DE102006037859A1 - External electrode fluorescent lamp for background lighting of displays or screens, comprises a covering glass having an inner coating, which contains doping materials, and a gas mixture - Google Patents

Abstract

The external electrode fluorescent lamp for background lighting of displays or screens, comprises a covering glass (110) having an inner coating, which contains doping materials, and a gas mixture. The inner coating has a low work function W afor the electrons of 0-3 eV. The sum of the amounts of doping materials in the covering glass has a lower limit of = 30 wt.% and an upper limit of >= 70 wt.%. The doping materials have high secondary electrons emission rate of greater than 0.1. The covering glass and/or the coating has a large electronic density of state in the valence band. The external electrode fluorescent lamp for background lighting of displays or screens, comprises a covering glass (110) having an inner coating, which contains doping materials, and a gas mixture. The inner coating has a low work function (W a) for the electrons of 0-3 eV. The sum of the amounts of doping materials in the covering glass has a lower limit of = 30 wt.% and an upper limit of >= 70 wt.%. The doping materials have high secondary electrons emission rate of greater than 0.1. The covering glass and/or the inner coating has a large electronic density of state in the valence band. The inner coating has a huge band gap of greater than 4 eV, so that a coating is enabled over the fluorescent dye. The inner coating is brought to a thickness of 0.3 nm to 10 mu m. An independent claim is included for a covering glass of an external electrode fluorescent lamp.

Description

The The invention relates to an EEFL-type fluorescent lamp whose efficiency is optimized.

It is known for the backlighting of TFT flat screens Fluorescent lamps usually thin glass tubes be used. As a recent development, there are lamps, in which the electrical power coupled via AC voltage These are so-called EEFLs (external electrode fluorescent lamps). In this type of lamp, no metal electrodes are passed through the glass passed. With the glass as a dielectric, for example, with an outer metal cap is provided as well as the ionizing gas, such as mercury or a noble gas, a condenser is created inside the tube be coupled to the electrical power as AC voltage can. The glass serves not only as a dielectric in the capacitor, but the inside of the glass tube lying surface forms the cathode.

At present, the same glasses are used for EEFL-type fluorescent lamps as for conventional fluorescent lamps, whereby, for example, the metal electrodes can also be passed through the glass (CCFLs; cold cathode fluorescence lamp). For example, in the publications WO 2006/006831 A1 and WO 2006/011752 A1 EEFL-type fluorescent lamps and their applications are described. However, these are not optimized in terms of their efficiency. No statements are made about the glasses used.

In the DE 20 2005 004 459 U1 describes glasses for lamps with external electrodes, where the quotient of the loss angle and the dielectric constant is to apply:

These glasses have optimized dielectric properties.

The Inventors have found that the efficiency of a fluorescent lamp then biggest and the ignition voltage the lamp is at its lowest when the bulb of the lamp, so it is modified as much as possible size Possesses or denies the possibility of emitting secondary electrons, when a noble gas ion is neutralized there. One speaks of also the so-called "Auger neutralization", in particular for the Neutralization of noble gas ions on metal surfaces known is.

For plasma screens (PDP) it is already discussed whether the secondary electron emission rate can be reduced by a suitable coating of the glasses. An overview of this topic is for example the work of JP Boeuf, J. Phys. D: Appl. Phys. 36, R53 (2003) refer to. In Uhm et al., Appl. Phys. Lett. 78, 592 (2001) the influence of the secondary electron emission rate on the ignition voltage of a plasma pixel is described Lim et al. J. Appl. Phys. 94, 1 (2003) the work function of crystalline MgO is determined.

Thereby, that glasses Isolators represent is first once the probability for the sending of secondary Electrons very low, if an ion from the gas plasma at the surface of the Cathode is neutralized. This results in the high ignition voltage of fluorescent lamps. Due to the high ignition voltage must in Flat screen high voltages are used, what is more Represents security risk. Furthermore, the efficiency decreases, since it during a Half-wave of the driving AC voltage can come to dead times.

It is therefore an object of the present invention, the above-mentioned To avoid problems of the prior art and fluorescent lamps of the EEFL type providing the disadvantages described do not have.

Surprisingly, it has now been discovered that EEFL-type fluorescent lamps then have a particularly high efficiency and at the same time have the lowest possible starting voltage for the lamp when glasses and / or glass coatings capable of carrying high-probability secondary electrons are used send out. This probability can be expressed by the work function W _a for the electrons. The work function is the smallest energy needed to remove an electron from an uncharged solid. Accordingly, according to the invention, glasses and / or glass coatings are to be used in which the lowest possible exit work W _a can be set.

