CN1914708A - Optical control of light in ceramic arctubes - Google Patents

Abstract

A ceramic arctube preferably for a high pressure discharge lamp. The ceramic arctube can have an anti-reflection interference coating on the outside or inside surface of the bulb section of the arctube. The outside and/or inside surface of the outer wall of the bulb section of the arctube can be substantially spherical to increase efficiency. The wall thickness of the outer wall of the bulb section can be shaped to lens rays from the arc toward a preselected region of a retlector optically coupled to the arctube to increase efficiency.

Description

Light in the optics control ceramic arc tube

The application requires in the U.S. Provisional Application No.60/540 of submission on January 30th, 2004,475 interests, and its content is hereby incorporated by reference.

Technical field

The present invention relates generally to and in lamp, use, relate more specifically to the light of optics control from ceramic arc tube in the high-pressure discharge lamp to produce the ceramic arc tube of light.

Background technology

For example mercury is luminous with the mixture of halogen or metal halide by use the electric arc ionization packing material pass through between two electrodes for high-pressure discharge lamp.Electrode and packing material are sealed in the translucent or transparent arc-shaped cavity or discharge cavity in the electric arc tube, comprise and keep encouraging the pressure of packing material in this electric arc tube and allow the light of emission to pass through.In history, electric arc tube is formed by quartz.Yet in order to improve colour temperature, colour rendering and luminous efficiency, the ceramic arc tube of working been has has been researched and developed in the reaction of minimizing and packing material under higher temperature and pressure simultaneously.Referring to U.S. Patent No. 5,866,982, its content is hereby incorporated by reference.Yet the refractive index of the refractive index ratio quartz of the ceramic material of use is higher, and might be than quartz scattered light more effectively.This makes and to be difficult to control directive and the light by ceramic arc tube.This need improve ceramic arc tube, and the more effective and effective control of the light of its emission is to improve performance.The present invention is exactly at this needs.The present invention has special application in being called short arc discharge lamp, its arc gap is 1mm approximately for example, more generally is applied to produce in any lamp of light beam of good control.

Summary of the invention

A kind of ceramic arc tube that discharge lamp produces electric arc that is used for is provided, and described electric arc tube comprises the ceramic outer wall with spherical part.This electric arc tube also is included in the packing material of arc-shaped cavity inside in the described spherical part and comprises pair of electrodes.This ceramic arc tube has the optics controlling features of the one or more light that are selected from following group: a) at the antireflection interference coatings on the outer surface of described spherical part or on the inner surface; B) outer surface of the outer wall of spherical part or inner surface are spherical basically; And c) wall thickness of spherical part outer wall is configured as from the predetermined selection zone focusing light of circular arc to the reflective mirror that couples light to electric arc tube.

Description of drawings

Fig. 1 is the cross-sectional view according to ceramic arc tube of the present invention;

Fig. 2 is the cross-sectional view that can select embodiment according to ceramic arc tube of the present invention;

Fig. 3 is the cross-sectional view that can select embodiment according to ceramic arc tube of the present invention;

Fig. 4 is the cross-sectional view that can select embodiment according to ceramic arc tube of the present invention;

Fig. 5 is the cross-sectional view that can select embodiment according to ceramic arc tube of the present invention;

Fig. 6 is the cross sectional representation that comprises according to the reflector lamp of ceramic arc tube of the present invention;

Embodiment

As used herein, as given range 5-25 or 5 to 25 time, this expression preferably is at least 5, preferably is no more than 25 for example.

With reference to figure 1, show cross section according to ceramic arc tube 10 of the present invention.Electric arc tube 10 comprises electrode 12,14, outer lead 16,18, electric conducting material body 20,22, cylindrical ceramic shell or outer wall 24 and end plug 26,28.Show antireflection (A/R) thin film interference coatings 30 on the outer surface that is arranged on electric arc tube 10.Ceramic package 24 be around the longitudinal axis by the definition of the longitudinal axis of outer lead 16,18 and electrode 12,14 be shaped cylindrical, shell 24 can have 4-20mm, more preferably the outer dia of 6-10mm.

