JP2002231133A - Method of manufacturing cold cathode fluorescent lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a cold cathode fluorescent lamp capable of eliminating a variation in chromaticity between products and between cold cathode fluorescent lamps in axial direction. SOLUTION: The components of a fluorescent substance formed by mixing red R, green G, and blue B fluorescent substances with each other and organic solvent SV are adjusted, and the adjusted substance and solvent are agitated in a dry atmosphere to manufacture fluorescent substance suspension. The manufactured fluorescent substance suspension is applied onto the inside wall surface of a glass tube, and the inside wall surface is dried.

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 in which the chromaticity change of a phosphor film over time is suppressed, and more particularly to a method of manufacturing a cold cathode fluorescent lamp suitable for use as an illumination light source of a liquid crystal display device. About.

[0002]

2. Description of the Related Art In a liquid crystal display device, an illumination light source (so-called backlight) for illuminating the liquid crystal panel in order to observe an electronic latent image formed on the liquid crystal panel as a clear visible image.
Some are equipped with.

In this type of backlight, a side edge type in which a linear lamp is disposed on a side surface of a transparent plate formed of an acrylic resin or the like called a light guide plate, and a linear lamp is disposed just below the back of a liquid crystal panel. The direct type is known.

[0004] Notebook computers which require a thinner type employ a side-edge type, and many liquid crystal display devices for display monitors use a side-edge type in order to reduce the depth.

However, in a large-sized liquid crystal display device such as a display monitor, it is an essential requirement that a bright color display image with high contrast be obtained and that the luminance does not decrease even after long-term use. A liquid crystal display device in which a lamp (linear lamp) is installed directly below a liquid crystal panel has been commercialized.

FIG. 8 is a schematic sectional view for explaining a configuration example of a liquid crystal display device having a direct-type backlight. In FIG. 8, a PNL is a liquid crystal panel that generates an image electronically. A liquid crystal panel LC is sandwiched between a pair of glass substrates SUB1 and SUB2, and a pixel selection formed on one or both of the glass substrates SUB1 and SUB2. An image is generated by selectively applying a voltage to the electrodes for use.

[0007] Deflection plates PL1 and PL2 are laminated on the outer surfaces of the glass substrates SUB1 and SUB2, respectively, and the polarization direction of the illumination light from the backlight is controlled so that the light passing through the liquid crystal layer LC is directed to the upper side. The light is emitted from the polarizing plate (PL2) or blocked.

The backlight BL comprises a plurality of cold cathode fluorescent lamps CFL and a reflector REF, and a diffuser SC for controlling the distribution of illumination light emitted from the cold cathode fluorescent lamp CFL.
T and prism sheet P for controlling the direction of the illumination light
It is installed on the back of the liquid crystal panel PNL via the RS.

Japanese Unexamined Patent Publication No. Sho 51-13666 and Japanese Unexamined Patent Publication No. Sho 63-163 discloses such prior art.
309921 and the like.

[0010]

A large-screen display is possible.
In a liquid crystal display device provided with a direct-type backlight which needs to maintain brightness even when used for a long period of time, a plurality of cold cathode fluorescent lamps are usually arranged.

A cold cathode fluorescent lamp is a so-called low-pressure mercury lamp, in which a phosphor film is applied to the inner wall of a tubular glass tube, and the phosphor film is excited by ultraviolet rays generated by evaporation of the enclosed mercury to emit visible light. Is what you do.

In recent cold-cathode fluorescent lamps, red, green, and blue fluorescent materials are mixed as a phosphor film to obtain a wide-band visible light.

FIG. 9 is a schematic view for schematically explaining a conventional method of agitating a phosphor suspension and applying a phosphor suspension to the inner wall of a glass tube constituting a cold cathode fluorescent lamp. . In the figure, CTN is a container of the phosphor suspension PPC,
A stirrer PST for stirring and suspending the fluorescent substance and the organic solvent is provided.

