FIELD OF THE INVENTION

The invention relates to a luminescent lamp for lighting birds, particularly poultry. The invention also relates to a poultry farmhouse with interior lighting comprising one or more of such luminescent lamps. The invention also relates to the use of such luminescent lamp in a poultry farmhouse. Furthermore, the invention relates to a method of bird farming, including lighting birds during a predetermined period of time, the lighting being performed with one or more of such luminescent lamps.

BACKGROUND OF THE INVENTION Poultry farming (or poultry husbandry) is a growing branch in the production of meat, eggs and feathers. Commercial factors promote poultry farming in large poultry farms.

In such farms, lighting is also important because it may influence production and/or the birds' well-being. US 4,625,728 describes a method of improving egg production by irradiating poultry with energy levels, the first of which is within a wavelength band of 600 to 670 nm and is supplied at a rate of at least 1013 quanta/second/cm ² , and, if this first radiation is less than 1013 quanta/second/cm ² , at least 75% of the total supply of energy is within the first wavelength band. The second radiation energy level is within a wavelength band of 400 to 600 nm and is supplied at a rate of at least 1014 quanta/second/cm ² , and, if this second radiation is less than 1014 quanta/second/cm ² , at least 80% of the total supply of energy is within the wavelength band of 400 to 600 nm. The invention also includes control of the period of time during which the irradiation is supplied.

WO 1998011946 describes an apparatus and methods for enhancing fowl productivity by providing a light source having a desired output spectrum, and for illuminating the light source close to or actually on the head of the fowl. The novel 'local' illumination provided thereby eliminates significant variations in illumination applied to the fowl in accordance with the prior art due to variations of their location relative to an illumination source. This enhances economy because feeding costs resulting from over- illumination are reduced without decreasing growth and reproductivity.

SUMMARY OF THE INVENTION The prior-art lighting apparatus and method as described above do not address problems of feather picking. Feather picking, or more precisely injurious feather picking, is one of the gravest issues in the poultry industry. It surprisingly appeared that it can be significantly reduced, if not eliminated, by providing a certain quantity of UV-A radiation next to the light visible to humans. The vision of birds seems to extend well into the UV-A range of wavelengths. It has also been found that most types of birds show patterns of reflection in the UV-A region. Therefore, a chicken, which shows a uniform color to humans, can show patterns in the UV that are visible to other chickens. Like many other birds, chickens may use these patterns in the plumage of their conspecifics in order to recognize individuals and to establish the rank order (picking order). Furthermore, providing UV-A light seems to enrich the visual environment of birds.

Sunlight in Europe or northern America typically contains UV-A of the order of 6 % and UV-B of the order of 0.16 %. Typical illumination levels outdoors can run up to 100.000 lux on a sunny day. At the edge of woods or under shrubberies, where chickens naturally like to roam, illumination is normally several orders of magnitude lower. Most chicken houses are illuminated at a level of 5 lux. Currently, EU legislation is moving towards 20 lux, and some 'organic' farmers go up to 80 lux.

It is evident that, to be able to see or distinguish a color, light of these wavelengths must exceed a certain threshold level. If a light source emitting a spectrum identical to that of the sun as it arrives at the earth's surface were used to get a light intensity of 10 lux, the UV-A level would still be only around 1/1000th or even 1/lO.OOOth of that of the sun at normal outdoor light levels. Therefore, if a light source is to be designed to enable avian UV vision indoors at lower light levels, the UV-A levels must be chosen to be significantly higher.

It appeared that the use of lamps emitting at values lower than about 10% or 12 % of UV-A (relative to the total quantity of UV-A, UV-B and visible light) hardly, if at all, has the beneficial effect of suppressing injurious feather picking among laying hens.

Hence, it is an object of the present invention to provide an alternative light source which can be preferably used to improve birds' well-being and/or to reduce or substantially eliminate feather picking among birds, and, in addition, can also be preferably used for general lighting, preferably obviating one or more of the described drawbacks of prior-art lamps.

