EP2215895A2

EP2215895A2 - High-frequency lamp and method for the operation thereof

Info

Publication number: EP2215895A2
Application number: EP08855170A
Authority: EP
Inventors: Holger Heuermann
Original assignee: Dritte Patentportfolio Beteiligungs GmbH and Co KG
Current assignee: Dritte Patentportfolio Beteiligungs GmbH and Co KG
Priority date: 2007-11-28
Filing date: 2008-11-27
Publication date: 2010-08-11
Also published as: JP5591117B2; US8450945B2; US20100253238A1; CN101884250A; MX2010005521A; BRPI0817216A2; TW200939883A; WO2009068618A2; CA2706389A1; DE102007057581A1; KR101441608B1; KR20100105579A; JP2011505060A; WO2009068618A3; RU2502236C2; CN104602424A; TWI454183B; CN104602424B; RU2010126150A

Abstract

The invention relates to a novel design for constructing a high-frequency lamp (10) for low and high-pressure applications and a method for the operation thereof, particularly suitable for improving the characteristics with regard to efficiency, emission spectrum, cost, and long life, in that the use of an exciter unit is no longer necessary, even at very low high-frequency power, due to an impedance transformer (26) connected downstream from a power amplifier (20), because the application of as high a voltage as possible to an ionization chamber (16) is possible using the impedance transformation.

Description

description

High frequency lamp and method of operation

The invention relates to a high-frequency lamp, hereinafter sometimes referred to briefly as an RF lamp, according to the preamble of claim 1. It further relates to a method for operating such a high-frequency lamp according to the preamble of claim. 9

Such high frequency lamps are well known.

The task of every lamp, including a high-frequency lamp, is to emit light as efficiently as possible. Each lamp converts energy into light with more or less good efficiency. Often, a lot of heat is lost during conversion.

Further tasks of lamps are manifold. Often, the emitted light spectrum is very crucial to the purpose. Similarly, some applications, such as vehicle headlights and projectors, need lamps with point sources as possible.

The description of the prior art will be further limited to electric lamps. These can be roughly differentiated into light-emitting diodes and lamps with glass bodies. Here, the last group will be discussed below. This is divided into light bulbs and gas discharge lamps.

Incandescent lamps have inside the glass body a filament (eg tungsten) and a protective gas. The filament with a melting point of about 3000 ⁰ C is heated to typically 2500 ⁰ C. According to the Planck's radiation law does not result in a light spectrum corresponding to daylight for the incandescent lamp, but it shines distinctly yellowish-reddish. Incandescent lamps are operated with a DC or an AC voltage with frequencies up to the kHz range. You do not need ballast electronics.

Gas discharge lamps related to the invention are light sources which use a gas discharge utilizing spontaneous emission by atomic or molecular electronic transitions and the recombination radiation of an electrical discharge generated plasma. The gas contained in the quartz glass bulb (ionization chamber) is often a mixture of metal vapors (eg mercury) and noble gases (eg argon) and possibly other gases as well as halogens. Gas discharge lamps are divided into the two classes of low and high pressure discharge lamps. The former uses a glow discharge and the latter uses an arc discharge. These lamps all require a ballast. This contains a starter, which ionizes the gas by means of a voltage pulse in the kV range. Furthermore, if necessary, the frequency is converted into the kHz range for continuous operation. Consequently, these lamps are not lamps which are operated by means of a high-frequency signal in the MHz or GHz range.

A special form of the gas discharge lamp is the sulfur lamp. It consists of a quartz glass ball filled with sulfur and argon as the ionization chamber. In the glass ball, a plasma is generated by high-frequency radiation. In contrast to conventional gas discharge lamps, the sulfur lamp requires no electrodes because of the use of waveguides. Because of the extremely high temperatures that arise on the quartz glass of the sphere, it is kept in rotation and thereby cooled. This causes a lower stem having turbine blade-like fan-out. It turns in the air flow, which is generated by a fan inside the magnetron (HF power source with approximately 1500W). If this cooling fails, the glass ball would melt after 20 seconds.

Sulfur lamps have a similar luminous efficacy as energy-saving lamps (fluorescent lamps). They have a balanced luminous spectrum with about 5700 K to 6000 K color temperature and are thus very effective white light sources. By regulating the performance of the

Magnetrons are well dimmable to sulfur lamps, their color spectrum remains stable. Due to the high luminous flux, the lamps are usually not installed directly at the place of use. Instead, the light is guided into the room with the help of light guides. This makes this lamp type easy to maintain.

Due to the relatively high expenditure on equipment (power supply for magnetron, shielding of the microwaves, temperatures), this lamp was not commercially available for a long time. Since 2006, LG Electronics has been producing sulfur lamps under the name "Power Lighting System" (PLS lamps, also available as Sulfur Plasma lamps). They are often used as lighting in television studios or as artificial lighting for plants.

From "Emission Properties of Compact Antenna Excited Super-High Pressure Mercury Microwave Discharge Lamps", T. Mizojiri, Y. Morimoto, and M. Kando in Japanese Journal of Applied Physics, Vol. 6A, 2007, and "Numerical analysis of antenna-excited microwave discharge lamp by finite element method", M. Kando, T. Fukaya and T. Mizojiri; 28th IC-PIG, Juicy 15-20, 2007, Prague, Czech Republic are high-frequency lamps known that work with small high-frequency power (30-100W) and instead of the waveguide coupling have a coupling via a TEM line (coaxial line) with inner conductor electrode. Since these lamps use the long wires of a glass discharge lamp as an antenna, these lamps will be more appropriately referred to as RF antenna lamps hereinafter.

However, these lamps, as well as the sulfur lamps, have no impedance transformers. Thus, the requirements for frequency stability of the high-frequency generator are low in these lamps.

A disadvantage of these known gas discharge lamps, however, is that the technology for these lamps is very expensive and therefore expensive. In addition, they are only available as a power lamp with about 1500 W. In addition, all previously known gas discharge lamps require a separate circuit for igniting the plasma. Voltages in the kV range are needed here. The hitherto known high-frequency lamps, which manage without ignition circuit, has the disadvantage that they require a great deal of power (over 30 W microwave power). Furthermore, gas discharge lamps act as antennas. This has the serious disadvantage in practice that high-frequency radiation is emitted to a greater extent. Such lamps are not allowed due to this radiation.

