DE2201831A1 - Arc discharge device - Google Patents

Description

DiPL.-iNG. KLAUS NEUBECKER

Patent attorney
4 Düsseldorf 1 ■ Schadowplatz 9

Düsseldorf, January 14, 1972 40,663
71169

Westinghouse Electric Corporation
Pittsburgh, Pa., V. St. A.

Arc discharge device

The present invention relates generally to arc discharge devices, in particular on so-called metal halide discharge devices, in which predetermined amounts of selected, the discharge-maintaining substances are used to the To improve the performance of the device.

The object of the present invention is to provide an arc discharge device with a filling that maintains the discharge, with which, in addition to an effective discharge, an optimal degree of efficiency can be achieved at a relatively low piston temperature.

To solve this problem, an arc discharge device with a tightly sealed, elongated light-permeable device is provided Piston of predetermined volume, leads tightly guided through the piston, which are electrically connected to within the piston in a certain Spaced electrodes are connected, a metal halide filling enclosed in the flask to maintain the discharge, the filling a small amount of inert ionizable ignition gas and a predetermined amount Contains mercury, characterized according to the invention, that the mercury is the only one with complete evaporation The discharge maintaining component is present in an amount

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which is able to generate a mercury vapor working pressure between 3 and 15 atmospheres based on an average mercury vapor temperature of 2000 ° K, and that the filling also contains at least one praseodymium, neodymium or cerium halide, with the exception of fluoride, in a total amount between 1.4 χ 10 ~6 and 5.4 10 ~5 mol / cm distance between the electrodes, furthermore cesium halide, with the exception of the fluoride _/ in an amount of 3.5 χ 10 ~7 to 5.4 χ 10 ~ 5 mol / cm distance between the electrodes and the molar ratio between praseodymium, neodymium and cerium halide on the one hand and cesium halide on the other hand is between 4: 1 to 1: 2.5.

The flask can contain at least one sodium, dysprosium or samarium halide, as a further, additional filling that maintains the charge. with the exception of the fluoride, the molar ratio of the dysprosium halide and the samarium halide to that at least one praseodymium, neodymium or cerium halide less than 5: 1 and the molar ratio of the sodium halide to the cesium halide is less than 5: 1.

In addition, the piston can be used as additional filling components Maintaining the discharge at least one holmium, scandium, Contain gadolinium or indium halide, with the exception of fluoride, wherein the molar ratio between the holmium, scandium or gadolinium halides to the at least one praseodymium, Neodymium or cerium halide less than 5: 1 and the molar ratio of the indium halide to the at least one praseodymium, neodymium or cerium halide is less than 1: 1.

The invention is described below with reference to exemplary embodiments in Connection explained with the accompanying drawing. In the drawing show:

Fig. 1, partially in section, a discharge lamp with a inner quartz bulb, which has a filling to maintain the discharge according to the present Invention includes;

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2 shows a somewhat modified embodiment of the discharge device, being only a partial sectional view of the inner discharge tube is shown, which is made of polycrystalline aluminum oxide or the like There is a heat-resistant piston material and a filling that is used to maintain the charge according to the present invention; and

Fig. 3 is a graph to illustrate the dependence of the relative efficiency on the Mininujt piston temperature, where the lower piston temperatures are reproduced to achieve the optimum efficiency when using a necessary to maintain the discharge serving charge according to the present invention are.

The discharge device or lamp 10 shown in detail with FIG. 1 has generally the same structure as the known ones High-pressure mercury vapor lamps with radiation-permeable sealed inner discharge tube 12, at the ends of which electrodes 14 are arranged to maintain a vapor discharge. Inside the discharge tube 12 there is a certain one Quantity 16 and a small quantity of inert ionizable ignition gas such as argon at a pressure of 20 torr. The crowd 16 Mercury is present in such an amount as is necessary to be the only one sustaining the discharge at full evaporation Component to provide a mercury vapor working pressure of 3 to 15 atmospheres, calculated on the basis of a average temperature for the evaporated mercury of 2000 ° K. This average temperature can vary depending on the use of the various charge-maintaining substances and the working conditions of the lamp the specified numerical value represents a representative average temperature for the evaporated mercury. Since the flask volume is always is known, can be used to ensure the desired work

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-A-

Easily calculate the amount of mercury required under working conditions. When the discharge device is in operation, the other substances used to maintain the discharge can also affect the mercury act to influence the actual working pressure of the mercury. Furthermore, the extreme temperature gradients between the actual discharge arc and the bulb wall have an influence on the actual inside the discharge device exert prevailing pressure. It is therefore more accurate to state the required amount of mercury than if this substance were used on its own the only constituent that sustains the discharge would be because the amounts of mercury placed in the discharge tube are known and the resulting pressure as determined by the aforementioned mercury vapor temperature is easily determined can be.

