JP2006019054A - Metal halide lamp and lighting device - Google Patents

Abstract

【Task】
A mercury-free metal halide lamp that suppresses the occurrence of flickering of light emission and an illumination device using the same.
[Solution]
The metal halide lamp MHL includes a translucent airtight container 1 having an internal volume of 0.5 cc or less; a pair of electrodes 1b and 1b sealed in a translucent airtight container 1 with a distance between electrodes of 5 mm or less; and scandium (Sc), a halide of a plurality of metals selected from the group of sodium (Na), indium (In), zinc (Zn) and rare earth metals, and a rare gas containing mercury (Hg). A discharge medium enclosed in a light-tight airtight container; and a tube wall load of 60 W / cm ² or more, and water in the light-tight airtight container is A (ng), and a rectangular wave AC voltage is The following formula is satisfied when the lighting frequency at the time of lighting when applied is f (Hz).
A / √f ≦ 4.5
[Selection]
FIG.

Description

  The present invention relates to a mercury-free metal halide lamp and an illumination device using the same.

  A so-called mercury-free metal halide lamp (hereinafter referred to as “mercury-free lamp” for the sake of convenience) that essentially does not enclose mercury is already known (see, for example, Patent Document 1). Mercury-free lamps contain metal halides, such as zinc (Zn), which have a relatively high vapor pressure and do not easily emit light in the visible region, instead of mercury that is sealed as a buffer material for lamp voltage formation. It is common.

  Mercury-free lamps are particularly expected and developed as a light source for automotive headlamps that are trying to eliminate the use of environmentally hazardous substances. Since this metal halide lamp is generally thinner than a mercury-containing metal halide lamp (hereinafter referred to as “mercury-containing lamp” for the sake of convenience), the discharge arc is likely to be unstable, and thus flickering of light is likely to occur. It is accompanied by the problem. For this reason, it is necessary to add a special measure that was unnecessary in the case of a lamp containing mercury.

By the way, it has been conventionally known to reduce impurities existing inside a light-transmitting hermetic container of a high-pressure discharge lamp (see, for example, Patent Documents 2 to 5). In Patent Document 2, the maximum intensity of the spectral spectrum of hydrogen, oxygen, and their compounds existing in the light emitting part when a glow discharge is performed by supplying a current of 3 mA in the manufacture of a mercury lamp or a metal halide lamp, By reducing the spectral spectrum intensity to 1/1000 or less, the impurities are reduced, blackening and devitrification are suppressed, and lamp life is increased. In Patent Documents 3 and 4, in the production of a mercury-containing lamp, glass processing is performed using a propane oxygen burner or a plasma torch, or high-temperature heating is performed in vacuum after processing to release it as H ₂ O. Impurities are reduced to suppress blackening and devitrification, and to increase lamp life. In Patent Document 5, high-temperature vacuum heat treatment is performed at 1200 ° C. for 6 hours in the manufacture of a high-pressure discharge lamp enclosing mercury, halogen, and a rare gas.
JP 11-238488 A JP 11-329350 A JP 09-102277 A Japanese Patent Laid-Open No. 09-102278 Japanese Patent Laid-Open No. 02-220328

  The inventor has configured the mercury-free lamp so that the amount of moisture present inside the translucent airtight container and the lighting frequency when the rectangular wave AC voltage is applied to light up satisfy a predetermined condition. The present inventors have found that flickering of light emission can be effectively suppressed. The present invention has been made based on this finding.

  An object of the present invention is to provide a mercury-free metal halide lamp that suppresses the occurrence of flickering of light emission and an illumination device using the same.

A metal halide lamp according to a first aspect of the present invention is a translucent airtight container having an internal volume of 0.5 cc or less; a pair of electrodes sealed in a translucent airtight container with an interelectrode distance of 5 mm or less; Contains a plurality of metal halides selected from the group of scandium (Sc), sodium (Na), indium (In), zinc (Zn) and rare earth metals, and contains noble gases and is essentially free of mercury (Hg). A discharge medium enclosed in a translucent airtight container; a tube wall load of 60 W / cm ² or more, and moisture in the translucent airtight container as A (ng), a rectangular wave AC voltage It is characterized in that the following equation is satisfied, where f (Hz) is the lighting frequency when lighting is applied.

