JP2013511117A - Mercury-free high-pressure discharge lamp with a reduced proportion of zinc halide - Google Patents

Abstract

The invention comprises a filling for generating a gas discharge and an electrode (11, 12) configured as a mercury-free filling comprising at least xenon and halides of sodium, scandium and zinc. The invention relates to a high-pressure discharge lamp for a vehicle headlight comprising a hermetically closed discharge vessel (10) having a discharge space (106) in which is enclosed. The filling has zinc halide at a rate ranging from 0 mg to 1 mg per 1 cm ³ of the discharge space volume, and the amount of halide present in the discharge space (106) of the discharge vessel (10) is the discharge space. The xenon low-temperature filling pressure is in the range of 1.0 MPa to 1.8 MPa, and the volume of the discharge space (106) of the discharge vessel (10) is 0.015 cm per cm ³ of volume. ^It has a value in the range of ³ to 0.022 cm ³ .

Description

  The invention relates to a high-pressure discharge lamp as described in the superordinate concept of claim 1.

I. Prior art Such a high-pressure discharge lamp is disclosed, for example, in EP 1 351 276 A2. This publication discloses a high-pressure discharge lamp for vehicle headlights with a mercury-free filling in which the proportion of zinc iodide is in the range of 2 to 6 mg per cm ^{3 of} discharge vessel volume.

  Publication US 7,126,281 B1 has a vehicle head with a mercury-free filling, which has a power consumption of about 35 W and contains xenon and halides of sodium, scandium, indium and zinc as metals. A high pressure discharge lamp for a light is disclosed.

  The zinc component of the filling replaces the previously used mercury and is required for adjusting the so-called lamp voltage of high pressure discharge lamps. The concept of lamp voltage is the high-pressure discharge lamp after the ignition and start-up phases of the high-pressure discharge lamp have been completed and an almost stable operating state has been reached, in which all the filling components are present in the gaseous state. Represents the operating voltage. However, the use of a zinc component in the filling has the disadvantage that the luminous flux produced by the high-pressure discharge lamp decreases as the proportion of zinc in the filling increases.

II. DISCLOSURE OF THE INVENTION The object of the present invention is to provide a high-pressure discharge lamp as mentioned at the outset, which does not have the aforementioned drawbacks. In particular, the power consumption is reduced compared to the above-mentioned prior art, it has an equivalent lamp voltage, and generates a sufficiently high luminous flux for use as a light source in a vehicle headlight, which is mercury-free. A high-pressure discharge lamp with a filling should be provided.

  This object is achieved according to the invention by a high-pressure discharge lamp having the structure described in the characterizing part of claim 1. Particularly advantageous embodiments of the invention are described in the dependent claims.

The high-pressure discharge lamp according to the present invention is provided as a light source in a front headlight of a vehicle, and is hermetically closed with a discharge space in which an electrode and a filling for forming a gas discharge are enclosed. A discharge vessel. The filling is configured as a mercury-free filling containing at least sodium, scandium and zinc halides and xenon. According to the invention, the filling is a zinc-free filling in which the proportion of zinc is reduced or the proportion of zinc halide is in the range of 0 mg to 1.0 mg per cm ^{3 of} discharge space volume. The amount of halide in the discharge space is in the range of 8 mg to 15 mg per cm ^{3 of the} discharge space volume, and the xenon low-temperature filling pressure (ie xenon in the discharge space measured at a temperature of 25 ° C.). Pressure) is in the range of 1.0 MPa to 1.8 MPa, and the volume of the discharge space is in the range of 0.015 cm ³ to 0.022 cm ³ . The concept of mercury-free filling means that neither mercury nor mercury compounds are enclosed in the discharge space of the discharge vessel.

