EP3735103A1 - Light with a coating for de-icing - Google Patents

Abstract

The present invention relates to a lamp with a weather-sensitive elements outwardly covering lamp glass (12), which has means for heating the lamp glass in order to de-ice it, comprising electrically conductive areas that heat up when passing electrical current, wherein according to the invention the electrically Conductive areas comprise at least one conductor track (13) or conductor tracks which are printed onto the lamp glass (12). The application of the means for heating in a printing process is technically less complex than a multiple coating and, for example, does not require work in a high vacuum or under clean room conditions. Another advantage is that comparatively little material is required for the conductor tracks. When energized, the at least one, for example, helically or meandering conductor track is heated and the surface of the lamp glass is effectively de-iced over a large area.

Description

The present invention relates to a luminaire with a luminaire glass which covers weather-sensitive elements towards the outside and which has means for heating the luminaire glass in order to de-ice it.

Luminaires with means for defrosting the luminaire glass have become known from the prior art. Unlike the earlier incandescent lamps, which radiated a not inconsiderable proportion of the energy consumed in the form of heat, modern light sources, such as LEDs in particular, emit comparatively little heat, which is initially intended, since a high degree of efficiency and the highest possible light yield per electrical absorbed Performance to be sought. However, this means that the illuminant no longer heats the cover lens sufficiently, so that a layer of ice deposited on the outside of the cover lens of an outdoor lamp or a headlamp at lower temperatures does not melt or does not melt sufficiently quickly after the lamp is switched on and therefore the layer of ice does not melt the lighting properties impaired, in particular the illuminance of the lamp is reduced.

The DE 10 2008 019 664 A1 describes a headlamp with a cover lens, in which a heating device is provided for defrosting the cover lens, a layer system with several layers being applied to the side of the cover lens facing the interior. This layer system comprises a lower layer, followed by a metal layer and an upper layer. Either the lower layer or the upper layer consists of an oxide or a mixed oxide of one of the elements Si, Ti, Al, Zn, Sn, In, Nb, Zr or Ta or a nitride of the elements Al or Si. A thin metallic layer is applied between the lower and the upper oxide layer, which can be used as a heating element if electricity flows through it. In this way, the cover lens can be de-iced or frost or dew can be avoided. These layers on the cover lens must have sufficient transmission for that of the illuminant Identify emitted light, as otherwise the light yield will be reduced by the layer system. The layer thickness of the lower and the upper layer must therefore be only about 20 nm to 70 nm and the layer thickness of the middle metallic layer consisting of a highly conductive metal such as silver or copper must be even less and is about 5 nm to 20 nm The method of applying several different extremely thin layers one after the other, for example by means of “chemical vapor deposition” (CVD) or “physical vapor deposition” (PVD) in this known solution is relatively complex. If necessary, an additional cover layer has to be deposited on the upper layer, which makes the process even more expensive.

The object of the present invention is to create a lamp with means for heating the lamp glass for the purpose of de-icing with the features of the type mentioned at the beginning, which allows a less complex and thus more economical application of the means for de-icing.

The solution to the aforementioned problem is provided by a lamp with means for heating the lamp glass of the type mentioned at the beginning with the features of claim 1.

According to the invention it is provided that the electrically conductive areas comprise conductor tracks or at least one conductor track that is (is) printed onto the lamp glass.

The application of the means for heating in a printing process is technically less complex than a multiple coating and, for example, does not require work in a high vacuum or under clean room conditions. It is also advantageous that comparatively little material is required for the conductor tracks, since these only extend over a fraction of the total area of the lamp glass to which they are applied. It is sufficient if the conductor tracks are comparatively thin or narrow while a coating is applied over a large area. The printing process is also much more targeted with regard to the surface areas of the luminaire glass intended for the conductor tracks and, unlike when applying a flat coating, practically no coating material is lost. For this reason alone, printing is cheaper.

Another advantage of the method according to the invention is that the printed conductors only extend over a comparatively small area of the printed surface of the lamp glass, so that the light losses are also very low, even if the material that is printed on has a lesser Has transmission than the material of the planar coating according to the prior art.