• (1) das Hüllenglas eine niedrige Austrittsarbeit W_a für die Elektronen von < 5 eV, bevorzugt 0 eV < W_a < 5 eV, besonders bevorzugt 0 eV < W_a < 4 eV, ganz besonders bevorzugt 0 eV < W_a < 3 eV aufweist und mindestens einen Dotierstoff enthält, ausgewählt aus – der Gruppe (a), bestehend aus BaO, CaO, MgO, SrO, MgF₂, AlN, Al₂O₃, und/oder Mg_1-x-ySr_xCa_yO, in einer Menge im Bereich von 3 bis 70 Gew.-%, besonders bevorzugt von 5 bis 60 Gew.-%, ganz besonders bevorzugt von 10 bis 60 Gew.-%; und/oder – aus der Gruppe (b), bestehend aus La₂O₃, Bi₂O₃ und/oder PbO, in einer Menge im Bereich von 3 bis 80 Gew.-%, besonders bevorzugt von 5 bis 75 Gew.-%., ganz besonders bevorzugt 10 bis 65 Gew.-%; und/oder
• (2) das Hüllenglas eine (Teil-)Innenbeschichtung aufweist, die eine niedrige Austrittsarbeit W_a für die Elektronen von < 5 eV, bevorzugt 0 eV < W_a < 5 eV, besonders bevorzugt 0 eV < W_a < 4 eV, ganz besonders bevorzugt 0 eV < W_a < 3 eV aufweist, wobei die Innenbeschichtung mindestens einen Dotierstoff enthält oder aus mindestens einem Dotierstoff besteht, ausgewählt aus – der Gruppe (a), bestehend aus BaO, CaO, MgO, SrO, MgF₂, AlN, Al₂O₃, und/oder Mg_1-x-ySr_xCa_yO, in einer Menge im Bereich von 3 bis 70 Gew.-%, besonders bevorzugt von 5 bis 60 Gew.-%, ganz besonders bevorzugt von 10 bis 60 Gew.-%; und/oder – aus der Gruppe (b), bestehend aus La₂O₃, Bi₂O₃ und/oder PbO, in einer Menge im Bereich von 3 bis 80 Gew.-%, besonders bevorzugt von 5 bis 75 Gew.-%., ganz besonders bevorzugt 10 bis 65 Gew.-%.

The object is thus achieved according to the invention by a fluorescent lamp of the EEFL type for the backlight of displays or screens, comprising a glass envelope, wherein

• (1) the cladding glass has a low work function W _a for the electrons of <5 eV, preferably 0 eV <W _a <5 eV, more preferably 0 eV <W _a <4 eV, most preferably 0 eV <W _a <3 eV and at least one dopant selected from the group (a) consisting of BaO, CaO, MgO, SrO, MgF ₂ , AlN, Al ₂ O ₃ , and / or Mg _1-xy Sr _x Ca _y O, in in an amount ranging from 3 to 70% by weight, be more preferably from 5 to 60% by weight, most preferably from 10 to 60% by weight; and / or - from the group (b) consisting of La ₂ O ₃ , Bi ₂ O ₃ and / or PbO, in an amount in the range from 3 to 80% by weight, particularly preferably from 5 to 75% by weight. %, most preferably 10 to 65 wt .-%; and or
• (2) the cladding glass has a (partial) internal coating which has a low work function W _a for the electrons of <5 eV, preferably 0 eV <W _a <5 eV, particularly preferably 0 eV <W _a <4 eV, especially preferably 0 eV <W _a <3 eV, wherein the inner coating contains at least one dopant or consists of at least one dopant selected from the group (a) consisting of BaO, CaO, MgO, SrO, MgF ₂ , AlN, Al ₂ O ₃ , and / or Mg _1-xy Sr _x Ca _y O, in an amount ranging from 3 to 70 wt .-%, particularly preferably from 5 to 60 wt .-%, most preferably from 10 to 60 wt .-%; and / or - from the group (b) consisting of La ₂ O ₃ , Bi ₂ O ₃ and / or PbO, in an amount in the range from 3 to 80% by weight, particularly preferably from 5 to 75% by weight. %., Most preferably 10 to 65 wt .-%.

