JPH0557692B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a fluorescent lamp, and more particularly to a compact fluorescent lamp used for illuminating a display section of a portable electronic device such as a portable computer.

[Conventional technology]

Conventionally, this type of compact fluorescent lamp was usually manufactured as a cold cathode, and the reason for this is that, for example, a compact fluorescent lamp with a tube diameter of about φ8 was not manufactured like a typical household fluorescent lamp. If a hot cathode is used, the internal volume will be smaller, so
If the discharge power of the lamp is high, the temperature of the tube wall will rise above the appropriate temperature, resulting in a decrease in efficiency. In order to solve this problem, the discharge power of the lamp must be reduced.
This can be solved by keeping the voltage to about 3W, but when realizing this with a lighting circuit like the one shown in Figure 5, the electrode must be made smaller in order to maintain the filament temperature of the electrode above 1200 Kelvin. This is because the amount of emitter applied to the electrode is also reduced, resulting in a shortened lifespan.

[Problem that the idea aims to solve]

However, when the above-mentioned fluorescent lamp is formed with a cold cathode, the efficiency decreases, and at the same power and the same life span, the luminous flux is only about half that of a hot cathode, resulting in a dark fluorescent lamp. The lifespan of the hot cathode is less than half that of the hot cathode. Particularly in portable electronic devices and the like, the tube length of the fluorescent lamp is determined by the overall shape of the device, so in fluorescent lamps where the brightness obtained is determined by the tube length, cold cathodes do not provide the necessary illuminance. This created the problem that it was impossible to do so, and the solution to this problem had become an issue.

[Means to solve the problem]

The present invention provides a concrete means for solving the conventional problems described above, in which each electrode of the fluorescent lamp is
The hot cathode is coated with 0.1 to 1.5 mg of emitter, and a power of 1/2 or less of the discharge power is applied to each of these electrodes, independent of the discharge power of the lamp. By providing a compact fluorescent lamp having these characteristics, the above-mentioned conventional problems can be solved as a compact fluorescent lamp having sufficient brightness and a sufficient lifespan.

【Example】

Next, the present invention will be explained in detail based on an embodiment shown in the drawings. The reference numeral 1 in FIG. 1 is a compact fluorescent lamp according to the present invention. This compact fluorescent lamp 1 has a tube diameter of about φ8 mm and has low power consumption, and is used, for example, in portable electronic equipment. It is similar to the conventional example in that it is used for illuminating a display, but instead of the cold cathode used in conventional devices of this type, a hot cathode 1a, for example, is made of a double-coil tungsten filament. 1b, and these hot cathodes 1a and 1b contain, for example, Ba, Sr,
Emitter 2 such as Ca is applied. Further, as shown in the figure, by providing power sources Ea and Eb for generating heat for the hot cathodes 1a and 1b separately from a high voltage power source Ec for discharging, the discharge power can be reduced.
It is possible to suppress the heat generation power of the hot cathode to about 3W and determine the power generated by the hot cathode without being restricted by this discharge power. The following Figures 2 to 4 show the results of experiments conducted by the inventor to realize the present invention, and the curve WE in Figure 2 shows the curve WE of the emitter 2 with respect to one of the hot cathodes 1a and 1b. This shows the amount that can be coated, and as the filament power of the hot cathode 1a (or 1b) increases, that is, the size of the filament increases, the amount that can be coated by the emitter 2 also increases. . The curve EL in FIG. 3 expresses the relationship between the amount of coating of the emitter 2 and the life of the small fluorescent lamp 1, where tube diameter =
These are experimental results obtained under certain conditions of φ7.75 mm and discharge current = 20 mA. For example, if the amount of emitter 2 applied is 0.5 mg or more, the life of this small fluorescent lamp 1 is guaranteed to be 15,000 hours. It was found from FIG. 2 that in order to ensure a coating amount of 0.5 mg or more of the emitter 2, the filament power of the hot cathode 1a (or 1b) was required to be approximately 0.9 W. The curve WL in FIG. 4 is obtained by calculating the relationship between the filament power of the hot cathode 1a (or 1b) and the life of the lamp 1 from FIGS. 2 and 3. The relationship between the lamp 1 and its life under discharge current conditions can be directly read. By adopting the above experimental results, the compact fluorescent lamp 1 can be constructed with a tungsten filament hot cathode 1a,
1b, it is possible to improve the light output to approximately twice or more than that of a cold cathode fluorescent lamp, and at the same time make it comparable in terms of life. Incidentally, from the results of the above experiment, the hot cathode 1a,
By increasing the filament power of filament 1b, the coating amount of emitter 2 will also increase, and a further increase in life can be expected. Since the improvement in light output is approximately twice that of a cold cathode fluorescent lamp, the range in which the increase in power consumption due to the hot cathodes 1a and 1b exceeds the improvement in light output is outside the scope of the present invention. The invention excludes this part and sets the total heat generation power of each electrode to 1/2 or less of the lamp output (the total power of the heat generation power of both electrodes and the discharge power), i.e. The power for heating each electrode is limited to 1/2 or less of the power for discharging.

【Effect of the invention】

As explained above, according to the present invention, the discharging power of the fluorescent lamp and the heating power of the electrodes are made independent, and the total heating power of each electrode is reduced to 1/2 or less of the lamp output. Yes and 0.1~
By creating a compact fluorescent lamp with a hot cathode coated with 1.5mg of emitter, we have been able to provide a compact fluorescent lamp that is approximately twice as bright as a cold cathode fluorescent lamp, even with the same tube diameter and tube length, and has a long service life. This can be done without any shortening, and this type of compact fluorescent lamp has an excellent effect on improving the performance of portable equipment in which it is used. In addition, since the discharging power and the electrode heating power are applied independently, the discharging power can be changed while the electrode filament temperature is always maintained above a certain temperature, making dimming possible. becomes.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing an embodiment of a compact fluorescent lamp according to the present invention together with a lighting method, and FIG. 2 is a graph showing the relationship between hot cathode power and emitter coating amount of the same embodiment. Figure 3 is a graph showing the relationship between the emitter coating amount and lamp life, Figure 4 is a graph showing the relationship between hot cathode power and lamp life, and Figure 5 is a schematic representation of the conventional lighting method. FIG. 1...Small fluorescent lamp, 1a, 1b...hot cathode, 2...emitter.

Claims (1)

[Claims] 1. In a small fluorescent lamp with a tube diameter of around φ8,
Each electrode of the fluorescent lamp is a hot cathode coated with 0.1 to 1.5 mg of emitter, and each of these electrodes has a heat cathode coated with 0.1 to 1.5 mg of emitter. A compact fluorescent lamp characterized by being turned on by applying electric power.