CA1130361A - High pressure sodium vapor discharge lamp with outside starting aid conductor - Google Patents
High pressure sodium vapor discharge lamp with outside starting aid conductorInfo
- Publication number
- CA1130361A CA1130361A CA337,048A CA337048A CA1130361A CA 1130361 A CA1130361 A CA 1130361A CA 337048 A CA337048 A CA 337048A CA 1130361 A CA1130361 A CA 1130361A
- Authority
- CA
- Canada
- Prior art keywords
- high pressure
- conductor
- tube
- discharge lamp
- sodium vapor
- 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
Links
Landscapes
- Discharge Lamps And Accessories Thereof (AREA)
Abstract
ABSTRACT
A high pressure sodium vapor discharge lamp, characterized in that its discharge tube contains xenon gas at a high pressure of e.g. over 150 torr, at least one of the discharge electrodes has a projection conductor which is disposed extending therefrom towards an inside surface of a side wall of a tube envelope of the discharge tube in a manner that the outer end of the projection conductor is disposed in proximity to a side wall of said tube envelope with a predetermined gap inbetween and a starting aid conductor is disposed lengthwise on the outside surface of the side wall, and connected to the other electrode.
A high pressure sodium vapor discharge lamp, characterized in that its discharge tube contains xenon gas at a high pressure of e.g. over 150 torr, at least one of the discharge electrodes has a projection conductor which is disposed extending therefrom towards an inside surface of a side wall of a tube envelope of the discharge tube in a manner that the outer end of the projection conductor is disposed in proximity to a side wall of said tube envelope with a predetermined gap inbetween and a starting aid conductor is disposed lengthwise on the outside surface of the side wall, and connected to the other electrode.
Description
Background of the Invention Field of the Invention:
The present invention relates to an improvement in a high pressure sodium vapor discharge lamp which comprises a translucent gas-discharge tube having therein sodium, buffer gas and xenon gas.
Description of the Prior Art:
Generally speaking, high pressure sodium vapor discharge lamps are about twice as efficient as conventional high pressure mercury lamps and have a comfortable color appearance. Such lamps are attracting attention as energy saving light sources to replace the high pressure mercury lamps. In the discharge tube of a conventional high pressure sodium vapor discharge lamp, xenon gas is sealed -to have a pressure of about 20 Torr, as a starting gas having a low thermal conductivity. As a result of the addition of xenon gas, the starting voltage of the high - pressure sodium vapor discharge lamp may be as high as about 2KV, which is very high in comparison with less than 200V of the mercury lamp. Recently, a high efficiency, high pressure sodium vapor discharge lamp has been proposed, wherein xenon is filled at a pressure of over 150 Torr, for example, 350 Torr, thereby raising lamp efficiency by about 10% than lamps having ,. ~ . . . .
, .
13~
xenon gas at a pressure of about 20 Torr, have been proposed.
In such lamps with high pressure xenon gas, the starting voltage of the lamp is further raised, for example, to about 8-9KV for a high pressure sodium vapor discharge lamp having xenon gas filled with a pressure of 350 Torr. In such a lamp, the start-ing voltage can be lowered to about 3.5KV for a 360W high pressure sodium discharge lamp when utilizing a starting aid wire, but such voltage of 3.5KV is still too high for actual use and liable to cause breakdown of the insulation in the ballast and related lamp circuit.
Summary of the Invention An object of the present invention is to provide a high pressure sodium vapor discharge lamp filled with a very high pressure xenon gas but having a low starting voltage to provide a lamp set not subject to breakdown of insulation.
Another object of the present invention is attained by utilizing a starting aid conductor formed lengthwise on the outside wall of a discharge tube thereof and also a projection of a conductor which is disposed extending from an electrode thereof towards the tube wall and connected to one electrode.
In accordance with the present invention, a starting voltage of the high pressure sodium vapor discharge lamp having a high pressure xenon gas can be reduced to a low voltage of 3KV or lower.
The present invention relates to an improvement in a high pressure sodium vapor discharge lamp which comprises a translucent gas-discharge tube having therein sodium, buffer gas and xenon gas.
