JP2011034756A - High-pressure discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mercury-free high-pressure discharge lamp enclosed with Xe that lowers the starting voltage and having startability improving effect by using a means for reducing the breakdown voltage. <P>SOLUTION: The high-pressure discharge lamp is equipped with a translucent ceramic airtight vessel 1, including an enclosure 1a and a pair of small diameter tube parts 1b, 1b extending in the tube axial direction in communication with both ends of the enclosure; first and second electrodes 2A, 2B the base ends of which are inserted in the small diameter tube part and the tips of which face the inside of the enclosure and separately face each other; an arc tube IT, including an ionized medium enclosed in the translucent ceramic airtight vessel, while containing a metal halide and xenon of 1 atm or more at 25°C and essentially containing no mercury; an outer tube OT containing the arc tube inside and including a base; and a proximity conductor TW, the base end of which is conductively connected to the first electrode, the intermediate part of which extends along the outer surface of the enclosure and in contact with it, and the terminal of which goes round the outer surface of the small-diameter tubular part at the position facing the second electrode. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a mercury-free high pressure discharge lamp essentially free of mercury.

A high-pressure discharge lamp in which a metal halide, such as zinc halide, which emits less visible light and is effective for forming a lamp voltage is replaced with mercury and made mercury-free is known (for example, Patent Document 1). reference.). Patent Document 1 describes an example in which the distance between the electrodes is 4.2 mm, xenon is 1 atm, ScI _{3 is} 0.14 mg, NaI is 0.86 mg, FeI _{2 is} 1 mg, the input power is 35 W, and the restart voltage is 7 kV. (Paragraphs 0215-0230). Also, for direct current lighting with an anode, a cathode and an auxiliary electrode, the distance between the electrodes is 40 mm, the rare gas is 280 Torr, the ScI _{3 is} 3 mg, the NaI is 15 mg, and the second halide (3 examples of AlI ₃ , ZnI ₂ , and GaI ₃ ) An example is described where the restart voltage is 0.8-1.0 kV with an input power of 400 W enclosing a 20 mg discharge medium (paragraphs 0347-0369). In any of the above examples, the translucent airtight container is considered to be made of quartz glass with reference to FIGS. 6 and 16.

  On the other hand, in the existing mercury-containing ceramic metal halide lamp, most of the starting gas is sealed with Ar 0.1 to 0.5 atm. On the other hand, in a metal halide lamp using a mercury-free translucent ceramic hermetic vessel, by enclosing Xe instead of Ar, the lamp voltage that tends to be lowered by not using mercury and the voltage decreases accordingly. Luminous efficiency can be increased to a practical lamp voltage and lamp efficiency.

JP-A-11-238488 (paragraphs 0216-0230, 0370-0380)

  Since Ar shows a clearly lower dielectric breakdown voltage compared to Xe at the same pressure, a small current discharge such as glow discharge can be started with a lower starting pulse voltage. However, in the case of Ar, it is difficult to shift from a minute current discharge to an arc discharge as compared with Xe.

  The selection of Ar and Xe as the starting gas is determined by the balance between the breakdown voltage and the ease of transition to arc discharge, and is set according to the type of lamp.

  The inventor of the present invention uses a means for reducing the dielectric breakdown voltage in a mercury-free high-pressure discharge lamp encapsulating Xe, so that the startability improvement effect that cannot be obtained with an existing mercury-containing Ar-enclosed high-pressure discharge lamp is obtained. It was found that it can be obtained.

  It is an object of the present invention to provide a mercury-free high-pressure discharge lamp in which Xe is sealed, which uses a means for reducing the dielectric breakdown voltage to reduce the starting voltage and is excellent in the startability improving effect.

