JP2005026087A - Arc tube and electrodeless fluorescent lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an arc tube capable of reducing transparency and suppressing degradation of light flux, without using a shallower recess of a discharge container, or forming a fluorescent layer at the bottom of the recess. <P>SOLUTION: The arc tube 12 uses a discharge container 16 having a recess 14 recessing inwardly in a wall surface. Fluorescent layers 35a, 35b are formed on an inner wall surface of the discharge container 16. The thickness t (μm) of the fluorescent layer 35a in a portion (area A1) in opposition to the bottom 18 of the recess 14 is set to 180/d≤t≤20 (d≥9 mm), where d (mm)is a minimum distance between the bottom 18 of the recess 14 and the portion of the inner wall surface of the discharge container 16, in opposition to the bottom 18. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to an arc tube in which a fluorescent layer is formed on the inner surface of a discharge vessel having an inward recessed portion on a wall surface, and an electrodeless fluorescent lamp including the arc tube.
[0002]
[Prior art]
Since the electrodeless fluorescent lamp does not have an electrode that determines the life of a general fluorescent lamp, the electrodeless fluorescent lamp exhibits a long life characteristic superior to that of a general fluorescent lamp. This electrodeless fluorescent lamp (hereinafter simply referred to as “lamp”) includes, for example, an arc tube having a fluorescent layer formed on the inner surface of a glass discharge vessel having an inwardly recessed portion on a wall surface, and an indented portion. And an excitation coil inserted in the.
[0003]
When the lamp is lit, a high-frequency alternating current is passed through the excitation coil to generate an alternating magnetic field in the arc tube, thereby forming an inert gas and mercury gas plasma sealed inside the arc tube. The fluorescent layer is excited by ultraviolet rays generated in the light to generate visible light (see Patent Document 1).
The fluorescent layer is formed on the inner surface of the discharge vessel other than the bottom of the recessed portion. This is because the bottom of the recessed portion of the discharge vessel is provided with an exhaust pipe that is used when exhausting the inside of the discharge vessel or sealing the above-mentioned gas, forming a fluorescent layer on the bottom of the recessed portion. This is because the exhaust pipe is narrow and may be clogged (the through hole is blocked).
[0004]
[Patent Document 1]
[Patent Document 1] Japanese Patent Laid-Open No. 9-185556
[Problems to be solved by the invention]
In such a lamp using a conventional arc tube, when the lamp is lit, the bottom of the recessed portion can be seen through from the outside of the arc tube (this bottom is referred to as “see-through” hereinafter). There is a problem that the appearance design of the arc tube during lighting is significantly reduced.
[0006]
This problem of see-through can be solved by, for example, making the recessed portion shallow or forming a thick fluorescent layer, but the former is difficult to control the coldest spot temperature in the arc tube during lighting, and the latter Will reduce the luminous flux emitted from the arc tube.
The present invention has been made in view of the above-described problems, and can improve the see-through without shallowing the recessed portion of the discharge vessel or forming a fluorescent layer on the bottom of the recessed portion. An object of the present invention is to provide an arc tube capable of suppressing a decrease in luminous flux and an electrodeless fluorescent lamp using the arc tube.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the arc tube according to the present invention has a fluorescent layer formed on the inner surface of a discharge vessel having an inward recessed portion on a wall surface, the bottom of the recessed portion, and the discharge vessel The thickness t (μm) of the fluorescent layer formed on the inner surface of the portion facing the bottom of the recessed portion, where d (mm) is the shortest distance from the portion facing the bottom of the recessed portion. But,
180 / d ≦ t ≦ 20 (however, d ≧ 9 mm)
It is characterized by satisfying.
[0008]
Here, d ≧ 9 mm is set because the above formula is not established when d is smaller than 9 mm. According to this, it is possible to reduce the see-through and to suppress the decrease in the luminous flux.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of an electrodeless fluorescent lamp according to the present invention will be described with reference to the drawings.
1. FIG. 1 is a front view showing the entire structure of the electrodeless fluorescent lamp according to the present invention, with a part thereof cut away. The electrodeless fluorescent lamp (hereinafter simply referred to as “lamp”) 10 utilizes a so-called electromagnetic inductively coupled discharge (H discharge). Further, the lamp 10 described below has a 20 W product corresponding to the general incandescent lamp 100 W, that is, the lamp power is 20 W.
