JP2003178713A - Cold cathode fluorescent lamp and illumination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cold cathode fluorescent lamp and an illumination device that have high luminance maintenance factor and long life and contribute to performance improvement of OA equipment and liquid crystal devices. <P>SOLUTION: This is a cold cathode fluorescent lamp 11 that comprises a glass tube 1 on the inner wall of which a phosphor layer 2 is provided and mercury and rare gas are filled as a discharge media, a lead wire 3 that is sealed and introduced opposed to each other at both ends in the glass tube 1 and is connected to a lead wire for outside feeding, and a discharge electrode 4 that is respectively electrically connected to the facing top end of the lead wire 3. A metal oxide layer 5 having high affinity to mercury is coated on the phosphor layer 2 in the region excluding the main irradiation face 6 of the above cold cathode fluorescent lamp 11. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold cathode fluorescent lamp and an illuminating device, and more particularly to a cold cathode fluorescent lamp and an illuminating device exhibiting a high luminance maintenance rate for a long time.

[0002]

2. Description of the Related Art For example, a light source for a liquid crystal display, or a light source for reading characters / images such as a scanner, or an exposure light source is required to have higher performance, smaller size, and longer life as the application is expanded or spread. Is required. In response to such demands, for example, fluorescent lamps (low-pressure discharge lamps) as light sources for backlights are inevitably required to have higher performance such as high performance and long life due to their thin tube shape. There is.

4 (a) and 4 (b) show a schematic structure of a cold cathode fluorescent lamp conventionally used as a light source for a backlight, etc. FIG. 4 (a) is a cross sectional view, FIG.
(B) is a longitudinal sectional view. In FIGS. 4 (a) and 4 (b), reference numeral 1 denotes a glass tube (in which an inner wall surface is provided with a phosphor layer 2 that emits light when stimulated by ultraviolet rays, and a rare gas such as neon or argon and a mercury-based discharge medium are enclosed ( Glass bulbs), 3 and 3 are a pair of introduction wires that are sealed and introduced so as to face both ends of the glass tube 1 and are connected to external power supply lead wires (not shown), and 4 and 4 are the glass tubes. The discharge electrodes are electrically connected to the opposing tip portions of the lead-in wires 3 and 3 which are sealed and introduced into the inside 1.

Here, the glass tube 1 has an inner diameter of 1.2 to 12
The length is about mm and the length is about 40 to 800 mm. Further, in the glass tube 1, for example, 0.5 to 2.0 mg / c
Mercury of about m ³ and 60 to 150 Torr (8 to 19 k
A rare gas of about Pa) is enclosed as a discharge medium.
Further, in the above configuration, the discharge electrodes 4 and 4 have an inner diameter of about 0.6 to 6.0 mm and a wall thickness of 0.1 to 0.2 m, for example.
It is configured by a cylindrical body (for example, a nickel cylindrical body) having a length of about m and a length of about 2 to 10 mm. And the lead-in line 3,
When electricity is applied to the discharge electrodes 4 and 4 via 3, ultraviolet rays are radiated in the glass tube 1, and the ultraviolet rays are converted into visible light by the phosphor layer 2 to function as a fluorescent lamp.

[0005]

By the way, the cold cathode fluorescent lamp having the above-mentioned structure is usually selected with a large amount (excess) of mercury in the discharge medium for the purpose of extending the life. Here, the excessive amount of enclosed mercury is
Aggregates in a relatively low temperature region in the glass tube 1. That is, since the phosphor layer 2 on the inner wall surface of the glass tube 1 exhibits a substantially uniform affinity for mercury, regardless of whether or not it is the irradiation surface area due to the adhesion of mercury, the phosphor layer 2 is aggregated / covered in the low temperature area. I will wear it.