  According to the present invention, the above feature reduces power consumption as compared with a high-pressure discharge lamp according to the prior art at an equivalent lamp voltage, and generates a sufficiently high luminous flux. A high-pressure discharge lamp suitable for the light source is realized. In particular, a high luminous flux can be achieved by reducing the zinc and zinc halide in the filling. The relatively high filling pressure of xenon, together with the small volume of the discharge space and the doping of the metal halide, contributes to the sufficiently high lamp voltage of the high-pressure discharge lamp, so that the lamp voltage of the high-pressure discharge lamp according to the invention is adjusted. As a result, the addition of mercury or a mercury compound to the filling can be omitted.

Advantageously, in order to compensate for the sufficiently high lamp voltage and luminous flux of the high-pressure discharge lamp, the proportion of zinc halide in the filling is greater than 0 mg per cm ^{3 of} discharge space volume, and advantageously the discharge space volume. In the range of 0.1 mg to 1.0 mg per 1 cm ³ . FIG. 3 schematically shows the relationship between the ratio of zinc halide in the amount of halide in the discharge space (unit weight%), the luminous flux of the high-pressure discharge lamp (curve 1), and the lamp voltage of the high-pressure discharge lamp (curve 2). Has been shown. On the horizontal axis, the percentage of zinc halide associated with the total amount of halide in the packing is plotted in units of weight percent. On the vertical axis, the luminous flux of the high-pressure discharge lamp is plotted in lumens on the one hand (left side in FIG. 3) and the lamp voltage of the high-pressure discharge lamp is plotted in volts on the other hand (right side in FIG. 3). Yes. Curve 1 (solid line) shows the relationship between the luminous flux of the high-pressure discharge lamp and the zinc halide in the packing, whereas curve 2 (dashed line) shows the lamp voltage of the high-pressure discharge lamp and the zinc halide in the packing. Showing the relationship. From curves 1 and 2 it can be clearly seen that as the proportion of zinc halide increases, the lamp voltage of the high-pressure discharge lamp increases and the luminous flux decreases.

  Advantageously, the filling of the high-pressure discharge lamp according to the invention further contains indium halide, the proportion of indium halide in the filling being not more than 3.0% by weight of the total amount of halide, and therefore Much less than the proportion of sodium halide and scandium halide in the packing. A small proportion of the indium halide in the filling is used to adjust the chromaticity coordinates of white light emitted from the high pressure discharge lamp in a standard color system according to CIE 1931 and DIN 5033. By using a relatively small proportion of indium halide in the filling, it is ensured that the high-pressure discharge lamp according to the invention forms white light according to standard ECE regulation 99. When the proportion of indium halide is relatively large, the luminous flux of the high-pressure discharge lamp may be adversely affected.

  Advantageously, the proportion of sodium halide in the filling is from 30% by weight of the total halide content in order to form white light according to standard ECE regulation 99, having a color temperature in the range of 4000K to 4500K. The proportion of scandium halide in the packing is in the range of 30% to 60% by weight of the total amount of halide. In addition, the filling of the high-pressure discharge lamp according to the invention contains thulium, for example thulium in the form of thulium halide, for the purpose of adjusting the lamp voltage, the proportion of thulium halide being 10% by weight of the halide. To 30% by weight. The action of thulium here is similar to that of zinc, that is, the lamp voltage increases and the luminous flux decreases as the ratio of thulium increases, but it is not as great as that of zinc.

  Advantageously, the proportion of zinc halide in the packing is not more than 6% by weight with respect to the total amount of halide. Thus, a sufficiently high lamp voltage (40 V) can be generated without excessively reducing the luminous flux due to the addition of zinc.

The discharge vessel of the high-pressure discharge lamp according to the invention advantageously has an elliptical outer contour in the region of the discharge space, and has a cylindrical inner contour in the region between the electrodes, Regarding the ratio of the wall thickness of the discharge vessel, the following relationship 1.0 ≦ D1 / D2 ≦ 1.4
On the contrary, the following relation 1.2 ≦ D1 / D2 ≦ 1.3 is advantageous
Where D1 is the wall thickness of the discharge vessel in the region between the electrodes, and D2 is the wall thickness of the discharge vessel in the end section of the discharge space in which the electrodes are arranged.