The phosphor suspension PPC has red, green and
Blue fluorescent substance suspended in organic solvent at a specified ratio
Examples of red, green and blue fluorescent substances
For example, Y_TwoO_Three: Eu³⁺, LaPO_Four: Ce³⁺, Tb³⁺,
BaMg_TwoAl₁₆O₂₇: Eu ²⁺Is used. The fluorescent material is
As a combination of "phosphor crystal: activator (activator)"
Notation. In addition, butyl acetate and xylene are used as organic solvents.
General.

This fluorescent substance is put into a container CTN together with an organic solvent, a binder (for example, the main component is Al ₂ O ₃ ) and an adhesive (for example, nitrocellulose), and is stirred by driving a stirrer PST. Creates a phosphor suspension uniformly dispersed in an organic solvent. The container CTN at the time of stirring is placed in the air, and the stored fluorescent substance and organic solvent are stirred while being in contact with the air.

One or a plurality of glass tubes CFL-T serving as a cold cathode fluorescent lamp are bundled in the phosphor suspension PPC, and the bundle is immersed as shown by arrow A with its axial direction vertical, and then as shown by arrow B. To raise. At this time, the glass tube CFL-T
A phosphor film having a predetermined thickness is applied to the inner wall of the glass tube CFL-T while the phosphor suspension PPC flows down the inner wall of the glass tube. By subjecting this to a baking process, a glass tube CFL-T having a phosphor film on the inner wall can be obtained.

The above-mentioned uniform application of the phosphor suspension is adjusted by the flow rate of the phosphor suspension flowing down the inner wall of the glass tube CFL-T. The flow rate is controlled by adjusting the particle size distribution of the fluorescent substance, adjusting the particle shape, adjusting the method of dispersing in the organic solvent (hard dispersion, soft dispersion), and adjusting the dispersant addition amount.

Thereafter, one electrode is attached to one end of a glass tube CFL-T having a phosphor film on the inner wall, a predetermined amount of mercury particles is charged, and the other electrode is attached to the other end. Then, the cold cathode fluorescent lamp is completed by vacuum sealing.

Since the inside diameter of the above-mentioned glass tube CFL-T is extremely small, the glass tube CFL-T depends on the viscosity of the phosphor suspension PPC and the particle size of the fluorescent substance.
In some cases, the phosphor suspension PPC is difficult to enter into T. In such a case, a low-pressure suction device is provided at the upper end in the vertical direction of the glass tube CFL-T, and the phosphor suspension PPC is forcibly sucked into the glass tube CFL-T. The phosphor film is applied under natural flow.

In the conventional phosphor suspension stirring method,
The phosphor and the organic solvent are agitated while being in contact with the air. Chromaticity values (x, y) on the CIE chromaticity diagram of the entire tube of the cold cathode fluorescent lamp using the phosphor suspension stirred by this method
Changes with the lapse of time after stirring and mixing of the phosphor suspension to be applied, and the glass tube CFL of the cold cathode fluorescent lamp is changed.
The chromaticity value changes even above and below −T.

That is, in the cold cathode fluorescent lamp using the phosphor suspension immediately after the stirring adjustment and the cold cathode fluorescent lamp using the phosphor suspension left for a certain period of time, the entire color of the cold cathode fluorescent lamp is used. A deviation (deviation) occurs in the degree value.

Conventionally, after adjusting the agitation, the ratio of the phosphor is adjusted again to cope with the problem, and when the adjustment becomes impossible, it is disposed of. In addition, the upper side (the upper side when applying the phosphor suspension) and the lower side (the same, the lower side) of the same cold cathode fluorescent lamp
Causes a deviation in the chromaticity value. This phenomenon was unknown.

For this reason, when a backlight using the cold cathode fluorescent lamp is incorporated in a liquid crystal display device, display colors vary. Solving this has been one of the problems to be solved in the technical field of liquid crystal display devices.

Further, a phosphor, particularly a blue phosphor (BaMg)
₂ Al ₁₆ O ₂₇ : Eu ²⁺ ) is liable to be oxidized in the baking treatment, which causes a decrease in luminance. The baking process is performed to remove organic substances remaining in the applied phosphor suspension,
This baking temperature is a high temperature treatment of 400 to 600 ° C.