An amount 18 is introduced into the discharge tube 12 which contains at least one praseodymium, neodymium or cerium halide, with the exception of fluoride. The total amount is between 1.4 χ "** to 5.4 χ 10 -5 mol / cm distance between the electrodes 14. According to a special embodiment, the electrodes 14 can be spaced 7 cm apart, given the volume of the discharge tube 12 of 20 cm ^. In the discharge tube 12 there is also an amount of cesium halide, with the exception of fluoride, in an amount of 3.5 10 ⁷ to 5.4 χ 10 ⁵ mol / cm distance between the electrodes 14 According to the present invention, the molar ratio between the total amount of praseodymium, neodymium and cerium halide on the one hand and cesium halide on the other hand is between 4: 1 to 1: 2.5.

A tightly sealed one that is permeable or transmitting to radiation outer bulb 24 surrounds the discharge tube 12 at a certain distance therefrom, with the space thus formed between the discharge tube 12 and the outer bulb 24 is preferably evacuated. Electrical leads 26 are tight through both the inner discharge tube 12 as well as the outer bulb 24 are guided to the electrodes 14 electrically with a conventional To be able to connect energy source (not shown).

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The discharge tube 12 further includes an ignition electrode 30, the Via an ignition resistor 32 with one end of one of the electrical Leads 26 is connected. The discharge tube 12 is attached to the outer bulb 24 by means of a conventional support frame 34 in the Kept their distance. With the help of ribbon conductors 36, the hermetically sealed implementation of the supply lines 36 through the ends of the Discharge tube 12 facilitated. The supply lines 36 are sealed through the outer piston 24 with the aid of a constricted pinch foot 38 out and thereby connected to a conventional base 30, via which an electrical connection to a suitable one is easy Energy source can be produced. The lamp 10 shown in FIG. 1 can according to a special exemplary embodiment be designed for an input power of 500 W.

In a modified embodiment 42, as shown in FIG is shown, the discharge tube 44 has a high density sintered polycrystalline alumina body, on the Ends end caps 46 are tightly connected. In the vicinity of the ends of the discharge tube 44 are suction and filling tubes 50, the serve to support the electrodes 48 at the same time. In accordance with the present invention, the amount is 16 mercury, an amount 18 of at least praseodymium iodide, neodymium iodide or cerium iodide and an amount of 20 cesium iodide in a given Quantity - as explained in connection with the preceding embodiment - together with the small amount of inert ionizable ignition gas included. In the finished practical embodiment, the discharge tube 44 is again similar - As explained in connection with FIG. 1 - within an outer piston, the other details again being the usual ones Have execution, as also already described in connection with Fig. 1 for the sake of completeness.

As previously pointed out, the essential constituents of the charge retentive fill are the small amount of inert ionizable ignition gas, mercury in the amount required to create a working vapor pressure for mercury alone the size of 3-15 atmospheres is necessary, a given one

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Amount of at least one praseodymium, neodymium or cerium halide, with the exception of fluoride, a specified amount of cesium halide, with the exception of fluoride, in compliance with a special one relative molar ratio between these rare earth metal halides on the one hand and cesium halide on the other hand. The mercury has the task of ensuring a suitable voltage drop between the electrodes. In connection with the cesium halide the relatively high mercury vapor pressure and the cesium halide serve to reduce the minimum bulb temperature or the so-called "cold spot" fbold-spot) - temperature at which the lamp works with optimum efficiency. The specially specified rare earth metal halides are used to form an extremely effective discharge, preference being given to cerium halide. According to a special embodiment, at which the discharge tube encloses a volume of about 20 cm ^ and the electrodes are 7 cm apart, a trapped mercury amount of about 200 mg results in a mercury working pressure of about 8 atmospheres. In connection with the mercury filling, cerium triiodide is in an amount of 20 mg and Cesium iodide included in an amount of 10 mg. Instead of this triiodide in an amount of 20 mg or neodymium triiodide in an amount of 20 mg can be used to reduce the cerium iodide in the replace the previous example. These rare earth metal iodides can be mixed if desired.

