JP3386301B2 - Double bulb discharge lamp - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp used as a light source of a headlight for a vehicle such as a metal halide discharge lamp, and more particularly, to an inner bulb. The present invention relates to a discharge lamp having a double bulb structure including an outer bulb and an outer bulb. 2. Description of the Related Art FIG. 3 shows an example of the structure of a conventional double bulb discharge lamp 90. An inner bulb 91 is made of a substantially tubular hard glass such as quartz glass and has a substantially center discharge. A discharge chamber 91a is provided, and the discharge chamber 91a is formed with a distal end side lead line portion 91b and a base side lead line portion 91c provided at both ends, and the base side lead line portion 91c which is one of the lead line portions is provided at the rear. It has an appropriate length in preparation for mounting on the base 93. Here, since the hard glass such as the quartz glass has a high transmittance of ultraviolet rays, the discharge chamber 9 is discharged during discharge (lighting).
Since the ultraviolet light generated in 1a is radiated to the outside as it is and causes deterioration of, for example, resin parts constituting a headlamp, a tubular glass having an inner diameter larger than that of the inner bulb 91 and having a characteristic of shielding ultraviolet light. The member is welded at two locations, a tip side welded portion 92a and a base side welded portion 92b, to form an outer bulb 92 that covers the discharge chamber 91a, thereby preventing the above-described deterioration. [0004] A base-side lead-out portion 91c, which is one end of the inner valve 91, is embedded in the base 93 and fixed with an adhesive 94 or the like.
The wirings b and 91c are connected to the base 93 so that they can be freely attached to and detached from, for example, a headlamp lamp (not shown). [0005] However, in the above-described conventional double bulb discharge lamp 90, the mounting with the base 93 is performed by the inner bulb 91 having the smaller diameter. Therefore, in a vehicle having a small margin of durability against vibration and impact generated during traveling of the vehicle and having many opportunities to travel on a rough road, there is a problem that a break occurs at a joint portion between the base 93 and the inner valve 91. There is a need to solve this problem. According to the present invention, as a specific means for solving the above-mentioned conventional problems, a substantially tubular inner valve provided with a discharge chamber substantially at the center thereof has a substantially tubular shape. An outer bulb having an inner diameter larger than the inner bulb is attached, and the inner bulb and the outer bulb are welded at both ends of the discharge chamber to form a double bulb, and one end of the double bulb is mounted on a base. In the dual bulb discharge lamp, the outer bulb is closer to the discharge chamber than the rear end of the base-side lead wire of the inner bulb.
In addition, at the time of mounting, a base-side welding part is provided at a position inserted into the base, and a part of the outer valve is used from the base-side welding part to a position substantially corresponding to the rear end of the base-side lead-out part. A skirt portion is provided, and the welding of the inner valve and the outer valve at the one end is performed at a position where the base-side welded portion and the skirt portion are inside the base in a mounted state. The problem is solved by providing a double bulb discharge lamp characterized in that: Next, the present invention will be described in detail based on an embodiment shown in the drawings. FIG. 1 shows a first embodiment of the present invention, and the reference numeral 1 in the drawing denotes a double bulb discharge lamp. This double bulb discharge lamp 1
Is an inner bulb 2 provided with a discharge chamber 2a substantially in the center using hard glass, and a distal end side lead line portion 2b and a base side lead line portion 2c provided at both ends of the discharge chamber 2a; A tip end side welding portion 3a and a base side welding portion 3b are welded to both the lead wire portions 2b and 2c so as to cover the discharge chamber 2a using a glass member having an inner diameter larger than 2 and shielding ultraviolet rays. Outer valve 3,
It is the same as the conventional example in that it is composed of the base 4. [0008] Further, although the base-side lead wire portion 2c of the inner valve 2 is set to an appropriate length to be inserted into the base 4 at the time of mounting, as in the conventional example, According to the present invention, the base-side welded portion 3b for performing welding with the outer valve 3 is provided with the base-side lead wire portion 2c.
At the rear end. Therefore, when mounting the inner valve 2 and the outer valve 3 welded to the base 4, the base-side welded portion 3b is inserted into the base 4, and the adhesive 5 When fixing is performed by, for example, most of the area where the bonding is performed, the surface of the outer valve 3,
It becomes the inner surface of the base 4. Here, assuming that the inner valve 2 and the outer valve 3 are formed with the same thickness, and assuming that the diameter of the outer valve 3 is three times as large as the diameter of the inner valve 2, In the cross section in the direction, the area of the glass of the outer bulb 3 with respect to the inner bulb 2 is tripled,
