JP2011029134A - Discharge lamp device, discharge lamp, and lighting circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp device, a discharge lamp and a lighting circuit with little starting variation.
[Solution]
The discharge lamp device of the present invention includes an inner tube 1 having a light emitting portion 11 and a seal portion 12 having a discharge space 111 therein, a discharge medium sealed in the discharge space 111, and an electrode mount sealed in the seal portion 12. 3 and an outer tube provided so as to cover the light emitting unit 11, and a lighting circuit 105 for lighting the discharge lamp 101, and the inner tube 1 of the discharge lamp 101 and the outer tube 1. Gas is sealed in a space 51 formed between the tube 5 and a conductive film 9 is formed on the surface of the seal portion 12 set on the high voltage side. A negative high voltage pulse is generated by the lighting circuit 105 at the start. It produces | generates and it applies to the discharge lamp 101, It is characterized by the above-mentioned.
[Selection] Figure 4

Description

  The present invention relates to a discharge lamp device, a discharge lamp, and a lighting circuit used for an automobile headlamp and the like.

  As is known in Japanese Patent No. 3596812 (hereinafter referred to as Patent Document 1), a discharge lamp used for automobile headlamps has a double tube structure including an inner tube and an outer tube. Yes. The inner tube is composed of a light emitting portion and seal portions formed at both ends thereof. A rare gas or a metal halide is sealed in the light emitting portion, and an electrode mount is sealed in the seal portion.

  This type of discharge lamp requires a voltage of several kV to several tens of kV in order to start the lamp, and it is known that starting is difficult. In view of this, as described in Patent Document 1, an invention has been proposed in which the startability of a lamp is improved by enclosing a gas capable of dielectric barrier discharge in a space formed by an inner tube and an outer tube.

  JP 2003-529194 A (hereinafter referred to as Patent Document 2), JP 2006-80078 (hereinafter referred to as Patent Document 3), JP 2007-42369 A (hereinafter referred to as Patent Document 4), and JP 2008. Japanese Patent No. 527623 (hereinafter referred to as Patent Document 5) proposes an invention that improves the startability of the lamp by forming a conductive film on the outer surface of the light emitting part or the seal part.

Japanese Patent No. 3596812 JP 2003-529194 A JP 2006-80078 A JP 2007-42369 A JP 2008-527623 A

  By adopting the inventions of Patent Documents 1 to 5, the startability of the lamp can be improved. However, it has been found that even if these inventions are adopted, the variation in the starting voltage is large. If the starting voltage varies greatly, a lamp that does not start is generated.

  An object of the present invention is to provide a discharge lamp device, a discharge lamp, and a lighting circuit with little start-up variation.

  In order to achieve the above object, a discharge lamp device according to the present invention comprises a light emitting part having a discharge space inside and an inner tube having a seal part, a discharge medium sealed in the discharge space, and a seal on the seal part. A discharge lamp device comprising: a discharge lamp comprising: an electrode mount formed; an outer tube provided so as to cover the light emitting portion; and a lighting circuit for lighting the discharge lamp. Gas is sealed in the space formed between the inner tube and the outer tube, and a conductive film is formed on the surface of the inner tube. The high-pressure pulse is generated and applied to the discharge lamp.

  According to the present invention, it is possible to provide a discharge lamp device, a discharge lamp, and a lighting circuit with little start-up variation.

The figure for demonstrating the discharge lamp apparatus of the 1st Embodiment of this invention. The figure for demonstrating a discharge lamp. The figure for demonstrating the state which rotated the discharge lamp of FIG. 2 90 degrees. The figure for demonstrating a negative polarity high voltage | pressure pulse. The figure for demonstrating the measuring method of a pulse waveform. The figure for demonstrating distribution of the starting voltage Vs when a positive polarity and negative polarity high voltage pulse is applied about the lamp | ramp of an Example and a prior art example. The figure for demonstrating distribution of the starting voltage Vs when a positive polarity and a negative polarity high voltage pulse are applied about the lamp | ramp which has not formed the electroconductive film. The figure for demonstrating the negative polarity high voltage | pressure pulse whose fall time is 300 ns. The figure for demonstrating the modification of an electroconductive film. For explaining an example of both high-voltage configurations (a positive pulse with a peak value of +17 kV and a rise time of 86 ns on the first side, a negative pulse of -16 kV with a peak value of -16 kV and a fall time of 77 ns on the second side) Figure.

