JP2007323986A - Discharge lamp and discharge lamp device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp capable of preventing abnormal discharge and whitening of a reflector; and a discharge lamp device. <P>SOLUTION: In this discharge lamp, one end of an arc tube LB is held to a socket 6; and the socket 6 has a flange 61 on the front end side, and a cylindrical wall 64 formed protrusively in the front end direction from the rear end in the inside for inserting the one end of the arc tube LB therein. When it is assumed that the thickness of the cylindrical wall 64 of the socket 6, the area of the cylindrical wall 64 on the front end side, and the area of the flange 61 having a diameter not larger than 26 mm are d, S<SB>1</SB>and S<SB>2</SB>, relationships of d≥2.0 (mm), and S<SB>1</SB>+S<SB>2</SB>≤300 mm<SP>2</SP>are satisfied. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a discharge lamp and a discharge lamp device used for automobile headlamps and the like.

  As an example of a discharge lamp used for a headlight of an automobile, for example, there is an invention of JP-T-2004-534363 (hereinafter referred to as Patent Document 1). As described in this document, the discharge lamp is configured by inserting and holding one end of an arc tube in a socket in which a space is formed.

  And when using a discharge lamp like patent document 1 for a headlamp etc., as shown in FIG. 6 of Unexamined-Japanese-Patent No. 2003-297226 (henceforth patent document 2), it combines with a reflector. Used.

JP-T-2004-534363 JP 2003-297226 A

  In order to start lighting such a discharge lamp, a high-pressure pulse of about 20 kV is applied at the start. If this high voltage pulse is continuously applied every time it is lit, a discharge may occur at a location that is not originally between the electrodes where the discharge is performed. (Hereinafter, this phenomenon is called abnormal discharge.) When this abnormal discharge occurs, in the worst case, the lamp does not light up.

  On the other hand, when the discharge lamp is incorporated in the reflector and lit, a phenomenon occurs in which part of the reflecting surface of the reflector is whitened and clouded. This problem is also mentioned in Japanese Patent Application Laid-Open No. 2001-23427.

  Therefore, as a result of conducting various tests by the present inventors, it has been found that the phenomenon of abnormal discharge and reflector whitening can be suppressed without using special materials by reviewing the design of the socket. It came to do.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide a discharge lamp and a discharge lamp device that can suppress the occurrence of abnormal discharge and whitening of a reflector.

In order to achieve the above object, the discharge lamp of the present invention is a discharge lamp in which one end of an arc tube is held by a socket, the socket being formed with a flange on the front end side and extending from the rear end toward the front end inside. And a cylindrical wall into which one end of the arc tube is inserted, the thickness of the cylindrical wall of the socket is d, the area of the cylindrical wall on the front end side is S ₁ , and the area of the flange within a diameter of 26 mm is S _2. In this case, d ≧ 2.0 mm and S ₁ + S ₂ ≦ 300 mm ² are satisfied.

  According to the present invention, abnormal discharge and whitening of the reflector can be suppressed.

  Hereinafter, a discharge lamp according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall view showing an embodiment of a discharge lamp according to the present invention.

  The discharge lamp DL has an arc tube LB in which discharge is performed. The arc tube LB has a double tube structure, and an inner tube 1 is formed inside. The inner tube 1 has an elongated shape, and an elliptical discharge portion 11 is formed at the approximate center of the tube axis. Plate-shaped sealing portions 12a and 12b are formed at both ends of the discharge portion 11, and cylindrical non-sealing portions 13a and 13b are formed at both ends thereof. For such an inner tube 1, it is possible to select a material having heat resistance that can sufficiently withstand high temperatures during lighting and translucency that allows the generated light to pass through with as little loss as possible. Specifically, quartz glass, ceramics such as translucent alumina, and the like can be used.

  Inside the discharge part 11, the center is substantially cylindrical, and tapered discharge spaces 14 are formed at both ends thereof. The volume of the discharge space 14 is desirably 10 μl to 40 μl for a discharge lamp used in an automobile.

  The discharge space 14 is filled with a discharge medium made of a metal halide and a rare gas. As the metal halide, halides of sodium, scandium, zinc, and indium are enclosed. For the halide bonded to these metals, it is most preferable to select iodine having low reactivity among halides. However, the halide to be bonded is not limited to iodine, and bromine, chlorine, or a combination of a plurality of halides may be used.

