JP2002083571A - Cold-cathode tube light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cold-cathode tube light-emitting device ensuring stable luminance and a long life even in a low-temperature environment. SOLUTION: A transparent conductive film 2, made of a thin film of oxide containing at least one element of indium, tin and zinc, is formed on the valve surface of a cold-cathode tube 1, and a pair of linear electrodes 3 are formed on the transparent conductive film 2 in the longitudinal direction of the cold- cathode tube 1. After heating the cold-cathode tube 1 by supplying electricity to the pair of linear electrodes 3 from a direct-current power source 5 for transparent conductive film, the cold-cathode tube 1 is lit up with a power source 4 for cold-cathode tube lighting up.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a cold-cathode tube light emitting device.

[0002]

2. Description of the Related Art A cold-cathode tube light-emitting device is used as a light source for a backlight of a transmission type liquid crystal display device or a gauge of an automobile. This cold-cathode tube light emitting device is generally used in a low-temperature environment (0 ° C. or lower) as compared with a normal-temperature environment (around 25 ° C.)
It is known that the brightness is greatly reduced and the life is extremely shortened. However, liquid crystal display devices used for in-vehicle or portable information terminals and backlights for instrumentation of automobiles are sometimes used in a low-temperature environment of 0 ° C or lower, so that stable brightness and long life are required. I was

Therefore, in a cold-cathode tube light-emitting device used in a low-temperature environment, a method of winding a linear heating wire such as nichrome on the surface of the device or a method of forming a flat surface as shown in Japanese Patent Application Laid-Open No. 10-64482. A method has been used in which a heater in contact with the surface of a cold cathode tube is installed by, for example, a method of attaching a resistance heating body, and the body of the cold cathode tube is directly heated by energizing. Alternatively, as shown in JP-A-11-344708, a heater for resistance heating is attached to an outer wall provided around the cold cathode tube, the outer wall is heated by energizing, and the cold cathode tube is indirectly heated by radiant heat. Heating methods have been used.

[0004]

However, in the method of installing the heater directly on the surface of the cold-cathode tube, the heater cannot be effectively heated unless the heater is completely adhered to the cold-cathode tube, and the surface of the light source cannot be effectively heated. There was a problem that the light was partially blocked because the heater was partially covered, and the luminance was reduced. Further, in the method of indirectly heating by attaching a heater to an outer wall provided around the cold cathode tube, there is a problem that thermal efficiency is poor because the cold cathode tube and the heater are not in contact with each other.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the cold cathode tube light emitting device of the present invention increases the thermal efficiency when heating the cold cathode tube, and prevents light from being shielded by covering with a heater. For the purpose of prevention,
A transparent conductive film through which light is transmitted is formed. Further, a pair of linear electrodes is formed on the transparent conductive film in the longitudinal direction of the surface of the cold cathode tube bulb, and a DC voltage is applied to the linear electrodes to form the transparent conductive film. The configuration is such that the conductive film is energized and the cold cathode tube body is directly heated. As described above, by heating the cold cathode fluorescent lamp body using the transparent conductive film as a heater film, the transparent heater is completely adhered to the cold cathode fluorescent lamp, so that it is possible to prevent a decrease in brightness and life under a low temperature environment. . Also, by forming a pair of linear electrodes in the longitudinal direction of the surface of the cold cathode tube bulb and supplying electricity to the transparent conductive film from the linear electrodes, the electrodes are provided at both ends of the cold cathode tube and the electrodes are electrically connected. Since the distance can be reduced to about 1/100, the voltage applied to the transparent conductive film can be reduced, and heating can be performed effectively with small power. In addition, even if the sheet resistance value of the transparent conductive film is high, the distance between the electrodes is small, so that the thickness of the transparent conductive film can be reduced, thereby shortening the process and time required for forming the film, and reducing the luminance. Can be prevented.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of a cold-cathode tube light emitting device according to the present embodiment, and FIG.
FIG. 2 is a cross-sectional view of the cold-cathode tube light emitting device of the present embodiment, taken along line AA ′. 1 and 2, 1 is a cold cathode tube, 2 is a transparent conductive film, 3 is a linear electrode, 4 is a power supply for lighting the cold cathode tube, and 5 is a DC power supply for the transparent conductive film.

[0007] In FIG. 1 and FIG.
Is formed directly on the glass bulb of the cold cathode tube 1 having a diameter of 2.6 mm and a length of 220 mm. The formation method is
A solvent of an organic metal containing indium and tin is uniformly sprayed onto the glass surface of the cold cathode tube 1 by a spray coating method, and is baked at 500 ° C. to be fixed.
The film thickness of this transparent conductive film 2 is 1000 °, and the decrease in luminance due to coating the film is 2% in the total luminous flux.

On this transparent conductive film 2, a linear electrode 3 for supplying electricity is formed in the longitudinal direction of the glass tube. As shown in FIG. 1 and FIG. 2, the shape is linearly formed at a position facing the glass bulb, and one end of the glass bulb serves as a lead wire extraction portion to the DC power supply 5 for the transparent conductive film so as not to contact with each other. The electrode has a width of 0.5 mm in the linear portion. The forming method is such that a paste containing silver and palladium is applied and baked.