To this end, the invention provides a luminescent lamp for lighting birds, particularly poultry, which lamp is arranged to generate light in the UV-A and visible range, the luminescent lamp comprising a UV-A transmissive discharge vessel enclosing, in a gastight manner, a discharge space provided with an inert gas and mercury and comprising discharge means for maintaining a discharge in the discharge space during operation of the luminescent lamp, wherein the discharge vessel comprises a discharge vessel surface and at least a part of the surface of the discharge vessel is provided with a luminescent material layer comprising a luminescent material, the luminescent material comprising a UV-A- luminescent material, a blue-luminescent material, a green- luminescent material and a red- luminescent material, wherein the luminescent material layer preferably comprises at least 20 wt.%, such as 20-50 wt.%, preferably at least 25 wt.%, of the UV-A- luminescent material relative to the total quantity of luminescent materials in the luminescent material layer, and wherein the UV-A- luminescent material comprises one or more luminescent materials selected from the group consisting of cerium-doped strontium aluminate (SAC), bismuth- doped gadolinium lanthanum borate (GLBB), cerium magnesium aluminate (CAM), europium-doped strontium tetraborate (SBE), lead-doped strontium barium magnesium silicate (SMS), lead-doped barium disilicate (BSP), cerium-doped yttrium phosphate (YPO) and cerium-doped lanthanum phosphate (LAP: Ce); the blue-luminescent material comprises one or more luminescent materials selected from the group consisting of europium-doped barium magnesium aluminate (BAM), europium-doped strontium calcium chloroapatite (SCAP), europium and manganese-doped barium magnesium aluminate (BBG or BAM:Eu,Mn), and europium-doped strontium aluminate (SAE); the green- luminescent material comprises one or more luminescent materials selected from the group consisting of cerium and terbium-doped lanthanum phosphate (LAP:Ce,Tb), terbium-doped cerium magnesium aluminate (CAT), terbium-doped cerium gadolinium magnesium borate (CBT) and cerium-doped yttrium aluminate garnet (YAG:Ce); and the red-luminescent material comprises one or more luminescent materials selected from the group consisting of europium-doped yttrium oxide (YOX or YOE) and manganese and terbium-doped cerium gadolinium magnesium borate (CBTM).

Light sources of this type may be suitably used particularly in bird farming or bird husbandry, and they may be used to prevent or reduce feather picking and/or to improve the well-being of birds, particularly poultry.

Whereas it was often attempted in the prior art to obtain light sources with a high color rendering index, mimicking the sun, a substantially pure tri-band lamp and UV-A light appears to provide an advantageous alternative. Substantially all of these UV-producing lamps according to the prior art are colloquially referred to as 'full spectrum lamps', i.e. they use a large number of luminescent materials or luminescent materials with a wide emission spectrum (such as halophosphates). The emission spectrum of these lamps has a relatively continuous character, certainly when compared with a three-phosphor fluorescent lamp, such as a typical '80 series' luminescent lamp. Typically, these light sources are claimed to be natural, i.e. close to the solar spectrum and were thus considered to have positive effects on the health and well-being of humans and animals.

One of the ways to provide the required UV-A levels also seemed to be the installation of lamps which almost only emit UV-A, such as 'blacklight-blue' lamps in between the light sources emitting light in the human range of vision. In practice, this appears to cause two problems. Because of the locally very high intensity of UV-A, such lamps attract a large number of insects, effectively shielding the lamp. Taking the ratio of UV and human visual radiation into account, about one out of every four or five installed lamps would have to be of the UV-A emitting type. In many cases, homogeneity of the light distribution is very important, particularly in bird housing, such as poultry housing. This also applies to the UV radiation. Consequently, installing UV-A lamps in addition to an existing 'human visual' lighting installation is not an option. The invention therefore provides a luminescent lamp which provides both UV-A and visible light.

The luminescent lamp according to the invention can be particularly used as a light source in a poultry farmhouse. Furthermore, this lamp can also be used as a light source in bird industry for reducing (or substantially preventing) feather picking. In particular, this lamp can be used to provide light having a UV-A contribution (in W) of at least 15 % relative to the total quantity of UV-A, UV-B and visible light (in W). According to a further aspect, the invention also provides a poultry farmhouse with interior lighting comprising one or more luminescent lamps according to the invention.

According to a further aspect, the invention also provides a bird cage with (interior) lighting comprising one or more luminescent lamps according to the invention. According to yet another aspect, the invention provides a method of bird farming, such as poultry farming, including lighting birds with one or more luminescent lamps according to the invention.