Ceramic package 24 is polycrystalline Yttrium-Aluminium-Garnet (PC YAG)-Y preferably ₃Al ₅O ₁₂Not too preferred monocrystalline YAG; Not too preferred sapphire (Al ₂O ₃); Not too preferred microcrystalline alumina (MCA); Not too preferred spinelle (MgAl ₂O ₄) or AlON (Al ₂₃O ₂₇N ₅) or Yttrialox (Y ₂O ₃And ZrO ₂) or polycrystal alumina (PCA).The preferred 0.3-3mm of the thickness of ceramic package 24, more preferably 1-2mm, more preferably 1.5-1.6mm.

End plug 26,28 is pottery and preferably identical with shell 24 ceramic material preferably, makes their matched coefficients of thermal expansion.The thickness of end plug 26,28 is identical with the thickness of shell 24 or suitable with the thickness of shell 24.Selectively, this end plug can be not included in the electric arc tube.Outer lead 16,18 is molybdenum or niobium preferably.Electrode the 12, the 14th, refractory metal, preferred tungsten.Electric conducting material body 20,22 cermet (ceramic-metal composites) materials preferably well known in the art or alternatively metallic conductor for example have closely molybdenum axle (mandrel) around volume (preferred molybdenum).The preferred 5-20mm of bulb inside length from surface 32 to surface 34, more preferably 6-15mm, more preferably 8-12mm.Chamber 36 between surface 32 and surface 34 also is called arc-shaped cavity or discharge cavity, and comprises packing material well known in the art.Electric arc tube 10 is a foot in the part of arc-shaped cavity end; Show foot 38.Also show spherical part (bulbsection) 40.

One aspect of the present invention is antireflection (A/R) thin film interference coatings 30 on a kind of outer surface that is coated on electric arc tube 10, is used to compensate because the undesirable high Fresnel reflection from the outer ceramic surface of spherical part 40 that the very high refractive index of pottery causes.The refractive index of common preferably ceramic material is in 1.7 to 1.9 scope, and the refractive index of quartz in visible wavelength region is 1.46.More particularly, the refractive index of YAG is 1.84, and PCA or sapphire refractive index are 1.77.Refractive index is 1.84 o'clock, the inner surface of YAG big envelope or arc-shaped cavity and outer surface all will cause vertical incidence light 8.7% by Fresnel reflection, and each surface of quartz envelope will only cause 3.5% Fresnel reflection.Therefore, each surface of ceramic envelope will cause usually than more much about 5% the Fresnel reflections of traditional quartz envelope, and perhaps 10% Fresnel reflection is more manyed than tradition branch quartz envelope in the big envelope two sides.In needed application, most of Fresnel reflected rays is not easy to be gathered into useful light beam.

In general, Fresnel reflection light reflects towards arc source usually.If light is directly by this arc source, this light will reappear from the arc source as the light beam output light source that comes in handy so.Yet output beam may be lost the Fresnel reflection light of (miss) arc source of any lacking (being positioned at the reflective mirror focus), because it emits from the focus outside of reflective mirror.Therefore, do not comprise typical ceramic arc tube of the present invention 10% more than not too useful light is provided in light beam.

The A/R coating is coated on the Fresnel reflection that can eliminate about 65-90% on the outer surface of ceramic arc tube or the inner surface usually, therefore can reduce about 3-4 percentage point in each surperficial loss, if two surfaces all apply the light beam output variable that A/R has just directly increased about 6-8% thus.As shown in Figure 1, A/R coating 30 can be arranged on the outer surface of shell 24 and end plug 26,28.Selectively, coating 30 can only be arranged on the exterior periphery of shell 24 length directions (not being arranged on the exposed end perpendicular to it), perhaps only on outer wall 24 parts of arc-shaped cavity outside, just, on the outer surface of spherical part 40.Preferably, the outer surface of all or nearly all spherical part and/or inner surface are coated with coating 30.If be coated to inner surface, the A/R coating need only be coated to the circumference of the inner casing length direction between surface 32 and the surface 34.The A/R coating that applies is the interference thin film coating, the preferred tantalates (tantala) that uses in having the alternating layer of silica.Selectively, can use following material to replace tantalates: titanium dioxide, niobium oxide, aluminium oxide, mixed oxide solution is titanium dioxide-tantalates for example, other material perhaps well known in the art.The A/R coating that the A/R coating is preferably traditional, for example being coated on refractive index usually is the coating of glass or the quartz base plate of 1.4-1.5, but this A/R coating should be adjusted according to mode well known in the art, to adapt to 1.7-1.9, common about 1.8 higher index of refraction of ceramic.