A / √f ≦ 4.5
In the present invention, the moisture A (ng) in the translucent airtight container can be measured by gas analysis using an API-MS analysis method. That is, the weight of the water-based gas in the gas released when the translucent airtight container is broken at 200 ° C. in a sealed space is measured. The obtained detection value has a correlation with the total amount of water present inside the translucent airtight container, so although the moisture contained in the metal halide cannot be detected, the amount of water in the translucent airtight container is It can be used as a prescribed index.

  On the other hand, the lighting frequency when the rectangular wave AC voltage is applied for lighting is the frequency of the rectangular wave AC voltage supplied from the lighting circuit to the metal halide lamp, and is preferably 4 kHz or less. In the present invention, the reason why the rectangular wave voltage is applied to light the metal halide lamp is that the rectangular wave voltage is less likely to cause light emission flicker than the sine wave voltage, and the circuit configuration of the lighting circuit is simplified. Because. In addition, the rectangular wave voltage includes not only a complete rectangular wave but also a waveform that is partially stepped, such as a pulse portion partially overlapping.

  Next, the operation of the present invention will be described. In the present invention, the flickering of light emission is proportional to the moisture inside the translucent airtight container from the above formula, and inversely proportional to the 1/2 power of the lighting frequency when the rectangular wave AC voltage is applied to light up. It can be understood that the flickering of the light emission is suppressed within an allowable range when the ratio of the former to the latter is 4.5 or less. Therefore, flickering of light emission can be suppressed within an allowable range by reducing the moisture amount relative to a certain lighting frequency or increasing the frequency relative to a certain moisture amount. On the other hand, when the amount of moisture increases or the lighting frequency decreases, the flickering of light emission is likely to occur. The mechanism of the occurrence of flickering of light emission is estimated as follows.

That is, when there is a lot of moisture, a large amount of gas such as hydrogen (H ₂ ), oxygen (O ₂ ), and OH that inhibits the discharge is generated, so that the discharge becomes unstable and the discharge arc is physically undulated. Looks like flickering. In addition, since the dielectric breakdown voltage of the gas containing that of the discharge medium inside the translucent airtight container is increased by these gases, the arc disappears once in the current zero period when the polarity of the alternating current flowing between the pair of electrodes is reversed, The phenomenon of firing (re-firing) occurs after the polarity is reversed again. This phenomenon often occurs at a random cycle of alternating current, and may be perceived as flickering of light emission depending on the generation timing. In addition, since the arc disappears instantaneously, the next time it is re-ignited, an arc spot is formed at a different electrode position, and as a result, the phenomenon that the arc spot moves easily occurs. Caused flickering of light emission occurs. When there is a lot of moisture in this way, light emission flickers also occur due to several mechanisms.

  Next, when the lighting frequency when the rectangular wave AC voltage is applied and the metal halide lamp is turned on is low, the above-described flickering of light emission generated in association with the polarity inversion is easily perceived. That is, since the polarity reversal cycle is long, the flicker cycle that occurs is close to the cycle that the eyes can respond to. In addition, when the lighting frequency is low, it is considered that the current zero period at the time of polarity reversal is long or the arc extinction period is long due to some factor.

  By the way, in this invention, the removal of the water | moisture content which exists in the inside of a translucent airtight container can be performed by employ | adopting various known means suitably. However, it is practically difficult to completely remove moisture and less than 1 ng cannot be achieved. In the case of 1 ng of the minimum water content, the lighting frequency when A / √f in the above formula is smaller than 0.016 is larger than 4 kHz. However, at a frequency higher than this, when a rectangular wave AC voltage is generated using an inexpensive switching element, since the switching loss described later increases, the luminous efficiency including the lighting circuit decreases to a level that cannot be ignored. It is preferable that a lower limit value is added to the formula so that 0.016 ≦ A / √f ≦ 4.5.