[0010]
The lamp 10 has an arc tube 12 made of translucent glass. The arc tube 12 includes a discharge vessel 16 having a recessed portion 14 recessed inward (downward) on a wall surface, and fluorescent layers 35 a and 35 b are formed on the inner surface of the discharge vessel 16. Further, mercury (Hg) and an inert gas such as krypton (Kr) gas are sealed in the discharge space 34 inside the discharge vessel 16 as a discharge substance.
[0011]
In FIG. 1, the fluorescent layer formed on the outer peripheral surface of the recessed portion 14 is denoted by reference numeral “35b”, and the fluorescent layer formed on the inner surface of the discharge vessel 16 other than the recessed portion 14 is denoted by reference numeral “35a”. ".
The recessed portion 14 has a bottomed cylindrical shape, and an exhaust pipe 17 used when exhausting the inside of the discharge vessel 16 or sealing the above-described gas is provided outward (upward) on the bottom 18. ) To extend. An excitation coil unit 20 is inserted in the recessed portion 14.
[0012]
The excitation coil unit 20 includes a core 21 and an excitation coil 22 wound around the outer periphery of the core 21. An extending portion 26 of an aluminum heat sink 25 is inserted on the inner peripheral side of the excitation coil unit 20 as a heat dissipation means for preventing the temperature of the core 21 from rising when a current is passed through the excitation coil 22.
The extending portion 26 is opened along the axis thereof, and the exhaust pipe 17 of the arc tube 12 is inserted into the opening. The heat sink 25 has a cup-shaped portion 27 extending to the extending portion 26, and the cup-shaped portion 27 is fixed to a case 28 made of synthetic resin.
[0013]
The case 28 is connected to the excitation coil 22 and houses a high-frequency drive circuit 30 for flowing a high-frequency alternating current through the excitation coil 22. Further, a base 31 having the same standard as that of a general incandescent bulb is attached to the case 28, and electric power from a commercial power source is supplied to the high frequency driving circuit 30 through the base 31.
2. Regarding the arc tube The arc tube 12 has, for example, the shape of an arc tube used in a general incandescent bulb or a bulb-type fluorescent lamp, for example, A shape. The discharge vessel 16 has, for example, a spherical shape with respect to the shape of the arc tube 12, and specific dimensions thereof include, for example, a maximum outer diameter D1 of 75 mm and a total length L2 as shown in FIG. 90 mm. On the other hand, specific dimensions of the recessed portion 14 are, for example, an outer diameter D2 of 21 mm and an overall length L1 of 70 mm.
[0014]
The exhaust pipe 17 provided on the bottom 18 of the recessed portion 14 is used when the inside of the discharge vessel 16 is evacuated or when the above-described discharge substance is sealed, and then, for example, chip-off sealed. As a result, a sealed discharge space 34 is formed in the discharge vessel 16.
The discharge vessel 16 has a bottom 19 located on an extension of the direction in which the recessed portion 14 is recessed (below in FIG. 1 and hereinafter simply referred to as “recessed direction”), and the bottom 18 of the recessed portion 14 and the discharge vessel. The distance between the bottom 16 and the bottom 19 in the recessed direction is about 20 mm (L2-L1), and the shortest distance d (see FIG. 1) between the bottom 18 and the discharge vessel 16 is about 18 mm.
[0015]
A protective layer is formed on the inner surface of the discharge vessel 16 excluding the bottom 18 of the recessed portion 14, and the above-described fluorescent layers 35a and 35b are formed thereon. In FIG. 1, the protective layer is not shown.
The protective layer is for preventing sodium from eluting from the glass discharge vessel 16 during lighting. The reason for preventing sodium elution is that when sodium is eluted, it is combined with mercury enclosed in the discharge space 34 to become amalgam, which adheres to the inner surface of the discharge vessel 16, the protective layer or the fluorescent layer 35. This is because the luminous flux decreases.
[0016]
For this protective layer, for example, one kind of alumina particles, silica particles, yttria particles, and lanthanum particles, specifically, alumina particles are used. The thickness of the protective layer is approximately 1 μm on the inner surface of the discharge vessel 16 excluding the recessed portion 14, and approximately 10 μm on the peripheral surface of the recessed portion 14.
