KR20090031695A - Discharge lamp, particularly low-pressure discharge lamp - Google Patents

Abstract

The invention relates to a discharge lamp, particularly a low-pressure discharge lamp, comprising a discharge vessel (2), two electrodes (3, 4) that are disposed at least in part inside the discharge vessel (2), and a first coating (9) which is arranged at least in some areas of an external face (23) of the discharge vessel (2) and is made of a first material. A second coating (10a, 10b) made of a second material is placed on the external face (23) of the discharge vessel (2), in the area (24, 25) of at least one electrode (3, 4).

Description

Discharge lamps, especially low-pressure discharge lamps {DISCHARGE LAMP, PARTICULARLY LOW­PRESSURE DISCHARGE LAMP}

The present invention relates to a discharge lamp, in particular a low voltage discharge lamp, having a discharge tube and two electrodes at least partially disposed within the discharge tube and a first coating at least locally disposed on an outer surface of the discharge tube and made of a first material.

1 schematically shows a low pressure discharge lamp known in the art. The low-pressure discharge lamp formed as a fluorescent lamp 1 includes a tubular discharge tube 2, and electrodes 3 or 4 are disposed in the end regions 21 and 22 of the discharge tube 2 facing each other, respectively, and the light base It is fixed at (5 or 6). Contact pins 7a, 7b and 8a and 8b respectively extend outwards. In fact, a coating 9 spanning the length of the fluorescent lamp 1 is provided on the outer surface 23 of the discharge vessel 2. The coating 9 is formed of a plastic coating. The plastic layer has substantially the same thickness and the same outer diameter over the entire length (y-direction). In the case of fluorescent lamps 1 known in the prior art, there arises a problem that sufficient thermal stability and sufficient UV (ultraviolet) stability for most plastics are given only to relatively low load fluorescent lamps 1. Therefore, such stability is generally provided only in fluorescent lamp 1 having a discharge current of less than 200 mA. For lamps with larger discharge currents and high loads, the requirements for such coatings are no longer met.

It is an object of the present invention to provide a discharge lamp with an outer coating having sufficient thermal stability even for a discharge lamp under relatively high load.

This object is achieved by a discharge lamp having the features of claim 1.

The discharge lamp according to the invention is formed in particular as a low pressure discharge lamp. The discharge lamp includes a discharge tube and first and second electrodes at least partially disposed within the discharge tube. On the outer surface of the discharge vessel, a first coating formed of a first material is at least locally disposed. In the region of the at least one electrode a second coating made of a second material is arranged on the outer surface of the discharge vessel. By providing various coatings depending on the place on the outer surface of the discharge tube, an outer coating having sufficient functionality can be obtained even for a relatively high load discharge lamp, because of the arrangement of the coatings and / or the material properties of the coatings. . Thereby, markedly improved functionality can be achieved, especially for discharge lamps with discharge currents above 200 mA, in particular with discharge currents above 300 mA. In addition, such external coatings can be optionally colored or colored.

In a preferred manner, a second coating is formed on the outer surface of the discharge tube in the region of the first electrode and the region of the second electrode, respectively. In particular if the two electrodes are relatively overheated during operation, and for that reason the area of the discharge vessel adjacent to the electrode is exposed to elevated temperature loads and elevated ultraviolet radiation, in that case the second coating is locally placed on both sides as above. This can provide a sufficient multilayer arrangement for fundamental functionality. The second coating, which is provided only in critical areas, allows the optimum functionality of the layer structure to be achieved while at the same time relatively low cost and material savings can be realized.

The second coating is preferably disposed directly on the outer surface of the discharge vessel, and the first coating is formed on the second coating. The first coating can then at least locally cover or completely cover the second coating. When fully covered, the second coating is in contact only with the outer surface of the discharge vessel on one side and with the first coating on the other. In this embodiment the second coating is completely surrounded by these two components, ie by the first coating and the outer surface of the discharge vessel. In addition to at least local contacting of the second and first coatings, in particular with full surface contacting, the second coating can also be arranged to be fixed at least locally directly to the outer surface of the discharge vessel. However, even in this case, the side of the second coating facing the discharge tube may be adjacent to the outer surface of the discharge tube with its entire surface. Thus, depending on the shape of the discharge vessel and / or the shape of the second coating, an optimum arrangement can be achieved in a flexible manner as needed and in connection with the desired functionality.