Next, in the present invention, in addition to the above requirements, (1) the inner volume of the translucent airtight container is 0.5 cc or less, (2) the distance between the electrodes is 5 mm or less, and (3) the metal halide of the discharge medium is A halide of a plurality of metals selected from the group of scandium (Sc), sodium (Na), indium (In), zinc (Zn) and rare earth metals, (4) the discharge medium essentially contains mercury And (5) the lamp power per unit inner surface area of the hermetic container, that is, the tube wall load is 60 (W / cm ² ) or more, is also stipulated as a requirement for the following reasons. It is. That is,
(1) The inner volume of the translucent airtight container being 0.5 cc or less means that the rated lamp power is not only a small metal halide lamp for automobile headlamps but also a relatively rated lamp for liquid crystal projections, for example. This is because the present invention is effective even in a metal halide lamp with high electric power. In the case of a metal halide lamp for liquid crystal projection, the internal volume is 0.4 cc or less and the rated lamp power is about 80 to 150 W.

  (2) Since the metal halide lamp having an interelectrode distance of 5 mm or less is used for a headlamp or a projection lamp that is required to have a good rise in luminous flux immediately after starting or is used for a preferable application, the present invention is effective. Is. As a metal halide lamp for automobile headlamps, a distance between electrodes of 4.2 mm is standardized. On the other hand, 2 mm or less is suitable for liquid crystal projection.

  (3) A metal halide lamp suitable for various applications can be obtained by using a plurality of metal halides selected from the above group as the discharge medium. Among the metals in the above group, scandium (Sc) and sodium (Na) generate white light emission with high efficiency, particularly in the combination thereof, and can be employed as a main light-emitting substance for visible light. Indium (In) and zinc (Zn) emit blue light and can be used for chromaticity adjustment. Moreover, since zinc has a relatively high vapor pressure, it can be used for lamp voltage formation. Rare earth metals can be employed mainly for visible light emission and chromaticity adjustment. In addition, it works somewhat for forming the ramp voltage.

  Accordingly, various metal halide lamps of small and high light output type for headlamps and projections can be obtained by appropriately selecting a plurality of metal halides of the above group.

  (4) With respect to the point that the discharge medium does not essentially contain mercury, it is preferable for mercury (Hg) not to contain any mercury (Hg) in order to reduce environmentally hazardous substances. In other words, it is acceptable even if it is contained to the extent of impurities.

(5) The tube wall load is 60 (W / cm ² ) or more because the present invention is effective for various metal halide lamps of small and high light output type such as for headlamps and projections. This is for clarity.

    According to a second aspect of the present invention, there is provided a headlamp comprising: a headlamp main body; the metal halide lamp according to the first aspect disposed in the headlamp main body; and a lighting circuit for lighting the metal halide lamp. It is characterized by that.

  In the present invention, the headlamp body refers to the remaining part of the headlamp excluding the metal halide lamp and the lighting circuit. In addition, the lighting circuit starts the metal halide lamp, and immediately after the start of lighting, continuously supplies more than twice the rated lamp power for several seconds, and then gradually reduces the rated lamp power to stable lighting. The metal halide lamp can be lit while being controlled so as to be shifted.

    According to the invention of claim 1, by satisfying A / √f ≦ 4.5, it is possible to provide a mercury-free metal halide lamp in which the occurrence of flickering of light emission is effectively suppressed.

    According to invention of Claim 2, the headlamp which has the effect of Claim 1 can be provided.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

    FIG. 1 is a side view showing the entirety of a metal halide lamp for an automobile headlamp as an embodiment for carrying out the metal halide lamp of the present invention. In this embodiment, the metal halide lamp MHL includes an arc tube IT, an insulating tube T, an outer tube OT, and a base B.