The gas discharge lamps used as energy-saving lamps are not dimmable, which represents a very great disadvantage in practical use.

Because the previous high-frequency lamps have no impedance transformation in the high-impedance range, very large currents flow through the Electrodes. Since these are made of materials such as tungsten with a poor surface finish, the ohmic losses are very large.

Accordingly, it is an object of the invention to provide a high-frequency lamp which satisfies the above-mentioned requirements. Disadvantages avoids or at least reduces their effects, in particular to provide a structure of a high-frequency lamp, which can be used both as high-pressure and low-pressure gas discharge lamp and is particularly suitable to improve properties such as efficiency, emission spectrum, costs and longevity. Another object of the invention is to provide a method of operating such a high frequency lamp.

This object is achieved on the one hand with a high-frequency lamp with the features of claim 1. This is at one

High-frequency lamp having a signal generating area for generating a high-frequency signal and that, ie the signal generating area, downstream ionization chamber, wherein the signal generating portion includes a switchable high frequency oscillator and at its output a power amplifier for increasing a power of the high frequency signal and wherein the ionization chamber, the at least one Gas-filled glass bulb comprises, at least one electrode is assigned, provided that the power amplifier, an impedance transformer is connected downstream, which is connected at its output to the or each electrode.

With regard to the method, this object is achieved according to the invention by the features of claim 9. It is provided that for the operation of a high-frequency lamp of the type outlined and subsequently described, the high-frequency signal from the radio frequency quenzoszillator is generated, wherein the power of the high-frequency signal is increased by the downstream power amplifier, that the high-frequency signal is transformed by the power amplifier downstream impedance transformer in the high voltage region and that the transformed high-frequency signal is supplied to the electrode.

The advantage of the invention consists firstly in the fact that a high-frequency oscillator can be used in the signal generation region of the high-frequency lamp, which can be changed via a voltage and is available as a low-cost module. In addition, the output of the high-frequency oscillator, which is typically in the mW range, can be increased in the one to two-digit watt range by a power amplifier, which has both a high efficiency, as well as inexpensive. Finally, the use of an impedance transformer, which is used to apply the highest possible voltage to the ionization chamber, saves the use of an ignition unit even at very low RF power. Furthermore, a significantly higher ionization rate and thus greater efficiency is achieved by the large permanently applied electric field strength. Since the high-frequency power is permanently coupled with a high voltage by the impedance transformer, the ohmic losses at the electrode tips, which are made of poorly conductive materials, are lower, thereby increasing the efficiency. In addition, due to the operation in the high frequency range, a large number of circuit options are available as an impedance transformer so that it can also be achieved with low-cost components such as capacitors and coils.

The construction of a high-frequency lamp with such a signal generating area is also advantageous in that no high frequency quenzabstrahlung outside the high frequency lamp takes place and it is therefore eligible.

For the electrode associated with the ionization chamber, different materials can be used and molds can be used, which can improve both efficiency and field of application.

Advantageous embodiments of the invention are the subject of the subclaims. The relations used point to the others

Education of the subject of the main claim by the features of the respective dependent claim; they should not be construed as a waiver of obtaining independent, objective protection for the feature combinations of the dependent claims. Furthermore, with a view to an interpretation of the claims in a closer specification of a feature in a subordinate claim, it is to be assumed that such a restriction does not exist in the respective preceding claims.

According to a preferred refinement of the high-frequency lamp, it is provided that the signal generating area additionally comprises a coupler connected downstream of the power amplifier, in particular between power amplifier and impedance transformer, a high-frequency detector and a processing unit, wherein a high-frequency signal reflected at the electrode during operation of the high-frequency lamp can be fed to the high-frequency detector via the coupler and wherein a control or actuating signal which can be generated by the processing unit on the basis of an output signal of the high-frequency detector can be fed to the high-frequency oscillator for optimizing the high-frequency signal on the basis of the reflected signal. By detecting the reflection optimized high-frequency signal whose optimization is possible, for example after ignition of the high-frequency lamp to then possible reduction in the frequency of the high-frequency signal. Additionally or alternatively, a control of the high-frequency oscillator is possible based on the reflected high-frequency signal.

If the high-frequency lamp is configured such that the high-frequency oscillator is followed by a signal divider with a first and second signal divider output and the power amplifier is connected to the first signal divider output, wherein the second signal divider output means for phase shifting - hereinafter also referred to as "phase shifter" and z. B. realized in the form of a 180 ° long line -, a second power amplifier, a second impedance transformer and a second electrode are connected in series, can be applied with a high-frequency oscillator, the ionization chamber with an opposite phase signal. This embodiment will be referred to below to distinguish from the embodiment described above with only one power amplifier, an impedance transformer and an electrode as a symmetrical structure.

It is further preferred that the impedance transformer or, in the case of a high-frequency lamp with a symmetrical construction, the impedance transformer and / or the second impedance transformer, comprises a single-stage or multi-stage transformer-effective section, the advantage of the single-stage transformation being above all its compactness and robustness, while with a multi-stage transformation, an improvement in the efficiency of the impedance transformer can be achieved. If the or each electrode is dielectric, ie made of a dielectric material, in particular formed by a metal core surrounded by a dielectric sheath, excellent efficiencies and highest color temperatures can be achieved.

If the or each electrode is loop-shaped, the occurrence of unwanted cavity modes can be avoided, which again applies to the high-frequency lamp with a symmetrical structure.

If the glass bulb is filled with a mixture of at least two gases, in particular exactly three gases, with different emission spectra, different colors can be ionized by suitably changing the frequency of the high-frequency signal. If the high-frequency signal comprises a frequency spectrum which is suitable for ionizing more than one gas, a color mixture results correspondingly for the perceived, emitted light. In this way, two, three or more colors can be directly ionized by a narrow-band high-frequency signal, while with appropriately selected wide-band high-frequency signals, an ionization of several colors and their superimposition, a generation of mixed colors is possible. This embodiment of the high frequency lamp is suitable for lighting effects, such as self-luminous advertising materials, or for display instruments.

