CA1255746A - Single-ended metal halide discharge lamps and process of manufacture - Google Patents
Single-ended metal halide discharge lamps and process of manufactureInfo
- Publication number
- CA1255746A CA1255746A CA000455936A CA455936A CA1255746A CA 1255746 A CA1255746 A CA 1255746A CA 000455936 A CA000455936 A CA 000455936A CA 455936 A CA455936 A CA 455936A CA 1255746 A CA1255746 A CA 1255746A
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- CA
- Canada
- Prior art keywords
- envelope
- electrodes
- metal halide
- metal
- elliptical
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
- H01J9/24—Manufacture or joining of vessels, leading-in conductors or bases
- H01J9/245—Manufacture or joining of vessels, leading-in conductors or bases specially adapted for gas discharge tubes or lamps
- H01J9/247—Manufacture or joining of vessels, leading-in conductors or bases specially adapted for gas discharge tubes or lamps specially adapted for gas-discharge lamps
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/02—Details
- H01J61/04—Electrodes; Screens; Shields
- H01J61/06—Main electrodes
- H01J61/073—Main electrodes for high-pressure discharge lamps
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J61/00—Gas-discharge or vapour-discharge lamps
- H01J61/82—Lamps with high-pressure unconstricted discharge having a cold pressure > 400 Torr
- H01J61/827—Metal halide arc lamps
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- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Discharge Lamp (AREA)
- Vessels And Coating Films For Discharge Lamps (AREA)
- Manufacture Of Electron Tubes, Discharge Lamp Vessels, Lead-In Wires, And The Like (AREA)
- Discharge Lamps And Accessories Thereof (AREA)
- Developing Agents For Electrophotography (AREA)
- Projection Apparatus (AREA)
Abstract
SINGLE-ENDED METAL HALIDE DISCHARGE LAMPS AND
PROCESS OF MANUFACTURE
ABSTRACT
A single-ended metal halide discharge lamp including a fuse silica elliptical-shaped envelope which is filled with a metal halide dosed high pressure mercury fill and wherein a pair of electrodes each having a metal rod with a ball on the end thereof are sealed whereby isothermal operation of the elliptical-shaped envelope is effected. A manufacturing process is also provided wherein an elliptical-shaped envelope is formed, a pair of electrodes having metal rods with a ball on the end thereof are sealed into one end of the envelope, and the envelope is filled with a metal halide dosed high pressure mercury fill.
PROCESS OF MANUFACTURE
ABSTRACT
A single-ended metal halide discharge lamp including a fuse silica elliptical-shaped envelope which is filled with a metal halide dosed high pressure mercury fill and wherein a pair of electrodes each having a metal rod with a ball on the end thereof are sealed whereby isothermal operation of the elliptical-shaped envelope is effected. A manufacturing process is also provided wherein an elliptical-shaped envelope is formed, a pair of electrodes having metal rods with a ball on the end thereof are sealed into one end of the envelope, and the envelope is filled with a metal halide dosed high pressure mercury fill.
Description
35'i'~6 srNGLE-~NDED METAL HALIDE DISC~RGE LAMPS AND
PR~CESS OF M~NUFACTURE
CROSS REFERENCE TO OTHER APPLICA~IONS
The following concurrently filed Canadian patent applications relate to single-ended metal halide discharge lamps and the ~abrication thereof: g55.934-~; ~55,933-~; 455,932-1; and 455,9~5-5.
TECHN r CAL FIELD
This inven~ion relates to single-ended me-tal halide discharge lamps and the manufacture of such lamps and more paLticularly to single-ended meta~ halide discharge lamps having a stabili~ed arc and an envelope formed for isothermal operation.
BAC~GROU~D OF q'HE INVENTION
rn the field of projectors. optical lens systems and similar applications requiring a relatively intense source of light, it has been a common practice tO employ a light source in the form of a tungsten lamp. Although tungsten or tungsten halogen lamps do have certain desirable features such as low cost~ desirable color features enhancing skin tones and do not require a special power source, several undesirable features are unfortunately also present. For example, structures employing a tungsten source do not generate enough blue light, ~end to undesiLably generate large amounts of heat which necessitates expensive and cumbeLsome cooling D-83-1-0~8 devices located adjacent the light source, and ten~ to exhibit a relatively short life such as an operatlonal period of about 10 to 20 hours. Thus, it is not uncommon to replace the li~ht source each time the appa~atus is employed. Obviously, such inconvenience and e2pense leaves much to be desired. ~oreover, screen illuminatlon is limited due to the inability to increase surface luminance much beyond 3400 K while the mechanical body structure ls rigid leading to destruction during operation by chemical means and by vibration or shock.