Birds belong to the class of Aves. The term poultry, as known to the person skilled in the art, may refer to the category of domesticated birds kept by some humans for their eggs, meat and/or feathers. These are most typically members of the super order galloanserae (fowl), particularly the order galliformes (which includes chickens and turkeys) and the family of Anatidae (in the order Anseriformes), commonly known as "waterfowl" (e.g. domestic ducks and domestic geese). Poultry also includes other birds which humans kill for their meat, such as pigeons, doves or pheasants. Characteristic poultry birds are chicken, duck, goose, peacock, swan and turkey. The term "bird" is used, since the luminescent lamp and method of the invention may not only be advantageous to poultry, but also to birds in general, such as domestic birds like the canary, parakeet, etc. The term "luminescent lamp" refers to lamps that are sometimes also referred to as phosphorescent lamps or fluorescent lamps. An example of such a lamp is a compact luminescent lamp (CFL: compact fluorescent lamp).

There are several definitions of the sub-division of the electromagnetic spectrum into ultraviolet and visual ranges. Here, the wavelength ranges are chosen as: UV- B, 280 nm to 320 nm; UV-A, 320 nm to 400 nm and human visual, 400 nm to 780 nm. The 'content' of each of these is then expressed as the fraction of the spectral power emitted in that range relative to the total radiation output power of all three ranges, e.g.:

UV-A radiation is not visible to humans (at least not to adults). However, many animals can see UV-A. If these are kept indoors, without UV-A containing solar radiation entering unfiltered, they will miss a considerable amount of visible information. The light generated by the luminescent lamp comprises a UV-A part and a visible part and optionally a UV-B part. Note that, in general, UV radiation is not really considered to be light, since it is not visible to humans. However, for the sake of simplicity, the UV-A and visible output of the lamp during use is herein indicated by the term "light".

It also appears that chickens have a flicker fusion frequency at about 160 Hz, which is much higher than that of humans and much higher than the flicker frequency of fluorescent lamps driven at electromagnetic gear at a 50 Hz or 60 Hz electric power frequency. It is therefore recommended to use (high-frequency) electronic drivers when lighting bird houses, such as poultry farmhouses, or bird cages. Hence, in a specific embodiment, the luminescent lamp of the invention further comprises a driver which is arranged to provide electric power to the luminescent lamp during its use, at an electric power frequency of at least 150 Hz, more preferably at least about 160 Hz.

The luminescent materials are selected from the group of materials indicated in the Table below.

Short name Name Formula ; main ; wavelength ⁽¹⁾

Blue

BAM Barium Magnesium BaMgAl ₁₀ Oi ₇ :Eu ²⁺ I 451 Aluminate:Eu SCAP Strontium Calcium Chloroapatite (Ca,Sr,Ba) ₅ (P0 ₄ ) ₃ Cl:Eu ^z * [ 454

BBG Barium Magnesium Aluminate BaMgAl ₁₀ Oi ₇ :Eu ²⁺ ,Mn ²⁺ I 450+520

(or BAM:Eu,Mn) Europium Manganese

^" SAE Strontium Aluminate :Eu Sr ₄ AIi ₄ O ₂ SiEu ²⁺ 490

Green

LAP:Ce,Tb Cerium Lanthanum Phosphate:Tb (Ce,La)PO ₄ :Tb I 544

CAT Cerium Magnesium (Ce ₅ Tb)MgAl ₁₁ Oi ₉ I 543 Aluminate: Tb

CBT Cerium, Gadolinium, Magnesium (Ce,Gd)MgB ₅ Oi ₀ :Tb I 542 B orate: Tb

YAG:Ce Yttrium Aluminate: Ce Y ₃ Al ₅ Oi ₂ :Ce I 534

Red

YOX Yttrium Oxide :Eu Y ₂ O ₃ :Eu ³⁺ I 611

(or YOE)