According to an embodiment which is alternative to the previously described embodiment, however, it is provided that the ionization chamber comprises at least two glass flasks, in particular three glass flasks, which are each filled individually with a gas having different emission spectra and wherein each glass flask has an electrode for supplying a high-frequency signal assigned. In this version tion form gives each glass bulb in ionization of the gas contained therein each characteristic emission spectrum. Put simply, each glass bulb radiates exactly one color. By controlling the electrode assigned to the respective glass bulb, it is thus possible for the high-frequency lamp as a whole to emit a first or second (or third and possibly further) color (s) or the color mixture possible when simultaneously emitting a plurality of colors. This embodiment of the high-frequency lamp is also considered for the generation of light effects. However, there is also the at least fundamental suitability as an imaging element in display devices in the manner of a monitor. For the latter case, one will usually provide three glass flasks, which - in accordance with the known RGB model - are intended for the emission of red, green and blue light. In connection with this aspect of the invention, a plurality of such high-frequency lamps arranged in rows and columns can be combined to form a display device, that is to say a monitor, a television and the like. In that regard, the invention also relates to a method suitable for operating such a display device, in which each high-frequency lamp included is operated such that either at least two high frequency signals are generated by the high frequency oscillator and the at least one electrode supplied or generated by the high frequency oscillator at least two high frequency signals and each high frequency signal accurately one of the at least two electrodes is supplied. In this way, any visible image which can be generated by the display device can be individually controlled by exactly one pixel, a "pixel", corresponding high-frequency lamp and achieve a desired color emission, a desired color value, for the respective pixel / pixel. With regard to the method according to the invention, as described above, according to the invention, embodiments of the method for operating the respective representational developments of the high-frequency lamp are also provided.

In order to operate one of the preferred embodiments of the high-frequency lamp, it is correspondingly provided that the high-frequency detector detects the high-frequency signal reflected at the electrode when the high-frequency lamp is ignited and relayed via the coupler, and in that the processing unit optimizes the control signal for optimizing the high-frequency signal on the basis of the output signal of the high-frequency detector, in particular varies by a given positive or negative value. With regard to the aspect of the adaptation of the high-frequency signal, the advantage lies in the fact that before or during the ignition of the high-frequency lamp, the ionization chamber acts as a small capacitor with high-impedance parallel resistance, while immediately after the ionization (lighting operation) increases the capacity and reduces the parallel resistance Thus, therefore, after ignition, the resonance frequency, the frequency to be used for the high-frequency signal, changes. For this reason, the signal generation after ignition of the lamp must be able to perform a quick one-time frequency hopping, the high-frequency signal is thus "adapted" to the situation of lighting operation. For the components coupler and high-frequency detector, this means that, if the high-frequency lamp ignites, a significantly greater RF power is reflected at the electrode. This passes to the coupler and is fed via this attenuated the high-frequency detector. The changed output signal of the high frequency detector is received by the processing unit and this performs the frequency hopping for the lighting operation. With regard to the aspect of the variation of the high-frequency signal, the advantage lies in the fact that with a variation of the high-frequency signal by a small positive and a small negative value, the reflected powers for a plurality of frequency points, eg for an average frequency, a reduced frequency and increased Frequency, measured and the value with the lowest reflected power is used as a new output value for the high-frequency signal. This regulation is repeated continuously or at predefined or predefinable times. This ensures that as much HF power as possible is always fed into the ionization chamber and converted as little as possible into heat losses.

To operate the high-frequency lamp with a symmetrical structure, it is correspondingly provided that the signal divider separates a second high-frequency signal from the high-frequency signal, in particular such that a high-frequency signal remaining as a high-frequency signal and the second high-frequency signal are at least substantially identical, that the means for phase shifting is the second In phase shifts high frequency signal, the downstream second power amplifier increases the power of the phase-shifted second high-frequency signal and the downstream second impedance transformer transforms the resulting second high-frequency signal in one or more stages and forwards to the second electrode.

For other embodiments of the high-frequency lamp, it is provided that at least two high-frequency signals are generated by the high-frequency oscillator and supplied to the at least one electrode or that at least two high-frequency signals are generated by the high-frequency oscillator and each high frequency signal is fed to precisely one of the at least two electrodes.

An embodiment of the invention will be explained in more detail with reference to the drawing. Corresponding objects or elements are provided in all figures with the same reference numerals.

The or each embodiment is not to be understood as limiting the invention. Rather, numerous modifications and modifications are possible within the scope of the present disclosure, in particular those variants, elements and combinations and / or materials, which are described, for example, by combination or modification of individual in conjunction with the general or specific description part as well as in the claims and / or features contained in the drawing or elements or method steps for the skilled worker with regard to the solution of the task can be removed and lead by combinable features to a new subject or to new process steps or process steps, even if they manufacturing or working procedures affect.

In the drawing show

1 shows a schematically simplified block diagram of a high-frequency lamp for a so-called control operation, FIG 2 is a schematically simplified block diagram of the high-frequency lamp for a control operation,

3 shows a schematically simplified block diagram for a high-frequency lamp with differential control ("symmetrical structure"), 4 shows a lamp head with single-stage impedance transformation, that is to say with a single-stage transformatively effective section,

FIG. 5 shows a lamp head with a three-stage impedance transformation, that is to say with a multistage transformer-effective section, FIG.

6 shows an EorMode in a circular waveguide (dashed E-field, H-solid drawn through),

7 shows a cavity resonator lamp with single-stage impedance transformation for the excitation of the Eoi mode with asymmetrical excitation,

8 shows a coupling of a dielectric electrode for the excitation of a HE-n fundamental mode,

9 shows a coupling of a dielectric electrode for the excitation of the EorModes, and FIG. 10 shows a schematically simplified illustration of a high-frequency lamp over a mass plate for a point light generation with symmetrical activation from one side.