  As the rare gas, xenon which has high luminous efficiency immediately after starting and mainly acts as a starting gas is enclosed. The pressure of xenon is preferably 5 atm or more, more preferably 10 to 15 atm at normal temperature (25 ° C.). In addition to xenon, neon, argon, krypton, or the like may be used as the rare gas, or a combination thereof may be used.

  Here, the discharge space 14 essentially does not contain mercury. This “essentially mercury-free” means an amount equivalent to no mercury at all or almost not enclosed even when compared with a conventional mercury-containing discharge lamp, for example, less than 2 mg per ml, Preferably, even if an amount of mercury of 1 mg or less is present, it is acceptable.

  Inside the sealing portions 12a and 12b, metal foils 2a and 2b made of, for example, molybdenum are sealed so that their flat surfaces are parallel to the planes of the sealing portions 12a and 12b.

  Electrodes 3a and 3b made of a material obtained by doping tungsten with about 2.0% by weight of thorium oxide are connected to ends of the metal foils 2a and 2b on the discharge part 11 side by laser welding or the like. The shape of the electrodes 3a and 3b is a stepped shape in which the distal end side has a larger diameter than the proximal end side. The distal end side of the large diameter is arranged so that the distal ends thereof are opposed to each other while maintaining a predetermined inter-electrode distance in the discharge space 14. Here, the “predetermined interelectrode distance” is preferably about 3.5 to 4.5 mm for a vehicle headlamp. In addition, it is the specification by which the coil was wound by the base end side.

  One end of a lead wire 4a, 4b made of molybdenum is connected to the end of the metal foil 2a, 2b opposite to the discharge part 11 by laser welding or the like. The other ends of the lead wires 4a and 4b extend to the outside of the sealing portions 12a and 12b along the tube axis.

  Further, on the outside of the inner tube 1, at least one oxide selected from titanium, cerium, aluminum, potassium, barium, etc. is added to quartz glass, thereby blocking ultraviolet rays and providing high translucency. A cylindrical outer tube 5 is provided so as to cover most of the inner tube 1 in the tube axis direction. The connection between the inner tube 1 and the outer tube 5 is performed by welding both ends of the outer tube 5 to the outer peripheral surfaces of the non-sealing portions 13a and 13b of the inner tube 1. As a result, welded portions in which the inner tube 1 and the outer tube 5 are mixed are formed at both ends of the arc tube LB.

  A socket 6 made of PPS resin (polyphenylene sulfide resin), which is a glass fiber reinforced plastic material having excellent heat resistance and moldability, is connected to the non-sealing portion 13a side of the arc tube LB configured as described above. . These connections are made by attaching a ring-shaped metal band 71 attached to the outer peripheral surface of the outer tube 5 to four metal tongues 72 (two in FIG. 1) formed on the opening side of the socket 6. (Illustrated). In addition, in order to strengthen those connections further, the contact point of the metal band 71 and the tongue piece 72 may be laser-welded.

  Here, the structure of the socket 6 will be described in more detail with reference to the explanatory view of the socket of FIG. (A) is the figure which looked at the socket from the front end part direction, (b) is the figure which looked at the cross section of X-X 'from the arrow direction.

  The socket 6 is formed with a flange 61 on the front end side. A space 62 is formed inside the socket 6. The front end side of the space 62 has a large opening at the center of the flange 61, and four recesses 63 for mounting the tongue pieces 72 are formed at equal intervals along the circumference of the opening. Part of the space 62 penetrates to the rear end side of the socket 6, and a bottom terminal 81 formed at the bottom of the socket 6 is located at the outlet. Therefore, when the socket 6 and the arc tube LB are connected, the lead wire 4a protrudes to the bottom and can be electrically connected to the bottom terminal 81 by laser welding or the like.

  Furthermore, a cylindrical wall 64 is formed in the space 62 so as to protrude from the rear end side toward the front end. The cylindrical wall 64 has a thickness d of 2.0 mm or more and a height h of 8.0 mm or more in order to maintain a sufficient withstand voltage. Inside the cylindrical wall 64, a space that is slightly larger than the diameter of the welded portion of the arc tube LB is formed. For example, in the present embodiment, the diameter of the welded portion of the arc tube LB is 6 mm, and the internal space of the cylindrical wall 64 is 8 mm in diameter. Therefore, even if the end of the arc tube LB is inserted into the cylindrical wall 64, an interval of about 1 mm is maintained.