An improvement over the above-described system is provided by the use of metal halide discharge lamps as a light sourcs. For e2ample, a common form of high pressure metal halide discharge lamp is disclosed in U.S. Patent No. 4,161,672. Thereln, a double-ended arc tube or an arc tube having electrodes sealed into diametrically opposite ends is employed in conjunction with an evacuated or noble gas filled outer envelope. However, it has been found that such structures are relatively expensive to manufacture and are obviously not appropriate for use in projectors or other optlc lens-type appartus.
As to single-ended metal halide arc discharge lamps, U.S. Patent Nos. 4,302,699; 4,308,483; 4,320,322; 4,321,501 and 4,321,504 all dlsclose variations in structure or flll suitable to a particular application. However, any one or all of the above-mentioned patents leave something to be deslred lnsofar as stabllity of the arc and lsothermal uniformity of the dlscharge lamp are concerned.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the present lnventlon is to provide an Improved single-ended high intensity discharge lamp. Another object of the invention is to enhance the capabilitles of single ended hlgh intenslty discharge lamps. Still another object of the inventlon ls D-83-1-05~
to provide a single-ended high intensity discharge lamp having an improved structural configuration. A further ob~ect of the invention is to provide an improved process for manufacturing sin~le-ended hi~h intensity discharge lamps.
-5 ~ ~ These and other objects, advantages and cspabilities are achieved in one aspect of the invention by a slngle-ended high pressure hi~h intensity discharge lamp having a pair of electrodes each including a metal rod with a spherical ball on the end thereof sealed into and passing through one end of sn elliptical-shaped envelope of fused silica containing a metal-bearln~ mercury fill therein.
In another aspect of the invention, a process for manufacturlng single-ended metal halide discharge lamps is provided wherein a pair of electrodes each ha~ing a spherical ball on the end o~ a metal rod are sealed into one end of an elliptical-shaped fused slllca envelope, and the envelope is filled with unsaturated metal-be~ring mercury.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of one embodiment of a sln~le-ended hi8h intensity dlscharge lamp of the inventiOD
FIG. 2 is a diagrammatic illustration of the discharge and convect1On gas flow for Yertlcal operation of the dischar~e lamp of FIG. l;
FIG. 3 is another illustration of the dlscharge lamp of FIG. 1 showing the approximate electric field lines of force between the electrodes of the lamp; and FIG. 4 is a photograph, 100 X enlargement, of an electrode of the embodiment of FIG. 1.
11-83-1-058 i;~S5~7~6 .
_4 BEST MODE FOR CARRYING OUT THE INYENTION
For a better understanding of the present inventlon, together with other and further objects, advantages and capabilltles thereof, "~ ~
- reference ls made to the ~ollowing dlsclosure and appended clalms ln connection wlth the accompanying drawings.
Re~errlng to the drawlngs, FIG. 1 illustrates a low wattage metal halide lamp having a body portlon 5 oÇ a materlal such as fused silica. This fused sllica body portion 5 ls formed to provlde an elllptlcal-shaped lnterior portlon 7 having a ma~or and minor diametrlcal measurement, "X" and "Y" respectlvely, in a ratio of about 2:1. Moreover, the elllptlcal-shaped interior portlon 7 preferably has a helght "Z" substantially equal to the mlnor dimenslonal measurement "Y~.
Sealed lnto one end o~ and passing through the body portlon 5 ls 15 a palr of electrodes 9 and 11. Each of the electrodes 9 and 11 includes a metal rod 13 with a spherlcal ball 15 on the end thereof wlthln the elllptlcal-shaped lnterior portlon 7. Preferably, the electrodes 9 and 11 are posltioned wlthin the elllptlcal-shaped lnterlor portion 7 in a manner such that the end o~ the spherlcal 20 balls 15 o~ the electrodes 9 and 11 15 substantlally equally spaced from the interlor portlon 7 lnsofar as the ma~or and mlnor axes "~"
and "Y" and slso substantlQlly at the mldpolnt of the height "Z".
