily the lighting task to produce a shield to prevent glare from the lamp.

The illuminant cover 20 is hooked into two hooks 22 on the carrier element. For this purpose, an outwardly directed projection 24 of length is respectively provided at the two upper edges of the lamp cover 20, which in the hook 22nd extends. The hooks 22 also extend over the entire length of the light-directing element 6. This connection also acts as a slide, so that the light-emitting device cover 20 can expand independently of the carrier element 2 under the influence of heating by the light source (s) that there is tension or warping between the components. However, the hooks 22 may also be provided with recesses over part of the longitudinal extension of the luminaire.

In the interior of the space enclosed by the illuminant cover and the carrier element, an additional aperture 26 is inserted on the side of the illuminant which faces the light exit surface. The aperture 26 is inserted into two groove-shaped receptacles 28 in the interior of the illuminant cover 20. Also, this connection between the diaphragm 26 and a groove-shaped receptacle 28 acts in the manner of a slide rail to prevent thermal distortion of the two components.

In the aperture 26 may be a high-gloss metal element, which covers the lamp down to glare. But it can also be a partially diffuse reflective material, which also provides a glare.

The illuminant cover 20 is, as in FIG. 5 represented, arranged around the light-emitting means 4, that it occupies approximately the same distance to the light source in the radial direction of the light-emitting means 4. As a result, the heating of the Leuchtmittelabdekkung is evenly distributed over the light source cover by thermal radiation, so that the lamp cover a substantially uniform temperature distribution (.DELTA.T <20K) assumes.

In the illustrated embodiments of the luminaire according to the invention, longitudinally extending prism elements 30 are provided on the light-directing elements 6, which form a triangle in cross-section perpendicular to the longitudinal direction of the luminaire. These worry for a refraction of light, so that a uniform light output of the outgoing light beam from the element 6 light rays is achieved. In other embodiments, the light-directing element may also be formed, for example, as a reflector which is partially or completely mirrored, or as a light-diffusing element which is matt-transparent.

The lamp cover 20 in the embodiments of Figures 5 and 6 have similar prism elements, such as the light-directing elements 6, in order likewise to ensure a refraction of the light transmitted through the illuminant cover.

Numerous changes can be made to the above-described embodiments of the invention without departing from the scope of the invention as defined in the claims. In particular, the invention is not limited to longitudinally extending lights. For example, the features of the invention can also be applied to other geometries, such as round luminaires with spherical or annular bulbs.

LIST OF REFERENCE NUMBERS

2

support element

3

casing

4

Lamp

5

version

6

light directing element

7

Part of the light-directing element

8th

head Start

10

head Start

12

admission

14

admission

16, 16 '

top reflector

18

slide

20

Light cover

22

hook

24

head Start

26

cover

28

groove-shaped recording

30

refractive structures, in particular prismatic elements

Claims (13)

1. Light with a carrier unit (2), at which at least one heat-generating operational unit and/or an illuminant (4) of the light are arranged,
   and at least one light-guiding element (6) made of plastic, in particular from a thermoplastic,
   wherein the carrier unit (2) and the light-guiding element (6) are adjacent to one another in a connecting area (8, 12; 10, 14),
   and, during the operation of the light, the carrier unit (2) and the light-guiding element (6) adopt different temperatures,
   characterized in that the connecting area (8, 12; 10, 14) limits a heat flow between the carrier unit and the light-guiding element to such a degree that, during the operation of the light, the light-guiding element (6) adopts a temperature distribution in which the greatest temperature difference amounts to a maximum of ΔT = 10K, wherein the contact surface between the carrier unit (2) and the light-guiding element (6) amounts to a maximum of 2%.
2. Light according to claim 1, characterized in that the contact surface between the carrier unit (2) and the light-guiding element (6) amounts to a maximum of 1% of the surface of the light-guiding element (6).
3. Light according to any one of the preceding claims, characterized in that the carrier unit (2) and the light-guiding element (6) are connected by a sliding guide.
4. Light according to any one of the preceding claims, characterized in that the carrier unit (2) comprises two projections (8, 10), in particular two sliding rails, which are inserted into two complementary accommodation points (12, 14) of the light-guiding element, in order to connect the carrier unit to the light-guiding element.
5. Light according to any one of the preceding claims, characterized in that at least a part of the carrier unit (2) is arranged in a solid angle region between an illuminant (4) of the light and the light-guiding element (6).
6. Light according to claim 5, characterized in that the said solid angle region covers a part (7) of the light-guiding element (6) which is located closest to the illuminant (4).
7. Light according to any one of the preceding claims, characterized in that a roof reflector (16; 16') is additionally located at the carrier unit, being located between an illuminant (4) of the light and the carrier unit (2).
8. Light according to claim 7, characterized in that the roof reflector (16; 16') is connected by means of a sliding guide (18) to the carrier unit (2).
9. Light according to any one of the preceding claims, characterized in that, additionally, an at least partially light-transparent illuminant cover (20) is located at the carrier unit, which, together with the carrier unit (2), defines a closed spatial area in a cross-section through the illuminant (4), in which the illuminant (4) is arranged.
10. Light according to claim 9, characterized in that the illuminant cover is connected to the carrier unit (2) by means of a sliding guide (22, 24).
11. Light according to any one of the preceding claims, characterized in that the light-guiding element (6) comprises, on at least a part of its surface, light refractive structures (30), in particular linear prism elements.
12. Light according to any one of the preceding claims, characterized in that the light-guiding element (6) is configured to be at least partially light-reflecting.
13. Light according to claim 9 or 10, characterized in that the illuminant cover comprises, on at least a part of its surface, light refractive structures, light diffusing structures, and/or light-reflecting surfaces.

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