• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:

    公开号:NL2007408A
    申请号:NL2007408
    申请日:2011-09-13
    公开日:2012-06-07
    发明作者:Tetsuji Hirao
    申请人:Ushio Electric Inc；
    IPC主号:
    专利说明:

    HIGH PRESSURE DISCHARGE LAMP
    This invention relates to high pressure discharge lamps for projector devices and the like, and relates specifically to high pressure discharge lamps wherein longitudinal grooves are formed in the core wire of the electrodes.
    In high pressure discharge lamps which are used as light sources for projector devices a so-called foil seal structure is employed as the sealing structure, wherein the base of the core wire of the electrode is bonded to a metal foil being embedded in the sealing portion and the electrode is energized via said metal foil.
    As, usually, the electrode core wire is comprised of tungsten while the light emitting tube consists of quartz glass, frequently the problem of damaging or a breakage of the sealing portion occurs with such a foil seal structure because of the differing coefficients of thermal expansion. This problem is even more severe with recent high pressure discharge lamps used in projector devices where a large quantity of mercury of, for example, at least 0.15 mg/mm3 is enclosed in the light emitting part and the mercury vapor pressure reaches a high pressure of at least 100 atm during the lighting.
    As a solution to this problem a technique is introduced, for example, in JP-A-2008-529252 wherein grooves are formed in the electrode core wire such that they extend in the axial direction.
    FIG. 3(A) is a schematical representation of the configuration of a lamp according to this known technique while FIG. 3(B) is an enlarged view of an electrode. As is shown in FIGs. 3(A) and 3(B), a high pressure discharge lamp 1 comprises a light emitting part 2 and sealing portions 3 at both ends thereof. Electrodes 4 are arranged in the light emitting part 2 while metal foils 5 are embedded in the sealing portions 3. A core wire 6 of the electrode 4 and an external lead 7 are bonded to said metal foil 5, and the electrode 4 is energized via the metal foil 5. At the core wire 6 of the electrode 4 a plurality of grooves 8 which extend in the axial direction is formed in the outer surface region opposite to the sealing portion 3 along the whole circumferential direction of this region.
    This known technique mentioned above attempts to avoid a breakage of the sealing portion caused by the differing coefficients of thermal expansion of the material of the electrode core wire (tungsten) and the material of the sealing portion (quartz glass) by means of rendering the surface roughness in the circumferential direction larger than the surface roughness in the longitudinal direction by providing the plurality of grooves 8 in the electrode core wire. The light emitting tube sided groove end parts are exposed to the discharge space so that no cracks occur at the sealing portion 3.
    In this regard, in the process of sealing this high pressure discharge lamp a sealing method being called 'shrink sealing' is employed because of the fact that the internal pressure is usually lower than the atmospheric pressure, wherein the pressure difference between the outside (atmosphere) and the inside (below atmospheric pressure) is utilized and the quartz glass (sealing portion) is softened and shrunk in diameter by means of a heat source such as a burner. But as in this kind of lamp a large quantity of mercury is enclosed in the light emitting part and the internal pressure increases when this mercury is vaporized because of the high temperature during the sealing, the diameter cannot be shrunk and the intended sealing is not possible. Therefore, the sealing is performed generally such that the internal pressure does not increase by arranging the light emitting tube generally such that the sealing portions are positioned vertically, and by bringing the mercury to the lower end of the sealing tube and cooling with pure water or liquid nitrogen. This sealing method is described, for example, in JP-A-2004-342497 .
    A schematic thereof is shown in FIG. 4. The lamp 1 is supported standing such that the sealing portion 3 thereof is arranged vertically. Then, an electrode mount having been assembled from the electrode 4, the metal foil 5, the external lead 7 etc. is inserted into the sealing portion 3 and heating from the outer periphery of the sealing portion 3 by means of burners 10 is performed. These burners 10 move in the vertical direction and in the circumferential direction of the sealing portion 3 and heat this sealing portion 3.
    Now, during the heat-shrinking a gap S can be formed, as is shown in FIG. 5, since the quartz glass hardly enters the corner portion at the bonding position of the rear end of the electrode core wire 6 and the metal foil 5, and if such a gap S is present, a high stress concentrates at this part and a breakage of the sealing portion 3 might be caused. To eliminate this gap S as far as possible, the position corresponding to this part is heated carefully and is heavily fired.
    Now, if axial grooves 8 are formed in the electrode core wire 6 such as mentioned above, the molten quartz glass 11 of the sealing portion 3 enters these grooves 8, as is shown in FIG. 6(A). But the molten quartz glass flows downwards in the molten state because of gravity, as is shown in FIG. 6(B). As, particularly, the region of the sealing portion-sided rear end of the grooves 8 (the upper end in the drawing) is heavily fired as was mentioned above, the viscosity of the molten glass decreases and the amount flowing downwards becomes large so that a gap 12 with regard to the grooves 8 is generated. At the sealing portion 3 the sealing is performed essentially at the region of the metal foil 5, and the position at which the grooves 8 are formed is continuously connected with the interior of the light emitting part 2. If a large gap 12 is generated in this area, the mercury in the interior of the light emitting part 2 enters this area. Mercury having once entered this gap area does not vaporize again, and eventually the mercury in the interior of the light emitting part 2 decreases and there is the problem that the desired luminance is not obtained.
