JP2002083566A - Electrodes for cold cathode fluorescent tubes - Google Patents

Abstract

(57) [Problem] In a conventional cold cathode fluorescent tube electrode, since a pipe-shaped electrode body is located in a discharge chamber, especially when the cold cathode fluorescent tube has a small tube diameter, the electrode body and a glass bulb are used. Since the discharge does not flow around during this time, the electron-emitting substance provided on the electrode body is not effectively used, resulting in a short lifetime and a short effective emission length. SOLUTION: According to the present invention, a cold cathode fluorescent tube electrode 4 is formed of a metal wire 4a and a plate-like electrode plate 4b, and one end of the metal wire 4a is radially arranged around the tube axis at one end. By providing a plurality of electrode plates 4b so that the surface of each electrode plate 4b is parallel to the tube axis, the electrode 4 and the glass bulb 2 are provided.
The space between the electrode plate 4b and the electrode plate 4b can be made sufficiently large, the discharge can be made at this portion, and the effective emission length can be made large. It can be effectively used, blackening can be prevented, and the life can be extended.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrode structure of a cold cathode fluorescent tube used as a light source of an illuminating device for illuminating a liquid crystal display device for a computer or the like with transmitted light from the back, for example. Reduces blackening of the tube wall and can have a long life,
The present invention relates to an electrode structure that can increase the effective emission length of a cold cathode fluorescent tube.

[0002]

2. Description of the Related Art FIGS. 7 and 8 show an example of the configuration of a conventional cold cathode fluorescent tube 90 of this type. This cold cathode fluorescent tube 90 has, for example, a glass bulb 91 having a tube diameter of about 3 mm. Electrodes 92 are sealed at both ends of the glass bulb 91, and mercury and an inert gas (not shown) are sealed in the glass bulb 91. A fluorescent substance 93 is applied to the inner surface of the glass bulb 91.

FIG. 8 is a cross-sectional view of the electrode 92 shown in FIG. 7. The electrode 92 is formed by a metal pipe such as nickel, iron, tungsten, or molybdenum at the tip of a lead wire 92a. The electrode body 92b is mounted on the inner surface of the electrode body 92b by barium oxide (BaO) or strontium oxide (Sr).
O), a metal oxide such as calcium oxide (CaO) is applied as an electron-emitting substance (emitter) 92c.

[0004]

In the conventional configuration, the electrode 92 has a large surface area by forming the electrode body 92b into a pipe shape, and the electrode body 92b is provided with the electron-emitting substance 92c. Since the tube voltage can be reduced and the power consumption of the electrode 92 itself is reduced, the luminous efficiency with respect to the power consumption is high. Since the duration of the electron-emitting substance 92c depends on the current density, it is necessary to increase the surface area of the electrode body 92b as much as possible. Therefore, the electrode body 92b has a pipe shape as described above.

However, in the conventional cold cathode fluorescent tube 90, since the distance between the inner wall of the glass bulb 91 and the electrode body 92b is short, discharge does not flow around the outer periphery of the electrode body 92b, and the vicinity of the electrode body 92b is a non-light emitting portion. As a result, the effective emission length becomes small, and even if the electron-emitting substance 92c is provided on the outer periphery of the electrode body 92b, the electron-emitting substance 92c does not contribute to the discharge. Therefore, the electron-emitting substance 92c cannot be provided sufficiently. The blackening of the tube wall caused the life to be short.

[0006]

According to the present invention, there is provided a cold cathode fluorescent tube electrode provided at both ends of a tubular glass bulb of a cold cathode fluorescent tube, wherein the electrode is a metal wire. And a plate-like electrode plate, and a plurality of the electrode plates are provided at one end of the metal wire such that each electrode plate surface is in a direction substantially parallel to the tube axis of the glass bulb. An object of the present invention is to solve the problem by providing a discharge electrode for a cold-cathode tube, which is characterized by the following.

[0007]

Next, the present invention will be described in detail based on a first embodiment shown in the drawings. FIGS. 1 and 2 show a cold cathode fluorescent tube 1 according to the present invention. The cold cathode fluorescent tube 1 has electrodes 4 sealed at both ends of a tubular glass bulb 2. Mercury, an inert gas (not shown) or the like is sealed therein, and the inside of the glass bulb 2 is coated with a phosphor 3.

The above configuration is the same as that of the conventional cold cathode fluorescent tube 90. However, in the cold cathode fluorescent tube 1 according to the embodiment of the present invention, the configuration of the electrode 4 is different. , As shown in detail in FIG.
Is formed by providing a plurality of electrode plates 4b made of nickel or the like at the tip of a metal wire 4a such as a dumet wire.

The electrode 4 will be further described. For the electrode plate 4b provided at the tip of the metal wire 4a, two flat plates made of nickel and curved in one direction are prepared, and the convex surfaces are laser welded to each other. It was joined by the above-mentioned means. Then, the electrode plate 4b is attached to the metal wire 4a by laser welding or the like so that the direction in which the electrode plate 4b is not curved is substantially parallel to the tube axis of the glass bulb 2, that is, the central axis. 2 and sealed. The electrode plate 4b is provided with the same electron-emitting substance as in the prior art on the entire surface.