For this reason, resolving the reduction in luminance due to baking has been another problem to be solved in the technical field.

An object of the present invention is to solve the above-mentioned problems and eliminate the chromaticity deviation of each product and the chromaticity deviation of each cold-cathode fluorescent lamp in the axial direction, thereby avoiding a decrease in luminance due to baking processing. It is another object of the present invention to provide a cold cathode fluorescent lamp manufacturing method.

[0027]

According to the study of the present inventors, it has been found that the aforementioned chromaticity deviation is caused by the adjustment condition of the phosphor suspension. That is, in the prior art, the phosphor suspension is adjusted in an atmosphere in which the air is in contact with 60% humidity air. During the stirring process, water in the air is mixed, and this water causes a chromaticity deviation. It turned out to be.

Based on this fact, the present invention adjusts the stirring of the fluorescent substance (usually, red, green and blue phosphors) and the organic solvent in a dry atmosphere or when the phosphor suspension comes into contact with air. In this case, a method of performing a stirring process under conditions not to be used is adopted. The typical configurations of the present invention are as follows.

That is, a phosphor suspension comprising a phosphor and an organic solvent is stirred in a dry atmosphere, and the stirred phosphor suspension is applied to the inner wall of a tube.

The phosphor suspension is applied to a cold-cathode fluorescent lamp placed in a dry atmosphere, and the inner wall of the tube is exposed to the dry atmosphere to be applied to the inner wall.

The suspension is stirred in an inert gas atmosphere having a specific gravity higher than that of air, and the stirred phosphor suspension is applied to the inner wall of the tube.

An inert gas having a specific gravity higher than that of air is interposed between the surface of the suspension and the air to stir the phosphor suspension composed of the fluorescent substance and the organic solvent. Apply to inner wall of tube.

By adopting such a method, the chromaticity value of the whole cold cathode fluorescent lamp can be determined by using the phosphor suspension immediately after stirring and the phosphor suspension after a certain time after stirring. The chromaticity deviation did not occur between the chromaticity deviations and those using. Also, no chromaticity deviation in the axial direction of the same cold cathode fluorescent lamp was observed.

According to the present invention, a cold cathode fluorescent lamp having the same chromaticity value between products and in the axial direction can be obtained by using a phosphor suspension which is only stirred after a predetermined time has elapsed after stirring. it can.

After baking the tube coated with the phosphor suspension, it is left in a nitrogen atmosphere at a temperature substantially equal to the baking temperature for a predetermined time.

By leaving in a nitrogen atmosphere after the baking treatment, the phosphor is reduced, and a decrease in luminance can be avoided.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to examples.

FIG. 1 is an explanatory view of a method for manufacturing a cold cathode fluorescent lamp according to the present invention. After adjusting the components of the fluorescent material and the organic solvent, which are a mixture of the red, green, and blue phosphors, the mixture is stirred in a dry atmosphere to prepare a phosphor suspension. The phosphor suspension thus prepared was applied to the inner wall of a glass tube constituting a cold cathode fluorescent lamp,
Baking. This baking process is a series of baking processes in which baking is performed in air after pre-baking in a nitrogen atmosphere.

After the baking treatment, the wafer is again left in a nitrogen atmosphere at a temperature of 600 ° C. for 10 minutes. When left at a high temperature in this nitrogen atmosphere, the phosphor (particularly, the blue phosphor) undergoes a reducing action, and is restored to the original component configuration.

The above-mentioned dry atmosphere means an atmosphere in which moisture does not enter the suspension of the adjusted fluorescent substance and the organic solvent, and has a low humidity (for example, a dew point of −22 ° C.).
C) High pressure air, low humidity (for example, dew point -70 ° C) in nitrogen gas, and low temperature (for example, dew point -64 ° C) in oxygen gas.

Further, by inserting an inert gas (for example, argon gas) having a specific gravity higher than that of air between the surface of the suspension and air, an atmosphere in which the suspension does not come into contact with air can be created. .

Further, by adding a water absorbing material such as silica gel to the suspension and stirring the water, the water remaining in the suspension can be removed.