The mercury agglomeration in the above-mentioned low temperature region raises a so-called blackening problem, resulting in a decrease in the luminance of the agglomerated region or a change in the luminance retention rate. That is, as the lighting time elapses,
The uniformity of overall light emission and brightness is impaired, and
The maintenance factor of the brightness is also lowered, and the state in which the required function cannot be sufficiently achieved is exhibited. Here, the problem of lowering the light emission / luminance maintenance factor is that, for example, when the liquid crystal device is used as a front light, the mercury agglomeration portion is visually recognized as a shadow, and when it is used as a reading light source such as a scanner, the mercury agglomeration is observed. Part causes a decrease in reading sensitivity.

As described above, the measure for extending the life of the cold cathode fluorescent lamp by encapsulating excess mercury causes the undesired problem of being visually recognized as a shadow on the exposed surface or reducing the reading sensitivity. Is concerned. That is,
High brightness maintenance rate and long life, which are desired for general illumination light sources, exposure light sources for copying machines, original light sources for facsimiles, front light sources for liquid crystal devices, and light sources for backlights. In addition,
It cannot be said that it can respond sufficiently.

The present invention has been made in consideration of the above circumstances, and achieves a high luminance maintenance rate or a long life, and
An object of the present invention is to provide a cold cathode fluorescent lamp and a lighting device that contribute to improving the performance of devices and liquid crystal devices.

[0009]

According to a first aspect of the present invention, there is provided a glass tube having a phosphor layer provided on an inner wall surface thereof, in which mercury and a rare gas are sealed as a discharge medium, and a glass tube facing both ends of the glass tube. Cold cathode fluorescent lamp having an introduction wire that is sealed and introduced to connect to an external power supply lead wire, and a discharge electrode that is electrically connected to opposite end portions of the introduction wire that is sealed and introduced into the glass tube. The cold cathode fluorescent lamp is characterized in that a metal oxide layer having a high affinity for mercury is coated on the phosphor layer in a region other than the main irradiation surface of the cold cathode fluorescent lamp. .

According to a second aspect of the present invention, in the cold cathode fluorescent lamp according to the first aspect, the metal oxide having a high affinity for mercury is Si, Fe, Zr, Cr, Ti, Sn, G.
It is characterized by being an oxide containing at least one metal element of e, Ta, V and Zn.

According to a third aspect of the present invention, in the cold cathode fluorescent lamp according to the first or second aspect, the coating of a metal oxide having a high affinity for mercury is 180 in the circumferential direction.
It is characterized in that it is formed in a belt shape of ° or less.

The invention of claim 4 is the cold cathode fluorescent lamp according to any one of claims 1 to 3, characterized in that the outer diameter of the glass tube is 10 mm or less.

According to a fifth aspect of the present invention, there is provided a lighting device having a fluorescent lamp and a lighting device main body capable of mounting and lighting the fluorescent lamp, wherein the fluorescent lamp is any one of the first to fourth aspects. It is an illuminating device characterized by being the cold cathode fluorescent lamp described.

That is, the invention of claims 1 to 4 is a cold cathode fluorescent lamp in which a rare gas and mercury are enclosed as a discharge medium in a glass tube and a pair of discharge electrodes are sealed at both ends in the glass tube. The main point is to cover and dispose a metal oxide layer having a high affinity for mercury on a part of the area other than the main irradiation surface or on the entire phosphor layer surface. In other words, paying attention to the fact that mercury tends to be positively charged, metal oxides (composite oxides) having a high negative affinity for mercury are formed on the surface of the phosphor layer except the main irradiation surface. (Including) is applied (coated).

Due to the tendency of the metal oxide layer to be negatively charged, excess mercury is selectively aggregated (dense) on the surface of the phosphor layer excluding the main irradiation surface, and no shadow is generated on the main irradiation surface side. Prevents a decrease in brightness. In other words, a metal oxide having a negative charging tendency is coated on the surface of the phosphor layer in the area (for example, the reflector side) excluding the main irradiation surface that does not interfere with light emission and irradiation, and positively charged mercury is applied to this. This is intended to prevent or avoid a decrease in brightness on the irradiation surface side due to the agglomeration of mercury by selective electrostatic action.