    With regard to the problems of the above mentioned known technique, this invention provides a configuration for a high pressure discharge lamp with a plurality of axial grooves which have been formed in the electrode core wire, wherein it is avoided that molten quartz glass having entered said grooves at the time of sealing flows downwards and gaps are formed at the rear end part of the grooves.
    To solve the above mentioned problems the high pressure discharge lamp according to this invention is characterized in that the depth of the sealing portionsided rear end of the plurality of grooves which have been formed axially in the electrode core wire of the electrode is rendered deeper than the depth of the other parts thereof.
    Because, according to this invention, the depth of the plurality of grooves which have been formed in the electrode core wire is deep at the side of the sealing portion, quartz glass having melted during the sealing enters this deep part. In this part a resistance force against a downward flow acts so that no large gap between the glass and the groove part is formed. Therefore, there is no large decrease in the quantity of mercury in the light emitting part and the luminance does not decrease.
    The invention shall now be explained in more detail with respect to the schematic drawings in which like reference numbers denote like parts. In the drawings: FIG. 1 is a partially sectional view of an electrode core wire of a high pressure discharge lamp according to the present invention.
    FIG. 2 is an enlarged sectional view explaining the effects of the present invention.
    FIG. 3 is an overall view of a known lamp and an enlarged view of an electrode.
    FIG. 4 is an explanatory view of the sealing process of the lamp.
    FIG. 5 is an enlarged sectional view of the rear end part of the electrode core wire at a conventional sealing portion.
    FIG. 6 is an explanatory view of the conventional sealing.
    FIG. 1 is a partial sectional view of the region of the grooves 8 in the electrode core wire 6 of the high pressure discharge lamp of the present invention. As to the grooves 8 which have been formed in the axial direction of the core wire 6, the depth of the sealing portion-sided end part 8a is rendered deeper than the depth of the other part.
    The groove 8 can be formed, for example, by means of laser irradiation, and the depth of the sealing portion-sided end part 8a can be rendered deeper than the depth of the other parts of the groove by radiating the laser from the light emitting-part side of the core wire 6, moving the laser along the longitudinal direction of said core wire 6 with a constant speed, and stopping the motion of the laser at the sealing portion-sided end part so that the laser is radiated for a longer time than in the other part.
    As to exemplary numerical values, the pitch of the grooves 8 in the circumferential direction is 40 ym, the depth of the whole groove 8 is 6 ym, and the depth of the sealing portion-sided end part 8a is 9 ym.
    When a lamp having grooves 8 with such a configuration is sealed in the state shown in FIG. 4, the molten quartz glass 11 enters up to the deep groove part 8a, as is shown in FIG. 2. Therefore, a downward flow of the molten quartz glass 1 is suppressed in this deep groove part 8a because a resistance force against a downward flow becomes possible, and thus no large gap between the glass and the groove part is formed.
    Because, as was mentioned above, according to the present invention the depth of the sealing portionsided end part of the plurality of grooves which have been formed axially in the electrode core wire is rendered deeper than the depth of the other parts of the grooves, no large gap is formed between the groove and the quartz glass. Therefore there is no large decrease in the quantity of mercury in the light emitting part and the desired luminance is maintained.
    权利要求:
    Claims (2)
    [1]
    A high-pressure discharge lamp comprising a light-emitting portion made of quartz glass and having a pair of electrodes in its interior, and sealing parts formed at both ends of the light-emitting tube, wherein a metal foil is embedded in one of the sealing parts, respectively, to provide power to the electrodes, each of the electrodes comprising a core wire having grooves extending along the entire circumferential direction in an axial direction of the core wire, characterized in that the depth of the grooves varies in the axial direction such that depth in an end facing the sealing portion is deeper than the remaining portion of the groove.
    [2]
    High-pressure discharge lamp according to claim 1, characterized in that the grooves are formed by means of laser irradiation.
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    同族专利:
    公开号 | 公开日
    CN202268325U|2012-06-06|
    JP2012123918A|2012-06-28|
    JP5146858B2|2013-02-20|
    NL2007408C2|2013-06-13|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    WO2007122535A2|2006-04-21|2007-11-01|Koninklijke Philips Electronics N.V.|A method of manufacturing tungsten electrode rods|
    JP3405193B2|1998-05-07|2003-05-12|ウシオ電機株式会社|Xenon lamp|
    JP2000164172A|1998-11-30|2000-06-16|Hamamatsu Photonics Kk|Discharge tube|
    KR20100062969A|2007-08-21|2010-06-10|파나소닉 주식회사|Electrode pin for discharge lamp and method for producing the same, electrode structure, cold cathode fluorescent lamp and method for manufacturing the same, illuminating device, and liquid crystal display device|
    JP4840456B2|2009-02-06|2011-12-21|ウシオ電機株式会社|High pressure discharge lamp|
    JP2011034759A|2009-07-31|2011-02-17|Ushio Inc|High-pressure discharge lamp|EP3065899A1|2013-11-07|2016-09-14|Vesuvius Crucible Company|Nozzle for casting metal beams|
    法律状态:
    2021-05-12| MM| Lapsed because of non-payment of the annual fee|Effective date: 20201001 |
    优先权:
    申请号 | 申请日 | 专利标题
    JP2010271138A|JP5146858B2|2010-12-06|2010-12-06|High pressure discharge lamp|
    JP2010271138|2010-12-06|
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