  In addition, a space 65 whose front end side is open is formed in a part of the flange 61. The space 65 is composed of two spaces having different sizes. The small space penetrates to the rear end side of the socket 6, and the side terminal formed on the outer surface of the socket 6 is located at the outlet. For this reason, when the support wire 91 having one end connected to the lead wire 4a is inserted into the space 65, the other end protrudes and can be electrically connected to the side terminal 82 by laser welding or the like. Note that an insulating sleeve 92 made of ceramic covering the portion of the support wire 91 that is substantially parallel to the tube axis of the arc tube LB is inserted into the large space 65.

  One specification of the dimensions, materials, etc. of the discharge lamp DL of the present embodiment is shown below. The following tests are based on this specification unless otherwise specified.

Discharge vessel 1: made of quartz glass, discharge space 14 volume = 26 μl, inner diameter = 2.6 mm, outer diameter = 6.2 mm, maximum axial length = 7.8 mm
Discharge medium: total 0.7 mg of sodium iodide, scandium iodide, zinc iodide, indium bromide, metal halide, xenon = 11 atm
Electrodes 3a and 3b: Tungsten oxide doped tungsten material, tip diameter = 0.38 mm, base end diameter = 0.30 mm, actual distance between electrodes = 4.4 mm
Socket 6: made of PPS resin, flange 61 inner diameter r ₂₁ = 20 mm, outer diameter r ₂₂ = 32 mm, cylindrical wall 64 inner diameter r ₁₁ = 8 mm, outer diameter r ₁₂ = 12 mm, thickness d = 2 mm, height h: 9mm
75 W at start-up, 35 W at stable lighting, horizontal lighting FIG. 3 is a diagram showing the results when the test was performed with the thickness d of the cylindrical wall changed. This test was conducted under lighting conditions in which a 20 kV pulse was applied to the lamp while the power was turned on and off repeatedly. The lamp was taken out every 5000 times, and a pulse was applied 5 times. However, the case where abnormal discharge occurs is determined as x, and the case where it does not occur is determined as o.

  From the results, there is a relationship between the thickness d of the cylindrical wall 64 and the occurrence of abnormal discharge. The thinner the thickness d, the easier the abnormal discharge occurs with a smaller number of pulse applications, and the thicker the thickness d, the more abnormal discharge occurs. It is difficult to understand that when the wall thickness d of the cylindrical wall 64 is 2.0 mm or more, no pulse leak occurs even if it is turned on and off more than 20000 times. In addition, if power ON-OFF is performed 20000 times, it is equivalent to having lighted for about 2000 hours or more.

  The cause of abnormal discharge in the above test is considered as follows.

  The cylindrical wall 64 has a function of preventing a short circuit between the lead wire 4 a and the support wire 91 when a high voltage pulse is applied to the bottom terminal 81 and the side terminal 82. For example, in the case of a PPS resin, it is said that a dielectric breakdown voltage of about 10 kV is improved if the thickness is 1.0 mm. However, when a high-pressure pulse is repeatedly applied to the lamp, the cylindrical wall 64 is affected by heat and ultraviolet rays, and the resin at that portion deteriorates. As the battery deteriorates, the withstand voltage decreases. For this reason, even if a sufficient wall thickness is secured in the initial stage, it is likely that pulses will leak through the deteriorated part during the lifetime, and abnormal discharge has occurred between the lead wire 4a and the support wire 91. It is done.

  That is, from the viewpoint of preventing abnormal discharge, the thicker the cylindrical wall 64 is, the more desirable it is, and it is desirable that the wall thickness d is 2.0 mm or more that can maintain a practical life time from the test results.

FIG. 4 shows a discharge lamp apparatus in which a discharge lamp is mounted on a reflector, and the test was performed by changing the sum S ₁ + S ₂ of the area S ₁ of the cylindrical wall on the front end side and the area S _{2 of} the flange exposed from the hole. It is a figure which shows the result of time. This test is a continuous lighting with a power of 35W. The determination of the result is that when the vicinity of the Y portion of the reflector shown in FIG. 5 is clouded and whitened after 1000 hours, and the light distribution is affected, x is whitened, but the light distribution is affected. A case where there is no problem in use, such as a degree, is judged as △, and a case where it is not whitened is judged as ◯. Note that the area of the flange 6 forming the recess 63 and the space 66 is calculated by S ₁ = π (r ₁₂ ² −r ₁₁ ² ) / 4 and S ₂ = π (R ² −r ₂₁ ² ) / 4. Does not contain. Here, the hole diameter R of the hole of the reflector in this test is 26 mm. The reflector having a hole diameter R of 26 mm is the size of a reflector for automobile headlamps that is currently most commonly used.