CBTM Cerium Gadolinium Magnesium (Ce,Gd,Tb)MgB ₅ Oi ₀ :Mn ²⁺ I 627 Borate:Tb,Mn

Main wavelength is emission maximum in emission spectrum

Instead of the luminescent materials mentioned above, analogs thereof or mixtures with analogs thereof may also be used. For instance, characteristic luminescent materials may be selected from the group consisting of BaMgAlioOi7:Eu ²⁺ (BAM), and analogs materials (for instance, wherein one or more of Ba, Mg, Al (and O) are at least partly substituted with other cations (or anions, respectively)), LaPO ₄ :Ce ³⁺ ,Tb ³⁺ (LAP), and analogs materials (for instance, wherein particularly La may be at least partly substituted with other cations), Y ₂ OsIEu ³⁺ , and analogs materials (for instance, wherein Y is at least partly substituted with other cations), and YsAIsOi ₂ )Ce ³⁺ , and analogs materials (for instance, wherein one or more of Y, Al (and O) are at least partly substituted with other cations (or anions, respectively)). For the sake of clarity, possible (further) codopants have not been included in this general description of characteristic luminescent materials. Analogs materials are known to the person skilled in the art. Such materials have different spectral distributions of the emissions, because the positions of the emissions are different and/or the relative intensities of the emissions are different, respectively. In a preferred embodiment, the luminescent material exclusively consists of the luminescent material as indicated in the Table above. This implies that the luminescent material layer may further comprise a binder or binder remainders or materials such as alon C, or any other components known to the person skilled in the art, but only one or more of each of the four categories (UV-A, blue, green and red) is present as luminescent material, with no other materials known in the art as UV-A or visible emitter.

In one embodiment, the luminescent material comprises as RGB luminescent materials a mixture of at least Europium-doped Barium Magnesium Aluminate (BAM), Terbium-doped Cerium Lanthanum Phosphate (LAP) and Europium-doped Yttrium Oxide (YOX). In a further embodiment, the mixture comprises 3-22 wt.% BAM, 31-47 wt.% LAP and 31 -67 wt.% YOX. A mixture of BAM, LAP and YOX may provide an efficient visible light-emitting source for use in combination with a UV-A luminescent material.

In yet another preferred embodiment, only one luminescent material per category (UV-A, blue, green and red (RGB)) is comprised in the luminescent material. The luminescent material layer preferably comprises SBE, BAM, LAP:Ce,Tb and YOX. More preferably, the luminescent material of the luminescent material layer substantially only consists of SBE, BAM, LAP:Ce,Tb and YOX, and no other luminescent material is present in the luminescent material layer.

The UV-A luminescent material is particularly selected from the group consisting of europium-doped strontium tetraborate (SBE), lead-doped strontium barium magnesium silicate (SMS), and lead-doped barium disilicate (BSP), more particularly from the group consisting of europium-doped strontium tetraborate (SBE) and lead-doped barium disilicate (BSP), particularly SBE. In another embodiment, YPO is applied as UV-A luminescent material. In a further embodiment, the UV luminescent material is configured to emit UV-A light between 320 and 400 nm, preferably between 350 nm and 400 nm.

In a preferred embodiment, the luminescent material layer comprises at least 10 wt. % of the UV-A- luminescent material relative to the total quantity of luminescent materials in the luminescent material layer, more preferably at least 20 wt.%. Particularly in this way, the required amount of UV-A radiation may be obtained, while still also having (sufficient) visible light. In another preferred embodiment, the luminescent material layer therefore comprises about 10-50 wt.%, particularly at least about 20 wt.%, such as preferably about 20-50 wt.%, and more particularly about 25-50 wt.%, such as about 25-45 wt.%, of the UV-A- luminescent material relative to the total quantity of luminescent materials in the luminescent material layer.

The luminescent materials are particularly arranged to provide light during use of the luminescent lamp, having a UV-A contribution (in W) of at least 13%, more preferably at least 15% relative to the total amount of UV-A, UV-B and visible light (in W). As will be clear to the person skilled in the art, the term "during use" indicates the state of the luminescent lamp when the discharge is present and luminescent material emits light upon absorption of radiation from the discharge. The luminescent materials are particularly arranged to provide light during use of the luminescent lamp, having a UV-A contribution (in W) in the range of about 13-50%, preferably aboutl5-50%, more preferably about 20-50% relative to the total amount of UV-A, UV-B and visible light (in W). The UV-A contribution (in W) is preferably in the range of about 15-30%, more preferably about 15-25 %, even more preferably at least about 18%, relative to the total amount of UV-A, UV-B and visible light (in W) (provided by the luminescent lamp at nominal operation). When a plurality of luminescent lamps is applied, these values may differ from lamp to lamp, and the total amount of UV-A of an individual luminescent lamp may be higher (or lower) such as, for instance, up to about 50%. However, the integrated light of the plurality of luminescent lamps will be preferably in the range of about 15-30%, particularly 15-25%, more preferably at least about 18%, relative to the total amount of UV-A, UV-B and visible light (in W) of the plurality of luminescent lamps. In a further embodiment, the luminescent lamp is arranged to have a column efficiency of at least about 60 lm/W during use, preferably at least about 70 lm/W, more preferably at least about 80 lm/W. As is known to the person skilled in the art, the efficiency of luminescent lamps (sometimes also referred to as fluorescent light sources), primarily determined by the luminescent material composition, is influenced by a number of factors. A combination or mixture of luminescent materials, which will satisfy the preferred efficiency in a straight T8 or T12 TL lamp, may thus not be satisfactory when used in a compact fluorescent lamp. To correct this, the following correction factors are used to calculate the column efficiency for a fluorescent source, as compared to a straight T8 (25.4 mm diameter)