In the inventions of claims 1 to 4,
Metal oxides (including complex oxides) applied (covered) on the phosphor layer surface of the area excluding the main irradiation surface of the cold cathode fluorescent lamp
Is, for example, Si, Fe, Zr, Cr, Ti, Sn, G
It is at least one oxide of e, Ta, V, and Zn, or a composite oxide containing at least two of the above metal elements. Here, the application (coating) to the surface of the phosphor layer is performed by applying and baking the dispersion liquid of the metal oxide fine particles or the like.

The deposition area and the form of the metal oxide layer having a high affinity for mercury are determined by the usage of the cold cathode fluorescent lamp. That is, when the main irradiation surface is in the circumferential direction of the glass tube, for example, about 120 °, about 180 °, 210 °, etc., when the usage form corresponding to the aperture type is adopted, the main irradiation is performed. In the circumferential direction of the glass tube, which is the area other than the area,
For example, within 240 °, within 180 °, 170
It is set on the phosphor layer surface within about °. In general, considering the versatility of usage, it is 18
It is desirable to select and set within 0 °. The metal oxide layer may be applied / coated (coated) uniformly or in spots or islands on the entire surface of the corresponding phosphor layer, or may be striped or spotted in a part of the corresponding region. Or it may be island-shaped.

In the inventions of claims 1 to 4,
The glass tube generally has an inner diameter of about 1.2 to 12 mm and a length of about 40 to 800 mm, and in the glass tube 1, as a discharge medium, for example, one or more kinds of neon, argon, krypton, xenon, etc. are used. Rare gas 60-150To
rr (8 to 19 kPa) and mercury 0.5 to 2.5
A discharge medium of about mg / cm ³ is enclosed.

In the inventions of claims 1 to 4,
The discharge electrode has, for example, an inner diameter of about 0.6 to 6.0 mm, a wall thickness of about 0.1 to 0.2 mm, and a length of about 2 to 10 mm,
In addition, the inner wall surface is made of a metal cylinder having a concavo-convex structure made of nickel, tantalum, or molybdenum.
Then, the discharge electrode is electrically connected to the metal cylindrical body, and a required electric power is applied from the outside through an introduction wire that seals and guides the end portion of the glass tube.

In the inventions of claims 1 to 4,
The lead wire to be fed from the outside is made of, for example, a tungsten-based or molybdenum-based metal or a composite metal in which nickel is clad with copper, and the glass tube sealing part (the glass tube sealing part connected to the discharge electrode is The diameter of (including) is, for example, about 0.3 to 0.8 mm. The lead-out portion of the lead-in wire outside the glass tube (the connection portion with the lead wire for external power feeding) is
If the energization area is made larger than that of the glass tube sealed portion, the current density can be suppressed to a small value, so that the heat generation of the discharge electrode portion due to the external power supply can be suppressed or reduced.

In the invention of claim 5, the main body of the illuminating device capable of mounting and lighting a fluorescent lamp is a general luminaire main body, a light source for exposure and a light source for reading of OA equipment, and a front light of a liquid crystal device. Light source devices for backlights and light source devices for backlights.

In the inventions of claims 1 to 4, a metal oxide having a high negative affinity for mercury is deposited on the surface of the phosphor layer excluding the main irradiation surface. As a result, excess mercury is agglomerated or concentrated as a discharge medium. In other words, since the excess mercury is aggregated or concentrated in the region that does not affect irradiation, even if the phenomenon of so-called blackening occurs, there is no fear that the maintenance factor of the luminance will decrease, and high light emission over a long period of time will be achieved.・ Maintain brightness.

According to the invention of claim 5, the cold cathode fluorescent lamp forming the light source can endure long-term lighting and exhibits a high luminance maintenance rate, so that it is possible to easily improve the performance of OA equipment, liquid crystal devices and the like. Is possible.

[0024]

DETAILED DESCRIPTION OF THE INVENTION An embodiment will be described below with reference to FIGS.