The results, sum S _{1 +} S ₂ of the area of the flange exposed from the area with the holes on the front end side of the cylindrical wall is related to the whitening of the reflector, the more whitening is less likely to occur that the value, if the 300 mm ² or less Although a little whitening is seen, there is no problem with the use, and it can be seen that there is no problem if it is 290 mm ² or less.

The relationship between the sum S ₁ + S ₂ of the area of the cylindrical wall on the front end side and the area of the flange exposed from the hole and whitening is considered as follows.

  When the discharge lamp DL is examined in detail after the test, when the reflector is whitened, it is exposed in the reflector through the hole when it is attached to the portion indicated by the oblique lines in FIG. 6, that is, the reflector. It was confirmed that the flange 61 and the front end side of the cylindrical wall 64 of the socket 6 were strongly clouded. This means that even the arc tube LB entirely surrounded by UV-cut glass cannot completely block the ultraviolet rays generated in the discharge part 11, and the ultraviolet rays transmitted through the arc tube LB are not connected to the axis of the arc tube LB. This means that the surface on the front end side of the socket 6 having a substantially vertical relationship is particularly easily irradiated. Therefore, the front end surface of the flange 61 and the cylindrical wall 64 deteriorates due to the influence of ultraviolet rays and heat during lighting of the arc tube LB, and the gas immediately above the lamp by the gas containing sulfur generated from the resin at the time of deterioration. It is considered that the Y portion of the reflector is whitened.

From the above consideration, the present inventors considered that it is sufficient to reduce the amount of gas generated due to resin deterioration in order to prevent whitening of the reflector, and the front end side of the flange 61 and the cylindrical wall 64 in which deterioration has been confirmed. I have come up with a configuration that reduces the area that reacts with ultraviolet rays by reducing the area of the area. However, are in a proportional relationship to each other is the area S ₁ of the front end side of the cylindrical wall 64 and the thickness d of the wall, reducing the area S ₁ thickness d becomes thinner, it becomes impossible to suppress abnormal discharge . Therefore, it is important to keep the sum S ₁ + S ₂ of the area S ₁ of the cylindrical wall 64 and the area S ₂ of the flange 61 exposed from the hole in a suitable range while ensuring the minimum thickness d.

From the above, the sum S ₁ + S ₂ of the area S ₁ of the cylindrical wall 64 on the front end side and the area S _{2 of the} flange 61 exposed from the hole of the reflector is 300 mm ² or more, and the thickness d of the cylindrical wall 64 If this is 2.0 mm or more, both of the problems can be solved. Incidentally, Within this range, in order to increase the reliability of abnormal discharge, to increase the thickness d of the cylindrical wall 64, instead of the area S ₁ is increased, adopting the structure to reduce the area S ₂ You can also.

Therefore, in the present embodiment, when the thickness of the cylindrical wall 64 of the socket 6 is d, the area of the cylindrical wall 64 on the front end side is S ₁ , and the area of the flange 61 within a diameter of 26 mm is S ₂ , d ≧ 2. Since the discharge lamp DL satisfies the relationship of 0 (mm) and S ₁ + S ₂ ≦ 300 mm ² , abnormal discharge and whitening of the reflector occur for a long time when used in combination with a widely used reflector. Can be prevented.

(Second Embodiment)
FIG. 7 shows a discharge lamp device according to the second embodiment of the present invention. About each part of this 2nd Embodiment, about each part of 2nd Embodiment and the following embodiments, the same part as each part of the flat fluorescent lamp of 1st Embodiment is shown with the same code | symbol, Description is omitted.

  The discharge lamp device includes a discharge lamp DL, a reflector RE, a shade SH, a lens LE, and an igniter IG.

  The discharge lamp DL is configured as described in detail in the first embodiment, and includes the arc tube LB and the socket 6.

  The reflector RE has a reflecting portion 101 that is formed in a curved surface. One end of the reflecting portion 101 is opened to extract light. A fixed portion 102 is continuously formed at the other end, and a hole 103 is formed through the reflective portion 101 and the fixed portion 102. Therefore, when the discharge lamp DL is fixed to the reflector RE, the arc tube LB is inserted into the hole portion 103, and the discharge portion 11 is disposed at a desired position.

