JP4549360B2 - Fluorescent lamp manufacturing method and fluorescent lamp glass tube manufacturing method - Google Patents

Description

  The present invention relates to a fluorescent lamp manufacturing method, a fluorescent lamp glass tube manufacturing method, and a fluorescent lamp.

Generally, a fluorescent lamp has a coating process for applying a phosphor suspension in a glass tube, a drying process for drying the phosphor suspension, and a forming process for firing the dried phosphor suspension to form a phosphor layer. It is manufactured through a process such as a sealing process in which electrodes are sealed at both ends of the glass tube (Patent Document 1).
In recent years, with the downsizing of fluorescent lamps, glass tubes with a small diameter have been used. However, when the glass tube becomes small in diameter, even if the glass tube is slightly bent, uneven application of the phosphor suspension occurs in the coating process. End up. Therefore, when using a small-diameter glass tube, a correction process is performed prior to the coating process. The straightening process is a process for straightening the glass tube and improving the straightness. For example, the glass tube is inserted into a cylindrical body held so that the axis is substantially horizontal and placed on the inner surface thereof. Then, while heating, the cylindrical body is rotated around its axis to rotate within the cylindrical body, thereby improving the straightness.
JP 2000-340111 A

When the glass tube is rotated in the cylindrical body, the cylindrical body and the glass tube collide with each other, and the outer peripheral surface of the glass tube is damaged. Such scratches on the outer peripheral surface are the largest cause of glass tube breakage during manufacturing and transportation.
By the way, in patent document 1, while heating the glass tube before fluorescent substance suspension application | coating, sulfurous acid gas and oxygen were blown in in the tube, the inner surface of the said glass tube was sulfurized, and the adhesive strength of glass and fluorescent substance Is disclosed. When the sulfurous acid treatment is performed, a part of sodium existing on the inner surface is replaced with sulfur, so that the mechanical strength of the glass tube is improved and the glass tube is hardly damaged. However, since it is not difficult to cause scratches on the outer peripheral surface, which is the largest cause of breakage, it cannot be said that there is a great effect in preventing breakage of the glass tube.

  In view of the above problems, the present invention has as its main object to provide a method for manufacturing a fluorescent lamp and a method for manufacturing a glass tube for a fluorescent lamp, in which the outer peripheral surface of the glass tube is hardly damaged. Another object of the present invention is to provide a fluorescent lamp in which the glass tube is not easily damaged during manufacture or transportation.

In order to solve the above-described problems, the fluorescent lamp manufacturing method according to the present invention corrects the glass tube so as to improve the straightness of the glass tube having a sodium oxide content of 5 wt% or more and 20 wt% or less. A correction process in which the glass tube is placed on a correction tool for heating, and the glass tube is heated and rolled around its axis, and a phosphor layer is formed on the inner surface of the corrected glass tube And forming the sodium sulfate on the outer peripheral surface of the glass tube by heating the glass tube in the presence of sulfurous acid gas and oxygen during the straightening step.
Further, in the method for manufacturing a fluorescent lamp according to the present invention, the glass tube having a sodium oxide content of 5 wt% or more and 20 wt% or less is rotated in the presence of sulfurous acid gas and oxygen while rotating around its axis. A sulfite treatment step for generating sodium sulfate on the outer peripheral surface of the glass tube by heating the glass tube, and a correction tool for correcting the glass tube so as to improve the straightness of the glass tube after the sulfite treatment The glass tube is placed, and the glass tube is rolled and heated for correction, and a correction step for forming a phosphor layer on the inner surface of the corrected glass tube is included.

The method for manufacturing a glass tube for a fluorescent lamp according to the present invention is for correcting the glass tube so as to improve the straightness of the glass tube having a sodium oxide content of 5 wt% or more and 20 wt% or less. The glass tube is placed on a correction tool, and the glass tube is heated and rolled around the axis of the glass tube to correct the glass tube. During the correction step, the glass tube is present in the presence of sulfurous acid gas and oxygen. It is characterized in that a treatment for generating sodium sulfate on the outer peripheral surface of the tube is performed by heating the tube.
In addition, the method for manufacturing a glass tube for a fluorescent lamp according to the present invention includes the presence of sulfurous acid gas and oxygen while rotating a glass tube having a sodium oxide content of 5 wt% or more and 20 wt% or less around its axis. A sulfurous acid treatment process for generating sodium sulfate on the outer peripheral surface of the glass tube by heating the glass tube under the surface, and for correcting the glass tube so as to improve the straightness of the glass tube after the sulfurous acid treatment A correction step of placing the glass tube on a correction tool and rolling and correcting the glass tube while heating.

  The fluorescent lamp manufacturing method and the fluorescent lamp glass tube manufacturing method according to the present invention perform a process of generating sodium sulfate on the outer peripheral surface of the glass tube during the correction process or before the correction process. The outer peripheral surface of the film is coated with sodium sulfate particles, film or layer. Therefore, the slip of the outer peripheral surface is improved, and it is difficult for the outer peripheral surface to be damaged when the glass tube collides with the correction surface or the glass tubes collide with each other in the correction process. Therefore, the glass tube is hardly damaged due to scratches.

In addition, since the glass tube is heated in the presence of sulfurous acid gas and oxygen, a part of sodium existing on the outer peripheral surface is replaced with sulfur, and the mechanical strength of the outer peripheral surface is improved. This also makes it difficult for scratches to occur and the glass tube is difficult to break.
Further, the correction tool is a cylindrical body that is held so that its axis is substantially horizontal, and the glass tube is placed on the inner surface of the correction tool, and the correction tool is rotated around its axis. When rolling the glass tube on the inner surface, it is difficult for the glass tube to fall from the correction tool during the correction process, so that the production yield of the glass tube and the fluorescent lamp is good.

In addition, when the treatment is performed by filling the correction tool on which the glass tube is placed with sulfurous acid gas and oxygen and heating the glass tube during the correction process, it is only for the sulfurous acid treatment. It is not necessary to heat the glass tube at the same time, and since the sulfite treatment can be performed in addition to correcting the glass tube in the correction process, the number of lamp manufacturing processes can be reduced.
Moreover, when the said process is performed by heating the outer peripheral surface of the said glass tube in the atmosphere containing a sulfurous acid gas and oxygen before the said correction process, since it heats only for a sulfurous acid process, it is optimal for a sulfurous acid process. The glass tube can be heated at an appropriate temperature, and the sulfurous acid treatment can be performed efficiently.

  Further, when the treatment is performed by blowing sulfurous acid gas from the crater of the burner to the outer peripheral surface while heating the outer peripheral surface of the glass tube with a burner in an oxygen-containing atmosphere before the correction step, Only the glass tube can be efficiently heated by the burner, and the amount of sulfurous acid gas used can be suppressed because it is only necessary to blow the sulfurous acid gas only to the necessary portion.