Description of the Prior Art:
Generally speaking, high pressure sodium vapor discharge lamps are about twice as efficient as conventional high pressure mercury lamps and have a comfortable color appearance. Such lamps are attracting attention as energy saving light sources to replace the high pressure mercury lamps. In the discharge tube of a conventional high pressure sodium vapor discharge lamp, xenon gas is sealed -to have a pressure of about 20 Torr, as a starting gas having a low thermal conductivity. As a result of the addition of xenon gas, the starting voltage of the high - pressure sodium vapor discharge lamp may be as high as about 2KV, which is very high in comparison with less than 200V of the mercury lamp. Recently, a high efficiency, high pressure sodium vapor discharge lamp has been proposed, wherein xenon is filled at a pressure of over 150 Torr, for example, 350 Torr, thereby raising lamp efficiency by about 10% than lamps having ,. ~ . . . .
, .
13~
xenon gas at a pressure of about 20 Torr, have been proposed.
In such lamps with high pressure xenon gas, the starting voltage of the lamp is further raised, for example, to about 8-9KV for a high pressure sodium vapor discharge lamp having xenon gas filled with a pressure of 350 Torr. In such a lamp, the start-ing voltage can be lowered to about 3.5KV for a 360W high pressure sodium discharge lamp when utilizing a starting aid wire, but such voltage of 3.5KV is still too high for actual use and liable to cause breakdown of the insulation in the ballast and related lamp circuit.
Summary of the Invention An object of the present invention is to provide a high pressure sodium vapor discharge lamp filled with a very high pressure xenon gas but having a low starting voltage to provide a lamp set not subject to breakdown of insulation.
Another object of the present invention is attained by utilizing a starting aid conductor formed lengthwise on the outside wall of a discharge tube thereof and also a projection of a conductor which is disposed extending from an electrode thereof towards the tube wall and connected to one electrode.
In accordance with the present invention, a starting voltage of the high pressure sodium vapor discharge lamp having a high pressure xenon gas can be reduced to a low voltage of 3KV or lower.
- 2 -:, ';
3(~
In one form, the present invention provides a high pressure sodium vapor discharge lamp comprising an outer bulb enclosing a discharge tube in an evacuated space therein, said discharge tube comprising a translucent and chemically stable tube envelope of alumina containing therein sodium , xenon gas, a buffer gas which is at least one member selected from the group consisting of mercury and cadmium and discharge electrodes sealed in both end parts of said tube envelope, in which at least one of said discharge electrodes has a projection conduc- -tor which is disposed extending therefrom towards and in proxi-mity to an inside surface of a side wall of said tube envelope with a predetermined gap inbetween and tha-t a starting aid conductor is disposed lengthwise on the outside surface of said side wall in a manner to face the outer end part of said projec--tion conductor via said side wal]., said starting aid conductor having a connection which impresses a potential substantially identical to that of the other discharge electrode.
Brief Explanation of the Drawing FIG. 1 is a plan view of a discharge tube of a high pressure sodium vapor discharge lamp without a projection of conductor at its electrodes.
FIG. 2 is a sectional elevation yiew of the lamp shown in FIG. 1.
FIG. 3 is a graph showing the relation between distances "f" from the end tip of an electrode to the end tip of a start-ing aid conductor and starting voltages for D.C~ operations of the discharge tube of FIGs. 1 and 2.
~, . . . ~
. ; ' ' . . . .
.. . .
', '' , . 1~3(~63L
FIG. 4 is an enlarged fragmental elevation vie~7 of a discharge tube of a high pressure sodium vapor discharge lamp embodying the present invention.
FIG. 5 is a side view of a high pressure sodium vapor discharge lamp in accordance with the present invention, wherein the discharge tube 100 shown in FIG. 4 is sealed in an evacuated glass bulb 21.
FIG. 6 is a graph showing the relation between gap "d"
from the end tip of a conductor protrusion 9 of an electrode 6 to the inside surface of a tube wall of the discharge tube of FIG. 4 and starting voltages for D.C. operations of the lamp of FIGs. 4 and 5.
FIG. 7 is a circuit diagram of the lighting apparatus utilizing the lamp of FIG. 5.