  Based on the above wall thickness ratio, the discharge vessel of the high-pressure discharge lamp according to the present invention has a convex curved portion smaller than the discharge vessel of the high-pressure discharge lamp according to the prior art. Therefore, in the high-pressure discharge lamp according to the present invention, an actual electrode interval (measured by X-ray imaging) larger than the electrode interval in the high-pressure discharge lamp according to the prior art is used, for example, according to the ECE regulation 99, An optical spacing of 4.2 mm as indicated with respect to the playing card or optically acting can be achieved. For example, the actual electrode spacing in the high-pressure discharge lamp according to the prior art is 3.6 mm, whereas the actual electrode spacing in the high-pressure discharge lamp according to the invention is preferably in the range from 3.8 mm to 4.0 mm. . The relatively large electrode spacing likewise contributes to the relatively high lamp voltage of the high-pressure discharge lamp according to the invention, so that for this reason also the amount of zinc component is reduced and the packing A sufficiently high lamp voltage can be achieved even though mercury is omitted in FIG.

  Preferably, the discharge vessel is in the range between 2.0 mm and 2.7 mm in the area between the electrodes, particularly preferably in the range 2.1 mm to 2.4 mm and in the range 5.0 mm to 6.0 mm, particularly preferably. Has an outer diameter of 5.3 mm to 5.7 mm. Thereby, the discharge vessel has a relatively thick wall thickness in the region between the electrodes, and such a thick wall thickness contributes to improved protection against cracking and good thermal insulation of the discharge vessel.

  The electrodes of the high-pressure discharge lamp according to the invention are preferably configured in the form of rods in order to ensure a high current load capability of the electrodes, and are preferably in the range from 0.20 mm to 0.30, in particular Since it preferably has a diameter in the range from 0.25 mm to 0.27 mm, the high-pressure discharge lamp according to the invention starts immediately after the ignition phase and starts up in which the filling halide evaporates. It is possible to operate at a value of 3 to 5 times the rated power during the phase, so that the fastest possible transition to a nearly stable operating state of the high-pressure discharge lamp can be achieved.

  As already mentioned above, the low-temperature filling pressure of xenon in the filling of the high-pressure discharge lamp according to the present invention is in the range of 1.0 MPa to 1.8 MPa. However, the range of 1.5 MPa to 1.7 MPa is particularly advantageous. This is because the lamp voltage of the high-pressure discharge lamp according to the present invention can be increased by a relatively high xenon pressure, and white light can already be formed immediately after the ignition of the high-pressure discharge lamp by a high xenon pressure. .

As described above, the amount of halide in the internal space of the discharge vessel of the high-pressure discharge lamp according to the present invention is in the range of 8 mg to 15 mg per 1 cm ^{3 of} the discharge space volume, and the discharge space volume is from 0.015 cm ^3. It has a value in the range of 0.022 cm ³ . Particularly advantageously, in order to achieve a power consumption in the range of 22 W to 28 W in the substantially stable operating state of the high-pressure discharge lamp according to the invention, the amount of halide for the high-pressure discharge lamp according to the invention is It is in the range of 10 mg to 14 mg per cm ³ and the discharge space volume is in the range of 0.016 cm ³ to 0.019 cm ³ .

  In order to be able to use the high-pressure discharge lamp according to the present invention for a vehicle headlight that does not have a headlight washer, the main-pressure discharge lamp according to the present invention forms a luminous flux of 2000 lm or less during its operation. The high-pressure discharge lamp according to the invention can be configured.

III. In the following, the invention will be described in detail on the basis of advantageous embodiments.

1 shows a schematic cross-sectional view of a high-pressure discharge lamp according to an advantageous embodiment of the invention. FIG. 2 is a schematic partial view in which a discharge space of a discharge vessel of the high-pressure discharge lamp shown in FIG. 1 is enlarged. The relationship between the luminous flux and lamp voltage of a high-pressure discharge lamp and the ratio of zinc halide in the packing is shown.