36W fluorescent tube lamp: wall load losses (ranging from T12 to T8, from T8 to T5, or from T5 to CFL): -5 % per step shielding losses (in case of CFL): -15 % losses of integrated driver (with CFL-i): -15 % outer bulb or cover for CFL: -5 %

In all cases, the lamp power is reduced by 2W due to electrode losses.

As an example, a phosphor mix, which yields a column efficiency of 100 lm/W, will result in a lamp efficiency of 94 lm/W in a 36W TLD, but will only yield 49 lm/W in a 1OW CFL-I with an outer bulb. To compensate this effect, the column efficiency of a 36W T8 will be used for fluorescent lamps as the relevant source efficiency (set at

100%).

As a consequence of having a broad, continuous spectrum and producing UV-

A, the source efficiency of prior-art lamps producing a significant amount of UV does not exceed 50 lm/W. Those which exceed this value generally have a much lower part of UV-A radiation in relation to the total UV-A and visible radiation.

In a further preferred embodiment, the luminescent lamp is particularly arranged to provide, during use, light having an Ra8 in the range of 65-80.

The discharge vessel comprises a wall of glass, which allows transmission of

UV-A light and visible light. Any suitable glass known in the art may be applied. In a specific embodiment, the discharge vessel comprises a wall of glass having the following composition:

SiO ₂ 73.1% +/- 0.5;

Al ₂ O ₃ 2.15% +/-0.1;

Na ₂ O 16.8% +/-0.3; K ₂ O 0.6% +/- 0.1;

MgO+CaO 7.1% +/-0.2; and optionally one or more of MnO <0.035%; Fe ₂ O ₃ <0.15%; SO ₃ <0.15%; and TiO ₂ +/-

0.025. All percentages are weight percentages, relative to the total weight of the glass. In a preferred embodiment, a discharge vessel is thus applied with walls (glass walls), obtainable by melting SiO ₂ 73.1% +/- 0.5; Al ₂ O ₃ 2.15% +/-0.1; Na ₂ O 16.8% +/-0.3; K ₂ O 0.6% +/- 0.1; MgO+CaO 7.1% +/-0.2; and optionally one or more of MnO <0.035%; Fe ₂ O ₃ <0.15%; SO ₃ <0.15%; and TiO ₂ +/- 0.025 (percentages are weight percentages, relative to the total weight of the mixture for providing the glass) to a melt and shaping the melt to form a discharge vessel or a part thereof. Parts may be melted together after coating with the luminescent material.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which corresponding reference symbols indicate corresponding parts, and in which:

Figures Ia-Ic schematically show in general some embodiments according to the invention;

Figure 2 schematically shows a poultry farmhouse with luminescent lamps according to an embodiment of the invention; and

Figure 3 schematically shows column efficiency (lm/W) and UV-A content (%) (relative to the total amount of UV-A, UV-B and visible) of prior-art lamps. For the sake of clarity, optional further optics or (other) peripheral equipment, such as reflectors, mirrors, heat sinks, diffusers, further light guides, power sources, electric wires, luminescent materials, etc. are not shown in the drawings if not necessary for comprehension of the Figures.

DESCRIPTION OF EMBODIMENTS

Figure Ia schematically shows an embodiment of a luminescent lamp 1 ("lamp") according to the invention. This lamp 1 may be used for lighting poultry (see also Figure 2) and is arranged to generate light 100, inter alia, for lighting birds (such as poultry). This light 100 is in the UV-A and visible range. The luminescent lamp 1 comprises a UV-A transmissive discharge vessel 10 enclosing, in a gastight manner, a discharge space 20 provided with an inert gas 21 and mercury 22.