- 3a -l3 ~
~' ' " . ' ~
1~3(~;~6~
Description of the Preferred Embodiment A high pressure sodium vapor discharge lamp in accordance with the present invention comprises an outer bulb enclosing a discharge tube in an evacuated space therein, said discharge tube comprising a translucent and chemically stable tube envelope con-taining therein sodium, xenon gas, a buffer gas which is at least one member selected from the group consisting of mercury and cadmium, and discharge electrodes sealed in both end parts of said tube envelope, and is characterized in that at least one of said discharge electrodes has a projection conductor which is disposed extending therefrom towards and in proximity to an inside surface of a side wall of said tube envelope with a pre-determined gap inbetween and that a starting aid conductor is disposed lengthwise on the outside surface of said side wall in a manner to face outer end part of said projection conductor via said side wall, said starting aid conductor having a connection which impresses a potential substantially identical to that of the other discharge electrode.
The inventors made many experiments concerning starting characteristics of high pressure sodium vapor discharge lamps having xenon gas filled therein as a starting gas. As a result of the experimental study, the inventors found that a starting voltage of the lamp can be lowered by a large margin, by pro~
viding a protrusion of a conductor (metal) extending from either one of the electrodes towards the inside surface of the side wall of the tube envelope, providing a starting aid conductor stripe (wire) on the outside surface of said side wall and applying ..
' ~13(~
a potential which is substantially identical to that of the other electrode, on the starting aid conductor. The present invention is made in accordance with the abovementioned finding.
The e~periments leading to the present invention and the details of the example of the present invention are elucidated referring to the accompanying drawings. As shown in FIG. 1 and FIG. 2, the discharge tube, which is to be disposed in an evacu-ated outer glass bulb, has a translucent tube envelope 1 of a polycrystalline alumina ceramic tube or a single crystal aluminum tube and a pair of electrodes 6 and 7. The electrodes 6 and 7 are made of tungsten coils, carry an electron-emitting substance therein and are disposed in and near both ends of the tube enve-lope 1 by supportings by lead-in wires 4 and 5 of niobium tubes, which penetrate and are fixed to end caps 2 and 3. In the tube envelope 1 is sealed sodium as light emitting substance, mercury as a buffer gas and xenon as a starting rare gas. A starting aid conductor stripe 8 made of a molybdenum wire of 0.8mm diameter is disposed on the outer surface of the wall oE the tube envelope 1 and is connected to one electrode terminal 5.
The inventors made experiments to study how the starting voltage of the discharge tube changes as one end "b" of the start-ing aid conductor 3 changes its position with respect to one electrode 7, while the other end "a" is fixed substantially to the end of the tube envelope 1 and electrically connected to the other electrode 6, so that potential of the other electrode 7 is im-pressed to the starting aid conductor 8. FIG. 3 shows curves .~ .
, ~3(~
showing relation between a distance "f" from the end tip of the electrode 6 to the end tip of the starting aid conductor 8 and starting voltages (a D.C. voltage is used for the experiment).
The parameters 350 Torr, 250 Torr and 20 Torr of these curves are pressures of xenon gas filled in the tube envelope 1. As shown by FIG. 3, it is found that the starting voltage becomes smallest when the end tip of the starting aid conductor 8 nears most to the electrode 6 and further becomes to face or overlaps with side wall 1 inbetween. As a conclusion, it is found that the starting voltage is dependent on the distance "f" between the end tip of the starting aid conductor 8 and the end tip of the electrode 6, and the starting voltage becomes lower as the distance "f" becomes shorter.
By using an alumina discharge tube, which has an inner diameter of 7.4mm, a tube thickness of 0.7mm and a distance of 83mm between the electrodes, and is for a 360W high pressure sodium vapor discharge lamp, such further experiments are made that a projection conductor 9 is formed to extend from the elec-trode 6 as shown in FIG. 4, and the starting voltages are measured for various gaps "d" between the end tip of the projection con-ductor 9 and the inside surface "e" of the -tube wall 1. A molyb-denum rod of 0.7mm diameter is used as the projection conductor 9 and is fixed to a stem part of the tungsten coil of the electrode 6 by spot welding. FIG. 5 is a side view of a high pressure sodium vapor discharge lamp in accordance with the present invention, wherein the discharge tube 100 shown in FIG. 4 is sealed in an evacuated glass bulb 21. FIG. 6 shows results of the e~periments, .
