JPH024097B2 - - Google Patents

Description

[Detailed description of the invention] TECHNICAL FIELD This invention relates to compact fluorescent lights.

Recently, new products such as wristwatch-type televisions and pocket televisions have been developed, and the screens of these televisions are formed of liquid crystal elements. In the case of pocket televisions, electroluminescence is used as a backlight to illuminate the liquid crystal element. This electroluminescence
It has the advantage of being small and low power consumption, but on the other hand,
There is a problem that the brightness is not sufficient and the screen is therefore dark.

For this reason, it has been proposed to use a compact fluorescent light as the backlight. In the current state of development of LCD color TVs, 2- to 3-inch models are the mainstream, and because they use batteries, small models with a total lamp length of 120 mm or less and power consumption of 1.5 W or less are required. . However, if a fluorescent lamp is made small like this, the luminous efficiency will be low and it will not be possible to obtain sufficient brightness.On the other hand, if you try to obtain a sufficiently bright light by increasing the luminous efficiency, the power consumption will be large. It has the disadvantage of getting used to it. This is because, due to the low power consumption, the calorific value of the hot cathode type filament electrode is small and the temperature of the lamp does not rise sufficiently, and the coldest point temperature is low so that mercury does not evaporate sufficiently. is short, so the electrode spacing is also shortened, but the length of the cathode dark area in front of the cathode, which does not contribute much to light emission, does not decrease in proportion to the electrode spacing, and the ratio of the effective positive column between the electrodes to the electrode spacing This is because the luminous efficiency decreases due to a decrease in the luminous efficiency.

The present invention was made based on the above-mentioned circumstances, and an object of the present invention is to provide a fluorescent lamp that is small in size, consumes little power, has good luminous efficiency, and can provide sufficient brightness. This purpose is to provide a compact fluorescent lamp with a total lamp length of 120 mm or less and a power consumption of 1.5 W or less, characterized in that the filament electrode is disposed within 10 mm from the end of the lamp. achieved by. Furthermore, by covering the glass enclosure near the filament electrode with a heat insulating material, the luminous efficiency can be improved more reliably.

The present invention will be specifically described below based on embodiments shown in the drawings.

FIG. 1 shows an explanatory cross-sectional view showing an example of a compact fluorescent light according to the present invention and its temperature distribution. The inner wall surface is coated with a fluorescent film. The filament 2 constituting the electrode is made of a high melting point metal such as tungsten or molybdenum, and is fixed near both ends inside the glass enclosure 1 by lead wires 3 made of dumet wire, copper wire, or the like. The filament 2 may be in the form of a single or double coil, or in the form of a straight line, but in any case it is lightweight; for example, the weight of the portion to which the electron emitter is fixed is about 0.3 to 3.0 mg. This is because the heat capacity decreases due to weight reduction, which makes it easier to raise the temperature even if power consumption is reduced, and lighting performance is improved. As the material for the electron emitter, oxides or carbonates of alkali metals or alkaline earth metals, and various other materials are used.
One of the filaments 2 at both ends functions as a hot cathode when lit with direct current, and both function as hot cathodes when lit with alternating current.
The fixed position of filament 2 is a distance l from the end.
is within 10mm, which is shorter than with conventional fluorescent lights. The glass enclosure 1 near the filament 2 is coated with a heat insulating material 4. Although this insulation material 4 is not necessarily necessary,
By covering this part, the heat radiation from this part can be reduced and the temperature can be easily raised.

A small amount of mercury, for example, about 1 to 2 mg, is sealed in the glass enclosure 1, and a gas selected from argon, krypton, or neon, or a mixed gas thereof, of about 6 to 50 torr is sealed, Operates with power consumption of 1.5W or less.

Next, an example of an actually produced fluorescent light will be shown.

Total length L 80mm Inner diameter D 6.45mm Electrode spacing 59mm Distance from end l 4mm Filled gas Argon filled gas 15 torr Mercury amount 1mg Filament Tungsten (MG=2.67) Electronic emitter Triple carbonate and zirconia mixture Voltage, current 45V, 15mA Power consumption 0.67 W When this small fluorescent lamp is turned on, the coldest point is located behind the filament 2 and in front of the end face of the glass envelope 1. When the distance l from the lamp end of the filament 2 is large as in a conventional fluorescent lamp, the temperature at the coldest point is lower than that at the center, as shown by the dotted line curve in Figure 1, and the mercury The vapor pressure was low and the luminous efficiency was poor. On the other hand, the compact fluorescent light according to the present invention is characterized in that the distance l is as small as 10 mm or less, and the position of the coldest point is close to the filament 2, which is the heating element. As shown by the solid curve in FIG. 1, the temperature is raised to a temperature that is almost the same as that of the central portion.
Therefore, the vapor pressure of mercury increases and luminous efficiency improves. Next, since the distance l is small, the arc length becomes longer. Therefore, even though the total length is a short constant value, the positive column that effectively contributes to light emission becomes longer and the brightness is improved.

When the compact fluorescent lamp with the above configuration is actually turned on and its brightness is measured, it is found that at an ambient temperature of 20°C, it is approximately
It was large at 7,000 nt, and remained bright enough for practical use even after 2,000 hours of continuous lighting. Therefore, when used as a backlight for a liquid crystal element, the screen can be made sufficiently bright, which is a great practical advantage.

As explained above, the compact fluorescent light of the present invention is
It is a fluorescent lamp with a total lamp length of 120 mm or less and a power consumption of 1.5 W or less, and the filament electrode is located within 10 mm from the end of the lamp, so the coldest point temperature is As it rises, the arc length becomes longer, which improves the luminous efficiency. Therefore, according to the present invention, it is possible to provide a fluorescent lamp that is small in size, consumes little power, has good luminous efficiency, and can provide sufficient brightness.

[Brief explanation of drawings]

FIG. 1 is an explanatory sectional view and temperature distribution diagram showing an example of a compact fluorescent light according to the present invention, and FIG. 2 is an enlarged sectional view of the main parts. 1...Glass enclosure, 2...Filament, 3...
...Lead wire, 4...Insulation material.

[Claims]

1. A fluorescent lamp driven by a high-frequency lighting circuit with direct current or a lame upper and lower waveform, and with a power consumption of 1.5 W or less, one electrode of which is a hot cathode type and the other electrode which is also used as a mercury-impregnated getter. A small fluorescent light.