An advantageous embodiment of the invention is a mercury-free halogen metal vapor high pressure discharge lamp with a power consumption of 25 W. This lamp is provided for use in a vehicle front headlight. The lamp has a discharge vessel 10 sealed on both sides, this discharge vessel 10 is made of quartz and has a discharge space 106 with a volume of 17 mm ³ , and an ionizable filling is hermetically sealed inside. Is enclosed. In the region of the discharge space 106, the outer contour of the discharge vessel 10 is formed in an elliptical shape, and in the region between the electrodes 11 and 12, the inner contour of the discharge vessel is formed in a cylindrical shape (see FIG. 2). Wanna) Therefore, the wall of the discharge vessel 10 is curved in a convex shape in the region of the discharge space 106, and between the electrodes 11 and 12, at the two end portions of the discharge space 106 in which the electrodes 11 and 12 are disposed. The wall thickness is greater than the wall thickness. The ratio of wall thickness D1 / D2 is in the range of 1.2 to 1.3. That is, the following relationship 1.2 ≦ D1 / D2 ≦ 1.3
Holds. Here, D1 represents the wall thickness of the discharge vessel 10 in the region between the electrodes 11 and 12, and D2 represents the wall thickness of the discharge vessel 10 in the end section of the discharge space 106 in which the electrodes 11 and 12 are disposed. Represent.

  At the center of the discharge space 106, the inner diameter of the discharge vessel is 2.2 mm and the outer diameter is 5.5 mm. The two end portions 101 and 102 of the discharge vessel 10 are sealed using molybdenum foil fusion sealing portions 103 and 104, respectively. Each of the molybdenum foils 103 and 104 has a length of 7.5 mm, a width of 2 mm, and a thickness of 25 μm. Two electrodes 11 and 12 are provided in the internal space of the discharge vessel 10, and a discharge arc is generated between the electrodes 11 and 12 during the operation of the lamp, thereby emitting light. The electrodes 11 and 12 are made of tungsten. The electrode thickness or diameter is 0.26 mm. Each of the electrodes 11 and 12 has a length of 6.5 mm. The actual distance between the electrodes 11 and 12, i.e. the distance measured by X-ray, is 3.7 mm, while the optical distance between the electrodes 11 and 12 or the optically acting distance is about 3.9 mm. It is. This difference between the actual distance between the electrodes 11 and 12 and the optical distance depends on the optical properties of the wall of the discharge vessel 10 in the region of the discharge space 106 (for example, a convex curve and an optical refractive index). to cause. The electrodes 11 and 12 are respectively connected via the molybdenum foil fusion sealing portions 103 and 104, the current supply portion 13 and the current feedback portion 17 opposite to the socket side, or the current supply portion 14 on the socket side. And electrically connected to the electrical terminal of the lamp socket 15 substantially made of plastic. The discharge vessel 10 is surrounded by a glass outer tube 16. The outer tube 16 has an extension 161 fixed in the socket 15. The discharge vessel 10 has a tubular elongated portion 105 made of quartz on the socket side, and a current supply portion 14 on the socket side extends in the elongated portion 105.