In the fluorescent lamp according to the present invention, 2 ng / mm ² or more of sodium sulfate adheres to the outer peripheral surface of the glass tube. Therefore, the outer peripheral surface is slippery, and the outer peripheral surface of the glass tube is hardly damaged in the correction process. Therefore, the glass tube is hardly damaged by scratches and the production yield is good. Further, since the glass tube has few scratches, the glass tube is difficult to break during transportation of the fluorescent lamp.

Hereinafter, a fluorescent lamp manufacturing method, a fluorescent lamp glass tube manufacturing method, and a fluorescent lamp according to an embodiment of the present invention will be described with reference to the drawings.
[Fluorescent lamp]
FIG. 1 is a schematic configuration diagram showing a fluorescent lamp according to the present embodiment. As shown in FIG. 1, a cold cathode fluorescent lamp 1 as a fluorescent lamp according to the present embodiment includes a straight tubular glass tube 3 and cold cathode electrodes 5 sealed at both ends of the glass tube 3. , 7. Further, inside the glass tube 3 sealed at both ends by the electrodes 5 and 7, for example, about 2 mg of mercury as a light emitting substance and a rare gas having a mixing ratio of, for example, 10% argon and 90% neon as a discharge medium are 50 Torr. It is enclosed.

The glass tube 3 has a total length of 800 mm, an inner diameter of 3.0 mm, and a thickness of 0.5 mm. In addition, the full length, the internal diameter, and thickness of the glass tube 3 are not limited to the above. In the case of a general cold cathode fluorescent lamp 1, the total length of the glass tube 3 is 300 to 1500 mm, the inner diameter is 1.4 to 7.0 mm, and the thickness is 0.2 to 0.6 mm.
When using a long glass tube 3 having a total length of 700 mm or more, or a small-diameter thin glass tube 3 having an inner diameter of 3.0 mm or less and a thickness of 0.5 mm or less, scratches generated on the outer peripheral surface of the glass tube 3 Since the glass tube 3 is easily broken as a cause, the method for manufacturing a fluorescent lamp and the method for manufacturing a glass tube for a fluorescent lamp according to the present invention are particularly effective.

The glass tube 3 is made of, for example, soda glass having a softening point of 680 ° C. Since soda glass contains a large amount of sodium oxide (Na ₂ O), sodium is likely to elute on the outer peripheral surface of the glass tube 3. Therefore, it is easy to produce sodium sulfate (Na ₂ SO ₄ ) on the outer peripheral surface of the glass tube 3 by the sulfurous acid treatment described later.
Further, soda glass is easily damaged as compared with borosilicate glass. Therefore, the fluorescent lamp manufacturing method and the fluorescent lamp glass tube manufacturing method according to the present invention in which the outer peripheral surface of the glass tube is hardly damaged are effective.

  The soda glass of the glass tube 3 preferably has a sodium oxide content of 5 wt% to 20 wt%. If it is 5 wt% or more, the probability of the dark start-up time being within one second increases, so the dark startability of the cold cathode fluorescent lamp 1 is improved. If it exceeds 20 wt%, the glass tube 3 will be blackened (brown) or whitened due to long-term use, leading to a decrease in the brightness of the cold cathode fluorescent lamp 1 or a decrease in the mechanical strength of the glass tube 3. .

The soda glass of the glass tube 3 preferably contains titanium oxide (TiO ₂ ) capable of shielding 313 nm ultraviolet rays radiated from mercury. The content of titanium oxide is preferably in the range of 3 to 10 wt%. If it is less than 3 wt%, it is difficult to obtain the effect of shielding ultraviolet rays, and if it exceeds 10 wt%, soda glass does not vitrify and crystallizes immediately after melting.

The soda glass of the glass tube 3 is preferably lead-free in consideration of natural environment protection. However, since lead may be included as an impurity in the manufacturing process, even when lead is included at an impurity level of 0.1 Wt% or less, it is defined as being in the above lead-free category.
The electrodes 5 and 7 include bottomed cylindrical electrode portions 5a and 7a and electrode shafts 5b and 7b attached to the outer surfaces of the bottoms of the electrode portions 5a and 7a. It is attached to the end of the glass tube 3 via In addition, the electron irradiation substance which is not illustrated is apply | coated to the inner surface of electrode part 5a, 7a.

A phosphor layer 11 is formed on the inner surface of the glass tube 3. The phosphor layer 11 is for converting ultraviolet rays (mainly 254 nm) emitted from mercury into predetermined visible light. For example, a blue phosphor is europium activated barium magnesium aluminate [BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ] (abbreviation: BAM-B), green phosphor with cerium / terbium co-activated lanthanum phosphate [LaPO ₄ : Ce ³⁺ , Tb ³⁺ ] (abbreviation: LAP) and red phosphor with europium It is formed of a rare earth phosphor made of active yttrium oxide [Y ₂ O ₃ : Eu ³⁺ ] (abbreviation: YOX).

Examples of usage of the cold cathode fluorescent lamp 1 include a light source of a backlight unit of a liquid crystal display device, a reading light source of a copier, a printer, a scanner, and the like.
[Method of manufacturing fluorescent lamp]
FIG. 2 is a process diagram showing a part of the manufacturing process of the fluorescent lamp. As shown in FIG. 2, the manufacturing process of the cold cathode fluorescent lamp 1 includes a preparation step (step S1) for preparing a straight glass tube, etc., and a correction for correcting the prepared glass tube for improving straightness. Step (Step S2), an application step (Step S3) for applying the phosphor suspension to the inner surface of the corrected glass tube, a drying step (Step S4) for drying the applied phosphor suspension, and a dried phosphor suspension A firing process (step S5) for firing the turbid liquid, a sealing process (step S6) for sealing the electrode to the end of the glass tube after firing, and a process such as an exhaust process, a baking process, and an aging process are included. And in a preparatory process or a correction process, a sulfurous acid process mentioned below is performed. In addition, the said application | coating process, a drying process, and a baking process are a part of formation process which forms a fluorescent substance layer in the inner surface of a glass tube.

(1) Correction Process FIG. 3 is a diagram for explaining a correction tool used in the correction process. As shown in FIG. 3, in the correction process, the glass tube 20 prepared in the preparation process is corrected with the correction tool 22, and the straightness is improved.
The correction tool 22 is a cylindrical body having a total length of 1800 mm, an inner diameter of 15 mm, a thickness of 1.5 mm, and a glass tube 20 that can be accommodated therein. In addition, although the full length, the internal diameter, and thickness of the correction tool 22 are not limited above, at least 1 glass tube 20 must be accommodated in an inside. In particular, the total length of the corrector 22 is preferably longer than the tube length of the glass tube 20 so that the end of the glass tube 20 does not protrude from the corrector 22, so that the entire glass tube 20 can be accommodated with a margin. It is preferable that the length of the glass tube 20 is 50 mm or longer. If the total length of the correction tool 22 is too short, the vicinity of the end of the glass tube 20 cannot be uniformly treated with sulfurous acid, and the straightness near the end of the glass tube 20 is lowered.