The first coating is arranged outside of the second coating, preferably on the outer surface of the discharge vessel. In this case too, the first coating can be installed at least partially directly. In particular in the case where two or more second coatings are provided, the two second coatings are each formed as separate coatings and are positioned separately from each other. By placing the first coating directly on the outer surface of the discharge vessel, the first coating can also serve as a separating element that separates between the two second coatings. In particular, the first coating and the second coating are arranged such that in areas where the two coatings overlap, the resulting layer system is formed thicker than in areas where only one coating is present. In particular, a thicker layer structure can be formed on the outer surface of the discharge tube in the region of at least one electrode than in the region separated from the outer surface of the discharge tube. Thus, not only temperature stability but also ultraviolet stability can be optimally achieved as necessary in almost all areas where the discharge tube is on the outer surface. Preferably the materials of the two coatings are different. Plastic coatings may preferably be provided for the first coating. In this case, for example, materials such as VPE (crosslinked polyethylene), PET (polyethylene terephthalate), PC (polycarbonate) may be provided. Such explicit enumeration of plastics is merely an example, and other plastics may also be included.

As the material of the second coating, a glass material or a ceramic may be used. Plastic materials may also be provided. For example, the plastic materials may be HDPE (overdense polyethylene), POCAN, silicon (Silicone), FEP (perfluoro (ethylene-propylene) plastic), PTEE (polytetrafluoroethylene) or PC (polycarbonate). The explicit enumeration of such plastic materials should not be considered decisive, but is only an example.

The first coating and the second coating may be composed of the same material. Functionality associated with sufficient thermal stability and sufficient ultraviolet stability, for example, can be achieved through thickness changes in specified areas on the outer surface of the discharge vessel.

In addition to the typical materials described above for the first and second coatings, a combination of materials may also be provided, respectively.

Preferably the first coating extends over the entire outer surface of the discharge vessel.

Preferably the materials of the first coating are formed for functional use in connection with fission protection and / or as spectral filters. The second coating may be formed of a material that allows sufficient function as the spectral filter. Particularly in connection with the spectral filter function, the materials can be formed to enable the manufacture of discharge lamps having light colors filled with, for example, red, green, blue and yellow. Sufficient ultraviolet protection can also be advantageously met by the coatings.

As a result, discharge lamps are provided that can be used in various fields of use. Thus, such discharge lamps can be used as a light source, for example, in the effect lighting of a lighting device with adaptive color. Discharge lamps with fission protection and UV protection have meaning for companies producing food products and, for example, associated with the packaging of such food products. Discharge lamps with suitable spectral filter functions can also be used in lithographic techniques in chip manufacturing.

Preferably the materials of the two coatings are formed such that the material of the second coating has a higher temperature stability than the material of the first coating. The temperature stability or thermal stability of a material means, among other things, that the materials retain their elastic properties, do not depolymerize, oxidize, and also have brittleness under the influence of relatively high temperatures. will be.

Preferably the second coating has a thickness or expansion of less than 10 mm, in particular less than 6 mm, preferably in particular of 0.5 mm to 5 mm, from the discharge vessel surface to the surface opposite the discharge vessel. The thickness of the second coating can vary as well as the thickness of the first coating.

The second coating consists of a layer system and may even comprise at least two coatings by itself. Likewise the face of the first coating on the opposite side of the outer face of the discharge vessel can be at least locally covered with a further third layer. The first coating and in some cases the second coating can equally be composed of a multilayer system.

Preferably, the discharge vessel is formed in a tubular shape, and two electrodes are disposed at opposite ends of the discharge vessel. The electrodes can be formed substantially identical in size and shape. However, the electrodes may have different sizes and shapes. Preferably, not only the first coating but also the second coating is completely enclosed in the radial direction when the discharge tube is formed in a tubular shape. This can in particular provide a fluorescent lamp with an optimal layer system.

Embodiments of the present invention are described in detail below with reference to the schematic drawings.

1 is a cross-sectional view of a fluorescent lamp known in the prior art.

2 is a schematic cross-sectional view of a discharge lamp according to the present invention.

