FR2489039A1 - DISCHARGE LAMP IN HIGH PRESSURE SODIUM STEAM - Google Patents

Abstract

THE INVENTION RELATES TO A LAMP FOR DISCHARGE IN HIGH PRESSURE SODIUM VAPOR 1 EQUIPPED WITH A DISCHARGE ENCLOSURE 3 PRESENTING A CERAMIC WALL AND CONTAINING XENON WHICH, DURING THE OPERATION OF THE LAMP, PRESENTS A PRESSURE OF AT LEAST 50KPA . THE POWER DISSIPATED DURING THE OPERATION OF THE LAMP IS A MAXIMUM 200 W. ACCORDING TO THE INVENTION, THE WALL OF THE DISCHARGE ENCLOSURE 3 HAS A THICKNESS, THE VALUE OF WHICH IS LESS THAN 0.5 MM AND AT LEAST EQUAL. At 0.2 MM. A LAMP IS OBTAINED WITH A SPECIFIC INCREASED LUMINOUS FLOW.

Description

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  "High-pressure sodium vapor discharge lamp

  The invention relates to a discharge lamp in high-pressure sodium vapor dissipating, in regime, a power of at most 200 W, provided with an enclosure having a ceramic wall, in which electrodes are arranged between which is the discharge during operation of the lamp, enclosure containing sodium, mercury and xenon, xenon having a pressure regime of at least

50 kPa.

  Such a lamp, which is of frequent use today-

  is known from the French patent application NO

  7 810 778. These lamps make it possible to achieve a luminous flux

  high specificity. Xenon serves as a buffer gas

  next to the mercury. Buffer gases limit losses

  conduction occurring in the discharge chamber

  the operation of the lamp. In the lamps

  a fairly high xenon pressure, the losses of

  are significantly lower than those produced by

  in lamps containing only mercury as gas

  buffer. It has been found that, during operation, the

  The highest temperature of the wall of the chamber of the known lamp is lower than that of a comparable lamp containing only mercury as a buffer gas. This results in a

  limitation of the specific luminous flux obtainable. This is happening

  in particular to lamps of reduced power, in particular

  with a power of less than 200 W. The aim of the invention is to indicate

  a method to avoid, at least partially

this disadvantage.

  According to the invention, a discharge lamp in

  high pressure sodium vapor of the kind mentioned above

  above is characterized in that the wall of the enclosure has a thickness, the value of which is less than

  0.5 mm and equal to at least 0.2 mm.

  In a high-pressure sodium vapor discharge lamp according to the invention, the specific luminous flux 24q9039 is increased with respect to the known lamp, of which

  a wall thickness of 0.6 mm is a common dimension

  rante. It is admitted that this is due, among other things, to the temperature

  increased ture of the relatively thin wall of the enclosure.

  Such an increase in temperature results in a more uniform variation of the radial temperature profile of the enclosure fill. It has been found that such a profile

  temperature is favorable for obtaining a lu-

  higher specific thinning. We get the advantage that,

  in thicknesses selected from the range indicated, the

  King of the enclosure is sufficiently resistant to the attack of the

  pleating of the enclosure, which was not to be expected.

  If the wall thickness is chosen less than 0.2 mm,

  the unavoidable impurities of the wall material and the

  network faults in the wall can create such weak areas in the wall of the enclosure that the latter is not gastight, or even breaks. During the life of the lamp, a non gas-tight enclosure leads to

  disappearance of the filling components of the enclosure.

  During the operation of the lamp, this results in a sharp increase in the arc voltage and a variation of the point

  color of the radiation emitted by the lamp.

  By "ceramic wall" it is necessary to hear a wall

  polycrystalline material, for example alumina

  dense sintered nium, or monocrystalline material, for example

full of sapphire.

  It should be noted that an improved temperature profile

  could be achieved by reducing the inter-

  do not of the enclosure. However, lamps of

  below 200 W have the disadvantage that, when operating on an AC voltage source, the necessary re-priming peaks increase as a result of the significant cooling of the discharge during the zero crossing of the current. In addition, the total output of the lamp

is affected.

  Preferably, the wall of the enclosure of a high-pressure sodium vapor discharge lamp according to the invention consists of polycrystalline material,

  at least 80% of the crystals have a large

  maximum of 60 μm. This has the advantage that, on the one hand, the wall is gas-tight without affecting, on the other hand, the light transmission through the wall as a result

  crystal boundaries and network faults.

  An embodiment of a lamp according to the invention

  will be explained in detail below with the aid of a

  sin given by way of non-limiting example.

  In the drawing, reference numeral 1 designates a

  outer bulb of the lamp with one side of a socket 2.

  In the outer bulb is arranged a discharge chamber

  3. The discharge vessel 3 contains sodium, mercury, xenon in an amount such that, during operation

  of the lamp, the xenon pressure is greater than 50 kPa.

  The discharge vessel 3 is provided with two electrodes 4 and 5

  between which the discharge takes place, during the

  of the lamp. The electrode 4 is connected to a rigid current input 7 by means of a metal strip 6. This current input 7 is connected to a connection member of the

  2. In turn, the electrode 5 is connected, by the

  metal strip 8, at a neck entrance,

  9, which is linked to another

xion of the base 2.