The correction tool 22 is made of a material having a higher softening point than the soda glass of the glass tube 20, for example, quartz glass (softening point: 1000 ° C.), and the inner surface thereof is a smooth correction surface 24.
The correction tool 22 is held by a plurality of rollers 26a to 26d so that its axis is substantially horizontal. The rollers 26a to 26d are respectively attached to drive shafts 28a and 28b connected to a rotation drive mechanism (not shown). When the drive shafts 28a and 28b are rotated in the direction of arrow A by the rotation drive mechanism, the rollers 26a to 26d are driven. Each roller 24a-24d rotates in the direction of arrow B in conjunction with the shafts 28a, 28b. Further, as each of the rollers 24a to 24d rotates, the correction tool 22 rotates in the direction of the arrow C around its axis.

  When correcting the glass tube 20, first, for example, four glass tubes 20 are inserted into the correction tool 22, and the glass tubes 20 are placed on the correction surface 24. Since the axis of the cylindrical body 22 is substantially horizontal, the correction surface 24 is also approximately horizontal, and the axis of the glass tube 20 placed on the correction surface 24 is also approximately horizontal. When the correction tool 22 is rotated in the direction of arrow C while the glass tube 20 is housed inside, each glass tube 20 rotates in the direction of arrow D around the axis on the correction surface 28, and straightness is improved. To be corrected.

Note that the number of glass tubes 20 inserted into the cylinder 22 is not limited to four, and may be adjusted to an efficient number according to the inner diameter of the correction tool 22 and the outer diameter of the glass tube 20.
FIG. 4 is a diagram for explaining a case where sulfite treatment is performed during the correction process. As shown in FIG. 4, the correction tool 22 is disposed in the heating furnace 30. When the glass tube 20 is rotated on the correction surface 24 for correction, the glass tube 20 must be heated at, for example, 560 ° C. by adjusting the temperature in the heating furnace 30. In addition, heating temperature is not restricted to 560 degreeC, It adjusts according to the physical property of soda glass.

(2) Application Step and Drying Step FIG. 5 is a diagram for explaining the application step and the drying step. First, as shown in FIG. 5 (a), the lower end opening 40 of the glass tube 20 is immersed in the phosphor suspension 42, and the air in the tube is sucked from the upper end opening 44 of the glass tube 20 to apply the coating process. And the phosphor suspension 42 is sucked up to a predetermined position in the tube.

As the phosphor suspension 42, for example, a mixture of phosphor, binder, binder and organic solvent is used. For example, nitrocellulose is used for the binder, low-melting glass powder represented by barium calcium borate or the like is used for the binder, and butyl acetate is used for the organic solvent.
Next, the suction of air is stopped, the lower end opening 40 is pulled up from the phosphor suspension 42, the upper end opening 44 is opened, and the phosphor suspension 42 is removed from the lower end opening 40 as shown in FIG. To discharge from. Thereby, the phosphor suspension 42 is applied to the inner surface of the glass tube 20.

  By the way, the small diameter glass tube 20 is difficult to obtain straightness at the time of manufacture, and tends to bend easily. FIG. 6 is a diagram schematically showing that thickness unevenness occurs in the phosphor suspension when the glass tube is bent. As shown in FIG. 6, for example, if the glass tube 20 is bent at the portion indicated by the symbol X, the thickness of the phosphor suspension 42 is uneven below the bent portion. In this case, the thickness unevenness occurs, and the light characteristics such as the luminance and the color temperature of the cold cathode fluorescent lamp 1 become unstable and the commercial value is lowered. Therefore, when the glass tube 20 has a small diameter, it is necessary to improve the straightness of the glass tube 40 by performing a correction process before the coating process.

Next, in the drying step, as shown in FIG. 5C, drying air 46 is caused to flow from the upper end opening 44, hot air is applied to the glass tube 20 from the outside, and the applied phosphor suspension 42 is dried. To promote.
(3) Firing step In the firing step, the dried phosphor suspension 42 is fired to form the phosphor layer 11. In the baking process, the correction tool 22 used in the correction process shown in FIG. 3 is used.

First, the glass tube 20 in which the phosphor suspension 42 is dried is inserted into the correction tool 22, and the temperature of the heating furnace 30 is increased while the glass tube 20 is rotated in the correction tool 22, so that the glass tube 20 Heat to 620 ° C. Thus, heat can be uniformly applied to the phosphor suspension 42 by heating the glass tube 20 while rotating it.
Thus, also when rotating the glass tube 20 using the correction tool 22 in a baking process, if the sodium sulfate adheres to the outer peripheral surface of the said glass tube 20, the said outer peripheral surface will be hard to be damaged. In addition, the operation | work which rotates the glass tube 20 using the correction tool 22 is not essential in a baking process, and should just be performed as needed.

The glass tube 20 obtained as described above is processed into the glass tube 3 of the cold cathode fluorescent lamp 1.
(4) Sealing step In the sealing step, the electrodes 5 and 7 are sealed to the end portion of the glass tube 3, and the end portion of the glass tube 3 is sealed by this sealing.

  In the sealing step, first, the electrode shafts 5b and 7b are inserted into the axial through holes in the middle of the spherical beads 9, and the beads 9 and the electrode shafts 5b and 7b are fixed in an airtight manner. Then, the electrodes 5 and 7 fixed to the beads 9 are inserted into predetermined positions of the glass tube 3, and the end of the glass tube 3 is heated using, for example, a burner, and the outer periphery of the beads 9 and the inside of the glass tube 3 are Fuse the circumference.

The temperature of the edge part of the glass tube 3 in this process is 800-1200 degreeC. In addition, the adhesion process of the electrodes 5 and 7 can be implemented with the same well-known technique as before.
<Sulfurous acid treatment>
Next, a description will be given sulphite process of adhering to the outer peripheral surface of the glass tube to form sodium sulfate (Na 2 _{SO 4).} In the sulfurous acid treatment, sodium sulfate is generated on the outer peripheral surface of the glass tube 20 by heating it in the presence of sulfurous acid gas and oxygen. If sulfurous acid gas and oxygen are blown into the correction tool 22 during the correction process, the glass tube 20 is placed in the presence of sulfurous acid gas and oxygen.

Note that oxygen may be blown in by blowing air containing oxygen. Further, a gas other than air containing oxygen may be blown in, or sulfur dioxide gas may be included in the gas.
Specifically, in the sulfurous acid treatment, as shown in FIG. 4, an air supply pipe 32 is arranged on one opening side of the correction tool 22, and an exhaust pipe 34 is arranged on the other opening side. Sulfurous acid gas and air are supplied into the correction tool 22, and the sulfurous acid gas and air in the correction tool 22 are exhausted from the exhaust pipe 34. By using the air supply pipe 32 and the exhaust pipe 34 in this manner, the sulfurous acid gas and air flow without stagnation in the correction tool 22, and the sulfurous acid gas and air can be supplied to the entire outer peripheral surface of the glass tube 20 without unevenness. . Further, the sulfurous acid gas is difficult to leak out of the correction tool 22.