1 shows schematically simplified the structure of an embodiment of a generally designated 10 high-frequency lamp according to the

Invention. This comprises a signal generating section 12 for generating a high-frequency signal 14 and an ionization chamber 16 connected downstream of the signal generating section. The signal generating section 12 in turn comprises a high-frequency oscillator 18 and at its output a power amplifier 20 for boosting a power of the high-frequency signal 14. The ionization chamber 16 in turn comprises at least one gas-filled glass bulb 22 (gas 24, possibly supplemented by metal vapors and / or halogens), which is associated with at least one almost arbitrarily configurable electrode 28. For the signal generating region 12, it is provided that the power amplifier 20 has a Impedance transformer 26 is connected at its output to the or each electrode 28 is connected. An outer shield of the signal generating circuit forms a mass 30, with which the electrode 28, which leads the RF signal 14 as the feedthrough electrode into the interior of the ionization chamber 16, capacitively coupled.

In this way, the structure of a high-frequency lamp 10 (RF lamp) based on a relatively narrow-band high-frequency signal 14 (in the three-digit MHz and total GHz range), which is converted by means of the impedance transformer 26 in a high voltage range, and a wide almost arbitrarily configurable Arc region that does not reach 30 to the mass, as it is on an inner surface of the glass bulb 22, eg a quartz glass used for its production ends, possible.

The intended impedance transformer 26 also saves the use of a previously required for high-frequency lamp 10 ignition unit even with very small RF power. Furthermore, a significantly higher ionization rate and thus greater efficiency is achieved by the large permanently applied electric field strength. Because high frequency power is permanently coupled in with a high voltage, the ohmic losses at the tips of the or each electrode 28, which have poorly conductive materials, are lower, which in turn increases efficiency. A simple embodiment of an impedance transformer 26 includes a coil and a capacitor. When using 0402 SMD components, space is less than 2mm ² and costs less than 4 cents.

The higher the frequency of the high-frequency signal 14 is selected, the smaller the voltage applied to the electrode 28 can be. Already In the lower GHz range, for which there are many low-cost electronic components, the voltage can be reduced to single-digit kV values in the lower range, depending on the desired arc length. This reduction of the maximum stress allows implementation with significantly less expensive materials and components.

Because working with narrow-band high-frequency signals 14, an HF-compatible structure is very easy. For example, it is now possible to use lambda / 2 lines with all their advantages. That Lines do not have to have the desired characteristic impedance.

This simplifies e.g. a high-frequency design of the high-frequency lamp 10.

The electrode 28 now radiates the energy over several paths or a large area. The electromagnetic energy generated in the ionized region around the electrode 28, an RF current that emits radiant energy due to the heating radiant energy in the optical range. Thus, the energy output from the electrode 28 is no longer as a stream, but as an electromagnetic field. The electrode 28 is no longer loaded by the current flow. Initial measurements have shown that no

Material exits. The high frequency lamp 10 can thus be used over a longer life.

As a power amplifier 20 are highly integrated and cheapest high-frequency power amplifier for GSM mobile applications and handsets into consideration, have the efficiencies of over 60%. Efficiencies of 80% are achievable in the so-called class E-Betheb.

Short lines can be realized almost lossless in the lower GHz range. Thus, for the signal acting as HF-Vorschalteinheit signal Generation range 12, which is preferably integrated in one foot of the high-frequency lamp (lamp base), also given the potential for a very good efficiency and thus a highly integrated feasibility.

The choice of material for the electrode structure allows not only metal but also the use of a dielectric material. For example, the electrode 28 may be made of a ceramic material having a high dielectric constant and a very high melting point. This design is a very decisive point with regard to the color temperature and the often desired spectrum, which corresponds to daylight. As a result, a significantly improved efficiency can be achieved.

An additional advantage of this lamp over all energy-saving lamps is that the high-frequency lamp proposed here is dimmable.

Teach fundamental physics books that the ionization of a gas nenstrahleinschuss only by the electron impact, excited by an electrical, thermal ionization at extremely high temperatures (10 K ⁶⁾ or photoionization by means of ultraviolet light. Moreover, in the GHz range, the inventor has realized experimental physics constructions by means of which ionized regions have arisen via the introduction of relatively little high-frequency energy. These results coincide with other published results, eg. B. "experiments with high frequency" by H. Chmela, Franzis-Verlag, which were carried out in the MHz range. This will be referred to hereinafter as high-frequency ionization. Also in "A Novel Spark Plug for Improved Ignition in Engines with Gasoline Direct Injection (GDI)" by K. Linkenheil and others, IEEE Transactions on Plasma Science, VoI 33, No. 5, Oct. In 2005, this high frequency ionization is detected and highlighted that additional UV radiation allows this ionization at lower electric field strengths.

If an ionized gas has the same number of electrons and ions, then it is a gas that is space-charge-free and called plasma.

It can be shown from Maxwell's equations that the following mathematical relationships apply to an ionized gas:

Relative Dielectric constant: e _r = 1 - (N e ² ) / e ₀ / m / (u ² + w ² ) (1)

Relative conductivity: k = (N e ² u) / m / (u ² + w ² ) (2)

Plasma frequency: wp = e (N e ² / m / e ₀ ) (3) with the quantities:

N: number of electrons per volume, e: charge of an electron, m: mass of an electron, eo: electric field constant, u: frequency of the collisions of the electrons with the gas molecules, w: frequency of the high frequency signal.

Detailed investigations show that below the plasma frequency no electromagnetic energy is capable of propagation and no losses te be held in the plasma. By contrast, the space has a real field impedance Zf above the plasma frequency. Zf drops to higher frequencies and exponentially approaches the free space resistance Z ₀ of around 377W. This means that at higher frequencies, lower voltages are required to achieve the same power levels than at lower frequencies

Frequencies. Equation (2) shows that the (small) resistance and thus the losses increase with increasing frequency. Consequently, at higher frequencies, the gases can be heated better.

An analysis of the atmosphere for the transmission properties of the RF signals shows that in the two- to three-digit MHz range, the radiation is almost not absorbed, while at 50 GHz, the entire radiation is absorbed as molecular absorption in hydrogen or oxygen. In the lower MHz range, so-called Tesla transformers can be used to manufacture 10OW generators with a 5kV output voltage and thus produce 10cm spark gaps in air, cf. also the already mentioned reference "Experiments with high frequency", a.a.O. The inventor has already generated a 1 cm long spark gap at 2.5 GHz using a 10 W transmitter and a voltage of 2 kV.

