JPH03187150A - Fluorescent lamp - Google Patents

Abstract

PURPOSE:To prevent the breaking of a glass tube at the end of the lifetime of a fluorescent lamp by stretching a pair of filament electrodes of a single- ended metal fluorescent lamp whose glass tube forming a discharge route is folded ino a U-shape, in parallel on the surface along the discharge route, and by specifying the tube diameter and the lamp current density of the lamp in a certain range. CONSTITUTION:A pair of filament electrodes 1 of a compact type fluorescent lamp, which is a thin-tube and high-load tipe fluorescent lamp whose tube diameter is not more than 20mm, and lamp current density is not less than 1.2X10<-3>A/mm<2>, and whose glass tube 2 forming a discharge route is folded in a U-shape into a single-ended metal 3 structure, are supported horizontally to the lighting derection of the fluorescent lamp. A free end is not connected to a glass wall, even when the electrode 1 is melted at the one end of a support line 10, while is hung down due to the heat at the other end. The arc heat of the electrode is not directly transmitted to the glass tube thereby. The breaking of the glass at the end of the lifetime of the lamp can thus be prevented.

Description

[Detailed description of the invention] [Industrial field of application] The present invention is applicable to lamps with a tube diameter of 20 mm or less and a lamp current density of 1.2.
It is concerned with small-diameter, high-load fluorescent lamps of X10 A/mm" or more, and is particularly used in the support structure of the filament electrode.

[Conventional technology]

As shown in Figs. 3 and 4, a sheath tube high-load type fluorescent lamp with a tube diameter of 20 mm or less and a lamp current density of 1.2 x 10 A/mm" or more is used. The glass tube 2 has a U-shaped discharge path. A so-called compact fluorescent lamp having a structure with three folded single caps is well known.

The pair of filament electrodes 1' are stretched parallel to each other on a support wire 10. Due to its shape, this type of fluorescent lamp is used so that the surface along the U-shaped discharge path is a horizontal surface. Based on this usage condition, the pair of filament electrodes 1' are stretched approximately vertically. 30 is a bottle with a cap 3.

[rRH that the invention seeks to solve]

The conventional fluorescent lamp described above has a problem in that when it is used with a high frequency inverter, the glass tube 2 of the lamp breaks at the electrode 1' portion at the end of the lamp's life.

The results of investigating this phenomenon were as follows. The oxide is consumed on one side of the lamp electrode l°, resulting in a half-wave discharge state. Then, the electrode 1' is heated abnormally and one end of the electrode 1' and the support wire 10 is fused. Even in this state, the discharge is maintained, so that the electrode 1 bends due to heat and hangs downward under its own weight from the connection between the electrode 1' and the support wire 10, which are not fused. In this kind of thin tube in which the distance between the electrode l' and the glass tube 2 is short, the hanging end of the electrode 1' comes into contact with the glass tube 2.

Then, the arc heat of the electrode 1' is directly transmitted to the glass tube 2, causing the glass tube 2 to break at that portion.

It is unclear why the electrode 1' becomes abnormally heated when half-wave discharge occurs during high-frequency lighting, but it is presumed as follows. When the oxide is consumed, the number of working hours of the electrode 1' increases significantly, resulting in a significant increase in the cathode drop voltage. However, at high frequencies, the ions in front of the electrode 1' are not completely annihilated, so that field radiation due to space charges remains. Therefore, it cannot be ignored
The @ style continues. Due to the increased cathode fall voltage and the current that does not decrease sufficiently, the electrode 1' is heated to a greater extent than in the normal state.

An object of the present invention is to prevent glass tube breakage during the life of this type of fluorescent lamp.

[t! Means to solve the problem]

In order to achieve the above object, the filament electrode is supported horizontally with respect to the lighting direction of the fluorescent lamp.

[Effect]

By supporting the filament electrode horizontally, even if the electrode fuses at one end with the support wire and hangs down due to heat at the other end, the free end will not touch the glass wall, so the arc heat of the electrode will not reach the glass tube. It is not transmitted directly and can prevent damage to the glass.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2. The parts numbers other than the filament electrode 1 are the same as in the conventional one. The glass tube 2 is bent into a U-shape, and a pair of filament electrodes 1 are located at the ends of the tube. This pair of filament electrodes 1 are stretched parallel to the plane along the U-shaped discharge article. As shown in the explanatory diagram of FIG. 5, consider a case where one end of the filament electrode 1 connected to the support wire 10 is fused and hangs down due to its own weight. glass tube 2
If the inner diameter is r and the distance between the support lines 10 and 10 is b, then the condition that the free end of the electrode 1 does not come into contact with the inner glass wall is expressed by the following formula.

b'+ (b/2)"≦(r/2)" In other words, if b≦0.45r, there will be no contact.Actually, the filament electrode l is not bent at a right angle, so if it is about boo, 6r, it is acceptable. can. This range is within the range in which this type of lamp can be manufactured.

〔Effect of the invention〕

As described above, according to the present invention, since the filament electrode is stretched horizontally with respect to the normal lighting direction for this type of fluorescent lamp, even if the electrode melts and sags at the end of the support wire during the life of the lamp, the free end of the electrode comes into contact with the glass tube. There are very few things. Therefore, the phenomenon that the glass tube is damaged can be prevented.

[Brief explanation of drawings]

Fig. 1 is a sectional view of the electrode part of a fluorescent lamp showing an embodiment of the present invention, Fig. 2 is a side view thereof, Fig. 3 is a sectional view of the electrode part of a fluorescent lamp showing a conventional example, and Fig. 4 is a side view thereof. , FIG. 5 is an explanatory diagram of the present invention. 1 is a filament electrode, 2 is a glass tube, ]O is a support line.

Claims (1)

[Claims] 1. Lamp current density is 1.2×1 when tube diameter is 20mm or less
0^-^3A/mm^2 or more, in a single-cap fluorescent lamp in which the glass tube forming the discharge path is bent into a U-shape, a pair of filament electrodes both have a surface along the U-shaped discharge path. A fluorescent lamp characterized by being stretched parallel to the