Although the printed conductor tracks only extend over a very small proportion of the entire light-emitting surface of the lamp glass, the conductor tracks can be arranged on this surface in such a way that a course results through which wide areas of the entire surface of at least one section a conductor path can be run through so that the entire surface of the lamp glass can be heated.

According to a preferred development of the invention, the conductor tracks consist of a highly conductive material, in particular selected from the group comprising ceramic conductive pastes, inorganic conductive pastes, ceramic electrically conductive paint systems, inorganic electrically conductive paint systems, metals, for example silver or copper and metallic alloys. For example, ceramic conductive pastes can be used which contain metal particles such as silver particles or copper particles and a glass frit. By energizing the conductor track, heat is generated, by means of which the surface of the luminaire glass can be heated and thus effectively freed from ice or dew.

When “conductor tracks” are used in the present application, this also includes the case in which only a single conductor track is present. This conductor track can extend from a starting point to an end point on the surface of the lamp glass and follow a path with multiple directional changes. Individual sections of such a single continuous conductor track, each running in one direction, can also be viewed as “conductor tracks” in the context of the present invention.

According to a preferred development of the invention, the conductor track or tracks have a helical course at least in sections. In this preferred variant, the conductor track has sections in one direction and, after reversing the direction, each section which extends approximately in the opposite direction, so that it runs back and forth, so to speak, the reversal of direction running with a radius (arcuate) so that the aforementioned helical course arises. Laying with such an approximately helical course has the advantage that a single conductor track can run continuously over a longer distance without connection points and thereby cover a larger area on the glass surface of the luminaire glass.

According to a preferred development of the invention, at least two contact elements connected to at least one conductor track are printed onto the lamp glass. The conductor path then starts from the first contact point, for example runs approximately helically over the surface of the lamp glass and ends at the second contact point.

According to a preferred development of the invention, at least one conductor track is applied to the surface of the lamp glass with a course such that it runs through the predominant part of the surface of the lamp glass to be heated. The conductor track can, for example, also run in a helical or meandering manner in concentric circles or circular arc segments, in particular when the lamp glass has a round geometry.

According to a preferred further development of the invention, at least one conductor track on the surface of the lamp glass to which it is applied has a meandering course, at least in sections, when viewed from above. Such a meandering course allows, for example, only one conductor track, which runs between two contact points on the surface of the luminaire glass, located in an outer edge area, for example, to run through largely the entire or at least predominant area of the surface with the conductor track. In this way, the possibility is created to heat the surface area of the lamp glass practically over the entire area, but only to cover comparatively small areas of the total area with the material of the conductor tracks. This is different from the application of a flat coating.

A particularly advantageous development of the invention provides that at least one layer of a solder resist is applied to the conductor tracks. This measure serves to protect the printed conductor tracks from corrosion and mechanical damage. Such a solder mask can for example comprise an epoxy resin. Just like the conductor tracks themselves, the solder mask can also be applied, for example, using a screen printing process.

According to a preferred development of the invention, the luminaire is a built-in floor light, in particular a built-in floor light installed outdoors, the heatable light glass of which is a cover glass of the built-in floor light.

According to a development of the invention, the conductor tracks are preferably printed on using the screen printing process. The screen printing process has proven to be particularly suitable to apply the material that is used for printing the conductor tracks to the luminaire glass in a targeted manner in an automated process with numerical control according to a predetermined print pattern. In comparison to conventional coating processes, in which, for example, vapor deposition takes place in a vacuum, the fact that there is little or no loss of coating material is one of the advantages.

According to the present invention, the printed conductor tracks are preferably transparent or largely transparent and / or have a high transmission for the light emitted by the lamp of the lamp, in particular a transmission of at least about 80%, preferably a transmission of at least about 90% preferably a transmission of at least about 95%, particularly preferably a transmission of at least about 98%. The transmission is to be regarded as the ratio of that portion of the light which passes through the cover glass in the area of the printed conductor tracks to the total light emitted by the lamp of the lamp at the corresponding wavelength or wavelengths. In the ideal case, the printed conductor tracks are practically invisible to the naked eye, which is achieved on the one hand by selecting the layer thickness of the printed material of the conductor tracks, which is very small. In addition, the conductor tracks can each be very fine (thin) so that they can hardly be perceived optically due to their small extent in the width direction, which is in the range of approximately one millimeter or preferably less, i.e. only fractions of a millimeter. Even when using very fine conductor tracks, the conductivity is sufficient to ensure sufficient current flow through the conductor tracks, which, due to the electrical resistance of the material of the conductor tracks, leads to heating that heats the luminaire glass to such an extent that it is effectively defrosted and not more fogging.