A/R coating among the present invention can use any common coating process well known in the art to apply, and preferably uses chemical vapor deposition (CVD), physical vapor deposition (PVD) and evaporation.There are a lot of distortion in these common coating processes series, include but not limited to that metal-organic C VD (MOCVD), plasma-enhanced CVD (PECVD), plasma promote CVD (PACVD), plasma pulse CVD (PICVD), atmospheric pressure cvd (APCVD).Also have similar a large amount of PVD distortion, the overwhelming majority uses sputter material as the coating source.Common vapo(u)rization system uses electron beam for example with fusing and cause that the evaporation in coating material source or ion promote evaporation.Mask process well known in the art can be used for only providing A/R coating on spherical part 40.

Provide the example of an A/R coating on ceramic YAG substrate now, use tantalates and silica.Only apply a side.The layer #1 of direct neighbor substrate is the silica of 160.13nm.Other layer is: layer 2 is tantalates of 12.41nm; Layer 3 is silicas of 18.89nm; Layer 4 is tantalates of 101.45nm; Layer 5 is silicas of 82.37nm.Uncoated YAG substrate has about 17.4% light reflectivity.Have the relevant effect (entitlement) of YAG substrate one side of very good non-reflective coatings with coating the entire emission rate is reduced to about 8.7%.5 layers of structural design with this example, the expection reflectivity is reduced to about 9.4%, its corresponding to the entire emission rate reduce about 41% or effect about 91%.Other A/R coating well known in the art can be used for electric arc tube 10.

In addition, same or analogous A/R coating can be coated on the inner surface of ceramic arc tube 10, preferably for example is coated on the inner surface of the ceramic arc tube with straight cylinder as shown in Figure 1.If use the inner surface of CVD coating processes coated ceramic electric arc tube, aspect ratio (length/inside diameter) should be more preferably less than 10 preferably less than 20 so, with key-course thickness.If this coating is coated on the inboard and the outside of YAG substrate, total reflection will be reduced to approximately 1.4% so, and it reduces 91% corresponding to total reflection.And, can adjust the A/R coated designs to reduce the reflection loss of ultraviolet ray (UV) according to general knowledge known in this field.UV is remained on electric arc tube inside have and reduce the advantage that optical components downstream is exposed to the UV in the light beam, and/or further increase the advantage of arc discharge efficient.A/R coating 30 preferably comprises 2-100, more preferably 3-20, more preferably 3-7 layer.

With reference to figure 2, show the ceramic arc tube identical with electric arc tube 10, except spherical part 42 has ellipse (perhaps alternatively any sag vertical curve) outer surface and inner surface, as shown in the figure, this ellipse outer surface and inner surface are around the focus 44 in the about centre position between the electrode.(well known in the art, this arc is positioned on the focus, this focus between electrode about centre position and be the focus of reflective mirror.) for example, this outer surface and inner surface can be its center under the focus 44 or on circular arc.Benefit is that the more parts of the ray 46,48 that the inner surface of spherical part 42 and outer surface reflect will be returned by focus 44, therefore as useful control beam output composition when comparing with straight cylinder spherical part 40 shown in Figure 1.And, can apply A/R coating 30.But,, be used for the advantage of the curvilinear surface by this arc guiding Fresnel reflected rays even more useful for the ceramic arc tube that is not used in the A/R coating that reduces Fresnel reflection.

With reference to figure 3, show the ceramic arc tube identical with the electric arc tube of Fig. 2, as shown in the figure, except spherical part 50 is to have sphere or spherical haply spherical form, and have concentric outside and the inner surface (when with cross section illustrating it be circular) of their center in focus 52; And, A/R coating 30 is not shown for the sake of brevity, although can apply A/R coating 30.Therefore, Fig. 3 shows the outer surface and the inner surface of the outer wall of sphere or spherical haply spherical part.For the ceramic arc tube of the A/R coating that does not reduce Fresnel reflection, be used for the advantage of the spherical surface that returns by this arc guiding Fresnel reflected rays even more useful.Its benefit is, a lot of or material part that the inner surface of spherical part 50 and outer surface reflect or material part or major part or all haply light 54 will return by focus 52, and therefore be used as the part of useful controlled light beam output.This design is preferred for the design of Fig. 2, and the design of Fig. 2 is preferable over the design of Fig. 1, because more light that the inner surface of spherical part and outer surface reflect return by focus, and as the useful beam output.The inner surface or the outer surface (being not both) of not too preferred spherical part can be the spherical form of center in focus 52.

