DE102006005611A1 - Glass for lamps with external electrodes has a low quotient of loss angle and dielectric constant - Google Patents

Abstract

Glass for lamps with external electrodes has a quotient of loss angle (tan delta ) and dielectric constant (epsilon') of less than 5 x 10 ->4>. An independent claim is also included for a lamp with a glass body comprising glass as above.

Description

The The invention relates to a backlit display comprising at least one lamp with external electrodes, such as For example, a fluorescent lamp, in particular an EEFL (external electrode fluorescent lamp).

Area Display ads are playing an increasingly important role. With one in the Usually white Backlight is a self-luminous display realized. This backlight is preferred with gas discharge lamps executed.

For backlighting in displays are very special requirements for the glass and its Properties provided. So should the used bulbs very small dimensions, accordingly have extremely small thickness and UV-absorbing properties, wherein the irradiated High frequency energy not or only slightly from the glass should be absorbed, for example, in the fluorescent lamp enclosed luminous gas for ignition bring to. This previously assumed that the glass is an extremely small imaginary the dielectric constant, one possible high real part of the dielectric constant or a very small one has dielectric loss angle tan δ. The dielectric loss angle serves as a measure of the Glass in the excited dielectric alternating field absorbed and in lost heat converted energy.

in the State of the art are fluorescent lamps with external electrodes (EEFLs) for Backlighting, for example, in applications KR1020030080915 A and KR1020020071685 A are described. But glasses are used their dielectric properties do not provide efficient gas discharge enable and the much too low dielectric strength (so-called "pinhole burning, "the one Breakdown at high voltages means) in the occurring Have voltages and temperatures.

The JP 2005093422 A2 and WO 2005/015606 A1 describe a container for Production of fluorescent lamps with external electrodes, wherein the glasses used relatively low dielectric power losses with a tan δ of not more than 0.02 at 40 kHz and 250 ° C exhibit.

JP 2002 338296 A2 and WO 02/072492 A1 disclose glasses having a high dielectric constant and a relatively low dielectric tan δ, but by the described high alkali contents with the sum of Li ₂ O, Na ₂ O and K ₂ O of 4.5 to 25% by weight, the dielectric loss is still too high for an efficient fluorescent lamp.

It There is therefore a need, a display with a highly efficient To develop lighting unit. The previously existing fluorescent lamps with external electrodes (EEFL) use glass tubes, which are especially in operation with AC voltages in the range between 10kHz and 100kHz yet a significant conductivity for electrical Have current. This is the overall efficiency of such a fluorescent lamp significantly impaired and the advantage of an EEFL for example, a CCFL (cold-cathode fluorescent lamp) intrinsic easy controllability and easier manufacturing, to one huge Part compensated by efficiency losses.

Therefore The present invention is based on the object, the disadvantages to avoid the prior art and a display with backlight provide the desired Requirements to a high degree Fulfills. In particular, this should illuminants with external electrodes, such as Fluorescent lamps available stand, which can be ignited by induction from outside and no by the enclosing Lens led through metal wires or need electrodes. This should be a glass available whose properties are modified and optimized in this way can be that possible low radiated high frequency energy is absorbed, i. the Total power loss of a lamp glass of a lamp with external Electrodes should be minimized. In addition, should the glass composition have good UV-absorbing properties.

bevorzugt < 4 × 10^–4 und < 3 × 10^–4, ganz besonders bevorzugt < 2 × 10^–4 und < 1,5 × 10^–4 beträgt. Eine ganz besonders bevorzugte Ausführung besitzt einen Quotienten aus

Insbesondere kann der Quotient auch auf < 0,7 × 10^–4 und < 0,5 × 10^–4 eingestellt werden.According to the invention, the object is achieved in the present invention by a display with a backlight, wherein the backlight is realized by means of bulbs with external electrodes, in particular highly efficient gas discharge tubes, which are powered by external electrodes with power. Here, a glass composition is used for a glass hollow body of the at least one luminous means with external electrodes, wherein the quotient of the loss angle and the dielectric constant

preferably <4 × 10 ^-4 and <3 × 10 ^-4 , very particularly preferably <2 × 10 ^-4 and <1.5 × 10 ^-4 . A most preferred embodiment has a quotient of

In particular, the quotient can also be set to <0.7 × 10 ^-4 and <0.5 × 10 ^-4 .

The values for tan δ can be given in values of 10 ^-4 ; this results then for the quotient

The values for tan δ can also be given as an absolute value; this results then for the quotient

As a numerical example, assume:
tan δ = 0.001 and tan δ [10 ^-4 ] = 10 and ε '= 4,
then the quotient

wobei gilt:

ω:

Kreisfrequenz

tan δ:

Verlustwinkel

ε':

Dielektrizitätszahl

d:

Dicke des Kondensators (hier: Dicke des Glases)

A:

Elektrodenfläche und

I:

Stromstärke

ε₀:

Influenzkonstante = 8.8542 10^–12 As/(Vm).

The invention thus relates to a display with backlight, wherein the glass is selected for the glass hollow body of the lamp with external electrodes such that the lowest possible power loss P _loss and thus the highest possible efficiency is obtained, the quotient of the loss angle tan δ and the Dielekrizitätszahl ε 'must not reach a certain upper limit. The gas discharge is ignited from the outside, the glass acting as a dielectric in a condenser. For a simple geometry with planar electrodes on the faces of a closed glass tube, the power dissipation (hereinafter referred to as P _loss or P _loss ) can be approximated by:

where:

ω:

angular frequency

Tan δ:

loss angle

ε ':

permittivity

d:

Thickness of the capacitor (here: thickness of the glass)

A:

Electrode surface and

I:

amperage

ε ₀ :

Influence constant = 8.8542 10 ^-12 As / (Vm).

Accordingly, by setting the quotient tan δ / ε 'in a certain range, specific influence is exerted on the glass properties, as a result of which the total power loss of the luminous means can be minimized. According to the invention it has surprisingly been found that the desired requirements can be achieved by using selected glass compositions as backlight for a display in a very cost-effective manner. Surprisingly, it turns out that glasses satisfying the above equation, according to which the quotient of the loss angle and the dielectric constant is below 5 × 10 ^-4 , are very well suited for applications in fluorescent lamps.

For using bulbs with external electrodes, such as an EEFL fluorescent lamp, for backlighting, the quotient is <5 × 10 ^-4 , preferably <4.5 × 10 ^-4 , particularly preferably <4.0 × 10 ^-4 , in particular <3 × 10 ^-4 , more preferably <2.5 × 10 ^-4 . Good properties are also achieved in the range of 0.75 × 10 ^-4 to 2.5 × 10 ^-4 . Very particular preference is furthermore given to a quotient <1.0 × 10 ^-4 , in particular <0.75 × 10 ^-4 .

Of the The quotient described above can be used for example in a glass composition of the glass hollow body, especially in silicate glasses, be set specifically by highly polarizable elements in oxidic form are incorporated into the glass matrix. These are e.g. the oxides of Ba, Hf, Ta, W, Re, Os, Ir, Pt, Pb, Bi, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.

According to the invention for the Hollow glassware of the light source in the display preferably glasses with a relatively high dielectric constant (dielectric constant DZ) used. there is the dielectric constant at 100 kHz at 25 ° C preferably> 3 and> 4, is in particular in the range of 3.5 to 4.5, more preferably> 5 and> 6, more particularly preferably> B. Particularly according to the invention be preferred for the Hollow glassware glasses with high polarizability, i. a dielectric constant ε '> 5, used.