~ . i , 3~)~6~
which, in comparison with the curves of FIG. 3, show a drastic improvement of the starting voltage by the provision of the projection conductor 9.
Similar experiments were made for the lamps of various wattages, and similar results were obtained. Especially for high power lamps of 700W and lOOOW, the starting voltages are remarkably lowered. This can be elucidated that, in such high power lamps, wherein the gap "d" between the end surface of the electrode and the inside surface "e" of the tube wall 1 is large and hence a providing of only a starting aid conductor 8 on the outside surface of the tube wall 1 does not remarkably lower the starting voltage, such providing of the projection conductor 9 extending towards the starting aid conductor 8 can effectively raise the potential gradient in the gap.
An example manufactured embodying the present invention is as follows:
tube input power................................. 360W -discharge tube 1: inner diameter................. 7.4mm thickness of tube............. 0.7mm inter-electrode distance...... 83mm material....... single crystal alumina electrodes 6 and 7: outer diameter of coil....... 3.6mm starting aid conductor 8: molybdenum wire of..... 0.8mm projection conductor 9: molybdenum wire of....... 0.7mm distance l'd".................................... 0.5mm .
: ~ :
, ~ , , ,, ~
~:~3(~
sealed gas: sodium ......................... 4.5mg mercury ........................ 20mg xenon gas ..................... 350 Torr The starting aid conductor ~ is connected to the electrode 7 through a bimetal switch 10 as shown in FIG. 7, which is made open by means of a high temperature o~ the dis-charge tube 1, in order to disconnect the s~arting aid conductor 8 from the opposite electrode 7 after ignition to prevent loss of sodium from the discharge tube due to unnecessary connection of the starting aid conductor 8 to the opposite electrode 7.
The circuit of the lamp of this example is shown in FIG. 7, wherein commercial A.C. current is fed through a single choke ballast 14 for conventional 400W mercury lamp into the high pressure sodium vapor discharge lamp 15 in accordance with the present invention, wherein,in the bulb 21 or in the stem 22, are provided a bimetal starter switch 12, a series resistor 11, a 3000 pF ceramic capacitor 13 and the bimetal switch 10. As -shown in FIG. 7, the capacitor 13 and a series connection of the resistor 11 and the switch 12 are connected in parallel across the terminals 4 and 5 of the discharge tube, so that the lamp 15 can be started by known producing of a kick voltage by the choke coil 14. The series resistor 11 is to limit the cut-off current of the blmetal starter switch 1~ to the value of 0.5A and also serves to make the bimetal starter switch 12 open by a joule heat thereof. The capacitor 13 is for control-ling to suppress a producing of an extraordinary high kick ,, . ., .~ ,, .
,- . , .. . ..
... .. , .. ,. . ~,., ~, .. .
' ~
6~
voltage and also to shape the kick voltage pulse to have a necessary pulse width. Namely, the capacitor 13 serves to protect the lamp apparatus from insulation breakdown damage and also assure certainty of starting. Tests show that the starting voltage for the 360W lamp of the abovementioned example is about 2KV, and on the other hand, average value of induced high voltages across the terminals of the discharge tube 100 is about 2.5KV, which is sufficiently higher than the starting voltage of the lamp, and therefore the lamps are started with a high lo certainty. Furthermore, on account of lowness of the induced high voltage in the lamp apparatus in comparison with the con-ventional high pressure sodium vapor discharge lamps, there have been no insulation breakdowns of ~allast and circuit during burning tests of the lamps.
Another example of 630W lamp is made by embodying the present invention and with similar details of the deslgn except the following changes:
the inner diameter of polycrystalline - alumina discharge tube ............. 9.7mm the inter-electrode distance ............ 130mm distance "d" ............................ 0.5mm The abovementioned 630W lamp example has such low starting voltage as almost equal to that of the abovementioned example of 360W lamp, while starting voItage of a 630W lamp having similar making but no projection conductor 9 has a starting voltage of 4.5KV, that is higher by about l.OKV than .
,. ~
~3(~6~L
that of the above~entioned 360T~ lamp. The abovementioned 630r,~
lamp can be certainly and stably started by utilizing conventional single choke ballast for 700W mercury lam?.