The supply pipe 32 and the exhaust pipe 32 are not necessarily used. For example, the sulfurous acid gas and air are not blown directly into the correction tool 22 from the air supply pipe 32, but the sulfurous acid gas and air flow into the correction tool 22 by filling the heating furnace 30 with the sulfurous acid gas and air. Also good. Moreover, you may exhaust naturally without using an exhaust pipe.
Furthermore, the correction tool 22 may be sealed so that sulfurous acid gas does not leak out of the correction tool 22. Alternatively, a heat decomposable compound that generates sulfurous acid gas may be introduced into the correction tool 22 and the heat decomposable compound may be thermally decomposed in the correction tool 22 to supply the sulfurous acid gas.

  In the case of performing sulfite treatment, it is necessary to heat the glass tube 20, but since the heating temperature may be the same as the temperature at which the glass tube 20 is straightened, it is not particularly necessary to heat for the sulfurous acid treatment. If sulfurous acid gas and air are supplied into the correction tool 22 inside, sulfurous acid treatment can be performed simultaneously with correction. Sodium sulfate is formed when the heating temperature is 200 to 400 ° C. In addition, since the glass tube 20 is rotating during the correction, the entire outer peripheral surface of the glass tube 20 can be uniformly treated with sulfite.

The sulfurous acid treatment is not limited to being performed during the correction process, and may be performed before the correction process. If sodium sulfate is attached to the outer peripheral surface of the glass tube 20 in advance before the correcting step, the outer peripheral surface of the glass tube 20 can be prevented from being damaged in the subsequent correcting step.
7 and 8 are diagrams for explaining the case where the sulfurous acid treatment is performed before the correction process.

  As an example of performing the sulfurous acid treatment before the correction process, it is conceivable to heat the outer peripheral surface of the glass tube in an atmosphere containing sulfurous acid gas and air. For example, as shown in FIG. 7, the outer peripheral surface of the glass tube 20 may be heated by burners 52a and 52b in a state where sulfurous acid gas and oxygen are contained in the atmosphere of the processing space 50 in which the glass tube 20 is disposed. Conceivable. In order to uniformly heat the outer peripheral surface of the glass tube 20, the burners 52 a and 52 b are moved along the axis of the glass tube 20 while rotating the glass tube 20 around its axis with a jig (not shown). It is conceivable to heat.

  Further, as another example of the case where the sulfurous acid treatment is performed before the correction process, the outer peripheral surface of the glass tube 20 is heated with a burner in an oxygen-containing atmosphere, and sulfurous acid gas is discharged from the crater of the burners 52a and 52b. It is possible to spray on the surface. For example, as shown in FIG. 8, the outer peripheral surface of the glass tube 20 is heated by the burners 56 a and 56 b in a state where oxygen is contained in the atmosphere of the processing space 54 in which the glass tube 20 is arranged. It is considered that sulfurous acid gas is sprayed from the craters 56a and 56b and sprayed on the outer peripheral surface of the glass tube 20. At this time, it is also possible to heat the burners 56a and 56b along the axis of the glass tube 20 while rotating the glass tube 20 around its axis with a jig (not shown) in the same manner as described above. It is done.

In addition, as other methods of sulfurous acid treatment, a method of spraying sulfurous acid gas on the outer peripheral surface of a glass tube that has not been cooled immediately after the tube drawing step in the preparation step, or a thermally decomposable compound that generates sulfurous acid gas in a heated glass tube The method of spraying can be considered.
<Effect of sulfurous acid treatment>
It was confirmed by experiments that sodium sulfate adheres to the outer peripheral surface of the glass tube, so that the outer peripheral surface is less likely to be damaged in the correction process. Specifically, the glass tube treated with sulfurous acid was subjected to a correction process, and it was evaluated whether or not the outer peripheral surface of the glass tube was damaged. The glass tube used was made of lead-free soda glass having a total length of 200 mm, an inner diameter of 3.0 mm, and a thickness of 0.5 mm.

When at least one of the following (a) to (f) corresponds, it was evaluated that there was a scratch on the outer peripheral surface, and when it did not correspond to any of the following, it was evaluated that there was no scratch.
(A) When a scratch having a maximum width of 0.3 mm or more has occurred.
(B) A case where a scratch having a maximum width exceeding 0.2 mm occurs and the length of the scratch (the total length when there are a plurality of scratches) is 20 mm or more.
(C) A case where a scratch having a maximum width exceeding 0.2 mm occurs and the scratch extends over a half or more in the circumferential direction of the glass tube.
(D) A case where the circumferential damage of the glass tube occurs at a density of 1 or more per 1 mm in the tube axis direction over 5 mm or more in the tube axis direction.
(E) When scratches (scratches with a volume of a portion swollen by scratches of 1 mm ³ or more) that may progress to cracks such as dents have occurred.
(F) A scratch having a maximum depth of 0.3 mm or more has occurred.

The incidence of scratches on the outer peripheral surface is the number of glass tubes with scratches relative to the number of all glass tubes subjected to the correction process.
FIG. 9 is a graph showing the relationship between the amount of sodium sulfate attached and the incidence of scratches. Usually, in a glass tube not subjected to bisulfite treatment, sodium sulfate on the outer circumferential surface thereof is adhered 1.5 ng / mm ² approximately, as shown in FIG. 9, 1.5 ng / mm ² of about adhesion amount Then, the incidence of scratches is 100%. However, when 4 ng / mm ² or more of sodium sulfate per unit area adhered to the outer peripheral surface of the glass tube, the incidence of scratches on the outer peripheral surface decreased to 40%. Further, when 8 ng / mm ² or more of sodium sulfate was adhered per unit area, the outer peripheral surface was not damaged.

As can be seen from FIG. 9, when sodium sulfate adheres, the incidence of scratches on the outer peripheral surface decreases. That is, if the sulfurous acid treatment is performed, the occurrence rate of scratches on the outer peripheral surface decreases.
Even if the error is estimated, it is considered that 2.0 ng / mm ² or more of sodium sulfate does not adhere to the outer peripheral surface of the glass tube not subjected to the sulfurous acid treatment. Therefore, it is presumed that the glass tube having ² ng / mm ² or more of sodium sulfate attached to the outer peripheral surface is a glass tube subjected to the sulfite treatment according to the present invention. And the glass tube in which ² ng / mm ² or more of sodium sulfate adheres to the outer peripheral surface has a low incidence of scratches on the outer peripheral surface.

[Others]
<About the heating conditions of the straightening process>
When the soda glass contains titanium oxide, the heating in the correction process may be performed under a temperature condition lower than the temperature at which the titanium oxide crystal nuclei are generated. The optimum temperature condition for the straightening process was determined from the relationship between the straightening degree of the glass tube and the heating temperature.

  FIG. 10 is a diagram for explaining the measurement of the degree of correction of the glass tube. As shown in FIG. 10, the measurement of the degree of correction of the glass tube 20 is performed when the glass tube 20 is supported at both ends in a state where the glass tube 20 is rotatable about its axis and the glass tube 20 is rotated. Then, displacement at the outer periphery of the central portion of the glass tube 20 (hereinafter, this difference is also referred to as “bend”), that is, “Y” in the figure is measured, and the determination is made based on the magnitude of this Y value.

