JP3666647B2 - Method for manufacturing a cold cathode fluorescent discharge tube - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a cold cathode fluorescent discharge tube, and more particularly to a technique for forming a fluorescent film on the inner wall of a glass thin tube.
[0002]
[Prior art]
A backlight system is widely adopted in liquid crystal monitors, liquid crystal televisions, and the like connected to computers, and cold cathode fluorescent discharge tubes are generally used as light sources of this backlight system. In such a cold cathode fluorescent discharge tube, it is required to obtain uniform light emission intensity and uniform light emission color, and the demand for narrowing the cold cathode fluorescent discharge tube is increasing. In other words, OA equipment and AV equipment are becoming smaller and thinner due to progress in the information and communication era and increasing mobile use. Correspondingly, cold cathode fluorescent discharge tubes as light sources such as liquid crystal monitors are made smaller and narrower. Is required. Further, in order to improve the light use efficiency when the light emitted from the cold cathode fluorescent discharge tube passes through the backlight, it is an important issue to make the discharge tube narrow.
[0003]
As is well known, a cold cathode fluorescent discharge tube forms a thin fluorescent film on the inner wall of a glass tube, and ultraviolet radiation from mercury vapor sealed inside the glass tube is converted into visible light by this fluorescent film. As a method of forming a fluorescent film on the inner wall of the glass tube, a method of sucking a fluorescent material from one opening of the glass tube and attaching it to the inner wall of the glass tube while the glass tube is upright is common. .
[0004]
That is, first, a glass tube having both ends opened is prepared, and this glass tube is placed upright with the opening at the lower end immersed in the fluorescent film forming solvent. Next, suction is performed through the opening at the upper end of the glass tube, and the internal pressure of the glass tube is made negative, so that the fluorescent film forming solvent is sucked into the glass tube and the fluorescent film forming solvent is applied to the inner wall of the glass tube. Adhere. Subsequently, after the negative pressure is released and excess fluorescent film forming solvent is discharged from the opening at the lower end of the glass tube, a drying gas is poured into the glass tube, and the fluorescent film forming solvent adhering to the inner wall of the glass tube is poured into the glass tube. Volatilizes the contained solvent. Finally, by applying a heat treatment to the glass tube, the fluorescent material can be baked onto the inner wall of the glass tube to form a fluorescent film.
[0005]
[Problems to be solved by the invention]
According to the method for manufacturing a cold cathode fluorescent discharge tube described above, if the glass tube has a diameter of 2.0 to 6.0 mmφ and the length of the glass tube is about 350 mm, a thin fluorescent film is formed inside the glass tube. It can be formed well and with good productivity. However, when the diameter of the glass tube is smaller than this, or when the length of the glass tube exceeds 350 mm, the phosphor film cannot be formed satisfactorily. In particular, when a slight bending occurs in the glass tube, it is difficult to form a fluorescent film satisfactorily.
[0006]
For this reason, after discharging | emitting the fluorescent film formation solvent sucked up inside the glass tube from the opening part of a glass tube, it is possible to rotate a glass tube by making the central axis along a tube length direction into a rotating shaft. According to this method, it is expected that problems such as a phosphor film not being satisfactorily formed due to the bending of the glass tube can be improved. However, in this manufacturing method, the following points have not been considered.
[0007]
That is, as the fluorescent film forming solvent, a mixture of a fluorescent material component composed of a solvent, a binder, a red fluorescent material, a green fluorescent material, and a blue fluorescent material is generally used. Specifically, an organic solvent such as nitrocellulose or ethylcellulose is used as the solvent, and a low-melting glass powder is used as the binder. Here, the blue phosphor in the phosphor material component has a smaller specific gravity and a smaller particle diameter than the red phosphor and the green phosphor. For this reason, since the glass tube is centrifuged when the central axis along the tube length direction is rotated as the rotation axis, the red phosphor and the green phosphor contained in the phosphor film forming solvent are contained in the glass tube. Although it collects in the vicinity of the inner wall, the blue phosphor does not collect in the vicinity of the inner wall of the glass tube, but tends to collect on the surface of the fluorescent film forming solvent layer, that is, in a region separated from the inner wall of the glass tube. Thus, when the blue phosphor is concentrated on the surface side of the phosphor film forming solvent layer, the distribution of the red phosphor, the green phosphor and the blue phosphor in the formed phosphor film becomes non-uniform. In addition, when a drying gas is introduced into the glass tube, the blue phosphor selectively flows out, and the red phosphor, the green phosphor and the blue phosphor contained in the formed phosphor film Variations in quantity occur. The blue phosphor has a greater influence on the luminance than the red phosphor and the green phosphor, and is easily deteriorated by ultraviolet rays. Therefore, as described above, when the distribution of the fluorescent material composition in the fluorescent film is non-uniform and the balance of the content is lost, chromaticity and luminance are likely to vary, and the luminance cannot be maintained well over a long period of time. A problem occurs.