It has been confirmed that the shape of the projection conductor 9 need not necessarily be in a rod shape, but can be shaped in a ring or a disk. The importance of the projection conductor 9 is that the distance "d" between the inner surface "e" of the tube wall 1 and the outer end of the projection conductor 9 is in a range of certain short distance. The dis-tance "d" should be from 0.3mm to 0.7mm. When the distance "d"is longer than 0.7mm, the lowering of starting voltage is not satisfactory. On thè other hand, when the distance "d" is shorter than 0.3mm, due to smallness of the gap7every igniting discharges always concentrates in a very small area, and hence the very small area is likely to receive an undesirable elfect, thereby inducing a high possibility of making cracks of the tube envelope. Tests show that the optimun distance is between o.4mm ~o 0.6mm.
....
-~., . . , ., -
In one form, the present invention provides a high pressure sodium vapor discharge lamp comprising an outer bulb enclosing a discharge tube in an evacuated space therein, said discharge tube comprising a translucent and chemically stable tube envelope of alumina containing therein sodium , xenon gas, a buffer gas which is at least one member selected from the group consisting of mercury and cadmium and discharge electrodes sealed in both end parts of said tube envelope, in which at least one of said discharge electrodes has a projection conduc- -tor which is disposed extending therefrom towards and in proxi-mity to an inside surface of a side wall of said tube envelope with a predetermined gap inbetween and tha-t a starting aid conductor is disposed lengthwise on the outside surface of said side wall in a manner to face the outer end part of said projec--tion conductor via said side wal]., said starting aid conductor having a connection which impresses a potential substantially identical to that of the other discharge electrode.
Brief Explanation of the Drawing FIG. 1 is a plan view of a discharge tube of a high pressure sodium vapor discharge lamp without a projection of conductor at its electrodes.
FIG. 2 is a sectional elevation yiew of the lamp shown in FIG. 1.
FIG. 3 is a graph showing the relation between distances "f" from the end tip of an electrode to the end tip of a start-ing aid conductor and starting voltages for D.C~ operations of the discharge tube of FIGs. 1 and 2.
~, . . . ~
. ; ' ' . . . .
.. . .
', '' , . 1~3(~63L
FIG. 4 is an enlarged fragmental elevation vie~7 of a discharge tube of a high pressure sodium vapor discharge lamp embodying the present invention.
FIG. 5 is a side view of a high pressure sodium vapor discharge lamp in accordance with the present invention, wherein the discharge tube 100 shown in FIG. 4 is sealed in an evacuated glass bulb 21.
FIG. 6 is a graph showing the relation between gap "d"
from the end tip of a conductor protrusion 9 of an electrode 6 to the inside surface of a tube wall of the discharge tube of FIG. 4 and starting voltages for D.C. operations of the lamp of FIGs. 4 and 5.
FIG. 7 is a circuit diagram of the lighting apparatus utilizing the lamp of FIG. 5.
- 3a -l3 ~
~' ' " . ' ~
1~3(~;~6~
Description of the Preferred Embodiment A high pressure sodium vapor discharge lamp in accordance with the present invention comprises an outer bulb enclosing a discharge tube in an evacuated space therein, said discharge tube comprising a translucent and chemically stable tube envelope con-taining therein sodium, xenon gas, a buffer gas which is at least one member selected from the group consisting of mercury and cadmium, and discharge electrodes sealed in both end parts of said tube envelope, and is characterized in that at least one of said discharge electrodes has a projection conductor which is disposed extending therefrom towards and in proximity to an inside surface of a side wall of said tube envelope with a pre-determined gap inbetween and that a starting aid conductor is disposed lengthwise on the outside surface of said side wall in a manner to face outer end part of said projection conductor via said side wall, said starting aid conductor having a connection which impresses a potential substantially identical to that of the other discharge electrode.
The inventors made many experiments concerning starting characteristics of high pressure sodium vapor discharge lamps having xenon gas filled therein as a starting gas. As a result of the experimental study, the inventors found that a starting voltage of the lamp can be lowered by a large margin, by pro~
viding a protrusion of a conductor (metal) extending from either one of the electrodes towards the inside surface of the side wall of the tube envelope, providing a starting aid conductor stripe (wire) on the outside surface of said side wall and applying ..