The term "UV-A transmissive discharge vessel 10" herein particularly relates to a discharge vessel having a mean transmission (over the wavelength in the UV-A wavelength range) in the UV-A wavelength range of at least about 20%, preferably at least about 50%. Particularly the transmission at the main wavelength of the UV-A luminescent material or materials applied is at least about 50%, preferably at least about 80%. Transmission is measured in accordance with methods known in the art, and may include perpendicular irradiation of a side (surface 1 Ib or 1 Ia, see below) of the object for which the transmission has to be evaluated (here, for instance, the discharge vessel 10 (i.e. from the exterior to the discharge space 20, or vice versa)) with the radiation having the wavelength for which the transmission has to be evaluated, and collection of the light of the same wavelength at the other side of the object (here the surface 1 Ia or 1 Ib (see below), respectively). The ratio of transmitted to irradiated light provides the transmission for the light of the specific wavelength.

The luminescent lamp 1 comprises discharge means 25, particularly electrodes, for maintaining a discharge 26 in the discharge space 20 during use of the luminescent lamp 1. The electrodes may be arranged internally of the discharge space 20, as schematically shown, but may also be placed externally thereof. In the latter embodiment (not shown), the discharge 26 may be created within the discharge space 10 via inductive coupling.

The discharge vessel 10 comprises a discharge vessel surface 11. At least a part of the surface 11 of the discharge vessel 10 is provided with a luminescent material layer (not shown, see below and see Figures Ib and Ic).

The discharge vessel 10 comprises an inner surface 11a and an outer surface 1 Ib. The phrase "at least a part of the surface 11 of the discharge vessel 10 is provided with a luminescent material layer" indicates that at least a part of the inner surface 11a and/or a part of the outer surface 1 Ib of the discharge vessel 10 are provided with the luminescent material layer or layers 50. Substantially the entire (i.e. at least about 90% of the respective) inner surface 11a and/or the outer surface l ib of the discharge vessel 10 are preferably provided with a luminescent material layer. In general, only the inner surface 1 Ia or the outer surface 1 Ib of the discharge vessel 10 will be provided with a luminescent material layer. Furthermore, the luminescent lamp 1 may comprise a driver 70 arranged to control the power and frequency thereof to the discharge means 25.

Figures Ib and Ic schematically show two possible embodiments of arrangements of the luminescent material layer 50. Figure Ib schematically shows an embodiment in which the luminescent material layer 50 is arranged at the inner surface 11a, i.e. downstream of the wall of the discharge vessel, whereas Figure Ic schematically shows an embodiment in which the luminescent material layer 50 is arranged at the outer surface 1 Ib, i.e. downstream of the wall of the discharge vessel, denoted by reference numeral 12. The terms "upstream" and "downstream" relate to an arrangement of items or features relative to the propagation of light from the light source, wherein, relative to a first position within a beam of light from the light source, a second position in the beam of light closer to the light source is "upstream", and a third position within the beam of light further away from the light source is "downstream".

Figures Ib and Ic show the luminescent material layer 50 attached (as a coating) to the inner surface 1 Ia or outer surface 1 Ib, respectively, which layer 50 comprises luminescent material 60 comprising a UV-A- luminescent material 61, a blue-luminescent material 62, a green-luminescent material 63 and a red-luminescent material 64. The UV-A- luminescent material (61) comprises one or more luminescent materials selected from the group consisting of cerium-doped strontium aluminate (SAC), bismuth-doped gadolinium lanthanum borate (GLBB), cerium magnesium aluminate (CAM), europium-doped strontium tetraborate (SBE), lead-doped strontium barium magnesium silicate (SMS), lead-doped barium disilicate (BSP), cerium-doped yttrium phosphate (YPO) and cerium-doped lanthanum phosphate (LAP:Ce). The blue- luminescent material (62) may comprise one or more luminescent materials selected from the group consisting of europium-doped barium magnesium aluminate (BAM), europium-doped strontium calcium chloroapatite (SCAP), europium and manganese-doped barium magnesium aluminate (BBG or BAM:Eu,Mn), and europium-doped strontium aluminate (SAE). The green- luminescent material 63 may comprise one or more luminescent materials selected from the group consisting of cerium and terbium-doped lanthanum phosphate (LAP:Ce,Tb), terbium-doped cerium magnesium aluminate (CAT), terbium-doped cerium gadolinium magnesium borate (CBT) and cerium- doped yttrium aluminate garnet (YAG:Ce). The red- luminescent material 64 may comprise one or more luminescent materials selected from the group consisting of europium-doped yttrium oxide (YOX or YOE) and manganese and terbium-doped cerium gadolinium magnesium borate (CBTM).