[0008]
The present invention has been made to solve the above problems. Accordingly, an object of the present invention is to provide a method for manufacturing a cold cathode fluorescent discharge tube which can easily form a thick fluorescent film having excellent composition and film thickness uniformity. In particular, when the inner diameter of the glass tube is 1.5 mmφ or less, when the length of the glass tube exceeds 350 mm, when the glass tube has a slight bend, and there is a difference in specific gravity between the fluorescent materials in the fluorescent material components. The present invention is to provide a method for producing a cold cathode fluorescent discharge tube which is excellent in the uniformity of composition and film thickness even when it exists, and which has a thick fluorescent film.
[0009]
Another object of the present invention is to provide a method for manufacturing a highly reliable cold cathode fluorescent discharge tube that has little variation in chromaticity and luminance, and that can maintain good luminance over a long period of time.
[0010]
Furthermore, the objective of this invention is providing the manufacturing method of the cold cathode fluorescent discharge tube which can improve productivity.
[0011]
A further object of the present invention is to provide a method of manufacturing a cold cathode fluorescent discharge tube which can realize downsizing of devices such as a liquid crystal monitor and a liquid crystal television.
[0012]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention is characterized by (a) introducing a phosphor film-forming solvent into at least one of the openings into a glass tube having openings at both ends; The step of rotating the glass tube at the first rotation speed with the central axis along the tube length direction as the rotation axis, and attaching the fluorescent film forming solvent to the inner wall of the glass tube, (c) Using the rotation axis, A step of pressing the adhered fluorescent film forming solvent against the inner wall of the glass tube by rotating at a second rotational speed that is higher than the first rotational speed. The gist of the present invention is a method of manufacturing a cold cathode fluorescent discharge tube for forming a film. For example, if the “first rotation speed” is 100 rpm or more and less than 1000 rpm, the “second rotation speed” may be about 5000 rpm or more and less than 15000 rpm. Preferably, the first rotation speed may be 200 rpm or more and less than 500 rpm, and the second rotation speed may be selected to be about 10,000 rpm or more and less than 15000 rpm.
[0013]
In particular, the manufacturing method of the cold cathode fluorescent discharge tube of the present invention, when the inner diameter of the glass tube is 1.5 mmφ or less, when the length of the glass tube exceeds 350 mm, when the glass tube has a delicate bend, In the case where a specific gravity difference exists between the fluorescent materials in the fluorescent material component, this method is suitable for forming a high-quality fluorescent film on the inner wall of the glass tube.
[0014]
In the step of rotating at a relatively low first rotational speed, the centrifugal force is small, and the fluorescent material in the fluorescent film forming solvent is uniformly dispersed and adheres to the inner wall of the glass tube. That is, when the fluorescent film forming solvent includes at least a solvent, a binder, and a plurality of types of fluorescent materials having different specific gravities, a plurality of different specific gravities due to rotation at the first rotational speed with low centrifugal separation ability. Different types of fluorescent material are uniformly dispersed. In this way, the glass tube is rotated at the first rotation speed so that the plurality of types of fluorescent materials in the phosphor film forming solvent are uniformly dispersed in the thickness direction, and then the glass tube is attached to the second glass tube. The fluorescent film-forming solvent, which is rotated at a rotational speed of 5 to increase the centrifugal force and maintains a uniformly dispersed state, is strongly pressed and adhered to the inner wall of the glass tube. Then, after removing the solvent, a fluorescent film having a uniform composition is formed on the inner wall of the glass tube. Further, the step of introducing the fluorescent film forming solvent may be performed by immersing one opening of the glass tube in the fluorescent film forming solvent and sucking the fluorescent film forming solvent from the other opening of the glass tube.