  [About the arc tube IT] The arc tube IT includes a translucent airtight container 1, a pair of electrodes 1b and 1b, a pair of external lead wires 3A and 3B, and a discharge medium.

    (Translucent Airtight Container 1) The translucent airtight container 1 is provided with an enclosure 1a that is fireproof and translucent and forms an internal space 1c with an internal volume of 0.5 cc or less. In the case of a headlamp, the internal volume is preferably 0.05 cc or less. And the internal space 1c has comprised the substantially column shape. On the other hand, the outer surface of the surrounding portion 1a of the translucent airtight container 1 has a rotating quadratic curved surface shape such as an elliptical shape or a spindle shape. Further, the wall thickness of the surrounding portion 1a is thick as a whole, the wall thickness in the central portion in the tube axis direction is the largest, and the wall thickness is gradually reduced in both end directions. As a result, the heat transfer of the translucent airtight container 1 is improved, and the temperature rise of the discharge medium adhering to the bottom surface and the side inner surface of the internal space 1c is accelerated. It works in the same way. On the other hand, the internal volume for liquid crystal projection is 0.4 cc or less. The internal space 1c has a spheroid shape. The outer surface of the surrounding portion 1a has a spherical shape or an elliptical spherical shape.

  Further, the translucent airtight container 1 is “fireproof and translucent” means that at least a light guide portion that is a portion to emit light to the outside of the surrounding portion 1a is translucent, and This means that it has at least heat resistance sufficient to withstand the normal operating temperature of the metal halide lamp MHL. Accordingly, the translucent airtight container 1 is a material having fire resistance, and any desired light guide portion can emit visible light in a desired wavelength region generated by discharge to the outside. It may be made with. For example, translucent ceramics or quartz glass can be used. In the case of a metal halide lamp for a headlamp, quartz glass having a high linear transmittance is preferable. In the latter case, a halogen-resistant or halide-resistant transparent film is formed on the inner surface of the surrounding portion 1a of the translucent airtight container 1 or the inner surface of the translucent airtight container 1 is formed as necessary. Modification is allowed.

  When the translucent airtight container 1 is made of quartz glass, a pair of sealing portions 1a1 and 1a1 can be formed at both ends of the surrounding portion 1a in the tube axis direction. The pair of sealing portions 1a1 and 1a1 seal the surrounding portion 1a, and a shaft portion of an electrode 1b described later is embedded therein, and a current is introduced from a lighting circuit (not shown) into the electrode 1b in an airtight manner. It is a means to contribute, and is integrally extended from the both ends of the surrounding part 1a. Then, in order to seal the electrode 1b and to introduce a current from the lighting circuit to the electrode 1b in an airtight manner, an appropriate hermetic sealing conduction means, preferably a sealing metal foil 2 is embedded in an airtight manner. .

  In addition, the sealing metal foil 2 is embedded in the inside of the sealing portion 1a1 in an airtight manner, and the sealing portion 1a1 cooperates to maintain the inside of the surrounding portion 1a of the translucent airtight container 1 in an airtight manner. Molybdenum (Mo) is most suitable as a material for functioning as a conductive conductor and for the case where the translucent airtight container 1 is made of quartz glass. Since molybdenum oxidizes at about 350 ° C., it is buried so that the temperature of the outer end is lower. The method for embedding the sealing metal foil 2 in the sealing portion 1a1 is not particularly limited, but for example, a reduced pressure sealing method, a pinch sealing method, or the like can be employed alone or in combination. In the case of a metal halide lamp that is used as a small lamp having an internal volume of 0.1 cc or less and in which a rare gas such as xenon (Xe) is sealed at 5 atm or more at room temperature, the latter is preferable. In the case of a metal halide lamp for liquid crystal projection, a reduced pressure sealing method is suitable.

  Further, in FIG. 1, after forming the left sealing portion 1a1, the sealing tube 1a2 is integrally extended from the outer end portion of the sealing portion 1a1 without being cut out, and extends into a base B described later. is doing.