  A light-impermeable conductive coating portion 107 is provided on the surface region of the discharge vessel 10 facing the current feedback portion 17. The coating portion 107 extends in the longitudinal direction of the lamp over the entire length of the discharge space 106 and a part of the length of the sealed end portions 101 and 102 of the discharge vessel 10, approximately 50%. The coating portion 107 is provided on the outer surface of the discharge vessel 10 and extends from about 5% to 10% around the discharge vessel 10. However, the coating portion 107 may extend over 50% of the periphery of the discharge vessel 10, or even more than 50% of the periphery of the discharge vessel. Such a width embodiment of the coating part 107 has the advantage that the coating part 107 increases the efficiency of the high-pressure discharge lamp. This is because the coating 107 reflects a portion of the infrared radiation generated by the discharge to the discharge vessel, which causes the discharge below the electrodes to concentrate the ionizable fill metal halide during lamp operation. This is because the relatively cool area of the container 10 is selectively heated. The coating portion 107 is made of a doped tin oxide, for example, a tin oxide doped with fluorine or antimony, or a tin oxide doped with, for example, boron and / or lithium. The high pressure discharge lamp is operated in a horizontal posture, that is, the high pressure discharge lamp has electrodes 11 and 12 arranged on a horizontal plane, and the current feedback portion 17 extends below the discharge vessel 30 and the outer tube 16. As is present, the lamp is oriented. Details of this coating part 107 which functions as an ignition auxiliary part are described in EP 1 632 985 A1. The outer tube 16 is made of a material that absorbs ultraviolet radiation, such as quartz doped with cerium oxide and titanium oxide. A suitable glass composition for the outer tube glass is disclosed in EP 0 700 579 B1.

The filling enclosed in the discharge vessel is composed of xenon having a low filling pressure of 1.6 MPa, that is, a filling pressure measured at a temperature of 25 ° C., and iodides of sodium, scandium and indium. . The lamp temperature of the lamp is about 40V. The color temperature of the lamp is about 4500K. The total amount of sodium, scandium, zinc and indium halide or iodide as metal in the filling is 13.83 mg / cm ³ , ie 13.83 mg per cubic centimeter of discharge space volume, and sodium, scandium as metal. The proportions of zinc, indium and iodide are as follows with respect to the total amount of halide:
Sodium iodide: 43.4% by weight, equivalent to a loading of 6 mg / cm ³ Scandium iodide: 50.6% by weight, equivalent to a loading of 7 mg / cm ³ Zinc iodide: 5.8% by weight, 0.8% Equivalent to a filling amount of 8 mg / cm ³ Indium iodide: 0.2% by weight, equivalent to a filling amount of 0.03 mg / cm ³

This corresponds to a molar sodium to scandium ratio of 2.5: 1. The color rendering index of the halogen metal vapor high pressure discharge lamp is 65, and its light efficiency is 90 lm / W. The wall load is about 80 W / cm ² . The high pressure discharge lamp forms a luminous flux of 2000 lm or less and can therefore operate in a vehicle headlight without a headlight washer, for example to form day driving lights, fog lights or long beams.

  The halogen metal vapor high-pressure discharge lamp according to the invention has a rated output of 3 to 5 times to ensure rapid evaporation of the metal halide in the ionizable filling immediately after the ignition of the gas discharge in the discharge vessel. Or it is driven with a rated current. Immediately after the ignition of the gas discharge, the gas discharge is carried out almost exclusively by xenon. This is because at this point in time, only xenon is gaseous and present in the discharge vessel. The high-pressure discharge lamp therefore operates like a xenon high-pressure discharge lamp at this point and also during the so-called start-up phase during which the metal halide of the ionizable filling transitions to the evaporation phase, and the light emission is also an electrical discharge. The characteristics, in particular the voltage drop over the discharge interval, are also determined only by the xenon and electrode spacing. Only when the above-mentioned iodide of the ionizable filling has evaporated and this iodide is involved in the discharge, the lamp operates at a rated output of 25 W and an operating voltage of 40 V, a nearly stable operating state of the lamp Has been achieved. Therefore, the concept of operating voltage represents the operating voltage of the high-pressure discharge lamp during a substantially stable operation.

  The invention is not limited to the embodiments described in detail above. For example, the fill can include thulium iodide in addition to sodium, scandium and indium iodide as metals. Furthermore, other halides such as bromides or chlorides of these metals can also be used in the filling instead of or in addition to the metal iodides mentioned above.