The teaching according to the invention accordingly provides very specific glasses or coatings for glasses which contain at least one dopant, particularly preferably a combination of several dopants, which make it possible for the envelope glass used and / or the inner coating of the envelope glass to be produced owing to the low work function W _a for which the electrons have an optimum efficiency of the EEFL-type fluorescent lamp. In addition, this makes it possible to lower the ignition voltage of the fluorescent lamp of the EEFL type according to the invention to an extraordinarily low level.

In the present invention, the sheath glasses are not particularly limited as far as they are suitable for EEFL-type fluorescent lamps. According to a variant (1) according to the invention, these base glasses have a low work function W _a for electrons. This is achieved by doping the glasses with one or more dopants selected from group (a) and / or (b). Thus, for example, alkaline earth metal ions (group (a)) in a preferred minimum concentration of 3 wt .-%, preferably from 5 wt .-%, in particular 10 wt .-%. be included. These are, for example, BaO, CaO, MgO, SrO, MgF ₂ or also Mg _1-xy Sr _x Ca _y O. These can be used individually or in combination of two, three, four or more.

In addition to the alkaline earth metal ions mentioned, it is also possible to use aluminum compounds, such as Al ₂ O ₃ and / or AlN, in the glasses according to the invention. The preferred range in which these dopants contribute to a desirably low work function W _{a of} the cladding glass is from about 3 to about 70 weight percent, more preferably from about 10 to about 60 weight percent.

Furthermore exists alternatively or additionally also the possibility Heavy metals in the glasses to include (group (b)). These are, for example to compounds of lanthanum, bismuth and / or lead.

According to the invention can according to a another variant (2) a (partial) inner coating in the glass envelope be provided, the at least one dopant, preferably a Combination of the group (a) and / or (b) described above. The quantity ranges The dopants from group (a) are preferably in one range from about 3 to about 70% by weight. The quantity ranges of Dopants from group (b) are preferably in one range from about 3 to about 80% by weight. As already stated, the Dopants from the group (a) and (b) are also combined.

The Coating the sheath glass on the inside surface of the glass is preferably only a partial coating, in particular on selected Areas of the sheath glass. Conveniently, the inner coating is only provided where ions of the in the Lamp are discharged, i. E. in and around the area where the metal contacts of the cathode of the fluorescent lamp are located.

The Layer thicknesses for the inner coating of the fluorescent lamp of the EEFL type according to the invention are preferably in a range of about 0.3 nm to about 10 μm; in individual cases, the However, these values are also significantly below or exceeded become. In addition to the dopant (s) may also contain conventional additives in the coating be.

Particularly preferably, the sum of the existing amount of the dopants from group (a) and group (b) in the glass envelope has a lower limit of ≥ 15 wt .-%, preferably ≥ 20 wt .-%, most preferably ≥ 30 wt .-% and a Upper limit of ≦ 80% by weight, preferably ≦ 75% by weight, very particularly preferably ≦ 70% by weight. In the same way, preferably the sum of the existing amount of dopants from group (a) and group (b) in the (partial) inner coating has a lower limit of ≥ 15 wt .-%, preferably ≥ 20 wt .-%, most preferably ≥ 30 wt .-% and a Obergren ze of ≦ 80% by weight, preferably ≦ 75% by weight, very particularly preferably ≦ 70% by weight. As a result, in particular the advantageous properties of the present invention are achieved.

This is according to the invention Manufacturing process for the inner coating of the envelope glasses used not particularly limited, it Any coating method known to the person skilled in the art can be used become. For example, the coating by sputtering, Dipping the envelope glass, spray or baking the coating. For example, can the coating by immersion in a slurry with a powder, containing at least one of the designated dopants or consists of, carried out become.

To In another preferred embodiment of the invention, the above-described variants (1) and (2) not only individually, but also be used in combination. In this combined Variant becomes the envelope glass according to the invention the fluorescent lamp of the EEFL type, in its glass composition at least one of the dopants selected from the group (a) and / or (b) contains, additionally provided with a coating which at least one of said Dopants, selected from the group (a) and / or (b), contains or consists of. Especially preferred are combinations of two, three, four or more of designated dopants used.