[0015]
As a result, even when the inner diameter of the glass tube is small, a fluorescent film having excellent composition and film thickness uniformity and a thick film can be easily formed on the inner wall of the glass tube. Accordingly, it is possible to form a fluorescent film with little variation in chromaticity and luminance and high strength against ultraviolet irradiation and sputtering, and high luminance can be stably obtained over a long period of time. For this reason, a highly reliable cold cathode fluorescent discharge tube can be manufactured.
[0016]
Furthermore, the viscosity of the fluorescent film forming solvent can be lowered, and the fluorescent film forming solvent can be easily introduced into the glass tube. In particular, if the viscosity of the fluorescent film-forming solvent is lowered, the fluorescent film-forming solvent can be easily sucked into the glass capillary even in a glass capillary having an inner diameter of 1.5 mmφ or less. Therefore, since the process for forming the fluorescent film can be automated and mass production of the cold cathode fluorescent discharge tube can be performed, the production cost and product cost of the cold cathode fluorescent discharge tube can be reduced.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIG. 2, a cold cathode fluorescent discharge tube 1 according to an embodiment of the present invention is formed on a glass tube 2 having both ends sealed and an airtight space inside, and an inner wall of the glass tube 2. Enclosed in the hermetic space of the fluorescent film 3, the discharge electrode 4A and the electrode terminal 5A at the left end of the glass tube 2, the discharge electrode 4B and the electrode terminal 5B at the right end of the glass tube 2, and the glass tube 2 The discharge gas 6 is provided.
[0018]
The glass tube 2 is formed of, for example, an elongated cylindrical thin tube having an outer diameter of 1.9 mmφ, an inner diameter of 1.5 mmφ, and a tube length of 500 mm. The fluorescent film 3 on the inner wall of the glass tube 2 emits visible light upon irradiation with ultraviolet rays generated by discharge. The discharge gas 6 is enclosed to assist the lighting of the cold cathode fluorescent discharge tube 1. For example, a rare gas such as argon (Ar) gas or xenon (Xe) gas can be used as the discharge gas 6, and the pressure inside the glass tube 2 is set to about 5.3 kPa to 13 kPa. The glass tube 2 contains a discharge gas 6 and a certain amount of mercury (mercury particles) necessary for generating mercury discharge.
[0019]
Each of the discharge electrodes 4A and 4B disposed in a pair at both ends inside the glass tube 2 is formed in a cylindrical shape, for example, an electrode material such as nickel (Ni). Each electrode shape of the pair of discharge electrodes 4A and 4B is not particularly limited, but various shapes such as a dish shape, a rod shape, and a wire shape can be adopted.
[0020]
One end of the electrode terminal 5A is electrically connected to the discharge electrode 4A, and the other end is led out of the glass tube 2. Similarly, one end side of the electrode terminal 5B is electrically connected to the discharge electrode 4B, and the other end side is led out of the glass tube 2. Each of the electrode terminals 5A and 5B is made of a metal material having good electrical conductivity such as nickel, for example. Between the electrode terminal 5A and the discharge electrode 4A, between the electrode terminal 5B and the discharge electrode 4B, Both are joined by, for example, melt bonding.
[0021]
Next, a method for manufacturing the cold cathode fluorescent discharge tube 1 shown in FIG. 2 will be described with reference to the process cross-sectional views of FIGS. 1 and 3 to 8.
[0022]
(1) First, as shown in FIG. 3, an elongated cylindrical glass tube 20 having a first opening 21 at one end on the left side and a second opening 22 at the other end on the right side is prepared. To do. This glass tube 20 is obtained by cutting a long glass thin tube having the above outer diameter size and inner diameter size at an appropriate tube length by a known glass cutting technique. At this stage, the fluorescent film 3 is not formed on the inner wall of the glass tube 20.
[0023]
(2) Next, the glass tube 20 is held in an upright state with the first opening 21 of the glass tube 20 on the lower side and the second opening 22 on the upper side, as shown in FIG. And the 1st opening part 21 of this glass tube 20 is immersed in the fluorescent film formation solvent 31 with which the container 30 was filled. As the fluorescent film forming solvent 31, a mixture of three types of components, a solvent, a binder, and a fluorescent material, can be used. As the solvent, for example, an organic solvent such as nitrocellulose or ethylcellulose can be used. As the binder, for example, low melting point glass powder or the like can be used. As the fluorescent material, a commercially available fluorescent material blended with three primary colors of red (R), green (G), and blue (B) having different specific gravities can be used. In the phosphor film forming solvent 31, the content of the solvent in the solution is set to about 11% by weight, for example.