  In order to solve the above problems, a high-pressure discharge lamp according to the present invention includes a surrounding portion having a discharge space therein and a pair of small-diameter cylindrical portions that communicate with both ends of the surrounding portion and extend in the tube axis direction. An optical ceramic hermetic container, including first and second electrodes whose proximal ends are inserted into a small-diameter cylindrical portion and whose distal ends are opposed to each other facing the surrounding portion, and a metal halide and xenon at 1 atm or higher at 25 ° C. An arc tube having an ionization medium enclosed in a light-transmitting ceramic hermetic vessel essentially free of mercury; an outer tube containing the arc tube and having a base; A conductive conductor connected to the first electrode, an intermediate portion extending along and in contact with the outer surface of the surrounding portion, and a terminal conductor orbiting the outer surface of the small-diameter cylindrical portion at a position facing the second electrode; Characterized by comprising: There.

  In the mercury-free high-pressure discharge lamp enclosing Xe, the base end is conductively connected to the first electrode, the intermediate portion is in contact with the outer surface of the enclosure of the translucent ceramic hermetic container, and the end is the second end. The proximity conductor that circulates on the outer surface of the small-diameter cylindrical portion facing the electrode of the electrode makes it easier for dielectric breakdown to occur inside the translucent ceramic hermetic container, and the high-pressure discharge lamp transitions to arc discharge immediately after the dielectric breakdown. As a result, the starting voltage is lowered and an excellent effect of improving the startability is obtained.

  In addition, by including an ultraviolet enhancer, it is possible to provide a mercury-free high-pressure discharge lamp encapsulating Xe that further reduces the starting voltage and provides an excellent starting performance improvement effect.

It is a front view of the metal halide lamp concerning one form for carrying out the high-pressure discharge lamp of the present invention. It is an expanded sectional side view which similarly shows an arc tube. It is the principal part diagonal side view which similarly shows the proximity | contact state with respect to the arc tube of a proximity conductor, and a modification. It is a graph which similarly shows a starting voltage with that of a comparative example.

  Embodiments of the present invention will be described below.

  One mode for carrying out the high-pressure discharge lamp of the present invention shown in FIGS. 1 to 3 is as follows. That is, as shown in FIG. 1, the high-pressure discharge lamp of this embodiment is a metal halide lamp with a rated lamp power of 150 W that can be applied to general lighting applications, and includes an arc tube IT, an outer tube OT, a proximity conductor TW, and an ultraviolet enhancer UVE. It has. In the figure, SG is a protective glass tube, SF is an arc tube support member, G is a getter, and B is a base.

  As shown in FIG. 2, the arc tube IT includes a translucent ceramic hermetic container 1, first and second electrodes 2A, 2B, a pair of current introduction conductors 3, 3, a pair of sealing materials 4, 4 and It consists of an ionization medium.

  The translucent ceramic hermetic container 1 is made of translucent ceramics, preferably translucent polycrystalline alumina ceramics. And the surrounding part 1a and a pair of small diameter cylindrical parts 1b and 1b are provided. Preferably, the surrounding portion 1a and the pair of small-diameter cylindrical portions 1b and 1b are connected via a continuous curved surface and are integrally formed. The surrounding portion 1a has a discharge space 1c formed therein, and has, for example, a bowl shape as shown in FIG. 2, and includes an intermediate cylindrical portion and a pair of hemispherical portions continuous at both ends thereof. The small-diameter cylindrical portion 1b has an elongated pipe shape, and the tip communicates with the central portion of the hemispherical portion of the surrounding portion 1a.

  The first and second electrodes 2 </ b> A and 2 </ b> B are made of a rod-like body of doped tungsten. It is welded and the middle part is inserted inside the small-diameter cylindrical part 1b while forming a capillary having a slight gap around it. In addition, an electrode mount subcoil 2b formed by winding a thin wire such as tungsten is disposed around the shaft portion 2a located inside the small-diameter cylindrical portion 1b of the first and second electrodes 2A and 2B. .