The dopants used according to the invention lead in the glass composition and / or the coating of the glass to a significant reduction of the work function W _a for the electrons to a value <5 eV, preferably 0 eV <W _a <5 eV, particularly preferably 0 eV <W _a <4 eV, most preferably 0 eV <W _a <3 eV. Depending on the work function W _a can continue to set the so-called secondary emission rate γ. Accordingly, it is particularly preferred according to the invention if the envelope glasses and / or inner coating of the envelope glasses have a compound with a high secondary electron emission rate γ upon bombardment with ions, for example Hg, Xe, Ne and / or Ar ions. Preferably, by selecting the dopants in suitable amounts, the secondary electron emission rate γ is set such that: γ> 0.01, particularly preferably γ> 0.05, very particularly preferably γ> 0.1. By adjusting the secondary electron emission rate γ, it is possible to further optimize the envelope glasses according to the invention or their internal coatings for these envelope glasses for use in fluorescent lamps of the EEFL type, so that the desired low work function W _a for the electrons is obtained. This can be achieved, for example, by different combinations of the above-listed dopants and modification of the amounts used.

Especially preferred are glass compositions and / or coating materials in the present invention used that a big one have electronic density of states in the valence band. Most notably For example, coating materials with a high bandgap are preferred. for example> 4 eV to apply a coating also on a fluorescent dye enable.

From particular advantage has also for the operation of a fluorescent lamp of the EEFL type, when a gas mixture is used, Particularly preferred is a noble gas mixture of two or more noble gases with and without mercury vapor, for example gas mixtures with neon and / or Helium and / or argon and / or Hg and the like. Especially preferred are gas mixtures, the neon in the range of 10 to 99 vol.% contain and the rest in the form of other noble gases. The reason for the Use of gas mixtures is that a combination especially suitable properties arises. For example, Xenon has a lot good fluorescence properties while Neon because of its big Ionisierungsenergie leads to a large secondary emission rate γ, according to the invention in particular was recognized as advantageous.

The invention also relates to the use of a cladding glass or a (partial) internal coating for applications in which a low work function W _{a is} required, the low work function W _a for the electrons <5 eV, preferably 0 eV <W _a <5 eV, particularly preferably 0 eV <W _a <4 eV, very particularly preferably 0 eV <W _a <3 eV, in particular for EEFL-type fluorescent lamps, wherein the envelope glass or the (partial) inner coating comprises at least one of the described dopants in contains the appropriate amounts.

The use of the EEFL-type fluorescent lamp according to the invention, in particular of a miniaturized fluorescent lamp, is particularly in the field of backlight or backlight systems of electronic display devices or displays of all kinds, for example backlit displays in the case of active or passive or non-self-luminous displays (so-called "non Examples include computer monitors, in particular TFT devices, LCD displays, plasma displays, scanners, advertising signs, medical instruments, aerospace equipment, navigation technology, telephone displays, in particular Mobile phone displays, and in PDAs (Personal Digital Assis tant). For this application, such fluorescent lamps have very small dimensions and, accordingly, the lamp glass has only an extremely small thickness. Preferred displays and screens are so-called flat displays, used in laptops, especially flat backlight arrangements.

The structure, the arrangements and overall structures of the backlight systems in which the EEFL-type fluorescent lamps according to the invention can be used are not limited in accordance with the invention. Any conceivable backlight arrangement familiar to the person skilled in the art can be used. By way of example only, some backlight arrangements will be described below, to which the present invention is not limited, however:
For example, according to a first variant of a backlight arrangement, two or more fluorescent lamps can preferably be arranged parallel to one another and are preferably located between a base plate and a cover plate or substrate plate. Conveniently, one or more recesses are provided in the carrier plate in which the one or more bulbs are housed. Each well preferably contains a fluorescent lamp. The emitted light of the fluorescent lamp (s) is reflected on the display or screen.

advantageously, is on the reflective support plate according to this Variant, i. in particular in the one or more depressions, a reflection layer applied, that of the lamp in the direction of the carrier plate radiated light as a kind of reflector scatters evenly and thus for Homogeneous illumination of the display or screen ensures. As a substrate or cover plate or disc can any for this Purpose usual plates or discs are used, depending on the system design and purpose acts as a light distributor unit or merely as a cover. The substrate or cover plate or disk can therefore, for example a cloudy Diffuser disc or a clear transparent disc.

These Arrangement according to the first Variant is preferred for larger displays used, such as in televisions.

To a second variant for a possible one Backlight may also be the fluorescent lamp of the invention, for example outside be arranged the light distribution unit. So that or the bulbs for example outside be attached to a display or screen, in which case the light expediently by means of a light-transporting plate serving as a light guide, a so-called LGP (light guide plate), evenly across the display or the screen is decoupled. Such light-transporting plates have, for example a rough surface up, over the light is disconnected.

