JP2010251243A - Fluorescent lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorescent lamp having a high-watt-type planar double spiral shape and a good manufacturing yield. <P>SOLUTION: The fluorescent lamp includes a planar-double-spiral-shape light emitting tube having a discharge path formed between a pair of electrodes which is arranged at both ends of the tube, the discharge path being folded back around a tube center portion at a pair of bent portions extending from both sides of the tube center portion and then spirally turned approximately in one plane at a pair of turn portions extending from the pair of bent portions. Its rated lamp electric power exceeds 25W, and the light emitting tube satisfies a relationship of 0.6≤B/A≤0.95 between a tube outer diameter A of the widest portion of the turn portion and a tube outer diameter B of the narrowest portion of the bent portion in view from the direction perpendicular to the plane. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  According to the present invention, a pair of electrodes are disposed at both ends of the tube, and a discharge path formed between the pair of electrodes extends from both sides of the tube central portion around the tube central portion. So-called plane double spiral fluorescent lamps having a planar double spiral shaped arc tube that spirally swivels substantially in one plane in a pair of swivel portions that are respectively extended at the pair of bent portions. Regarding lamps.

  The flat double spiral fluorescent lamp (double spiral lamp) is thin because the arc tube has a substantially disk shape. Therefore, the lamp can be designed to be thin, and it is suitable as a light source for downlights and wall lights attached to a ceiling or a wall. Moreover, since it becomes a surface light source which has a circular light emission surface, a light distribution characteristic is preferable and it is suitable for the illumination of a store or a house. As such a double spiral lamp, a low wattage type of 15 W or 20 W is known (Patent Document 1).

JP 2008-198493 A

  The double spiral lamp having the above-described features is not limited to the low wattage type, and it is desirable to increase the wattage and use it for wider applications. Therefore, when trying to increase the wattage of the double spiral lamp, problems specific to the high wattage type in terms of production yield were revealed. Specifically, there has been a problem that the production yield is reduced due to the peeling of the phosphor layer at the bent portion and the appearance defect at the swivel portion.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a fluorescent lamp having a high manufacturing yield while being a high watt type planar double spiral.

  In order to achieve the above object, a fluorescent lamp according to the present invention has a pair of electrodes arranged at both tube ends, and a discharge path formed between the pair of electrodes is centered on the tube center. A flat double spiral arc tube that is folded back by a pair of bent portions extending on both sides of the portion, and then swirls substantially in one plane in a pair of swiveling portions respectively extended to the pair of bent portions. The rated lamp power exceeds 25 W, and when the arc tube is viewed from the direction orthogonal to the plane, the tube outer diameter A of the thickest part in the swivel portion And the outer diameter B of the thinnest portion of the bent portion satisfy a relationship of 0.6 ≦ B / A ≦ 0.95.

  In the fluorescent lamp according to the present invention, the tube outer diameter A of the thickest portion in the swivel portion and the tube outer diameter B of the thinnest portion in the bent portion satisfy the relationship of 0.6 ≦ B / A. Product defects due to peeling are unlikely to occur and the manufacturing yield is high. In addition, since the tube outer diameter A and the tube outer diameter B satisfy the relationship of B / A ≦ 0.95, a product defect due to a defective appearance of the swivel portion of the arc tube hardly occurs, and the manufacturing yield is high.

1 is a perspective view showing a fluorescent lamp according to an embodiment of the present invention. It is a figure which shows the fluorescent lamp which concerns on one Embodiment of this invention, Comprising: (a) is a top view, (b) is a bottom view, (c) is a front view, (d) is a side view. It is a figure which shows the arc tube before a holder attachment, Comprising: (a) is a partially broken plan view, (b) is a front view Cross-sectional arrow view along line CC in FIG. It is a figure for demonstrating the whole flow of arc tube main body production, (a) is a figure which shows the glass tube before a process, (b) is a figure which shows an intermediate body, (c) shows an arc tube main body. Figure It is a figure for demonstrating a winding process, Comprising: (a) is a figure which shows the step which attaches a shaping | molding jig to a drive device, (b) is a figure which shows the step which winds a glass tube around a shaping | molding jig, (c) Figure shows the step of removing the glass tube from the forming jig Plan view showing the forming jig It is a figure for demonstrating a flattening process, Comprising: (a) is a figure which shows the step which installs an intermediate body in a deformation | transformation apparatus, (b) is a figure which shows the step which heats an intermediate body, (c) is intermediate | middle The figure which shows the step which deforms by applying pressure to the body The figure which shows the relationship between the value of B / A, and the fall of the manufacturing yield by peeling of a fluorescent substance layer The figure which shows the relationship between the value of B / A, and the fall of the manufacturing yield by the external appearance defect of a turning part.

Hereinafter, fluorescent lamps according to embodiments of the present invention will be described with reference to the drawings.
[Description of fluorescent lamp]
FIG. 1 is a perspective view showing a fluorescent lamp according to an embodiment of the present invention. FIG. 2 is a view showing a fluorescent lamp according to an embodiment of the present invention, in which (a) is a plan view, (b) is a bottom view, (c) is a front view, and (d) is a side view. . As shown in FIGS. 1 and 2, the fluorescent lamp 1 according to the present embodiment is a so-called high watt type double spiral lamp having a rated lamp power exceeding 25 W, and includes an arc tube 10 and the arc tube 10. And a holder 20 for holding.

1. FIG. 3 is a view showing the arc tube before the holder is attached, in which (a) is a partially cutaway plan view and (b) is a front view. As shown in FIGS. 3 (a) and 3 (b), the arc tube 10 has a pair of electrodes 30a and 30b arranged at both tube ends 11a and 11b, and a discharge formed between the pair of electrodes 30a and 30b. A pair of roads that extend around the pair of bent portions 13a and 13b after the path is folded back by a pair of bent portions 13a and 13b extending on both sides of the tube center portion 12 with the tube center portion 12 as a center. In the swivel portions 14a and 14b, the tube end portions 11a and 11b are opposed to each other with the tube center portion 12 in between. A bulging portion 15 bulging to the opposite side (irradiation surface side) of the holder 20 is formed in the tube central portion 12 of the arc tube 10, and the bulging portion 15 becomes the coldest point when the lamp is lit. .

  FIG. 4 is a cross-sectional arrow view taken along the line CC in FIG. As shown in FIG. 4, the tube cross sections of the bent portions 13a and 13b of the arc tube 10 have a flat shape obtained by flattening a substantially circular shape into a substantially semicircular shape. When the arc tube 10 is viewed from a direction E perpendicular to the plane D (for example, when viewed in plan as shown in FIGS. 2A and 3A), the diameters of the turning portions 14a and 14b are the largest. The outer diameter A of the thick portion and the outer diameter B of the thinnest portion of the bent portions 13a and 13b satisfy the relationship of 0.6 ≦ B / A ≦ 0.95. In the present embodiment, the swivel portions 14a and 14b (portions excluding the tube end portions 11a and 11b, the tube center portion 12 and the bent portions 13a and 13b in the arc tube 10) have substantially the same tube outer diameter. The position of the pipe outer diameter A shown in FIG. 3A is an example, and is not limited to that position.

  The glass constituting the arc tube 10 is made of, for example, barium strontium silicate glass (soft glass having a softening point of 675 ° C.). Further, the inner surface of the arc tube 10 is made of a phosphor by a rare earth phosphor made of, for example, a red phosphor (Y2O3: Eu), a green phosphor (LaPO4: Ce, Tb), and a blue phosphor (BaMg2Al16O27: Eu, Mn). Layer 18 is formed.

  For example, 5 mg of mercury is sealed inside the arc tube 10, and argon gas as a buffer gas is sealed so as to have a sealing pressure of about 300 Pa. The mercury enclosed in the arc tube 10 may be, for example, zinc mercury and tin mercury, or amalgam such as bismuth / indium mercury in addition to mercury alone. The sealed gas may be a mixed gas such as argon, neon, or krypton.

  Returning to FIG. 3A, the electrode 30 a includes a tungsten filament coil 31 and a pair of lead wires 32 a and 32 b, and the filament coil 31 is accommodated inside the arc tube 10. The lead wires 32a and 32b are hermetically sealed to one tube end 11a by a bead glass mounting method. Further, an exhaust pipe 33 used when sealing the rare gas into the arc tube 10 is hermetically sealed at the tube end portion 11a with the tip portion sealed. An electrode 30b having the same configuration as that of the electrode 30a is hermetically sealed at the other tube end 11b, but the exhaust pipe 33 is not hermetically sealed.

  The size of the fluorescent lamp 1 tends to increase as the rated lamp power increases. When the rated lamp power exceeds 25 W and is 50 W or less (preferably 30 W or more and 50 W or less), the outer diameter L (see FIG. 3A) of the arc tube 10 is 130 to 200 mm, the tube length is 900 to 1600 mm, The distance between 30a and 30b is 860 to 1560 mm, the number of winding layers of each of the swivel portions 14a and 14b is 1.4 to 2.1 times, the outer diameter of the tube is 10 to 13 mm, and the gap between adjacent tube walls is 5-9 mm.

When the rated lamp power is more than 50 W and less than 100 W, the outer diameter L of the arc tube 10 is 200 to 330 mm, the tube length is 1300 to 2600 mm, the distance between the electrodes 30a and 30b is 1250 to 2550 mm, The number of wound layers of each of the portions 14a and 14b is 1.4 to 2.1 times, the tube outer diameter is 18 to 22 mm, and the gap between adjacent tube walls is 5 to 9 mm.
When the rated lamp power is more than 100 W and not more than 150 W, the outer diameter L of the arc tube 10 is 360 to 450 mm, the tube length is 2800 to 3900 mm, the distance between the electrodes 30a and 30b is 2750 to 3850 mm, The number of wound layers of each of the portions 14a and 14b is 1.9 to 2.4 times, the tube outer diameter is 23 to 28 mm, and the gap between adjacent tube walls is 7 to 11 mm.

2. 1 and 2, the holder 20 includes a pair of bottomed cylindrical cap portions 21 a and 21 b that are externally fitted to the tube end portions 11 a and 11 b of the arc tube 10, and an irradiation surface of the arc tube 10. And a long plate-like connecting portion 22 that connects the pair of base portions 21a and 21b across the opposite side.
The base parts 21a and 21b are G type (for example, G5 type) bases that are electrically connected to a socket (not shown) on the lamp side to receive power supply, and their orientations are opposite to each other. Are disposed at both ends of the connecting portion 22 in the longitudinal direction, and a pair of pins 23a and 23b are provided on each bottom wall.

  The diameters of the cap portions 21a and 21b are larger than the tube outer diameters of the tube ends 11a and 11b of the arc tube 10, and the tube ends 11a and 11b of the arc tube 10 are inserted into the openings, respectively. The gap between the base parts 21a, 21b and the arc tube 10 is filled with an adhesive 24b (the adhesive on the base part 21a side is not shown), and the base parts 21a, 21b and the tube end parts 11a, 11b are connected. It is fixed. Moreover, as shown to Fig.2 (a), base part 21a, 21b and turning part 14a, 14b are also fixed by adhesive agent 25a, 25b. In addition, as these adhesive agent 24b, 25a, 25b, a silicone resin, an epoxy resin, an acrylic resin, cement etc. are used, for example.

[Method of manufacturing fluorescent lamp]
A method of manufacturing the fluorescent lamp 1 according to the embodiment of the present invention will be described with reference to the drawings. Here, only the process related to the shape of the bent portions 13a and 13b of the arc tube 10 will be described in detail, and the description of the other processes will be omitted or simplified.
5A and 5B are diagrams for explaining the overall flow of manufacturing the arc tube body, in which FIG. 5A is a diagram showing a glass tube before processing, FIG. 5B is a diagram showing an intermediate, and FIG. 5C is a light emission. It is a figure which shows a pipe | tube main body. In the arc tube 10, an intermediate body 200 having a substantially conical shape as shown in FIG. 5B is produced from a straight tubular glass tube 300 as shown in FIG. From FIG. 5C, a flat double spiral arc tube body 100 as shown in FIG. 5C is manufactured, and electrodes 30a and 30b are hermetically sealed on both tube ends 101a and 101b of the arc tube body 100 obtained. Produced.

  The glass tube 300 before processing has a substantially circular cross section, and as shown in FIG. 5A, end portions 301 a and 301 b that become the tube end portions 11 a and 11 b of the arc tube 10, and the arc tube 10. A tube center portion 302 that becomes the tube center portion 12, bend portions 303a and 303b that become the bent portions 13a and 13b of the arc tube 10, swivel portions 304a and 304b that become the swivel portions 14a and 14b of the arc tube 10, and a glass tube It comprises removal sections 305a and 305b that are removed after 300 windings.

6A and 6B are diagrams for explaining the winding process, in which FIG. 6A shows a step of attaching the forming jig to the driving device, and FIG. 6B shows a step of winding the glass tube around the forming jig. (C) is a figure which shows the step which removes a glass tube from a shaping | molding jig. FIG. 7 is a plan view showing a forming jig.
In the winding process for producing the intermediate body 200 from the glass tube 300, a forming jig 400 as shown in FIGS. 6A and 7 is used. The forming jig 400 has a substantially conical shape in appearance, and a pair of opposing locking portions 401a and 401b are provided near the top. Further, an intermediate point is located between the locking portions 401a and 401b on the weight surface of the forming jig 400, and both sides of the intermediate point are folded back by the locking portions 401a and 401b, respectively. A guide groove 402 having a shape spirally turned around F as a rotation axis is formed.

  In the winding process, first, the glass tube 300 is heated and softened in a heating furnace or the like. Next, in the state where the tube center portion 302 of the glass tube 300 is disposed between the locking portions 401a and 401b of the forming jig 400 and the removing portions 305a and 305b are held movably, the forming treatment is performed by the driving force of the driving device. The tool 400 is rotated in the direction indicated by the arrow G, and is also raised at the same time, so that the swivel portions 304 a and 304 b are wound up in a double spiral shape along the guide groove 402. At that time, pressure-controlled air in the glass tube 300 is formed in order to prevent the swiveling portions 304a and 304b from being flattened and to bulge the irradiation surface side of the tube central portion 302 to form a bulging portion 205 described later. A gas such as nitrogen or argon is blown.

The bent portions 303a and 303b of the glass tube 300 are bent by engaging with the engaging portions 401a and 401b of the forming jig 400, and the tube cross section is deformed from a substantially circular shape to a flat shape (flattened). The flat shape is maintained even after the subsequent steps, and the tube cross sections of the bent portions 13a and 13b of the arc tube 10 are also substantially flat.
Since the bent portions 303a and 303b become a part of the discharge path when the lamp is used, the cross-sectional area is preferably large. However, if the cross-sectional areas of the bent portions 303a and 303b are increased, the cross-sectional areas of the swivel portions 304a and 304b that are close to the bent portions 303a and 303b also increase. That is, in the swivel portions 304a and 304b, the outer diameters of the pipes are not uniform, resulting in poor appearance. In order to prevent such an appearance defect, it is necessary to control the flattening of the bent portions 303a and 303b so that the B / A value in the arc tube 10 is 0.95 or less. The flattening can be controlled by adjusting the heating temperature of the glass tube 300 and the amount of gas blown in the winding step.

After the temperature is lowered and the glass tube 300 is cured, as shown in FIG. 6C, the glass tube 300 is removed from the forming jig 400, and the removal portions 305a and 305b are removed to complete the intermediate body 200. Let
Next, a phosphor suspension is poured into the intermediate 200 and a phosphor suspension is applied to the inner surface to form the phosphor layer 18. Since the bent portions 303a and 303b have a flat tube cross section and are further folded, the flow of the phosphor suspension is poor, and if the flow is poor, the phosphor suspension adheres excessively to the inner surface. The phosphor layer 18 becomes thicker than necessary only in that portion. In particular, the portions where the radius of curvature R above and below the corners of the bent portions 303a and 303b is large (the portions indicated by reference numerals 19a and 19b in FIG. 4 in the bent portions 13a and 13b after the arc tube 10 is completed) are phosphor suspended. The liquid adheres excessively and the phosphor layer tends to be thick. In this way, the portion where the phosphor layer 18 is thick is likely to be peeled off in the flattening step described later.

  In particular, when the fluorescent lamp 1 is a high watt type, since the outer diameter of the arc tube 10 is large, the shapes of the bent portions 13a and 13b are difficult to stabilize, and the phosphor layer becomes thicker at the bent portions 303a and 303b, resulting in peeling. easy. In order to prevent this, it is necessary to control the flattening of the bent portions 303a and 303b so that the value of B / A in the arc tube 10 is 0.6 or more. As described above, the flattening can be controlled.

FIGS. 8A and 8B are diagrams for explaining the flattening process, in which FIG. 8A shows a step of installing the intermediate body in the deformation device, FIG. 8B shows a step of heating the intermediate body, (c) is a figure which shows the step which applies a pressure to an intermediate body and deform | transforms.
In the flattening step, the intermediate body 200 is heated again, and is then deformed by applying pressure, so that it is deformed from a substantially cone shape in appearance to a substantially disk shape in appearance as shown in FIG. The flattening process is performed using a deformation device 420 as shown in FIG. The deformation device 420 includes a movable plate 421, a fixed plate 422, a plurality of guide bars 423, and a plurality of regulating members 424.

  The movable plate 421 and the fixed plate 422 are made of, for example, stainless steel, and are opposed to each other up and down with the intermediate body 200 interposed therebetween. The movable plate 421 can move up and down while maintaining a state substantially parallel to the fixed plate 422. The movable plate 421 is formed with a through-hole 425 in the approximate center of the movable plate 421 so that the bulging portion 205 of the intermediate body 200 that will later become the bulging portion 15 of the arc tube 10 can be accommodated.

The guide bar 423 is erected on the upper surface of the fixed plate 422 and passes through a hole (not shown) of the movable plate 421. The restricting members 424 are disposed at the four corners of the upper surface of the fixed plate 422 and restrict the movable plate 421 from being too close to the fixed plate 422.
First, as illustrated in FIG. 8A, the intermediate body 200 is disposed between the movable plate 421 and the fixed plate 422. The intermediate body 200 is disposed at a position approximately at the center of the upper surface of the fixed plate 422, and the bulging portion 205 of the intermediate body 200 is directly below the through hole 425 of the movable plate 421. At this time, the periphery of the through hole 425 in the movable plate 421 is in contact with a part of the turning portions 204 a and 204 b of the intermediate body 200.

  Next, as shown in FIG. 8B, the intermediate 200 is heated. The heating temperature is a temperature at which the phosphor layer 18 applied to the inner surface of the intermediate body 200 can be baked, whereby the phosphor layer 18 on the inner surface of the intermediate body 200 is baked. Further, the heated intermediate body 200 can be plastically deformed, and the movable plate 421 starts to descend due to its own weight. That is, the swivel portions 204a and 204b of the intermediate body 200 are compressed in the vertical direction and begin to deform. The lowering of the movable plate 421 stops when the movable plate 421 comes into contact with the regulating member 424.

As described above, in the flattening process, the phosphor layer 18 is baked and the intermediate body 200 is deformed. When the phosphor layer 18 is formed to be thicker than necessary, the baked phosphor layer 18 is formed. However, there is a risk of peeling from the inner surface due to deformation of the intermediate body 200.
The heating temperature is preferably set lower than the softening point of glass (soft glass). When the temperature of the intermediate body 200 is equal to or higher than the softening point, the glass is deformed by its own weight, so that it is difficult to maintain the shape of the intermediate body 200. Further, when the temperature is raised to the vicinity of the softening point of the glass, there arises a problem that the peeling of the phosphor layer 18 formed on the inner surface of the intermediate 200 becomes more severe.

As shown in FIG. 8C, when the movable plate 421 comes into contact with the regulating member 424, the deformation of the intermediate body 200 into the arc tube main body 100 is completed.
Next, the electrodes 30 a and 30 b are sealed to the arc tube main body 100. Specifically, the electrode 30a and the exhaust pipe 33 are inserted into the tube end portion 101a of the arc tube main body 100, the electrode 30b is inserted into the tube end portion 101b, and the tube end portions 101a and 101b are heated and softened by a burner, and then pinched. Crush and heat the softened areas with a block.

  The holder 20 is attached to the arc tube 10 thus manufactured, and the fluorescent lamp 1 is completed. The holder 20 inserts the tube end portions 11a and 11b of the arc tube 10 into the openings of the base portions 21a and 21b, and fixes the adhesive 24b by pouring the adhesive 24b into the gap between the base portions 21a and 21b and the tube end portions 11a and 11b. . Finally, the lead wires 32a and 32b and the pins 23a and 23b are electrically connected.

[Yield evaluation]
FIG. 9 is a diagram showing the relationship between the value of B / A and the decrease in manufacturing yield due to the peeling of the phosphor layer. As shown in FIG. 9, a low watt type fluorescent lamp (rated lamp power of 7 W or more and 25 W or less) having a tube outer diameter of 9 mm of the swivel parts 14a and 14b, and a high watt type fluorescent lamp having a tube outer diameter of 12 mm ( A rated lamp power exceeding 25 W and 50 W or less, preferably 30 W or more and 50 W or less), a high watt type fluorescent lamp having a tube outer diameter of 20 mm (rated lamp power exceeding 50 W and 100 W or less), and a tube outer diameter of 25.5 mm. For each of the high watt type fluorescent lamps (more than the rated lamp power of 100 W and 150 W or less), various fluorescent lamps having different B / A values were produced, and the product yield regarding the phosphor layer peeling was evaluated.
In the evaluation of the production yield, the presence or absence of peeling of the phosphor layer on the inner surface of the bent portion was observed. The yield rate was determined. Specifically, the degree of peeling determined to be a defective product is a case where peeling of width 1 mm × length 3 mm or more has occurred.

