US3548240A - Low-pressure sodium vapour discharge lamp - Google Patents

Low-pressure sodium vapour discharge lamp Download PDF

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Publication number
US3548240A
US3548240A US739830A US3548240DA US3548240A US 3548240 A US3548240 A US 3548240A US 739830 A US739830 A US 739830A US 3548240D A US3548240D A US 3548240DA US 3548240 A US3548240 A US 3548240A
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United States
Prior art keywords
lamp
sodium
discharge
protuberance
discharge tube
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Expired - Lifetime
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US739830A
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English (en)
Inventor
Raymond Francois Spiessens
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US Philips Corp
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US Philips Corp
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/24—Means for obtaining or maintaining the desired pressure within the vessel
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/70—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr
    • H01J61/74—Lamps with low-pressure unconstricted discharge having a cold pressure < 400 Torr having a main light-emitting filling of difficult vaporisable metal vapour, e.g. sodium

Definitions

  • This invention relates to a low-pressure sodium vapour discharge lamp comprising a discharge tube and an outer bulb surrounding it, wherein the space between the discharge tube and the outer bulb is substantially exhausted and wherein an amount of sodium which is not in vapour form in the operating condition of the lamp is present in a protuberance of the discharge tube, which protuberance is heated only by the heat evolved in the discharge tube.
  • substantially exhausted is to be understood to mean a pressure which i lower than approximately torr.
  • the discharge tube In a known lamp of the kind above referred to, the discharge tube.
  • the elevations form, as it were, containform of small shallow elevations which serve to prevent the sodium from being distributed unevenly over the discharge tube.
  • the elevations form, as it were, containers which ensure that sodium drops cannot be displaced or hardly. (This is the so-called blocking function.)
  • the temperature prevailing in the elevation is a little lower than that in the other portions of the discharge tube.
  • the blocking function for the sodium is even enhanced by this slightly lower temperature, since in practice sodium will not now be evaporated from an elevation and not bedeposited at another area, because this other area is hotter than the elevation.
  • An object of the invention is to arrive at a sodium lamp of the kind mentioned in the preamble in which the number of protuberances is small and nevertheless burning dark is avoided.
  • a low-pressure sodium vapour discharge lamp comprising a discharge tube and an outer bulb surrounding it, wherein the space between the discharge tube and the outer bulb is substantially exhausted and wherein in the operating position of the lamp an amount of sodium which is not in vapour form is present in a protuberance of the discharge tube, which protuberance is heated only by the heat evolved in the discharge tube, is characterized in that the protuberance lies entirely outside the discharge space and that in the operating position the protuberance contains substantially the full amount of sodium which is not in vapour form, the following condition being fulfilled:
  • V is the volume (in ccm.) of the protuberance and wherein A is the surface area (in sq. cm.) of the orifice between the protuberance and the discharge space.
  • discharge space is to be understood herein to mean that portion of the discharge tube in which the discharge occurs during the operation of the lamp.
  • a surprising advantage of a lamp according to the invention is that burning dark does not occur, even if the above-mentioned elevations are absent.
  • the (large) protuberance of a sodium lamp according to the invention will be referred to as appendix.
  • a lamp according to the invention can be heavily loaded, that is to say it can absorb a high power. Consequently the amount of light per unit volume of the discharge tube (expressed, for example, in lumens per litre) can be considerable.
  • a lamp has a larger or smaller number of lumens per litre, dependent upon the electric power absorbed and the output.
  • the number of lumens per litre of a lamp which is adjusted so as to have its maximum number of lumens/ watts is referred to as the G-value of this lamp.
  • this G-value is higher than in a corresponding lamp which is not provided with an appendix.
  • a corresponding lamp is to be understood to mean a lamp having the same dimensions, a similar thermal insulation and a similar igniting gas.
  • the appendix is preferably so formed that the condition V 2 AVA is fulfilled.
  • the protuberance is preferably located in the vicinity of an electrode of the discharge tube, since the efiiciency of the lamp, which is expressed, for example, in lumens per watt (the so-called specific light flux), is then higher than in the case of a different location of the appendix. If an appendix lies in the vicinity of the electrode the efficiency may, in practice, be equal to that of an otherwise corresponding lamp which is not provided with an appendix.
  • a sodium lamp according to the invention may be used, for example, for road lighting. If for this purpose use is made of lamps and fittings of the same size as before, the greater amount of light emitted by the new lamp permits of obtaining better road lighting, while the specific light flux when using a particular protruberance in the vicinity of an electrode may thus be substantially equal to that of a sodium lamp without the particular protuberance.