Of the dielectric loss factor tan δ is preferred at most 120 and preferably less than 100. Particularly preferred Loss factors are below 80, with values below 50 and below 30 are particularly suitable. Most preferred are values below 15, in particular a range between 1 and 15. Depending on the degree of Contamination and the manufacturing process, tan δ values may vary. However, what is decisive is not the individual values of loss angle Tan δ and the Dielekrizitätszahl ε 'independently possible set low, but the two values related to each other to put. Indeed the quotient of both parameters represents the critical size by means of which the adjustment of the glass material properties succeeds.

wobei die Anwendungsfrequenzen im Bereich von 5-200 kHz, bevorzugt 10-150 kHz, besonders bevorzugt 20-100 kHz liegen.Preferably, in the display according to the invention for the glass hollow body of the luminous means with external electrodes, such as EEFLs, a glass is selected, for which the following applies:

wherein the application frequencies are in the range of 5-200 kHz, preferably 10-150 kHz, more preferably 20-100 kHz.

Around To adjust such frequencies are preferably according to the invention Means for controlling the bulbs with external electrodes, in particular EEFL (s), with AC voltages present, preferably AC voltages in the range of 0.5-10kV, more preferably 0.8-6kV in the frequency domain of 5-200 kHz, preferably 10-150kHz, more preferably 20-100kHz provided are (i.e., outside of the frequencies that when they resonantly vibrate mechanically in the Stimulate system, are audible). These means for controlling the lighting means are for example for sinusoidal signals designed, but preferred are rectangular signals. Especially preferred the means represent an electronic control unit, which the desired Generates voltages and signal forms. It can still be beneficial be when the electronic drive unit with a current limit is provided.

According to a further preferred embodiment, glasses with low conductivity are selected for the glass hollow body of the luminous means, in particular those with tan δ <20 × 10 ^-4 , particularly preferably tan δ <1 × 10 ^-4 . Most preferably, the glass compositions contain only a low concentration of alkali ions, in particular, the sum of Li ₂ O, Na ₂ O and K ₂ O is below, preferably well below 4.5 wt .-%.

Farther are particularly preferred for the glass hollow body glasses used, whose UV blocking was adjusted as desired. So can the UV blocking in the glasses for example by incorporation of rare earth or transition metal ions, be set in the glass compositions. Come for this For example, the following elements in question: Ti, Ce, W, Nb, Bi, Yb, Fe and / or Ni.

However, the UV blocking can also be set in the form of an inner or outer coating of the glass hollow body, in particular suitable is an inner or outer coating of TiO ₂ .

A other variant of the invention concerns a possible Inner coating of the glass hollow body for converting light from UV or blue light to white light in total with a fluorescent layer of a solid powder containing rare earth ions is doped. This is, for example, a YAG powder doped with for example, Ce, Eu, Tm, Tb, Dy and / or Gd.

It but can also be a doping of glasses for light conversion of UV or blue light in total white light due to fluorescent Rare earth ions and / or transition metal ions be provided. For example, rare earth ions are selected from Ce, Eu, Tm, Tb, Dy, and / or Gd.

When the one or more used according to the invention Illuminant with external Electrodes may be any illuminant known to those skilled in the art for this purpose be used. Preferably, the light source is external Electrodes a discharge lamp, such as a gas discharge lamp, in particular a low-pressure discharge lamp. For low pressure lamps, the discrete UV lines partially converted into visible through fluorescent layers. Therefore, the lamp can also be a fluorescent lamp, in particular an EEFL lamp, most preferably a miniaturized fluorescent lamp be.

The cross section of the light source is arbitrary and adapted to the spatial conditions of the display. Round, oval, rectangular and / or flat rectangular cross-section (for example Planon ^® from Osram) are preferred. The bulbs can all have the same cross-section or different cross-sectional shapes can be combined. It is very particularly preferable to provide as background illumination for the display according to the invention one or more light sources with external electrodes, for example EEFLs, which have a flat rectangular cross-section.

Under "display" is inventively every electronic Display device understood; Below are also screens fall of all kinds.

The Size of the invention used Displays are not particularly limited within the scope of the invention. Preferably come display sizes in the range from 50 × 50 mm to 4 × 5 m for use.

It is any display known in the art in the present invention usable. For example, you can these are displays that have a preferably structured glass pane, a liquid crystal layer, polarization units as well as another glass pane for include the display.

Usually contains a display a light distribution unit. This is under the Invention not particularly limited. For example, a diffuser or a diffuser plate or disk or a photoconductive or transporting plate or disc, like a LGP ("light guide plate "), use Find. However, the light distribution unit preferably comprises according to the invention a polymer with scattering centers, glass, phase-separated glass or Glass ceramic. Particularly preferred are inhomogeneously distributed scattering centers for optimal homogeneous light distribution available. So inhomogeneous distributed scattering centers can for example, with a glass ceramic in the temperature gradient crystallized.

To a further embodiment the invention, the light distribution unit has a structured surface or defined surface roughness with rms values in the order of magnitude the wavelength of light on, preferably with 20 nm <rms <100,000 nm, especially preferably 10 nm <rms <10000 nm. The rms values mean the standard deviation of the surface of an average.

The in the display according to the invention existing light distribution unit can also be designed as a hollow body its walls by reflecting the light, and by the surface roughness the light is disconnected.

• a) Metall oder Metallblech, zum Beispiel aus Cu, Al, Ag und dergleichen
• b) Tauchbeschichtungen aus Metall oder metallhaltigen leitenden Substanzen,
• c) Leitlack, wie beispielsweise silberhaltiger Leitlack, oder
• d) leitendem Klebeband, wie ein Metallklebeband.

The material of the contacts on the glass hollow body is not particularly limited; these may preferably be selected from

• a) metal or metal sheet, for example of Cu, Al, Ag and the like
• b) dip coatings of metal or metal-containing conductive substances,
• c) conductive ink, such as silver-containing conductive ink, or
• d) conductive adhesive tape, such as a metal tape.

Farther can for thermal management at the light source, in particular for the passive cooling of cooling plates be provided. For active cooling it is usual, to provide a fan and / or liquid cooling.

The structure and the arrangement of the light source and the light distribution unit are not particularly limited in the display according to the invention. Some variants according to the invention are described below, to which, however, the teaching according to the invention should not be restricted:
According to a first variant of the invention, at least two bulbs with external Electrodes are preferably arranged parallel to one another and are preferably located between base plate and carrier plate and cover or substrate plate or plate. Conveniently, in this case one or more recesses or cavities are provided in the carrier plate, in which the one or more bulbs are housed. Each recess preferably contains a lighting means. The emitted light of the 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 to the bulb from the direction of the support plate radiated light as a kind of reflector scatters evenly and thus for Homogeneous illumination of the display or screen ensures.

When Substrate or cover plate or disc may be any for this Purpose usual Plates or discs are used, depending on the system design and application as a light distribution unit or merely as Cover act. The substrate or cover plate or disk Thus, for example, a cloudy diffuser disc or a be clear transparent disc.

These Arrangement according to the first variant according to the invention is preferred for used larger displays, like TV sets.

To According to a second variant of the invention, the lighting means can accordingly the display according to the invention for example, outside be arranged the light distribution unit. That's how it can be or the bulbs, for example, on the outside of a display or screen be attached, in which case the light expediently by means of a Optical fiber serving light transporting plate, a so-called. LGP (light guide plate), evenly over the Display or the screen is disconnected. Such light-transporting plates For example, have a rough surface, coupled out via the light becomes.