[0024]
(3) Next, the second opening 22 of the glass tube 20 is connected to the suction device 35, and the suction device 35 is operated to make the internal pressure of the glass tube 20 negative. As a result, as shown in FIG. 4, the fluorescent film forming solvent 31 in the container 30 is sucked up from the first opening 21 of the glass tube 20, and the fluorescent film forming solvent 31 is filled into the glass tube 20. If the viscosity of the phosphor film-forming solvent 31 is set low, the glass tube 20 has an inner diameter of 1.5 mmφ, even if the inner diameter of the glass tube 20 is 1.5 mmφ or less. In addition, the phosphor film forming solvent 31 can be sucked up easily and in a good state. The fluorescent film forming solvent 31 adheres evenly over the entire length of the glass tube 20. For the suction device 35, a vacuum exhaust device such as a water flow aspirator, a water seal pump, a steam ejector pump, an oil rotary pump, a dry rotary pump, or a mechanical booster pump can be used.
[0025]
(4) Next, the suction from the second opening 22 of the glass tube 20 is released, and the suction of the fluorescent film forming solvent 31 from the first opening 21 is stopped. The suction by the suction device 35 is released, and excess fluorescent film forming solvent 31 inside the glass tube 20 is discharged from the first opening 21 to the container 30 by its own weight. After the excess fluorescent film forming solvent 31 is discharged, the fluorescent film forming solvent 31 remains attached to the inner wall of the glass tube 20 with a certain thickness.
[0026]
(5) Next, as shown in FIG. 1, the glass tube 20 is attached to the high-speed spinner 7 while being held in an upright state, and the glass tube 20 is moved to a relatively low speed with the central axis along the tube length direction as the rotation axis. Rotate at one rotation speed. The first rotation speed is set to a rotation speed of 100 rpm or more and less than 1000 rpm, preferably 200 rpm or more and less than 500 rpm. By applying this rotation, the fluorescent film-forming solvent is pressed against and adheres to the inner wall of the glass tube 20. However, since the rotational speed is relatively slow, there is no variation in the composition distribution due to the specific gravity difference of the fluorescent material. That is, the red phosphor, the green phosphor, and the blue phosphor in the phosphor film forming solvent are uniformly dispersed by centrifugal force, and are adhering together in the thickness direction of the phosphor film forming solvent. Further, the adhesion strength of the fluorescent film forming solvent to the glass tube is not so strong. On the other hand, when the glass tube 20 is rotated at a rotational speed exceeding 5000 rpm, only the blue phosphor having a small specific gravity is concentrated and distributed on the surface of the phosphor film forming solvent.
[0027]
(6) Next, as shown in FIG. 1, with the glass tube 20 held in an upright state, the glass tube 20 is rotated at a relatively high second rotation speed with the central axis along the tube length direction as the rotation axis. Rotate. The second rotation speed is set to 5000 rpm to 15000 rpm, preferably 10,000 rpm to less than 15000 rpm. By applying this rotation, a strong centrifugal force is applied to the fluorescent film forming solvent 31 adhering to the inner wall of the glass tube, and the fluorescent film forming solvent 31 is strongly pressed against the inner wall of the glass tube 20 and strongly against the inner wall of the glass tube 20. The attached fluorescent film forming solvent 32 can be formed. At this time, by applying a relatively small centrifugal force based on the first rotation speed as described above, the red phosphor, the green phosphor and the blue phosphor in the phosphor film forming solvent 31 are uniformly dispersed. Since the fluorescent film forming solvent 31 adheres in a mixed state in the thickness direction, a relatively large centrifugal force based on the second rotational speed is applied to the fluorescent film forming solvent 31, thereby causing the glass tube 20. Also in the fluorescent film forming solvent 32 strongly adhered to the inner wall, the red phosphor, the green phosphor and the blue phosphor are uniformly dispersed. Therefore, they adhere in a state of being mixed and distributed in the thickness direction of the fluorescent film forming solvent 32.
[0028]
As described above, the red phosphor, the green phosphor and the blue phosphor in the phosphor film forming solvent 32 are attached in a uniformly dispersed state, and a relatively large centrifugal force based on the second rotational speed. As a result, the phosphor film-forming solvent 32 is strongly adhered to the inner wall of the glass tube 20, thereby improving the uniformity of the film thickness and composition of the phosphor film, and variations in chromaticity and luminance are at a level that is not problematic in practice. Can be reduced.