Claims (15)

Filled with a xenon and mercury-free filling, containing at least sodium, scandium and zinc halides, and filled with electrodes (11, 12) for generating a gas discharge. In a high-pressure discharge lamp for a vehicle headlight comprising an airtightly closed discharge vessel (10) having a discharge space (106)
The filling contains zinc halide at a rate ranging from 0 mg to 1 mg per cm ^{3 of} discharge space volume, and the amount of the halide present in the discharge space (106) of the discharge vessel (10). Is in the range of 8 mg to 15 mg per cm ^{3 of} discharge space volume,
The xenon low-temperature filling pressure is in the range of 1.0 MPa to 1.8 MPa, and
The high-pressure discharge lamp according to claim 1, wherein the volume of the discharge space (106) of the discharge vessel (10) has a value in the range of 0.015 cm ³ to 0.022 cm ³ . 2. The high pressure according to claim 1, wherein the proportion of zinc halide is greater than 0 mg per cm ^{3 of the} discharge space volume, advantageously in the range of 0.1 mg to 1.0 mg per cm ^{3 of the} discharge space volume. Discharge lamp.   The high-pressure discharge lamp according to claim 1 or 2, wherein the filling further contains indium halide, and a ratio of the indium halide in the filling is 3.0% by weight or less of the amount of halide.   4. The high-pressure discharge lamp according to claim 1, wherein a ratio of sodium halide in the filling is in a range of 30 wt% to 50 wt% of a total amount of halide. 5.   The high-pressure discharge lamp according to any one of claims 1 to 4, wherein the proportion of scandium halide in the filling is in the range of 30% to 60% by weight of the total amount of halide.   6. The filling according to claim 1, further comprising thulium halide, wherein the proportion of thulium halide in the filling is in the range of 10% to 30% by weight of the total amount of halide. The high pressure discharge lamp according to item. The discharge vessel (10) has an elliptical outer contour in the range of the discharge space (106), and has a cylindrical inner contour in the region between the electrodes (11, 12). ,
The ratio of the wall thickness of the discharge vessel (10) is as follows:
1.0 ≦ D1 / D2 ≦ 1.4
Where D1 is the wall thickness of the discharge vessel (10) in the region between the electrodes, and D2 is the end of the discharge space (106) in which the electrodes (11, 12) are disposed. The high-pressure discharge lamp according to any one of claims 1 to 6, which represents a wall thickness of the discharge vessel (10) in a section. The following relationship with respect to the wall thickness of the discharge vessel (10):
1.2 ≦ D1 / D2 ≦ 1.3
The high-pressure discharge lamp according to claim 7, wherein:   The discharge vessel (10) has an inner diameter in the range of 2.0 mm to 2.7 mm in the region between the electrodes (11, 12) and is in the range of 5.0 mm to 6.0 mm. The high-pressure discharge lamp according to claim 7 or 8, having an outer diameter.   The discharge vessel (10) has an inner diameter in the range of 2.1 mm to 2.4 mm in the region between the electrodes (11, 12) and is in the range of 5.3 mm to 5.7 mm. The high-pressure discharge lamp according to claim 9, having an outer diameter.   The electrodes (11, 12) are rod-shaped and have a diameter in the range of 0.20 mm to 0.30 mm, preferably in the range of 0.25 mm to 0.27 mm. The high-pressure discharge lamp according to any one of 1 to 10. The amount of halide in the discharge space (106) of the discharge vessel (10) is in the range of 10 mg to 14 mg per cm ^{3 of the} discharge space volume. High pressure discharge lamp.   The high-pressure discharge lamp according to any one of claims 1 to 12, wherein the xenon low-temperature filling pressure is in a range of 1.6 MPa to 1.8 MPa. 14. The high-pressure discharge lamp according to claim 1, wherein the volume of the discharge space (106) of the discharge vessel (10) has a value in the range of 0.016 cm ³ to 0.019 cm ³ .   15. The high pressure discharge lamp according to any one of the preceding claims, wherein the high pressure discharge lamp is configured for power consumption in the range of 22W to 28W.

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