2 shows a cross-sectional view of a low voltage discharge lamp formed as a fluorescent lamp 1 'in a schematic manner. The fluorescent lamp 1 'comprises a tubular discharge tube 2, for example, this tubular discharge tube 2 may be a flask. The electrodes 3 and 4 are respectively disposed in the end regions 21 and 22 facing the discharge tube 2 and fixed to the corresponding lamp bases 5 and 6. Two electrical contact pins 7a, 7b and 8a and 8b extend outwardly from the light bases 5 and 6, respectively. The second coating 10a is formed on the outer surface 23 of the discharge tube 2 in the region 24 of the first electrode 3. The second coating 10a is completely enclosed in the radial direction of the discharge tube 2 and is therefore arranged in an annular shape on the outer surface 23. As can be seen from the figure, the second coating 10a is in direct contact with the outer surface 23 with the entire surface of the surface of the second coating facing the outer surface 23. In the cross section shown, the second coating 10a has a hilly structure. This is merely an example and may be formed in various other ways and shapes. In an embodiment the second coating 10a is about twice the distance of the electrode-light base at the outer surface 23 from the side of the light base 5 which actually faces the discharge vessel 2 in the longitudinal direction (y-direction). Extends to. The length extension of the second direction 10a is merely an example, and may be formed in other ways. In this case, the second coating 10a may have a shape that extends further in the longitudinal direction or extends shorter in the center direction of the discharge tube 2. The second coating 10a has a variable thickness (z-direction) over its length extension (y-direction) by its hill-shaped cross section.

On the side facing the light base 5, the second coating 10a can be formed for example up to the outer end of the light base 5.

In a similar manner additional second coating 10b is likewise formed in region 25. Thus, in the embodiment, separate second coatings 10a or 10b are respectively provided on the outer surface 23 of the discharge vessel 2 in the regions 24 and 25 and thus in the two regions of the electrodes 3 and 4. The two second coatings 10a and 10b are arranged separated from each other and are formed without contact with each other. The arrangement, shape and material design of the additional second coating 10b is formed similarly to the opposing second coating 10a.

In the embodiment, the second electrode 4 is formed in the same manner as the first electrode 3 and is fixed to the end region 22 of the discharge tube 2 using the light base 6.

The two second coatings 10a and 10b have an extension of about 20 mm in the longitudinal direction and thus in the y-direction. These figures are just examples too, and can be larger or smaller.

In addition, the first coating 9 is arranged such that the coating completely covers the two second coatings 10a and 10b on the empty surface. As can be seen from the figure, the first coating 9 extends over the entire length of the discharge vessel 2 and the light bases 5 and 6 connecting to the discharge vessel. The first coating 9 may only extend over the entire length of the discharge vessel 2. The first coating 9 may likewise be formed to extend to and directly adjacent to the rear walls 51 and 61 of the light bases 5 and 6, based on the illustration of FIG. 2.

As further shown in FIG. 2, the first coating 9 is disposed directly on the outer surface 23 of the discharge vessel 2 at the center of the discharge 2 and between the second coatings 10a and 10b.

The first coating 9 is likewise arranged completely enclosed in the radial direction of the discharge tube 2.

The first coating 9 has a substantially constant layer thickness (z-direction) over its full length extension.

In the embodiment, the arrangement of the first coating 9 and the second coatings 10a and 10b results in a local layer system formed of different thicknesses. In this way, the function of the discharge lamp 1 'can be made the best. In particular, in areas 24 and 25 where elevated flask temperatures and elevated ultraviolet radiation are exhibited due to the operation of the discharge lamp 1 ', the first coating 9 is not in direct contact with the outer surface 23, the outer surface 23 Are installed at predetermined intervals. In this regard the second coatings 10a and 10b serve as spacers.

The materials of the second coatings 10a and 10b are selected to have higher thermal stability than the materials of the first coating 9.

In addition, the second coatings 10a and 10b are formed in their intermediate region to a thickness greater than the thickness of the first coating 9.

The first coating 9 is formed of a plastic coating.

The second coatings 10a and 10b may be made of the materials described above in consideration of the functions required for the fluorescent lamp 1 '. In the combination of coatings 9, 10a and 10b materials, the optimization can also be made in relation to the requirements of the discharge lamp or the fluorescent lamp 1 'in the shape and arrangement of the coatings.

In addition, the second coatings 10a and 10b may be composed of multiple partial layers. At least one air layer may be formed in the second coatings 10a and 10b. The air layer can also be formed between the first coating 9 and the second coating 10a or 10b.

On the side of the first coating 9, which faces the outer surface 23 of the discharge vessel 2, an additional third layer can be provided at least locally. For example, such an additional third layer may be provided in the region between the two coatings 10a and 10b on the first coating 9. In this way flattening of one surface of the outwardly facing first coating 9 can be achieved. However, the first coating 9 can also be formed to such a thickness that the outer surface of the first coating 9 is formed flat over the entire length in the region between the second coatings 10a and 10b.