The linear electrode 3 and the DC power source 5 for the transparent conductive film
Are connected via a lead wire. The electrodes at both ends of the cold-cathode tube 1 and the cold-cathode tube lighting power supply 4 are connected via lead wires. With the above configuration, a cold-cathode tube light emitting device is formed.

When this cold-cathode tube light emitting device is used in a low-temperature environment, first, a DC 10 V
Is applied to the transparent conductive film 2 through the linear electrode 3, the transparent conductive film 2 serves as a heater, and the cold cathode tube 1 is heated to 50 ° C. to 70 ° C. Thereafter, power is supplied to the cold-cathode tube 1 from the cold-cathode tube lighting power supply 4 (600 V, 6 mA is input via an inverter),
The cold-cathode tube 1 is turned on as in the normal temperature environment.

This cold-cathode tube light emitting device was installed in a low-temperature environment of 0 ° C., and the luminance and the life were measured. For comparison, measurements were also performed when a cold cathode tube without a normal transparent conductive film was installed in a low-temperature environment of 0 ° C. and when the cold cathode tube was installed in a normal temperature (25 ° C.) environment. The results are shown in (Table 1). The luminance is represented by the initial value of the total luminous flux (unit: lm: lumen), which is the amount of light emitted from the light source in all directions.
It represents a short time among the lighting times until it drops to 0%.

[0012]

[Table 1]

As described above, when a cold cathode tube in which a normal transparent conductive film is not formed is placed in a low-temperature environment, the luminance is reduced to １ ／ or less,
Although the life is reduced to 1/20 or less, the same brightness and life can be maintained in a low-temperature environment as in a normal-temperature environment by forming a transparent conductive film and supplying electricity thereto to heat the cold-cathode tube. .

In this embodiment, the spray coating method is used for forming the transparent conductive film. However, the other method, that is, the sol-gel dipping method or the coating method may be used.
A method of fixing by coating on a glass surface and baking, or a thin film forming method such as a plasma CVD method, a thermal CVD method, an evaporation method, and a sputtering method can be formed by selecting film forming conditions.

In this embodiment, an indium and tin oxide thin film is used for the transparent conductive film. However, an oxide film containing at least one element of other composition, that is, indium, tin and zinc is used. Then, the same effect can be obtained.

Further, in this embodiment, the thickness of the transparent conductive film is 1000 °, but depending on the sheet resistance of the film and the output of the DC power supply for the transparent conductive film, it is 300 ° to 3000 °.
Within the range, the same effect can be obtained, and the decrease in luminance due to coating of the film is 5% or less in the total luminous flux.

In the method of forming a linear electrode according to the present embodiment, a paste containing silver and palladium is applied and baked, but a paste containing another metal element is used. The same effect can be obtained if the metal thin film is linearly formed by masking on the surface of the transparent conductive film by using a thin film forming method such as vapor deposition or sputtering method. Needless to say,

[0018]

According to the cold-cathode tube light emitting device of the present invention, the cold-cathode tube can be efficiently heated with low power consumption by the transparent conductive film adhered to the cold-cathode tube main body and the linear electrodes thereon. . Further, by disposing the linear electrodes in the longitudinal direction of the cold-cathode tube, the thickness of the transparent conductive film can be reduced, and a decrease in luminance due to the installation of the heater film can be minimized. Due to the above-described effects unique to the present invention, the same brightness and lifetime can be realized even in a low-temperature environment (0 ° C. or less) as in a normal-temperature environment (around 25 ° C.). Is significantly improved.

[Brief description of the drawings]

FIG. 1 is a schematic view of a cold-cathode tube light emitting device of the present invention.

FIG. 2 is a cross-sectional view of the cold-cathode tube light emitting device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cold-cathode tube 2 Transparent conductive film 3 Linear electrode 4 Power supply for cold-cathode tube lighting 5 DC power supply for transparent conductive film

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Eiji Fujii 1006 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Term (reference) 3K083 AA05 AA62 EA02 5C039 AA08

Claims (5)

[Claims] 1. A transparent conductive film on a surface of a cold-cathode tube bulb,
A cold-cathode tube light emitting device comprising a pair of linear electrodes for supplying a current to the transparent conductive film. 2. The cold-cathode tube light emitting device according to claim 1, wherein the transparent conductive film is a thin film of an oxide containing at least one element of indium, tin and zinc. 3. The transparent conductive film has a thickness of 300 to 30.
2. The cold-cathode tube light emitting device according to claim 1, wherein the angle is in the range of 00 [deg.]. 4. The cold-cathode tube light emitting device according to claim 1, wherein the pair of linear electrodes are arranged in the longitudinal direction of the cold-cathode tube bulb. 5. The cold-cathode tube light-emitting device according to claim 1, wherein a DC voltage is applied to the pair of linear electrodes to energize the transparent conductive film and heat the cold-cathode tube body.