~lso, a metal-bearing mercury fill ls disposed withln the elllptical-shaped interior portlon 7. For example, mercury dosed 25~ with a metal hallde such as sodlum and scandlum along wlth argon ls an approprlate flll for a low wattage metal hallde dlscharge lamp.
Speciflcally, ~ S0-watt discharge lamp having an elllptical-shaped lnterlor portlon 7 wlth a volume o~ about .1 Cm3 was ~111Qd with about 3.0 mgms of mercury, 1.9 mgms of sodlum and scandium ln a molar ratlo of about 20:1 and argon at a pressure of about 200 D-83-1-058 ~ ~ ~ S 7 i~
torr. Oper~tional testin~ provided an initial lumen output of about 3100 lumens with a lumen maintenance of about 84% after 160 hours o~
operational life.
Referring more speciÇically to the above-described elllptical-shaped lnterior portion 7, FIG. 2 of the drawin~s illustrates the electrodes 9 and 11 each having a spherical ball 15 thereon and spaced along the major a~is "X" and substantlally equal dlstance from the walls 17 of the interior portlon 7. As can readily be seen, the body portion S is preferably vertlcally positloned such that the spherical balls 15 are located one above the other. As a result, a ~as flow pattern ls provlded, as lndlcated by the arrows, wherein cool ~as tends to flow down the outslde wall 17 of the interior portion 7 and is drawn into the elliptical-shaped arc or plasma column 22 at the bottom electrode 11. The spherical ball 15 of the bottom electrode 11 provldes a spherical extension, which will be explained hereinaEter, and~ in turn, produces gas flow pinching or a venturi action 20 at the arc terminus of the spherical ball 15 of the bottom electrode 11. In thls manner, arc terminus wanderln~ is minimlzed. Also, the gas atoms are heated in the plasma column 22, and the upper electrode 9 acts as a deflector which spreads the hot gases reaching the top of the body portion 5 of the elliptical-shaped arc tube. Moreover, infrared measurements oÇ the temperature oÇ the wall 17 during operation of the arc tube lndicate less than a 20~ te~perature variation at a wall temperature of about 1100~ C. Thus, the above-described elliptical-shaped interior portion 7 and the elliptical-shaped arc 22 provlde a convection current flow; 21 of FIG. 2, which is substantially uniform and free from undesired turbulence such that arc stability, which is particularly lmportant in projectors and lens systems, ls provided.
'7 ~
Additionally, lt has been noted that the above-described arc tends to wander about the contact re~lon of the spherical balls 15 initlally. Howsver, lt has been Eound that the employlng of a seasoning step in the manufacturing process tends to cause deYelopment of protuberances 24 of (FIG. 4) on each one of the bQlls 15. As a result, the protuberances 24tend to minimize the arc gap between the spherical balls 15 of the electrodes g and 11 and force the arc to have centrally located terminatlon points on each of the electrodes ~ and 11.
0 Although not completely understood, it ls believed that the above-described protuberances 24 of (FIG. 4) are o a size which depends upon the local materlal properties and the field stren~th and eas flow properties. Moreover, the growth formation also appears to be a function of the electrode size and temperature.
Thus, the lower the operating temperature the lon~er the seasoning time requirad.
As a specific example, a 0.017-inch tungsten rod having a ball 15 thereon of about 0.025-inch was operated in a 100-watt metal halide filled dlscharge lamp drawing about 1.6 amperes of current.
After about 15 minutes of "seasoning" at normal operational conditions, it was found that ths arc stabillzed and one or more protuberances appeared on the surface of the spherical balls 15 o~
the electrodes 9 and 11. Thus, the surface brea~up into platelets and formatlon o~ the protuberances on the spheroid balls 15 inhiblts any wanderlng of the arc and enhances the llght source.