' ~13(~
a potential which is substantially identical to that of the other electrode, on the starting aid conductor. The present invention is made in accordance with the abovementioned finding.
The e~periments leading to the present invention and the details of the example of the present invention are elucidated referring to the accompanying drawings. As shown in FIG. 1 and FIG. 2, the discharge tube, which is to be disposed in an evacu-ated outer glass bulb, has a translucent tube envelope 1 of a polycrystalline alumina ceramic tube or a single crystal aluminum tube and a pair of electrodes 6 and 7. The electrodes 6 and 7 are made of tungsten coils, carry an electron-emitting substance therein and are disposed in and near both ends of the tube enve-lope 1 by supportings by lead-in wires 4 and 5 of niobium tubes, which penetrate and are fixed to end caps 2 and 3. In the tube envelope 1 is sealed sodium as light emitting substance, mercury as a buffer gas and xenon as a starting rare gas. A starting aid conductor stripe 8 made of a molybdenum wire of 0.8mm diameter is disposed on the outer surface of the wall oE the tube envelope 1 and is connected to one electrode terminal 5.
The inventors made experiments to study how the starting voltage of the discharge tube changes as one end "b" of the start-ing aid conductor 3 changes its position with respect to one electrode 7, while the other end "a" is fixed substantially to the end of the tube envelope 1 and electrically connected to the other electrode 6, so that potential of the other electrode 7 is im-pressed to the starting aid conductor 8. FIG. 3 shows curves .~ .
, ~3(~
showing relation between a distance "f" from the end tip of the electrode 6 to the end tip of the starting aid conductor 8 and starting voltages (a D.C. voltage is used for the experiment).
The parameters 350 Torr, 250 Torr and 20 Torr of these curves are pressures of xenon gas filled in the tube envelope 1. As shown by FIG. 3, it is found that the starting voltage becomes smallest when the end tip of the starting aid conductor 8 nears most to the electrode 6 and further becomes to face or overlaps with side wall 1 inbetween. As a conclusion, it is found that the starting voltage is dependent on the distance "f" between the end tip of the starting aid conductor 8 and the end tip of the electrode 6, and the starting voltage becomes lower as the distance "f" becomes shorter.
By using an alumina discharge tube, which has an inner diameter of 7.4mm, a tube thickness of 0.7mm and a distance of 83mm between the electrodes, and is for a 360W high pressure sodium vapor discharge lamp, such further experiments are made that a projection conductor 9 is formed to extend from the elec-trode 6 as shown in FIG. 4, and the starting voltages are measured for various gaps "d" between the end tip of the projection con-ductor 9 and the inside surface "e" of the -tube wall 1. A molyb-denum rod of 0.7mm diameter is used as the projection conductor 9 and is fixed to a stem part of the tungsten coil of the electrode 6 by spot welding. FIG. 5 is a side view of a high pressure sodium vapor discharge lamp in accordance with the present invention, wherein the discharge tube 100 shown in FIG. 4 is sealed in an evacuated glass bulb 21. FIG. 6 shows results of the e~periments, .
~ . i , 3~)~6~
which, in comparison with the curves of FIG. 3, show a drastic improvement of the starting voltage by the provision of the projection conductor 9.
Similar experiments were made for the lamps of various wattages, and similar results were obtained. Especially for high power lamps of 700W and lOOOW, the starting voltages are remarkably lowered. This can be elucidated that, in such high power lamps, wherein the gap "d" between the end surface of the electrode and the inside surface "e" of the tube wall 1 is large and hence a providing of only a starting aid conductor 8 on the outside surface of the tube wall 1 does not remarkably lower the starting voltage, such providing of the projection conductor 9 extending towards the starting aid conductor 8 can effectively raise the potential gradient in the gap.
An example manufactured embodying the present invention is as follows:
tube input power................................. 360W -discharge tube 1: inner diameter................. 7.4mm thickness of tube............. 0.7mm inter-electrode distance...... 83mm material....... single crystal alumina electrodes 6 and 7: outer diameter of coil....... 3.6mm starting aid conductor 8: molybdenum wire of..... 0.8mm projection conductor 9: molybdenum wire of....... 0.7mm distance l'd".................................... 0.5mm .