(First embodiment)
The discharge lamp of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram for explaining a discharge lamp device according to a first embodiment of the present invention.

  The discharge lamp device includes a discharge lamp 101, a reflector 102, a light shielding control plate 103, a lens 104, and a lighting circuit 105, and is used with a tube axis arranged in a substantially horizontal state.

  The discharge lamp 101 is a so-called D4 type discharge lamp used for an automobile headlamp as shown in FIGS. 2 and 3, and has an inner tube 1 as a main part. The inner tube 1 has an elongated shape in the tube axis direction, and a substantially elliptical light emitting portion 11 is formed near the center thereof. A plate-like seal portion 12 formed by a pinch seal is formed at both ends of the light emitting portion 11, and a cylindrical portion 14 is continuously formed at both ends via a boundary portion 13. The inner tube 1 is preferably made of a material having heat resistance and translucency, such as quartz glass. Further, the seal portion 12 may be formed by a shrink seal.

Inside the light emitting portion 11, a discharge space 111 having a substantially cylindrical shape at the center and a tapered shape at both ends is formed. The volume of the discharge space 111, in the case of vehicle headlights ^are, 10mm ^{3 ~40mm 3,} further it is appropriate to a 20mm ³ ~30mm ^3. A discharge medium is enclosed in the discharge space 111. The discharge medium is composed of a metal halide 2 and a rare gas.

  The metal halide 2 is composed of a halide such as sodium, scandium, zinc, or indium. Iodine is optimal as the halogen bonded to these metal halides, but bromine, chlorine, and the like may be combined. The combination of metal halides is not limited to this, and tin or cesium halides may be added.

  The rare gas is composed of xenon. The sealing pressure of the rare gas can be adjusted depending on the purpose. For example, in order to improve the characteristics such as the total luminous flux, it is desirable that the sealing pressure is 12 atm or more at normal temperature (25 ° C.). However, the upper limit is about 20 atm at present in terms of manufacturing. The pressure of the rare gas is calculated by destroying the boundary between the light emitting unit 11 and the seal unit 12 in water, collecting and measuring the gas in the discharge space 111, and then measuring the volume of the discharge space 111. be able to. In addition to xenon, neon, argon, krypton, or the like can be used as a rare gas, or a combination thereof can be used.

  Here, the discharge medium does not substantially contain mercury. This “substantially free of mercury” means that the amount of mercury enclosed is optimally 0 mg, but it is almost equal to that of a conventional mercury-containing discharge lamp. This means that an amount of mercury, for example, less than 2 mg per ml, preferably 1 mg or less, is allowed to be contained.

  The electrode mount 3 is sealed to the seal portion 12. The electrode mount 3 includes a metal foil 31, an electrode 32, a coil 33 and a lead wire 34.

  The metal foil 31 is a thin metal plate made of, for example, molybdenum.

  The electrode 32 is, for example, an electrode made of so-called tritated tungsten obtained by doping tungsten with thorium oxide. One end of the metal foil 31 is overlapped and connected to the end of the light emitting unit 11 side, and the other end is disposed in the discharge space 111 so as to face each other with a predetermined distance between the electrodes. Yes. The distance between the electrodes is preferably 4.0 mm to 4.4 mm in terms of appearance in the case of an automotive headlamp. The electrode shape is not limited to a straight rod shape, but may be a non-straight rod shape having a large tip diameter or a shape in which the size of the pair of electrodes is different, such as a DC lighting type. The electrode material may be pure tungsten, doped tungsten, rhenium tungsten, or the like.

  The coil 33 is a metal wire made of, for example, doped tungsten, and is spirally wound around the axis of the shaft portion of the electrode 32 sealed to the seal portion 12. As the coil design, it is preferable that the coil wire diameter is 30 μm to 100 μm and the coil pitch is 600% or less.