Additionally, it is to be noted that an arc source, such as a metal halide discharge lamp, provldes not only higher luminance but also hl~her efflcacy than a tungsten source. Also, 8 mPtal halide dlscharge lamp provides a point source relatlve to a tungsten source. Speciflcally, a 100-watt metal halide dlscharge lamp exihibits a plssma having a minlmum lumlnance intermediate the spherical balls 15 and a maximum luminance at or near the spherical S'i~
balls 15. ~oreover, the plasma column is normally about 1 to 2 mm in diameter and about 3 mm ln length. However, a tun~sten source ls about 2.5 mm in diameter and 8 mm ln length with the luminance varyln~ ln a sinusoidal manner over the len~th of the tungsten ~;~ source.
Following is a table, Table I, showing a comparison ln lumlnance, efficacy and size of a tungsten source, a high pressure xenon source and a metal halide lamp source:
TABLE I
0 Size Theoretlcal Luminance Efficacy (Len~th ~Throu~hPut (Cd~mm) (Lumens~Watt) Diam.)(Lumens) Tungsten 30 33 8 2 2.5 1980 (300 Watts) Xenon 150 20 2.2 g 5 ~00 (150 Watts) Metal Halide Lamp 75 65 3 ~ } 1300 ~100 WBttS) As can readily be seen, the tungsten source at 300 watts provldes about 33 lumens per watt as compared with 65 L/W for a 100-watt metal halide lamp. Also, tests in a 35 mm projectlon system lndicate an output of about 10,000 ~umens from the 300-watt tungsten source is equivalent to that of the 6,500 lumens from the 100-watt metal halide lamp source. The lon~ wavelenth radlatlon snd th~ m~sdlrected visible light of the tungsten source tends to be absorbed as heat by the fllm of a pro~ector. Thus, 15 has been found that the tun~sten lamp ~enerates about 270 watts of heat as compared to about 90 watts or about lJ3 thereof by the metal hallde lsmp snd sssoclated power supply.
~5~7~L6 Further, the ~enon source shows a relatively high luminance capability but a relatively low efficacy capability. Thus, n lumen output of the xenon source which ls comparable to that provided by a 100-watt metal halide lamp would necessitate a xenon source of about 200 watts in order to compensate for a relatively poor ef~lcacy capability. ~oreover, a xenon source has a relatively small diameter, about 0.5 mm in the example, as compared with a metal halide lamp, about 1.0 mm, which greatly and undesirably reduces the tolerances or variations in positioned location of the arc source 0 when employed with a reflector in a projection system. In other words, positional adjustment of an arc source in a xenon lamp is much more critical than in a metal halide discharge lamp system.
Accordin~ly, a sin~le-ended metal halide discharge lamp has been provided wherein electrodes are disposed within an elliptical-shaped interior portion of a fused silica envelope. This elliptical-shaped envelope interior, in conjunction with an elliptical-shaped arc therein, provides a substantially isothermal operational conditlon of the fused silic8 envelope forming the discharge lamp. Moreover, lt has been found possible to provide a stabilized arc which is particularly important in the operatlon of pro~ector and optic lens apparatus.
While there has been shown and described what is at present considered the preerred embodiments of the invention, it will be obvlous to those skilled in the art that various changes and modlflcations may be made therein without departing from the invention as defined by the appended clalms.
PR~CESS OF M~NUFACTURE
CROSS REFERENCE TO OTHER APPLICA~IONS
The following concurrently filed Canadian patent applications relate to single-ended metal halide discharge lamps and the ~abrication thereof: g55.934-~; ~55,933-~; 455,932-1; and 455,9~5-5.
TECHN r CAL FIELD
This inven~ion relates to single-ended me-tal halide discharge lamps and the manufacture of such lamps and more paLticularly to single-ended meta~ halide discharge lamps having a stabili~ed arc and an envelope formed for isothermal operation.