  The current introduction conductor 3 includes a sealing portion 3a and a halogen-resistant portion 3b connected in series. The sealing portion 3a is made of a two-obed rod-like body, seals the translucent airtight container 1 in cooperation with a sealing material 4 to be described later, and has a base end of the translucent ceramics airtight container 1. Exposed outside. The halogen-resistant portion 3b is made of a molybdenum rod-like body, and its base end is butt welded to the tip of the sealing portion 3a and inserted into the small-diameter cylindrical portion 1b of the translucent ceramic hermetic container 1. Moreover, the base end of the electrode 2 is welded to the front-end | tip part. The diameter of the halogen-resistant portion 3b is the same as that of the shaft portions of the first and second electrodes 2A and 2b, and the electrode mount subcoil 2a extends to the halogen-resistant portion 3b.

  As long as the sealing material 4 seals the translucent ceramic hermetic container 1 in cooperation with the small-diameter cylindrical portion 1b and the current introduction conductor 3, the material and the sealing mode are not particularly limited. For example, the sealing material 4 may be formed as a result of sealing the translucent ceramic hermetic container 1 by fusing a small diameter cylindrical portion 1b or a ceramic material similar thereto. However, in this embodiment, the sealing material 4 is made of a frit glass, that is, a melted and solidified body of a ceramic compound, enters the small diameter cylindrical portion 1b, and seals the current introduction conductor 3 positioned in the small diameter cylindrical portion 1b. The gap between the adhesive portion 3a and the inner surface of the small diameter cylindrical portion 1b is filled, and the surface of the adhesive portion 3a is surrounded so as not to be exposed in the translucent ceramic hermetic container 1.

  The ionization medium consists of a metal halide and xenon.

  The metal halide includes at least a metal halide that mainly contributes to light emission. In the present invention, the light emitting metal is not limited to a specific metal. However, in this embodiment, a rare earth metal belonging to a lanthanoid, for example, thulium (Tm) and holmium (Ho) at least one halide together with a metal halide such as sodium (Na) as a metal halide mainly contributing to light emission. Can be encapsulated. Thulium (Tm) is a particularly preferred luminescent metal because it has high luminous efficiency and has the effect of increasing the lamp voltage. Holmium (Ho) has the above effect next to thulium. In addition to the above, when thallium (Tl) is enclosed, if the inner volume of the translucent ceramic hermetic container 1 is regulated to less than 0.8 mg / cc, the phenomenon of suppressing blue light emission is effectively reduced. be able to.

If desired, a metal halide for forming a lamp voltage, such as ZnI _2, can be added. However, mercury is essentially not included.

  The rare gas is composed of a xenon-based rare gas of 1 atm or more when the ambient temperature is 25 ° C. Note that the effect of the present invention is exhibited when xenon is at least 25 atm. The pressure is preferably 10 atm or less, and more preferably 5 atm or less. If the enclosed pressure of xenon is 10 atm or less, the starting voltage is low, and if it is 5 atm or less, the starting voltage can be 5 kV or less.

  The outer tube OT may be made of any appropriate material, and can be formed using, for example, hard glass. As shown in FIG. 1, the arc tube IT and at least the proximity conductor TW are disposed inside in a manner described later. Further, preferably, members such as the ultraviolet enhancer UVE, the protective glass tube SG, the arc tube support member SF, and the getter G are housed in predetermined positions, and the inside is in a vacuum.

  Further, in this embodiment, the outer tube OT is provided with a flare stem 5 sealed at a neck portion located at the lower portion in FIG. The flare stem 5 is provided with a pair of internal lead-in wires 6a and 6b protruding in an airtight manner into the outer tube OT.

  The arc tube IT is disposed at a substantially central portion of the outer tube OT along the central axis inside the outer tube OT, and the current introduction conductor 3 on the upper portion thereof is welded to a connection piece 8 to be described later to form an arc tube support member. While being supported by SF, it is connected to the internal lead-in wire 6a via the arc tube support member SF. Further, the arc tube IT is supported by the lower current introduction conductor 3 being welded to the connection conductor 7 via the connection piece 9, and the internal introduction line 6 b via the connection conductor 7. Connected to.