  • the orifice may be present, for example, at the level of this electrode.
  • the portion of the protuberance which is most remote from the orifice lies nearest to the electrode.
  • the protuberance may have various shapes, for example, the shape of a spiralised cavity.
  • the protuberance preferably has the shape of a cylinder the axis of which extends approximately in parallel with the axis of the adjacent portion of the discharge space.
  • the protuberance then has the advantage of a simple shape, which is thus inexpensive. Due to the particular location of the cylindrical protuberance as referred to above, it is achieved that the cross-section of the discharge tube, inclusive of the appendix, can be small.
  • the protuberance may be provided near a portion of one limb of the tube which is far remote from the other limb of the tube.
  • the protuberance is preferably intersected by a plane of symmetry of this tube, which is at right angles to the plane which passes through the axes of the limbs of the discharge tube.
  • This embodiment affords the advantage that the appendix, together with the two limbs of the discharge vessel, can provide a great space factor of the cross-section of the outer bulb.
  • the term space factor is to be understood herein to mean the ratio between the sum of the cross-sections of the two limbs of the discharge space and the cross-section of the appendix on the one hand and the internal cross-section of the outer bulb on the other hand.
  • the space factor can thus be great and hence the cross-section of the outer bulb can be small.
  • the outer bulb can therefore be cheap and provide better thermal insulation.
  • the discharge space may have the shape of, for example, a circular cylinder with the protuberance located externally of the circular profile.
  • the protuberance can be so arranged as to find itself, at least partly, in a re-entrant part of the wall of the discharge space.
  • This preferred embodiment affords the advantage that the cross-section of the discharge space at the appendix, and inclusive the cross-section of the appendix, can be small. This total cross-section need not even be larger, or not much larger, than that of other portions of the discharge space. In this space the cross-section of the outer bulb can be small, and, if desired, substantially uniform throughout. This preferred embodiment is important, especially for linear lamps in which little space is usually available between the discharge tube and the outer bulb.
  • the protuberance has, for example, an axis which is substantially rectilinear so that the lamp can satisfactorily operate in one position or in a few positions.
  • the low-pressure sodium vapour discharge lamp is given a protuberance which is worm-shaped, the axis of the protuberance, starting from the orifice, comprising successively the following portions:
  • a portion a which turns away from an electrode and also turns away from a plane P which passes through the axis of the adjacent portion of the discharge space and the centre of the orifice;
  • An advantage of this solution is that, at any position of the lamp, an appendix portion lies lower than the orifice, so that sodium is prevented from flowing out of the appendix at any position of the lamp.
  • volume of the appendix will naturally have to be so much larger than the volume of the sodium that the sodium which is not in vapour-form cannot reach the orifice at any operating position.
  • the protuberance comprises a container and a supply tube from the orifice to the container, at least part of the supply tube extending into the container.
  • This embodiment too, affords the advantage that the lamp can operate at several positions.
  • each ccm. volume of the discharge tube required, for example, approximately 2 milligrams of sodium, of which only a fraction was used for the discharge.
  • the sodium may be introduced into the discharge tube in several ways, for example, through an exhaust tube.
  • a low-pressure sodium vapour discharge lamp is preferably manufactured by a working method which utilises a capsule for introducing the sodium, which capsule contains the total amount of sodium required for the lamp and is sealed to the wall of the discharge space, establishing a free communication between the capsule and the discharge space in such manner that the capsule constitutes the protuberance of the discharge tube, whereafter the capsule is heated.
  • This working method affords the advantage that the desired dose of sodium can be introduced into the lamp in a simple manner, since the possibility of drops of sodium remaining in a container or a supply duct, for example, an exhaust tube (to be severed afterwards) is now eliminated.
  • the sodium will preferably be protected by a suitable gas which has previously been led into the capsule.
  • Heating the capsule is desirable, in order to bring traces of sodium via the orifice of the proturberance immediately into the discharge space.
  • the lamp can rapidly assume its operating condition even when it is lit for the first time, since it is not necessary to wait for sodium which leaves the capsule due to the heat of the discharge of an igniting gas in the lamp.
  • FIG. 1 is a perspective view of a sodium lamp according to the invention
  • FIG. 2 is a cross-sectional view of the lamp, taken on the line II-]1 of FIG. 1;
  • FIG. 3 is a cross-sectional view of the lamp taken on the line IIIIII of FIG. 2;
  • FIG. 4 is a perspective view of part of a discharge tube of a lamp according to the invention provided with a worm-shaped appendix,
  • FIG. 5 is a perspective vieW, in part section, of a part of a discharge tube of a lamp according to the invention provided with an appendix With supply tube;
  • FIG. 6 is a longitudinal section of part of a linear sodium lamp according to the invention.
  • the reference numerals 1 and 2 indicate the lamp cap and the outer glass bulb, respectively, of a 220-watt low-presure sodium vapour discharge lamp.