BAC~GROU~D OF q'HE INVENTION
rn the field of projectors. optical lens systems and similar applications requiring a relatively intense source of light, it has been a common practice tO employ a light source in the form of a tungsten lamp. Although tungsten or tungsten halogen lamps do have certain desirable features such as low cost~ desirable color features enhancing skin tones and do not require a special power source, several undesirable features are unfortunately also present. For example, structures employing a tungsten source do not generate enough blue light, ~end to undesiLably generate large amounts of heat which necessitates expensive and cumbeLsome cooling D-83-1-0~8 devices located adjacent the light source, and ten~ to exhibit a relatively short life such as an operatlonal period of about 10 to 20 hours. Thus, it is not uncommon to replace the li~ht source each time the appa~atus is employed. Obviously, such inconvenience and e2pense leaves much to be desired. ~oreover, screen illuminatlon is limited due to the inability to increase surface luminance much beyond 3400 K while the mechanical body structure ls rigid leading to destruction during operation by chemical means and by vibration or shock.
An improvement over the above-described system is provided by the use of metal halide discharge lamps as a light sourcs. For e2ample, a common form of high pressure metal halide discharge lamp is disclosed in U.S. Patent No. 4,161,672. Thereln, a double-ended arc tube or an arc tube having electrodes sealed into diametrically opposite ends is employed in conjunction with an evacuated or noble gas filled outer envelope. However, it has been found that such structures are relatively expensive to manufacture and are obviously not appropriate for use in projectors or other optlc lens-type appartus.
As to single-ended metal halide arc discharge lamps, U.S. Patent Nos. 4,302,699; 4,308,483; 4,320,322; 4,321,501 and 4,321,504 all dlsclose variations in structure or flll suitable to a particular application. However, any one or all of the above-mentioned patents leave something to be deslred lnsofar as stabllity of the arc and lsothermal uniformity of the dlscharge lamp are concerned.
OBJECTS AND SUMMARY OF THE INVENTION
An object of the present lnventlon is to provide an Improved single-ended high intensity discharge lamp. Another object of the invention is to enhance the capabilitles of single ended hlgh intenslty discharge lamps. Still another object of the inventlon ls D-83-1-05~
to provide a single-ended high intensity discharge lamp having an improved structural configuration. A further ob~ect of the invention is to provide an improved process for manufacturing sin~le-ended hi~h intensity discharge lamps.
-5 ~ ~ These and other objects, advantages and cspabilities are achieved in one aspect of the invention by a slngle-ended high pressure hi~h intensity discharge lamp having a pair of electrodes each including a metal rod with a spherical ball on the end thereof sealed into and passing through one end of sn elliptical-shaped envelope of fused silica containing a metal-bearln~ mercury fill therein.
In another aspect of the invention, a process for manufacturlng single-ended metal halide discharge lamps is provided wherein a pair of electrodes each ha~ing a spherical ball on the end o~ a metal rod are sealed into one end of an elliptical-shaped fused slllca envelope, and the envelope is filled with unsaturated metal-be~ring mercury.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of one embodiment of a sln~le-ended hi8h intensity dlscharge lamp of the inventiOD
FIG. 2 is a diagrammatic illustration of the discharge and convect1On gas flow for Yertlcal operation of the dischar~e lamp of FIG. l;
FIG. 3 is another illustration of the dlscharge lamp of FIG. 1 showing the approximate electric field lines of force between the electrodes of the lamp; and FIG. 4 is a photograph, 100 X enlargement, of an electrode of the embodiment of FIG. 1.
11-83-1-058 i;~S5~7~6 .
_4 BEST MODE FOR CARRYING OUT THE INYENTION
For a better understanding of the present inventlon, together with other and further objects, advantages and capabilltles thereof, "~ ~
- reference ls made to the ~ollowing dlsclosure and appended clalms ln connection wlth the accompanying drawings.
Re~errlng to the drawlngs, FIG. 1 illustrates a low wattage metal halide lamp having a body portlon 5 oÇ a materlal such as fused silica. This fused sllica body portion 5 ls formed to provlde an elllptlcal-shaped lnterior portlon 7 having a ma~or and minor diametrlcal measurement, "X" and "Y" respectlvely, in a ratio of about 2:1. Moreover, the elllptlcal-shaped interior portlon 7 preferably has a helght "Z" substantially equal to the mlnor dimenslonal measurement "Y~.