: ~ :
, ~ , , ,, ~
~:~3(~
sealed gas: sodium ......................... 4.5mg mercury ........................ 20mg xenon gas ..................... 350 Torr The starting aid conductor ~ is connected to the electrode 7 through a bimetal switch 10 as shown in FIG. 7, which is made open by means of a high temperature o~ the dis-charge tube 1, in order to disconnect the s~arting aid conductor 8 from the opposite electrode 7 after ignition to prevent loss of sodium from the discharge tube due to unnecessary connection of the starting aid conductor 8 to the opposite electrode 7.
The circuit of the lamp of this example is shown in FIG. 7, wherein commercial A.C. current is fed through a single choke ballast 14 for conventional 400W mercury lamp into the high pressure sodium vapor discharge lamp 15 in accordance with the present invention, wherein,in the bulb 21 or in the stem 22, are provided a bimetal starter switch 12, a series resistor 11, a 3000 pF ceramic capacitor 13 and the bimetal switch 10. As -shown in FIG. 7, the capacitor 13 and a series connection of the resistor 11 and the switch 12 are connected in parallel across the terminals 4 and 5 of the discharge tube, so that the lamp 15 can be started by known producing of a kick voltage by the choke coil 14. The series resistor 11 is to limit the cut-off current of the blmetal starter switch 1~ to the value of 0.5A and also serves to make the bimetal starter switch 12 open by a joule heat thereof. The capacitor 13 is for control-ling to suppress a producing of an extraordinary high kick ,, . ., .~ ,, .
,- . , .. . ..
... .. , .. ,. . ~,., ~, .. .
' ~
6~
voltage and also to shape the kick voltage pulse to have a necessary pulse width. Namely, the capacitor 13 serves to protect the lamp apparatus from insulation breakdown damage and also assure certainty of starting. Tests show that the starting voltage for the 360W lamp of the abovementioned example is about 2KV, and on the other hand, average value of induced high voltages across the terminals of the discharge tube 100 is about 2.5KV, which is sufficiently higher than the starting voltage of the lamp, and therefore the lamps are started with a high lo certainty. Furthermore, on account of lowness of the induced high voltage in the lamp apparatus in comparison with the con-ventional high pressure sodium vapor discharge lamps, there have been no insulation breakdowns of ~allast and circuit during burning tests of the lamps.
Another example of 630W lamp is made by embodying the present invention and with similar details of the deslgn except the following changes:
the inner diameter of polycrystalline - alumina discharge tube ............. 9.7mm the inter-electrode distance ............ 130mm distance "d" ............................ 0.5mm The abovementioned 630W lamp example has such low starting voltage as almost equal to that of the abovementioned example of 360W lamp, while starting voItage of a 630W lamp having similar making but no projection conductor 9 has a starting voltage of 4.5KV, that is higher by about l.OKV than .
,. ~
~3(~6~L
that of the above~entioned 360T~ lamp. The abovementioned 630r,~
lamp can be certainly and stably started by utilizing conventional single choke ballast for 700W mercury lam?.
It has been confirmed that the shape of the projection conductor 9 need not necessarily be in a rod shape, but can be shaped in a ring or a disk. The importance of the projection conductor 9 is that the distance "d" between the inner surface "e" of the tube wall 1 and the outer end of the projection conductor 9 is in a range of certain short distance. The dis-tance "d" should be from 0.3mm to 0.7mm. When the distance "d"is longer than 0.7mm, the lowering of starting voltage is not satisfactory. On thè other hand, when the distance "d" is shorter than 0.3mm, due to smallness of the gap7every igniting discharges always concentrates in a very small area, and hence the very small area is likely to receive an undesirable elfect, thereby inducing a high possibility of making cracks of the tube envelope. Tests show that the optimun distance is between o.4mm ~o 0.6mm.
....
