JP5163336B2 - Fluorescent lamp - Google Patents

Description

  The present invention relates to a fluorescent lamp.

  It is generally known that when the temperature of a fluorescent lamp rises due to various factors, the vapor pressure of mercury enclosed in the arc tube becomes excessive and the luminous efficiency is lowered. As a countermeasure for this, a method of controlling the vapor pressure of mercury in the arc tube using the change in characteristics due to mercury alloying (amalgam) and the coldest part temperature formed in the arc tube is used.

In the case where the vapor pressure of mercury is controlled by the coldest part, if the coldest part temperature rises, the light emission efficiency also decreases. Therefore, for example, as disclosed in Patent Document 1, there has been proposed a fluorescent lamp in which electrodes provided at both ends have different electrode heights from the tube end. As a result, the coldest part is formed at the end of the arc tube on the side where the electrode having a relatively high electrode height is provided, thereby suppressing the temperature rise of the coldest part and preventing the light emission efficiency from being lowered. ing.
JP 2000-323094 A

  However, since mercury has a property of gathering at the coldest part, the above-described fluorescent lamp has an uneven distribution of mercury in the arc tube. In such a case, until the arc tube temperature rises sufficiently after the lamp is lit, the entire arc tube does not reach the proper mercury vapor pressure due to the delay in diffusion of mercury vapor from the coldest part. There may be a problem that discharge is not performed. This tendency was particularly noticeable outdoors in winter when the ambient temperature is low.

  Therefore, an object of the present invention is to provide a fluorescent lamp that eliminates the unevenness of mercury in the arc tube and prevents an abnormal discharge state that occurs immediately after lighting.

  In order to achieve the above-described object, a fluorescent lamp of the present invention includes a light emitting tube in which a phosphor layer is formed on an inner surface and a discharge medium containing mercury and a rare gas is sealed in an airtightly sealed internal space. A pair of electrodes provided at both ends of the arc tube and having different electrode heights from the tube end of the arc tube, and the first of the pair of electrodes having a relatively high electrode height; An electrode is provided at the first end of the arc tube, and a second electrode having a relatively low electrode height is provided at the second end of the arc tube, and the first of the arc tube Is thicker than the thickness of the arc tube on the second end side.

  As described above, according to the present invention, it is possible to provide a fluorescent lamp that eliminates the unevenness of mercury in the arc tube and prevents an abnormal discharge state that occurs immediately after lighting.

  Hereinafter, embodiments of the fluorescent lamp of the present invention will be described with reference to the drawings.

  First, an embodiment in which the present invention is applied to an annular fluorescent lamp 10 is shown in FIG. FIG. 1A is a schematic plan view of the fluorescent lamp 10, and FIGS. 1B, 1C, and 1D are lines AA 'and B- in FIG. 1A, respectively. It is a schematic sectional drawing of a B 'line and CC' line.

  The fluorescent lamp 10 according to the present embodiment includes an arc tube 11 having a phosphor layer formed on the inner surface, and a pair of electrodes 14 and 15 provided at both ends 12 and 13 of the arc tube 11.

  The arc tube 11 is formed of a glass tube whose inner space is hermetically sealed by stems 16 and 17 provided at both end portions 12 and 13, and a discharge medium containing mercury and a rare gas is enclosed in the inner space. ing. Further, a ring shape is formed by a base 19 provided so as to surround both ends thereof.

  The electrodes 14 and 15 are configured as filament electrodes provided at the distal ends of lead wires 18 inserted into the arc tube 11 through stems 16 and 17. The electrodes 14 and 15 are arranged so that the electrode heights H1 and H2 from the tube end of the arc tube 11 are different from each other. The first end 12 of the arc tube 11 is provided with a first electrode 14 having a relatively high electrode height H1, and the second end 13 of the arc tube 11 has a relative height of electrode H2. A low second electrode 15 is provided. For this reason, the coldest part is formed on the first end 12 side, and excess mercury that is not vapor in the arc tube 11 is biased to the vicinity of the coldest part, that is, the first end 12 side.

  In the present embodiment, the thickness of the glass tube forming the arc tube 11 is gradually increased from the second end 13 to the first end 12 as can be seen from FIG. 1 (b) to FIG. 1 (d). It is formed to be thick.

  Since the heat capacity of the glass tube increases as the thickness of the glass tube increases, the arc tube 11 in this embodiment has a heat capacity on the first end 12 side where the coldest portion is formed, on the second end 13 side. It will be larger than the heat capacity.

  For this reason, when the temperature of the arc tube 11 is lowered after the lamp is turned off, the second end 13 side having a smaller heat capacity than the first end 12 side where the coldest part is formed and excess mercury is collected. Will begin to fall first. When the temperature on the second end portion 13 side is lower than the boiling point of mercury, mercury that has become vapor in the arc tube is liquefied and condensed on the phosphor surface from the second end portion 13 side. Further, as the overall temperature decreases, the condensation of mercury moves toward the first end 12 side.

  In this manner, the arc tube 11 is sufficiently formed by condensing mercury on the second end 13 side before the first end 12 side on which the coldest part is formed and excess mercury is collected. After cooling, the mercury is distributed in a well-balanced manner throughout the arc tube 11. As a result, at the next lighting, an appropriate mercury vapor pressure can be obtained without causing a delay in the diffusion of the mercury vapor even immediately after the lighting, and normal discharge is performed.