Figure 2 schematically shows a poultry farmhouse 200 with interior lighting 210 comprising one or more luminescent lamps 1 as described above. Birds 201, for instance, chicken, are shown by way of example.

EXAMPLES

Comparative examples

Analysis of prior-art lamps has shown that these lamps contain a combination of phosphors, sometimes including a halophosphate phosphor. However, these prior-art lamps have a relatively inferior quality in comparison with the luminescent lamp according to the invention. An overview of lamps is given in Figure 3. As can be derived from this Figure, none of the evaluated prior-art lamps provides a column efficiency of at least about 60 lm/W and a UV-A content of at least about 15% relative to the total amount of UV-A and visible light (in W).

The following types of lamps were tested:

Examples according to the invention Luminescent material mixtures were applied to discharge vessels by means of standard coating techniques, and T5 28W / T5 54W / PLS 7W lamps were made. The optical data of the lamps during use and the composition of the luminescent material mixtures applied are indicated in Table 1. Mixtures comprising 250 g of luminescent material, 200 ml of binder, 12.5 ml of a 10% Alon-C butyl acetate solution and 200 ml of butyl acetate were applied for the lamps of Tables 1, 2a/2b, and 4a/4b. The applied luminescent material mixtures and the optical data of the lamps during use are indicated in Tables 2a and 2b, respectively. Table 2a gives the values for the UV-A output and other details; Table 2b gives the data as obtained after measuring the lamp. Table 4a gives the values for the UV-A output and other details;

Table 4b gives the data as obtained after measuring the lamp. Figure 3 relates to data of prior- art lamps.

Where % UV-A is indicated in the Table, it relates to the % in W relative to the total W in the visible, UV-B and UV-A range. Most lamps were made by depositing the suspension on the internal area of the discharge vessel and then drying at room temperature in air (flow 10 1/min.). A coating weight of about 3 mg/cm ² was obtained.

Lamps of the Philips PL-S 4P 7W type were made by means of standard PL processing methods (coating, drying, sintering (5 minutes at 520 ⁰ C in air)), dividing the glass tube (200 mm into two parts of 100 mm with one end closed), bridging at 5 - 10 mm from the closed part of the tubes; electrode/mercury sealing and pumping/filling. 3 mg of a mercury dosage and a 10 mBar Ar gas-filling were used.

Table 1

850: Ra8>80; Tc=5000; 865: Ra8>80; Tc=6500 etc.

Table 4a: PLS 7W lamps

Luminescent lamps according to the invention were compared with state-of- the-art luminescent lamps in poultry farms. Use of luminescent lamps of the invention leads to a reduction in, feather picking among the poultry as compared to use of prior-art lamps.

In one example, the UV-A luminescent material content was varied and the UV-A output was measured. The following results were obtained:

Use of the adverb "substantially" in this description and claims, such as in

"substantially all emission" or in "substantially consists", will be understood by the person skilled in the art. Likewise, the preposition or adverb "about" will be understood. For instance, "about 90°" may thus also relate to "90°". Where appropriate, "substantially" or "about" may also include embodiments mentioning the adverbs "entirely", "completely", "exactly", and the adjective or pronoun "all", etc. Hence, "substantially" may also be removed in embodiments. Where applicable, "substantially" may also relate to 90% or more, such as 95% or more, particularly 99% or more, more particularly 99.5% or more, including 100%. The verb "comprise" also includes embodiments in which it means "consists of.

Furthermore, the terms first, second, third and the like in the description and claims are used to distinguish between similar elements and are not necessarily used to describe a sequential or chronological order. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in sequences other than those herein described or illustrated. The devices mentioned hereinbefore are described, inter alia, during operation.

As will be clear to the person skilled in the art, the invention is not limited to methods of operation or devices in operation.

It should be noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design many alternative embodiments without departing from the scope of the appended claims. In the claims, any reference signs placed between parentheses shall not be construed as limiting the claim. Use of the verb "comprise" and its conjugations does not exclude the presence of elements or steps other than those stated in a claim. The article "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.