[0029]
(7) Next, as shown in FIG. 5, the second opening 22 of the glass tube 20 is connected to the drying gas generator 8. The drying gas is sent from the drying gas generator 8 into the glass tube 20 to volatilize the solvent contained in the fluorescent film forming solvent 32 attached to the inner wall of the glass tube 20. Examples of the drying gas 80 include dry nitrogen (N ₂ ) Gas, an inert gas such as helium (He), argon (Ar), dry air, or the like can be used. Due to the volatilization of the solvent, the fluorescent film forming solvent 33 having a substantially uniform film thickness can be formed from the fluorescent film forming solvent 32 attached to the inner wall of the glass tube 20.
[0030]
In addition, it is necessary to volatilize the solvent of the fluorescent film formation solvent 33 completely before performing the below-mentioned baking process, and when a solvent remains at the time of a baking process, a void may generate | occur | produce with the volatilization of a solvent. is there. In addition, if the solvent remains during the firing step, the solvent may be oxidized and carbon may be generated in the phosphor film. From this point as well, the solvent in the phosphor film-forming solvent 33 is sufficient before the firing step. It is important to keep it volatilized.
[0031]
(8) Next, as shown in FIG. 6, the glass tube 20 is transferred into a firing furnace (heat treatment furnace) 9. In the baking furnace 9, the glass tube 20 is subjected to heat treatment at about 700 ° C., and the fluorescent material is baked on the inner wall of the glass tube 20 together with the binder in the fluorescent film forming solvent 33. By this baking, the fluorescent film 3 is formed with a uniform film thickness, a dense film quality, and a thick film on the inner wall of the glass tube 20. The fluorescent film 3 is preferably formed with a film thickness of, for example, 10 μm to 20 μm.
[0032]
(9) Next, the discharge electrode 4A and the electrode terminal 5A coupled thereto are arranged in one first opening 21 of the glass tube 20 on which the fluorescent film 3 is formed, and as shown in FIG. One first opening 21 of the glass tube 20 is melt-bonded.
[0033]
(10) Next, after the inside of the glass tube 20 is evacuated from the other second opening 22 of the glass tube 20 by a vacuum exhaust device such as a turbo molecular pump, a cryopump, or an oil diffusion pump, Is filled with the discharge gas 6 at the above pressure. Subsequently, as shown in FIG. 8, the discharge electrode 4 </ b> B and the electrode terminal 5 </ b> B coupled thereto are disposed in the second opening 22 of the glass tube 20. Then, the second opening portion 22 of the glass tube 20 is melt-bonded, and the discharge gas 6 is sealed in the glass tube 20 and the excess glass tube 20 is cut off, whereby the cold cathode fluorescent discharge tube shown in FIG. 1 is completed.
[0034]
In such a manufacturing method of the cold cathode fluorescent discharge tube 1, after introducing the fluorescent film forming solvent 31 into the glass tube 20, first, the glass tube 20 is relatively slow with the central axis along the tube length direction as the rotation axis. Since the rotation is performed at the first rotation speed, the fluorescent materials having different specific gravities in the fluorescent film-forming solvent 31 can be uniformly dispersed by centrifugal force, and the fluorescent film-forming solvent 31 has a plurality of types of fluorescent materials in the thickness direction. Can be adhered to the glass tube 20 in a mixed state. Next, since the glass tube 20 is rotated at a relatively high second rotation speed with the central axis along the tube length direction as the rotation axis, the phosphor film-forming solvent is maintained while the fluorescent material is uniformly dispersed. 31 can be strongly adhered to the inner wall of the glass tube. As a result, even when the inner diameter of the glass tube is small, it is possible to easily form a thick fluorescent film with excellent uniformity of composition and film thickness. Therefore, when the cold cathode fluorescent discharge tube 1 is turned on, a fluorescent film with little variation in chromaticity and luminance and high intensity against ultraviolet irradiation and sputtering can be formed, so that high luminance can be stably obtained over a long period of time. Therefore, the highly reliable cold cathode fluorescent discharge tube 1 can be manufactured.