  The numeral 10 designates a glow choke, which is provided with a glass envelope 10a. In the glare choke are applied two bimetallic blades 11, 12, one of which is connected to the rigid current input 7, the other to the rigid current input 9. The discharge chamber of the lamp described consists of dense sintered aluminum oxide, of which at least 80% of the crystals have a large dimension

  up to 60 μm. The wall thickness is 0.45 mm.

  For the production of the discharge vessel, a mixture of aluminum oxide powder containing, by weight, 0.1 to 0.2% MgO was obtained. The mixture is compressed, with a binder (for example methylcellulose) and water, to obtain a plastic mass and then shaped

  in the form required by extrusion. Then, the pulverulent mixture

  The extruded prover is subjected to a two-phase sintering process, as described in German Pat. No. 2,313,760. In the first phase, the extruded tubular form is

  heated in air for 1 to 3 hours at a temperature of

  between 11000C and 14000C. In the second phase, the chau. fage is carried out at 18000C at 19000C during

  2 to 6 hours with passage of hydrogen.

  In operation, the lamp described absorbs a power of 70 W and is connected to an alternating voltage source of 220 V, 50 Hz, via an inductive stabilization ballast of about 0.6 H.

  Below, column 1 of the table mentions the

  the most important ranges of the lamp described and the

  lonne 2 those of a second lamp according to the invention. As regards the structure, the lamp according to column 2 is identical to that in column 1, but

  another operating pressure of xenon. For information

  parative, columns 3 and 4 mention the parameters of

  two lamps according to the state of the art, the loudspeaker

  load having a greater wall thickness and consisting of coarse grain material. For the rest, the structure of the lamps according to columns 3 and 4 is identical

  to that of the lamps according to the invention.

(See table on page 5).

248 q03S9

BOARD

  coform lamps with: lanpes according to the state) the invention: of the technique

1 2 3 4__

  to ---- to __ o _ _ _ _ _ _ _ _) (Power source (V, Hz): 220.50 (Power of lanpe (W): 70 (Spacenate electrodes (mm): 31 (Diameter Internal: 3.8 (Discharge Chamber (mm): (Wall Thickness (mm): 0.45 (Xen Pressn in the state of: 320 (Operation (kPa): (Mercury Weight Ratio: 5, 7 (re / sodium (Max. Temperature of: 1460 (wall (K)) (Specific luminous flux: (lm / W): (after 100 hours of: 102 (operation (after 2000 hours of: 97 (operation ( after 3000 hours of: 95 (operation (Creation of the voltage (arc after 20000 hours: - 1 (operating res (

: 220.50:

: 70:: 31:

: 3.8:

: 0.45:

: 709:

: 5.7:

::

1430:

: 110: o,

: 107: 95

: 110: 92

: -4

220.50)

: 70): 31)

8: 3.8)

:) 6: o0,6)

: 709)

:)

7: 5,7)

:)

: 1380)

:) :) :)

: 105)

:)

: 100)

  :): 97) :) :): -6) :) :) (Column (:

(

  From the table it appears that in the case of

  according to the invention, the specific luminous flux

  This is about 5% higher than that of lamps not in accordance with the invention. This gain in luminous flux

  specific can be maintained during the lifetime.

  In another example of a mpe according to the invention, the discharge vessel has a wall with a thickness of 0.3 mm. The xenon pressure occurring during operation of the lamp is about 1.06.103 kPa, and the maximum wall temperature is about 1560 K. The lamp dissipates a

  power of 70 W and after 100 hours of operation

  Specific luminous flux is 113 lm / W0. After 2000 hours of operation, the luminous flux

specific is 112 lm / W.

  The wall of the ampoule is constituted by dense sintered aluminum oxide, at least% of the crystals have a large dimension of

maximum 60 / um.

  After 2000 hours of operation, the

  arc voltage is increased by 3 V, while

  the color point of the radiation emitted during the 2000 hours of operation have the following values: - 0 hours of operation x = 0.544; y = 0.425 - 100 hours of operation x = 0, 544; y = o, 425 - 1000 hours of operation x = 0.541; y = 0.423

  - 2000 hours of operation x = 0.541; y = 0.424.

  It emerges that, during 2000 hours of operation, the filling of the discharge chamber remains practically constant with regard to the

quantity and composition.

Claims (2)

  1.- Discharge lamp in high pressure sodium vapor dissipating, in regime, a power of maximum   W, provided with an enclosure (3) having a ceramic wall   in which electrodes (4,5) are arranged between which the discharge occurs during the operation of the lamp, enclosure (3) which contains sodium,   mercury and xenon, xenon having a steady   at least 50 kPa, characterized in that the wall of the enclosure (3) has a thickness, the value of which is   less than 0,5 mm and equal to at least 0,2 mm.   2. Lamp according to claim 1, characterized in that the wall of the discharge vessel (3) is constituted   polycrystalline material, of which at least 80% of the   Rates have a large dimension of up to 60 ym.