JPH0272553A - Tubular bulb - Google Patents

Abstract

PURPOSE:To improve sputtering prevention effect by covering the external surface of a glass bulb with film consisting of fluorocarbon resin and keeping the highest temperature of the external surface at 280 deg.C-300 deg.C. CONSTITUTION:A light emitting tube 2 consisting of quartz glass, etc., is housed in an external tube 1 of a metal halide lamp, and the whole surface of the external surface of the external tube 1 is coated with film 3 consisting of fluorocarbon resin. In case of the metal halide lamp so constituted, the temperature of the external tube 1 rises up too, because the light emitting tube 2 generates heat during lighting of the lamp, but the surface temperature of the external tube 1 during the lamp light-up is made to be kept within the range from 280 deg.C to 300 deg.C. Thereby, the tensile strength of the fluorocarbon resin film at the closing days of the life increases and the mechanical strength of a glass bulb and also the sputtering preventive action improve.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a bulb in which a bulb of an incandescent light bulb, an outer bulb of a discharge lamp, etc. is coated with a fluororesin film.

(Prior Art) Tubes such as incandescent light bulbs and discharge lamps are made of glass, and if they break, glass fragments will fall, which is dangerous.

In addition, there has been an increasing trend in recent years to use metal halide lamps indoors as store lighting, but this type of lamp has an arc tube containing a highly reactive metal halide enclosed within a glass outer tube. However, in the event that the arc tube is damaged or leaks, measures are required to prevent the outer tube from bursting, and even if it does break, measures must be taken to prevent glass shards from scattering.

For this reason, it is conceivable to coat the outer surface of the bulb of the incandescent light bulb or the outer tube of the metal halide lamp with a fluororesin film.

Fluororesin coatings have better heat resistance than other resin coatings, so when coated on the outer surface of the tube, the fluororesin coating improves the mechanical strength of the tube glass and reduces breakage. Even if the tube glass breaks, it is expected to prevent glass fragments from scattering or falling.

(Problem to be solved by the invention) By the way, the lower the maximum temperature of a film made of fluororesin, the stronger its tensile strength tends to be. There is a property that there is not much difference between the two.

However, both the bulb of an incandescent light bulb and the outer bulb of a discharge lamp become hot during lighting. For this reason,
The tensile strength of the coated fluororesin film decreases.

On the other hand, if the bulb of an incandescent light bulb or the outer tube of a discharge lamp were to burst, it would most likely occur at the end of its lifespan, and most often during startup.

Therefore, even if the tensile strength decreases due to temperature rise during use, if the tensile strength at the end of the lamp's life can be increased, the initial effect of coating with the fluororesin film can be expected.

The present invention aims to provide a tube that can strengthen the tensile strength of the fluororesin coating at the time of start-up at the end of its life, reinforce the mechanical strength of the glass bulb, and improve its anti-flying effect. It is something to do.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a tube in which the outer surface of the glass bulb is coated with a coating made of fluororesin.
It is characterized in that the maximum temperature of the outer surface is maintained at 280 to 300°C.

(Function) It is certain that the tensile strength of the fluororesin coating at the end of the lamp life will be stronger if the outer surface temperature of the bulb is maintained at 280 to 300°C while the lamp is lit, compared to a temperature lower than that. Therefore, according to the present invention, the mechanical strength of the glass bulb at the end of its life is reinforced to extend the life of the lamp, and the anti-flying function is improved, thereby increasing safety.

(Example) The present invention will be described below based on an example shown in the drawings.

In the figure, reference numeral 1 indicates an outer bulb of a metal halide lamp, which is made of hard glass. An arc tube 2 made of quartz glass or the like is housed within the outer tube 1, and a predetermined amount of mercury, a metal halide, and a starting rare gas are sealed within the arc tube 2.

The outer surface of the outer tube 1 is entirely coated with a film 3 made of fluororesin.

Note that 4 indicates a cap.

In a metal halide lamp having such a configuration, the arc tube 2 generates heat during lighting, so that the temperature of the outer bulb 1 also rises.

In this case, by selecting the distance between the arc tube 2 and the outer tube 1, by adjusting the pressure of the gas sealed in the outer tube 1, or by devising the lighting equipment to which the lamp is attached, it is possible to The outer surface temperature of the tube 1 is maintained at 280-300°C.

According to such a configuration, the outer surface temperature of the outer bulb 1 is maintained at 280 to 300°C while the lamp is lit, so the tensile strength of the fluororesin coating at the end of its life is increased, and the mechanical strength of the glass bulb is increased. In addition to reinforcing the strength, the anti-fly effect is improved.

That is, as explained earlier, the lower the maximum temperature, the stronger the tensile strength of the coating 4 made of fluororesin becomes, and the lower the maximum temperature, the less the change in tensile strength between the initial stage and the end of the life. There is a property that there is no such thing.

However, the temperature of the outer bulb 1 of the metal halide lamp increases during lighting. Therefore, the tensile strength of the fluororesin coating 4 is lower than when the temperature is low.

In this case, if we compare the case where the maximum temperature during lighting is kept at 280°C or higher and the case where the maximum temperature is kept at a lower temperature, the tensile strength of the fluororesin coating 4 at the beginning of the life is lower at the lower temperature. Although it is high, the temperature is actually 280℃ at the end of its life.
It turns out that those that can be maintained above this level become stronger.

Note that if the maximum temperature during lighting exceeds 300'C, the tensile strength of the fluororesin coating 4 will be extremely reduced, and the effect of coating the fluororesin coating 4 will be impaired.

For this reason, even if the tensile strength of the fluororesin coating 4 decreases due to temperature rise during use, by keeping the outer surface temperature of the outer bulb 1 at 280 to 300°C while the lamp is lit, the lamp can be heated. The tensile strength of the fluororesin coating 4 at the end of its life can be increased, the mechanical strength of the outer tube 1 can be reinforced, and the anti-flying function can be improved.

Note that the present invention is not limited to the above embodiments.

That is, in the above embodiments, the case where the present invention is applied to the outer bulb of a metal halide lamp has been described, but the present invention can also be applied to the outer bulb of other discharge lamps, the bulbs of incandescent lamps, thermal lamps, and the like.

[Effects of the Invention] As explained above, according to the present invention, the tensile strength of the fluororesin coating at the end of its life is increased, so the mechanical strength of the outer bulb is reinforced at the end of its life, resulting in a longer lamp life. At the same time, the anti-fly function is improved and safety is increased.

[Brief explanation of the drawing]

FIG. 1 shows one embodiment of the present invention, and is a front view showing the entire metal halide lamp. 1... Outer tube, 2... Arc tube, 3... Fluororesin coating. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Claims] A tube bulb characterized in that the outer surface of the glass bulb is coated with a film made of fluororesin, and the maximum temperature of the outer surface is 280 to 300°C.