The solution according to the invention is suitable for all types of lights arranged in the outdoor area, for example recessed floor lights, built-in wall lights, mounted floor lights, mounted wall lights, ceiling lights, street lights, headlights, to name just a few. In principle, the invention can be used for all lights that are exposed to the weather and have a light glass (cover glass) through which the light source emits light. If it is a recessed floor luminaire, it can have, for example, a pot-shaped housing with an approximately cylindrical geometry in principle.

The features mentioned in the subclaims relate to preferred embodiments of the invention. Further advantages of the invention emerge from the following detailed description.

• Figur 1 eine schematisch vereinfachte perspektivische Ansicht einer im Boden eingebauten Leuchte gemäß einer beispielhaften Ausführungsvariante der vorliegenden Erfindung;
• Figur 2 eine Draufsicht auf ein gemäß der Erfindung mit Leiterbahnen bedrucktes Leuchtenglas;
• Figur 3 eine schematisch vereinfachte Schnittansicht durch einen Ausschnitt eines Leuchtenglases im vergrößerten Maßstab.

The present invention is explained in more detail below on the basis of exemplary embodiments with reference to the accompanying drawings. Show:

• Figure 1 a schematically simplified perspective view of a luminaire built into the floor according to an exemplary embodiment of the present invention;
• Figure 2 a plan view of a lamp glass printed according to the invention with conductor tracks;
• Figure 3 a schematically simplified sectional view through a section of a lamp glass on an enlarged scale.

First, the Figure 1 Reference is made and on the basis of this, the basic design of an exemplary recessed floor light according to the present invention is explained. This includes, for example, a cylindrical housing 10, which is sunk into the floor when it is installed. The functional elements such as the illuminant, power supply unit, optical components for directing light, electronic components for controlling the illuminant (s), etc. are located inside the housing 10 and are not explained in more detail here. On the top of the hollow cylindrical housing, an outer flat ring-shaped frame 11 is placed, which is usually fastened by means of screws. This frame 11, which is mostly made of metal, holds the lamp glass 12, which, as a cover glass, covers the housing 10 on the upper face and protects the illuminant and the fixtures from the effects of the weather and mechanically. The light from the lighting means arranged in the interior of the housing 10 is therefore emitted through the lighting glass 12.

According to the present invention, the conductor tracks for heating the lamp glass 12 are attached to its surface, either on the bottom or on the top. These conductor tracks are in the Figure 2 and are explained in more detail below on the basis of this. Figure 2 shows a top view of an exemplary arrangement of a conductor track 13 on the surface of a lamp glass 12. Two contact elements 14 are each arranged in outer edge regions of the lamp glass 12, which are approximately diametrically opposite on the circumference of the approximately circular lamp glass 12. The current for energizing the conductor track 13 can be fed into these two contact elements 14. The contact elements can, for example, also be printed onto the lamp glass.

Starting from the first contact element 14 arranged in the peripheral area, the conductor track initially has a first arcuate section 13 a, which runs concentrically to the outer frame 11 and extends approximately over a quarter circle. Then follows a deflection 13 b by about 180 ° and the conductor track then runs in a further arc segment 13 c in the opposite direction, this second arc segment extending concentrically to the first arcuate section 13 a. This is followed by another deflection 13 d by approximately 180 ° and a third arc segment 13 e follows, which in turn runs concentrically to the second arc segment 13 c. At the end of this arc segment there is again a deflection and a fourth innermost arc segment 13 f then follows, which extends over approximately a semicircle and thus extends to the other side of the surface of the lamp glass 12. The first four concentric arc segments 13 a, 13 c, 13 e, 13 f each run at a distance from one another and cover approximately a quarter of the surface of the approximately circular lamp glass 12. The conductor track 13 thus runs in a meandering manner and in an approximately helical arrangement, the helixes each having an arc-shaped course.