[0035]
Furthermore, the fluorescent film forming solvent 31 can be easily introduced into the glass tube 20 by lowering the viscosity of the fluorescent film forming solvent 31. In particular, even in a glass tube (glass thin tube) 20 having an inner diameter of 1.5 mmφ or less, the fluorescent film forming solvent 31 can be easily sucked into the glass tube 20. Therefore, the process for forming the fluorescent film 3 can be automated and the cold cathode fluorescent discharge tube 1 can be mass-produced, so that the production cost and product cost of the cold cathode fluorescent discharge tube 1 can be reduced.
[0036]
Further, in such a manufacturing method of the cold cathode fluorescent discharge tube 1, a high-quality fluorescent film 3 can be formed on the inner wall of the glass tube 2 having an inner diameter of 1.5 mmφ or less. Miniaturization of a device such as a television can be realized.
[0037]
(Other embodiments)
Although the present invention has been described with reference to the above embodiment, it should not be understood that the description and the drawings, which form a part of this disclosure, limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.
[0038]
For example, in FIG. 4, a method is adopted in which the glass tube 20 is held upright, the fluorescent film forming solvent 31 is sucked up, and the fluorescent film forming solvent 31 is introduced into the inner wall of the glass tube 20. However, in the present invention, the glass tube 20 is disposed in a horizontal state, that is, in a state in which the glass tube 20 is laid down horizontally, the internal pressure of the glass tube 20 is set to a negative pressure, and the fluorescent film forming solvent 31 is placed in the glass tube 20 from the lateral direction. It may be introduced. Thereafter, the suction from the second opening 22 of the glass tube 20 is released, the glass tube 20 is brought into an upright state, and the excess fluorescent film forming solvent 31 inside the glass tube 20 is removed by its own weight. The container 30 may be discharged from the container. Thereafter, as in FIG. 1, the glass tube 20 is attached to the high-speed spinner 7 while being held in an upright state, and the glass tube 20 is rotated at a relatively low speed with the central axis along the tube length direction as the rotation axis. Rotate at speed.
[0039]
Moreover, in FIG. 1, after applying the fluorescent film forming solvent 31 to the glass tube 20, a method of rotating the glass tube 20 while holding it upright is adopted. However, the present invention is in an upright state depending on the purpose and application. It may be rotated with the rotating shaft held at any angle including the horizontal state. Further, the rotation axis may be moved by a certain angle during the rotation process at the first rotation speed and the rotation process at the second rotation speed.
[0040]
Furthermore, in the manufacturing method of the cold cathode fluorescent discharge tube 1 according to the embodiment of the present invention, after the fluorescent film forming solvent 31 is applied to the glass tube 20, the glass tube 20 is moved to the first rotation speed and the second rotation speed. Although the method of rotating twice at the rotational speed is adopted, the present invention includes a step of rotating at least 3 degrees using the third rotational speed, the fourth rotational speed,... You may have, and you may change each rotational speed.
[0041]
Furthermore, in the manufacturing method of the cold cathode fluorescent discharge tube 1 according to the embodiment of the present invention, after introducing the fluorescent film forming solvent 31 into the glass tube 20, the glass tube 20 is subjected to the first rotation speed. In the present invention, the glass tube 20 may be rotated at the first rotation speed simultaneously with the step of introducing the fluorescent film forming solvent 31 into the glass tube 20.
[0042]
Furthermore, in the manufacturing method of the cold cathode fluorescent discharge tube 1 according to the embodiment of the present invention, the fluorescent film forming solvent 31 is introduced into the glass tube 20, and the glass tube 20 is rotated at the second rotation speed. , The drying gas 80 is fed into the glass tube 20 to form a fluorescent film forming solvent 33 having a uniform film thickness. However, the present invention provides a fluorescent film forming solvent in the glass tube 20. 31 is introduced, a drying gas 80 is fed into the glass tube 20 to form a fluorescent film forming solvent 33 having a uniform film thickness, and then the glass tube 20 is rotated at a second rotational speed. Good. Alternatively, rotation at the second rotation speed may be given while flowing the drying gas 80 into the glass tube 20.
[0043]
Furthermore, in the manufacturing method of the cold cathode fluorescent discharge tube 1 according to the embodiment of the present invention, a method of completing the cold cathode fluorescent discharge tube 1 in 10 steps from the step (1) to the step (10) is adopted. However, according to the present invention, the cold cathode fluorescent lamp 1 is completed by repeating the steps (2) to (6) or the steps (2) to (8) a plurality of times depending on the purpose and application. You may let them.