In the first embodiment, as a method of sealing the metal wire 4a to the end of the glass bulb 2, a bead 4c made of glass wax is provided on the metal wire 4a. Is welded to the end of the glass bulb 2 to perform sealing. On this occasion,
The electrode wire 4a is provided so as to be located at the tube axis of the glass bulb 2, and the electrode plate 4b is also radially arranged in a direction orthogonal to the tube axis of the glass bulb 2. is there.

According to the cold cathode fluorescent tube 1 configured as described above, the surface area of the electrode plate 4B can be made sufficiently large as in the conventional case, and the space between the electrode plate 4b and the glass bulb 2 can be increased. Can be made sufficiently large, so that a discharge is also performed in this portion,
The light emission near the electrode 4 can also be used, and the effective light emission length of the cold cathode fluorescent tube 1 can be made longer.

Further, since the entire surface of the electrode plate 4b contributes to the discharge, the electron-emitting material can be effectively used, blackening can be prevented, and the cold cathode fluorescent tube 1 having a long life can be obtained. Furthermore, by bending the electrode plate 4b in a direction orthogonal to the tube axis of the glass bulb 2, it is possible to arrange a large surface area of the electrode plate 4b. The current density of the electrode 4 becomes low, and the discharge starting voltage can be reduced. This suppresses the blackening of the glass bulb 2,
It can have a long life.

Next, FIGS. 4 to 6 show a second embodiment of the present invention, which is different from the first embodiment in the electrode plate 4b. In the case of the second embodiment, the electrode plate 4b
Is composed of six flat plates, each centered on the optical axis, arranged so that each plate surface is parallel to the tube axis. In order to simplify the production, in the second embodiment, one flat plate and two flat plates whose center is bent at approximately 60 ° are prepared, and these flat plates are combined by welding, so that the flat plates are joined to each other. It is provided so as to have a positional relationship of being opened by 60 °.
The electron-emitting material is provided on the entire surface of each electrode plate 4b, and the attachment to the other glass bulbs 2 is the same as that of the first embodiment.

According to the second embodiment, the surface area of the entire electrode 4 can be made sufficiently large.
The space between the glass bulb 2 and the electrode plate 4b can be made sufficiently large, and the same effects as in the first embodiment can be obtained.

In the above two embodiments, the electrode 4
In the above description, the sealing to the glass bulb 2 is performed using a bead. However, the present invention is not limited to this. Naturally, the metal wire 4a may be directly sealed to the glass bulb.
Also, the number of electrode plates 4b is not limited to that of the above-described embodiment, but may be any suitable one. However, if the number is too small, the application area of the electron-emitting substance decreases,
If the number is too large, it is difficult for the discharge to enter the space between the electrode plates 4b. Therefore, the number of the electrode plates 4b is preferably about three to six.

Each of the electrode plates 4b may be curved as in the first embodiment, or may be bent a plurality of times to form a zigzag shape. Since it can be provided inside the glass bulb 2, the number of the electrode plates 4b can be reduced.

Further, the metal wire 4a and the electrode plate 4b can be made of the same material as the conventional one, and it is not limited to the above embodiment.

[0018]

As described above, according to the electrode 4 for the cold cathode fluorescent tube 1 of the present invention, the surface area effective for discharge can be made sufficiently large, blackening can be prevented, and the lifetime can be reduced. Can be long.

Further, since the discharge sufficiently spills into the space between the electrode 4 and the glass bulb 2, light can be emitted from this portion, so that the effective light emission length of the cold cathode discharge tube 1 can be increased. Becomes

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a first embodiment of a cold cathode fluorescent tube according to the present invention.

FIG. 2 is an enlarged sectional view showing an electrode unit of the first embodiment.

FIG. 3 is an enlarged perspective view showing an electrode of the first embodiment.

FIG. 4 is a partial sectional view showing a second embodiment of the cold cathode fluorescent tube according to the present invention.

FIG. 5 is an enlarged cross-sectional view illustrating an electrode unit according to a second embodiment.

FIG. 6 is an enlarged perspective view showing an electrode of the second embodiment.

FIG. 7 is a cross-sectional view showing a conventional cold cathode fluorescent tube.

FIG. 8 is an enlarged sectional view showing an electrode part of a conventional cold cathode fluorescent tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Cold cathode fluorescent tube 2 ... Glass bulb 3 ... Phosphor 4 ... Electrode 4a ... Metal wire 4b ... Electrode plate 4c ... Bead

Claims (3)

[Claims] In a cold cathode fluorescent tube electrode provided at both ends of a tubular glass bulb of a cold cathode fluorescent tube, the electrode comprises a metal wire and a plate-like electrode plate, and the electrode plate is provided at one end of the metal wire. A discharge electrode for a cold-cathode tube, wherein a plurality of electrodes are provided radially around a tube axis of a glass bulb so that each electrode plate surface is in a direction parallel to the tube axis. 2. The electrode plate according to claim 1, wherein the electrode plate is curved at least once in a direction perpendicular to the tube axis.
5. The electrode for a cold cathode tube according to item 1. 3. The electrode plate according to claim 1, wherein an electron-emitting substance is provided on the entire surface of the electrode plate.
4. The electrode for a cold cathode fluorescent tube according to item 1.