JPH0452929Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Technical Field) The present invention relates to a single-end type fluorescent lamp mainly used for display elements such as large-sized color display devices.

(Background Art) The present inventor proposed a single-ended fluorescent lamp having a structure as shown in FIG. 4 as a display element for a large color display device. In such a lamp, the tip of a glass bulb 1 is approximately hemispherical, the inner surface is coated with a phosphor 2, and the other end of the glass bulb 1 is sealed with a glass stem 3 having three lead wires. ing. Between two of the three lead wires, a cathode filament 4 coated with an electron radioactive material is installed parallel to the axial direction of the lamp, and the surface of the other lead wire is It is covered with an electrical insulator 5, and an anode 6 is attached to the tip. Furthermore, a discharge gas consisting of mercury and an inert gas such as argon is sealed inside the glass bulb 1 . Note that the display surface is the tip of the glass bulb 1.

Such single-ended fluorescent lamps have a minimum outer diameter of 7 mm.
However, it has a very wide range of applications as a display element, but it has the following problems regarding lamp characteristics. That is,
Since the cathode filament 4 is mounted parallel to the axial direction of the lamp, the distance between the cathode and anode varies depending on the position of the hot spot formed on the cathode 4. The position of the hot spot differs from lamp to lamp due to variations in the application position of the electrode material, inclination of the filament, etc., and also differs depending on the lighting time of the same lamp due to wear of the electrode material. As the position of the hot spot changes, the electrical characteristics change. Variations in electrical characteristics lead to variations in brightness and lifespan, degrading the quality of the lamp.

(Purpose of the invention) The present invention was devised in view of the above-mentioned problems, and its purpose is to provide a small single-ended fluorescent lamp with less variation in electrical characteristics.

(Disclosure of the invention) The invention will be described below based on examples. FIG. 1 shows an embodiment of the present invention.The configuration differs from the conventional example in that one of the three lead wires is used as it is as the anode 6, and the rod-shaped anode 6 has the same length as the cathode filament 4 and is arranged parallel to the filament 4, as shown in FIG. 1b. The other configurations are similar to those of the conventional example, so
Explanation will be omitted by assigning the same reference numerals to equivalent configurations.

Figure 2 shows the basic circuit for lighting the above-mentioned lamp. In the figure, DC1 is a direct current for causing a main discharge between the cathode 4 and anode 6, and DC2 is a direct current for constantly preheating the cathode 4. The power supply, R is a resistor as a current limiting element, and SW is a switch for lighting the lamp (actually, it turns on and off quickly depending on the input signal).
(transistor switch that operates off).

The lamp starts discharging immediately when the switch SW is turned on while the cathode 4 is preheated by the preheating power supply DC2 and a voltage is applied between the cathode 4 and the anode 6 by the main power supply DC1. Since the facing distance between the cathode 4 and the anode 6 is designed to be short, the lamp can be started with a low voltage of 30V or less.

By the way, in the lamp according to the present invention, the cathode filament 4 and the anode 6 are arranged in parallel, so that no matter where a hot spot is formed on the cathode filament 4, the shortest distance from that position to the anode 6, that is, the electrode The distances between the lamps are the same, and the electrical characteristics of the lamp are always constant.

The outer diameter of glass bulb 1 is 7.0mm, 13.5mm, 20.0mm
Three types of prototype lamps, each filled with a discharge gas consisting of mercury and argon and coated with a blue-emitting phosphor, achieved a luminance of 1000 to 1500 cd/m ² . This value is a sufficient level of brightness for indoor to semi-outdoor display elements.

Next, FIG. 3 shows a different embodiment of the present invention, and the difference from the previous embodiment is that one of the legs is approximately
The point is that the cathode filament 4 bent by 90° is used.
By using such filament 4,
There is an advantage that the lead wire of the glass stem 3 can be used without any bending. Also,
It is possible to prevent the shadow of the lead wire from appearing on the top of the lamp, and it is also possible to further shorten the overall length of the lamp.

(Effects of the invention) As described above, this invention consists of disposing a cathode filament and an anode inside a cylindrical glass bulb with a substantially hemispherical tip and coated with a phosphor on the inside, and enclosing a discharge gas. In the single-ended fluorescent lamp, the cathode filament is arranged parallel to the axial direction of the glass bulb, and the anode is constituted by a rod-shaped body having approximately the same length as the cathode filament, and By arranging the rod-shaped body parallel to the cathode filament, the distance between the electrodes is the same no matter where a hot spot is formed on the filament, and therefore the electrical characteristics change very little from lamp to lamp or from lighting time to lamp and are stable. Therefore, it was possible to provide a single-ended fluorescent lamp with low luminance variation.

[Brief explanation of drawings]

Fig. 1a is a plan view showing an embodiment of the present invention, Fig. 1b is a front view of the same as above, Fig. 2 is a basic circuit diagram for lighting a lamp according to the present invention, and Fig. 3 is a plan view of the present invention. FIG. 4 is a front view of a conventional example. 1... Glass bulb, 2... Fluorescent material, 4... Cathode filament, 6... Anode.

Claims (1)

[Scope of utility model registration request] In a single-cap type fluorescent lamp, a cathode filament and an anode are disposed inside a cylindrical glass bulb having a substantially hemispherical tip and a phosphor coated on the inner surface, and a discharge gas is sealed therein. The filament is arranged parallel to the axial direction of the glass bulb, and the anode is composed of a rod-shaped body having approximately the same length as the cathode filament, and the rod-shaped body is arranged parallel to the cathode filament. A single-end molded fluorescent lamp.