Sealed lnto one end o~ and passing through the body portlon 5 ls 15 a palr of electrodes 9 and 11. Each of the electrodes 9 and 11 includes a metal rod 13 with a spherlcal ball 15 on the end thereof wlthln the elllptlcal-shaped lnterior portlon 7. Preferably, the electrodes 9 and 11 are posltioned wlthin the elllptlcal-shaped lnterlor portion 7 in a manner such that the end o~ the spherlcal 20 balls 15 o~ the electrodes 9 and 11 15 substantlally equally spaced from the interlor portlon 7 lnsofar as the ma~or and mlnor axes "~"
and "Y" and slso substantlQlly at the mldpolnt of the height "Z".
~lso, a metal-bearing mercury fill ls disposed withln the elllptical-shaped interior portlon 7. For example, mercury dosed 25~ with a metal hallde such as sodlum and scandlum along wlth argon ls an approprlate flll for a low wattage metal hallde dlscharge lamp.
Speciflcally, ~ S0-watt discharge lamp having an elllptical-shaped lnterlor portlon 7 wlth a volume o~ about .1 Cm3 was ~111Qd with about 3.0 mgms of mercury, 1.9 mgms of sodlum and scandium ln a molar ratlo of about 20:1 and argon at a pressure of about 200 D-83-1-058 ~ ~ ~ S 7 i~
torr. Oper~tional testin~ provided an initial lumen output of about 3100 lumens with a lumen maintenance of about 84% after 160 hours o~
operational life.
Referring more speciÇically to the above-described elllptical-shaped lnterior portion 7, FIG. 2 of the drawin~s illustrates the electrodes 9 and 11 each having a spherical ball 15 thereon and spaced along the major a~is "X" and substantlally equal dlstance from the walls 17 of the interior portlon 7. As can readily be seen, the body portion S is preferably vertlcally positloned such that the spherical balls 15 are located one above the other. As a result, a ~as flow pattern ls provlded, as lndlcated by the arrows, wherein cool ~as tends to flow down the outslde wall 17 of the interior portion 7 and is drawn into the elliptical-shaped arc or plasma column 22 at the bottom electrode 11. The spherical ball 15 of the bottom electrode 11 provldes a spherical extension, which will be explained hereinaEter, and~ in turn, produces gas flow pinching or a venturi action 20 at the arc terminus of the spherical ball 15 of the bottom electrode 11. In thls manner, arc terminus wanderln~ is minimlzed. Also, the gas atoms are heated in the plasma column 22, and the upper electrode 9 acts as a deflector which spreads the hot gases reaching the top of the body portion 5 of the elliptical-shaped arc tube. Moreover, infrared measurements oÇ the temperature oÇ the wall 17 during operation of the arc tube lndicate less than a 20~ te~perature variation at a wall temperature of about 1100~ C. Thus, the above-described elliptical-shaped interior portion 7 and the elliptical-shaped arc 22 provlde a convection current flow; 21 of FIG. 2, which is substantially uniform and free from undesired turbulence such that arc stability, which is particularly lmportant in projectors and lens systems, ls provided.
'7 ~
Additionally, lt has been noted that the above-described arc tends to wander about the contact re~lon of the spherical balls 15 initlally. Howsver, lt has been Eound that the employlng of a seasoning step in the manufacturing process tends to cause deYelopment of protuberances 24 of (FIG. 4) on each one of the bQlls 15. As a result, the protuberances 24tend to minimize the arc gap between the spherical balls 15 of the electrodes g and 11 and force the arc to have centrally located terminatlon points on each of the electrodes ~ and 11.
0 Although not completely understood, it ls believed that the above-described protuberances 24 of (FIG. 4) are o a size which depends upon the local materlal properties and the field stren~th and eas flow properties. Moreover, the growth formation also appears to be a function of the electrode size and temperature.
Thus, the lower the operating temperature the lon~er the seasoning time requirad.
As a specific example, a 0.017-inch tungsten rod having a ball 15 thereon of about 0.025-inch was operated in a 100-watt metal halide filled dlscharge lamp drawing about 1.6 amperes of current.
After about 15 minutes of "seasoning" at normal operational conditions, it was found that ths arc stabillzed and one or more protuberances appeared on the surface of the spherical balls 15 o~
the electrodes 9 and 11. Thus, the surface brea~up into platelets and formatlon o~ the protuberances on the spheroid balls 15 inhiblts any wanderlng of the arc and enhances the llght source.