In a preferred embodiment of a third variant of a backlight system For example, the light-generating unit has an enclosed one Space on top through a preferably structured disc, below through a carrier disk as well as on the sides by walls is limited. For example, there are the fluorescent lamps, on the sides of the unit. This enclosed space can be transformed into individual radiation rooms be further divided, which contain a discharge phosphor can, for example, in a predetermined thickness on a carrier disk is applied. As a cover plate or disc can again, depending on System construction, a cloudy Diffuser disc or a clear transparent disc or the like be used.

The invention will be described below with reference to the attached 1 be described in more detail. It shows:

1 a preferred embodiment of a fluorescent lamp of the EEFL type according to the invention.

1 Fig. 12 is a schematic view of a preferred embodiment of an EEFL-type fluorescent lamp according to the present invention.

Here is an inventive, in particular miniaturized, fluorescent lamp 100 shown, which is constructed of a glass envelope 110 , a metal contact 120 which is provided, for example, in the form of an outer metal cap, and a discharge gas 130 located inside the EEFL-type fluorescent lamp 100 located. According to a particularly preferred embodiment is used as a discharge gas 130 a gas mixture used. Inside the sheath glass 110 thus practically creates a capacitor through which the electrical power is coupled as AC voltage. The sheath glass 110 not only serves as a dielectric in this capacitor, but the inner surface thereof also has the further function as a cathode material. An ion 140 from the discharge gas 130 migrates to the inner surface of the sheath glass 110 , which serves as a cathode material, and is neutralized there. According to the invention, the envelope glass 110 at least one dopant according to the invention and / or an inner coating (not shown) which contains or consists of at least one dopant according to the invention. As a result, due to the invention set low work function W _a for the electron of the outlet a secondary electron 150 induced. This can be done either from the envelope glass 110 itself or from one on the glass 110 applied coating (inner coating) or made of the coating and the glass envelope. Due to the doping of the sheath glass 110 and / or the inner coating becomes the probability of emitting secondary electrons 150 significantly enlarged when an ion 140 from the gas plasma 130 is neutralized at the surface of the cathode. This makes it possible to set the efficiency of a fluorescent lamp as large as possible. Further, a significantly lower ignition voltage of the EEFL-type fluorescent lamp results in comparison with known prior art EEFL-type fluorescent lamps.

According to the invention, therefore, an optimized EEFL-type fluorescent lamp is provided for the first time, whose cladding glass is doped either with a high alkaline earth ion concentration or an aluminum compound and / or has at least one of the specified heavy metal elements and / or with an inner coating containing or consisting of at least one of the mentioned Dopants, is provided. By providing at least one dopant in and / or on the inside surface of the glass envelope of a fluorescent lamp of the EEFL-type in an appropriate amount, it is possible due to the low work function W _a for electrons in the range <5 eV, particularly preferably in the range of 0 eV <W _a <4 eV, very particularly preferably 0 eV <W _a <3 eV to provide a high probability of leakage of secondary electrons. This is the first time that a tailor-made glass envelope has been made available for the optimal operation of a fluorescent lamp of the EEFL-TYP. In addition to setting the highest possible efficiency, it is also possible to set the ignition voltage of the lamp as low as possible. Due to a lower ignition voltage, for example, flat-panel monitors no longer need to use disadvantageous, particularly high voltages, as a result of which the safety risk can be significantly reduced. Furthermore, greater efficiency results because the dead times decrease significantly.

Claims (34)