In the following, the signal generation in the high frequency lamp 10 will be described. In the initial state (ignition operation), the ionization chamber 16 acts as a small capacity with high resistance parallel resistor. Immediately after the ionization (lighting operation), the capacity increases and the parallel resistance decreases. Consequently, after ignition, the resonance frequency f _{r changes} . For this reason, it is advantageous if the signal generation, that is to say the functionality of the signal generation region 12, after ignition of the high-frequency lamp 10 is capable of producing a fast one-time frequency jump of f _M to perform after f _r2 . It is important that the output resistance Z _from the signal generation 12 corresponds to the input resistance Z _{eιn of} the ionization chamber 16 after ignition or is conjugate complex adapted.

By means of so-called 3D-RF simulators, the electromagnetic fields and the input resistance Z _eιn can be calculated before the time of ignition of the lamp. Of course, simulators do not take into account high-frequency ionization and ignition. If the changing input resistance Z _{eιn be determined} after ignition, so this is possible via a so-called hot scattering parameter measurement. This is known from the measurement of the electrical properties of power transistors.

The o.g. Frequency hopping can be achieved either with a voltage varying oscillator 18, e.g. in one embodiment as a so-called VCO (voltage controlled oscillator), or implement a fast electronic switching between two fixed oscillators. Since VCOs in the lower GHz range are available at very low cost as modules, they may be preferred. In FIG. 1, the high-frequency oscillator 18 is shown as a switchable high-frequency oscillator 18. This is supplied with a control signal 32. The high-frequency signal 14, ie the output signal of the oscillator 18, which is typically in the mW range, is raised by means of the power amplifier 20 in the one to two-digit W range. Highly integrated electronic power amplifiers 20 in the lower single-digit GHz range have efficiencies of well over 60% and are extremely inexpensive and thus predestined.

In order for the greatest possible voltage to be present in the ionization chamber 16, an impedance transformation is carried out by means of the impedance transformer 26. performed. There is a very wide range of circuits in the HF-FaII. An inexpensive circuit consists of capacitors and coils (multistage gamma transformer) and can be read in "Hochfrequenztechnik" by H. Heuermann, Vieweg-Verlag. The impedance transformer 26 may be implemented in one or more stages. In addition to the high transformation of the impedance level and thus also of the voltage, the circuit comprised by the impedance transformer 26 should also include an adaptation of the electrode 28 of the ionization chamber 16. The output impedance Z _out should preferably be in the two-digit Ω range or in the single-digit kΩ range or higher.

A voltage at the electrode 28 in the ionization chamber 16 is calculated directly from the output power of the amplifier 20 P _out and

^ off

Consequently, an operating point should be chosen so that it lies clearly above the plasma frequency wp.

In order to obtain the best possible efficiency, a preferred embodiment of the invention provides that as little high-frequency power as possible is reflected. For this purpose, a circuit is particularly suitable as shown schematically simplified in FIG 2. The circuit comprised by the signal generating section 12 is activated by the control signal 32 (see also FIG. A processing unit 34 in the manner of a micro-processor sets the high-frequency oscillator 18 to a frequency f _r1 for the ignition operation. A control signal generated by the processing unit 34 or generated by the processing unit 34 is also designated as a control signal 35 to distinguish it from the control signal 32. The generated high-frequency signal 14 is set high in the power via the amplifier 20, passes through a low-loss coupler 36 and passes via the impedance transformer 26 to the electrode 28 of the ionization chamber 16, which holds a gas mixture 24 enclosed by the quartz glass jacket of the glass bulb 22. If the high-frequency lamp 10 ignites, a significantly greater RF power is reflected at the electrode 28. This passes to the coupler 36 and is attenuated via this supplied to a high-frequency detector 38. A thereby changed output signal of the high-frequency detector 38 is received by the processing unit 34, which causes by setting the high-frequency oscillator 18 to the frequency f _r2 a frequency _jump for the Leuchtbe- operation.

For this lighting operation there is the following optimization: The processing unit 34 varies the frequency of the high-frequency signal 14 by the frequency f _r2 by a small positive and a small negative value f _rΔ and outputs a corresponding _actuating signal 35. The reflected powers are measured for three frequency points f _r2 -f _r Δ, fe, fe + frΔ. The value with the lowest reflected power is then the new output value. This rule is repeated throughout. This ensures that as much HF power as possible is always fed into the ionization chamber 16 and converted as little as possible into heat losses.

FIG. 3 shows a preferred embodiment of the high-frequency lamp 10, which is distinguished by a symmetrical structure. The high-frequency oscillator 18 is a low-loss signal divider 40 with a first and second signal divider output 42, 44 downstream. The power amplifier 20 (see FIG 1 or FIG 2) is connected to the first signal divider output 42 is followed by the already described in FIG 1 or FIG 2 circuit components. At the second signal divider output 44, a phase shifting means 46 is connected to which a second power amplifier 48, a second impedance transformer tor 50 and a second electrode 52 are connected in series. The high-frequency signal 14 generated by the high-frequency oscillator 18 is divided by the signal splitter 40, in particular into two equal proportions, ie the high-frequency signal 14 and a second high-frequency signal 14 '.

An "upper" signal path via amplifier 20, transformer 26 up to the first electrode 28 (left) is unchanged from the situation described with reference to FIG. 1 or FIG. In a "lower" signal path is initially as means for phase shift 46, a phase shifter with 180 ° phase rotation, the z. B. can be realized in the form of a 180 ° long line. Thereafter, the antiphase signal is boosted in power by the second amplifier 48 and boosted by the second impedance transformer 50 to be finally supplied to the second electrode 52 (right).

This design has the advantages that the amplification of both amplifiers 20, 48 is simply added without additional circuitry, that the plasma in the ionization chamber 16 is punctiform in the middle and that no mass (see FIG. 1 or FIG the glass bulb 22 must be brought.

This high-frequency lamp 10 with the illustrated control operation can of course also be used in control mode, that is, in an embodiment as shown in FIG 2 and described in connection with it above.