The electric arc tube of Fig. 2-6 can not have A/R coating 30, but preferably they have aforesaid A/R coating 30.

Fig. 4 shows the ceramic arc tube identical with the electric arc tube of Fig. 1, except the A/R coating is not shown for the sake of brevity, spherical part 56 be thicken as shown in the figure to produce lens component 62, this emission light of its focusing (lens).For example, Fig. 1 show the focus 59 that originates between the electrode about centre position and basically straight line pass the light 58 of ceramic outer wall 24.Yet in Fig. 4, light 64 originates from focus 60 and is focused when its lens component 62 by ceramic outer wall or crooked.By changing wall thickness and lens component 62 being provided, this causes that the light from arc focuses on towards the more preferably zone (for example center of reflective mirror or mid portion) of reflective mirror, focuses on light total amount in the device with increase.In order to realize light focusing, adjust the shape of ceramic outer wall, make the curvature of outer surface greater than the curvature of inner surface, effect resembles or convex lens, line 66 wall thickness maximums under the line, and along with you near foot 68,70 gradually and attenuation smoothly.Therefore, obtain the lens of hope.As shown in Figure 4, the inner surface of spherical part 56 is cylindrical around by the longitudinal axis of the longitudinal axis of electrode definition.

Fig. 5 is identical with Fig. 4's, except having the center and realize lens component 72 in the spherical inside surface 76 of focus 82 and the spherical part 74 of parabola, ellipse or other crooked outer surface 78 by providing.Therefore, the inner surface 76 of spherical part 74 has defined non-cylindrical bulbous shape around the longitudinal axis that the longitudinal axis by electrode defines.As can be seen, provide lens component 72, because along with you walk to foot from equatorial line 80, wall thickness reduces.An advantage of this design is to be reflected back toward focus 82 from the light that spherical inside surface 76 reflects, and therefore as useful beam output, A/R coating 30 can be provided on the outer surface 78 simultaneously, the feasible reflection that reduces or minimize outer surface 78.Selectively, lens component 72 can be provided, its outer surface 78 is its center in the sphere of focus 82 (just basically, be similar to the outer surface 77 among Fig. 3), inner surface 76 is that (a) has the arc than the radius of curvature radius of curvature longer or that quite grow of outer surface 78 simultaneously, thereby lens shape is provided, and perhaps (b) is similar to the oval or shallow curve-like of the inner surface 81 among Fig. 2.The result has provided preferably has smooth arc-shaped outer surface and smooth or smooth arc-shaped inner surface and line is thicker and along with near foot's lens of attenuation gradually under the line.

Foot 84,86 connects or is combined into the part of spherical part 74 therein, and therefore wherein outer wall 88 be combined into the part of lens component 72, preferred wall thickness remains unchanged or is constant basically, make from outer wall 88 to lens component 72 to have level and smooth transition, then lens component 72 thickening gradually as shown in the figure.About lens component 62 and 72, the lens component thickness of line and the ratio of lens component thickness that wherein is combined into foot's outer wall are preferably between 10 and 1.01 under the line, more preferably between 5 and 1.05, more preferably between 3 and 1.1, between 2.5 and 1.3, more preferably be 2 or about 2 more preferably.

With reference to figure 6, show a kind of reflector lamp 92, comprising: the ceramic arc tube 90 suitable with the electric arc tube of Fig. 5, be installed in the reflective mirror 94 well known in the art and with its optical coupling, this reflector lamp 94 is preferably parabola shaped or oval.This shows the advantage of lens component 96; Do not focus on if light 97 is launched out, it will be escaped reflective mirror 94 and disappear in useful beam output.Yet because lens component 96, light 97a is bent or focuses on, and makes its directive reflective mirror 94, is therefore assembled and as useful beam output.Light 98 is also towards the more preferably zone focusing of reflective mirror 94.