  The correction degree of the glass tube 20 when the temperature is changed with the time for heating the glass tube 20 constant in the correction step is such that the temperature GT of the glass tube 20 is in the range of 480 to 610 ° C., preferably 520 to It has been found that when the temperature is within the range of 580 ° C., the glass tube 20 is less bent. In the present embodiment, the temperature GT of the glass tube 20 in the correction process is set to 560 ° C.

The range of the temperature GT of the glass tube is a glass transition point T of the glass tube 20 (in the embodiment, 510 ° C. The glass point transfer T is a glass tube production lot and is 490 to 510 ° C. Therefore, if the temperature GT (° C.) of the glass tube is expressed using the above-mentioned 510 ° C. is a target value at the time of manufacture, the following equation is obtained.
T-30 ≦ GT ≦ T + 100
In addition, the viscosity of the glass material in this range (480 to 610 ° C.) is 10 ¹¹ to 10 ¹⁴ dPa · sec.

In the case of the cold cathode fluorescent lamp 1, for example, it is used as a light source of a backlight unit of a liquid crystal display device. In recent years, the display screen of the liquid crystal display device has been enlarged, and along with this, a lamp having a long overall length (for example, 700 mm or more) is used.
However, when a long lamp is manufactured by a conventional method, the luminance unevenness of the lamp tends to increase. This is due to the large bending of the glass tube constituting the lamp (treatment in the correction process is performed by a conventional method), and the phosphor layer formed on the inner surface of the glass tube due to this bending. This is thought to be due to variations in thickness. When the bending of the glass tube is 0.2 mm or more, the thickness unevenness of the phosphor layer formed on the inner surface of the glass tube increases.

However, even if the total length of the glass tube is 700 mm or more, if the temperature of the glass tube in the straightening process is 560 ° C., the bending can be made less than 0.2 mm. In other words, when the treatment in the correction process is performed so that the temperature of the glass tube is 560 ° C., it is possible to suppress the formation of a cloudy portion at the end of the lamp and to efficiently correct the bending of the glass tube.
<About the cloudy part>
As described above, the soda glass of the glass tube preferably contains titanium oxide (TiO ₂ ) capable of shielding the 313 nm ultraviolet rays emitted from mercury. However, when titanium oxide is contained in soda glass, the vicinity of the end of the glass tube becomes cloudy blue (this portion is referred to as “blue cloudy portion”).

  The cloudy part is a crystallized titanium oxide. First, the glass temperature is around 600 ° C., and crystal nuclei of titanium oxide that eventually becomes a cloudy part are formed (around 600 ° C.). The crystal nucleus grows when the temperature of the glass is around 990 ° C. (there is a peak where the crystal nucleus grows around 990 ° C.), and this is the cloudiness part. It is thought that it becomes.

In the manufacture of the fluorescent lamp, the temperature of the glass tube in both the correction process and the firing process is, for example, 520 to 580 ° C., and the temperature of the end of the glass tube and the surrounding area in the subsequent sealing process is, for example, 800-1200 degreeC.
From the above, it is considered that the generation mechanism of the bluish portion when the fluorescent lamp is manufactured by the conventional method is as follows.

First, in the correction process and the drying process, the glass tube is heated to 520 to 580 ° C., and crystal nuclei of titanium oxide are generated in the entire glass tube (this state cannot be visually observed). In the subsequent sealing step, the end of the glass tube and the periphery thereof are heated to 800 to 1200 ° C., and crystal nuclei existing in the periphery of the end of the heated glass tube grow and become cloudy. Become a part.
Here, the cloudy part is generated on the center side of the end of the glass tube because the temperature of the end of the glass tube in the sealing step is higher than 990 ° C., for example, near 1200 ° C. Thus, it is considered that at the position moved to the central portion side from the end portion, the temperature is lower than that of the end portion and is around 990 ° C. which is a peak at which crystal nuclei grow.

In order to suppress the occurrence of the cloudy part, the temperature at the time of processing of the glass tube in the correction process and the firing process is made lower than the temperature at which the crystal nucleus of titanium oxide is generated, and the end of the glass tube in the sealing process (the surrounding area) It is preferable to perform the treatment at a temperature lower than that at which crystal nuclei grow.
On the other hand, the heating conditions of the firing process are determined according to the suspension used to form the phosphor layer, and as long as the same suspension is used, it is not easy to change the heating conditions of the firing process. Absent. In the sealing step, when the electrode is sealed to the end of the glass tube, it is necessary to melt the end of the glass tube, and it is difficult to lower the temperature under the current heating conditions. On the other hand, it is relatively easy to make the temperature at the time of processing the glass tube in the correction process lower than the temperature at which the crystal nucleus of titanium oxide is generated.

In order to conduct a confirmation test of the suppression of the cloudy part, the temperature at the time of processing the glass tube in the straightening process was made lower than the temperature at which the crystal nuclei of titanium oxide were generated, and as a result, the fluorescent lamp was manufactured. There was no such occurrence of a cloudy part.
In the confirmation test, 100 fluorescent lamps were manufactured and the occurrence rate of the cloudy part was investigated. As a result of the investigation, the occurrence rate in the above-described method was 0%, and the occurrence rate in the conventional method was 100%. From this result, it can be seen that, in the correction process, it is effective to reduce the heating temperature of the glass tube to suppress the generation of the cloudy part.

[Modification]
As mentioned above, although this invention has been demonstrated based on embodiment, it cannot be overemphasized that this invention is not restricted to an above-described form, For example, it can also be set as the following forms.
<Variation of fluorescent lamp>
(1) Kind of lamp The fluorescent lamp according to the present invention described in the above embodiment is a cold cathode fluorescent lamp having a cold cathode type electrode in a glass tube. Instead, a hot cathode fluorescent lamp using a hot cathode electrode may be used. Note that examples of using a hot cathode fluorescent lamp include a fluorescent lamp for general illumination, such as a compact fluorescent lamp and a bulb-type fluorescent lamp.

The present invention can also be applied to other fluorescent lamps. As another fluorescent lamp, there is an external electrode fluorescent lamp, and the external electrode fluorescent lamp will be described below.
FIG. 11 is a plan sectional view showing a schematic configuration of the external electrode type fluorescent lamp. As shown in FIG. 11, the external electrode type fluorescent lamp 61 includes a glass tube 63 sealed at both ends, and electrodes 65 and 67 provided at both ends of the glass tube 63, and performs dielectric barrier discharge. For example, it is used as a light source of a backlight unit.

Inside the glass tube 63 sealed at both ends, similarly to the cold cathode fluorescent lamp 1, a discharge medium such as mercury or a rare gas (eg, argon, neon) as a buffer gas is provided at a predetermined sealing pressure. It is enclosed. Further, a phosphor layer 69 is formed on the inner surface of the glass tube 63 as in the embodiment.
For example, lead-free soda glass is used for the glass tube 63, and titanium oxide capable of shielding ultraviolet rays of 313 nm is added in a range of 3 to 10 wt%, for example, 4 wt%, as in the embodiment. ing. If the content of titanium oxide exceeds 10 wt%, it will crystallize immediately after melting without vitrification.