To A third variant of the display according to the invention can also be electrodeless lamp system, i. a so-called EEFL system (external electrode fluorescent lamp) are used. Concerning EEFL lamps are referred to: Cho G. et al., J. Phys. D: Appl. Phys. Vol. 37, (2004), pp. 2863-2867 and Cho T.S. et al., Jpn. J. Appl. Phys. Bd. 41, (2002), pp. 7518-7521, their revelation content in full is included in the present disclosure.

In a preferred embodiment of this invention third Variant of the invention, the light-generating unit, for example an enclosed space, the above by a preferably structured disc, below through a carrier disc and on the sides through walls is limited. For example, the bulbs, such as Fluorescent lamps, on the sides of the unit. This enclosed For example, room can be further subdivided into individual radiation rooms which may contain a discharge phosphor which 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.

A backlight according to the invention according to this variant, for example, an electrodeless gas discharge lamp, d. H. there are no executions, but only external or external Electrodes.

Of the Hollow glassware the bulb with external Contains electrodes preferably a filling of a gas selected from Hg gas, noble gas, in particular Xe gas or mixtures thereof.

If in the display according to the invention used bulbs represents a high pressure lamp, the pressurized filling gases come to such high temperatures that a continuous spectrum arises or, if Hg and / or Xe gas is contained as a filling gas, a additional strong broadening of the Hg and / or Xe line spectrum is present, the above external electrodes can be controlled.

The Glass of the glass hollow body of the bulb contains or consists of a glass composition which meets the above requirement to the quotient of the loss angle tan δ and the Dielekrizitätszahl ε 'met. Prefers are one or more individual, especially miniaturized bulbs used, the glass hollow body such glasses essentially contains or consists of these.

die Σ Al₂O₃ + B₂O₃+ BaO + PbO + Bi₂O₃ 10–80 Gew.-% beträgt,
wobei Hf, Ta, W, Re, Os, Ir, Pt, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb und/oder Lu in oxidischer Form in Gehalten von 0–80 Gew.-% vorliegen, sowie Läutermittel in üblichen Konzentrationen.In the display according to the invention, the glass of the glass hollow body for a lamp with außenlie As electrodes, such as an EEFL discharge lamp, therefore, preferably the following composition:

ΣAl ₂ O ₃ + B ₂ O ₃ + BaO + PbO + Bi ₂ O _{3 is} 10-80% by weight,
where Hf, Ta, W, Re, Os, Ir, Pt, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and / or Lu in oxidic form in contents of 0- 80 wt .-% present, as well as refining agent in conventional concentrations.

die Σ Al₂O₃ + B₂O₃ + BaO + PbO + Bi₂O₃ 10–80 Gew.-% beträgt,
sowie Läutermittel in üblichen Konzentrationen.A further particularly preferred embodiment of the glass composition according to the invention is:

ΣAl ₂ O ₃ + B ₂ O ₃ + BaO + PbO + Bi ₂ O _{3 is} 10-80% by weight,
as well as refining agents in usual concentrations.

Especially Preferably, the glass is free up to unavoidable impurities of alkalis.

Accordingly, borosilicate glasses are particularly preferably used for the glass hollow body of the lamps in the displays according to the invention. Borosilicate glasses include as the first component SiO ₂ and B ₂ O ₃ and as further component alkaline earth, such as CaO, MgO, SrO and BaO and optionally alkali metal oxide, such as Li ₂ O, Na ₂ O and K ₂ O.

Borosilicate glasses with a content of B ₂ O ₃ between 5 and 15 wt .-% show a high chemical resistance. Borosilicate glasses with a content of B ₂ O ₃ between 15 and 25 wt .-% show good processability. Borosilicate glasses with a B ₂ O ₃ content in the range of 25-35 wt .-% show when using as a lamp glass a particularly low dielectric loss factor tan δ, whereby these are particularly advantageous for use according to the invention in lamps whose electrodes are mounted outside the lamp envelope, such as electrodeless gas discharge lamps.

According to one embodiment of the invention, the base glass usually contains preferably at least 30 wt .-% or at least 40 wt .-% SiO ₂ , wherein at least 50 wt .-% and preferably at least 55 wt .-% are particularly preferred. A most preferred minimum amount of SiO ₂ is 57% by weight. The maximum amount of SiO ₂ is 85 wt .-%, in particular 75 wt .-%, with 73 wt .-% and in particular at most 70 wt .-% SiO _{2 are} very particularly preferred. Furthermore, very particularly preferred are the ranges of 50-70 wt .-% and 55-65 wt .-%. Glasses with a very high SiO ₂ content are characterized by a low dielectric loss factor tan δ and are therefore suitable for the luminous means used according to the invention with external electrodes, such as electrodeless fluorescent lamps, taking account of the quotient tan δ / ε '.

B ₂ O ₃ is according to the invention in an amount of more than 0 wt .-%, preferably more than 0.2 wt .-%, preferably more than 2 wt.% Or 4 wt .-% or 5 wt .-% and in particular at least 10 wt .-% or at least 15 wt .-%, with at least 16 wt .-% are particularly preferred. The maximum amount of B ₂ O ₃ is at most 35 wt .-%, but preferably at most 32 wt .-%, with a maximum of 30 wt .-% are particularly preferred.

Although the glasses used in the hollow glass body may in some cases also be free of Al ₂ O ₃ , they usually contain Al ₂ O ₃ in a minimum amount of 0.1, in particular 0.2 wt .-%. A minimum content of 0.3 is preferred, with minimum amounts of 0.7, in particular at least 1.0% by weight being particularly preferred. The maximum amount of Al ₂ O ₃ is 25 wt .-%, with a maximum of 20 wt .-%, in particular 15 wt .-% are preferred. Very particular preference is given to ranges from 14 to 17% by weight. In some cases, a maximum amount of 8% by weight, in particular 5% by weight, has proven sufficient.

The sum of the alkali oxides is preferably <5 wt .-%, preferably <1 wt .-%. Most preferably, the glass composition is free of alkali, except for unavoidable impurities. Li ₂ O is preferably in an amount of 0-5, in particular <1.0 wt .-%, Na ₂ O is preferably in an amount of 0-3, in particular <3.0 wt .-%, and K ₂ O. is preferably used in an amount of 0-9, in particular <5.0 wt .-%, wherein a minimum amount of each ≤ 0.1% by weight, or ≤ 0.2 and in particular ≤ 0.5 wt. -% is preferred.

The Alkaline earth oxides Mg, Ca and Sr according to the invention are each in an amount of 0-20% by weight and in particular in an amount of 0-8 wt.% or 0-5 wt.% contain. The content of the individual alkaline earth oxides is maximum for CaO 20% by weight; in individual cases However, maximum contents of 18, in particular not more than 15 wt .-% sufficient. In several cases a maximum level of 12% by weight has proven sufficient. Although the glass of the invention may also be free of calcium constituents, the glass according to the invention contains but usually at least 1% by weight of CaO, with contents of at least 2% by weight, in particular at least 3 wt .-% are preferred. In practice has a minimum content of 4 wt .-% proved to be useful. The lower limit for MgO is in individual cases 0 wt .-%, but at least 1 wt .-% and preferably at least 2 wt .-% are preferred. The maximum salary of MgO in the glass 8 wt .-%, with a maximum of 7 and especially a maximum of 6 wt .-% preferred are. SrO can be completely in the glass accounts; however, it is preferably in an amount of 1% by weight, in particular contain at least 2 wt .-%.