EEFL-type fluorescent lamp for backlighting displays or displays comprising a cladding glass, wherein (1) the cladding glass has a low work function W _a for the electrons of <5 eV, preferably 0 eV <W _a <5 eV, particularly preferably 0 eV < W _a <4 eV, most preferably 0 eV <W _a <3 eV and contains at least one dopant selected from the group (a) consisting of BaO, CaO, MgO, SrO, MgF ₂ , AlN, Al ₂ O ₃ , and / or Mg _1-xy Sr _x Ca _y O, in an amount ranging from 3 to 70 wt .-%, particularly preferably from 5 to 60 wt .-%, most preferably from 10 to 60 wt. -%; and / or - from the group (b) consisting of La ₂ O ₃ , Bi ₂ O ₃ and / or PbO, in an amount in the range from 3 to 80% by weight, particularly preferably from 5 to 75% by weight. %, most preferably 10 to 65 wt .-%; and / or (2) the cladding glass has a (partial) inner coating which has a low work function W _a for the electrons of <5 eV, preferably 0 eV <W _a <5 eV, particularly preferably 0 eV <W _a <4 eV , very particularly preferably 0 eV <W _a <3 eV, the inner coating containing at least one dopant or consisting of at least one dopant selected from the group (a) consisting of BaO, CaO, MgO, SrO, MgF ₂ , AlN, Al ₂ O ₃ , and / or Mg _1-xy Sr _x Ca _y O, in an amount in the range of 3 to 70 wt .-%, particularly preferably from 5 to 60, wt .-%, most preferably of 10 to 60% by weight; and / or - from the group (b) consisting of La ₂ O ₃ , Bi ₂ O ₃ and / or PbO, in an amount in the range from 3 to 80% by weight, particularly preferably from 5 to 75% by weight. %., Most preferably 10 to 65 wt .-%. Fluorescent lamp of EEFL type according to claim 1, characterized characterized in that the sum of the existing amount of dopants from group (a) and group (b) in the glass envelope a lower limit of ≥ 15% by weight preferably ≥ 20 Wt .-%, most preferably ≥ 30 Wt .-% and an upper limit of ≤ 80 Wt .-%, preferably ≤ 75 Wt .-%, most preferably ≤ 70 % By weight. An EEFL-type fluorescent lamp according to claim 1 or 2, characterized in that the sum of the existing amount the dopants from group (a) and group (b) in the (partial) inner coating a lower limit of ≥ 15 % By weight preferably ≥ 20 Wt .-%, most preferably ≥ 30 Wt .-% and an upper limit of ≤ 80 Wt .-%, preferably ≤ 75 Wt .-%, most preferably ≤ 70 % By weight. Fluorescent lamp of the EEFL type after at least one of the preceding claims 1 to 3, characterized in that they have an optimized efficiency having. Fluorescent lamp of the EEFL type after at least one of the preceding claims 1 to 4, characterized in that the fluorescent lamp of the EEFL type has a low ignition voltage. Fluorescent lamp of the EEFL type after min according to one of the preceding claims, characterized in that the cladding glass and / or the inner coating contains one or more dopants selected from group (a) and / or (b) in an amount such that a high secondary electron emission rate γ> 0.01, particularly preferably γ> 0.05, very particularly preferably γ> 0.1. Fluorescent lamp of the EEFL type after at least one of the preceding claims, characterized in that the sheath glass and / or the inner coating a big have electronic density of states in the valence band. Fluorescent lamp of the EEFL type after at least one of the preceding claims, characterized in that the inner coating is a large bandgag, in particular> 4 eV, to provide a coating on a fluorescent dye enable. Fluorescent lamp of the EEFL type after at least one of the preceding claims, characterized in that the fluorescent lamp of the EEFL type a Contains gas mixture, which in particular has neon. Fluorescent lamp of the EEFL type after at least one of the preceding claims, characterized in that the gas mixture neon in one area from 10-99 % By volume. Fluorescent lamp of the EEFL type after at least one of the preceding claims, characterized in that the inner coating in a thickness from about 0.3 nm to about 10 μm is applied. EEFL fluorescent lamp envelope glass, wherein (1) the envelope glass has a low work function W _a for the electrons of <5 eV, preferably 0 eV <W _a <5 eV, particularly preferably 0 eV <W _a <4 eV, very particularly preferably 0 eV <W _a <3 eV and contains at least one dopant selected from the group (a) consisting of BaO, CaO, MgO, SrO, MgF ₂ , AlN, Al ₂ O ₃ , and / or Mg _1-xy Sr _x Ca _y O, in an amount ranging from 3 to 70% by weight, more preferably from 5 to 60% by weight, most preferably from 10 to 60% by weight; and / or - from the group (b) consisting of La ₂ O ₃ , Bi ₂ O ₃ and / or PbO, in an amount in the range from 3 to 80% by weight, particularly preferably from 5 to 75% by weight. %, most preferably 10 to 65 wt .