FIG. 1 is a vertical cross-sectional view showing the structure of essential parts of a cold cathode fluorescent lamp according to an embodiment, which is basically the same as that shown in FIG.
The structure is as shown in. In FIG. 1, 1 is a glass tube in which a phosphor layer 2 which emits light upon stimulation with ultraviolet rays is provided on the inner wall surface, and a rare gas and mercury are enclosed, and 5 is
It is a SiO ₂ layer having a thickness of about μm deposited and formed on the surface of the phosphor layer 2 and in the region excluding the main irradiation surface 6. A pair of discharge electrodes are sealed so as to face both ends of the glass tube 1.

Here, the glass tube 1 has, for example, an outer diameter of 3.
0 mm, length 200 mm, for example 2.5 mg / cm
^{About 3} mercury and about 80 Torr (10 kPa) neon, argon and other rare gases are enclosed. The discharge electrode is composed of a nickel cylindrical body.

Further, the discharge electrode is the glass tube 1.
The leading end of the lead-in wire, which is sealed and led out at the end of, is inserted or fitted into the reduced diameter portion of the cylindrical body, and the outer peripheral portion is 0.9 mm, the inner diameter is 0.6 mm, and the length is 2.8 mm, and At least the inner wall surface of the side is joined to a cylindrical body made of tantalum metal by means of spot welding or the like on the inner wall of the cylindrical body, which has an uneven surface, for mechanical fixing and electrical connection. Here, the lead-in wire is made of molybdenum, for example, and the outer diameter is 1.0 mm on the side of the portion that is sealed / sealed to the glass tube 1.
The rod-shaped body and the connecting portion of the external power supply lead wire with the conductive wire are formed into a cylindrical shape having an outer diameter of about 2.0 mm, an inner diameter of about 0.5 mm, and a length of about 1.5 mm.

In the structure of the cold cathode fluorescent lamp described above, the pair of discharge electrodes are energized through the lead-in wire, and the energization causes the ultraviolet rays to be radiated. In the process of acting as a light source, it functions as a fluorescent lamp in which a change in the luminance maintenance factor due to the aggregation of mercury in the low temperature portion, which has been encountered in conventional fluorescent lamps, is suppressed / prevented.

The cold cathode fluorescent lamp having the above structure was subjected to a continuous lighting test under the conditions of an ambient temperature of 25 ° C. and a lamp current of 5 mA. As shown, it was confirmed that even after 10,000 hours or 12,000 hours, about 75% of the brightness at the beginning of lighting was maintained and exhibited, and the life and luminous efficiency were excellent. For comparison, in the structure of the cold cathode fluorescent lamp according to this example, S is formed on the surface of the phosphor layer 2.
A change in the luminance ratio on the main irradiation surface was examined under the same conditions and under the same conditions except that the iO ₂ layer was not provided. Met. That is, in the case of the comparative example, the lighting test 700
When 0 hours had elapsed, the brightness was reduced to about 60% of the initial lighting.

Next, an application example of the cold cathode fluorescent lamp will be described. FIG. 3 is a cross-sectional view showing a main configuration of a backlight unit of a liquid crystal device. In FIG. 3, reference numeral 7 denotes a light guide plate, for example, an acrylic resin-based transparent plate, on which a light diffusion sheet 8 is arranged on one main surface side forming a radiation surface, and a reflector sheet 9 is arranged on the other main surface side. Further, a cold cathode fluorescent lamp 11 with a reflector 10 is mounted and arranged on one end surface side of the light guide plate 7.

Here, the light diffusion sheet 8 is made of, for example, acrylic resin, the reflector sheet 9 is made of white-colored polyethylene terephthalate resin, and the reflector 10 is made of mirror-finished metal or white. Made of colored polyethylene terephthalate resin. The cold cathode fluorescent lamp 11 has a main irradiation surface 6
Is mounted and arranged so as to face one end surface of the light guide plate 7.

In the backlight unit having the above-described structure, when the electric power is input to the cold cathode fluorescent lamp 11, the ultraviolet rays generated by the discharge between the pair of discharge electrodes are converted into visible light by the phosphor layer 2. At this time, a part of the surface of the phosphor layer 2 on the inner wall surface of the cold cathode fluorescent lamp 11, in other words, the surface of the phosphor layer 2 excluding the main irradiation surface 6 has a high affinity for mercury. Since the metal oxide layer 5 is deposited, excessive mercury is adsorbed or aggregated on the surface of the metal oxide layer 5 during the lighting operation.