  The electrodes 65 and 67 are made of, for example, an aluminum metal foil, and are attached so as to cover the outer periphery of the glass tube with a conductive adhesive in which metal powder is mixed with silicon resin. As the conductive adhesive, fluorine resin, polyimide resin, epoxy resin, or the like may be used instead of silicon resin, and, for example, magnesium oxide (MgO) that is a transparent electrode may be used as the electrode. In the case of using transparent electrodes, the conventional manufacturing method may show a cloudy part near the end of the glass tube, but the crystal nucleus of titanium oxide generates the temperature during processing of the glass tube in the correction process. When the temperature is lower than the applied temperature, generation of a cloudy portion can be suppressed.

Further, instead of sticking the metal foil to the glass tube with the conductive adhesive, the electrode may be formed by applying a silver paste to the entire circumference of the electrode forming portion of the glass tube. Furthermore, the electrodes 65 and 67 have a cylindrical shape, but may have a cap shape that covers the end of the glass tube, for example.
The external electrode fluorescent lamp 61 is manufactured by performing the following steps in that order. That is, a preparation step for preparing a straight glass tube, a correction step for correcting the bending of the prepared glass tube, an application step for applying a suspension containing a phosphor on the inner surface of the corrected glass tube, Drying process for drying the suspension, firing process for firing the dried suspension, sealing process for sealing the ends of the glass tube after firing, mounting for attaching electrodes to both ends of the sealed glass tube It is manufactured through processes.

Similarly to the embodiment, the straightening process is also carried out by being placed on the straightening surface of the cylindrical body with the temperature in the heating furnace set so that the temperature of the glass tube is 560 ° C.
When applied to an external electrode fluorescent lamp, the dark startability particularly required as the light source of the backlight unit is improved because the glass tube is made of soda glass. That is, since soda glass contains a large amount of sodium oxide (Na ₂ O), the sodium (Na) component elutes on the inner surface of the glass tube over time. Since sodium has a low electronegativity, sodium eluted on the inner surface of the end of the glass tube (without a protective film) contributes to the improvement of the dark startability.

The present invention is also applicable to a hot cathode fluorescent lamp having a hot cathode as an internal electrode.
(2) Lamp Shape The fluorescent lamp in the embodiment has a straight tube shape, but the shape of the fluorescent lamp according to the present invention is not particularly limited, and for example, a “U” shape or a “V” shape. , “W” shape may be used, and furthermore, a shape in which a plurality (eg, three) of “U” shape glass tubes are connected may be used. Further, the fluorescent lamp is not limited to a circular cross section, and may be a flat fluorescent lamp having an elliptical shape or a circular long hole.

For example, when the shape of the fluorescent lamp is changed to “U” shape, a deformation process for deforming the straight glass tube into “U” shape is performed after the phosphor layer is formed or the electrode is at the end. It can be carried out if it is performed after the provision. The flat fluorescent lamp can be implemented by once producing a fluorescent lamp having a circular cross section and then flattening the glass tube.
(3) Metal oxide that blocks ultraviolet rays In the embodiment, titanium oxide is used as the metal oxide that blocks ultraviolet rays. However, other metal oxides may be used. Note that it is necessary to shield ultraviolet rays of 313 nm, and examples of such metal oxides include cerium oxide (CeO ₂ ), molybdenum oxide (MoO ₃ ), and tungsten oxide (WO ₃ ). However, regarding the suppression of the occurrence of the cloudy part, the temperature for promoting the formation and growth of crystal nuclei in these metal oxides is different from that of titanium oxide. It is necessary to determine heating conditions such as a stopping process.

(4) Protective film A protective film may be formed on the inner surface of the glass tube. In this case, a phosphor layer is formed on the protective film. The protective film is made of, for example, silica (SiO ₂ ). The protective film blocks the elution of sodium (Na), which is one of the components of the glass tube, into the discharge space, and prevents mercury consumption due to the reaction between the sodium and mercury. The protective film may be formed of alumina (Al ₂ O ₃ ).

(5) Fluorescent substance layer The structure of a fluorescent substance layer is not limited to said structure, For example, the following modifications can be considered.
(5-1) Ultraviolet Absorption For example, in recent years, with the increase in size of liquid crystal color televisions, polycarbonate having good dimensional stability is used for the diffusion plate that closes the opening of the backlight unit. This polycarbonate is easily deteriorated by ultraviolet rays having a wavelength of 313 (nm) emitted from mercury. In such a case, a phosphor that absorbs ultraviolet rays having a wavelength of 313 (nm) may be used. Examples of phosphors that absorb ultraviolet rays of 313 (nm) include the following.

(A) Blue europium / manganese co-activated barium aluminate / strontium / magnesium [Ba _1-xy Sr _x Eu _y Mg _1-z Mn _z Al ₁₀ O ₁₇ ] or [Ba _1-xy Sr _x Eu _{y Mg 2-z Mn z Al} 16 O 27]
Here, x, y, and z are preferably numbers satisfying the conditions of 0 ≦ x ≦ 0.4, 0.07 ≦ y ≦ 0.25, and 0 ≦ z <0.1, respectively.

Examples of such phosphors include europium activated barium magnesium aluminate [BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ], [BaMgAl ₁₀ O ₁₇ : Eu ²⁺ ] (abbreviation: BAM-B), and europium attached. There are active barium aluminate / strontium / magnesium [(Ba, Sr) Mg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ ], [(Ba, Sr) MgAl ₁₀ O ₁₇ : Eu ²⁺ ] (abbreviation: SBAM-B), and the like.

(B) Green • Manganese inactive magnesium gallate [MgGa ₂ O ₄ : Mn ²⁺ ] (abbreviation: MGM)
Manganese activated cerium aluminate, magnesium, zinc [Ce (Mg, Zn) Al ₁₁ O ₁₉ : Mn ²⁺ ] (abbreviation: CMZ)
Terbium-activated cerium aluminate / magnesium [CeMgAl ₁₁ O ₁₉ : Tb ³⁺ ] (abbreviation: CAT)
Europium / manganese co-activated barium aluminate / strontium / magnesium [Ba _1-xy Sr _x Eu _y Mg _1-z Mn _z Al ₁₀ O ₁₇ ] or [Ba _1-xy Sr _x Eu _y Mg _{2 -z} Mn _z Al ₁₆ O _27]
Here, x, y and z are numbers satisfying the conditions of 0 ≦ x ≦ 0.4, 0.07 ≦ y ≦ 0.25, and 0.1 ≦ z ≦ 0.6, respectively, and z is 0.4 It is preferable that ≦ x ≦ 0.5.

Examples of such phosphors include europium / manganese co-activated barium aluminate / magnesium [BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ ], [BaMgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ ] (abbreviation). : BAM-G), europium / manganese co-activated barium aluminate / strontium / magnesium [(Ba, Sr) Mg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ , Mn ²⁺ ], [(Ba, Sr) MgAl ₁₀ O ₁₇ : Eu ²⁺ , Mn ²⁺ ] (abbreviation: SBAM-G).