[0044]
Further, for example, the present invention can be applied to a double tube type discharge tube in which a glass tube is further provided on the outer periphery of the cold cathode fluorescent discharge tube 1.
[0045]
As described above, the present invention naturally includes various embodiments not described herein. Accordingly, the technical scope of the present invention is defined only by the invention-specific matters according to the above-mentioned reasonable claims.
[0046]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the cold cathode fluorescent discharge tube which is excellent in a composition and the uniformity of a film thickness, and can form a thick fluorescent film easily can be provided. In particular, when the inner diameter of the glass tube is 1.5 mmφ or less, when the length of the glass tube exceeds 350 mm, when the glass tube has a slight bend, and there is a difference in specific gravity between the fluorescent materials in the fluorescent material components. Even when it exists, it is possible to provide a cold cathode fluorescent discharge tube having a fluorescent film that is thick and excellent in composition and film thickness uniformity.
[0047]
In addition, according to the present invention, it is possible to provide a method for manufacturing a highly reliable cold cathode fluorescent discharge tube that has little variation in chromaticity and luminance, and that can maintain good luminance over a long period of time.
[0048]
Furthermore, according to this invention, the manufacturing method of the cold cathode fluorescent discharge tube which can improve productivity can be provided.
[0049]
Furthermore, according to the present invention, it is possible to provide a method of manufacturing a cold cathode fluorescent discharge tube that can realize downsizing of devices such as a liquid crystal monitor and a liquid crystal television.
[Brief description of the drawings]
1 is a process cross-sectional view of a cold cathode fluorescent discharge tube according to an embodiment of the present invention, and is a process cross-sectional view subsequent to FIG.
FIG. 2 is a cross-sectional structure diagram of a cold cathode fluorescent discharge tube according to an embodiment of the present invention.
FIG. 3 is an initial process cross-sectional view of a cold cathode fluorescent discharge tube according to an embodiment of the present invention.
4 is a process sectional view of the cold cathode fluorescent discharge tube following FIG. 3 according to the embodiment of the present invention. FIG.
FIG. 5 is a process cross-sectional view of the cold cathode fluorescent discharge tube following FIG. 1 according to the embodiment of the present invention.
6 is a process sectional view of the cold cathode fluorescent discharge tube following FIG. 5 according to the embodiment of the present invention. FIG.
7 is a process cross-sectional view of the cold cathode fluorescent discharge tube following FIG. 6 according to the embodiment of the present invention. FIG.
8 is a process sectional view of the cold cathode fluorescent discharge tube following FIG. 7 according to the embodiment of the present invention. FIG.
[Explanation of symbols]
1 Cold cathode fluorescent discharge tube
2,20 glass tube
3 Fluorescent film
4A, 4B Discharge electrode
5A, 5B electrode terminal
6 Discharge gas
7 High-speed spinner
8 Drying gas generator
9 Firing furnace
21 First opening
22 Second opening
30 containers
31, 32, 33 Phosphor film forming solvent
35 Suction device
80 Drying gas

Claims (2)

Introducing a fluorescent film forming solvent containing a plurality of types of fluorescent materials having different specific gravities from at least one of the openings into a glass tube having openings at both ends;
Using the central axis along the tube length direction of the glass tube as a rotation axis, the glass tube is rotated at a first rotation speed with a low centrifugal separation ability for a plurality of types of fluorescent materials having different specific gravities of 100 rpm to 1000 rpm. A step of uniformly dispersing the plurality of types of fluorescent materials on the inner wall of the glass tube;
After uniformly dispersing the plural types of fluorescent materials on the inner wall of the glass tube, the glass tube is rotated at a second rotation speed higher than the first rotation speed using the rotation shaft. And pressing the plurality of types of fluorescent materials uniformly dispersed against the inner wall of the glass tube, and forming a fluorescent film made of the plurality of types of fluorescent material on the inner wall of the glass tube from the fluorescent film forming solvent. A method of manufacturing a cold cathode fluorescent discharge tube, comprising: forming a cold cathode fluorescent discharge tube. The plurality of types of fluorescent materials include a blue phosphor, and a red phosphor and a green phosphor having a specific gravity larger than that of the blue phosphor and a larger particle diameter. Of manufacturing a cold cathode fluorescent discharge tube.

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