-%; and / or (2) the cladding glass has a (partial) inner coating which has a low work function W _a for the electrons of <5 eV, preferably 0 eV <W _a <5 eV, particularly preferably 0 eV <W _a <4 eV , very particularly preferably 0 eV <W _a <3 eV, the inner coating containing at least one dopant or consisting of at least one dopant selected from the group (a) consisting of BaO, CaO, MgO, SrO, MgF ₂ , AlN, Al ₂ O ₃ , and / or Mg _1-xy Sr _x Ca _y O, in an amount in the range from 3 to 70 wt .-%, particularly preferably from 5 to 60 wt .-%, most preferably from 10 up to 60% by weight; and / or - from the group (b) consisting of La ₂ O ₃ , Bi ₂ O ₃ and / or PbO, in an amount in the range from 3 to 80% by weight, particularly preferably from 5 to 75% by weight. %., Most preferably 10 to 65 wt .-%. EEFL fluorescent lamp envelope glass according to claim 12, characterized in that the sum of the existing amount of Dopants from group (a) and group (b) in the envelope glass have a lower limit of ≥ 15% by weight preferably ≥ 20 Wt .-%, most preferably ≥ 30 Wt .-% and an upper limit of ≤ 80 % By weight, preferably ≦ 75% by weight, most preferably ≤ 70 % By weight. EEFL fluorescent lamp envelope glass according to claim 12, characterized in that the sum of the existing amount of Dopants from group (a) and group (b) in the (partial) internal coating a lower limit of ≥ 15 % By weight preferably ≥ 20 Wt .-%, most preferably ≥ 30 Wt .-% and an upper limit of ≤ 80 Wt .-%, preferably ≤ 75 Wt .-%, most preferably ≤ 70 % By weight. EEFL fluorescent lamp envelope glass after at least one of the preceding claims 12 to 14, characterized in that the enveloping glass and / or the coating one or more dopants selected from the group (a) and / or (b) in such an amount that a high secondary electron emission rate γ> 0.01, more preferably γ> 0.05, more particularly preferably γ> 0.1 is present. EEFL fluorescent lamp envelope glass after at least one of the preceding claims 12 to 15, characterized in that the sheath glass and / or the coating a big have electronic density of states in the valence band. EEFL fluorescent lamp envelope glass after at least one of the preceding claims 12 to 16, characterized in that the coating is a large bandgag, in particular> 4 eV, to provide a coating on a fluorescent dye enable. EEFL fluorescent lamp envelope glass after at least one of the preceding claims 12 to 17, characterized in that the inner coating in a thickness of about 0.3 nm to about 10 microns is applied. Producing a (partial) coating of the inner surface of the cladding glass of an EEFL-type fluorescent lamp according to at least one of the preceding claims 12 to 18, by sputtering, dipping, spraying or baking a coating material containing or consisting of at least one dopant selected from the Group (a) consisting of BaO, CaO, MgO, SrO, MgF ₂ , AlN, Al ₂ O ₃ , and / or Mg _1-xy Sr _x Ca _y O, in an amount ranging from 3 to 70% by weight. %, more preferably from 5 to 60 wt .-%, most preferably from 10 to 60 wt .-%; and / or - from the group (b) consisting of La ₂ O ₃ , Bi ₂ O ₃ and / or PbO, in an amount in the range from 3 to 80% by weight, particularly preferably from 5 to 75% by weight. %., Most preferably 10 to 65 wt .-%. Production according to claim 19, characterized that the coating by dipping a Schlemme with a Powder containing or consisting of one or more dopants from the group (a) and / or (b) is carried out. Production according to claim 19, characterized that the spraying the inside of the sheath glass with a slurry containing or consisting of a powder one or more dopants from the group (a) and / or (b) is performed. Using an EEFL-type fluorescent lamp according to at least one of the preceding claims 1 to 11, in particular a miniaturized fluorescent lamp, for backlight or Backlight systems of electronic display devices or displays all kinds. Use according to claim 22 for active or passive displays. Use according to claim 22 or 23 for computer monitors, especially TFT devices, LCD displays, Plasma displays, scanners, advertising signs, medical instruments, equipment aerospace, navigation technology, telephone displays, especially mobile phone displays, and in PDAs (Personal Digital Assistant). Use of a cladding glass for applications in which a low work function W _{a is} required, wherein the low work function W _a for the electrons <5 eV, preferably 0 eV <W _a <5 eV, particularly preferably 0 eV <W _a <4 eV, most preferably 0 eV <W _a <3 eV, in particular for fluorescent lamps of the EEFL type, wherein the cladding glass contains at least one dopant selected from the group (a) consisting of BaO, CaO, MgO, SrO, MgF ₂ , AlN, Al ₂ O ₃ , and / or Mg _1-xy Sr _x Ca _y O, in an amount ranging from 3 to 70 wt .