  FIG. 8 is a diagram when the reflector to which the socket is fixed is viewed from the opening side. As can be seen from the drawing, most of the socket 6 is exposed from the hole 103. Specifically, a part of the flange 61, the cylindrical wall 64, and the bottom side of the space 62 are located from the front.

  The shade SH is a metal formed in an L shape, and one end is fixed to the bottom surface of the reflector RE. When the discharge lamp DL is fixed to the reflector RE, the other end is arranged at such a position as to cover a part on the tip side. Thereby, a dangerous glare with respect to an oncoming vehicle is interrupted | blocked in a motor vehicle headlamp.

  The lens LE is a convex lens and is disposed on the opening side of the reflector RE. And the light made into the substantially parallel light by the reflector RE is condensed to form a desired light distribution.

  The igniter IG is connected to the bottom side of the socket 6 of the discharge lamp DL and electrically connected to the bottom terminal 81 and the side terminal 82. The igniter IG applies a high-pressure pulse of about 20 kV to the discharge lamp DL at the time of start-up, causing dielectric breakdown between the electrodes, and then arc discharge is performed by ballast (not shown).

In this discharge lamp apparatus, even if the hole diameter R of the hole 103 of the reflector RE is not 26 mm, which is generally used, the flange S exposed from the area S ₁ of the cylindrical wall 64 on the front end side and the hole 103. When the area S _{3 of} 61 satisfies the relationship of S ₁ + S ₃ ≦ 300 mm ² , it was confirmed that whitening of the reflector RE can be suppressed as in the result of FIG.

Therefore, in this embodiment, when the thickness of the cylindrical wall 64 of the socket 6 is d, the area of the cylindrical wall on the front end side is S ₁ , and the area of the flange 61 exposed from the hole 103 is S ₃ , d Since the discharge lamp device satisfies the relationship of ≧ 2.0 (mm) and S ₁ + S ₃ ≦ 300 mm ² , abnormal discharge and whitening of the reflector can be prevented for a long time.

1 is an overall view showing an embodiment of a discharge lamp according to a first embodiment of the present invention. Explanatory drawing of a socket. The figure which shows the result when changing the thickness d of a cylindrical wall, and testing. In the discharge lamp apparatus in which the lamp is mounted on the reflector, the result when the test was performed by changing the sum S ₁ + S ₂ of the area S ₁ of the cylindrical wall on the front end side and the area S _{2 of} the flange exposed from the hole is shown. FIG. The figure which attached the lamp | ramp to the reflector. The figure which shows the socket after a test. The whole figure which shows embodiment of the discharge lamp apparatus of 2nd Embodiment by this invention. The figure which looked at the state which attached the socket to the reflector from the opening side.

Explanation of symbols

DL discharge lamp 1 inner tube 11 discharge part 12a, 12b sealing part 13a, 13b non-sealing part 14 discharge space 2a, 2b metal foil 3a, 3b electrode 4a, 4b lead wire 5 outer tube 6 socket 61 flange 64 cylindrical wall 71 Metal band 72 Tongue piece 81 Bottom terminal 82 Side terminal 91 Support wire 92 Insulating sleeve RE Reflector 103 Hole

Claims (2)

In a discharge lamp in which one end of the arc tube is held in a socket,
The socket has a flange on the front end side and a cylindrical wall that extends from the rear end toward the front end inside, and has one end of the arc tube inserted therein. The thickness of the cylindrical wall of the socket is d, A discharge lamp characterized by satisfying a relationship of d ≧ 2.0 mm and S ₁ + S ₂ ≦ 300 mm ² where S _{1 is} an area of the cylindrical wall and S ₂ is an area of the flange having a diameter of 26 mm or less. In a discharge lamp device comprising: a discharge lamp in which one end of an arc tube is held by a socket; and a reflector having a hole and holding the discharge lamp in a state where the arc tube is inserted into the hole,
The socket has a flange on the front end side and a cylindrical wall that extends from the rear end toward the front end inside, and has one end of the arc tube inserted therein. The thickness of the cylindrical wall of the socket is d, A discharge lamp characterized by satisfying a relationship of d ≧ 2.0 mm and S ₁ + S ₃ ≦ 300 mm ² where S _{1 is} an area of the cylindrical wall and S ₃ is an area of the flange exposed from the hole. apparatus.

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