(C) Red • Europium activated phosphorus • Yttrium vanadate [Y (P, V) O ₄ : Eu ³⁺ ] (abbreviation: YPV)
Europium activated yttrium vanadate [YVO ₄ : Eu ³⁺ ] (abbreviation: YVO)
Europium-activated yttrium oxysulfide [Y ₂ O ₂ S: Eu ³⁺ ] (abbreviation: YOS)
Manganese-activated magnesium fluoride germanate [3.5MgO.0.5MgF ₂ .GeO ₂ : Mn ⁴⁺ ] (abbreviation: MFG)
Dysprosium-activated yttrium vanadate [YVO ₄ : Dy ³⁺ ] (red and green two-component phosphor, abbreviation: YDS)
In addition, you may mix and use the fluorescent substance of a different compound with respect to one type of luminescent color. For example, BAM-B (absorbs 313 nm) in blue only, and cerium / terbium co-activated lanthanum phosphate [LaPO ₄ : Ce ³⁺ , Tb ³⁺ ] (abbreviation: LAP) (absorbs 313 nm) in green. Fluorescence of BAM-G (absorbs 313 nm), europium activated yttrium oxide [Y ₂ O ₃ : Eu ³⁺ ] (abbreviation: YOX) (absorbs 313 nm) and YVO (absorbs 313 nm) in red. The body may be used. In such a case, as described above, the phosphor that absorbs the wavelength 313 (nm) is adjusted so that the total weight composition ratio is larger than 50%, so that the ultraviolet ray almost leaks out of the glass tube. Can be prevented. Accordingly, when the phosphor layer contains a phosphor that absorbs ultraviolet rays of 313 [nm], deterioration due to ultraviolet rays such as a diffusion plate made of polycarbonate (PC) that closes the opening of the backlight unit is suppressed. The characteristics as a light unit can be maintained for a long time.

  Here, “absorbing ultraviolet rays of 313 (nm)” means an excitation wavelength spectrum near 254 (nm) (excitation wavelength spectrum means that excitation light is emitted while changing the wavelength of the phosphor, and the excitation wavelength and emission intensity are changed. It is defined that the intensity of the excitation wavelength spectrum of 313 (nm) is 80 (%) or more, where the intensity is plotted (100). That is, the phosphor that absorbs ultraviolet rays of 313 (nm) is a phosphor that can absorb ultraviolet rays of 313 (nm) and convert it into visible light.

(5-2) High color reproduction Liquid crystal display devices typified by liquid crystal color televisions are used as a light source for a backlight unit of the liquid crystal display device in accordance with the recent high color reproduction performed as part of the improvement in image quality. There is a need to expand the reproducible chromaticity range in the cold cathode fluorescent lamp and the external electrode fluorescent lamp.

  In response to such a request, for example, by using the following phosphor, the chromaticity range can be expanded as compared with the case of using the phosphor in the embodiment. Specifically, in the CIE1931 chromaticity diagram, the chromaticity coordinate value of the phosphor for high color reproduction includes a triangle formed by connecting the chromaticity coordinate values of the three phosphors used in the embodiment. Located at the coordinates that expand the reproduction range.

(A) Blue • Europium activated strontium chloroapatite [Sr ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ ] (abbreviation: SCA), chromaticity coordinates: x = 0.153, y = 0.030
In addition to the above, europium-activated strontium, calcium, barium, chloroapatite [(Sr, Ca, Ba) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ ] (abbreviation: SBCA) can also be used, and the wavelength 313 (nm) SBAM-B, which can absorb the ultraviolet rays, can also be used for high color reproduction.

(B) Green BAM-G, chromaticity coordinates: x = 0.136, y = 0.572
CMZ, chromaticity coordinates: x = 0.164, y = 0.722
CAT, chromaticity coordinates: x = 0.284, y = 0.635
Terbium / manganese co-activated cerium aluminate / magnesium [CeMgAl ₁₁ O ₁₉ : Tb ³⁺ , Mn ²⁺ ] (abbreviation: CAM), chromaticity coordinates: x = 0.256, y = 0.657
Manganese-activated zinc silicate [Zn ₂ SiO ₄ : Mn ²⁺ ] (abbreviation: ZSM), chromaticity coordinates: x = 0.248, y = 0.700
As described above, these can also absorb ultraviolet rays having a wavelength of 313 (nm), and besides the three phosphor particles described here, MGM can also be used for high color reproduction.

(C) Red • YOS, chromaticity coordinates: x = 0.658, y = 0.330
YVO, chromaticity coordinates: x = 0.661, y = 0.328
MFG, chromaticity coordinates: x = 0.708, y = 0.288
As described above, these can also absorb ultraviolet rays having a wavelength of 313 (nm), and besides the three phosphor particles described here, YPV and YDS can also be used for high color reproduction.

  In addition, the chromaticity coordinate values shown above are representative values measured only with each phosphor powder, and due to the measurement method (measurement principle), etc., the chromaticity coordinates indicated by each phosphor powder The value may be slightly different from the value listed above. For reference, the chromaticity coordinate values of the phosphor powders of the first embodiment are YOX (x = 0.463, y = 0.348), LAP (x = 0.351, y = 0.585). , BAM-B (x = 0.148, y = 0,055).

Furthermore, the phosphor used for emitting each color of red, green, and blue is not limited to one type for each wavelength, and a plurality of types may be used in combination.
Here, the case where a phosphor layer is formed using the above-described phosphor particles for high color reproduction will be described. In this evaluation, there are three evaluations in the case of using a phosphor for high color reproduction based on the area of the NTSC triangle (NTSC triangle) connecting the chromaticity coordinate values of the three primary colors of the NTSC standard in the CIE1931 chromaticity diagram. This is performed by the ratio of the area of the triangle that can connect the chromaticity coordinate values (hereinafter referred to as NTSC ratio).

  For example, when BAM-B is used as blue, BAM-G as green, and YVO as red (Example 1), the NTSC ratio is 92 (%), and SCA is used as blue, BAM-G as green, and YVO as red. (Example 2) NTSC ratio is 100%, and when SCA is used as blue, BAM-G as green, and YOX as red (Example 3), NTSC ratio is 95 (%). The luminance can be improved by 10 (%) compared to the above.

The chromaticity coordinate values used for the evaluation here are measured in a state where a liquid crystal display device incorporating a lamp or the like is used.
<Modification of manufacturing method>
(1) Correction process The correction process may be a process in which a glass tube made of soda glass is placed on a correction tool for correcting straightness, and the glass tube is rolled and corrected while being heated. For example, it is conceivable to correct as follows.

FIG. 12 is a schematic diagram showing a bridge correction process according to a modification. As shown in FIG. 12, in the correction process according to the modification, a pair of rollers 72 and 74 disposed in the heating furnace 70 is a correction tool.
The rollers 72 and 74 are arranged so that their axes are substantially horizontal and parallel to each other. When the glass tube 20 is placed on the outer peripheral surfaces 76 and 78 of the rollers 72 and 74 so that the axis of the glass tube 20 and the axis of the rollers 72 and 74 are parallel to each other, the outer peripheral surface of the glass tube 20 is both. It will be in the state which contacted the outer peripheral surfaces 76 and 78.