  The lead wire 34 is a metal wire made of molybdenum, for example. One end thereof is overlapped and connected to the metal foil 31 on the opposite side with respect to the light emitting unit 11, and the other end extends to the outside of the inner tube 1 along the tube axis. Among them, one end of an L-shaped support wire 35 made of nickel, for example, is connected to the lead wire 34 extending to the front end side of the lamp by laser welding. For example, a sleeve 4 made of ceramic is attached to the support wire 35 at a portion parallel to the inner tube 1.

  A cylindrical outer tube 5 is provided concentrically with the inner tube 1 on the outer side of the inner tube 1 configured as described above. These inner and outer pipes are connected by welding both ends of the outer pipe 5 near the cylindrical portion 14 of the inner pipe 1. Nitrogen is enclosed in a space 51 formed between the inner tube 1 and the outer tube 5. The outer tube 5 is preferably made of a material having a thermal expansion coefficient close to that of the inner tube 1 and having an ultraviolet blocking property. For example, quartz glass to which an oxide such as titanium, cerium, or aluminum is added is used. can do.

  A socket 6 is connected to one end of the inner tube 1 to which the outer tube 5 is connected. These connections are made by attaching a metal band 71 to the outer peripheral surface of the outer tube 5 and sandwiching the metal band 71 with a metal tongue piece 72 formed protruding from the socket 6. A bottom terminal 81 is formed at the bottom of the socket 6, and a side terminal 82 is formed at the side. The lead wire 34 and the support wire 35 are connected to the bottom terminal 81 and the side terminal 82, respectively. Yes.

  A conductive coating 9 is formed on the surface of the seal portion 12 on the socket 6 side so as to face the metal foil 31. The conductive coating 9 is conductive (for example, the resistance of the film is 100 MΩ or less, preferably 50 to 100 kΩ. The resistance value is a tester in which the surface of the film having a thickness of 150 nm is set to 1.5 mm between the terminals. It is desirable to use a material having translucency and heat resistance. For example, indium oxide, tin oxide, zinc oxide, ITO which is an oxide of indium and tin, AZO in which zinc oxide is doped with aluminum oxide, GZO in which zinc oxide is doped with gallium oxide, etc. and fluorine in these A material doped with gallium, antimony, or the like can be used. In the present invention, it is particularly desirable to use inexpensive tin oxide.

The conductive coating 9 is not limited to a perfect circle, but may be an ellipse or a polygon, or may be a combination of these shapes or a shape where they are connected to each other. The total area of the resulting conductive coating 9 is preferably 5 mm ² or more and 50 mm ² or less. Further, the conductive coating 9 is not limited to the surface of the seal portion 12 facing the metal foil 31, and is, for example, the surface of the seal portion 12 on the electrode 32 or the lead wire 34, the side surface of the seal portion 12, etc. Also good. Further, the conductive coating 9 may be formed not only on the surface of the seal portion 12 but also on the inner surface of the outer tube 5.

  The reflector 102 is a parabolic metal member provided to reflect the light generated by the discharge lamp 101 to the front side. An opening is formed in the vicinity of the center, and the front end portion of the socket 6 of the discharge lamp 101 is fixed at the opening end so that the light emitting portion 11 is located inside the reflector 102.

  The light shielding control plate 103 is a metal member provided in order to form a light distribution called a cut line. The light shielding control plate 103 is movable, and can be switched from a low beam to a high beam by tilting forward on the bottom side.

  The lens 104 is a convex lens provided to collect the light reflected by the reflector 102 to form a desired light distribution, and is arranged at the opening on the tip side of the reflector 102.

  The lighting circuit 105 is a circuit for starting and lighting the discharge lamp 101. The lighting circuit 105 includes an igniter circuit 1051 and a ballast circuit 1052, and the bottom terminal 81 of the discharge lamp 101 is on the high voltage side, and the side terminal 82 is on the low voltage side. Connected to be on the side.