Regardless of the number of impedance transformations (FIG 1, FIG 2: only one impedance transformer 26. FIG 3: two impedance transformers, namely impedance transformer 26 and second impedance transformer 50) in the signal generation, an apparatus for impedance transformation, as shown in FIG. 4, is advantageous. 4 shows, as a lamp head, the ionization chamber 16 of a high-pressure gas discharge lamp 10 (cf., FIG. 1) with the glass bulb 22 and a pressure insulation region 54 (glass lead-through). A short supply line 56, which forms the input of the impedance transformer 26, 50 as it were, can be a pure coaxial line with the characteristic impedance of 50 ohms. These as well as the remainder of this distributed circuit are contained in a circular tube 58 having at the end a cap 60 with bore 62 resembling a washer. This tube 58 forms the ground for this unbalanced distributed circuit and the cap 60 forms the ground for the electrode 28. The supply line 56 is connected to a first and second line bow 64, 66. The first conductor bend 64 is connected to an inner conductor 68 which is arranged in the glass feedthrough 54 and is made of molybdenum, for example. This in turn conducts the high-frequency signal 14 (see FIG. 1) to the electrode 28, which is surrounded by the gas or gas-metal vapor mixture.

In terms of circuit technology, the second line bend 66 is a small inductance connected to ground. The first conductor bend 64 and the inner conductor 68 form a significantly larger inductance. The head part of electrode 28 and associated mass can be described by a small capacitor and a parallel-connected high-impedance load resistor. Consequently, the circuit forms a parallel resonant circuit with coupled inductance. The inductance must be in resonance with the capacitance. The voltage at the coupling point in the region of the beginning of the feed line 56 is markedly transformed up to the electrode 28. This single-stage impedance transformation is very compact, simple and robust. A corresponding one-stage transformatively effective portion comprises at least the supply line 56 and the first and second line bow 64, 66. The direct connection of the inner conductor 68 via the first and second line bow 64, 66 to ground lowers the temperature of the electrode 28. The mechanical structure is stable and compact. However, at very high pressures and / or very low powers, or even to improve the efficiency, multi-stage transformations can offer advantages. Transformations with concentrated components that are known, cf. H. Heuermann: "High-frequency technology", op. Cit., Have relatively poor grades and thus relatively large losses. An embodiment which is even better in this respect is shown in FIG.

The circuit in FIG. 5 differs from the circuit shown in FIG. 4 by a high-impedance design of an extended line section 70 instead of the short supply line 56 previously provided in its place for realizing a series inductance and by a purely capacitive coupling of the extended line section 70 to the line through the Tube 58 formed mass. In addition, two small capacitors 72, 74 result from the first and second line bends 64, 66, because of the line geometry. The latter are two series-connected gamma transformers (see H. Heuermann: "Hochfrequenztechnik", loc. Cit.). The circuit shown in FIG 5 with a multi-stage transforming effective section comprises the extended line section 70, the two capacitors 72, 74 and 64, 66, the first and second line bow 64, 66. A first transformer is by the series inductance of the extended line section 70 and the capacitance connected to ground of one of the capacitors 72 resulting from the conduction geometry. A second transformation The capacitor is formed by the series capacitance 60 of the second capacitor 74 resulting from the conduction of the line, and a grounded inductance 64 of the second conduction arc. The third stage of the impedance transformation is as usual. The advantages of this somewhat more elaborate circuit are higher transformation ratio and wider bandwidth. For both embodiments (FIG. 4 and FIG. 5), the high-frequency signal is transmitted through a shielded waveguide structure (in this case the tube 58), which is formed by the configuration of the inner conductors 56, 64, 66, 68; 70, 64, 66, 68 is formed so that an impedance transformation is included, the glass bulb 22 is supplied. These

Construction has the advantage compared to HF antenna lamps that no RF radiation takes place and the lamp is therefore eligible. Furthermore, the efficiency increases. The HF load (filled glass bulb 22 with a short feedthrough electrode 28) has a very high impedance, which means that when adapted, very large electric field strengths are achieved at low powers.

Cavity modes are well studied scientifically and technically and implemented in many components such as RF filters. From a certain lower, so-called cutoff frequency, these modes can exist. They are very popular in technology because the losses in the metal are very low. FIG. 6 shows a possible cavity mode (E ₀ -ι). This is very interesting for implementation in a high-frequency lamp 10 (FIG. 1, FIG. 2, FIG. 3) for room illumination or for other applications, since the electric field (and thus also the plasma) has the optimal form of a large ball. In the relatively large ionization chamber 16, there are only field lines that propagate only parallel to the ground planes. In addition, these strongest electric fields make a ring that ensures a maximum flare ball. A possible embodiment of the high-frequency lamp 10 (FIG. 1, FIG. 2, FIG. 3) as a cavity resonator lamp 76 (short: HR lamp) for exciting the EorMode is shown in FIG. 7 shows the arrangement for the case in which the HR lamp 76 has been designed in asymmetrical circuit technology (see FIG. 1 or FIG. For both possible circuit techniques, the magnetic field is excited by a loop-shaped electrode 78. In this case, a symmetrical solution (FIG. 3) prevents the occurrence of other unwanted cavity modes much better than the asymmetrical solution. The loop-shaped electrode 78 of the HR lamp 76 is thus only a coupling element for the resonator, which is formed only from the limitation of the possibly slightly metallized surfaces of the glass bulb 22. By means of an adjustable coupling k (see H. Heuermann: "Hochfrequenztechnik", op. Cit.), A voltage transformation can again be performed. This transformation is shown (a weak coupling can be used to create a large transformation) in H. Heuermann: "High-Frequency Technique", op. Cit., As a gamma transformation that slightly detunes the resonance frequency. As the transformation value increases, the bandwidth decreases.

