JPH0690917B2 - Bulb - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to a bulb having a light-shielding film.

(Prior Art) Conventionally, a bulb such as an incandescent lamp in which a light-shielding film is formed on a part of a glass bulb has been used as a light source of a vehicle headlight, for example, and in recent years, it has become more efficient.
The use of a bulb such as a metal halide lamp with excellent vibration resistance and impact resistance has also been announced.

That is, in the case of the above headlight, if the direct light from the above-mentioned bulb arranged at the focal position of the rotary parabolic reflector is diffused and radiated forward, the driver of the oncoming vehicle is dazzled and dangerous. Therefore, a light-shielding film is usually formed on a part of the glass bulb of the tube to prevent the above danger.

However, since the light-shielding film is conventionally a coating film formed by coating, for example, aquadac or cobalt chloride on the outer surface of the glass bulb together with a binder, the light-shielding film is easily scratched and the temperature of the bulb when the bulb blinks. There is a drawback that the light-shielding film is easily peeled off due to the difference in the coefficient of thermal expansion between the two.

(Problems to be Solved by the Invention) As described above, the light-shielding film formed by coating on a part of the glass bulb has a drawback that it is easily scratched and easily deteriorated due to thermal deterioration.

Therefore, the present invention is intended to eliminate the above-mentioned drawbacks, and an object thereof is to provide a bulb having a light-shielding film which has a strong adhesion strength and is difficult to be peeled from a glass bulb.

[Structure of Invention]

(Means for Solving the Problems) In the bulb of the present invention, the light-shielding film formed on a part of the glass bulb is formed by metallic lead produced by reduction of lead oxide contained in the glass bulb. It is composed by

(Function) In the bulb of the present invention, the light-shielding film is formed by the metallic lead produced by the reduction of lead oxide contained in the glass bulb itself, so that the light-shielding film and the glass bulb have an integral structure. Therefore, the adhesion strength of the light shielding film is extremely strong,
It is possible to prevent peeling of the light-shielding film due to the difference in the coefficient of thermal expansion between the light-shielding film and the glass bulb when the bulb is scratched like a conventional coating film or when the bulb temperature changes when the tube flashes.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings. FIG. 1 is a schematic structural explanatory view of a small metal halide lamp used as a vehicle headlight light source of the present invention. In the figure, (1) is an arc tube, and an anode (2
A) and a cathode (2B) are installed oppositely, and these electrodes are connected to the lead wires (3A) and (3B), respectively, and as a starting rare gas, mercury and metal halide in the arc tube (1). Scandium iodide and sodium iodide are encapsulated. (4) is a ceramic heater, which acts as a preheating heater for facilitating the starting of the arc tube (1).
(5) is a glass bulb that hermetically surrounds the arc tube (1) and the ceramic heater (4), and is made of glass containing lead oxide, for example, borosilicate glass mainly containing silicon oxide, boron oxide, and lead oxide. , One end side of which is heated and pressed to form an airtight sealing part (5a), while the other end side surface is formed by reduction of lead oxide contained in the glass bulb (5). A light-shielding film (6) made of metallic lead is formed.

Next, a method of forming the metal halide lamp, particularly the light shielding film (6) will be described with reference to FIGS. 2 (A) and 2 (B). First, as shown in (A), one open end (5A) of a tube (5A) made of borosilicate glass containing lead oxide is
If (a) is heated in a reducing atmosphere, or as shown in the figure, until it is softened and melted in a reducing hydrogen flame (7), the open end (5Aa) becomes as shown in FIG. The lead oxide contained in the tube (5A) is sealed and reduced to form metallic lead and deposited on the surface to form a light-shielding film (6), which has a light-shielding film (6) at one end. A glass bulb for lamp (5) is obtained. According to this method,
Not only can the light-shielding film (6) be very easily formed,
Since the metallic lead forming the light-shielding film (6) forms an integral structure with the glass bulb (5), the light-shielding film (6) has an extremely strong adhesion strength and is not scratched, or is damaged from the surface of the glass bulb (5). It does not peel off.

Next, although not shown, an exhaust pipe is planted in the center of the sealed end, and the arc tube (1) and the ceramic heater (4) are inserted through the opening at the other end of the glass bulb (5), and the opening is opened. And heat-press and seal. Subsequently, after exhausting the inside of the glass bulb 5 through the exhaust pipe, nitrogen gas is filled and the exhaust pipe is closed, whereby the metal halide lamp shown in FIG. 1 is completed.

The metal halide lamp having such a structure is arranged at the focal position of the rotary parabolic reflector to form a vehicle headlamp, and the ceramic heater (4) of the lamp is energized for 1 to 3 minutes to discharge the arc tube (1). After preheating, the power supply voltage is about 15 to 30KV
If a voltage superposed with the pulse voltage is applied between both electrodes (2A) and (2B), the lamp is instantly turned on, and the light from the lamp is reflected by the reflecting mirror and radiated forward.
At this time, the direct light from the lamp, which gives the driver of the oncoming vehicle the glare, is blocked by the light shielding film to prevent the occurrence of danger.

In the above embodiment, the case where the metal halide lamp is used as the headlight light source has been described, but the present invention can be applied to the case where another tube such as an incandescent lamp is used as the light source. The present invention can be applied not only to a light source of a lamp but also to a tube having another light-shielding film used as a light source for projection or optical equipment.

〔The invention's effect〕

As described above, according to the configuration of the present invention, the light-shielding film provided in a part of the glass bulb is formed by the lead metal generated by the reduction of lead oxide contained in the glass bulb. The light-shielding film has advantages that it is hard to be scratched, does not peel off because of its extremely strong adhesion strength, and is extremely easy to form.

[Brief description of drawings]

FIG. 1 is a structural explanatory view of a metal halide lamp which is one embodiment of the bulb of the present invention, and FIGS. 2 (A) and 2 (B) are explanatory views of a method for manufacturing the same metal halide lamp. (1) …… Arc tube, (4) …… Ceramic heater, (5) …… Glass bulb, (6) …… Shading film

Claims (1)

[Claims] 1. A bulb having a light-shielding film in a part of a glass bulb, wherein the light-shielding film is formed by metallic lead produced by reduction of lead oxide contained in the glass bulb. A tube to play.