  • a U-shaped discharge tube 3 having limbs 4 and 5 respectively.
  • the portions of the limbs 4 and 5 which are adjacent the lamp cap 1 contain electrodes 6 and 7 respectively.
  • the limb 4 of discharge tube 3 is provided with a protuberance 8 which ends into the rectilinear portion of the limb 4 via an orifice 9 (see also FIG. 3).
  • a portion 10 of protuberance 8 which is remote from the orifice 9 is located in the vicinity of the electrodes 6 and 7.
  • the portion 10, which is adjacent the said electrodes contains an amount of sodium 11 which is fluid in the operating condition of the lamp.
  • FIG. 2 is a cross-sectional view, taken on the line IIII of FIG. 1, as viewed in the direction indicated by the arrow of FIG. 1.
  • FIG. 2 shows more details about the location of the proturberance 8 relative to the limbs 4 and 5 of the discharge tube. Corresponding elements of FIGS. 1 and 2 are provided with the same reference numerals.
  • the space between the limbs 4, 5 and the appendix 8, on the one hand, and the outer bulb 2 on the other is substantially exhausted.
  • the appendix '8 (see FIG. 2) is intersected by the plane of symmetry of the discharge tube, which passes through line 12 and is at right angles to the plane passing through the axes of the limbs 4 and 5.
  • FIG. 3 is a cross-sectional view of the lamp of FIG. 1 at the area where the proturberance 8 ends into the rectilinear portion of the limb 4 of the discharge tube. Corresponding elements of FIGS. 1, 2 and 3 are provided with the same reference numerals.
  • the lamp described with reference to FIGS. 1 to 3 has the data specified in the second column of the accompanying Table 1. Corresponding data for a lamp which is not provided with an appendix are given in the third column of Table I.
  • FIG. 4 shows an example of an appendix for a lamp which may be able to operate at various positions.
  • FIG. 4 shows a portion 20 of a discharge tube of a lamp according to the invention having a lamp cap 21, an electrode 22 within the portion 20, and a wormshaped appendix 23.
  • the orifice of appendix 23 in the discharge space is indicated by 24.
  • FIG. 4 also shows a reference plane P, which is a flat plane passing through the axis 25 of discharge tube 20 and through the center of orifice 24.
  • portion a which turns away from electrode 22 and also turns away from the plane P (portion a lies beneath the plane P);
  • FIG. 5 shows a portion 30 of a discharge tube of a lamp according to the invention having an appendix 31 shown in longitudinal section.
  • the appendix comprises a container 32, which contains sodium 34, and a supply tube 33, part of which extends into container 32.
  • the example of FIG. 5, too, is suitable for lamps which have to operate at several positions. If, for example, tube 30 is rotated in such manner that the appendix 31 with its container 32 becomes upright, then the sodium will accumulate between the portion of the supply tube 33 which extends into container 32, and the wall of container 32.
  • FIG. 6 shows another embodiment of a lamp according to the invention.
  • 50 indicates one lamp cap of a sodium lamp having a rectilinear discharge tube 51, the outer bulb being indicated by 52.
  • the cross-section of discharge tube 51 is similar at a short distance from electrode 53 than at a distance far remote from electrode 53 (far from lamp cap 50).
  • the discharge space has, slightly beyond electrode 53, a re-entrant part or dent which accommodates part of an appendix 54.
  • the orifice of the appendix in the discharge space is indicated by 55.
  • the diameter of the outer bulb 52 can yet be comparatively small.
  • the discharge space may, if desired, have further dents which do not accommodate appendices. It is also conceivable that a discharge space of a lamp according to the invention has a non-circular cross-section throughout or substantially throughout.
  • a low-pressure sodium vapour discharge lamp comprising a discharge tube and an outer bulb surrounding it, wherein the space between the discharge tube and the outer bulb is substantially exhausted and wherein an amount of sodium which is not in vapour form in the operating condition of the lamp is present in a proturberance of the discharge tube, said protuberance lying completely within the outer bulb and is heated only by the heat evolved in the discharge tube, said protuberance being entirely outside the discharge space and in the operating position containing substantially the full amount of sodium which is not in vapour form, the following condition being fulfilled:
  • V is the volume (in ccm.) of the protuberance and wherein A is the surface area (in sq. cm.) of the orifice between the protuberance and the discharge space.
  • a low-pressure sodium vapour discharge lamp as claimed in claim 1 in which the protuberance is wormshaped, and in order to be able to operate the lamp at various positions, the axis of the protuberance, starting from the orifice, comprises successively the following portions:
  • portion a which turns away from an electrode and also turns away from a plane P which passes through the axis of the adjacent portion of the discharge space and the center of the orifice;
  • a method of manufacturing a low-pressure sodium vapour discharge lamp comprising a discharge tube having a protuberance containing a supply of sodium which is not in vapour form during operation of the lamp, and an outer envelope surrounding the discharge tube and the protuberance comprising the steps of sealing a capsule containing the total amount of sodium required to the Wall of the discharge tube, establishing a free communication between the capsule and the discharge space in such mannet that the capsule constitutes the protuberance of the discharge tube, and thereafter heating the capsule to release the sodium.