In the case presented of the Eoi mode, the plasma sphere forming in the ionization chamber 16 (region of the largest currents in the plasma) is located only in the cavity and does not contact the loop-shaped electrode 78 (electrodes 78, not shown, in the case of a symmetrical solution according to FIG. 3). still the mass. Of course, the entire content of the ionization chamber 16 is also ionized here. The lonisationsstrecken are to be considered in first approximation as ohmic resistors (consumers). These "reduce" the reactive resonator range, so that frequency hopping may also be useful here. The choice of mode and the geometric design of the electrode has an influence on the maximum plasma region and the resulting input resistance Z _{eιn of} the HR lamp 76. By means of SD-RF field simulators, the electromagnetic fields in the interior of the glass bulb 22 in alignment and the absolute size. The areas of greatest electric field strength are the areas where the largest plasma currents flow. These hottest regions are thus decoupled from the or each electrode 78.

The previous electrode designs referred only to the use of a metallic electrode 28, 52, 78. A very advantageous embodiment of the invention is when, instead of the metallic electrode 28, 52, 78, a purely dielectric electrode or a mixed structure of a metal core and a dielectric sheath is used. If only one dielectric (with a relatively large dielectric constant) is used as the electrode, RF technology refers to the dielectric wire or dielectric resonator. In the case of the dielectric wire, a hybrid fundamental HE ₁₁ is preferably selected as the line mode. Depending on the coupling, further low-loss modes can also be used for the dielectric resonator. In contrast, if a mixed structure of a metal core and a dielectric sheath is used, a Goubauscher surface conductor (also Goubau Harmsscher conductor) is created, which allows a very low-loss transmission in the range of two-digit MHz range to the GHz range.

These two structures (general dielectric electrode), instead of the metallic electrode (s) 28; 52 or acting as a coupling element loop-shaped electrode (s) 78 are used. In this case, the coupling structure of the elements described, for example, in the embodiment according to FIG. 4, namely electrode 28, pressure insulation layer, changes. rich / glass feedthrough 54 and inner conductor 68. Depending on the desired high frequency mode, a wide range of mechanical constructions is applicable. An example of an excitation of the basic mode (which is capable of propagation from OHz) is shown in FIG. 8. Another example is shown in FIG. 9 for the excitation of the Eoi mode whose implementability is very advantageous. The text comprised by FIG. 8 is "HEn wave" and "λ / 2". The text comprised by FIG. 9 is "E _O i wave", "εi = 81 ε ₀ ", "ε ₂ = ε ₀ ", "λ / 2" and "λ = 14.4σ <λ _c = 23 _J 6σ ".

As mentioned, the dielectric electrode can be used instead of another electrode 28, 52, 78 in the HF and HR lamps 10, 76 (FIGS. 1, 2, 3 and 7, respectively). With the HR lamp 76, nothing changes at the waveguide mode. Only the geometric shaping of the dielectric wire has to be optimized according to the coupling-in conditions. Consequently, one proceeds from a coaxial mode to the mode of the dielectric conductor and finally to the ball waveguide mode. Somewhat different is the high-frequency lamp 10. Here changes optically less. For example, FIG. 10 shows a high-frequency lamp 10 which, with the dielectric electrode used, is also referred to as a dielectric lamp, above a mass plate 80 (the glass bulb 22 is not shown) for a point light generation with symmetrical activation from one side, ie with two electrodes 82, 84 in an embodiment that can be implemented by means of purely metallic, mixed or purely dielectric electrode materials. However, a metallic electrode is an LC resonant circuit and a dielectric electrode is a mode of a dielectric resonator. In both cases, the embodiment shown in FIG. 10 produces a glow of a point source which sits between the two electrodes 82, 84. This arrangement is an advantageous embodiment of the high-frequency lamp 10 for high-pressure applications. If, in addition or as an alternative to the measures proposed here for increasing the electric field, the resonator voltage is to be increased even further, this succeeds if a "loaded quality" is improved. DE 10 2004 054 443 (Heuermann, H., Sadeghfam, A., Lünebach, M .: "Resonator system and method for increasing the loaded quality of a resonant circuit") contains a large number of circuit technology solutions that can also be used here , Accordingly, the relevant disclosure content of the above-mentioned DE 10 2004 054 443 is hereby incorporated in its entirety in the description of the invention in the foreground.

In the following, further embodiments or possible embodiments of the invention will be presented, at least cursorily: The use of magnets allows a simple manipulation of the design of the ionization path. After the electrode design, that is, its design in terms of shape and dimension, is basically arbitrary, the high-frequency lamp 10 can also be used as a light source for effective advertising lamps. By means of a suitable frequency selection, different ionization paths can be controlled very quickly, which allows new ways for a lamp design. Among other things, areas with different phosphors (phosphors) and thus also different colors can be ionized. This allows a variant of display devices in the manner of a plasma TV.

Even the classic plasma television concept can be replaced by the RF excitation. Instead of the LF control signals, two push-pull HF control signals can be used. An impedance transformation also allows to achieve high voltages at very low power levels. In addition, currently the three colors of a pixel via 3 x two data lines. In contrast, a frequency division multiplexing method can be used to drive a pixel over only two lines. Among other things, this design would improve the image resolution. In addition to the efficiency, the reaction time of all the plasma-plasma variants mentioned would be improved.

In summary, the present invention can be briefly described as follows: A novel design for the construction of a high frequency lamp 10 for low and high pressure applications and a method for their operation is specified, which is particularly suitable for the properties with respect to To improve the efficiency, emission spectrum, cost and longevity by using an impedance transformer 20 downstream impedance transformer 26, even at very low RF power, the use of an ignition unit is no longer necessary because with the impedance transformation, the application of the highest possible voltage to an ionization chamber 16 succeeds , This high-frequency lamp 10 can be used both as a high-pressure and as a low-pressure gas discharge lamp. Classic starters are not necessary. Depending on the design, the high-frequency lamp 10 has a small punctiform or a large spherical ionization region with large current flows and thus high color temperatures with a coverage of up to several dm ² and allows any adjustment of the light output. This dimming capability and the better light spectrum qualify the high-frequency lamp 10 for interior lighting. The long service life, the daylight spectrum, the low price and the high power compatibility qualify the high-frequency lamp 10 with punctiform high current range for use in devices such as so-called projectors and beamers as well as a motor vehicle headlamp. Excellent efficiencies and highest Color temperatures can be achieved with this high-frequency lamp 10, inter alia, by the use of dielectric electrodes. The high-frequency lamp 10 can be produced very inexpensively by means of high-frequency electronic components, which are very inexpensive due to the telecommunications market, and conventional gas discharge lamp technology, especially since the high voltage requirements are significantly lower compared to conventional starter circuits.