    (Regarding a pair of electrodes 1b and 1b) The pair of electrodes 1b and 1b are sealed and opposed to the insides of both ends of the surrounding portion 1a of the translucent airtight container 1. Since the internal volume of the internal space 1c of the metal halide lamp MHL is as small as 0.5 cc or less, the distance between the electrodes is 5 mm or less, and it is 4.2 ± 0.1 mm which is standardized for headlamps. Is set. In addition, the pair of electrodes 1b and 1b is set to an appropriate value within a range where the diameter of the shaft portion is generally 0.25 to 0.5 mm, preferably 0.25 to 0.35 mm. Is good.

  Further, the pair of electrodes 1b and 1b includes a shaft portion made of a refractory metal such as tungsten (W), doped tungsten, rhenium (Re), tungsten-rhenium alloy (W-Re), and the base ends of the shaft portions. Is welded to the sealing metal foil 2 and buried in the sealing portion 1a1, the middle is loosely supported by the sealing portion 1a1 of the translucent airtight container 1, and the tip is the inner space of the translucent airtight container 1. The internal space 1c is disposed so as to face and separate from both ends of the internal space 1c.

  Furthermore, when the metal halide lamp MHL is used for a headlamp, by extending the shaft portion of the electrode 1b as it is to the tip portion without increasing its diameter, a truncated cone shape, a hemispherical shape or a semi-elliptical spherical shape is obtained. The starting point of the discharge arc is easily stabilized. In addition to this, the effect is synergistically increased by forming a small protrusion at the tip. In the present embodiment, the tip of the electrode 1b has a hemispherical shape with a curvature that is ½ of the diameter of the electrode shaft, although not shown. However, if necessary, the vicinity of the tip of the electrode 1b can be made, for example, substantially spherical or elliptical, having a diameter larger than that of the shaft. That is, the number of times the lamp blinks is very large, and a larger current flows at the time of starting than at the normal time. Therefore, if the diameter of the entire electrode 1b is increased correspondingly, the translucent airtight contact with the electrode shaft is made. Each time the constituent material of the container 1 blinks, it tends to crack due to thermal stress. Therefore, by forming a large diameter portion in the vicinity of the tip portion of the electrode 1b, the electrode 1b can be made to respond to blinking, but since the shaft portion is not large in diameter, cracks are hardly generated.

  Furthermore, the electrode 1b may be configured to operate with either alternating current or direct current. When operating with an alternating current, the pair of electrodes 1b have the same structure. When operating with direct current, the temperature of the anode generally increases greatly, so if a large diameter portion is formed in the vicinity of the tip, the heat radiation area can be increased and frequent flashing can be accommodated. On the other hand, the cathode does not necessarily have to have a large diameter portion.

    (Regarding a pair of external lead wires 3A and 3B) The pair of external lead wires 3A and 3B are welded to the other end of the sealing metal foil 2 in the sealing portions 1a1 at both ends of the translucent airtight container 1. The base end side is led out to the outside. In FIG. 1, an external lead wire 3A led rightward from the arc tube IT is folded back along an outer tube OT described later and introduced into a base B described later, and connected to one of the terminal terminals not shown. is doing. In FIG. 1, the external lead wire 3B led out from the arc tube IT to the left extends along the tube axis in the sealing tube 1a2 and is introduced into the base B to be connected to the other of the base terminals. .

    (Discharge Medium) The discharge medium contains a metal halide and a rare gas and essentially does not contain mercury. The metal halide includes a plurality of metal halides selected from the group of scandium (Sc), sodium (Na), indium (In), zinc (Zn), and rare earth metals. However, the discharge medium is not limited to a structure made of only the metal halides belonging to the above group, and it is allowed to contain a halide of a metal other than the group as an auxiliary. For example, the luminous efficiency can be further increased by adding a thallium (Tl) halide as the main light-emitting substance. Further, in addition to zinc (Zn), a metal halide for forming a lamp voltage consisting of the following groups can be added. That is, magnesium (Mg), cobalt (C), chromium (Cr), manganese (Mn), antimony (Sb), rhenium (Re), gallium (Ga), tin (Sn), iron (Fe), aluminum (Al ), Titanium (Ti), zirconium (Zr), and hafnium (Hf), by adding one or more metal halides selected from the group, the lamp voltage can be adjusted as desired. None of the above metals are expected to be metals that have high vapor pressures and do not emit light in the visible range, or that emit relatively little light, i.e., light-emitting metals that generate luminous flux, but are primarily suitable for forming lamp voltages. It is a metal.