Around the quotient of tan δ and ε 'according to the invention as possible small, contains the glass composition of the glass hollow body highly polarizable elements in oxidic form, incorporated into the glass matrix. Such hochpolarisierbare Elements in oxidic form can selected be from the group consisting of the oxides of Ba, Cs, Hf, Ta, W, Re, Os, Ir, Pt, Pb, Bi, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, He, Tm, Yb and / or Lu.

Prefers At least one of these oxides is contained in the glass composition. It can also mixtures of two or more of these oxides are present. At least one of these oxides is therefore preferably in an amount of> 0 to 80 wt .-%, preferably from 5 to 75 wt .-%, particularly preferably 10 to 70 wt .-%, in particular Contain 15 to 65 wt .-%. Further preferred are 15 to 60 wt .-%, 20 to 55 or 20 to 50 wt .-%. Even more preferred are 20 to 45 Wt .-%, in particular 20 to 40 wt .-% or 20 to 35 wt .-%. Especially preferably 15, in particular 18, preferably 20 wt .-% not below.

Cs ₂ O, BaO, PbO, Bi ₂ O ₃ and the rare earth metal oxides lanthanum oxide, gadolinium oxide, ytterbium oxide are particularly preferably present in the glass composition of the glass hollow body.

Especially preferably at least 15% by weight, more preferably 18% by weight, in particular 20% by weight, very particularly preferably more than 25% by weight of one or more of the highly polarizable elements in oxide form contained in the glass composition.

The content of CeO ₂ is preferably 0-5 wt .-%, with amounts of 0-1 and in particular 0-0.5 wt .-% are preferred. The content of Nd ₂ O ₃ is preferably 0-5 wt .-%, with amounts of 0-2, in particular 0-1 wt .-% are particularly preferred. Bi ₂ O _{3 is} particularly preferably present in an amount of 0-80% by weight, preferably from 5 to 75% by weight, particularly preferably 10 to 70% by weight, in particular 15 to 65% by weight. Further preferred are 15 to 60 wt .-%, 20 to 55 or 20 to 50 wt .-%. More preferred are 20 to 45% by weight, especially 20 to 40% by weight or 20 to 35% by weight.

By the addition of at least one of these polarizable oxides in the above surprisingly high levels can therefore be targeted to the glass properties in the Way, be influenced, so that the total power loss compared to usual in bulbs for Displays used glasses can be significantly reduced and reduced to a minimum.

The Sum of all Alkaline earth oxides according to the invention thus preferably 0-80% by weight, especially 5-75 Wt .-%, preferably 10-70 Wt .-%, more preferably 20-60 Wt .-%, most preferably 20-55 wt .-%. Further preferred are 20-40 Wt .-%.

The glass of the glass hollow body may be free of ZnO, but preferably contains a minimum amount of 0.1 wt .-% and a maximum content of at most 15 wt .-%, with maximum levels of 6 wt .-% and 3 wt .-% well may still be useful. ZrO ₂ is contained in an amount of 0-5 wt .-%, in particular 0-3 wt .-%, with a maximum level of 3 wt .-% has proven in many cases to be sufficient. In addition, WO ₃ and MoO _{3 may be contained} independently of one another in each case in an amount of 0-5% by weight or 0-3% by weight, but in particular of 0.1-3% by weight.

It has proved to be particularly preferable according to the invention if the sum of Al ₂ O ₃ + B ₂ O ₃ + Cs ₂ O + BaO + Bi ₂ O ₃ + PbO is in the range from 15 to 80% by weight, preferably from 15 to 75 Wt .-%, in particular 20 to 70 wt .-% is. Since B ₂ O _{3 is} usually used with a maximum amount of 35% by weight, the remaining 45% by weight is distributed over one or more of the polarizable oxides BaO, Bi ₂ O ₃ , Cs ₂ O and PbO.

To a preferred embodiment the PbO content is advantageously 0 to 70 wt .-%, preferably 10-65 Wt%, more preferably 15-60 % By weight. Particularly preferred are 20 to 58 wt .-%, 25th to 55 wt .-%, in particular 35 to 50 wt .-%, included.

erfüllt werden. Wenn die erfindungsgemäßen Gläser kein PbO enthalten, sind diese erfindungsgemäß bevorzugt frei von Alkali.According to a particular embodiment, if the PbO content is above 50% by weight, in particular if it is above 60% by weight, the glass may contain alkalis in a content of more than 3% by weight, in particular more than 4% by weight. , or over 5 wt .-% may be added, wherein not more than 10 wt.% Should be included, while still the requirement for the quotient

be fulfilled. If the glasses according to the invention contain no PbO, they are preferably free of alkali according to the invention.

The glasses may also contain TiO ₂ to adjust the "UV edge" (absorption of UV radiation), although in principle they may also be free thereof The maximum content of TiO ₂ is preferably 10% by weight, in particular not more than 8% by weight. A preferred minimum content of TiO ₂ is 1% by weight. Preferably at least 80% to 99%, in particular 99.9 or 99.99%, of the TiO _{2 contained is present} as Ti ⁴⁺ before. in some cases, Ti ⁴⁺ have proven -contents of 99.999% as meaningful, wherein the melt is preferably under oxidative conditions is generated. oxidative conditions, therefore especially understood to mean those in which titanium as in the above-stated amount of Ti ⁴⁺ or oxidized to this stage.These oxidative conditions can be easily achieved in the melt, for example, by adding nitrates, in particular alkali nitrates and / or alkaline earth metal nitrates Off and / or dry air, an oxidative melt can be achieved. Except it is possible, an oxidative melt by means of an oxidizing burner setting, z. B. when melting the batch to produce.

If the TiO ₂ contents of the glass composition are> 2% by weight and a mixture with a total Fe ₂ O ₃ content of> 5 ppm is used, preference is given to purifying with As ₂ O ₃ and melting it with nitrate. The addition of nitrate is preferably carried out as alkali nitrate with contents> 1 wt .-%, in order to suppress a coloration of the glass in the visible range (the formation of the ilmenite (FeTiO ₃ ) mixed oxide). Furthermore, a refining with Sb ₂ O ₃ and nitrate is possible.

Even though nitrate, preferably in the form of alkali and / or alkaline-earth nitrates, during glass melting, is added is the nitrate concentration in the finished glass after refining only a maximum of 0.01 wt .-% and in many cases the highest 0.001 wt .-%.

The content of Fe ₂ O ₃ is preferably 0-5 wt .-%, with amounts of 0-1 and in particular 0-0.5 wt .-% are preferred. The content of MnO ₂ is 0-5 wt .-%, with amounts of 0-2, in particular 0-1 wt .-% are preferred. The constituent MoO ₃ is contained in an amount of 0-5 wt.%, Preferably 0-4 wt.%, And As ₂ O ₃ and / or Sb ₂ O ₃ are each in the glass according to the invention in an amount of 0- 1 wt .-%, wherein the subset of the minimum contents is preferably 0.1, in particular 0.2 wt .-%. The glass according to the invention optionally contains small amounts of SO ₄ ^2- from 0-2 wt .-%, and Cl ^- and / or F ^- also in an amount of 0-2 wt .-% in a preferred embodiment.

Fe ₂ O ₃ can be added to the glass in an amount of up to 1% by weight. However, the contents are preferably much lower. If iron is contained, it is converted by the oxidizing conditions during the melt, for example by using nitrate-containing raw materials in its oxidation state +3, whereby the discoloration in the visible wavelength range are minimized. Fe ₂ O ₃ is preferably contained in the glass in contents <500 ppm. Fe ₂ O ₃ is generally present as an impurity.