  In this state, if the temperature in the heating furnace 70 is set to about 560 ° C., for example, and the rollers 72 and 74 are rotated in the same direction, for example, in the direction of the arrow E by a driving mechanism (not shown), the glass tube 20 is corrected. Rotate in the direction of arrow F above. Thereby, the correction which improves the straightness of the glass tube 20 can be performed. Note that it is preferable to appropriately adjust the temperature in the heating furnace 70, the rotation speed of the rollers 72 and 74, and the like according to the total length, inner diameter, thickness or material of the glass tube 20.

As a modified example of the correction process, in addition to the above, for example, a glass tube is placed on the surface of the correction tool having a correction surface for rolling the glass tube, and the correction tool is perpendicular to the tube axis of the glass tube. It is conceivable that the glass tube is rolled while being swung on the correction surface so that the straightness is improved.
The correction surface may be flat or curved as long as the glass tube can be rolled. If the correction surface is curved, both sides of the oscillating direction of the correction surface are warped upward so that the glass tube does not fall from the correction surface when rolled, for example, the tube axis of the placed glass tube and It is preferable that the cross section of the correction surface when cut along the orthogonal plane is an arc shape with an open top or a “U” shape.

(2) Heating temperature in the straightening process In the embodiment, the temperature of the glass tube in the straightening process was set to 560 ° C. in order to suppress the generation of crystal nuclei that would become a cloudy part. As described above, it is considered that the same effect can be obtained by lowering the temperature of the glass tube in the firing step or the temperature of the end (including the periphery) of the glass tube in the sealing step. Naturally, the temperature of the glass tube in both steps is made lower than the peak temperature at which crystal nuclei are generated in the straightening process and the firing process, and the temperature at the end of the glass tube and its surroundings is crystal nuclei in the sealing process. Each treatment may be performed so that the temperature is lower than the peak temperature at which the growth is performed.

However, as described above, when changing the heating conditions of the firing step, it is necessary to adjust the components of the suspension or change the solvent to be used.
Moreover, when changing the heating conditions in the sealing step, it is necessary to consider a sealing method. In addition, if a sealing process is sealed, for example using cement etc., it will be unnecessary to heat and it is thought that a cloudy part can be suppressed.

  The method for manufacturing a fluorescent lamp according to the present invention can be used to manufacture a fluorescent lamp with little glass tube breakage.

It is a schematic block diagram which shows the fluorescent lamp which concerns on this Embodiment. It is process drawing which shows a part of manufacturing process of a fluorescent lamp. It is a figure for demonstrating the correction tool used at a correction process. It is a figure explaining the case where a sulfurous acid process is performed during a correction process. It is a figure for demonstrating an application | coating process and a drying process. It is a figure which shows typically that thickness nonuniformity arises in fluorescent substance suspension when a glass tube is bent. It is a figure explaining the case where a sulfurous acid process is performed before a correction process. It is a figure explaining the case where a sulfurous acid process is performed before a correction process. It is a figure which shows the relationship between the adhesion amount of sodium sulfate, and the incidence rate of a damage | wound. It is a figure explaining the measurement of the correction degree of a glass tube. It is a top sectional view showing a schematic structure of an external electrode type fluorescent lamp. It is a schematic diagram showing a bridge correction process according to a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,61 Fluorescent lamp 5,7,65,67 Electrode 11,69 Phosphor layer 20 Glass tube 22 Correction tool 24 Inner surface 52a, 52b, 56a, 56b Burner

Claims (9)

The glass tube is placed on a correction tool for correcting the glass tube so as to improve the straightness of the glass tube within a range of the sodium oxide content of 5 wt% or more and 20 wt% or less, and the glass tube is A correction process that rolls around the axis and corrects while heating,
Forming a phosphor layer on the inner surface of the glass tube after correction,
A method of manufacturing a fluorescent lamp, comprising performing a treatment for generating sodium sulfate on an outer peripheral surface of the glass tube by heating the glass tube in the presence of sulfurous acid gas and oxygen during the correcting step.   The correction tool is a cylindrical body that is held so that its axis is substantially horizontal, and the glass tube is placed on the inner surface of the correction tool, and the correction tool is rotated about its axis so as to be on the inner surface. 2. The method of manufacturing a fluorescent lamp according to claim 1, wherein the glass tube is rolled.   The said process is performed by filling the said correction tool in which the said glass tube was mounted in the said correction | amendment process with sulfurous acid gas and oxygen, and heating the said glass tube. Manufacturing method of fluorescent lamp.   2. The method of manufacturing a fluorescent lamp according to claim 1, wherein the treatment is performed by heating an outer peripheral surface of the glass tube in an atmosphere containing sulfurous acid gas and oxygen before the correction step.   The treatment is performed by blowing sulfurous acid gas from the crater of the burner to the outer peripheral surface while heating the outer peripheral surface of the glass tube with a burner in an oxygen-containing atmosphere before the correction step. The method for manufacturing a fluorescent lamp according to claim 1. An outer peripheral surface of the glass tube by heating the glass tube in the presence of sulfurous acid gas and oxygen while rotating a glass tube having a sodium oxide content of 5 wt% or more and 20 wt% or less around its axis. A sulfurous acid treatment step for generating sodium sulfate in
  A correction step of placing the glass tube on a correction tool for correcting the glass tube so as to improve the straightness of the glass tube after the sulfurous acid treatment, and correcting the glass tube by rolling while heating,
  And a forming step of forming a phosphor layer on the inner surface of the glass tube after correction. The glass tube is placed on a correction tool for correcting the glass tube so as to improve the straightness of the glass tube within a range of the sodium oxide content of 5 wt% or more and 20 wt% or less, and the glass tube is Including a straightening process of rolling around the axis and straightening while heating,
A method for producing a glass tube for a fluorescent lamp, characterized in that, during the straightening step, the glass tube is heated in the presence of sulfurous acid gas and oxygen to produce sodium sulfate on the outer peripheral surface thereof.   The correction tool is a cylindrical body that is held so that its axis is substantially horizontal, and the glass tube is placed on the inner surface of the correction tool, and the correction tool is rotated about its axis so as to be on the inner surface. 8. The method for producing a glass tube for a fluorescent lamp according to claim 7, wherein the glass tube is rolled. An outer peripheral surface of the glass tube by heating the glass tube in the presence of sulfurous acid gas and oxygen while rotating a glass tube having a sodium oxide content of 5 wt% or more and 20 wt% or less around its axis. A sulfurous acid treatment step for generating sodium sulfate in
A correcting step of placing the glass tube on a correction tool for correcting the glass tube so as to improve the straightness of the glass tube after the sulfurous acid treatment and correcting the glass tube by rolling while heating the glass tube. A method for producing a glass tube for a fluorescent lamp, comprising:

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