JPH09320525A - Ring fluorescent lamp - Google Patents

Abstract

(57) Abstract: To improve the light output and the luminous flux maintenance factor of a ring-shaped fluorescent lamp. SOLUTION: The tube diameter near the central portion of the discharge tube is made thicker than other portions.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an annular fluorescent lamp.

[0002]

2. Description of the Related Art The mercury atom density at which the generation efficiency of the resonance line of mercury that illuminates the fluorescent material of a fluorescent lamp is maximized corresponds to a temperature of about 40.degree. C., although the structure size of the lamp is slightly different. Is also described in, for example, the Writing Handbook published by Ohmsha, Inc., Illuminating Society of Japan. On the other hand, compact fluorescent lamps, ring fluorescent lamps, etc. are miniaturized and have a high load structure, so the temperature of the lamp often exceeds the above optimum temperature and becomes high. There is also an example of using amalgam to control the. Further, an example in which the tube diameter in the vicinity of the lamp tube end electrode is made large in order to control the mercury vapor pressure is described in, for example, Japanese Patent Publication No. 4-63507.

It is also well known that the thicker the tube diameter, the lower the potential gradient of the discharge and the decrease in the tube wall load coupled with the increase in the surface area.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to improve the efficiency of a ring-shaped fluorescent lamp with a simple structure.

[0005]

In order to achieve the above object, in the ring-shaped fluorescent lamp of the present invention, the tube diameter at the central portion of the lamp is increased. With the above configuration, the mercury vapor pressure is properly controlled by preventing an excessive rise in the temperature of the thick tube portion,
The efficiency of the lamp can be increased.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION

<Embodiment 1> FIG. 1 is a view showing an embodiment (a base portion is not shown) of an annular fluorescent lamp of the present invention. The discharge tube 1 has a ring shape with an outer diameter of 226 mm and an inner diameter of 188 mm, and the tube diameter is 19 mm at the portion a and 25 mm at the portion b. An alumina protective film and a phosphor are applied inside the discharge tube 1 made of soft glass, and a predetermined amount of mercury and a rare gas are enclosed. Filament electrodes 2a and 2b coated with electron emitting substances are mounted on both ends of the discharge tube 1 and are connected to a base (not shown).

When this lamp is turned on at 28 watts input, when the outside air temperature is 25 ° C., the temperatures of parts a, b, and electrodes are 48 ° C., 45 ° C., and 47 ° C., respectively, and the vapor pressure of mercury is the coldest. Controlled in part b. For comparison, when a lamp having the tube diameter of the b portion made equal to that of the a portion was prototyped and compared with this lamp, the luminous flux ratio at the same input was higher by about 1%.

<Embodiment 2> Similarly, as another embodiment of the present invention, the outer diameter and the inner diameter of the discharge tube 1 are set to 2 respectively.
26 mm and 194 mm, and the pipe diameters of part a and part b respectively
16mm, 22mm, 28 Watt input, when lit,
When the outside air temperature was 25 ° C, the temperatures of the parts a, b, and the electrodes were 50 ° C, 47 ° C, and 49 ° C, respectively, and the vapor pressure of mercury was controlled in the coldest part b. For comparison, as in Example 1, a lamp was manufactured in which the tube diameter of the b portion was made equal to that of the a portion, and the result was compared with this lamp. As a result, the luminous flux ratio at the same input is higher by about 1%. Became. In these examples, the pipe diameter of the b portion is thickened and the coldest portion is formed in the b portion. On the other hand, when the pipe diameter of the b portion is the same as that of the a portion, the coldest portion occurs at the pipe end, in which case, as the lamp is lit, the electrode material is scattered and the pipe end is colored and the coldest portion is produced. The temperature of the part changed and the efficiency of the lamp decreased accordingly.

[0009]

According to the present invention, the output of the ring-shaped fluorescent lamp can be improved with a simple structure, and the decrease in output over time due to lighting can be suppressed.

[Brief description of drawings]

FIG. 1 is a plan view of a discharge tube of an annular fluorescent lamp according to the present invention.

[Explanation of symbols]

 1 ... Discharge tube, 2a, 2b ... Electrode.

Claims (1)

[Claims] 1. A ring-shaped fluorescent lamp, wherein a part of the ring-shaped fluorescent lamp excluding an electrode portion has a large diameter.