JPS6145350B2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to fluorescent lamps.

FIG. 1 shows a conventional fluorescent lamp. That is, in this fluorescent lamp, the inner surface of a glass tube 1 is coated with a phosphor 2, a discharge space 3 inside the glass tube is filled with a predetermined amount of mercury and an inert gas, and a stem 5 is embedded in the tube end. A mount in which a filament 6 serving as a lamp electrode is attached to the inside of a tube of a lead wire 4 is sealed, and the other end of the lead wire 4 is connected to a base pin 7. The light emitting principle of this fluorescent lamp is that mercury atoms are excited by accelerated electrons in the tube, and when the mercury atoms in the excited state return to the stable ground state of mercury, they emit ultraviolet light.
This ultraviolet radiation (mainly 234 nm) is irradiated onto the phosphor, exciting the phosphor and emitting visible light according to Stokes' law.

However, when this type of fluorescent lamp is lit for a long time, electrode materials, electron radioactive substances, mercury, etc. adhere to the glass tube wall near the tube end, causing a so-called blackening phenomenon at the glass tube end. The drawback was that the light emission decreased. At the same time, the phosphor deteriorates due to the emitted ultraviolet light (mainly 185 nm), and the luminescence of the entire lamp tube decreases, resulting in a decrease in the total luminous flux relative to the lamp input power, that is, the lamp efficiency. In addition, the length of the blackened tube end is small relative to the overall length of the lamp, and the decrease in luminous flux due to deterioration of the phosphor is gradual, so consumers and users can continue to use the lamp without noticing even if the efficiency of the lamp decreases. It's wasting power.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a fluorescent lamp in which lamp life can be automatically detected.

A first embodiment of the invention is shown in FIGS. 2 to 4. That is, in this fluorescent lamp, the inner surface of a glass tube 1 is coated with a phosphor 2, a discharge space 3 inside the glass tube is filled with a predetermined amount of mercury and an inert gas, and the tube end is embedded in a stem 5. The mount 8 is made up of a filament 6 attached to the inside of the tube of the lead wire 4, and as shown in FIG.
As shown in FIG. 5, the lead wire 4 connected to the filament 6 and the electrodes 10, 11 are connected to the lamp cutoff circuit 13, and the output end 14 of the cutoff circuit 13 is connected to the cap. Connected to pin 7. Lamp cutoff circuit 13 during this lifespan
connects a resistor R between the anode and gate of a bidirectional switch element (e.g. triax) S,
A lead wire 4 is connected to the anode, and both electrodes 10 and 11 of the life detection element 12 are connected to the gate and cathode, respectively, and the cathode is used as the output end 14 of the cutoff circuit.

FIG. 6 shows a lighting circuit using this fluorescent lamp. In the figure, E is the power supply, H is the ballast, and G is the glow starter. When the lamp is lit by the circuit opening operation of the glow starter G, a discharge current flows between the filaments 6 via the cutoff circuit 13. When the tube wall blackening has not progressed much during the lamp life period from the beginning of lighting, the insulator 9 of the life detection element 12 contains the electrode material, electron radioactive material, mercury, and their oxides as shown in FIG. It is attached. In this case, since the insulation between the electrodes 10 and 11 is maintained, the bidirectional switch element S continues to conduct, and the lamp continues to operate normally. However, as the lamp is turned on for a long period of time, the tube wall gradually darkens, and at the same time, the luminous flux decreases due to deterioration of the phosphor. Substances, electron radioactive substances, mercury, and their oxides will adhere without any gaps. For example, if the length of the insulator 9 is 7 mm and the height is 7 mm using a 40W fluorescent lamp, this can be achieved in 10,000 hours. Of course, this time can be increased by increasing the length of the insulator. At this point, the life detection element 12
Since the insulation properties of the bidirectional switch element S are reduced and the gate and cathode of the bidirectional switch element S are short-circuited, the bidirectional switch element S is cut off. At this time, if the resistance value of the resistor R is made sufficiently large, the lamp current will decrease, and the lamp will no longer be able to maintain its lighting state and will go out. In this way, automatic detection of lifespan becomes possible. Therefore, it is possible to prevent a disadvantageous situation in which a consumer unknowingly uses a lamp whose efficiency has decreased at the end of its lamp life and wastes power.

Note that the cutoff circuit may be provided within the lamp tube or may be provided outside the lamp tube. Further, the life detection element may be provided not only at one end of the lamp but also at both ends of the lamp tube. Furthermore, it is not always necessary to turn off the lamp at the end of its life; instead, an external circuit that utilizes changes in the resistance of the insulator 8 to generate a sound to indicate the end of the lamp's life, turn on the bulb, or display text is required. It is also possible to notify the end of the lamp life without turning off the lamp. It is also possible to notify the user of the lamp life after the lamp is turned off. Furthermore, the fluorescent lamp is not limited to a glow start type, but may be a rapid start type.

A second embodiment of the invention is shown in FIG. That is, in this fluorescent lamp, the life detection element 15 is connected to a ring 18 consisting of a conductive part 16 and an insulating part 17.
The conductive part 16 is used as an electrode, and the rest is the same as the first embodiment. In this case, since the ring 18 surrounds the periphery of the filament, the blackening substance cannot reach the tube wall, and tube wall blackening does not occur. Therefore, the lamp does not darken during its life, and when the phosphor deteriorates due to long-term lighting and the luminous flux decreases, the lamp automatically turns off.

As described above, the fluorescent lamp of the present invention has the effect that the end of the life can be automatically detected because the life detection element having the counter electrode provided on the surface of the insulator is provided inside the lamp tube.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway side view of a conventional fluorescent lamp, Fig. 2 is a partially cutaway side view of a first embodiment of the present invention, Fig. 3 is a cross-sectional view thereof, and Fig. 4 is a life detection element. 5 is a cut-off circuit diagram, FIG. 6 is a lighting circuit diagram, FIGS. 7 and 8 are enlarged front views of the life detection element in a changing state, and FIG. 9 is an enlarged front view of the second embodiment. FIG. 3 is a perspective view of main parts. 1... Glass tube (lamp tube), 6... Filament, 12, 15... Life detection element.

Claims (1)

[Scope of Claims] 1. A lamp tube comprising a lamp tube, lamp electrodes provided at both ends within the lamp tube, and a pair of electrodes provided in the vicinity of the lamp electrodes in the lamp tube and facing each other on the surface of an insulator. A fluorescent lamp equipped with a lamp life detection element. 2. The fluorescent lamp according to claim 1, wherein the lamp life detection element has a ring shape surrounding the lamp electrode.