FIG. 2 is a schematic diagram illustrating a first example of a manufacturing apparatus for implementing the method of manufacturing a cold cathode fluorescent lamp according to the present invention. In the figure, CTN is a container of a phosphor suspension PPC, and has a stirrer PST for stirring and suspending a fluorescent substance and an organic solvent. CHM is an outer container that shields the container CTN of the phosphor suspension PPC from the outside world, and includes a gas introduction pipe CSTI having a valve and a gas discharge pipe CSTO.
It has. Other configurations are the same as those in FIG.

In this manufacturing apparatus, the container CTN of the phosphor suspension PPC is surrounded by the outer container CHM, and the gas introduction pipe CST
Either high pressure air with a dew point of −22 ° C., nitrogen gas with a dew point of −70 ° C., or oxygen gas with a dew point of −64 ° C.
Alternatively, a phosphor suspension PP is introduced by introducing a mixed gas thereof.
Shield C from air. In this state, the stirring device PST is driven to produce a phosphor suspension PPC. The above gas may be discharged from the gas discharge pipe CSTO and circulated.

The phosphor suspension PPC is applied to the inner wall of the glass tube CFL-T in the same manner as in FIG. 9 and baked. After the baking treatment, the substrate is allowed to stand in a nitrogen atmosphere at approximately 600 ° C., which is close to the temperature of the baking treatment, for 10 minutes.

Thereafter, the electrodes are attached, mercury is enclosed, and vacuum sealing is performed to complete a cold cathode fluorescent lamp.

According to this method, there is no deviation in the overall chromaticity value, no chromaticity deviation in the axial direction of the same cold-cathode fluorescent lamp, and no reduction in the luminance of the phosphor. A fluorescent lamp can be obtained.

FIG. 3 is a schematic diagram illustrating a second example of a manufacturing apparatus for performing the method of manufacturing a cold cathode fluorescent lamp according to the present invention. In the figure, CSTI denotes an inert gas introduction pipe, NGS denotes an inert gas layer, and the same reference numerals as those in FIG. 2 correspond to the same parts.

In this cold cathode fluorescent lamp manufacturing apparatus, the introduction tube CSTI is placed on the liquid surface of the mixture of the fluorescent substance and the organic solvent (phosphor suspension PPC) charged in the phosphor suspension PPC container CTN. , An argon gas is introduced as an inert gas having a specific gravity greater than that of air to form an inert gas layer NGS. In this state, the stirrer PST is driven.

The inert gas layer NGS is a phosphor suspension PP
C is blocked from the air layer and the phosphor suspension PPC is stirred.
Has a function of keeping a dry atmosphere.

The stirred phosphor suspension PPC is placed in a glass tube C
It is applied to the inner wall of FL-T and baked. After the baking treatment, the substrate is allowed to stand in a nitrogen atmosphere at approximately 600 ° C. close to the temperature of the baking treatment for 10 minutes.

Thereafter, the electrodes are attached, mercury is sealed, and vacuum sealing is performed to complete a cold cathode fluorescent lamp.

According to this method as well, no deviation occurs in the overall chromaticity value, no chromaticity deviation occurs in the axial direction of the same cold cathode fluorescent lamp, and the coldness does not decrease the luminance of the phosphor. A cathode fluorescent lamp can be obtained.

The phosphor suspension is applied to the inner wall of the tube, baked, and then left in a nitrogen atmosphere as follows.

In order to prevent the glass tube coated with the phosphor suspension from being deformed, the glass tube is placed in a stainless steel pipe and placed in a nitrogen atmosphere furnace at 600 ° C. A small hole is made on one side of the furnace to allow nitrogen to escape.
The flow rate of nitrogen is, for example, 3500 liters / hour.
At this time, the inner volume of the furnace is about 0.3 mm ² .

After being left at about 600 ° C. for 10 minutes, it is cooled to about 400 ° C. to prevent oxidation, taken out of the furnace, and cooled to room temperature.