LIST OF REFERENCE NUMBERS

10 high-frequency lamp, 46 phase shift

HF lamp 48 power amplifier

12 Signal generation area 50 Impedance transformer

14 high-frequency signal 52 second electrode

14 'high frequency signal 35 54 pressure isolation area

16 ionization chamber 56 supply line

18 high-frequency oscillator 58 tube

20 power amplifier 60 cap

22 glass bulb 62 bore

24 gas 40 64 first pipe bend

26 impedance transformer 66 second line arc

28 electrode 68 inner conductor

30 ground 70 line piece

32 control signal 72 capacitor

34 Processing unit 45 74 Capacitor

35 control signal 76 cavity resonator lamp,

36 coupler HR lamp

38 high-frequency detector 78 loop-shaped electrode

40 signal divider 80 mass plates

42 Signal divider output 50 82 Electrode

44 Signal divider output 84 Electrode

Claims

claims

1. High-frequency lamp (10) having a signal generating area (12) for generating a high-frequency signal (14) and a downstream ionization chamber (16), wherein the signal generating area (12) comprises a switchable high-frequency oscillator (18) and at whose output a power amplifier (20 ) for raising a power of the high-frequency signal (14), wherein the ionization chamber (16) comprising at least one gas-filled glass bulb (22), at least one electrode (28) is associated and wherein the power amplifier (20) an impedance transformer (26 ) connected at its output to the or each electrode (28).

2. high-frequency lamp (10) according to claim 1, wherein the signal generating portion (12) in addition to the power amplifier (20) downstream, in particular between the power amplifier (20) and impedance transformer (26) arranged coupler (36), a high-frequency detector (38) and a processing unit (34), wherein a in the operation of the high frequency lamp (10) at the electrode (28) reflected high frequency signal via the coupler (36) the high frequency detector (38) can be supplied and wherein a due to an output signal of the high frequency detector (38) of the Processing unit (34) can be supplied as a control signal (35) generatable control signal to the high-frequency oscillator (18) for optimizing the high-frequency signal (14) based on the reflected signal.

3. High-frequency lamp (10) according to claim 1, wherein the high-frequency oscillator (18) a signal divider (40) having a first and second signal divider output (42, 44) connected downstream and the power amplifier (20) at the first signal divider output (42) is connected, wherein second signal divider output (44), a phase shifting means (46), a second power amplifier (48), a second impedance transformer (50) and a second electrode (52) are connected in series.

4. High-frequency lamp (10) according to claim 1 or 2 or according to claim 3, wherein the impedance transformer (26) or the impedance transformer (50) and / or the second impedance transformer (50) comprises a single-stage or multi-stage transforming effective section (56 , 66, 64; 70, 74, 66, 64).

5. High-frequency lamp (10) according to any one of the preceding claims, wherein the or each electrode (28) is dielectric, in particular by a surrounded by a dielectric sheath metal core is formed.

6. High-frequency lamp (10) according to one of the preceding claims with a loop-shaped electrode (78).

7. High-frequency lamp (10) according to one of the preceding claims, wherein the glass bulb (22) is filled with a mixture of at least two gases, in particular exactly three gases, with different emission spectra.

8. High-frequency lamp (10) according to one of the preceding claims, wherein the ionization chamber (16) comprises at least two glass pistons (22), in particular three glass pistons (22), each with a gas are filled with different emission spectra and wherein each glass bulb (22) is associated with an electrode (28) for supplying a high-frequency signal (14).

9. A method for operating a high frequency lamp (10) according to claim 1, wherein the high frequency signal (14) from the high frequency oscillator (18) is generated, wherein the power of the high frequency signal (14) by the downstream power amplifier (20) is increased, wherein the high frequency signal ( 14) is transformed into the high voltage range by the impedance transformer (50) connected downstream of the power amplifier (20), and wherein the transformed high frequency signal (14) is supplied to the electrode (28).

10. The method of claim 9 for operating a high-frequency lamp (10) according to claim 2, wherein the high-frequency detector (38) at an ignition of the high-frequency lamp (10) to the electrode (28) reflected and via the coupler (36) forwarded high-frequency signal detected and wherein the processing unit (34) for optimizing the high-frequency signal (14) adapts the control signal (32) based on the output signal of the high-frequency detector (38), in particular by a predetermined positive or negative value varies and a corresponding control signal (35) based on the control signal (32) and the output signal of the high-frequency detector (38) generated.

11. The method according to any one of claims 9 or 10 for operating a high-frequency lamp (10) according to claim 3, wherein the signal divider (40) from the high-frequency signal (14) a second high-frequency signal (14 '), in particular such that a high-frequency signal (14) remaining high-frequency signal and the second high-frequency signal (14') are at least substantially identical, wherein the means for phase shift (46) the second high-frequency signal (14 ' ), the downstream second power amplifier (48) increases the power of the phase-shifted second high-frequency signal (14 '), and wherein the downstream second impedance transformer (50) transforms the resulting second high-frequency signal (14') in one or more stages and to the second electrode (52).

12. The method of claim 9, 10 or 11, wherein the impedance transformer (26; 50) transforms the high frequency signal in one or more stages.

13. The method according to any one of claims 9 to 12 for operating a high-frequency lamp (10) according to claim 7, wherein the high-frequency oscillator (18) generates at least two high-frequency signals (14) and the at least one electrode (28) are supplied.

14. The method according to any one of claims 9 to 12 for operating a high frequency lamp (10) according to claim 8, wherein the high frequency oscillator (18) generates at least two high frequency signals (14) and fed each high frequency signal (14) exactly one of the at least two electrodes (28) becomes.

15. Display device with a plurality of line and column-shaped arranged high-frequency lamps (10) according to claim 7 or 8.

16. A method of operating a display device according to claim 15, wherein each high frequency lamp (10) is operated by a method according to claim 13 or 14.