To improve the color effect and color rendering behavior of fillings of the prescribed type used to maintain discharge, it is advantageous to use one or more of the to use the following halides, with the exception of fluorides, namely sodium halide, dysprosium halide and / or samarium halide. A sodium halide provides radiation in the yellow-orange range of the visible spectrum, dysprosium halide for one red and blue emission and samarium halide for a bluish white emission. The other supplementary rare earth metal halides can be viewed as partial substitutes for the praseodymium, neodymium and / or cerium halides, although these additional, supplementary halides always in a total amount of

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At least 1.4 χ ΙΟ " ⁶ mol / cm electrode spacing should be present. The sodium halide can be regarded as a partial replacement for the cesium halide, although the cesium halide is always present in an amount of at least 3.5 χ 10" ^ mol / cm electrode spacing should. Preferably, the supplementary side earth metal halides highlighted above, namely dysprosium halide and samarium halide, are present in approximately the same molar amount as the praseodymium, neodymium and / or cerium halides, the molar ratio of additional, supplementary rare earth metal halides to these required halides not exceeding 5; 1 should be. Preferably, the sodium halide is present in approximately the same molar amount as the cesium halide, the molar ratio of sodium halide to cesium halide not being greater than 5: 1.

Fig. 3 shows in the form of a diagram the dependence of the relative Efficiency from the minimum piston temperature for various embodiments according to the present invention manufactured discharge devices. Besides, this is

Ver
Equivalent behavior for the same devices is shown. The curve labeled A shows the luminous efficiency as a function of the minimum bulb temperature for a discharge tube doped with 20 mg cerium triiodide, 20 mg dysprosium triiodide, 0.4 thallium and 50 mg mercury, with mercury being the only substance that maintains a discharge at a mercury vapor working pressure of would give about 2 atmospheres. The discharge tube had an electrode spacing of 7 cm and a volume of 20 cm ³ . As can be seen, curve A is essentially straight. Since the maximum realizable bulb temperatures are limited for practical reasons, the efficiency that can be achieved by means of such a discharge device operating according to curve A is also limited.

In the curve labeled B, the thallium was replaced by 15 mg cesium iodide and thus - as illustrated by curve B. - at a mercury vapor working pressure of about 2 atmospheres, a maximum efficiency with a slightly reduced minimum

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ler piston temperature achieved. The optimum efficiency resulted at a minimum bulb temperature of about 910 ° C. However, such a temperature is for a practical lamp design still unacceptably high.

For the curve labeled C was the filling of a lamp bulb with an electrode spacing of 7 cm and a volume of 8 cm ^ with 10 mg cerium triiodide and 10 mg dysprosium triiodide, together with 150 mg mercury, spiked. That would give a working pressure of around 15 atmospheres for mercury alone. As can be seen the curve C is straight again.

In the curve marked D, the discharge tube, which had an electrode spacing of 7 cm and a volume of 8 cm ^, was doped with 10 mg cerium triiodide, 10 mg dysprosium triiodide, 10 mg cesium iodide and 100 mg mercury, which when used as the only substance for maintaining the discharge would have generated a working pressure of mercury vapor of approximately 10 atmospheres. An optimal efficiency of about 155 lumens / W was achieved at a minimum bulb temperature of about 665 ° C., a temperature that can easily be achieved with the aid of a quartz discharge tube. If the mercury pressure increases above the mercury pressure as prevails when one corresponding to curve D working lamp, the required minimum for optimum efficiency-bulb temperature is further reduced, as is indicated by the curve e. This curve E shows the behavior of a similar discharge tube which is doped with about 10 mg of cesium iodide, 10 mg of dysprosium iodide, 10 mg of cerium triiodide and 150 mg of mercury, with the amount of mercury as the only component that maintains a charge would result in a mercury vapor working pressure of about 15 atmospheres . With this embodiment, the optimum efficiency could be achieved at a minimum bulb temperature of about 520 ° C, a temperature that can be achieved with conventional lamp designs without difficulties. In conjunction with cesium iodide and a high proportion of mercury, cerium iodide is essential to achieve optimum efficiency at a relatively low minimum bulb temperature.