  The proximal conductor TW is electrically connected to the first electrode 2A shown in FIG. 2 because its proximal end is welded to the upper current introducing conductor 3 of the arc tube IT in FIG. 1 and FIG. Connecting. As shown in FIG. 3, the middle extends along the outer surface of the surrounding portion 1a and extends toward the second electrode in contact with the outer surface of the surrounding portion 1a. The contact with the outer surface of the surrounding portion 1a may be the whole or a part of the portion facing the surrounding portion 1a. However, even if the proximity conductor TW is positioned in the vicinity of the outer surface of the surrounding portion 1a, if it is not in contact with the surrounding portion 1a, dielectric breakdown is less likely to occur.

  The proximity conductor TW can be formed using a conductive and heat-resistant metal such as tantalum (Ta), molybdenum (Mo), and tungsten (W), or an alloy of two or more thereof.

  Furthermore, the aspect of extension of the proximity conductor TW along the surrounding portion 1a is such that when the proximity conductor TW is viewed from the side, the proximity conductor TW extends linearly along the tube axis direction. Preferably it is visible. This is due to the following reason. That is, the mercury-free high-pressure discharge lamp is characterized in that a discharge path is easily formed along the inner surface of the surrounding portion 1a during dielectric breakdown. At this time, if the adjacent conductor TW extends in the above-described manner, a discharge path is easily formed along the adjacent conductor TW. As a result, the dielectric breakdown in the translucent ceramic hermetic container 1 is further promoted.

  Further, in the present embodiment, the proximity conductor TW is formed around the boundary portion with the surrounding portion 1a of the upper small diameter cylindrical portion 1b in FIG. 1 to form the ring r1, and then the outer conductor TW is formed on the outer surface of the surrounding portion 1a. Extends in the manner described above. Then, as shown in FIG. 1 and FIG. 3A, the ring r2 is formed by rotating the outer surface a plurality of times, for example, 5 turns, at the position facing the second electrode 2B of the lower small diameter cylindrical portion 1b as shown in FIGS. The translucent ceramic hermetic container 1 is fixed to the outer surface. The ring r2 may be formed of a ribbon-shaped metal fitting having a width of 5 mm and a thickness of 0.5 mm, for example, as in the modification of FIG. The ring r1 can also be formed with a ribbon-like metal fitting as desired.

  Therefore, in FIG. 1, since the potential of the upper electrode (not shown) is applied to the adjacent conductor TW through the translucent airtight container 1 in the vicinity of the lower electrode, the ring portion r2 and the lower electrode 2B are applied. A large potential gradient is formed between the two. Therefore, when a high starting voltage of 5 kV or less is applied between the pair of electrodes 2A and 2B, the start of the high pressure discharge lamp is promoted.

  Then, when a starting high voltage is applied between the first and second electrodes 2A, 2B of the arc tube IT at the time of starting, the second electrode 2B and the portion of the adjacent conductor TW that directly faces this (ring) Since the potential gradient with respect to r2) is increased, a minute discharge occurs. Next, a micro discharge extends to the first electrode 2A along a portion inward of the adjacent conductor TW on the inner surface of the surrounding portion 1a to form a discharge path, and dielectric breakdown is performed.

  In the ultraviolet enhancer UVE, the tip of one conductor l1 is sealed in a small and ultraviolet transmissive envelope to form an internal electrode. The base end of one conductor l1 is supported by welding to the arc tube support member SF. The other conductor l2 that holds a ribbon-like external electrode (not shown) in close contact with the outer peripheral surface of the ultraviolet ray transmissive envelope is welded to the support frame 8 of the arc tube support member SF described later. Therefore, the ultraviolet enhancer UVE is connected in parallel to the arc tube IT. A UV-radiating rare gas or the like is sealed in the UV-transmitting envelope.

  Then, when a high starting voltage is applied between the pair of electrodes 2A and 2B prior to the start of the high pressure discharge lamp, the ultraviolet enhancer UVE starts glow discharge first, and the generated ultraviolet light is emitted from the arc tube IT. Irradiate near the lower electrode. As a result, electrons are emitted from the electrode 2B or the like by a photoelectric effect, and this acts as initial electrons, which excites the ionization medium in the arc tube IT and makes it easy to start. As a result, the starting voltage is clearly lower than when the ultraviolet enhancer UVE is not provided.