  The rare gas acts as a starting gas and a buffer gas, and one or a plurality of kinds such as argon (Ar), krypton (Kr), and xenon (Xe) can be used. As metal halide lamps for automobile headlamps, xenon is sealed at 5 atm or more, preferably 7 to 18 atm, or sealed so that the pressure in the interior space when lighting is 50 atm or more. By doing so, when the vapor pressure of the luminescent metal immediately after the start is low, white light emission of Xe can be contributed as a luminous flux at the time of startup.

In addition, mention mercury. In the present invention, “essentially free of mercury” means that not only mercury (Hg) is not enclosed, but also there is less than 2 mg, preferably 1 mg or less of mercury per 1 cc of internal volume of the airtight container. It means that it is allowed. However, it is environmentally desirable not to enclose mercury at all. When the lamp voltage of the discharge lamp is increased to a required level with mercury vapor as in the conventional case, the short arc type may contain 20 to 40 mg per 1 cm ³ of the inner volume of the hermetic container, and moreover 50 mg or more in some cases. It can be said that the amount of mercury is substantially low.

  As the halogen constituting the halide, iodine is most suitable among the halogens in terms of reactivity, and at least the main light emitting metal is mainly encapsulated as iodide. However, if necessary, different halogen compounds such as iodide and bromide can be used in combination.

  [Insulating Tube T] The insulating tube T is made of ceramics, and the insulating tube T covers the external lead wire 3A.

  [Outer tube OT] The outer tube OT is made of quartz glass, high silicate glass, or the like, and is a means for housing at least the main part of the arc tube IT therein. Then, UV rays radiated from the arc tube IT to the outside are shielded and mechanically protected, and by touching the translucent airtight container 1 of the arc tube IT with a hand, human fingerprints and fats are attached and devitrification occurs. The light-transmitting airtight container 1 is kept warm. Further, the inside of the outer tube OT may be hermetically sealed with respect to the outside air according to the purpose, or air or an inert gas that has the same or reduced pressure as the outside air may be enclosed. Further, if necessary, it may communicate with the outside air. Further, a light shielding film can be provided on the outer surface or the inner surface of the outer tube OT.

  In the illustrated embodiment, when forming the outer tube OT, both ends of the outer tube OT are glass-welded to sealing portions extending from both ends of the translucent airtight container 1 in the tube axis direction. It can comprise so that it may support with the optical airtight container 1. FIG. The outer tube OT has an ultraviolet ray cutting performance, accommodates the arc tube IT therein, and the reduced diameter portions 4 at both ends are glass-welded to the sealing portion 1a1 of the discharge vessel IT. However, the inside is not airtight but communicates with the outside air.

  [About the base B] The base B is a means that functions to connect the metal halide lamp MHL to a lighting circuit (not shown) or to mechanically support the metal halide lamp MHL. It is standardized for use, and is constructed so that the arc tube IT and the outer tube OT are planted and supported along the central axis, and are detachably mounted on the back of the automobile headlamp. Yes.

  Next, examples will be described together with comparative example 1 and comparative example 2. Comparative Example 1 is a commercially available metal halide lamp for automotive headlamps, and Comparative Example 2 is a mercury-free lamp for automotive headlamps that does not have the configuration of the present invention.