That is, by supporting with the outer valve 3, it is possible to secure three times the strength of supporting with the inner valve 2. Simultaneously, the joint with the base 4 by the outer valve 3 also increases the bonding area. For example, under the above conditions, the bonding area increases by three times and the bonding strength also increases by three times. The possibility that the bulbs 2 and 3 are detached from the base 4 due to peeling of the adhesive can be reduced. Here, the results of a trial production and a test by the inventor for realizing the present invention will be described. First, when performing a vibration test with an acceleration of 4.5 G, a conventional method in which the inner valve 2 is joined to the base 4. In the example, breakage occurred approximately 30 minutes after the start of the test. On the other hand, in the double bulb discharge lamp 1 according to the present invention, breakage did not occur even at the end of the 4-hour test time. Is not allowed,
Improvement in vibration resistance was confirmed. In an impact test in which a drop is repeated 60 times per minute from a height of 3.2 mm, the conventional example breaks in three minutes after the start of the test, whereas the conventional example has a breakage. In the double bulb discharge lamp 1 described above, no breakage was observed even after the end of the test time of one hour, and it was confirmed that the vibration resistance and the impact resistance were improved at the same time. FIG. 2 shows a second embodiment of the present invention. In the first embodiment, the base-side welded portion 3b is provided at the rear end of the base-side lead wire 2c of the inner valve 2.
Is provided to perform welding with the outer valve 3. In the second embodiment, however, the front end of the base-side lead wire portion 2c is closer to the discharge chamber (closer to the discharge chamber), and
At the time of mounting, the base-side welded portion 3b is provided at a position inserted into the base 4. In addition, a skirt portion 3c is provided using a part of the outer valve 3 from the base-side welded portion 3b to a position substantially corresponding to the rear end of the base-side lead wire portion 2c. Therefore, when mounting is performed, the base-side welded portion 3b and the skirt portion 3c are inserted into the base 4. Therefore, the joining with the base 4 by the adhesive 5 is performed in addition to the outer surface of the outer valve 3 of the previous embodiment.
This is also performed on the inner surface and the outer surface of the skirt portion 3c and the outer surface of the inner valve 2, so that the bonding area is significantly increased, and the detachment of the valves 2, 3 from the base 4 due to the peeling of the bonding is more reliably prevented. Becomes possible. In this embodiment, it goes without saying that the vibration resistance and the shock resistance are improved as in the previous embodiment. As described above, according to the present invention, the welding of the inner valve and the outer valve at one end is performed at a position inside the base in a mounted state. By making it a double bulb discharge lamp, if the same thickness, the cross-sectional area of the glass will increase in proportion to the outer diameter. This increases the margin for vibrations and shocks generated when the vehicle travels, thereby preventing breakage accidents and the like, and is extremely effective in improving the reliability of this type of double bulb discharge lamp. [0018] In addition, the bonding with the base on the side of the outer valve increases the bonding area in proportion to the outer diameter of the base, so that the valve portion does not come off from the base. Also in this respect, an extremely excellent effect in improving the reliability of the double bulb discharge lamp is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view showing a first embodiment of a double bulb discharge lamp according to the present invention. FIG. 2 is a sectional view showing a second embodiment of the double bulb discharge lamp according to the present invention. FIG. 3 is a sectional view showing a conventional example. [Description of Signs] 1 ... Double bulb discharge lamp 2 ... Inner bulb 2a ... Discharge chamber 2b ... Leader side lead wire part 2c ... Base side lead wire part 3 ... Outer bulb 3a ... Lead side welding Portion 3b: base-side welded portion 3c: skirt portion 4: base 5: adhesive

Continuation of front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01J 61/34

Claims (1)

(57) [Claim 1] An outer bulb having a substantially tubular shape and an inner diameter larger than that of the inner bulb is attached to a substantially tubular inner valve provided with a discharge chamber substantially at the center thereof. In a double bulb discharge lamp in which an inner bulb and an outer bulb are welded at both ends of a discharge chamber to form a double bulb, and one end of the double bulb is mounted on a base, the outer bulb includes: A base-side welding portion is provided at a position closer to the discharge chamber than the rear end of the base-side lead wire portion of the inner valve, and at the time of mounting, at a position inserted into the base,
A skirt portion is provided using a part of the outer valve from the base-side welded portion to a position substantially corresponding to the rear end of the base-side drawer, and the inner valve and the outer valve at the one end are provided. Is performed at a position where the base-side welded portion and the skirt portion are inside the base in a mounted state.