  The protective glass tube SG is made of a quartz glass cylinder, and surrounds the arc tube IT in a separated state, thereby suppressing the scattering of fragments when the arc tube IT is ruptured. And it is supported by the arc tube support member SF described later.

  The arc tube support member SF is formed by bending a stainless steel rod into an elongated deformed U-shape, and is connected to the internal lead-in wire 6a, and a connection piece 8 is bridged on the open end side of the U-shape.

  The getter G is a performance getter supported at the upper part in the figure of the arc tube support member SF.

  The base B is a screw-type base and is attached to the lower part of the outer tube OT in FIG. 1 and connected to the pair of internal lead-in wires 6a and 6b.

  Example 1 is a configuration in which the metal halide lamp shown in FIG. 1 does not include an ultraviolet enhancer.

Translucent ceramic hermetic container: Polycrystalline alumina ceramics integrated molding, maximum outer diameter 11.4mm, wall thickness 0.8mm, total length 60mm, internal volume 1.5cc
Pair of electrodes: doped tungsten, distance between electrodes 13mm
Ionization medium: TmI ₃ -NaI = 9 mg, ZnI ₂ = 2.5 mg, Xe = 3 atm Proximity conductor: Mo wire, diameter 0.1 mm
Outer tube atmosphere: Vacuum

Example 2 has the same configuration as Example 1 except that the metal halide lamp shown in FIG. 1 includes an ultraviolet enhancer.

FIG. 4 is a graph showing start test results of two lamp configuration examples according to an embodiment of the present invention. The horizontal axis represents Example 1 and Example 2, and the vertical axis represents the starting voltage. In Example 1, the proximity conductor facilitated the dielectric breakdown inside the translucent ceramic hermetic container, so that the starting voltage was reduced to 4.5 kV or less. In Example 2, an ultraviolet enhancer was added to the configuration of Example 1. As a result, the starting voltage is about 1 kV or less lower than that of the first embodiment on average.

  DESCRIPTION OF SYMBOLS 1 ... Translucent airtight container, 1a ... Enclosing part, 1b ... Small diameter cylinder part, 1c ... Discharge space, 2A ... 1st electrode, 2B ... 2nd electrode, 2a ... Electrode axial part, 2b ... Electrode mount subcoil 3 ... Current introduction conductor, 3a ... Sealing part, 3b ... Halogen-resistant part, 4 ... Sealing material, 5 ... Stem, B ... Base, IT ... Arc tube, OT ... Outer tube, SF ... Arc tube support member , SG ... protective glass, TW ... proximity conductor, UVE ... ultraviolet enhancer

Claims (3)

A translucent ceramic hermetic container having an enclosure portion having a discharge space therein and a pair of small-diameter cylindrical portions communicating with both ends of the enclosure portion and extending in the tube axis direction, the proximal end is inserted into the small-diameter cylindrical portion, and the distal end is inserted First and second electrodes facing and facing the enclosure, and a metal halide and xenon of 1 atm or higher at 25 ° C., and essentially free of mercury, are contained in a light-transmitting ceramic hermetic container. An arc tube with an encapsulated ionization medium;
An outer tube containing an arc tube inside and having a base;
Proximity where the proximal end is conductively connected to the first electrode, the middle extends along and in contact with the outer surface of the surrounding portion, and the terminal end circulates around the outer surface of the small-diameter cylindrical portion at a position facing the second electrode With conductors;
A high-pressure discharge lamp comprising:   The high-pressure discharge lamp according to claim 1, further comprising an ultraviolet enhancer.   3. The high-pressure discharge lamp according to claim 1, wherein a discharge path is generated along the inner surface of the surrounding portion facing the adjacent conductor at the time of dielectric breakdown inside the translucent ceramic hermetic container.

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