In particular, a discoloration of the glasses, in particular with the addition of TiO ₂ in contents of> 1 wt .-% in the visible wavelength range can be at least partially avoided by the glass melt is substantially free of chloride and in particular no chloride and / or Sb ₂ O ₃ is added for refining the glass melt. It has been found that a blue color of the glass, as occurs in particular when using TiO ₂ , can be avoided if chloride is omitted as refining agent. The maximum content of chloride and fluoride according to the invention is 2, in particular 1 wt .-%, wherein contents of max. 0.1 wt .-% are preferred.

Of Further, it has been shown that sulfates, such as. B. as refining be used, as well as the aforementioned means to one discoloration of the glass in the visible wavelength range to lead. It is therefore preferred to dispense with sulfates. The maximum salary of sulfate 2% by weight according to the invention, in particular 1 wt .-%, wherein contents of max. 0.1 wt .-% preferred are. As a visible wavelength range In the present patent, the wavelength range between 380 nm and 780 nm understood.

In addition, it was found for the glasses that the disadvantages described above can be further avoided if a refining with As ₂ O ₃ is carried out under oxidizing conditions. The glass preferably contains 0.01-1% by weight of As ₂ O ₃ .

It has been found that, although the glasses are very stable against solarization under UV irradiation, the solarization stability is due to low levels of PdO, PtO ₃ , PtO ₂ , PtO, RhO ₂ , Rh ₂ O ₃ , IrO ₂ and / or Ir ₂ O ₃ can be further increased. The usual maximum content of such substances is at most 0.1% by weight, preferably at most 0.01% by weight, with a maximum of 0.001% by weight being particularly preferred. The minimum content for these purposes is usually 0.01 ppm, with at least 0.05 ppm and in particular at least 0.1 ppm being preferred.

die Σ Al₂O₃ + B₂O₃ + BaO + PbO + Bi₂O₃ 8–65 Gew.-% beträgt,
wobei Hf, Ta, W, Re, Os, Ir, Pt, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb und/oder Lu in oxidischer Form in Gehalten von 0–80 Gew.-% vorliegen, sowie Läutermittel in üblichen Konzentrationen.The above-mentioned glass compositions are designed for lamps with external electrodes, in which there is no melting of the glass with electrode feedthroughs, such as EEFL lamps without electrode feedthroughs. Since in an electrodeless EEFL backlight the coupling takes place by means of electric fields, the glass compositions described below are also particularly suitable, which are characterized by a corresponding quotient of the loss factor and the dielectric constant in the range according to the invention:

Σ Al ₂ O ₃ + B ₂ O ₃ + BaO + PbO + Bi ₂ O _{3 is} 8-65% by weight,
where Hf, Ta, W, Re, Os, Ir, Pt, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and / or Lu in oxidic form in contents of 0- 80 wt .-% present, as well as refining agent in conventional concentrations.

die Σ Al₂O₃ + B₂O₃ + BaO + PbO + Bi₂O₃ 10–80 Gew.-% beträgt,
wobei Hf, Ta, W, Re, Os, Ir, Pt, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb und/oder Lu in oxidischer Form in Gehalten von 0–80 Gew.-% vorliegen, sowie Läutermittel in üblichen Konzentrationen.Furthermore, the following glass compositions are also preferred:

ΣAl ₂ O ₃ + B ₂ O ₃ + BaO + PbO + Bi ₂ O _{3 is} 10-80% by weight,
where Hf, Ta, W, Re, Os, Ir, Pt, La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and / or Lu in oxidic form in contents of 0- 80 wt .-% present, as well as refining agent in conventional concentrations.

All of the aforementioned glass compositions preferably contain the previously indicated amounts of Fe ₂ O ₃ and are very particularly preferably substantially free of Fe ₂ O ₃ .

According to a further preferred embodiment, the glass composition according to the invention is composed of SiO ₂ with and without dopants. In the context of the invention, doping means doping oxides, in particular the oxides which have been mentioned in detail with the respective quantities.

A preferred compositional range of the glass compositions for the glass hollow body of this embodiment of the invention is:

This results in the upper limit of the SiO ₂ content by 100 wt .-% - all lower limits of the existing doping oxides, ie the sum of all lower limits is subtracted, for example, if the content of TiO ₂ 5-10 wt .-% is and the content CeO ₂ 2-5 wt .-%. is, the upper limit is calculated for SiO ₂ with: 100 - (5 + 2) = 93% by weight. Very particular preference is given to pure SiO ₂ without doping.

The maximum content of TiO ₂ , in particular for UV blocking of the glass, is 10% by weight, with preferably not more than 8% by weight, in particular not more than 5% by weight, and also contents of between 1 and 4% by weight. possible are. The CeO ₂ content is at most 5 wt .-%, wherein also amounts of 0 to 4 wt .-%, in particular 0 to 3 wt .-%, more preferably below 1 wt .-% can be adjusted. Other oxides already described may also be included.

Processes for the production of SiO ₂ glasses, in particular of amorphous SiO ₂ (silica glass, quartz glass) are, for example: vapor deposition, leaching of borosilicate glass and subsequent sintering and production of a glass melt.

The described glasses of the invention are suitable, with the exception of the abovementioned SiO ₂ glasses, in particular for the production of flat glass, in particular by the float process. In addition, the glasses are suitable for the production of tubular glass, the Danner method being particularly preferred. However, the production of tube glass is also possible by the bicycle or A-train method. It is particularly suitable for the production of tubes with a diameter of at least 0.5 mm, in particular at least 1 mm and an upper limit of at most 2 cm, in particular at most 1 cm. Particularly preferred tube diameters are between 2 mm and 5 mm. It has been found that such tubes have a wall thickness of at least 0.05 mm, in particular at least 0.1 mm, with at least 0.2 mm being particularly preferred. Maximum wall thicknesses are at most 1 mm, with wall thicknesses of at most <0.8 mm or <0.7 mm being preferred.

The Glass of light bulb with outboard Contains electrodes a glass composition or consists of this, beyond that also has a UV-blocking effect to the desired extent.

It has been found that the described glasses, in particular borosilicate glasses or pure or doped SiO ₂ , are particularly suitable for the production of lamp glasses for lamps with external electrodes for displays, since these satisfy the above requirement for the quotient of the loss angle tan δ and the Dielekrizitätszahl ε'e fulfill. The glasses described are used for backlighting the displays according to the invention, for example in LCD displays or screens, as well as back-lit displays (passive displays, so-called displays with a backlight unit) as a light source, such as in computer monitors, in particular TFT devices, as well as scanners, advertising signs, medical instruments and aerospace equipment, as well as navigation technology, mobile phones and PDAs (Personal Digital Assistant). 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 Invention will be described below with reference to the drawings become.

It demonstrate:

1 a schematic representation of a display according to the invention with a miniaturized backlight arrangement;

2 a schematic representation of a display according to the invention with a backlight arrangement with external electrodes;

3 a schematic representation of a display according to the invention with side-mounted fluorescent lights;

4 a schematic representation of a display according to the invention with EEFL lamps;

5 a schematic representation of exemplary cross sections of lamps used in the invention;

6 a schematic representation of a lamp assembly, which was used for the measurements in the following examples;

7 an electrical equivalent circuit diagram (RC element) of the representation of the lamp according to 4 and

8th a representation of a sinusoidal and rectangular, periodic voltage.