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US739830A 1967-07-10 1968-06-25 Low-pressure sodium vapour discharge lamp Expired - Lifetime US3548240A (en)

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NL6709573A NL6709573A (enrdf_load_html_response) 1967-07-10 1967-07-10

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US (1) US3548240A (enrdf_load_html_response)
AT (1) AT280419B (enrdf_load_html_response)
BE (1) BE717798A (enrdf_load_html_response)
CH (1) CH485319A (enrdf_load_html_response)
ES (1) ES355868A1 (enrdf_load_html_response)
FR (1) FR1572848A (enrdf_load_html_response)
GB (1) GB1199535A (enrdf_load_html_response)
NL (1) NL6709573A (enrdf_load_html_response)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3784863A (en) * 1973-01-11 1974-01-08 Thorn Electrical Ind Ltd Vapour discharge lamps
US4393325A (en) * 1979-08-15 1983-07-12 U.S. Philips Corporation Low-pressure mercury vapor discharge lamp with mercury amalgam
GB2203283A (en) * 1987-01-29 1988-10-12 Toshiba Kk Lamp for generating ultraviolet radiation
WO2016135008A1 (en) * 2015-02-26 2016-09-01 Philips Lighting Holding B.V. Lighting device with dispenser for a reactive substance

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB473583A (en) * 1936-12-05 1937-10-15 Rnc Pavel Meisel Improvements in and relating to metal vapour discharge tubes
US2103039A (en) * 1929-07-10 1937-12-21 Gen Electric Gaseous electric discharge device
US3331977A (en) * 1965-03-15 1967-07-18 Westinghouse Electric Corp High output discharge lamp with vapor pressure control means

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2103039A (en) * 1929-07-10 1937-12-21 Gen Electric Gaseous electric discharge device
GB473583A (en) * 1936-12-05 1937-10-15 Rnc Pavel Meisel Improvements in and relating to metal vapour discharge tubes
US3331977A (en) * 1965-03-15 1967-07-18 Westinghouse Electric Corp High output discharge lamp with vapor pressure control means

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3784863A (en) * 1973-01-11 1974-01-08 Thorn Electrical Ind Ltd Vapour discharge lamps
US4393325A (en) * 1979-08-15 1983-07-12 U.S. Philips Corporation Low-pressure mercury vapor discharge lamp with mercury amalgam
GB2203283A (en) * 1987-01-29 1988-10-12 Toshiba Kk Lamp for generating ultraviolet radiation
US4835442A (en) * 1987-01-29 1989-05-30 Kabushiki Kaisha Toshiba Lamp for generating ultraviolet radiation
GB2203283B (en) * 1987-01-29 1991-01-02 Toshiba Kk Lamp for generating ultraviolet radiation
WO2016135008A1 (en) * 2015-02-26 2016-09-01 Philips Lighting Holding B.V. Lighting device with dispenser for a reactive substance
US10663116B2 (en) 2015-02-26 2020-05-26 Signify Holding B.V. Lighting device with dispenser for a reactive substance

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FR1572848A (enrdf_load_html_response) 1969-06-27
AT280419B (de) 1970-04-10
DE1764615A1 (de) 1971-09-09
NL6709573A (enrdf_load_html_response) 1969-01-14
DE1764615B2 (de) 1976-07-29
BE717798A (enrdf_load_html_response) 1969-01-08
CH485319A (de) 1970-01-31
GB1199535A (en) 1970-07-22
ES355868A1 (es) 1970-03-16

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