  The igniter circuit 1051 is a circuit that generates a high-voltage pulse of about 30 kV, applies it to the lamp, and causes the dielectric breakdown between the pair of electrodes 32 to start the discharge lamp 101. The igniter circuit 1051 includes a transformer, a capacitor, a gap, a resistor, and the like. ing. In the present invention, a negative high-pressure pulse is applied to the high-pressure side of the discharge lamp 101, that is, the seal portion 12 side where the conductive coating 9 is formed. “Negative high-voltage pulse” refers to a pulse generated on the negative side immediately after application as shown in FIG. 4, and such a pulse is generated by winding the winding direction of the transformer in reverse. can do.

  The ballast circuit 1052 is a circuit for maintaining the lighting of the discharge lamp 101 started by the igniter circuit 1051, and includes a DC / DC conversion circuit, a DC / AC conversion circuit, a current / voltage detection circuit, a control circuit, and the like. ing. The ballast circuit 1052 is set so that, for example, about 30 to 75 W, which is more than twice the stable power, is input to the discharge lamp 101 immediately after startup, and about 15 to 35 W is input when stable.

One specification of the embodiment of the discharge lamp of the present invention is shown below.
(Example)
Light emitting part 11; made of quartz glass, inner volume of discharge space 111 = 26 mm ³ , maximum inner diameter = 2.5 mm, maximum outer diameter = 6.2 mm, longitudinal sphere length = 7.8 mm,
Seal portion 12; wall thickness = 2.4 mm, width = 4.1 mm,
Metal halide 2; ScI ₃ , NaI, ZnI ₂ , InBr (= 1: 1.5: 0.4: 0.01), total = 0.4 mg,
Noble gas; xenon, gas pressure = 13 atm,
Mercury; 0 mg,
Metal foil 31; made of molybdenum, length × width = 6.5 mm × 1.5 mm, thickness = 0.02 mm,
Electrode 32: made of triated tungsten, diameter = 0.38 mm, distance between electrodes on appearance = 4.32 mm,
Coil 33; made of doped tungsten, wire diameter = 60 μm, pitch = 250%,
Lead wire 34; made of molybdenum, diameter = 0.4 mm,
Outer tube 5; inner diameter = 7.0 mm, wall thickness = 1.0 mm,
Gas in the space 51; nitrogen, gas pressure = 0.1 atm,
Conductive coating 9; tin oxide is formed on each of the front and back surfaces of the high pressure side seal portion 12 by 7 mm ² (total area 14 mm ² ),
Lighting circuit 105; at startup, peak value = 24 kV, fall time (time of high-pressure pulse until pulse waveform changes from 10% to 90% with respect to peak value) = 110 ns = 110 ns Apply a pulse, set to 75W immediately after startup, then gradually reduce the power, and to 35W when stable. The peak value and fall time of the high-pressure pulse are measured from the waveform obtained by connecting the oscilloscope OS to the circuit part connected to the high-pressure side of the lamp, as shown in FIG.

  A test for measuring the starting voltage Vs and its variations was performed on each of the discharge lamp device of this example and a plurality of discharge lamp devices (hereinafter, conventional examples) that apply a positive high-pressure pulse. The results are shown in FIGS. 6 (a) and 6 (b), respectively.

  As can be seen from the results, the average value of the starting voltage Vs is the same in both the example and the conventional example, or slightly lower in the conventional example. However, as apparent from the value of the standard deviation, the variation in the starting voltage Vs is lower in the example. This is because, in the lamp in which the gas is sealed in the space 51 as in the present invention and the conductive coating 9 is formed on the surface of the high pressure side seal portion 12, a dielectric barrier discharge is generated by applying a high voltage pulse. Although starting is assisted, it is considered that the γ effect of emitting secondary electrons from the surface of the conductive film 9 was obtained by making the high voltage pulse negative. That is, in the example, since the generation of dielectric barrier discharge is assisted, it is considered that the starting probability is increased and the variation is reduced. If the start-up variation is reduced in this manner, it is not necessary to design a transformer with a margin for pulse output, so that the transformer can be reduced in size and cost.