As for the cold cathode fluorescent lamp adopting the process of leaving in a nitrogen atmosphere after the above-mentioned baking treatment, a life test after 500 hours showed that the cold cathode fluorescent lamp not subjected to the leaving treatment in a nitrogen atmosphere was subjected to a life test. While the luminance maintenance ratio was 93.8%, the decrease in luminance was reduced to 97.54%.

Further, when the luminance maintenance ratio with respect to (time) ^1/2 was examined, the estimated life at a luminance maintenance ratio of 50% was 237000 hours after passing through a process of leaving in a nitrogen atmosphere after baking treatment. Without this process, it took 32,000 hours.

Next, a configuration example of a liquid crystal display device incorporating a cold cathode fluorescent lamp manufactured according to the present invention as a backlight will be described.

FIG. 4 is an exploded perspective view illustrating the structure of a backlight for a liquid crystal display device using a cold cathode fluorescent lamp according to the present invention. Lower frame FLM generally made of metal material
A plurality of cold cathode fluorescent lamps CFL are arranged on the upper surface of -D so that the longitudinal directions thereof are parallel to each other, and the upper frame FLM-U is put thereon, and the two are united by claws NL. Resin mold MLD-L (left mold), M
The upper frame FLM-U and the lower frame FLM-D are sandwiched and integrated by an LD-R (right mold). The surface on the CFL side of the lower frame FLM-D has a function of a reflector. Another member such as a sheet having a reflection function may be interposed between the lower frame FLM-D and the CFL.

Then, two light diffusion plates (diffusion sheets) SCT and at least one prism sheet PRS are stacked on the upper frame FLM-U to constitute a direct-type backlight. A liquid crystal panel (not shown) is placed above the backlight, and a power supply for driving the CFL, other necessary circuits, and structural members are mounted.

It should be noted that among the plurality of linear light sources CFL disposed on the upper surface of the lower frame FLM-D, the mounting positions of the linear light sources CFL-E located at both ends are higher than the arrangement surface level of the other linear light sources CFL. It is shifted by a distance H toward the diffusion plate SCT side, that is, the liquid crystal panel side, to suppress a decrease in luminance at the end.

FIG. 5 is a sectional view of an essential part taken along line DD of FIG. 4 for explaining an example of a specific structure of the backlight shown in FIG. In FIG. 5, after fixing a plurality of linear light sources CFL on the inner surface of the lower frame FLM, the lower frame FLM-
D and the upper frame FLM-U are attached to each other, and both are fixed at predetermined positions with claws NL.
-L, MLD-R.

Then, the diffusion plate SCT and the prism sheet PRS are placed on the upper surface of the upper frame FLM-U, and the screws BT
It is fixed and configured.

FIG. 6 is a developed perspective view for explaining another example of a backlight configuration for a liquid crystal display device using the cold cathode fluorescent lamp according to the present invention. One end of a power supply line (cable) ESP is attached to each end of the cold cathode fluorescent lamp CFL, and is covered with a rubber cushion (rubber bush) GB fitted on each power supply line.

A connector CO is connected to the other end of the power supply line ESP.
N is attached. The connector CON has a structure for receiving a pair of power supply lines ESP adjacent to each other, but the power supply lines are separated inside the connector.

The connector CON arranged on the right side of FIG. 6 is a lower frame FLM-D made of a metal material such as aluminum.
Is connected to an inverter circuit INV mounted on a circuit board mounted on the lower surface of the inverter. In FIG. 6, the circuit board on which the inverter circuit is mounted is indicated by INV, but hereinafter, the inverter circuit itself will be described as INV.

An inverter circuit INV is individually provided for each of the cold cathode fluorescent lamps CFL, and this circuit and the high voltage application side (also called the hot side) of the linear light source CFL, as shown in FIG.
Are positioned so that the wiring length between them does not vary for each linear light source.

The linear light source CFL is supplied from the inverter circuit INV.
The voltage supplied to the (cold-cathode tube) receives a loss according to the length of the power supply line ESP, and a variation in luminance occurs between the plurality of linear light sources CFL. Making the wiring length of each power supply line ESP uniform is effective in preventing image deterioration of the liquid crystal panel due to this luminance variation, and a plurality of inverter circuits INV are arranged in parallel on the right side of the lower frame FLM-D. The layout to be arranged is one of the means.