That is, the excess mercury in the cold cathode fluorescent lamp 11 has almost no effect on the irradiation.
Since it is agglomerated on the surface and the adsorption / aggregation on the main irradiation surface 6 is suppressed or avoided, the main irradiation is hardly affected. Therefore, a change in the brightness of light incident on the light guide plate 7 from the main irradiation surface 6 of the cold cathode fluorescent lamp 11 is also suppressed, and in a continuous lighting operation, light having a high brightness ratio is guided through the light guide plate 7 and It will be irradiated from the diffusion plate 8.

The present invention is not limited to the above embodiments, but various modifications can be made without departing from the spirit of the invention. For example, the diameter and length of the glass tube that forms the arc tube, the distance between the discharge electrodes, the type of phosphor that forms the phosphor layer, and high affinity for mercury (negative charging tendency)
It is possible to appropriately change and set the type of the metal oxide having the above and the form of the metal oxide layer.

[0035]

According to the first to fourth aspects of the present invention, since the excess mercury is aggregated or concentrated in the region that does not affect the irradiation, even if a so-called blackening phenomenon occurs, the luminance maintenance rate is high. Light emission for a long time
A cold cathode fluorescent lamp that maintains brightness is provided.

According to the fifth aspect of the present invention, since the cold cathode fluorescent lamp, which has sufficient durability for long-term lighting and exhibits a high luminance maintenance rate, is used as the light source, it greatly contributes to the performance improvement of OA equipments, liquid crystal devices and the like. .

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing the configuration of a main part of a cold cathode fluorescent lamp according to an embodiment.

FIG. 2 is a characteristic diagram showing a comparison between a lighting time and a luminance maintenance rate of a cold cathode fluorescent lamp according to an example and a conventional cold cathode fluorescent lamp.

FIG. 3 is a cross-sectional view showing a main configuration of a lighting device according to an embodiment.

4A and 4B show a configuration of a main part of a conventional cold cathode fluorescent lamp, in which FIG. 4A is a horizontal sectional view and FIG. 4B is a vertical sectional view.

[Explanation of symbols]

1 ... Glass tube 2 ... Phosphor layer 3 ... Introduction line 4 ... Discharge electrode 5: Metal oxide layer having a high affinity for mercury 6 ... Main irradiation surface 7 ... Light guide plate 8: Light diffusion plate 9 ... Reflector sheet 10 ... Reflector 11 ... Cold cathode fluorescent lamp

Claims (5)

[Claims] 1. A glass tube in which a phosphor layer is provided on an inner wall surface, and mercury and a rare gas are enclosed as a discharge medium, and a lead wire for external power feeding, which is sealed and introduced so as to face both ends of the glass tube. Is a cold cathode fluorescent lamp having a discharge electrode electrically connected to each of the introduction lines connected to the discharge tube and the opposite ends of the introduction line sealed and introduced into the glass tube. A cold cathode fluorescent lamp characterized in that a metal oxide layer having a high affinity for mercury is deposited on a phosphor layer in a region excluding an irradiation surface. 2. A metal oxide having a high affinity for mercury is Si, Fe, Zr, Cr, Ti, Sn, Ge, T.
The cold cathode fluorescent lamp according to claim 1, which is an oxide containing at least one metal element of a, V, and Zn. 3. The cold cathode according to claim 1, wherein the coating of a metal oxide having a high affinity for mercury is formed in a band shape of 180 ° or less in the circumferential direction. Fluorescent lamp. 4. The cold cathode fluorescent lamp according to claim 1, wherein the glass tube has an outer diameter of 10 mm or less. 5. A lighting device having a fluorescent lamp and a lighting device body capable of mounting and lighting the fluorescent lamp,
An illumination device, wherein the fluorescent lamp is the cold cathode fluorescent lamp according to any one of claims 1 to 4.