JP2005078927A - Fluorescent lamp and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fluorescent lamp which can maintain high luminous efficiency and can suppress cracks and peeling at a bending portion and its manufacturing method. <P>SOLUTION: The fluorescent lamp is composed of a bulb made to have a curved part of which centers of curvatures of an inside face and an out side face coincide with each other, and the diameter is nearly same as that of a straight part, by heating and bending a part to be bent of a straight-tube shaped bulb, having electrodes at both ends so as to form a discharge path through the straight part and the curved part, in which, a discharging medium containing mercury is sealed, a phosphor layer which is formed on the inner face of the bulb and of which the coating amount at the bending part is smaller than that at the the straight tube part, and bases provided at both ends of the bulb. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fluorescent lamp and a method for manufacturing the same, and more particularly, to a fluorescent lamp having a phosphor layer characterized in that the amount of phosphor attached to a bent portion is smaller than that of a straight tube and a method for manufacturing the same.

  As a fluorescent lamp for general illumination, a straight tube type, a ring shape, or a single-piece type fluorescent lamp is known. Particularly, based on recent demands for energy saving and resource saving, the outer diameter of the tube is 15 to 18 mm, and it is dedicated for high frequency lighting. Have been commercialized (see Patent Document 1). This small-diameter annular fluorescent lamp is identified by the model name “FHC” on the commodity. This small-diameter annular fluorescent lamp has the same outer diameter as that of the conventional annular fluorescent lamp, but the outer diameter of the tube is small, and it is possible to ensure the same or higher efficiency or brightness. It is possible to satisfy the resource saving needs and to make the visual environment particularly comfortable in the living space.

Further, a fluorescent lamp is known in which a single straight tube bulb is partially bent so that all straight tube portions form a substantially square shape within the same plane (see Patent Document 2). .
Japanese Patent No. 3055769 (page 5-7, FIG. 3) Japanese Examined Patent Publication No. 3-59548 (column 5, FIG. 1)

  However, in the thin annular fluorescent lamp of Patent Document 1, after forming a protective film and a phosphor layer on a straight tube bulb, electrodes are sealed at both ends and heated so that the entire straight tube bulb is softened. Therefore, the initial luminous flux tends to decrease due to thermal deterioration of the phosphor layer. In addition, the alkali component in the bulb is precipitated by the heating process, reacts with the phosphor layer, is likely to deteriorate with time, and the luminous flux maintenance factor is liable to decrease.

  Furthermore, since the small diameter annular fluorescent lamp is polarized while the straight tube bulb is stretched in the longitudinal direction, the protective film and phosphor layer formed on the straight tube bulb are likely to crack when bent, and the protective film and There is a problem that the body layer cannot be thickened. For this reason, there has been a limit to improving the initial luminous flux by increasing the thickness of the phosphor layer and improving the luminous flux maintenance factor by increasing the thickness of the protective film.

  In this respect, since the fluorescent lamp of Patent Document 2 is partially bent, thermal degradation of the phosphor layer in the straight tube portion that is not bent is small.

  However, the fluorescent lamp of Patent Document 2 has a bent portion with a smaller radius of curvature than an annular fluorescent lamp, and cracking or peeling occurs when the phosphor layer formed on the inner surface of the bulb is made thicker in order to increase luminous efficiency. If the phosphor layer is made thin so as not to crack or peel off at the bent portion, the luminous efficiency in the straight tube portion cannot be increased, and the advantage of providing the straight tube portion is lost.

  In addition, a technique of mixing a binder made of an inorganic material in order to prevent cracking and peeling is also known, but if this is added too much, there is a problem that the luminous efficiency is lowered, which solves the above problem. I couldn't.

  Therefore, the present invention has been made to solve this problem, and provides a fluorescent lamp capable of maintaining high luminous efficiency and suppressing cracking and peeling at a bent portion, and a method for manufacturing the same. For the purpose.

  In the fluorescent lamp according to claim 1, by heating and bending the bent portion formation scheduled portion of the straight tubular bulb, the centers of the curvature radii of the inner side surface and the outer side surface are substantially at the same position and the tube diameters are adjacent to each other. Discharge medium containing mercury, forming bent portions that are substantially the same as the tube diameter of the straight tube portion, and having electrodes sealed at both ends so that one discharge path is formed through the straight tube portion and the bent portion. A fluorescent material layer formed on the inner surface of the bulb and having a smaller amount of fluorescent material attached to the bent portion than the straight tube portion; and caps provided at both ends of the bulb. It is characterized by.

  The valve is formed of a plurality of straight pipe portions and a bent portion that is sandwiched and communicated with the straight pipe portions, and the bent portion is formed by heating a bent portion forming scheduled portion of one straight tubular valve. It is formed by bending. Further, it may be formed by bending a plurality of straight tubular valves and connecting the ends. The bent portion may be formed by molding as well as a straight tubular valve simply bent.

  The bent part is formed so that the center of the radius of curvature of the inner side surface and the outer side surface of the bulb is substantially the same position, and “the center of the radius of curvature is substantially the same position” of this bent part is the curvature of the inner side surface of the bent part. It means that the center point of the radius and the center point of the radius of curvature of the outer surface overlap or are slightly displaced. In the operation of the present invention, if the distance between the center points is within 10% of the radius of curvature, more preferably within 5%, it is within the allowable range.

  The tube diameter of the bent portion is formed to be substantially the same as the tube diameter of the adjacent straight tube portion. The tube diameter of the bent portion is defined by the tube diameter in the valve tube cross section orthogonal to the direction of radiating in parallel along the same plane from the center point of the virtual annular plane formed by the annular valve. If it is slightly flat, it is defined by the average tube diameter. Here, “substantially the same” means that the tube diameter of the bent portion is within ± 10%, preferably within ± 5% of the tube diameter of the straight tube portion.

  The tube length of the straight tubular bulb is not particularly limited, but it is almost the discharge path length. Therefore, it is preferable that the tube length is in the range of 800 to 2500 mm in consideration of obtaining a light emission amount equivalent to that of a conventional small-diameter annular fluorescent lamp.

  The straight tube portion can have a tube inner diameter in the range of 12-30 mm, preferably in the range of 12-20 mm, and the optimal tube inner diameter in consideration of lamp characteristics such as lamp efficiency and manufacturing conditions. The range is 14-18 mm. Note that the straight pipe portion in the vicinity of the bent portion may slightly deviate from the above range due to a slight change in the outer diameter of the tube during the formation of the bent portion. It may be within the range. In addition, it is good for the thickness of a straight pipe part to be about 0.8-1.2 mm.

  In the present invention, the tube outer diameter of the straight tube portion is set to 30 mm or less including the fluorescent lamp that is widely used. However, it is known that the lamp efficiency of the fluorescent lamp is generally improved by reducing the tube diameter. In addition, it is preferable that the tube outer diameter of the straight tube portion is 20 mm or less because it is possible to achieve lamp efficiency equivalent to that of the small-diameter fluorescent lamp. On the other hand, when the tube outer diameter of the straight tube portion is less than 12 mm, it becomes difficult to ensure the mechanical strength as a glass bulb having a bent portion, and a light emission amount equivalent to that of a conventional annular fluorescent lamp of the same size is obtained. It is not practical because it is not possible.

  In order to improve the lamp efficiency of a conventional annular fluorescent lamp (model name “FCL”) having a tube outer diameter of 29 mm by 10% or more, it is necessary to reduce the tube outer diameter to 65% or less. That is, the pipe outer diameter of the straight pipe part may be 18 mm or less. With this tube outer diameter, the fluorescent lamp can be sufficiently thinned. In consideration of characteristics such as the light emission amount and lamp efficiency, it is preferable that the tube outer diameter of the straight tube portion is 14 mm or more.

  The valve has two or more straight pipe portions, and the bent portion connecting the straight pipe portions is formed so as to be one fewer than the straight pipe portions. The bent portion is bent so that the straight pipe portion is located on substantially the same plane.

  In the bulb, a plurality of straight pipe portions are connected to form one discharge path, which is formed by a pair of electrodes sealed at both ends, and the inside of the straight pipe portion is connected by a bent portion. Is. In addition, all the straight pipe parts do not need to have the same length, and only one or a plurality of lengths may be different.

  The phosphor layer is formed on the inner surface of the bulb, and is formed by applying a phosphor slurry comprising a phosphor, a binder that is a solvent thereof, a binder, and the like. This phosphor layer changes the amount of phosphor adhering at the bent part and straight pipe part, and the amount of adhering is reduced at the bent part so that the phosphor layer is not cracked or peeled off. In order to secure a sufficient amount of light emission, the amount of adhesion is increased to increase the film thickness, thereby improving the light emission efficiency of the entire fluorescent lamp.

The fluorescent lamp according to claim 2 is the fluorescent lamp according to claim 1 or 2, wherein the amount x of the fluorescent substance adhered per unit area in the bent portion is in the range of 3.5 to 5.5 mg / cm ^2. The fluorescent substance adhesion amount y per unit area in the tube part is in the range of 5.5 to 8.0 mg / cm ² .

The present invention specifically defines the amount of phosphor attached to the straight tube portion and the bent portion, and the emission peak of the phosphor is around 7.0 mg / cm ² in the straight tube portion. The amount can be secured very efficiently. Further, in the bent portion, the amount of light emission is ensured while efficiently suppressing cracking and peeling of the phosphor layer.

  According to a third aspect of the present invention, in the fluorescent lamp according to the first aspect, the ratio between the amount x of the fluorescent substance attached to the bent portion and the amount y of the fluorescent substance attached to the straight tube portion is 0.40 <x / y. <0.75 is satisfied.

  The present invention defines a preferable ratio of the amount of phosphor adhering between the bent portion and the straight tube portion, and the light emission between the straight tube portion and the bent portion is achieved by satisfying the relationship of the amount of phosphor adhered. The difference in the amount can be reduced, so that it is not felt that the bent portion is dark and only the straight tube portion emits light, and it can be felt that the entire fluorescent lamp is connected to emit light. Is.

  According to a fourth aspect of the present invention, in the fluorescent lamp according to any one of the first to third aspects, the length in the axial direction of the bulb of the portion where the amount of the phosphor adhering to the bent portion formation scheduled portion is small. The ratio between L and the radius of curvature R of the inner surface of the bent portion after bending the bent portion formation scheduled portion satisfies the relationship of 0.5 <L / R <5.0.

  The present invention relates to the length in the axial direction of the bulb of the phosphor layer with a small amount of phosphor adhering to the bent portion formation planned portion, and the radius of curvature of the inner surface of the bent portion obtained by bending the bent portion formation planned portion. The radius of curvature of the inner surface changes depending on the bending method of the bent portion, and when this radius of curvature is small, the length of the phosphor layer with a small amount of phosphor adhered When the radius of curvature of the inner surface of the bent portion is large, it is necessary to increase the length of the phosphor layer with a small amount of phosphor adhering. That is, according to the present invention, the length of the phosphor layer formed in the bent portion formation scheduled portion is determined in a necessary and sufficient range, and is long enough to suppress cracking and peeling of the phosphor layer in the bent portion. Therefore, a phosphor layer with a small amount of phosphor adhering to the straight tube portion is not formed unnecessarily, so that the light emission amount in the straight tube portion can be efficiently ensured.

  The fluorescent lamp according to claim 5 is the fluorescent lamp according to any one of claims 1 to 4, characterized in that the bulb is annular.

  In the present invention, the bulb of the fluorescent lamp has an annular shape, and the shape thereof can be formed as a polygonal shape composed of a straight tube portion such as a triangle or a quadrangle and a bent portion.

  This annular valve has three or more straight pipe portions, and the bent portion connecting the straight pipe portions is one less than the straight pipe portions so that the straight pipe portions are positioned substantially on the same plane. It is formed by bending. This annular valve is formed so that electrodes are sealed at the ends where the bent portions of the straight pipe portions located on both sides are not connected, and the pair of ends are opposed to each other. Here, “a pair of end portions oppose each other” is a form in which the tube axes of the straight tube portions constituting the valve end portions are positioned on the same axis and the end surfaces of the valve end portions face each other. In addition, the end surfaces are not facing each other, but the end surfaces are at an angle so that the angle formed by the tube axes of the straight tube portions constituting each valve end portion is approximately 90 °. You may be facing.

  The annular bulb forms a single discharge path that surrounds the approximate center of the arrangement relationship of the plurality of straight tube portions, and the inside of the tube of the straight tube portion is connected by a bent portion and sealed at both ends. One discharge path is formed by a pair of electrodes. In addition, all the straight pipe parts do not need to have the same length, and only one or a plurality of lengths may be different. When four straight pipe portions having substantially the same tube length are formed by three bent portions, the valve forms a substantially square shape by the straight pipe portions.

  The method of manufacturing a fluorescent lamp according to claim 6 includes: a first phosphor layer forming step of forming a first phosphor layer having a uniform thickness on the inner surface of the straight tube bulb; A phosphor layer removing step of removing the phosphor layer at a bent portion formation scheduled portion of the straight tubular bulb among the body layers; and a second phosphor layer having a uniform thickness on the inner surface of the straight tubular bulb. 2) a phosphor layer forming step; and by bending the bent portion forming scheduled portion with a small amount of phosphor adhering among the phosphor layers having different thicknesses formed by these steps, And a bent portion forming step for forming the structure.

  The present invention relates to a method of manufacturing a fluorescent lamp having a straight tube portion and a bent portion, and the amount of phosphor deposited on the inner surface of the straight tube bulb is large in the straight tube portion and less in the bent portion formation scheduled portion. Manufacturing a fluorescent lamp that can secure a sufficient amount of light emission in the straight tube part by bending, and can suppress the occurrence of cracking and peeling of the phosphor layer even if it is bent in the bent part. To do.

  The difference in the adhesion amount of this phosphor is that once the phosphor layer is formed on the entire inner surface of the straight tubular bulb, and this is removed at the portion where the bent portion is to be formed, a difference is provided in the adhesion amount, and further the straight tubular bulb By forming the phosphor layer on the entire inner surface, two phosphor layers are laminated in the straight tube portion, and one phosphor layer is formed in the bent portion formation scheduled portion.

  The fluorescent lamp manufacturing method according to claim 7 is the fluorescent lamp manufacturing method according to claim 6, wherein the phosphor layer removing step heats the phosphor layer of the bent portion formation scheduled portion from the outside of the bulb. After the binder in the layer is removed by incineration, the fluorescent material in the bent formation scheduled portion is removed by blowing compressed air.

  In order to remove the first phosphor layer on the inner surface of the straight tubular bulb, the present invention can be performed by a simple operation of heating from the outside of the straight tubular bulb and blowing compressed air onto the inner surface. .

  According to the fluorescent lamp of claim 1, since the bent portion is formed in this way, the outer appearance of the bent portion of the bulb is visually recognized as being configured to draw a continuous curve from the straight pipe portion. The appearance of the tube is improved, and the part where the temperature is locally low is not formed at the time of lighting, so it is difficult to form the coldest part, and the bent part is less likely to be blackened or stained with agglomerated mercury. Since the amount of phosphor adhering is less than that of the straight tube part, it is possible to prevent the phosphor layer of the bent part from cracking or peeling off when bending by heating, and the fluorescent light in the straight tube part. Since the adhesion amount of the body is large, a sufficient amount of light emission can be secured, so that the light emission efficiency can be kept high.

  According to the fluorescent lamp of claim 2, the amount of the fluorescent substance attached to the bent portion is an amount capable of suppressing cracking and peeling of the fluorescent substance layer and ensuring the light emission amount. Since the adhesion amount of the body is an amount in the vicinity of the peak of the luminous efficiency, the effect of the invention described in claim 1 can be exhibited more preferably.

  According to the fluorescent lamp of claim 3, there is a fixed relationship between the amount of phosphor attached to the bent portion and the amount of phosphor attached to the straight tube portion, and there is a difference in light emission amount between the straight tube portion and the bent portion. Since it is small, it can be made excellent in appearance during use.

  According to the fluorescent lamp of claim 4, the length of the portion with a small amount of phosphor adhering in the bent portion is not formed in an appropriate range, that is, unnecessarily in the straight tube portion, and in the bent portion. Since it can form in the range which can fully suppress the crack and peeling of a fluorescent substance layer, the effect of the invention described in Claim 1 can be exhibited in a very preferable state.

  According to the fluorescent lamp of claim 5, by making the bulb annular, it is possible to obtain a fluorescent lamp having a large light emitting area with a single bulb, and it is necessary to mount a plurality of conventional straight-ring fluorescent lamps. Since it is sufficient to mount one fluorescent lamp on the lighting fixture, the efficiency of the lamp can be improved as a result.

  According to the method for manufacturing a fluorescent lamp of claim 6, after forming the first phosphor layer, only the phosphor layer in the bent portion formation scheduled portion is removed, and then the second phosphor layer is formed. A phosphor with a large amount of phosphor adhering to the straight tube portion where the first phosphor layer remains, and a phosphor with a small amount of phosphor adhering to the bent portion formation planned portion from which the first phosphor layer has been removed A layer can be formed, and the fluorescent lamp according to claims 1 to 5 can be easily manufactured.

  According to the method for manufacturing a fluorescent lamp of claim 7, the first phosphor layer is removed by heating from the outside of the bulb to remove the binder, and then the phosphor removed by the binder removal is compressed air. By blowing off, the phosphor layer at the bent portion formation scheduled portion can be easily removed, and the fluorescent lamp according to any one of claims 1 to 5 can be manufactured more easily.

  Hereinafter, embodiments of the fluorescent lamp of the present invention will be described with reference to the drawings. 1 to 3 show a first embodiment of the present invention, FIG. 1 is a front view of a fluorescent lamp, and FIG. 2 is a straight tubular bulb for explaining the production of a straight tubular bulb used for manufacturing the fluorescent lamp of FIG. FIG. 3 is a schematic view for explaining a manufacturing process of the fluorescent lamp of FIG. 1.

  In FIG. 1, reference numeral 1 denotes a fluorescent lamp, which has a rectangular annular glass bulb 2 in which a straight portion forms a substantially square shape. The annular glass bulb 2 is filled with a discharge medium composed of a rare gas such as argon, neon or krypton and mercury. The rare gas in this embodiment is argon (Ar) gas, and the sealing pressure is about 320 Pa.

  The annular glass bulb 2 has four straight pipe portions 2b and three bent portions 2c, and the four straight pipe portions 2b are connected and arranged in the same plane so as to form substantially square sides. Has been. At this time, the length of one side of the glass bulb 2 is preferably 200 mm or more. In the present embodiment, the length of one side is about 300 mm. The straight pipe portion 2b preferably has a pipe outer diameter of 12 to 30 mm and a wall thickness of 0.8 to 1.5 mm. In this embodiment, the pipe inner diameter is about 14 mm and the wall thickness is about 1.2 mm. .

  The bulb 2 is preferably made of soft glass such as soda lime glass or lead glass, but may be made of hard glass such as borosilicate glass or quartz glass.

On the inner surface of the glass bulb 2, fine particles of a metal oxide such as alumina (Al ₂ O ₃ ) and silica (SiO ₂ ) or an alkaline earth metal phosphate such as strontium phosphate (Sr ₂ P ₂ O ₇ ) are used. A protective film 3 is formed, and the fine particles having an average particle diameter of 10 nm to 10 μm can be used, and preferably 10 to 100 nm. When fine particles having an average particle diameter of 10 to 100 nm are used, the fine particles are difficult to sink into the glass when the bent portion is formed, and the fine particles move together with the glass surface when the bulb 2a is bent. It is possible to suppress the occurrence of cracks and peeling. The phosphor layer 4 is formed on the inner surface of the protective film 3, and if problems such as the luminous flux maintenance factor and film peeling at the time of bulb processing do not become a problem, the bulb 2 can be formed without interposing the protective film. Although the phosphor layer 4 can be directly formed on the inner surface, it is preferable to provide a protective film from the viewpoint of effectively preventing this problem. The coating amount of the protective film is 0.01~0.8mg / cm ^2, is preferably at least 0.1 mg / cm ² or more over the entire fluorescent lamp.

The phosphor layer 4 is applied and formed on the inner surface of the straight tubular bulb 2 before forming the bent portion. The phosphor constituting the phosphor layer 4 can be composed of a well-known phosphor such as a three-wavelength phosphor or a halophosphate phosphor, and the use of a three-wavelength phosphor is preferable from the viewpoint of luminous efficiency. . As the phosphor of the three-wavelength emission type, BaMg ₂ Al ₁₆ O ₂₇ : Eu ²⁺ as a blue phosphor having an emission peak wavelength near 450 nm, and (La, Ce) as a green phosphor having an emission peak wavelength near 540 nm. , Tb) PO ₄ , Y ₂ O ₃ : Eu ³⁺ can be applied as a red phosphor having an emission peak wavelength near 610 nm, but is not limited thereto.

In the present embodiment, the phosphor layer 4 is a three-wavelength emission type phosphor fine particle having a correlated color temperature of 5000 K within the range of 5.5 to 8.0 mg / cm ² in the straight tube portion and in the bent portion. Is applied in the range of 3.5 to 5.5 mg / cm ² and formed through a drying and firing process. In addition, the film thickness at this time is about 15-30 micrometers in a straight pipe part, and is about 10-15 micrometers in a bending part. In the present embodiment, the amount of the phosphor layer deposited is 7.0 mg / cm ² at the straight tube portion and 3.8 mg / cm ² at the bent portion.

  Both end portions 2d of the glass bulb 2 are arranged close to each other, and filament electrodes 5 and 5 made of a triple coil coated with an emitter material are respectively sealed at both end portions 2d. The pair of electrodes 5 and 5 are supported by a pair of lead wires sealed to a flare stem (not shown), and the filament electrodes 5 and 5 are sealed in the bulb by sealing the flare stem to both ends 2d. The An exhaust thin tube 2f is attached to the flare stem, and amalgam 2g is accommodated in the thin tube 2f.

  The amalgam 2g is sealed in the valve, and the arrangement position is not limited to the exhaust thin tube 2f, but may be fixed to, for example, a welded portion of the flare stem. The amalgam is fixed or stored in any one of these positions by means such as melting and mechanical holding. Moreover, the amalgam may be accommodated so as to be movable in the bulb, and for example, the inner surface portion of the bulb 2 where the phosphor layer 4 is formed may be enclosed so as to be movable.

  Amalgam is an alloy of mercury and a substance that forms an alloy with mercury, and may have any shape such as pellets, columns, and plates. For example, an amalgam such as zinc-mercury may be encapsulated for quantitative encapsulation of mercury. When an amalgam for controlling the mercury vapor pressure is disposed in the bulb, the fluorescent lamp is lit in an optimum state even when the ambient temperature is relatively high. The amalgam 2g of this embodiment is a bismuth (Bi) -tin (Sn) -lead (Pb) -based mercury vapor pressure control amalgam.

  The inside of the straight tube portion 2b is communicated via the bent portion 2c, and a single discharge path is formed between the pair of electrodes 5 and 5 so as to surround a substantially square center formed by the straight tube portion 2b. The

  As the pair of electrodes 5 and 5, a hot cathode type electrode in which an emitter material is applied to a filament is applicable, but other electrodes may be used. When it is necessary to light the lamp at a high output, it is preferable to use a triple coil for the hot cathode electrode 5. The lead wire that supports the electrode 5 may be sealed and supported by a button stem, a bead stem, a pinch seal portion, or the like.

  The bent part 2c has a substantially circular cross-sectional shape that is substantially the same as that of the straight pipe part 2b. The bent portion 2c is formed so that the centers of the radii of curvature of the inner surface and the outer surface of the bent portion 2c are substantially at the same position.

  A base 6 is attached to the pair of end portions 2d, 2d of the glass bulb 2 so as to straddle both end portions 2d, 2d. The base 6 includes a power feeding portion 6 a composed of four pins that are electrically connected to the pair of electrodes 5 and 5. The fluorescent lamp 1 is configured such that three bent portions 2 c are formed at diagonal positions of a substantially square shape formed by the straight tube portion 2 b of the glass bulb 2, and a base 6 is provided at the remaining one location. The two end portions 2d and 2d of the glass bulb 2 are angled with respect to each other so that the angle formed by the tube axes of the straight tube portions 2b and 2b constituting the end portions 2d and 2d is 90 °. Facing each other.

  The power feeding part 6a comprising the four pins of the base 6 is an electrical connection means for connecting to a power feeding means such as a socket. This electrical connection means is provided at a position away from both end portions 2d and 2d of the valve. May be. The base 6 may be configured to exhibit a function as a holding means by mechanical connection with a power supply means such as a socket.

  The bulb 2 may be configured such that the coldest portion is formed in at least one bent portion when the fluorescent lamp is turned on. The coldest part is formed at the lowest temperature part of the bulb when the fluorescent lamp 1 is lit, and the bent part may be formed so that the temperature does not easily rise during lighting. For example, there are a structure that forms a space away from the discharge path, a structure that has a larger surface area than other parts, and has an excellent heat dissipation effect.

  Further, it is possible to form the coldest part on the valve end 2d by separating the arrangement positions of the electrodes 5 and 5 from the valve end 2d by a predetermined length or more. For example, by setting at least one electrode height (the length from the bulb end to the electrode placement position) to be 30 mm or more, the coldest portion can be formed at a desired location on the bulb end. If it is possible to control the coldest part to the desired temperature, it is possible to ensure the optimum mercury vapor pressure without using an amalgam for mercury vapor pressure control even if the ambient temperature is high, and lamp efficiency Can be further improved.

  Next, the manufacturing method of the glass bulb | ball 2 used for the fluorescent lamp 1 of this embodiment is demonstrated.

  In this manufacturing method, the bent portion is formed by thermoforming the straight tubular bulb. However, the bent portion formation scheduled portion is not a straight tubular bulb in which the phosphor layer is uniformly formed on the inner surface of the conventionally used bulb. Is manufactured using a straight tube bulb in which a phosphor layer having a smaller amount of phosphor adhering than the straight tube portion is formed, and the bent formation portion is heated by using this to be bent. The fluorescent lamp of the present invention is provided.

  First, FIG. 2 will be described with respect to the production of a straight tubular bulb having a different amount of phosphor layer deposited, and the step of bending the produced straight tubular bulb to form the fluorescent lamp of the present invention will be described with reference to FIG.

  First, a straight tubular glass bulb is prepared as in the prior art, and alumina is applied to the inside of the bulb and dried to form a protective film 3 as shown in FIG. A first phosphor layer is formed on the protective film 3 as shown in FIG.

  The production of the conventional fluorescent lamp is finished at this stage, and a protective film and a phosphor layer are formed with a uniform thickness on the inner surface of the straight tubular bulb in order to stabilize the production, cost, and luminous efficiency. It had been.

  In the manufacturing method of the fluorescent lamp of the present invention, in order to make the thickness of the phosphor layer formed on the inner surface of the straight tube bulb (the amount of phosphor attached) different between the straight tube portion and the bent formation scheduled portion, In addition, the bent portion 2e of the straight tubular bulb on which the protective film and the phosphor layer are formed is heated to 250 to 450 ° C., whereby the binder of the phosphor layer is incinerated and removed, and further, the binder is removed. Is removed from the protective film 3 by blowing about 10 atm of compressed air from one end of the bulb, and only the protective film is formed in the bent portion formation planned portion 2e as shown in FIG. In the state where the phosphor layer is formed on the protective film 3 in the straight pipe portion 2b, a second phosphor layer is formed on the inner surface of the bulb again by applying the phosphor layer to the inner surface of the bulb 2b. As shown in (d), the bent portion formation scheduled portion 2e Only the second phosphor layer, the straight tube portion 2b and forms a phosphor layer 4 which is the first phosphor layer and second phosphor layer are laminated.

  In addition, in order to remove a part of the phosphor layer, in addition, a brush is inserted inside the tube, the phosphor film of the portion where the bent portion is to be formed is rubbed off, washed, and the phosphor solvent. Forming a phosphor layer using a mixed solution of polyvinyl alcohol and dichromic acid as follows, and then irradiating only the straight tube part with ultraviolet rays, only the ultraviolet irradiation part is fixed, so that no bending is applied to the ultraviolet rays. A method of removing the phosphor layer of the planned portion by rinsing with water can be exemplified. Regardless of which method is used, the phosphor layer in the bent formation scheduled portion is smaller than the straight tube portion by the amount of the first phosphor layer attached, that is, thinner by the thickness of the first phosphor layer. Will be formed.

  Using the straight tubular valve 2a thus obtained, the exhaust pipes 2f are provided at both ends 2d and 2d, and the electrodes 5 and 5 are connected to the inside of the valve 2a via a flare stem (not shown) for introducing a pair of lead wires. Attach to.

  The straight tubular valve 2a has a total length of 1200 mm, and has three bent portion formation scheduled portions 2e as shown in FIG.

  First, as shown in FIG. 3A, the bent portion formation scheduled portion 2e is heated and softened by the gas burner B, and the angle formed by the straight tube portions 2b is about 90 ° as shown in FIG. 3B. Then, the first bent portion 2c is formed into a predetermined shape by molding or the like. After that, the bent portion formation scheduled portion 2e adjacent to the first bent portion 2c is heat-softened, bent, and molded by the gas burner B to form the second bent portion 2c as shown in FIG. To do. Finally, the bent portion formation scheduled portion 2e adjacent to the second bent portion 2c is heat-softened, bent, and molded by the gas burner B to form the third bent portion 2c as shown in FIG. 3 (d). Then, air is exhausted from the exhaust pipe 2f, and mercury is enclosed to complete the glass bulb 2.

  The bent portion 2c is formed by bending, but it is not necessary to excessively heat the portion other than the bent portion forming scheduled portion 2e of the straight tubular bulb 2a. Therefore, the phosphor layer 4 is applied before forming the bent portion 2c. However, the phosphor is less likely to be thermally deteriorated, and the luminous flux maintenance factor is greatly improved.

  The fluorescent lamp 1 can have the following dimensions. The equivalent of a conventional 30 W type annular fluorescent lamp is formed such that the total length of the glass bulb 2 is 225 mm, the maximum inner width is 192 mm, the outer diameter of the tube is 16 mm, and the thickness of the glass bulb 2 is 1.0 mm. The fluorescent lamp is lit at a rated lamp power of 20 W and a lamp power of 27 W with high output characteristics. The conventional 32 W type annular fluorescent lamp has a glass bulb 2 with an overall length of 299 mm, an inner maximum width of 267 mm, a tube outer diameter of 16 mm, and a glass bulb 2 having a thickness of 1.0 mm. The fluorescent lamp is lit with a rated lamp power of 27 W and a lamp power of 38 W with high output characteristics. The equivalent of a conventional 40 W type annular fluorescent lamp is formed such that the total length of the glass bulb 2 is 373 mm, the maximum inner width is 341 mm, the outer diameter of the tube is 16 mm, and the thickness of the glass bulb 2 is 1.0 mm. The fluorescent lamp is lit at a rated lamp power of 34 W and a lamp power of 48 W with high output characteristics.

  The film thickness of the protective film 3 formed on the inner surface of the annular bulb 2 of the fluorescent lamp 1 is 0.5 μm or more, and the phosphor layer 4 is formed on the protective film 3 and is made of mercury sealed in the bulb. The amount is preferably 0.15 mg / W or less.

  Mercury enclosed in the bulb 2 is consumed by reacting with phosphor fine particles and alkali components deposited from the bulb during the operation of the fluorescent lamp to change into a mercury compound or being driven into the bulb. The amount used as is gradually reduced. Further, the mercury consumption has a relationship that is almost proportional to the lamp power. Therefore, a large amount of mercury is enclosed in the bulb 2 in consideration of the amount consumed in the bulb 2 until the end of its life according to the lamp power. However, it is desirable to reduce the amount of enclosed mercury as much as possible in consideration of the influence on the surrounding environment during the lamp manufacturing process and lamp disposal.

  If the thickness of the protective film 3 is 0.5 μm or more, it can be expected to suppress the reaction between alkali components in the bulb and mercury and the phenomenon that mercury is injected into the bulb, and the amount of mercury consumed during lamp operation. Can be reduced. In the fluorescent lamp 1 of the present embodiment, since the straight tube portion 2b is not substantially stretched, even if the thickness of the protective film 3 formed on the straight tube bulb 2a is increased to 0.5 μm or more, the bent portion forming step As a result, there is no risk of cracks or the like occurring in the protective film of the straight pipe portion, and the function of the protective film 3 can be sufficiently exhibited.

  Further, when the thickness of the protective film 3 is 0.5 μm or more, the mercury consumption is greatly reduced in combination with the function of the protective film 3 and the fact that the straight pipe portion 2b is not directly heated to the extent of softening. As a result, it was confirmed that even if the amount of enclosed mercury per lamp power was set to 0.15 mg / W or less, it was possible to continue lighting without exhaustion of mercury until the lamp rated lifetime was reached. As described above, by setting the thickness of the protective film 3 to 0.5 μm or more, it is possible to satisfy the rated life even if the amount of enclosed mercury per lamp power is 0.15 mg / W or less.

Further, by using fine particles having a high ultraviolet reflectance for the protective film 3, it is possible to reduce the phosphor coating amount to about 3.0 to 4.6 mg / cm ² without reducing the light emission amount. This is an effect obtained by forming the protective film 3 mainly composed of metal oxide or metal phosphate fine particles having a high ultraviolet light reflection effect with a wavelength of 254 nm and a high visible light transmittance. As such fine particles, for example, those having a reflectivity of 60% or more with respect to that of barium sulfate and an reflectivity of 60% or less with respect to that of barium sulfate are preferably 60% or less with respect to those of barium sulfate. Specifically, α-alumina (α-Al ₂ O ₃ ), calcium phosphate (Ca ₂ P ₂ O ₇ ), strontium phosphate (Sr ₂ P ₂ O ₇ ), and the like are suitable, but ultraviolet light having a wavelength of 254 nm is reflected. The present invention is not limited to this as long as the effect is high and the visible light transmittance is high. Further, when the average particle diameter of the fine particles is 1.0 to 10 μm, the surface area of the fine particles is reduced, and the exhaust efficiency is improved by lowering the adsorption level of impure gas such as water and hydrogen gas. .

The metal oxide fine particles constituting the protective film 3 have a specific surface area of 80 m ² / g or more, and the coating amount of the fine particles per unit area in the bulb is 0.01 to 0.8 mg / cm ² . This is preferable for preventing reaction between phosphor particles in the phosphor layer and alkali components in the bulb and coloring of the bulb, and the effect is particularly remarkable when the lamp is lit at a tube wall load of 0.05 W / cm ² or more. It is.

  The tube wall load means the lamp input power per inner surface area of the bulb 2. The greater the value of the tube wall load, the greater the amount of heat generated, and the higher the temperature at the time of lighting, the more the phosphor layer 4 reacts with the alkaline component in the bulb and the phosphor layer 4 tends to deteriorate with time. Also, the greater the value of the tube wall load, the greater the amount of short-wavelength UV radiation. The alkali component of the bulb precipitates and reacts with mercury, and the bulb is more likely to be colored due to mercury being injected into the bulb. Therefore, the visible light transmittance tends to be remarkably lowered. Here, the “inner surface area of the bulb” refers to the inner surface area of the bulb in the region where the discharge path is formed, not the total inner surface area of the bulb.

In the fluorescent lamp on which this protective film is formed, the straight tube portion is not substantially stretched. Therefore, even if the coating amount of the protective film 3 formed on the straight tubular bulb 2a is increased, the straight tube portion is not directly stretched. There is no possibility that cracks or the like are generated in the protective film 3 of the tube portion 2b, and the function of the protective film 3 can be sufficiently exhibited. In addition, since the specific surface area is 80 m ² / g or more, the protective film 3 has a very dense structure, and alkali components, mercury, and the like deposited from the bulb 2 are blocked by the protective film. The coloring of 2 can be effectively suppressed.

  Annular fluorescent lamps are formed in an annular shape by forming a phosphor layer on a straight tube bulb, then heating and softening the entire bulb and bending it to an annular drum. The entire bulb is slightly stretched, and there is a possibility that the phosphor layer previously formed may be cracked or peeled off. For this reason, it is difficult for the annular fluorescent lamp to increase the thickness of the phosphor layer to a predetermined value or more. This is one of the factors that make it difficult to improve the light emission amount of the annular fluorescent lamp.

  On the other hand, since the straight tube portion 2b is not substantially stretched in the fluorescent lamp 1 of this embodiment, even if the thickness of the phosphor layer 4 formed on the straight tube bulb 2a is increased, the bent portion There is no possibility that the phosphor layer 4 is cracked or peeled off by the forming process.

In the fluorescent lamp 1 of the present embodiment, the straight tube portion 2b has a tube outer diameter of 12 to 20 mm, and the amount of ultraviolet rays applied to the tube inner surface tends to increase. In 5.5, it is set to 5.5-8.0 mg / cm < ² >. This is because if the coating amount is less than 5.5 mg / cm ² , the effect of improving the light emission amount is small and the amount of ultraviolet light transmitted may increase. The effect of improving the light emission amount is significant when the coating amount of the phosphor fine particles is 6.5 to 7.5 mg / cm ² . Further, if the coating amount of the phosphor fine particles exceeds 8.0 mg / cm ² , the effect of improving the light emission amount due to the increase in the thickness of the phosphor layer 4 does not appear remarkably.

As described above, in the present embodiment, since the coating amount of the phosphor fine particles constituting the phosphor layer 4 is 6.0 to 7.0 mg / cm ² , the phosphor layer 4 of the straight tube portion 2b is cracked or The amount of light emission can be improved without causing peeling.

Moreover, the application amount of the phosphor fine particles is set to 3.5 to 5.5 mg / cm ² at the bent portion. If the coating amount is less than 3.5 mg / cm ² , a sufficient amount of light emission cannot be obtained, so that the light emission efficiency is lowered and the difference in light emission amount from the straight tube portion is increased. Since only the straight pipe portion appears to emit light, there is a problem in appearance. On the other hand, when the coating amount exceeds 5.5 mg / cm ² , cracks and peeling occur in the phosphor layer when the bent portion is formed.