Additionally, it is to be noted that an arc source, such as a metal halide discharge lamp, provldes not only higher luminance but also hl~her efflcacy than a tungsten source. Also, 8 mPtal halide dlscharge lamp provides a point source relatlve to a tungsten source. Speciflcally, a 100-watt metal halide dlscharge lamp exihibits a plssma having a minlmum lumlnance intermediate the spherical balls 15 and a maximum luminance at or near the spherical S'i~
balls 15. ~oreover, the plasma column is normally about 1 to 2 mm in diameter and about 3 mm ln length. However, a tun~sten source ls about 2.5 mm in diameter and 8 mm ln length with the luminance varyln~ ln a sinusoidal manner over the len~th of the tungsten ~;~ source.
Following is a table, Table I, showing a comparison ln lumlnance, efficacy and size of a tungsten source, a high pressure xenon source and a metal halide lamp source:
TABLE I
0 Size Theoretlcal Luminance Efficacy (Len~th ~Throu~hPut (Cd~mm) (Lumens~Watt) Diam.)(Lumens) Tungsten 30 33 8 2 2.5 1980 (300 Watts) Xenon 150 20 2.2 g 5 ~00 (150 Watts) Metal Halide Lamp 75 65 3 ~ } 1300 ~100 WBttS) As can readily be seen, the tungsten source at 300 watts provldes about 33 lumens per watt as compared with 65 L/W for a 100-watt metal halide lamp. Also, tests in a 35 mm projectlon system lndicate an output of about 10,000 ~umens from the 300-watt tungsten source is equivalent to that of the 6,500 lumens from the 100-watt metal halide lamp source. The lon~ wavelenth radlatlon snd th~ m~sdlrected visible light of the tungsten source tends to be absorbed as heat by the fllm of a pro~ector. Thus, 15 has been found that the tun~sten lamp ~enerates about 270 watts of heat as compared to about 90 watts or about lJ3 thereof by the metal hallde lsmp snd sssoclated power supply.
~5~7~L6 Further, the ~enon source shows a relatively high luminance capability but a relatively low efficacy capability. Thus, n lumen output of the xenon source which ls comparable to that provided by a 100-watt metal halide lamp would necessitate a xenon source of about 200 watts in order to compensate for a relatively poor ef~lcacy capability. ~oreover, a xenon source has a relatively small diameter, about 0.5 mm in the example, as compared with a metal halide lamp, about 1.0 mm, which greatly and undesirably reduces the tolerances or variations in positioned location of the arc source 0 when employed with a reflector in a projection system. In other words, positional adjustment of an arc source in a xenon lamp is much more critical than in a metal halide discharge lamp system.
Accordin~ly, a sin~le-ended metal halide discharge lamp has been provided wherein electrodes are disposed within an elliptical-shaped interior portion of a fused silica envelope. This elliptical-shaped envelope interior, in conjunction with an elliptical-shaped arc therein, provides a substantially isothermal operational conditlon of the fused silic8 envelope forming the discharge lamp. Moreover, lt has been found possible to provide a stabilized arc which is particularly important in the operatlon of pro~ector and optic lens apparatus.
While there has been shown and described what is at present considered the preerred embodiments of the invention, it will be obvlous to those skilled in the art that various changes and modlflcations may be made therein without departing from the invention as defined by the appended clalms.
Claims (3)
1. A process for manufacturing a single-ended metal-halide discharge lamp comprising the steps of:
(a) forming an elliptical shaped fused silica envelope;
(b) sealing a pair of electrodes into said single end of said elliptical shaped envelope with each of said electrodes having a metal rod passing through said envelope and an spherical ball on the end of each metal rod within said envelope;
(c) filling said elliptical shaped envelope with a metal halide dosed high pressure mercury fill; and (d) seasoning said discharge lamp for a time and at a temperature sufficient to cause development of protuberances on said spherical balls of said electrodes.
(a) forming an elliptical shaped fused silica envelope;
(b) sealing a pair of electrodes into said single end of said elliptical shaped envelope with each of said electrodes having a metal rod passing through said envelope and an spherical ball on the end of each metal rod within said envelope;
(c) filling said elliptical shaped envelope with a metal halide dosed high pressure mercury fill; and (d) seasoning said discharge lamp for a time and at a temperature sufficient to cause development of protuberances on said spherical balls of said electrodes.