  Incidentally, FIG. 7A shows a starting voltage distribution when a positive high-pressure pulse is applied to a lamp without the conductive film 9 and FIG. 7B shows a negative high-voltage pulse. From this result, it can be seen that even when a negative high voltage pulse is applied to the lamp, the average value and variation of the starting voltage Vs are worse than those of the positive voltage. From this, in the lamp in which the gas is sealed in the space 51 and the conductive coating 9 is formed on the surface of the high pressure side seal portion 12, it is possible to obtain an excellent effect by applying a negative high voltage pulse. It can be said that the result of 6 (a) is unexpected. In addition, as shown in FIG. 2, a higher effect can be expected when the conductive coating 9 is formed on both surfaces of the seal portion 12.

  Next, the change in the starting voltage when the fall time of the negative high voltage pulse applied to the lamp was changed was tested. As a result, it was found that the average starting voltage Vs and the variation change depending on the fall time. For example, when a high voltage pulse having a fall time of about 300 ns as shown in FIG. 8 is applied, the average value of the starting voltage Vs is slightly lower than that of about 110 ns, but the standard deviation is 1.5 times as large. Become. In other words, when it is desired to reduce the start-up variation, it is preferable that the fall time is short. From the results of various tests, the fall time of the negative high voltage pulse is preferably 180 ns or less, and more preferably 110 ns or less.

  Therefore, in the present embodiment, nitrogen is sealed as a gas in the space 51 formed between the inner tube 1 and the outer tube 5 of the discharge lamp 101, and the surface of the seal portion 12 set on the high pressure side is electrically conductive. In order to assist the generation of dielectric barrier discharge that assists the starting of the lamp by forming the conductive film 9 and generating a negative high-pressure pulse by the lighting circuit 105 at the time of starting and applying it to the discharge lamp 101. Therefore, the starting variation of the lamp can be reduced. At this time, the start-up variation can be further reduced by setting the fall time of the negative high voltage pulse to 180 ns or less.

  The present invention is more effective when combined with the following configuration.

(1) Argon is sealed in the space 51.
Since argon is a gas that is easily ionized, that is, has a low ionization energy as compared with nitrogen sealed in the examples, when a negative high-voltage pulse is applied at the time of starting, the amount of secondary electrons emitted increases, and the dielectric barrier Discharge tends to occur. Note that a rare gas such as neon or xenon also corresponds to a gas having low ionization energy. However, neon is too low in temperature of the light emitting unit 11 and easily escapes from the space 51 during the lifetime, and xenon and krypton are emitted from the light emitting unit 11. This is not suitable for practical use because the temperature of the water rises too much. On the other hand, argon is optimal because the startability can be further improved by the γ effect while maintaining the temperature of the light emitting unit 11 at a certain level. Argon is not limited to a simple substance, but is included in this range when the majority, for example, 90% or more of the whole is argon. The gas pressure is preferably 0.3 atm or less, more preferably 0.1 atm or less.

(2) The conductive film 9 provided with the raised portions 91 and / or the serrated portions 92 is formed.
As shown in FIG. 9, a protruding portion 91 extending from the surface of the conductive coating 9 in a direction perpendicular to the seal portion 11 than the flat portion of the coating, and a serrated sawtooth like a sawtooth at the edge. By forming the shape portion 92, the electric field concentrates on the tip portion thereof, and it becomes easier to induce the dielectric barrier discharge in the space where the electron concentration is increased by the γ effect. Either the raised portion 91 or the serrated portion 92 is effective, but it is desirable to form both. In addition, such a conductive film 9 is formed by dropping a conductive solution 9 ′ having a low surface tension formed by mixing tin oxide, butyl acetate, or the like from a certain height with respect to the surface of the seal portion 12 using a dispenser 101 or the like. It can be formed by firing.