In the 1 to 3 the use of backlight lamps in a display according to the invention is shown by way of example, whose hollow glass body contains or consists of a suitable glass composition.

In 1 is shown a special use for such applications where individual miniaturized fluorescent tubes 110 , consisting of suitable glasses, used in parallel and extending in a plate 130 with depressions 150 located, which reflect the emitted light on the display according to the invention. Above the reflective plate 130 is a reflection layer 160 Applied to the fluorescent tube 110 in the direction of the plate 130 radiated light as a kind of reflector evenly and thus ensures a homogeneous illumination of the display. This arrangement is preferably used for larger displays such. B. in televisions.

According to the embodiment in FIG 2 can the fluorescent tube 210 also outside on the display 202 be attached, in which case the light by means of serving as a light guide light transporting plate 250 , a so-called LGP (light guide plate), is decoupled evenly across the display.

Moreover, it is also possible to use such backlight arrangements in which the light-generating unit 310 directly in a structured disk 315 located. This is in 3 shown. The structuring is such that by means of parallel elevations, so-called barriers 380 with a predetermined width (W _rib ), in the disc channels of predetermined depth and predetermined width (d _channel or W _channel ) are generated, in which the discharge phosphor 350 located. The channels form together with a disk, which with a phosphor layer 370 is provided, several radiation cavities 360 , In the 3 Backlight arrangement shown is an electrodeless gas discharge lamp, ie there are no feedthroughs, but only external electrodes 330a . 330b , In the 3 Shroud shown 410 may be a cloudy diffuser or a clear transparent glass depending on the system design. At the in 3 The electrodeless lamp system shown is called a so-called EEFL system (external electrode fluorescent lamp). The arrangements described above form a large, flat backlight and are therefore also referred to as Flachbacklight.

4 shows a schematic representation of a display according to the invention with lighting means with external electrodes, such as EEFLs. Shown is a display, such as an LCD display 1 , for example, each with a glass cover on the top and bottom. Further, a liquid crystal layer with polarizers 2 shown. In the molds are in 4 Fluorescent gas discharge lamps, 3 , which in the present case are round tubes made of special glass 6 are included. Of course, other cross sections can be used. About the bottom 5 The display dissipates heat. The light distribution unit is with 4 designated.

5 shows schematic representations of exemplary cross sections of bulbs. For example, geometries with round, oval, rounded or rectangular cross sections are shown.

In 6 is shown in schematic form part of a lamp, in particular an EEFL glass tube, on which the measurements were carried out in the following examples, the results of which were summarized in Table 9. 6 shows in schematic form one end of a glass tube 1000 , The glass tube 1000 comprises a glass of thickness d, wherein the diameter of the glass tube is 2r. The electrode is with 1010 denotes and extends over a length l on the outside of the tube 1000 ,

In 7 is the electrical equivalent circuit (RC element) of the lamp assembly according to the 6 shown.

wobei der letzte Faktor G nur den Effekt der Geometrie beeinhaltet, ε₀ = (μ₀c²)^–1 = 8,85418710^–12AsV^–1m^–1 ist die Influenzkonstante und ε' ist der reelle Teil der Dielektrizitätskonstante. Die von der Frequenz abhängige imaginäre Impedanz eines derartigen Kondensators ist gegeben durch: Xc = (iωC)–1 (2)worin ω = 2πv die Kreisfrequenz darstellt und i = √–1 ist. Da das dielektrische Medium durch Glas gebildet wird, stellt der Ohmsche Verlust des Glases die Hauptquelle für den Verlust der gesamten Entladungslampe dar. Der Gesamtwiderstand des Kontaktbereichs beträgt: R = (ωε0ε''G)–1 (3)worin ε'' den – im Allgemeinen frequenzabhängigen – imaginären Teil der dielektrischen Funktion darstellt. Wenn eine Spannung im Kontaktbereich angelegt wird, ist der elektrische Widerstand, wie in 7 gezeigt, parallel zum Kondensator angeordnet, was zu der Impedanz Z führt: Z–1 = Xc –1 + R–1 (4) The contacts of the EEFL glass tubes are here formed by a cylinder having a radius r, typically 0.3 mm <r <10 mm, a thickness d of the glass tube of the order of 0.1 mm <d <0, 5 mm and a height l of the entire contact, which is in the order of 0.5 cm <l <5 cm. In this case, the total capacity can be approximated by a plate capacitor of thickness d and radius r together with a cylindrical capacitor of radius r and height I. The se geometry is in 7 shown. The total capacity of this geometry is:

where the last factor G only includes the effect of the geometry, ε ₀ = (μ ₀ c ² ) ^-1 = 8.855418710 ^-12 AsV ^-1 m ^-1 is the influential constant and ε 'is the real part of the dielectric constant. The frequency dependent imaginary impedance of such a capacitor is given by: X c = (iωC) -1 (2) where ω = 2πv represents the angular frequency and i = √-1. Since the dielectric medium is formed by glass, the ohmic loss of the glass is the main source of loss of the entire discharge lamp. The total resistance of the contact area is: R = (ωε 0 ε''G) -1 (3) where ε '' represents the - generally frequency-dependent - imaginary part of the dielectric function. When a voltage is applied in the contact area, the electrical resistance is as in 7 shown, arranged parallel to the capacitor, which leads to the impedance Z: Z -1 = X c -1 + R -1 (4)

The total electrical loss of such an RC element, wherein the ohmic resistance R at the frequencies used for use is much greater than the reactance of the capacitor R >> | X _c | results as follows:
The total current I _tot is mainly determined by the discharge lamp. The voltage dropping at the contact cap is determined by the capacitance: U cont = | X c | I dead (5)

The part of the current passing through the resistor is given by:

The total dielectric loss of such a contact is thus:

There an EEFL lamp has two such contacts multiplied you get the result with the factor 2 and set the geometry factor G on. For reasons the generally dynamic nature of the dielectric function one writes ε '(ω) and ε' '(ω).

Using the relationship for the dielectric loss tangent tan δ = ε '' / ε ', this leads to:

in this connection the important result is obtained that the dielectric loss, independently of the geometry of the cap, is proportional to the material dependent size tanδ (ω) / ε '(ω).

It should be noted that an exact calculation taking into account both the current through the resistor and the capacitor results in:

Since the tan δ is in the order of 10 ^-4 in most glasses, the tan ² δ (ω) in the denominator can be practically neglected in most glasses.

following the present invention will be explained by way of examples which the teaching of the invention illustrate, but not limit.

Examples

Glass compositions for glass bodies of bulbs with external electrodes are shown below and the quotient tan δ / DZ is given in each case. DZ is the dielectric constant. The quotients of all inventive glass compositions are well below 5, if tan δ is given in units of 10 ^-4 , and well below 5 × 10 ^-4 , if tan δ is given in absolute units, and therefore meet the specified requirements.

Table 1

Table 2

Further glass compositions and embodiments of the invention are given below:
In the following Tables 3 to 8 further glass compositions are given. Tables 3 to 7 show glasses according to the invention; Table 8 shows a comparative example. The glasses according to the present invention are preferably alkali-free.

In Tables 9.1 and 9.2 are for the glass compositions of Examples 15, 16 and 17 from the tables 3 and 4 and the Vergleichsbeipiel from Table 8, the dielectric Losses of the EEFL lamp indicated.