2. A process as described in Claim 1 wherein said step of forming said elliptical shaped fused silica envelope is performed such that said elliptical shape has major and minor axes of a ratio of about 2:1 respectively.
3. In a process for manufacturing a single-ended metal-halide discharge lamp having an elliptical shaped envelope wherein a pair of electrodes, each electrode having a metal rod with a spherical ball thereon, is sealed into said single end of said envelope and a metal-halide dosed high pressure mercury fill is dispensed into said envelope, the improvement comprising the step of seasoning said discharge lamp for a time and at a temperature sufficient to cause development of protuberances on said spherical balls of said electrodes.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US50277283A | 1983-06-09 | 1983-06-09 | |
| US502,772 | 1983-06-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1255746A true CA1255746A (en) | 1989-06-13 |
Family
ID=23999352
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000455936A Expired CA1255746A (en) | 1983-06-09 | 1984-06-05 | Single-ended metal halide discharge lamps and process of manufacture |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0128553B1 (en) |
| JP (1) | JPS609048A (en) |
| CA (1) | CA1255746A (en) |
| DE (2) | DE128553T1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01161660A (en) * | 1987-12-17 | 1989-06-26 | Toshiba Corp | Metal halide lamp |
| US4998036A (en) * | 1987-12-17 | 1991-03-05 | Kabushiki Kaisha Toshiba | Metal vapor discharge lamp containing an arc tube with particular bulb structure |
| JP2630642B2 (en) * | 1988-11-28 | 1997-07-16 | 東芝ライテック株式会社 | Small metal halide lamp |
| JP2583129B2 (en) * | 1989-08-23 | 1997-02-19 | 株式会社小糸製作所 | Discharge bulb manufacturing method |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1463056A (en) * | 1973-01-19 | 1977-02-02 | Thorn Lighting Ltd | Electric discharge lamp |
| NL175480C (en) * | 1974-06-12 | 1984-11-01 | Philips Nv | ELECTRODE FOR A DISCHARGE LAMP, METHOD FOR MANUFACTURING SUCH ELECTRODE AND DISCHARGE LAMP PROVIDED WITH SUCH ELECTRODE. |
| NL7514124A (en) * | 1975-12-04 | 1977-06-07 | Philips Nv | PROCEDURE FOR AGING A GAS DISCHARGE LAMP. |
| US4170746A (en) * | 1977-12-27 | 1979-10-09 | General Electric Company | High frequency operation of miniature metal vapor discharge lamps |
| US4275329A (en) * | 1978-12-29 | 1981-06-23 | General Electric Company | Electrode with overwind for miniature metal vapor lamp |
| US4254356A (en) * | 1979-04-23 | 1981-03-03 | General Electric Company | Inlead and method of making a discharge lamp |
| JPS57165945A (en) * | 1981-03-24 | 1982-10-13 | Sylvania Electric Prod | Metal halide arc discharge lamp |
| GB2103872A (en) * | 1981-07-22 | 1983-02-23 | Gen Electric Co Plc | Electric discharge lamp seals |
| US4415829A (en) * | 1981-08-13 | 1983-11-15 | Gte Products Corporation | Direct current operable arc lamp |
-
1984
- 1984-06-05 CA CA000455936A patent/CA1255746A/en not_active Expired
- 1984-06-08 EP EP84106570A patent/EP0128553B1/en not_active Expired
- 1984-06-08 DE DE1984106570 patent/DE128553T1/en active Pending
- 1984-06-08 DE DE8484106570T patent/DE3480889D1/en not_active Expired - Fee Related
- 1984-06-08 JP JP59116812A patent/JPS609048A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0542770B2 (en) | 1993-06-29 |
| DE128553T1 (en) | 1985-04-11 |
| JPS609048A (en) | 1985-01-18 |
| EP0128553B1 (en) | 1989-12-27 |
| EP0128553A1 (en) | 1984-12-19 |
| DE3480889D1 (en) | 1990-02-01 |
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| Date | Code | Title | Description |
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| MKEX | Expiry |