(3) A high-voltage configuration in which a positive high-voltage pulse is applied to one electrode mount 3 and a negative high-pressure pulse is applied to the other electrode mount 3 at the time of starting.
As shown in FIG. 10, by applying a positive high voltage pulse to one electrode mount 3 and a negative high voltage pulse to the other electrode mount 3 at the time of starting, the circuit is maintained while maintaining good startability. It is possible to reduce the size and to easily ensure insulation. For example, in the case of a lamp that requires a high-pressure pulse of 20 kV for starting when it is applied only to one side, it starts only by applying a high-voltage pulse of about 10 kV, which is about half of that to one side. Can be substituted. Since such a transformer is small, the degree of freedom in the layout design of the circuit members is increased, and insulation can be easily ensured. This merit is limited in size, such as a type of headlamp in which the discharge lamp 101 and the igniter circuit 1051 are integrated, and a type of headlamp in which the ballast circuit 1052 is also integrated. It is particularly large in some lamp devices. In the case of using both high voltage configurations, it is desirable that the positive and negative high voltage pulses have the same phase and have a waveform that is inverted only in polarity. Further, it is desirable that the conductive coating 9 be formed on the surfaces of both seal portions 11.

  Here, the peak values of the positive and negative high voltage pulses need not be the same, and may be changed as desired. For example, the peak value of the high voltage pulse on the 1st side (socket side) may be higher than the peak value of the high voltage pulse on the 2nd side (support wire side). In the case of an automotive headlamp, a metal member called a shade for light distribution control is arranged near the tip of the lamp, and when a high voltage pulse is applied to the support wire 34 side, a voltage leaks to the shade. However, if the ratio of the peak value of the high-pressure pulse on the 2nd side (support wire side) is lowered, the occurrence of leakage can be suppressed.

DESCRIPTION OF SYMBOLS 101 Discharge lamp 1 Inner tube 11 Light emission part 111 Discharge space 12 Seal part 3 Electrode mount 5 Outer tube 51 Space 9 Conductive film 105 Lighting circuit

Claims (7)

An inner tube having a light emitting part having a discharge space inside and a seal part, a discharge medium sealed in the discharge space, an electrode mount sealed in the seal part, and the light emitting part are provided so as to cover A discharge lamp with an outer tube;
In a discharge lamp device comprising a lighting circuit for lighting the discharge lamp,
Gas is sealed in the space formed between the inner tube and the outer tube of the discharge lamp, and a conductive coating is formed on the surface of the inner tube,
In the lighting circuit, a negative high pressure pulse is generated at start-up and applied to the discharge lamp.   The discharge lamp includes a pair of seal portions at both ends of the light emitting portion, and the lighting circuit is connected so that one of the seal portions is on the high pressure side and the other seal portion is on the low pressure side, The discharge lamp device according to claim 1, wherein the coating is formed on a surface of the seal portion on a high pressure side.   The discharge lamp device according to claim 1 or 2, wherein a fall time of the negative high-pressure pulse is 180 ns or less.   The discharge lamp apparatus according to any one of claims 1 to 3, wherein the gas is argon.   The discharge lamp includes a pair of seal portions at both ends of the light emitting portion, and electrode mounts are sealed inside the pair of seal portions, respectively. The pulse is generated, and a positive high voltage pulse is applied to one of the electrode mounts, and a negative high voltage pulse is applied to the other electrode mount. Discharge lamp device. An inner tube having a light emitting part having a discharge space inside and a seal part, a discharge medium sealed in the discharge space, an electrode mount sealed in the seal part, and the light emitting part are provided so as to cover In a discharge lamp comprising an outer tube,
Gas is sealed in a space formed between the inner tube and the outer tube, and a conductive coating is formed on the inner tube, and a negative high-pressure pulse is applied at the time of starting. A discharge lamp characterized by that. An inner tube having a light emitting part having a discharge space inside and a seal part, a discharge medium sealed in the discharge space, an electrode mount sealed in the seal part, and the light emitting part are provided so as to cover An outer tube,
In a lighting circuit for lighting a discharge lamp in which a gas is sealed in a space formed between the inner tube and the outer tube and a conductive film is formed on the surface of the inner tube. ,
A lighting circuit, wherein a negative high-pressure pulse is generated at the time of starting and applied to the discharge lamp.

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