The first material of the first coating 9 as well as the second material of the second coatings 10a and 10b have the property that each of the coatings can be used as a break protection and / or as a spectral filter. In addition, the selected materials ensure sufficient thermal stability and sufficient ultraviolet stability in the fluorescent lamp 1 'with a discharge current exceeding 300 mA.

Thus, in the illustrated embodiment, the second coatings 10a and 10b are arranged on both sides in the region of the end regions 21 and 22 of the discharge vessel 2.

A further important advantage of the discharge lamp 1 'according to the invention is that the manufacture and production of the discharge lamp 1' can be made relatively simple. Through the use or provision of a second coating, the first coating can be coated, for example in the form of a shrink tube or in a working process using extrusion.

Claims (17)

A first coating made of a first material and at least locally disposed on the discharge tube 2 and the two electrodes 3, 4 at least partially disposed within the discharge tube 2 and the outer surface 23 of the discharge tube 2 ( In discharge lamps, in particular low-pressure discharge lamps, In the regions 24, 25 of the at least one electrode 3, 4, a second coating 10a, 10b made of a second material is arranged on the outer surface 23 of the discharge tube 2. lamp. The method of claim 1, In the regions 24 and 25 of the first electrodes 3 and 4 and the regions 24 and 25 of the second electrodes 3 and 4, the second coatings 10a and 10b are formed on the outer surface of the discharge tube 2, respectively. 23, characterized in that the discharge lamp. The method according to claim 1 or 2, Discharge lamp, characterized in that the second coating (10a, 10b) is arranged directly on the outer surface (23) of the discharge vessel (2), the first coating (9) is formed in accordance with the second coating (10a, 10b). The method according to any one of claims 1 to 3, Discharge lamp, characterized in that the first coating (9) at least locally covers the second coating (10a, 10b). The method according to any one of claims 1 to 4, Discharge lamp, characterized in that the second coating (10a, 10b) is at least locally disposed directly on the outer surface (23) of the discharge vessel (2). The method according to any one of claims 1 to 5, Discharge lamp, characterized in that the first coating (9) is arranged directly on the outer surface (23) of the discharge tube (2) outside the second coating (10a, 10b). The method according to any one of claims 1 to 6, Discharge lamp, characterized in that in an area (24, 25) where two coatings (9, 10a, 10b) are superimposed, the coating arrangement is formed thicker than in an area where only one coating (9) is present. The method according to any one of claims 1 to 7, Discharge lamp, characterized in that the materials of the two coatings (9, 10a, 10b) are different. The method according to any one of claims 1 to 8, Discharge lamp, characterized in that the first coating (9) extends over the entire length of the outer surface (23) of the discharge vessel (2). The method according to any one of claims 1 to 9, Discharge lamp, characterized in that the coating (9, 10a, 10b) has a temperature stability and ultraviolet stability. The method according to any one of claims 1 to 10, Discharge lamp, characterized in that the material of the coating (9, 10a, 10b) is formed such that the coating (9, 10a, 10b) can be used as a break protection and / or as a spectral filter. The method according to any one of claims 1 to 11, Discharge lamp, characterized in that the first coating (9) is formed of plastic, in particular VPE or PET or PC. The method according to any one of claims 1 to 12, Discharge lamp, characterized in that the second coating (10a, 10b) is formed of a glass material or glass-like material or a ceramic or plastic The method according to any one of claims 1 to 13, Discharge lamp, characterized in that the second coating (10a, 10b) has a higher temperature stability than the material of the first coating (9). The method according to any one of claims 1 to 14, Discharge lamp, characterized in that the second coating (10a, 10b) has a thickness of less than 10 mm, in particular less than 6 mm, in particular from 0.5 mm to 5 mm. The method according to any one of claims 1 to 15, A discharge lamp, characterized in that the electrodes (3, 4) are arranged in opposite end regions (21, 22) of the discharge vessel (2). The method according to any one of claims 1 to 16, The discharge tube 2 is formed in a tubular shape, and two second coatings 10a and 10b completely surrounding the discharge tube 2 are respectively provided at the end regions 21 and 22 facing each other of the discharge tube 2. And the two second coatings are completely covered by a first coating (9), the first coating on the outer surface (23) of the discharge vessel (2) between the two second coatings (10a, 10b). Discharge lamp, characterized in that arranged directly.

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