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For preference, like that with curves D and E of FIG. 3 is illustrated, however, the cerium iodide can be replaced by an equivalent molar amount of praseodymium iodide or neodymium iodide. This leads to a high, optimal degree of efficiency while reducing the minimum piston temperature.

As already stated, to achieve a useful minimum piston temperature the pressure of the mercury vapor can be so pronounced that when used alone as the discharge sustaining Filling the mercury vapor pressure in a discharge device would be between 3 and 15 atmospheres. For a discharge tube with a volume of approximately 20 cm * * like it previously described in connection with the preferred embodiment, the mercury doping or admixture is intended make up between 75 mg and 375 mg. Preferably the mercury vapor pressure should be lie between 4 atmospheres and 10 atmospheres during operation of the discharge device, including for the one described preferred embodiment a mercury dose between 100 mg and 250 mg is required. At a mercury vapor pressure of 4 atmospheres, the minimum piston temperature required to achieve optimum efficiency is proportionate low. If the mercury vapor pressure is above 10 atmospheres, the discharge arc tends to be unstable.

In summary it can be said that through the use of cesium halide in connection with the relatively intense mercury content and together with the praseodymium, neodymium and / or Cerium iodide for a relatively low bulb temperature an effective discharge is achieved and an optimal degree of efficiency is made possible. The relationships on which these processes are based could not be fully clarified, however, it appears that the increased mercury pressure in connection with the Cesium halide increases the proportion of the desired radiating substance in the arc and for a more diffuse discharge with a lower, closer to the optimal sheet temperature. The resulting wider discharge arc has a less tendency to flex during operation, and even

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if this is the case, the wider arc will only have a less damaging effect on the piston because it will have a lower one Temperature and is less concentrated.

If desired, additional, additional fillings can be used to maintain the discharge in order to further modify the discharge. Examples of such other halides, again with the exception of fluorides, of course, are holmium, scandium, gadolinium and indium halides. Holmium produces an additional red and blue radiation, scandium a strong blue and additional additional radiation, gadolinium an additional blue radiation, while indium provides an additional blue radiation. If these substances are used in addition, the molar ratio of the holmium, scandium and gadolinium halides in relation to the praseodymium, neodymium and / or cerium halides should be less than 5: 1 and the molar ratio of the indium halide to the rare earth metal halides less than about 1: Be 1. For practical reasons, each of these additives should be present in an amount of at least about 1.4 χ " ⁶ mol / cm distance between the discharge tube electrodes, although smaller amounts can also be used if necessary.

In the above exemplary embodiments, in particular the Iodides are taken into account, but it is understood that instead of this the bromides or the chlorides in equivalent molar proportions can be used. Instead of this, any mixture of iodide, bromide and / or chloride can also be used, if desired. The specific curves of FIG. 3 showing the performance behavior relate to a mixture of cesium iodide and Cerium iodide, to which dysproslum iodide is also added, however the other additional halide additives give similar results, albeit in terms of color of the discharge and color rendering properties this discharge is based on the respective additional aggregate and according to the amount in to which the aggregate is added. The additional substance proportions are preferably generally approximately the same Molar amounts such as the praseodymium, neodymium and / or cerium halides

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used, with only N * tö.umhalogenid as an additive insofar as a The exception is when it is used in approximately the same molar amount as the cesium halide, if possible.

A particularly interesting composition of fillers for maintaining the discharge is an association of Ceriumhalogenid, sodium halide, samarium as dihalide and cesium halide. According to a particular embodiment, a discharge tube with an electrode distance of 7 cm and a volume of 20 cm ³ with 200 mg of mercury, 8 mg cerium triiodide _f 5 mg sodium iodide, 15 mg samarium dibdld and 5 mg cesium iodide spiked. Argon at a pressure of 20 Torr is used as the ignition gas. A discharge tube according to this special embodiment works with an efficiency of 140 lumens / W when it is operated with a minimum bulb temperature of 560 ° C. The above-mentioned so-called doping results in a mercury vapor pressure of about 8 atmospheres, the Ceriumiodid and cesium iodide are to 3 χ in an amount of about 2 10 ^-6 mol / cm electrode gap, the samarium iodide and sodium iodide, however, in an amount of about 5 χ 10 ~ 6 mol / cm electrode gap present. The color of the discharge is essentially white and the color rendering of illuminated objects is good.