The ceramic package of Fig. 1 or outer wall 24 are preferred by the extruding manufacturing; The ceramic package of the electric arc tube of Fig. 2-6 or ceramic outer wall (comprising spherical part) can be made by injection molding well known in the art or slip-casting method or other method.If injection moulding, ceramic package or ceramic outer wall can select to make two symmetrical sheets (along equatorial line 66 or opened in 80 minutes), sintering together then.

Another aspect of the present invention provides the ceramic arc tube of a kind of minimizing from the volume scattering of spherical part.Light scattering in material volume may make light depart from their incident path.The light of scattering may drop on outside the focused beam, and reduces overall performance.Volume scattering in the sintering polycrystalline material is to be caused by the border between residual porosity and the particle, and these particles have 10 to 50 microns size usually.For example quartz or single-crystal ceramic in glassy material, they do not have granule boundary, and are 100% on its density theory, therefore do not have internal void.These materials have effective zero volume scattering.Volume scattering in polycrystalline ceramic can reduce by improving density, reduces hole and internal void thus, perhaps increases particle size reducing amounts of particles, so that particle size is decreased to about 1 micron or littler.

In order to reduce or the minimized volume scattered quantum, ceramic material is sapphire (signle crystal alumina Al preferably ₂O ₃) or monocrystalline Yttrium-Aluminium-Garnet (SC YAG)-Y ₃Al ₅O ₁₂Polycrystalline spinel (PC spinelle)-MgAl not too preferably ₂O ₄Polycrystalline Yttrium-Aluminium-Garnet (PC YAG)-Y not too preferably ₃Al ₅O ₁₂Polycrystal alumina (PCA)-Al not too preferably ₂O ₃In a preferred embodiment, the outer wall of spherical part is made by monocrystalline.

In common application, synthetic Fresnel reflection " R ", the light collection efficiency " e " on the refractive index of these materials " n ", two surfaces illustrate volume scattering and Fresnel reflection loss, are respectively:

1, sapphire: n=1.77; R=15.4%; E=92%

2、SC?YAG：n＝1.84；R＝17.5％；e＝90％

3, PC spinelle: n=1.72; R=14.0%; E=90%

4、PC?YAG：n＝1.84；R＝17.5％；e＝85％

5、PCA：n＝1.77；R＝15.4％；e＝55％

Preferably, the present invention is used for and being connected of lamp, and preferred high-pressure discharge lamp preferably has the control of very short arc gap and point-device beam mode, has following preferred feature.Therefore, light fixture lower and higher wattage has these value predetermined parameter.

1, packing material: mercury, halogen (preferred bromine, not too preferably other halogen), rare gas (preferred argon) and minor amounts of oxygen.Well known in the art, filler does not comprise metal halide in preferred short arc discharge lamp.

2, mercury vapor pressure during operation: 2-600atm, more preferably 5-600atm, more preferably 50-600atm, more preferably 100-400atm, more preferably 200-300atm, more preferably 225-275atm, more preferably about 250atm.

3, add the amount of mercury: 0.01-2mg/mm ³, more preferably 0.05-1.5mg/mm ³, more preferably 0.1-1mg/mm ³, more preferably about 0.5mg/mm ³

4, at distance between electrodes (gap): 0.2-10mm, more preferably 0.2-5mm, more preferably 0.5-2mm, more preferably 0.7-1.3mm, more preferably about 1mm.

5, rated voltage: 30-300V, more preferably 60-120V, more preferably about 75V.

6, rated power: 10-3000W, more preferably 50-500W, more preferably 100-300W, more preferably about 300W.This lamp provides 50-70LPW usually.

7, wall loading (based on the internal surface area of arc-shaped cavity): 0.1-5W/mm ², more preferably 1-3W/mm ², more preferably about 2W/mm ²

8, inside volume of arc chamber: 10-1000mm ³, more preferably 50-300mm ³, more preferably about 200mm ³

9, for quartzy short-arc lamp, the diameter of electrode, shape and size are well known in the art; Referring to U.S. Patent No. 5,357,167,5,109,181 and 5,497,049.Its content is hereby incorporated by reference.Preferably, shank diameter is 0.1-1mm, preferred 0.3-0.5mm, preferred about 0.5mm; Preferred diameter is 0.3-5mm, more preferably 1-2mm, more preferably about 2mm.

If 10 use bromine in filler, the addition of bromine is preferably 10 ^-12To 10 ^-7Mole/mm ³, more preferably about 10 ^-11To 10 ^-9Mole/mm ³If use other halogen, measure similar.