The insulating sheet I is provided between the lower surface of the lower frame FLM-D and the circuit board on which the inverter circuit INV is mounted.
NS (registered trademark) is arranged, and the inverter circuit INV
The (circuit board) is attached to the cover ICOV, and is attached to the lower frame FLM-D via the insulating sheet INS.

The lower frame F is provided on the lower surface of the insulating sheet INS.
A connector board CSUB extending along the left side of the LM-D is provided. In FIG. 6, the connector CON that receives the power supply line ESP connected to the left side of each linear light source CFL is connected to the terminal of the connector board CSUB. Connector board CSU
One terminal of a connector CON formed at both ends of the power supply line ESP is connected to another terminal of B, and the other terminal is connected to a low voltage side (reference potential side) terminal of the inverter circuit INV. In such connection, each linear light source CFL in FIG.
A reference potential is applied to the left electrode (also called the low voltage side, Cold side).

In the backlight shown in FIG.
The structure is such that the CT and the prism sheet PRS are sandwiched and fixed between an upper frame FLM-U made of a metal preferably made of aluminum and a right mold MLD-R and a left mold MLD-L made of a synthetic resin or the like.

In such a structure, an unexpected mechanical shock or thermal shock caused by the upper surface of the upper frame FLM-U made of metal coming into contact with the lower surface of the liquid crystal panel, that is, the main surface of the substrate made of glass or the like, is not affected. Joins the bottom of the LCD panel,
The substrate may be damaged. To prevent this, a rubber spacer GS is provided on the upper surface of the upper frame FLM-U along the opening of the upper frame FLM-U.

Each of the diffuser plate SCT and the prism sheet PRS has the ends thereof at the lower surface of the upper frame FLM-U, the right mold MLD-R and the left mold MLD in a state where the direct type backlight shown in FIG. 6 is assembled. −L have such a size that they respectively overlap with the upper surface.

On the other hand, the upper frame FLM-U, the right mold MLD-R and the left mold MLD-L
Since they are combined by LT, a recess HOL is formed at each end of the diffusion plate and the prism sheet to avoid these screws. By providing this recess HOL not at the corner of the diffusion plate or the prism sheet but at the corner, it is gripped by the upper frame FLM-U, the right mold MLD-R and the left mold MLD-L, and is not affected by mechanical vibration. It is hard to slip. In addition, problems such as scattering of transmitted light in the periphery can be solved by gripping the ends.

The direct type backlight shown in FIG. 6 has an upper mold MLD-U and a lower mold MLD-D. These upper mold MLD-U and lower mold M
The upper surface of each of the LD-D extends in the direction intersecting the extending direction of the right mold MLD-R and the left mold MLD-L on the lower surface of the diffusion plate SCT and is opposed to the peripheral portions (upper side, lower side in FIG. 6), respectively. It is arranged so that it may touch. Therefore, the upper mold MLD-U and the lower mold MLD-
D, the right mold M on the lower surface of the diffusion plate SCT
They are arranged apart from each other in a region between the LD-R and the left mold MLD-L.

While both the right mold MLD-R and the left mold MLD-L have shapes facing the lower surface and side surfaces of the periphery of the diffusion plate or prism sheet, the upper mold MLD-U and the lower mold MLD -D
Faces only the lower surface of its periphery. In other words, the upper mold MLD-U and the lower mold MLD-D can reduce the area in the main surface of the liquid crystal panel because there is no portion facing the side surface of the optical sheet. It is suitable for a so-called narrow frame of the device.

Further, since the lower portion (lower surface) of each of the upper mold MLD-U and the lower mold MLD-D is supported by the upper surface of the lower frame FLM-D, the stability of the entire direct-type backlight increases. . Thus, the direct-type backlight structure shown in FIG. 6 is suitable for reducing the thickness of the liquid crystal display device.

FIG. 7 is an external view showing an example of a display monitor equipped with a liquid crystal display device equipped with a backlight using a cold cathode fluorescent lamp according to the present invention. The backlight constituting the liquid crystal display device mounted on the screen of the monitor, that is, the display section has the configuration of the embodiment of the present invention described above.