Claimsι 209832/0750

Claims (12)

Claim e: Arc discharge device with a tightly sealed, elongated, translucent bulb of predetermined volume, Leads passed through the piston and electrically connected to the inside of the piston at a certain distance mutually arranged electrodes are connected to a metal halide filling enclosed in the flask Maintaining the discharge, the filling a small amount of inert ionizable ignition gas and a predetermined amount Contains mercury, characterized in that the mercury is the only one responsible for the discharge in the event of complete evaporation sustaining component is present in an amount capable of maintaining a mercury vapor working pressure between To generate 3 and 15 atmospheres based on an average mercury vapor temperature of 2000 ° K, and that the filling also contains at least one praseodymium, neodymium or cerium halide, with the exception of fluoride a total amount between 1.4 10 and 5.4 χ 10 ~ mol / cm Distance between the electrodes, furthermore cesium halide, with the exception of the fluoride, in an amount of 3.5 χ 10 to 5.4 χ 10 mol / cm distance between the electrodes and the molar ratio between praseodymium, neodymium and cerium halide on the one hand and cesium halide on the other hand between 4: 1 to 1: 2.5. 2. Discharge device according to claim 1, characterized in that the mercury is present in an amount that is at full Evaporation is sufficient to produce a mercury vapor working pressure between 4 and 10 atmospheres. 3. Discharge device according to claim 1 or 2, characterized in that that the halides are iodides. 4. Discharge device according to claim 1, 2 or 3, characterized in that that the mercury in an amount of 5 - 209832/0750 12.5 mg / cm of the given volume of the flask present is. 5. Discharge device according to one or more of the claims 1 - 4, characterized in that the piston also as additional filler to maintain the discharge of at least one of the halides - with the exception of the fluoride of the Contains sodium, dysprosium or samarium, at a molar ratio of the dysprosium and samarium halide to that at least one praseodymium, neodymium and cerium halide less than 5: 1 and a molar ratio of the sodium halide to the cesium halide of less than 5: 1. 6. Discharge device according to claim 5, characterized in that the dysprosium halide and the samarium halide in one Amount of at least 1.4 χ 10 mol / cm electrode spacing and the sodium halide are present in an amount of at least 3.5 10 mol / cm electrode spacing. 7. Discharge device according to claim 5 or 6, characterized in that that the halides are iodides. 8. Discharge device according to claim 5, 6 or 7, characterized in that that the additional filling fraction to maintain the discharge of samarium dihalide and sodium halide is formed. 9. Discharge device according to claim 8, characterized in that the available mercury vapor pressure has a magnitude of 8 atmospheres, cerium as the triiodide in its own amount of about 2 to 3 χ 10 mol / cm electrode spacing, cesium as the iodide in an amount of 2 to 3 χ ΙΟ "" ⁶ mol / cm electrode spacing, samarium as the diiodide in the amount of about 5 χ ίο " ⁶ mol / cm electrode spacing and the Na- -6 trium as the iodide in the amount of about 5 10 mol / cm There is a gap between the electrodes. 209832/0750 10. Discharge device according to one or more of claims 5-9, characterized in that the piston further has an additional, additional filler to maintain the charge of at least one halide - with the exception of the Fluoride - containing holmium, scandium, gadolinium or indium, at a molar ratio of holmium, scandium and Gadolinium halides to the at least one praseodymium, neodymium or cerium halide of less than 5: 1 and a molar ratio of the indium halide to the at least one praseodymium, neodymium and cerium halide of less than 1: 1. 11. Discharge device according to claim 10, characterized in that that the scandium, holmium and gadolinium halide and the indium iodide in an amount of m;
Electrode gap are present. Indium iodide in an amount of at least 1.4 10 mol / cm 12. Discharge device according to claim 11, characterized in that that the halides are iodides. KN / hs / sg 3 209832/0750