The preferred purposes of the present invention is to be used for the short arc ceramic arc tube of video projecting lamp, to be used for automobile, optical fiber, display, medical science, scientific equipment equally, in the high intensity discharge lamp apparatus.Other commerce is applied as in any lamp product that requires good control beam (high brightness, low dazzle the eyes etc.) when using that uses pottery or high-performance electric arc tube.The present invention can also be used for the high temperature incandescent halogen, and wherein this application need has the succinct littler overcoat of transparent ceramic electric arc tube, and the succinct electrodeless high intensity discharge with transparent ceramic electric arc tube.The present invention also is applied in all high-pressure discharge lamps with ceramic arc tube, preferred high-pressure mercury lamp (not comprising metal halide), not too preferred high-pressure mercury-metal halide lamp (comprising mercury and metal halide) and high-voltage metal-halide lamp (not comprising mercury in the filler) can be used for incandescent halogen and electrodeless high intensity discharge lamp equally.

Though described the present invention with reference to preferred embodiment, those skilled in the art should understand that and to carry out various variations without departing from the scope of the invention and its element is equal to replacement.In addition, under the prerequisite that does not break away from its essential scope, many modifications can be carried out so that special case or material adapt to instruction of the present invention.Therefore, the present invention is not limited to conduct and is used to carry out the disclosed specific embodiment of best mode for carrying out the invention, but the present invention will comprise all embodiment that fall in additional claims scope.

Claims (17)

1, a kind of ceramic arc tube that is used for discharge lamp generation electric arc, described electric arc tube comprises: the ceramic outer wall with spherical part, described electric arc tube also is included in the packing material of arc-shaped cavity inside in the described spherical part, and described ceramic arc tube has the optics controlling features of the one or more light that are selected from following group:

A) at the antireflection interference coatings on the outer surface of described spherical part or on the inner surface;

B) outer surface of the outer wall of spherical part or inner surface are spherical basically; And

C) wall thickness of the outer wall of spherical part is configured as from the predetermined selection zone focusing light of circular arc to the reflective mirror that couples light to described electric arc tube.

2, the electric arc tube of claim 1, wherein said electric arc tube have at the outer surface of spherical part or the antireflection interference coatings on the inner surface.

3, the electric arc tube of claim 2, wherein said electric arc tube have the described antireflection interference coatings on the basic whole outer surface that is coated in spherical part.

4, the electric arc tube of claim 1, wherein the outer surface of the outer wall of spherical part or inner surface are spherical basically.

5, the electric arc tube of claim 4, wherein the outer surface of the outer wall of spherical part is spherical basically.

6, the electric arc tube of claim 4, wherein the inner surface of the outer wall of spherical part is spherical basically.

7, the electric arc tube of claim 5, wherein the inner surface of the outer wall of spherical part is spherical basically.

8, the electric arc tube of claim 1, wherein the wall thickness of the outer wall of spherical part is configured as from the predetermined selection zone focusing light of circular arc to the reflective mirror that couples light to described electric arc tube.

9, the electric arc tube of claim 8, wherein the inner surface of spherical part is cylindrical for what be shaped around the longitudinal axis by the definition of the longitudinal axis of electrode.

10, the electric arc tube of claim 8, wherein the inner surface of spherical part defines non-cylindrical bulbous shape around the longitudinal axis that the longitudinal axis by electrode defines.

11, the electric arc tube of claim 8, wherein the outer surface of the outer wall of spherical part is spherical basically.

12, the electric arc tube of claim 8, wherein the inner surface of the outer wall of spherical part is spherical basically.

13, the electric arc tube of claim 12, wherein said electric arc tube have the described antireflection interference coatings on the basic whole outer surface of spherical part.

14, the electric arc tube of claim 1, wherein the outer wall of spherical part is made by monocrystal material.

15, the electric arc tube of claim 1, wherein said electric arc tube is arranged in the video projecting lamp.

16, the electric arc tube of claim 15, described electric arc tube also comprises pair of electrodes.

17, the electric arc tube of claim 4, wherein the outer wall of spherical part is made by the material that is selected from the group of being made up of sapphire, monocrystalline Yttrium-Aluminium-Garnet and polycrystalline Yttrium-Aluminium-Garnet.

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