Next, the operation of this embodiment will be described. The fluorescent lamp 1 receives high frequency power from the base 6 and is turned on by low pressure mercury vapor discharge in the bulb 2. The fluorescent lamp 1 is lit so that the lamp input power is 20 W or more, the lamp current is 200 mA or more, the tube wall load is 0.05 W / cm ² or more, and the lamp efficiency is 501 m / W or more. The lamp current density, which is the lamp current per cross-sectional area of the straight pipe portion 2b, is 75 mA / cm ² or more. In this embodiment, the lamp input power is 50 W, the lamp current is 380 mA, and the lamp efficiency is 901 m / W.

  When the fluorescent lamp 1 is turned on, the temperature of the bulb 2 rises to about 80 ° C. However, since the bismuth (Bi) -tin (Sn) -lead (Pb) amalgam is accommodated in the narrow tube 2f, The vapor pressure inside the bulb is controlled to an appropriate value by the mercury vapor pressure characteristic of amalgam, and it becomes possible to light with high lamp efficiency.

  In this embodiment, the glass bulb 2 is formed by locally bending one straight tubular bulb 2a. However, the glass bulb 2 is formed by two bulbs bent in an L shape. The glass bulb 2 may be configured by connecting the ends of the glass bulb 2 to form one bent portion.

By the way, the glass bulb 2 can be used with substantially no lead component, a sodium oxide content of 1.0 mass% or less, and a softening temperature of 720 ° C. or less. Here, “substantially free of lead component” means that it may be contained as long as it is an impurity, and preferably 0.1% by mass or less. Of course, the most preferable glass is one containing no lead component. The content of sodium oxide of 0.1% by mass or less includes the case where sodium oxide is not contained in the glass. The reason why the content of sodium oxide is defined as 0.1% by mass or less is that when the above value is exceeded, the amount of light emitted from the fluorescent lamp 1 is affected by the sodium component deposited on the inner surface of the glass bulb 2. As a glass having a composition containing substantially no lead, a sodium oxide content of 1.0% by mass or less, and a softening temperature of 720 ° C. or less, the contents of K ₂ O and Li ₂ O and CaO, MgO, It can be obtained by adjusting the content of BaO and SrO. Here, the softening temperature is a temperature at which the glass has a viscosity η = 107.65 dPa · s.

  When sodium oxide exceeds 0.1% by mass on the glass bulb 2, a large amount of sodium is deposited on the inner surface of the glass bulb 2 as an alkaline component during lighting. When this sodium is deposited on the inner surface of the glass bulb 2, the sodium and mercury vapor sealed in the glass bulb 2 react to color the glass bulb 2 to reduce the visible light transmittance, or sodium is a phosphor. The phosphor material reacts with the phosphor material of the layer 4 to cause a problem that the output of visible light is reduced. In particular, since the conventional soda lime glass contains 15 to 17% by mass of sodium oxide, the output of visible light is significantly reduced.

  Therefore, when a phosphor is applied to a straight tubular bulb 2a made of glass having a sodium oxide content of 0.1% by mass or less and a softening temperature of 720 ° C. or less, for example, 692 ° C., and then a bent portion is formed, The amount of sodium deposited on the substrate is extremely small, and the decrease in the amount of visible light emitted by the sodium reaction is suppressed. Further, since the softening temperature is 720 ° C. or lower, the heating temperature at the time of forming the bent portion is kept low, the thermal deterioration of the surrounding phosphor is reduced, and the light emission amount is improved.

  FIG. 4 is a front view showing a fluorescent lamp according to the second embodiment of the present invention. This embodiment is the same as the first embodiment except that the base 6 is located at the approximate center of one side of the substantially square shape.

  FIG. 5 is a front view showing a fluorescent lamp according to the third embodiment of the present invention. This embodiment is an optimization of the fluorescent lamp of the second embodiment shown in FIG. 4 and is the same as the second embodiment except for the configuration of the bent portion 2 c and the base 6.

  The length of one side of the glass bulb 2 is 300 mm, the lamp current of the fluorescent lamp 1 is 300 mA, and the lamp power is about 40 W. By adjusting the inverter device, the lamp current can be 380 mA, the lamp power can be about 50 W, and high output lighting can be performed.

  When the lamp current of the fluorescent lamp 1 is 300 mA, the lamp power is about 30 W when the length of one side of the glass bulb 2 is 225 mm, the lamp power is about 50 W when the length is 375 mm, and the lamp power is about 450 mm. It can be lit at about 60W. Further, when the length of one side is 500 mm and the lamp current is 380 mA, it is possible to obtain a high-illuminance and high-efficiency fluorescent lamp that is optimal for use in a lighting device for a grid ceiling installed in an office or the like. .

  The base 6 is spanned between both end portions 2d and 2d disposed so as to face each other so that the tube axes thereof are substantially on the same line, and is located at the approximate center of one side of the substantially square valve 2. Yes. The base 6 is formed of a cylindrical resin hollow body, and four base pins 6 a serving as power feeding portions are provided on the surface of the base 6. The cap pin 6a is provided so as to protrude about 45 ° with respect to the plane formed by the bulb 2 and to face the center side of the bulb 2.

  The base 6 is attached to the valve end portions 2d and 2d together with the rotation restricting means so as to rotate about ± 45 ° about the tube axis of the valve end portions 2d and 2d. When the rotation restricting means exceeds a certain rotation angle, the inner surface of the base 6 and the valve end 2d, so that the base 6 side and the valve end 2d, 2d side interfere with each other and cannot rotate. This can be realized by providing protrusions at predetermined positions with respect to the outer surface of 2d, but the rotation restricting means is not limited to this. When the base 6 is configured to be rotatable beyond a predetermined angle, the outer lead wire connecting the base pin 6a and the electrode 5 is deformed by tension, and the outer lead wires come into contact with each other inside the base 6 and are short-circuited. Therefore, it is necessary to restrict the rotation to be less than a predetermined rotation angle.

  6 and 7 show the length L in the axial direction of the bulb where the amount of the phosphor deposited on the bent portion formation planned portion is small, and the inner surface of the bent portion obtained by bending the bent portion formation planned portion. It is the figure which showed the relationship with the curvature radius R. 6 corresponds to the fluorescent lamp of FIG. 4 and FIG. 7 corresponds to the fluorescent lamp of FIG. 5, and the radii of curvature of the bent portions are different.