Translucent airtight container: Internal volume of internal space 0.023cc, inner diameter 2.6mm, enclosure length 7.2mm,
Enclosure outer diameter 6.0mm
Distance between electrodes: 4.2mm
Discharge medium: Metal halide ScI ₃ -NaI-ZnI ₂ -InI-CsI, total 0.5 mg, noble gas Xe11atm
Stable lamp voltage: 44V
Lamp power when stable: 35W
Lighting frequency: 330Hz (rectangular wave AC)
Water content in translucent airtight container: 50ng (AP-MS method)
A / √f: 2.75
Flicker occurrence rate: 0%

Translucent airtight container: Internal volume of internal space 0.023cc, inner diameter 2.6mm, enclosure length 7.2mm,
Enclosure outer diameter 6.0mm
Distance between electrodes: 4.2mm
Discharge medium: Metal halide ScI ₃ -NaI-ZnI ₂ -InI-CsI, total 0.5 mg, noble gas Xe11atm
Stable lamp voltage: 44V
Lamp power when stable: 35W
Lighting frequency: 330Hz (rectangular wave AC)
Water in translucent airtight container: 20ng (AP-MS method)
A / √f: 1.1
Flicker occurrence rate: 0%

Translucent airtight container: Internal volume of inner space 0.15cc, inner diameter 6.0mm, enclosure length 8.0mm,
Enclosure outer diameter 10mm
Distance between electrodes: 5.0mm
Discharge medium: Metal halide ScI ₃ —Na—ZnI ₂ —InBr—CsI, total 3.5 mg, noble gas Xe12atm
Stable lamp voltage: 50V
Lamp power when stable: 150W
Lighting frequency: 1000Hz (rectangular wave AC)
Water content in translucent airtight container: 100ng (AP-MS method)
A / √f: 3.16
Flicker occurrence rate: 0%

[Comparative Example 1]

Translucent airtight container: Internal volume of internal space 0.023cc, inner diameter 2.6mm, enclosure length 7.0mm,
Enclosure outer diameter 6.0mm
Distance between electrodes: 4.2mm
Discharge medium: Metal halide ScI ₃ —Na—ZnI ₂ —InI—CsI, total 0.5 mg, noble gas Xe11atm
Stable lamp voltage: 44V
Lamp power when stable: 35W
Lighting frequency: 330Hz (rectangular wave AC)
Water in translucent airtight container: 90ng (AP-MS method)
A / √f: 4.95
Flicker occurrence rate: 21%

[Comparative Example 2]

Translucent airtight container: Internal volume of internal space 0.023cc, inner diameter 2.6mm, enclosure length 7.0mm,
Enclosure outer diameter 6.0mm
Distance between electrodes: 4.2mm
Discharge medium: Metal halide ScI ₃ —Na—ZnI ₂ —InI—CsI, total 0.5 mg, noble gas Xe11atm
Stable lamp voltage: 44V
Lamp power when stable: 35W
Lighting frequency: 100Hz (rectangular wave AC)
Water content in translucent airtight container: 50ng (AP-MS method)
A / √f: 5.0
Flicker occurrence rate: 25%

Next, with reference to FIGS. 2 and 3, the relationship between A / √f, the flicker occurrence rate of light emission, and the light emission efficiency including the lighting circuit will be described.

    FIG. 2 is a graph showing the relationship between A / √f and the flicker occurrence rate of light emission. In the figure, the horizontal axis represents A / √f, and the vertical axis represents the flicker occurrence rate (%). As can be seen from the figure, the higher the value of A / √f, the higher the occurrence rate of flickering, and the flickering hardly occurs when A / √f is 4.5 or less.

    FIG. 3 is a graph showing the relationship between A / √f and the luminous efficiency including the lighting circuit. In the figure, the horizontal axis represents A / √f, and the vertical axis represents relative luminous efficiency. Here, “relative light emission efficiency” indicates total light emission efficiency including a lighting circuit. As can be seen from the figure, the smaller the value of A / √f, the lower the luminous efficiency, and when A / √f is 0.016 or less, the relative luminous efficiency decreases rapidly.