Specifically, the dielectric losses tan δ / ε 'for temperatures of 25 ° C, 150 ° C and 250 ° C and excitation frequencies of 10 kHz, 35 kHz and 70 kHz were listed in Tables 9.1 and 9.2. The power loss of the lamp is proportional to the quotient tan δ / ε '. The dielectric loss of an EEFL lamp was determined on the assumption that there is a cylindrical capacitor at both ends of the lamp, as previously described in connection with FIGS 6 and 7 was explained.

Further in Table 9 are the parameters used in the measurements detailed, such as radius of the tube of the lamp, thickness of the glass the lamp, length of the contact, the geometry factor and the prefactor etc.

The numerical values for the quotients of the glass compositions according to the invention are all below the upper limit of 5, when tan δ is given in units of 10 ^-4 , and below the upper limit of 5 × 10 ⁴ , if tan δ is given in absolute units, and show Thus, a significantly lower dielectric loss than in the comparative example, after which the quotient exceeds the critical upper limit.

The measurements thus confirm that it is not decisive to set the individual values of loss angle tan δ and the dielectric constant ε 'independently of one another as low as possible, but the two values must be related to one another. Surprisingly, based on the be voted values prove that the quotient of both parameters represents the critical size with which the adjustment of the glass material properties succeeds, and not tan δ alone or ε 'alone. Accordingly, with the present invention, the total power dissipation of the luminous means with external electrodes can be minimized specifically via the glass properties.

Table 3

Table 4

Table 5

Table 6

Table 7

Table 8

Table 9.1 below shows the calculated quotient tanδ / ε '(calculated from the measured values tanδ and ε'): Table 9.1

Numerical example that applies to all values in Table 9.1: tanδ / ε 'with tanδ in [10 ^-4 ] = 6.9 (at 25 ° C) or with tanδ as absolute value tanδ / ε' = 0.00069

Out Table 9.1 above it is immediately apparent that the glasses according to the invention in 250 ° C one to about 20 times lower quotients than the comparative example.

wobei gilt:

Based on these quotients, the respective power losses (P _loss ) for a lamp were calculated with the following parameters:

where:

mit
π = 3,141592654
ε₀ = 8.8542 10^–12 As/(Vm)The exact calculation is done with the previously derived formula (11), where G can replace the above formula (12) and then:

With
π = 3.141592654
ε ₀ = 8.8542 10 ^-12 As / (Vm)

With The parameters given above then result in the following Table 9.2 combined power losses for the different Frequencies 10 Hz, 35 Hz and 70 Hz.

Table 9.2

The used frequencies of 10 kHz, 35 kHz and 70 kHz were selected because the lamps of interest, in particular EEFLs with external ones Electrodes, usually be operated at frequencies around 70 kHz. This also goes from the previously cited references (Cho G. et al., J. Phys. D: Appl. Phys. Vol. 37, (2004), pp. 2863-2867 and Cho T.S. et al., Jpn. J. Appl. Phys. Vol. 41, (2002), pp. 7518-7521). That the lamps with the glasses according to the invention were under operating conditions tested.

at The measurements were made in a voltage ranging from 500V to 6 kV, in particular 2 kV, preferably 1 kV, applied and between the Basic values, i. for example, between + 2kV and - 2kV, down and hergeschaltet. This alternating voltage can, for example, sinusoidal, sawtooth, triangular or rectangular be. Other shapes are also possible.

Exemplary are in 8th a sinusoidal and a rectangular voltage with the parameters + 2kV and - 2 kV shown. To generate high voltage from the existing mains voltage, an inverter was used in the present case, which represents an electronic component that provides voltages in the range of 500 V to 6 kV with a periodic timing. This inverter is switched electrically in front of the lamp.

It can now be seen from Table 9.1 that glasses used in the displays according to the invention show a power loss which is up to 36 times lower than the glass of the comparative example. It is thus proved that these glass compositions actually show extremely low dielectric losses, and thus much less heat development is present in the glass than in a comparative glass, resulting in a better efficiency a lighting device and thus longer durability results.

One Another problem of EEFLs is the so-called "pinhole burning", which is a breakdown designated at high voltages. If such a breakdown occurs, this causes leaks in the glass. This will be in the above References by Cho et al. described in detail. Surprisingly has now been shown that the glass compositions used, prefers the glass compositions listed in the tables, in particular those of the embodiments 15, 16 and 17, which are alkali-free glasses, no pinhole burning show. An undesirable Throbbing even kicked in the raw glasses not up to 6 kV. This confirms the suitability of the glasses for one Use in the field of lamps, especially EEFL lamps.

The present invention thus describes a backlit display, wherein the glass hollow body of the luminous means has a glass composition in which the glass properties can be influenced in a targeted manner by adjusting the quotient of the loss angle tan δ and the dielectric constant ε '. By observing the upper limit of the invention of 5 × 10 ^-4 for the quotient, it becomes possible for the first time with the teaching of the invention to minimize the total power loss of glass compositions and thus to obtain optimum efficiency in lamps with external electrodes.

Claims (48)

Display, in particular flat display, with backlight for mobile phone, motor vehicle, television, computer, household and cameras, comprising at least one light source with external electrodes, which has a glass hollow body, characterized in that the glass composition for the glass hollow body of the light source is selected such that the quotient of the loss angle (tan δ) and the dielectric constant (ε ') applies:

Display according to claim 1, characterized in that the quotient

is, in particular

is. Display according to claim 1 or 2, characterized in that the quotient

especially

is. Display according to at least one of the preceding claims 1 to 3, characterized in that by setting the quotient tanδ / ε '<5 × 10 ^-4 a high efficiency of the luminous means by a low power loss P _loss results from:

where: ω: angular frequency tan δ: loss angle ε ': dielectric constant d: thickness of the capacitor (here: thickness of the glass) A: electrode area and I: current ε ₀ : Influence constant = 8.8542 10 ^-12 As / (Vm). Display according to at least one of the preceding claims 1 to 4, characterized in that the size of the display in the area from 50 × 50 mm to 4 × 5 m is located. Display according to at least one of the preceding claims 1 to 5, characterized in that the display comprises: a glass pane, in particular a structured glass pane, a liquid crystal layer, Polarization units and another glass panel for the display. Display according to at least one of the preceding claims 1 to 6, characterized in that the display is a light distribution unit includes a polymer with scattering centers, glass, phase-separated glass or glass ceramic. Display according to claim 7, characterized that the light distribution unit inhomogeneously distributed scattering centers for optimal homogeneous light distribution. Display according to at least one of the preceding claims 7 or 8, characterized in that the light distribution unit a structured surface or defined surface roughness with rms values in the order of magnitude the wavelength of light has, preferably with 20nm <rms <100,000 nm, especially preferably 10 nm <rms <10000 nm. Display according to at least one of the preceding claims 7 to 9, characterized in that the light distribution unit as a hollow body is formed, whose walls by reflecting the light, and by the surface roughness the light is disconnected. Display according to at least one of the preceding claims 1 to 10, characterized in that the luminous means a discharge lamp, in particular a fluorescent lamp, more preferably an EEFL lamp. Display according to claim 11, characterized that the bulbs have a round, oval, rectangular and / or having flat, rectangular cross-section. Display according to at least one of the preceding claims 11 or 12, characterized in that the following applies to the glass of the glass hollow body of the luminous means with external electrodes:

at the application frequencies in the range of 5-200 kHz, preferably 10-150 kHz, more preferably 20-100 kHz. Display according to at least one of the preceding claims 1 to 13, characterized in that the glasses used are selected for the glass hollow body from glasses with high polarizability (dielectric constant ε '> 5). Display according to at least one of the preceding claims 1 to 14, characterized in that the glasses used for the glass hollow body are selected from glasses with low conductivity, in particular with tan δ <20 × 10 ^-4 , more preferably tan δ <1 × 10 ^-4 , Display according to at least one of the preceding claims 1 to 15, characterized in that the glasses are selected for the glass hollow body from glasses with UV blocking. Display according to Claim 16, characterized that the UV blocking in the glasses adjusted by incorporation of rare earth or transition metal ions, especially selected of Ti, Ce, W, Nb, Bi, Yb, Fe, Ni, in the glass matrix. Display according to Claim 16, characterized that the UV blocking by providing an inner or outer coating of the glass hollow body of the bulb is set. Display according to at least one of the preceding claims 1 to 18, characterized in that the hollow glass body a filling of a gas selected from Hg gas, noble gas, in particular Xe gas, or mixtures thereof having. Display according to at least one of the preceding claims 1 to 19, characterized in that an inner coating of the Glass hollow body for converting light from UV or blue light to white light in total with a fluorescent layer of a solid powder containing rare earth ions is doped, is provided. Display according to at least one of the preceding claims 1 to 20, characterized in that a doping of the glass of the glass hollow body for converting light from UV or blue light to white light in total provided by fluorescent rare earth ions and / or transition metal ions is. Display according to at least one of the preceding claims 20 or 21, characterized in that the rare earth ions are selected from Ce, Eu, Tm, Tb, Dy and / or Gd. Display according to at least one of the preceding claims 1 to 22, characterized in that the contacts on the glass hollow body of the Illuminant selected are made a) metal or sheet metal; b) dip coatings of metal or metal-containing conductive substances; c) conductive ink or d) conductive adhesive tape. Display according to at least one of the preceding claims 1 to 23, characterized in that for heat management at the light source for passive cooling cooling plates or for active cooling (on) Fan (s) and / or liquid cooling provided are. Display according to at least one of the preceding claims 1 to 24, characterized in that means for controlling the Illuminant with external Electrodes with alternating voltages of 0.5-10 kV, particularly preferred 0.8-6 kV in the frequency range of 5-200 kHz, preferably 10-150 kHz, particularly preferably 20-100 kHz are provided. Display according to Claim 25, characterized that the means for controlling the bulbs with external Electrodes sinusoidal Signals, preferably rectangular Signals, use. Display according to at least one of the preceding claims 25 or 26, characterized in that the means an electronic Actuator representing the voltages and waveforms generated. Display according to Claim 27, characterized that the electronic drive unit with a current limit is provided. Display according to at least one of the preceding claims 1 to 28, characterized in that the lighting means is a high-pressure lamp in which the or the pressurized filling gases on so high temperatures come, that creates a continuous spectrum or, if Hg and / or Xe gas is included as the filling gas, an additional one there is strong impact broadening of the Hg and / or Xe line spectrum, the above external electrodes can be controlled. Display according to at least one of the preceding claims 1 to 29, characterized in that the hollow glass body a Glass composition comprising at least one highly polarizable Contains element in oxidic form in the glass matrix, the from the group consisting of the oxides of Ba, Cs, Hf, Ta, W, Re, Os, Ir, Pt, Pb, Bi, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and / or Lu selected is. Display according to claim 30, characterized that or the hochpolarisierbaren elements in oxidic form in an amount of at least 8, preferably 12, more preferably 15, in particular of 20 wt .-% or more. Display according to claim 30, characterized that or the hochpolarisierbaren elements in oxidic form in an amount of at least 20, preferably 25, more preferably 35, in particular 40 wt .-% or more. Display according to at least one of claims 1 to 32, characterized in that the glass hollow body comprises one of the following glass compositions:

which is ΣAl ₂ O ₃ + B ₂ O ₃ + BaO + PbO + Bi ₂ O ₃ 10-80% by weight, wherein Hf, Ta, W, Re, Os, Ir, Pt, La, Pr, Nd, Sm , Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and / or Lu in oxidic form in contents of 0 - 80 wt.%, As well as refining agents in usual concentrations. Display according to at least one of the preceding claims 1 to 32, characterized in that the glass hollow body comprises one of the following glass compositions:

which is ΣAl ₂ O ₃ + B ₂ O ₃ + BaO + PbO + Bi ₂ O ₃ 10-80% by weight, and refining agent in conventional concentrations. Display according to at least one of claims 1 to 32, characterized in that the glass hollow body comprises one of the following glass compositions:

which is ΣAl ₂ O ₃ + B ₂ O ₃ + BaO + PbO + Bi ₂ O ₃ 8-65% by weight, wherein Hf, Ta, W, Re, Os, Ir, Pt, La, Pr, Nd, Sm , Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and / or Lu in oxidic form in contents of 0-80 wt.% Are present, and refining agent in conventional concentrations. Display according to at least one of claims 1 to 32, characterized in that the glass hollow body comprises one of the following glass compositions:

which is ΣAl ₂ O ₃ + B ₂ O ₃ + BaO + PbO + Bi ₂ O ₃ 10-80% by weight, wherein Hf, Ta, W, Re, Os, Ir, Pt, La, Pr, Nd, Sm , Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and / or Lu in oxidic form in contents of 0-80 wt.% Are present, and refining agent in conventional concentrations. Display according to at least one of the preceding claims 1 to 36, characterized in that the content of alkali in the Glass composition of the glass hollow body <1.0 wt .-% is. Display according to at least one of the preceding claims 1 to 37, characterized in that the glass of the glass hollow body free of alkali. Display according to at least one of the preceding claims 1 to 38, characterized in that the content of BaO in the Glass composition of the glass hollow body greater than 15 wt .-%, preferably greater than 18 wt .-% is. Display according to at least one of the preceding claims 1 to 38, characterized in that the content of BaO in the Glass composition of the glass hollow body is greater than 20 wt .-% is. Display according to at least one of the preceding claims 1 to 38, characterized in that the content of BaO in the glass composition of the glass hollow body between 20 wt .-% and 80 Wt .-%, preferably between 20 and 60 wt .-% is. Display according to at least one of the preceding claims 1 to 41, characterized in that when the content of PbO in the glass composition of the glass hollow body greater than 50 wt .-%, in particular greater than 60 wt .-%, the alkali content is greater than 3 wt .-%, preferably greater than 4% by weight, most preferably greater than 5% by weight is. Display according to at least one of the preceding claims 1 to 41, characterized in that when the glass composition of the glass hollow body contains no PbO, the content of alkali <1.0% by weight is, preferably no alkali is included. Display according to at least one of the preceding claims 1 to 42, characterized in that when the glass composition of the glass hollow body Contains PbO, the content of BaO <10 Wt .-%, preferably <5 Wt .-%, particularly preferably no BaO is contained. Display according to at least one of the preceding claims 1 to 32, characterized in that the glass of the glass hollow body contains SiO ₂ with or without doping oxides or consists thereof. Display according to claim 45, characterized in that the glass of the glass hollow body comprises one of the following compositions:

where the upper limits of the SiO ₂ content is given by: 100 wt .-% - (minus) all lower limits of the oxides present, except SiO ₂ . Display according to claim 45 or 46, characterized in that the glass of the glass hollow body consists of SiO ₂ . Using the display after at least one of preceding claims 1 to 47 in electronic devices, in particular for display and display applications, such as LCD displays, in computer monitors, like TFT devices, Telephone displays, such as mobile phones, scanners, advertising signs, medical Instruments and devices aerospace, as well as navigation technology and in PDAs (Personal Digital Assistant).