-~., . . , ., -
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A high pressure sodium vapor discharge lamp comprising an outer bulb enclosing a discharge tube in an evacuated space therein, said discharge tube comprising a translucent and chemically stable tube envelope of alumina containing therein sodium, xenon gas, a buffer gas which is at least one member selected from the group consisting of mercury and cadmium and discharge electrodes sealed in both end parts of said tube enve-lope, characterized in that at least one of said discharge electrodes has a projec-tion conductor which is disposed extending therefrom towards and in proximity to an inside surface of a side wall of said tube envelope with a predetermined gap inbetween and that a starting aid conductor is disposed lengthwise on the outside surface of said side wall in a manner to face the outer end part of said projection conductor via said side wall, said starting aid con-ductor having a connection which impresses a potential substan-tially identical to that of the other discharge electrode.
2. A high pressure sodium vapor discharge lamp in accordance with claim 1, wherein said xenon gas is sealed to have a pressure of 150 Torr or more.
3. A high pressure sodium vapor discharge lamp in accordance with claim 1 or 2, wherein said predetermined gap between the outer end of said projection conductor and the inside surface of said side wall is between 0.3mm and 0.7mm.
4. A high pressure sodium vapor discharge lamp in accordance with claim 1 or 2 wherein said connection contains a switch which opens after starting of discharge of said discharge tube.
5. A high pressure sodium vapor discharge lamp in accordance with claim 4, wherein said switch is a bimetal switch which opens when exposed to a heat of said discharge tube.
6. A high pressure sodium vapor discharge lamp in accordance with claim 1 or 2, wherein said discharge lamp further comprises a capacitor and a series connection a starting switch and a current adjusting resistor connected in series each other, both said capacitor and said series connection are connected in parallel across both of said discharge electrodes.
7. A high pressure sodium vapor discharge lamp in accordance with claim 1 or 2, wherein said projection conductor and said starting aid conductor are molybdenum wires.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA337,048A CA1130361A (en) | 1979-10-04 | 1979-10-04 | High pressure sodium vapor discharge lamp with outside starting aid conductor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA337,048A CA1130361A (en) | 1979-10-04 | 1979-10-04 | High pressure sodium vapor discharge lamp with outside starting aid conductor |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1130361A true CA1130361A (en) | 1982-08-24 |
Family
ID=4115287
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA337,048A Expired CA1130361A (en) | 1979-10-04 | 1979-10-04 | High pressure sodium vapor discharge lamp with outside starting aid conductor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1130361A (en) |
-
1979
- 1979-10-04 CA CA337,048A patent/CA1130361A/en not_active Expired
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4322658A (en) | High intensity discharge lamp containing electronic starting aid | |
| US5955845A (en) | High pressure series arc discharge lamp construction with simplified starting aid | |
| US4135114A (en) | Starting device for discharge lamp | |
| US4316122A (en) | High pressure sodium vapor discharge lamp | |
| CN1151540C (en) | Metal halide lamp | |
| GB2032682A (en) | Arc lamp filling | |
| EP0060665B1 (en) | High pressure metal vapor discharge lamp | |
| EP0115653B1 (en) | Discharge lamp | |
| EP0089582B1 (en) | Intimate contact starting aid for arc lamps | |
| US3828214A (en) | Plasma enshrouded electric discharge device | |
| JP2003517710A (en) | High pressure discharge lamp | |
| CA1130361A (en) | High pressure sodium vapor discharge lamp with outside starting aid conductor | |
| US7423379B2 (en) | High-pressure gas discharge lamp having tubular electrodes | |
| Zaslavsky et al. | Improved starting of the 100-W metal halide lamp | |
| US4742275A (en) | High pressure metal vapor discharge lamp with starting element | |
| GB2060244A (en) | High Pressure Sodium Vapour Lamp | |
| JPH05325891A (en) | High pressure discharge lamp | |
| US5218269A (en) | Negative glow discharge lamp having wire anode | |
| US4521716A (en) | High-pressure metal vapor discharge lamp | |
| US4839560A (en) | Heatable electrode for high-pressure gas discharge lamps | |
| US4498030A (en) | High-pressure sodium vapor discharge lamp with bimetallic element | |
| JP2006100274A (en) | Lighting aid for high intensity discharge lamps | |
| JPS6364031B2 (en) | ||
| JPH0294352A (en) | High pressure sodium lamp | |
| KR840002223B1 (en) | High tension discharge lamp |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |