JPH01186747A - Fluorescent lamp - Google Patents

Abstract

PURPOSE:To make it possible to suppress the falling off of the luminous flux during the operation of a lamp and to enlarge the voltage drop so as to obtain higher luminous output by forming the inner periphery of the 2nd. bended portion of a double U-shaped fluorescent lamp to a curve containing a circular arc of negative curvature to that of the outer periphery. CONSTITUTION:Both end portions of an U-shaped glass tube 1 with a 1st. bended portion are bended further along the direction perpendicular to the plane containing the U-shaped glass tube to form a 2nd. bended portion, where the 2nd. bended portion is bended along a roller the cross section of which has a recessed portion in inner side so as that the inner periphery of the 2nd. bended portion is constructed with a curve containing a circular arc of negative curvature R. Therefore the expansion to the outside direction can be suppressed significantly and the discoloration of the phosphor 2 in this portion can be reduced. Thereby the consistency of the luminous flux during the life time of the lamp can be improved and the voltage drop can be enlarged to obtain higher luminous output.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a double U-shaped fluorescent lamp.

BACKGROUND OF THE INVENTION 1. Conventional Technology Compact fluorescent lamp devices with high efficiency and long life, which are integrated with ballasts and lighting tubes, have become widely used as a new product field of light sources for lighting. Compact design fluorescent lamps usually employ a folded discharge path system with three bends. That is, a phosphor film is formed on the inner surface of a glass tube having a first bent part that has been formed into a U-shape in advance, and electrodes are sealed at both ends of the phosphor film, and then the central part of the glass tube is heated to a temperature higher than its softening temperature. Then, it is bent 180° along a roller with a radius of curvature d/2 to form a second bent part, and molding air is blown into the inside from the other end to expand it outward to obtain a desired shape. The double U-shaped fluorescent lamp made by this method has a large light output despite its extremely compact size (and is also economical because it is easy to manufacture, and is required for the arc tube of compact fluorescent lamp devices. It has many characteristics that make it unique.

Problems to be Solved by the Invention However, in this method, during the manufacturing process, the second bending portion expands outward from the roller by the forming air, so the glass is significantly stretched at that portion and the wall thickness is reduced to the original thickness. It is often experienced that the thickness becomes less than 1/2. As a result, the mechanical strength of the arc tube becomes weak (and at the same time, the thickness of the phosphor film in this part becomes thinner, so the phosphor deteriorates due to ultraviolet rays and only the second bent part becomes partially blackened, causing the lamp to This type of compact fluorescent lamp is usually operated with high output specifications, but in the case of compact fluorescent lamps, it is usually used in a sealed high-temperature atmosphere. This tendency is further exacerbated by the fact that the lamp is lit inside the room.Particularly in countries like Japan where the power supply voltage is 100V, so-called low-power countries, the lamp voltage must be kept below 56V, so the diameter of the glass tube is large ( However, the discharge path cannot be too long in order to ensure starting performance.

As a result, the proportion of the second bent part in the entire discharge path is thicker than that of the high-voltage version with a power supply voltage of 220V. Met.

An object of the present invention is to suppress the decrease in the thickness of the phosphor film in the second bending part as much as possible to suppress the decrease in luminous flux during the movement of the lamp, and to
The object of the present invention is to provide a fluorescent lamp that can obtain higher light output by increasing the voltage drop while keeping the physical dimensions of the glass tube constant.

Means for Solving the Problems In the fluorescent lamp of the present invention, a U-shaped glass tube having a first bent portion is further bent into a U-shape at both ends thereof along a direction perpendicular to a plane containing the U-shaped glass tube. The glass tube includes a glass tube having a second bent portion, and the inner periphery of the second bent portion is formed of a curved line including an arc having a negative curvature with respect to the outer periphery.

action This configuration provides the following two effects.

In general, if a glass tube with outer diameter a is attached to a roller with diameter d, for example, a = 15.5 + w *, d = 20 m, this value is 20151 = 0.4 times, or the calculated value is 40 m.
% wall thickness. The phosphor film formed on the inner surface of the glass tube also becomes thinner at the same rate.

Usually, the film thickness of the phosphor is considered to be 4 to 5 mg/c-. However, since the portion bent by the above method has a film thickness of about 2 cm/C-, it deteriorates and discolors due to ultraviolet irradiation during its life. In order to suppress outward elongation, if the glass is compressed at the contact surface with the roller, wrinkles will occur inside the bent portion, resulting in partial distortion and increasing the risk of cracks in the glass.

The double U-shaped fluorescent lamp of the present invention is bent along a roller with a cross-sectional shape having a recess on the inside, and its inner periphery is constituted by a curved line including an arc of negative curvature. When bent into a shape, wrinkles that are generated due to compression at the roller contact surface are absorbed into the recesses without being localized, so there are no cracks caused by distortion. Therefore, outward expansion is significantly suppressed, deterioration and discoloration of the phosphor in this portion is also reduced, and the luminous flux maintenance rate during the lamp life is also improved.