-%, particularly preferably from 5 to 60 wt .-%, most preferably from 10 to 60% by weight; and / or - from the group (b) consisting of La ₂ O ₃ , Bi ₂ O ₃ and / or PbO, in an amount in the range from 3 to 80% by weight, particularly preferably from 5 to 75% by weight. %., Most preferably 10 to 65 wt .-%. Use of a cladding glass with a (partial) inner coating for applications in which a low work function W _{a is} required, wherein the low work function W _a for the electrons <5 eV, preferably 0 eV <W _a <5 eV, particularly preferably 0 eV <W _a <4 eV, very particularly preferably 0 eV <W _a <3 eV, in particular for fluorescent lamps of the EEFL type, wherein the (partial) inner coating contains at least one dopant or consists of at least one dopant selected from the Group (a) consisting of BaO, CaO, MgO, SrO, MgF ₂ , AlN, Al ₂ O ₃ , and / or Mg _1-xy Sr _x Ca _y O, in an amount ranging from 3 to 70% by weight. %, more preferably from 5 to 60 wt .-%, most preferably from 10 to 60 wt .-%; and / or - from the group (b) consisting of La ₂ O ₃ , Bi ₂ O ₃ and / or PbO, in an amount in the range from 3 to 80% by weight, particularly preferably from 5 to 75% by weight. %., Most preferably 10 to 65 wt .-%. Use according to claim 25, characterized that the sum of the existing amount of dopants from group (a) and group (b) in the cladding glass a lower limit of ≥ 15 % By weight preferably ≥ 20 Wt .-%, most preferably ≥ 30 Wt .-% and an upper limit of ≤ 80 Wt .-%, preferably ≤ 75 Wt .-%, most preferably ≤ 70 % By weight. Use according to claim 26, characterized that the sum of the existing amount of dopants from group (a) and group (b) in the (partial) inner coating a lower limit of ≥ 15 wt .-% preferably ≥ 20 Wt .-%, most preferably ≥ 30 Wt .-% and an upper limit of ≤ 80 Wt .-%, preferably ≤ 75 Wt .-%, most preferably ≤ 70 % By weight. Use according to at least one of the preceding claims 25 to 28, characterized in that the enveloping glass and / or the coating one or more dopants selected from the group (a) and / or (b) in such an amount that a high secondary electron emission rate γ> 0.01, more preferably γ> 0.05, more particularly preferably γ> 0.1 is present. Use according to at least one of the preceding claims 25 to 29, characterized in that the sheath glass and / or the coating a big have electronic density of states in the valence band. Use according to at least one of the preceding claims 25 to 30, characterized in that the inner coating a big bandgag, in particular> 4 eV, to provide a coating on a fluorescent dye enable. Use according to at least one of the preceding claims 25 to 31, characterized in that the inner coating in a thickness of about 0.3 nm to about 10 microns is applied. Sheath glass for applications in which a low work function W _{a is} required, wherein the low work function W _a for the electrons <5 eV, preferably 0 eV <W _a <5 eV, particularly preferably 0 eV <W _a <4 eV, especially preferably 0 eV <W _a <3 eV, in particular for EEFL-type fluorescent lamps, the cladding glass being produced by adding at least one dopant selected from group (a) consisting of BaO, CaO, MgO, SrO, MgF ₂ , AlN, Al ₂ O ₃ , and / or Mg _1-xy Sr _x Ca _y O, in an amount in the range of 3 to 70 wt .-%, particularly preferably from 5 to 60 wt .-%, most preferably from 10 to 60% by weight; and / or - from the group (b) consisting of La ₂ O ₃ , Bi ₂ O ₃ and / or PbO, in an amount in the range from 3 to 80% by weight, particularly preferably from 5 to 75% by weight. %, most preferably 10 to 65 wt .-%; to the starting material for the production of a cladding glass and producing the cladding glass. (Partial) inner coating for a cladding glass for applications in which a low work function W _{a is} required, wherein the low work function W _a for the electrons <5 eV, preferably 0 eV <W _a <5 eV, particularly preferably 0 eV <W _a <4 eV, most preferably 0 eV <W _a <3 eV, in particular for fluorescent lamps of the EEFL type, wherein the (partial) inner coating is prepared by adding at least one dopant selected from the group (a) of BaO, CaO, MgO, SrO, MgF ₂ , AlN, Al ₂ O ₃ , and / or Mg _1-xy Sr _x Ca _y O, in an amount in the range of 3 to 70% by weight, more preferably 5 to 60% by weight, most preferably from 10 to 60% by weight; and / or - from the group (b) consisting of La ₂ O ₃ , Bi ₂ O ₃ and / or PbO, in an amount in the range from 3 to 80% by weight, particularly preferably from 5 to 75% by weight. %, most preferably 10 to 65 wt .-%; to the starting material for the production of an inner coating and application to a glass envelope.