  As shown in FIG. 6A, the bent portion formation planned portion 2e of the straight tubular bulb 2 before bending is formed with a phosphor layer with a small amount of phosphor attached, which is represented by diagonal lines. Let L be the length of this phosphor layer in the axial direction of the bulb.

Although the bent portion 2c which is represented by FIG. 6 (b) is formed by bending it, this time, the center of the radius of curvature R ₂ of the radius of curvature R ₁ and the outer surface of the inner surface of the bent portion 2c is The inner surface of the bent portion 2c means a surface facing the central portion of a virtual annular plane formed by the annular valve, and the outer surface of the bent portion 2c is the bent portion. Means a surface located on the opposite side from the inner surface by 180 ° around the tube axis (a surface facing in a direction radiating in parallel along the same plane from the center of the annular plane formed by the annular valve).

The curvature radius R of the inner side surface is defined by a curve formed at a position where the inner side surface and the virtual annular plane formed by the annular valve 2 are orthogonal to each other. For simplicity, the radius R of the virtual annular plane formed by the annular valve 2 is defined. Each can be defined by the radius of curvature of the contour line formed at the bent portion when the annular valve is observed from the orthogonal direction. The optimum range of the radius of curvature _{R 1} is 13～30Mm, preferably 15 to 25 mm, the radius of curvature _{R 1} in the present embodiment is 20 mm.

  The relationship between R and L defined in this way is preferably in the range of 0.5 <L / R <5.0. In FIG. 6, a phosphor layer with a small amount of phosphor attached is a straight tube. The region up to the portion 2b is formed, and the phosphor layer can be sufficiently prevented from being cracked or peeled off at the bent portion 2c. On the other hand, when the phosphor layer with a small amount of phosphor attached is formed only in the area of the bent portion before the straight tube portion, the luminous efficiency is high because the straight tube portion has a large amount of phosphor adhered. Is very good. Since L is short, if the L / R is 0.5 or less, cracking or peeling of the phosphor layer at the bent portion cannot be sufficiently suppressed, and since L is long, L / R is 5 If it is 0.0 or more, cracking and peeling of the phosphor layer at the bent portion can be suppressed, but the luminous efficiency of the fluorescent lamp is increased because there are many areas where the amount of phosphor adhering is small in the straight tube portion. It will decline.

  FIG. 7 shows a case where a bent portion having a larger radius of curvature than that of FIG. 6 is provided.

The radius of curvature R ₁ is larger, the range of the valve to be bent as the bent portion becomes longer, the length of the fluorescent phosphor layer deposition amount is small, which hatched with it L also requires a certain length Become. However, even when the radius of curvature changes in this way, as long as the relationship of 0.5 <L / R ₁ <5.0 is satisfied, the crack and peeling at the bent portion are suppressed, and the light emission amount at the straight tube portion. It is possible to achieve both of ensuring.

  Although the above description has been made on a substantially rectangular annular fluorescent lamp, the present invention is a fluorescent lamp having a straight tube portion and a bent portion, for example, a fluorescent lamp formed into an L shape, a U shape, etc. by bending a straight tube bulb. If so, it can be applied.

It is a top view of the fluorescent lamp of the 1st Embodiment of this invention. It is sectional drawing of the valve | bulb explaining preparation of a straight tubular valve | bulb. It is the schematic explaining the manufacturing process of the fluorescent lamp of FIG. It is a top view which shows the fluorescent lamp which is the 2nd Embodiment of this invention. It is a top view which shows the fluorescent lamp which is the 3rd Embodiment of this invention. It is the figure which showed the bending part before and behind the bending process of the fluorescent lamp of FIG. It is the figure which showed the bending part before and behind the bending process of the fluorescent lamp of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fluorescent lamp, 2 ... Glass bulb, 2a ... Straight tube bulb, 2b ... Straight pipe part, 2c ... Bending part, 2d ... End part, 2e ... Bending formation part, 3 ... Protective film, 4 ... Phosphor layer, 5 ... Electrode, 6 ... Base

Claims (7)

By heating and bending the portion where the bent portion of the straight tubular valve is to be bent, the center of the radius of curvature of the inner surface and the outer surface is substantially the same position and the tube diameter is substantially the same as the tube diameter of the adjacent straight tube portion. A bulb in which electrodes are sealed at both ends so that one discharge path is formed through the straight tube portion and the bent portion, and a discharge medium containing mercury is enclosed;
A phosphor layer formed on the inner surface of the bulb and having a smaller amount of phosphor adhering to the bent portion than the straight tube portion;
Bases provided at both ends of the valve;
A fluorescent lamp characterized by comprising: The adhesion amount x per unit area of the phosphor in the bent portion is in the range of 3.5 to 5.5 mg / cm ² , and the adhesion amount y per unit area of the phosphor in the straight tube portion is 5.5 to 5.5. The fluorescent lamp according to claim 1, wherein the fluorescent lamp has a range of 8.0 mg / cm ² .   The ratio between the amount x of phosphor adhering per unit area and the amount y of phosphor adhering per unit area satisfies a relationship of 0.40 <x / y <0.75. 2. The fluorescent lamp according to 2.   The length L in the axial direction of the bulb where the amount of the phosphor deposited on the bent portion formation planned portion is small, and the curvature radius R of the inner surface of the bent portion after bending the bent portion formation planned portion 4. The fluorescent lamp according to claim 1, wherein the ratio satisfies a relationship of 0.5 <L / R <5.0.   The fluorescent lamp according to claim 1, wherein the bulb is annular. A first phosphor layer forming step of forming a first phosphor layer having a uniform thickness on the inner surface of the straight tubular bulb;
A phosphor layer removing step of removing the phosphor layer in the bent portion formation scheduled portion of the straight tubular bulb in the formed first phosphor layer;
A second phosphor layer forming step of forming a second phosphor layer having a uniform thickness on the inner surface of the straight tubular bulb;
A bent portion forming step of forming a bent portion by heating and bending the bent portion forming scheduled portion having a small amount of phosphor adhering among the phosphor layers having different thicknesses formed by these steps;
A method for manufacturing a fluorescent lamp, comprising:   In the phosphor layer removing step, the phosphor layer in the bent portion formation scheduled portion is heated from the outside of the bulb to burn and remove the binder in the phosphor layer, and then the bent portion formation planned portion is compressed with compressed air. The method of manufacturing a fluorescent lamp according to claim 6, wherein the fluorescent lamp is removed by spraying.

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