  Further, since the thickness of the arc tube 11 is gradually increased from the second end portion 13 to the first end portion 12, the temperature of the arc tube 11 during lamp operation is the first coldest portion. It gradually rises from the end 12 side to the second end 13 side. Due to this temperature gradient, even when the lamp is lit, surplus mercury is not concentrated in the vicinity of the coldest part but is gently distributed in the arc tube 11, which is more effective.

  Here, as shown in FIG. 1B to FIG. 1D, it is more preferable that the outer peripheral side wall thickness is increased from the first end portion 12 of the arc tube 11.

  Since the first electrode 14 has a relatively high electrode height H1, it is necessarily close to the tube wall on the outer peripheral side of the glass tube. For this reason, the temperature of the outer peripheral side of the glass tube is higher than that of the inner peripheral side. By increasing the thickness on the outer peripheral side over the first end portion 12, it is possible to suppress the temperature rise of the tube wall on the outer peripheral side in the vicinity of the coldest part and sufficiently reduce the temperature of the coldest part. As a result, not only a reduction in luminous efficiency can be prevented, but also a more effective temperature gradient can be realized that prevents the deviation of mercury from the first end portion 12 to the second end portion 13.

  In the fluorescent lamp 10 of the present embodiment, the straight tube-shaped glass tube is heated to the softening point or higher to form an annular glass tube, but the length of the glass tube becomes longer due to the softening. . At that time, the balance of elongation of the glass tube is intentionally lost by changing the heating temperature between the inner peripheral side and the outer peripheral side and further creating a temperature difference depending on the site in the length direction. In this manner, the thickness of the arc tube 11 can be changed in the length direction and the circumferential direction.

  Next, a case of a straight tube type fluorescent lamp 20, which is another embodiment of the present invention, will be described with reference to FIG.

  2A is a schematic perspective view of a straight tube fluorescent lamp 20, and FIGS. 2B, 2C, and 2D are respectively DD ′ in FIG. 2A. It is a schematic sectional drawing of a line, EE 'line, and FF' line.

  Similarly, in the fluorescent lamp 20 of the present embodiment, in the arc tube 21, the thickness on the first end portion 22 side where the first electrode 24 having a relatively high electrode height H1 is provided has an electrode height H2. Is thicker than the wall thickness on the second end portion 23 side where the second electrode 25 is relatively low. Thereby, the same effect as the above-mentioned embodiment can be obtained, the unevenness of mercury can be eliminated, and abnormal discharge immediately after lighting can be prevented.

  In the case of a straight tube type fluorescent lamp, as shown in FIG. 2, the arc tube is not only formed from one glass tube prepared so that the wall thickness gradually changes. As shown in FIG. 3 and FIG. 4, it may be formed of two glass tubes 31a and 31b having different thicknesses.

  When the arc tube 31 is formed of two glass tubes, the thick glass tube 31a is provided with the first electrode 24 having a relatively high electrode height H1, and the thin glass tube 31b. The second electrode 25 having a relatively low electrode height H2 is provided (see FIG. 3). By joining these two glass tubes 31a and 31b on the side where the electrodes 24 and 25 are not provided, one arc tube 31 (see FIG. 4) is formed.

  Not limited to the above-described embodiment in which the thickness of the arc tube is changed, but as a means for providing a difference in temperature drop at both ends of the arc tube at the time of extinction, it is formed on the inner surface without changing the thickness of the arc tube. It is also possible to change the thickness of the phosphor layer. In some cases, in order to realize a more effective temperature gradient, the thickness of the phosphor layer may be changed after changing the thickness of the arc tube. As a result, the same effect as when the thickness of the arc tube is changed can be obtained.

It is the top view and sectional drawing which show schematically the fluorescent lamp in embodiment of this invention. It is the perspective view and sectional drawing which show schematically the fluorescent lamp in other embodiment of this invention. It is the perspective view and sectional drawing which show schematically the arc tube which comprises the modification of the fluorescent lamp in other embodiment of this invention. It is a perspective view which shows roughly the modification of the fluorescent lamp in other embodiment of this invention.

Explanation of symbols

10, 20 Fluorescent lamp 11, 21, 31 Arc tube 12, 22 First end 13, 23 Second end 14, 24 First electrode 15, 25 Second electrode H1, H2 Electrode height

Claims (7)

An arc tube in which a phosphor layer is formed on the inner surface and a discharge medium containing mercury and a rare gas is sealed in an airtightly sealed internal space, and provided at both ends of the arc tube, the tube ends of the arc tube A pair of electrodes having different electrode heights from each other,
Of the pair of electrodes, a first electrode having a relatively high electrode height is provided at a first end of the arc tube, and a second electrode having a relatively low electrode height is the light emission. Provided at the second end of the tube;
A fluorescent lamp in which a thickness on the first end side of the arc tube is thicker than a thickness on the second end side of the arc tube.   The fluorescent lamp according to claim 1, wherein the arc tube has a ring shape.   The fluorescent lamp according to claim 2, wherein a thickness of the arc tube gradually increases from the second end portion to the first end portion.   4. The fluorescent lamp according to claim 3, wherein a thickness of an outer peripheral side of the arc tube gradually increases from the second end portion to the first end portion.   The fluorescent lamp according to claim 1, wherein the arc tube has a straight tube shape.   The fluorescent lamp according to claim 5, wherein a thickness of the arc tube gradually increases from the second end portion to the first end portion.   The fluorescent lamp according to claim 5, wherein the arc tube is formed of two glass tubes having different thicknesses.

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