  As a result of the evaluation, it was found that in the case of a high watt type fluorescent lamp, if the relationship of 0.6 ≦ B / A is satisfied, the product yield is 90% or more, and the phosphor layer is hardly peeled off. On the other hand, in the case of a low-wattage type fluorescent lamp, the production yield may be 90% or more even if the relationship of 0.6 ≦ B / A is not satisfied (even when B / A = 0.56). It was found that the relationship of 0.6 ≦ B / A is not necessarily satisfied as in the watt type fluorescent lamp 1.

FIG. 10 is a diagram illustrating a relationship between the value of B / A and a decrease in manufacturing yield due to poor appearance of the swivel unit. Similar to the evaluation of the production yield by peeling off the phosphor layer, various fluorescent lamps having different B / A values were produced for each of the fluorescent lamps having tube outer diameters of 9 mm, 12 mm, 20 mm and 25.5 mm. The product yield concerning the appearance defect of the turning part was evaluated.
In the evaluation of the production yield, the appearance of the swivel part is observed in a plan view, and a product with a good appearance is judged as a non-defective product and a product with a poor appearance is judged as a defective product. ", The case of less than 90% was taken as" x ". It should be noted that an appearance defect was particularly likely to occur in a region within one turn from the bent portion of the turning portion. Explaining in detail the degree of appearance failure, the maximum value of the pipe outer diameter in the region within one turn from the bent part of the swivel parts 304a and 304b is 1. This is a case of 2 times or more.

As a result of the evaluation, in the case of a high watt type fluorescent lamp, it is found that if the relationship of B / A ≦ 0.95 is satisfied, the product yield is 95% or more, and the product defect due to the appearance defect of the swivel part is difficult to occur. It was.
[Modification]
Although the fluorescent lamp according to the present invention has been specifically described above based on the embodiment, the contents of the present invention are not limited to the above-described embodiment. For example, the arc tube may not necessarily be held by a holder, and a configuration in which only a base is attached to both ends of the arc tube without the holder may be employed. Further, the external shape of the arc tube is not limited to a circular spiral shape in a plan view, and may be, for example, a polygonal spiral shape such as a quadrangle in a plan view.

  INDUSTRIAL APPLICABILITY The fluorescent lamp of the present invention can be used for a fluorescent lamp provided with a flat double spiral arc tube whose discharge path swirls substantially in one plane around the center of the tube.

1 fluorescent lamp 10 arc tube 11a, 11b tube end
12 Tube central part 13a, 13b Bent part 14a, 14b Swivel part 30a, 30b Electrode

Claims (4)

A pair of electrodes are arranged at both ends of the tube, and a discharge path formed between the pair of electrodes is folded back by a pair of bent portions extending on both sides of the tube center portion with the tube center portion as a center. A fluorescent lamp comprising a planar double spiral arc tube that spirally swivels substantially in one plane in a pair of swivel portions respectively extending to the pair of bent portions;
When the rated lamp power exceeds 25 W and the arc tube is viewed from the direction orthogonal to the plane, the tube outer diameter A of the thickest part in the swivel part and the thinnest part of the bent part A fluorescent lamp characterized in that a tube outer diameter B satisfies a relationship of 0.6 ≦ B / A ≦ 0.95.   2. The fluorescent lamp according to claim 1, wherein a tube length of the arc tube is 900 to 1600 mm, and an outer diameter of the tube at the pair of turning portions is 10 to 13 mm. 2. The fluorescent lamp according to claim 1, wherein a tube length of the arc tube is 1300 to 2600 mm, and an outer diameter of the tube at the pair of swivel portions is 18 to 22 mm. 2. The fluorescent lamp according to claim 1, wherein a tube length of the arc tube is 2800 to 3900 mm, and a tube outer diameter of the pair of swivel portions is 23 to 28 mm.

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