    4 and 5 show an automobile headlamp as an embodiment for carrying out the lighting device of the present invention, FIG. 4 is a conceptual diagram, and FIG. 5 is a circuit diagram showing a lighting circuit. In each figure, 11 is a headlamp body, 12 is a lighting circuit, and 13 is a metal halide lamp.

  The headlamp body 11 has a container shape, and includes a reflecting mirror 11a inside, a lens 11b on the front surface, and a lamp socket not shown.

  The lighting circuit 12 has the circuit configuration shown in FIG. 5 and includes a main lighting circuit 12A and a starter 12B. The main lighting circuit 12 </ b> A is configured as described later, and can be attached to the headlamp body 11.

  The metal halide lamp 13 is a metal halide lamp shown in FIG.

  As shown in FIG. 5, the main lighting circuit 12 </ b> A includes a DC power source 21, a step-up chopper 22, an inverter 23, and a control circuit 24, and lights the metal halide lamp 13. The DC power source 21 includes a battery power source, a rectified DC power source, and the like, and has a smoothing capacitor C1 connected between DC output terminals. The step-up chopper 22 boosts the DC voltage supplied from the DC power supply 21 to a required voltage, smoothes it, and supplies the input voltage to the inverter 23 described later. Reference numeral 22a denotes a drive circuit that drives the switching element of the step-up chopper 22. The inverter 23 is a full bridge type inverter. Then, four switching elements Q1 to Q4 are bridge-connected, and a pair of switching elements Q1 and Q3 constituting the opposite two sides and a pair of switching elements Q2 and Q4 constituting the other two opposite sides are alternately switched. Then, a rectangular wave AC voltage is output between the output terminals. Reference numeral 23a denotes a drive circuit that drives the switching elements Q1 to Q4 of the inverter 23. The control circuit 24 requires the step-up chopper 22 and the inverter 23. For example, when the metal halide lamp 13 is in a cooled state, the control circuit 24 is about twice or more, for example, about 2.5 times the rated lamp power for a few seconds immediately after starting the metal halide lamp 13. Control is performed so that the lamp is lit and gradually reduced to shift to the rated lamp power during stable lighting.

  The starter 12B outputs a high voltage pulse when the metal halide lamp 13 is started, applies it to the metal halide lamp 13, and instantly starts it.

The side view which shows the whole metal halide lamp for motor vehicle headlamps as one form for implementing the metal halide lamp of this invention A graph showing the relationship between A / √f and the flicker occurrence rate of light emission Graph showing relationship between A / √f and luminous efficiency including lighting circuit The conceptual diagram which shows the motor vehicle headlamp as one form for implementing the illuminating device of this invention Circuit diagram showing lighting circuit

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Translucent airtight container, 1a ... Enclosing part, 1a1 ... Sealing part, 1a2 ... Sealing tube, 1b ... Electrode, 1c ... Internal space, 2 ... Sealing metal foil, 3A ... External lead wire, 3B ... External Lead wire, IT ... arc tube

Claims (2)

A translucent airtight container having an internal volume of 0.5 cc or less;
A pair of electrodes sealed opposite to each other with a distance between electrodes of 5 mm or less in a light-transmitting airtight container;
Contains a plurality of metal halides selected from the group of scandium (Sc), sodium (Na), indium (In), zinc (Zn) and rare earth metals, and contains noble gases and is essentially free of mercury (Hg). A discharge medium enclosed in a translucent airtight container;
The tube wall load is 60 W / cm ² or more, the moisture in the translucent airtight container is A (ng), and the lighting frequency when the rectangular wave AC voltage is applied to light is f (Hz) ), A metal halide lamp characterized by satisfying the following formula.
A / √f ≦ 4.5 A lighting device body;
The metal halide lamp according to claim 1, wherein the metal halide lamp is disposed in a lighting device body;
A lighting circuit for lighting by applying a rectangular wave AC voltage to the metal halide lamp;
An illumination device comprising:

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