The backlight using the cold cathode fluorescent lamp according to the present invention is not limited to a display monitor using a direct type backlight as described above, but a display monitor using a so-called side edge type backlight. The present invention can be similarly applied to a monitor of a desktop personal computer or a backlight of a liquid crystal display device for a display device of a notebook personal computer, a television receiver, and other devices.

[0081]

As described above, according to the present invention,
There is no deviation in the overall chromaticity value between the one using the phosphor suspension immediately after stirring and the one using the phosphor suspension after a certain time after stirring, and the chromaticity in the axial direction. A cold cathode fluorescent lamp without deviation can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a method for manufacturing a cold cathode fluorescent lamp according to the present invention.

FIG. 2 is a schematic diagram illustrating a first example of a manufacturing apparatus for performing a method of manufacturing a cold cathode fluorescent lamp according to the present invention.

FIG. 3 is a schematic diagram illustrating a second example of a manufacturing apparatus for performing the method of manufacturing a cold cathode fluorescent lamp according to the present invention.

FIG. 4 is an exploded perspective view illustrating a backlight configuration for a liquid crystal display device using the cold cathode fluorescent lamp according to the present invention.

FIG. 5 is a cross-sectional view of a principal part along line DD of FIG. 4 for explaining an example of a specific structure of the backlight shown in FIG. 4;

FIG. 6 is an exploded perspective view illustrating another example of a backlight configuration for a liquid crystal display device using the cold cathode fluorescent lamp according to the present invention.

FIG. 7 is an external view showing an example of a display monitor equipped with a liquid crystal display device provided with a backlight using a cold cathode fluorescent lamp according to the present invention.

FIG. 8 is a schematic cross-sectional view illustrating a configuration example of a liquid crystal display device including a direct-type backlight.

FIG. 9 is a schematic diagram for schematically explaining a conventional method of applying a phosphor suspension to an inner wall of a glass tube constituting a cold cathode fluorescent lamp, and a method of agitating a phosphor suspension.

[Explanation of symbols]

 CTN Phosphor suspension PPC container PST stirrer PPC phosphor suspension CFL-T Glass tube to be a cold cathode fluorescent lamp CHM container Outer container for shielding CTN from the outside CSTI Gas inlet tube CSTO Gas discharge tube.

Continuing from the front page (72) Inventor Yoshinobu Shiratori 3350 Hayano, Mobara City, Chiba Prefecture Within Hitachi Electron Devices, Ltd. F-term (reference) 2H091 FA21Z FA32Z FA42Z LA02 LA15 LA18 5C028 EE02

Claims (6)

[Claims] 1. A phosphor suspension comprising a phosphor and an organic solvent is stirred in a dry atmosphere, and the stirred phosphor suspension is applied to the inner wall of a tube of a cold cathode fluorescent lamp. Of manufacturing a cold cathode fluorescent lamp. 2. A method of manufacturing a cold cathode fluorescent lamp, comprising applying a phosphor suspension to an inner wall of a tube of the cold cathode fluorescent lamp in a dry atmosphere. 3. The phosphor suspension is agitated in an inert gas atmosphere having a specific gravity higher than that of air, and the agitated phosphor suspension is applied to an inner wall of a tube of a cold cathode fluorescent lamp. Of manufacturing a cold cathode fluorescent lamp. 4. A phosphor suspension comprising a phosphor and an organic solvent, which is agitated by interposing an inert gas having a specific gravity higher than air between the surface and air, and stirring the phosphor suspension. Is applied to the inner wall of the tube of the cold cathode fluorescent lamp. 5. The method according to claim 1, wherein the fluorescent substance is a red, green, or blue fluorescent substance.
The method for producing a cold cathode fluorescent lamp according to any one of the above. 6. The method according to claim 1, wherein after baking the tube coated with the phosphor suspension, the tube is left in a nitrogen atmosphere at a temperature substantially equal to the baking temperature for a predetermined time. 5. The method for producing a cold cathode fluorescent lamp according to 3 or 4.