JPH0220753Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a cold cathode discharge lamp in which the cap-shaped electrode does not come into contact with the bulb wall.

[Technical background of the invention]

BACKGROUND ART Conventionally, cold cathode discharge lamps have been widely used for instrument panel lighting and the like due to their short start-up time.
Such discharge lamps need to be compact and as bright as possible. For this reason,
The electrode is configured as a cap-shaped electrode with a large surface area to obtain a large current, and to avoid blackening near the electrode and abnormal temperature rise of the electrode itself, and this electrode is fixed to the tip of the inner conductor by means such as welding. It has been done.

[Problems with background technology]

Because the large-diameter cap-shaped electrode is accommodated within the small-diameter bulb, the gap between the electrode and the inner surface of the bulb is narrow.
There was a risk that the electrode could come into contact with the inner surface of the bulb due to eccentricity or inclination of the stem or bending of the inner conductor. In addition, when the electrode shakes due to vibration or impact, it collides with the inner surface of the bulb and scrapes off the phosphor.
It may make abnormal noise or cause abnormal discharge.
In severe cases, it may cause the electrode to fall off.

[Purpose of invention]

This invention eliminates the risk of the electrodes coming into contact with the inner surface of the bulb even if the stem is slightly eccentric or tilted, or the inner conductor is slightly bent, and the electrodes do not collide with the inner surface of the bulb due to vibrations or collisions. The object of the present invention is to provide a cold cathode discharge lamp that is free from the risk of damage.

[Summary of the idea]

By making the tip of the cap-shaped electrode smaller in diameter than the base, the electrode surface area is not reduced and the electrode does not come into contact with the inner surface of the bulb even if it is tilted.

[Example of idea]

The details of the invention will be explained by means of illustrated embodiments. 1 is a straight tube type bulb, 2 is a phosphor coating formed on the inner surface of the bulb 1, 3, 3 is a flare stem that closes both end surfaces of the bulb 1, and 4, 4 is a tube that flows from the stems 3, 3 into the bulb 1. Introduced inner conductor,
Reference numerals 5 and 5 designate cap-shaped electrodes welded to the ends of the inner conducting wires 4, 4, and 6, 6 represent outer conducting wires led out from the stems 3, 3. The bulb 1 is filled with a small amount of mercury and a discharge gas such as argon or neon.

As shown in FIGS. 2 and 3, the electrode 5 has a main body 51 formed into a hollow truncated conical shape with an open proximal end surface, and a pair of slits extending from the proximal edge 52 to the middle part of the side wall 53. 54, 54, and an electrode hole 56 is formed in the center of the top plate 55, and the edge of this hole 56 is bent inward to form a support edge 57, and zircon or the like is accommodated in this support edge 57. A ring getter 58 is attached. Then, as shown in FIGS. 4 and 5, the base of the electrode 5 is placed on the top of the stem 3, the top end of the stem 3 is positioned near the tip of the slit 54, and the inner conductor 4 is placed on the side. It is bent toward the side, pulled out from the slit 54, and fixed to the outer surface of the side wall 53 by means such as electric welding.

To assemble this discharge lamp, first, the inner conductors 4, 4 of the flare stem 3 are bent laterally and cut to an appropriate length, and the ring getter 58 is
Take the electrode 5 equipped with a
Welded to the outer surface of the side wall 53 of. Then, the stem 3 mounted in this manner is sealed to the end face of the bulb 1 and assembled into a discharge lamp.

In assembling such a discharge lamp, the electrode 5 tilts due to the following reasons.

(A) When the electrode 5 is installed at an angle to the inner conductor 4.

(B) When the inner conductor 4 is led out at an angle to the axis of the stem 3.

(C) When the inner conductor 4 is bent or bent.

(D) When stem 3 is sealed at an angle to the axis (X-X) of valve 1.

For these reasons, the electrode 5 may be tilted. For example, as shown in FIG. 6, it is assumed that the stem 3 is tilted and that the inner conducting wire 4 is led out from the stem 3 at a tilt. In this case, the electrode 5 is inclined with respect to the bulb axis (X-X) and approaches the inner surface of the bulb 1 as shown in the figure. However, in this embodiment, the diameter of the tip end of the electrode 5 is smaller than the diameter of the base end, so even if the electrode 5 is tilted, the tip end has a sufficient gap from the inner surface of the bulb 1, and is protected against vibrations and shocks. Tsute electrode 5
Even if it vibrates, it does not come into contact with the inner surface of the bulb 1, so the phosphor coating 2 will not be scraped off, nor will it cause abnormal noise or abnormal discharge. Note that the same applies to cases due to other displacement causes.

Furthermore, in this embodiment, the side wall 53 of the electrode 5
Since a slit 54 is formed in the slit 54 and the inner conductor 4 is led out from the slit 54, the base of the electrode 5 can be placed on the top of the stem 3, and the influence of the inclination of the stem 3 and the outer conductor 4 can be reduced accordingly. In particular, when the electrode 5 is welded at an angle with respect to the inner conductor 4, the apex of the slit 54 becomes the fulcrum of the inclination, which has the advantage of reducing the amount of displacement. be. Furthermore, in this embodiment, since the electrode 5 is placed on the top of the stem 3, there is an additional effect that the discharge length can be made longer compared to the bulb length.

In the present invention, as shown in FIGS. 7 and 8, the electrode 5 is made of a plurality of cylinders 5a with different diameters,
A similar effect can be obtained by configuring the layer 5b in a step-like structure in which the diameter becomes smaller as it approaches the tip. The point is that the diameter of the tip end of the electrode 5 should be smaller than that of the base end. Thus, the electrode cross section is not limited to a circular shape.

In addition, in the present invention, the stem is not limited to a flared shape, and it is sufficient that the inner conductive wire is introduced into the valve from the end face of the valve.

[Effect of idea]

In the cold cathode discharge lamp of the present invention, the tip of the cap-shaped electrode is made smaller in diameter than the base, so even if there is some dimensional error or assembly error, the electrode will not come into contact with the inner surface of the bulb, and it will not cause vibrations or shocks. There is no risk of the electrode colliding with the inner surface of the bulb.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of an embodiment of the cold cathode discharge lamp of the present invention, Fig. 2 is a longitudinal cross-sectional view of the electrode, Fig. 3 is a longitudinal cross-sectional view of the electrode from another direction, and Fig. 4 is the same. FIG. 5 is a cross-sectional view of the electrode mounted on the stem, FIG. 5 is a plan view of the similarly mounted electrode, FIG. 6 is an explanatory diagram showing that the electrode of the discharge lamp of the above embodiment hardly comes into contact with the bulb, and FIG. 7 is a diagram of the electrode mounted on the stem. Another example side view,
FIG. 8 is also a plan view. 1...Valve, 3...Stem, 4...Inner conductor,
5...electrode, 53...side wall, 54...slit.

Claims (1)

[Claims for Utility Model Registration] (1) A tubular valve, an inner conductor introduced from the end face of the valve, and a cap-shaped electrode attached to the tip of the inner conductor, the tip of which has a smaller diameter than the base end. A cold cathode discharge lamp characterized by comprising: (2) The electrode has a slit formed from the proximal edge to the center of the side wall, and the inner conductive wire passes through the slit from within the electrode, leads out to the outer surface of the side wall, and is fixed to the outer surface. A cold cathode discharge lamp according to claim 1 of the utility model registration claim. (3) Utility model registration claim 2, characterized in that the end face of the valve is closed with a flared stem to introduce an inner conductor, and the head of this stem is inserted into the electrode. Cold cathode discharge lamp as described in section.