Another effect of this shape is an increase in light output due to the higher voltage drop.

In FIG. 3, in a conventional double U-shaped fluorescent lamp having a folded discharge path formed along an arcuate roller with a diameter d, the arc is not formed on the tube axis C, but passes near the folded part ( It is formed at the position of the mouth). This fact has great significance when the highest possible light output is required while being limited by the physical dimensions of a compact fluorescent lamp device (i.e., the voltage drop across the lamp is The actual position (b) is lower than the assumed position (a).On the other hand, as shown in FIG. Therefore, the arc is on the tube axis (A)
It is formed at the position of Therefore, the voltage drop increases and the optical output becomes higher than in the past.

Embodiment 1 Below, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a main part of a fluorescent lamp according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a U-shaped glass tube having a first bent portion, and a glass tube having a second bent portion, which is further bent into a U-shape at both ends of the U-shaped glass tube along a direction perpendicular to a plane containing the U-shaped glass tube. 2 is the phosphor film formed on the inner surface of the tube, a is the outer diameter of the glass tube, R is the wall thickness of the glass tube, t2 is the glass wall thickness of the second bent portion, d is the width of the second bent portion, R indicate the negative radius of curvature of the concave portion of the second bending portion.

Glass tube outer diameter a is 15.5w+, wall thickness is 1. is 1.0 cm, the width d of the second bent part is 20 cm, and the radius of curvature of the concave part is R.
Electrodes (not shown) were sealed at both ends of the glass tube with a distance of 8 m, and a double U-shaped lamp was formed with a distance of 280 m5 between the electrodes. As the phosphor, a mixed phosphor of europium-activated yttrium dioxide and terbium-activated cerium/magnesium aluminate was used. The glass wall thickness t2, which indicates the elongation rate of the bent portion, was 0.85 m+, which was significantly improved compared to the conventional bent shape (the inner peripheral shape is shown by the chain line). In the normal fluorescent lamp exhaust process, this is heated to 400 Pa of argon and 6
A low-pressure mercury discharge lamp was completed by enclosing nur mercury and a bismuth-indium alloy of 200 mm to suppress an excessive rise in mercury vapor pressure in high-temperature conditions.

This lamp is installed at an ambient temperature of 25℃, a power supply voltage of 100V, and a
Standard ballast for W fluorescent lamps (impedance 244Ω)
Table 1 shows a comparison of the characteristics when lit in the circuit with a conventional product (however, the dimensions are the same).

As is clear from Table 1, although the dimensions of the double U-shaped lamp after molding are the same as those of the conventional product, the product of the present invention has an increased light output due to an increase in lamp voltage compared to the conventional product. I know that there is.

Next, we fabricated a compact fluorescent lamp device with a rated current of 300 mA by incorporating both lamps into a sealed outer bulb with a ballast, lighting tube, and light bulb base as a luminous tube. Table 2 shows the results of measuring the main line.

Table 2 As is clear from Table 2, the product of the present invention has an improved luminous flux maintenance factor compared to the conventional product. Furthermore, even after the product of the present invention had been lit for 6,000 hours, which is the average lifespan, the coloring caused by deterioration of the phosphor in the second bent portion, which was observed in the conventional product, was extremely slight.

As described in detail, the fluorescent lamp of the present invention includes a U-shaped glass tube having a first bent portion, and the both ends of the U-shaped glass tube are further shaped into a U-shape along a direction perpendicular to a plane containing the U-shaped glass tube. Double U consisting of a glass tube with a bent second bent part
In the shaped fluorescent lamp, the inner periphery of the second bent portion consists of a curved line including an arc having a negative curvature with respect to the outer periphery.
The elongation rate of the outer layer of the second bent portion is significantly suppressed. Therefore, when the fluorescent lamp of the present invention is integrated with a ballast and lighting tube into a light bulb base and a sealed outer bulb to form a compact fluorescent lamp device, the phosphor in the second bent portion deteriorates and discolors throughout the life of the lamp. Since the light is suppressed to a very low level, the luminous flux maintenance rate is maintained at a high level. At the same time, the effective length of the arc generated between the two electrodes in the lamp increases, so the lamp voltage increases, and there is also the advantage that an increase in light output can be obtained without increasing the size of the lamp. The effect is extremely large.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the main parts of a fluorescent lamp which is an embodiment of the present invention, Fig. 2 is an explanatory diagram showing the position of an arc generated in the tube of the same fluorescent lamp, and Fig. 3 is an illustration of the inside of the tube of a conventional fluorescent lamp. FIG. 1... Glass tube, 2... Fluorescent film.

Claims (1)

[Claims] A U-shaped glass tube having a first bent portion, with both ends of the U-shaped glass tube having the first bent portion
A glass tube having a second bent part further bent into a U shape along a direction perpendicular to a plane containing the shaped glass tube, the inner periphery of the second bent part having a negative curvature with respect to the outer periphery. A fluorescent lamp characterized by being composed of a curved line including an arc.