26.2: Controlled Electrodes in UHP Lamps

Moench, Holger; Deppe, Carsten; Hechtfischer, Ulrich; Heusler, Gero; Pekarski, Pavel

doi:10.1889/1.1821416

Cited by 10 publications

(9 citation statements)

References 4 publications

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“…It is interesting to note that short rectangular current pulses have already been used for controlling the spot mode of arc attachment in UHP lamps [21,22]. However, the pulses employed in [21,22] were used to add current to the electrode and took place at the end of the anodic phase, i.e., were substantially different from those employed in this work, and served a different objective, namely, to facilitate appearance of a protrusion on the electrode surface. On the other hand, this attests to the technical viability of the spot prevention method proposed in this work.…”

Section: Prevention Of Transient Spotsmentioning

confidence: 99%

Formation of stationary and transient spots on thermionic cathodes and its prevention

Almeida¹,

Benilov²,

Cunha³

2008

J. Phys. D: Appl. Phys.

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Spots on cathodes of high-pressure arc discharges induced by a rapid increase in the arc current are studied numerically and experimentally. Appearance of stationary and transient spots is analysed in the context of the general pattern of steady-state modes of current transfer to thermionic cathodes and their stability. Transient spots are studied in experiments with COST-529 standard lamps. Modelling and experimental results are in reasonable agreement. A method to prevent formation of transient spots on cathodes of high-pressure arc discharges by means of short negative rectangular current pulses is proposed and validated both numerically and experimentally. Experimental indications are found that the main mechanism of blackening of burners of HID lamps that accompanies appearance of transient cathode spots is evaporation of the cathode material and not sputtering.

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Section: Prevention Of Transient Spotsmentioning

confidence: 99%

Formation of stationary and transient spots on thermionic cathodes and its prevention

Almeida¹,

Benilov²,

Cunha³

2008

J. Phys. D: Appl. Phys.

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“…A long-life lamp requires electrodes with a very stable shape: the electrode tip should not recede (burn-back) or move laterally, owing to evaporation and transport of tungsten. These phenomena depend mainly on the temperature of the electrode [24,27]. Therefore, long-life electrode design aims at controlling electrode temperature.…”

Section: Electrode Designmentioning

confidence: 99%

“…More detailed criteria can be deduced from systematic life tests of lamps with known electrode temperatures, flanked by model simulations [24]. Figure 14 shows the measured electrode temperature in a 250 W UHP lamp.…”

Section: Electrode Designmentioning

confidence: 99%

UHP lamp systems for projection applications

Derra¹,

Moench²,

Fischer³

et al. 2005

J. Phys. D: Appl. Phys.

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Projection systems have found widespread use in conference rooms and other professional applications during the last decade and are now entering the home TV market at a considerable pace. Projectors as small as about one litre are able to deliver several thousand screen lumens and are, with a system efficacy of over 10 lm W −1 , the most efficient display systems realized today. Short arc lamps are a key component for projection systems of the highest efficiency for small-size projection displays. The introduction of the ultra high performance (UHP) lamp system by Philips in 1995 can be identified as one of the key enablers of the commercial success of projection systems. The UHP lamp concept features outstanding arc luminance, a well suited spectrum, long life and excellent lumen maintenance. For the first time it combines a very high pressure mercury discharge lamp with extremely short and stable arc gap with a regenerative chemical cycle keeping the discharge walls free from blackening, leading to lifetimes of over 10 000 h. Since the introduction of the UHP lamp system, many important new technology improvements have been realized: burner designs for higher lamp power, advanced ignition systems, miniaturized electronic drivers and innovative reflector concepts. These achievements enabled the impressive increase of projector light output, a remarkable reduction in projector size and even higher optical efficiency in projection systems during the last years. In this paper the concept of the UHP lamp system is described, followed by a discussion of the technological evolution the UHP lamp has undergone so far. Last, but not least, the important improvements of the UHP lamp system including the electronic driver and the reflector are discussed.

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“…Following its launch, the UHP-lamp system has been improved with a fast innovation rate. [4][5][6][7][8][9][10][11][12][13][14] Many important new technology improvements have been realized: burner designs for higher lamp power, advanced ignition systems, miniaturized electronic drivers, and innovative reflector concepts. These achievements enabled the impressive increase of light output from the projector, a remarkable reduction of projector size, and an even higher optical efficiency of projection systems during the last several years (see Fig.…”

Section: Introductionmentioning

confidence: 99%

Invited Paper: UHP‐lamp systems for projection applications

Pollmann‐Retsch¹,

Mönch²,

Baier³

et al. 2007

J Soc Info Display

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Abstract— Projection systems have found widespread use in conference rooms and other professional applications during the last decade and are now entering the home‐TV market with considerable pace. Projectors as small as about one liter are nowadays able to deliver a screen flux of several thousand lumens and are, with a system efficacy of more than 10 lm/W, the most‐efficient display system realized today. Because such highly efficient projectors employ microdisplays as light valves, short‐arc lamps are a key component in realizing these properties. The introduction of the UHP‐lamp system by Philips in 1995 can be identified as one of the key enablers for the commercial success of projection systems. The ultra‐high‐performance (UHP) lamp concept features outstanding arc luminance, a well‐suited spectrum, long life, and excellent flux maintenance. For the first time, it combines a very‐high‐pressure mercury‐discharge lamp having an extremely short and stable arc length with a regenerative chemical cycle that keeps the discharge walls free from blackening, leading to lifetimes of over 10,000 hours. In this review, the most important aspects of the UHP concept that enabled its success in the projection market are described, followed by a discussion of some recent additions to the UHP‐product portfolio.

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26.2: Controlled Electrodes in UHP Lamps

Cited by 10 publications

References 4 publications

Formation of stationary and transient spots on thermionic cathodes and its prevention

Formation of stationary and transient spots on thermionic cathodes and its prevention

UHP lamp systems for projection applications

Invited Paper: UHP‐lamp systems for projection applications

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