The innermost arc segment 13f extends over a longer distance and virtually establishes the connection to the second quarter of the surface of the lamp glass. At the end of this arc segment 13 f there is again a deflection and the course of the conductor track is then repeated in concentric arc segments, with these being nested inside one another from the inside to the outside. The outermost arc segment 13 g is again made longer and runs over approximately a semicircle in the peripheral area and thus establishes the connection to the third quarter of the surface, so that the arc segments then again run from the outside to the inside and the arrangement described above is repeated in Principle. The outermost arc segment 13h of the fourth quarter of the surface then leads to the second contact element 14, which is diametrically opposite the first contact element. In this way, the entire surface of the lamp glass 12 is largely spanned and covered by the course of only a single continuous conductor track 13 with the concentrically nested quarter-circle or semicircular arc segments between the two contact elements and the entire surface can be heated when the conductor track 13 is energized.

As an alternative to this, an arrangement is also possible, for example, in which the conductor track 13 meanders and helically extends over the surface of the lamp glass, but in rectilinear sections approximately parallel to one another, each with approximately 180 ° deflection between each two sections.

Figure 3 , to which reference is made below, shows a schematically simplified sectional view through a section of a lamp glass on a greatly enlarged scale. The cut is made where a conductor track 13 is located on the lamp glass 12. This conductor track 13 can for example consist of an electrically conductive material such as a ceramic conductive paste which contains a metal such as silver particles or copper particles and a glass frit. In order to protect the conductor track 13 against the effects of the weather and mechanical influences, a layer of a solder resist 15 is applied to the conductor track 13, for example, so that it covers the conductor track.

List of reference symbols

10

casing

11

frame

12

Luminaire glass

13

Track

13 a

arcuate section

13 b

Redirection

13 c

Arc segment

13 d

Redirection

13 e

Arc segment

13 f

Arc segment

13 g

Arc segment

13 h

Arc segment

14th

Contact elements

15th

Solder mask

Claims (11)

Luminaire with a luminaire glass that covers out weather-sensitive elements and has means for heating the luminaire glass in order to de-ice it, comprising electrically conductive areas which heat up when electrical current is passed through, characterized in that the electrically conductive areas have at least one conductor track ( 13) or conductors that are printed on the lamp glass (12). Luminaire according to claim 1, characterized in that the at least one conductor track (13) consists of a highly conductive material, in particular selected from the group comprising ceramic conductive pastes, inorganic conductive pastes, ceramic electrically conductive paint systems, inorganic electrically conductive paint systems, metals, for example silver or Copper and metallic alloys. Luminaire according to Claim 2, characterized in that the at least one conductor track (13) comprises a ceramic conductive paste which contains metal particles, in particular silver particles or copper particles, and a glass frit. Luminaire according to one of Claims 1 to 3, characterized in that the at least one conductor track (13) has a course that is at least partially helical. Luminaire according to one of Claims 1 to 4, characterized in that at least one conductor track (13) is applied to the surface of the lamp glass (12) with such a course that it runs through the predominant part of the surface of the lamp glass to be heated. Luminaire according to one of claims 1 to 5, characterized in that at least one conductor track (13) on the surface of the luminaire glass (12) to which it is applied has a meandering course, at least in sections, when viewed from above. Luminaire according to one of Claims 1 to 6, characterized in that at least two contact elements (14) connected to at least one conductor track (13) or several conductor tracks are applied, in particular printed, to the lamp glass (12). Luminaire according to one of Claims 1 to 7, characterized in that at least one layer of a solder resist (15) is applied to the at least one conductor track (13) or the conductor tracks. Light according to one of Claims 1 to 8, characterized in that it is a built-in floor light, in particular a built-in floor light installed outdoors, the heatable light glass (12) of which is a cover glass of the built-in floor light. Lamp according to one of Claims 1 to 9, characterized in that the conductor track (13) or the conductor tracks are printed on using the screen printing process. Light according to one of Claims 1 to 10, characterized in that the printed conductor (s) (13) are transparent or largely transparent and / or have a high transmission for the light emitted by the lamp of the light.

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