The reason why the protective layer on the peripheral surface of the recessed portion 14 is thick is to reflect the visible light emitted when the fluorescent layer 35 is excited to the outside of the arc tube 12. Note that titania particles may be used when the protective layer is made thick so as to have a reflecting action.
[0017]
As the fluorescent layer 35, for example, a mixture of three types of light emitters of red, green, and blue (for three wavelength regions) is used. Specifically, europium inactive yttrium oxide (Y ₂ O ₃ : Eu ³⁺ ) in red, cerium / terbium inactive lanthanum phosphate (LaPO ₄ : Ce ³⁺ , Tb ³⁺ ) in green, and europium inactive in blue Active barium magnesium aluminate (BaMg ₂ Al ₁₀ O ₁₇ : Eu ²⁺ ) or the like is used.
[0018]
The film thickness of the fluorescent layer 35a is a surface around the bottom 19 of the discharge vessel 16, specifically, a surface located below the bottom 18 of the recessed portion 14, that is, on the bottom 19 side of the discharge vessel 16 (FIG. 1). Then, it corresponds to the range A1).
On the other hand, the surface located above the bottom 18 of the recessed portion 14 (shown as a range A2 in FIG. 1 and corresponding to a range excluding the range A1 from the inner surface of the discharge vessel) is formed to be approximately 30 to 60 μm. . In addition, the film thickness of the fluorescent layer 35b on the outer periphery of the recessed portion 14 is approximately 12 to 25 μm.
[0019]
3. Regarding the film thickness of the fluorescent layer in the outer tube range A1, (1) the lower limit When the arc tube 12 is caused to emit light, the bottom 18 of the recessed portion 14 of the discharge vessel 16 is transparent through the periphery of the bottom 19 of the discharge vessel 16 This is probably because the fluorescent layer 35a formed on the bottom is thin or the recessed portion 14 is deep (that is, the distance between the bottom 19 of the discharge vessel 16 and the bottom 18 of the recessed portion 14 is small).
[0020]
For this reason, the inventors investigated the film thickness (film thickness in the range a1) of the fluorescent layer 35a in which the see-through occurs when the shortest distance d between the range A1 and the bottom 18 of the recessed portion 14 is changed.
Specifically, the arc tube 12 is manufactured by setting the shortest distance d to 10 mm, 20 mm, and 30 mm, and changing the thickness of the fluorescent layer 35a on the bottom 19 of the discharge vessel 16 for each shortest distance d. Whether or not the bottom 18 of the recessed portion 14 can be seen when the arc tube 12 in this state is viewed from above, the lamp using the No. 12 is lit with the base 31 down (so-called “under-base lighting”). Was tested.
[0021]
FIG. 2 is a diagram showing the test results described above.
As shown in the figure, the test results show that when the film thickness of the fluorescent layer 35a is large at each shortest distance d, no see-through occurs, and between the film thickness at which the see-through occurs and the film thickness at which no see-through occurs. It is considered that there is a boundary line.
The thickness t (μm) of the fluorescent layer where no see-through occurs at each shortest distance d is the shortest distance d (mm) between the bottom 18 of the recessed portion 14 and the bottom 19 side of the discharge vessel 16 facing the bottom 18. Then,
t ≧ 180 / d
It can be expressed as
[0022]
(2) With regard to the upper limit, it has been proved by the above-described test that the transparency of the bottom 18 of the recessed portion 14 can be eliminated by increasing the thickness of the fluorescent layer 35a. It will decline. Therefore, the inventors conducted a test to investigate the relationship between the thickness of the fluorescent layer 35a formed on the inner surface of the discharge vessel 16 and the luminous flux emitted from the lamp using the arc tube having the thickness of the fluorescent layer 35a. went.
[0023]
The test was conducted by changing the film thickness of the fluorescent layer 35a between 12 μm and 18 μm and measuring the luminous flux of the arc tube at that time.
The lamp lighting conditions are shown below.
Lighting condition ... Temperature when lighting on the base ... 25 ℃ ± 1 ℃
Measurement time: measured when 100 hours have elapsed since the lamp was lit. FIG. 3 is a diagram showing the results of the above test. In FIG. 3, the vertical axis represents the ratio of the measurement result to the target luminous flux. The luminous flux with a luminous flux ratio of 100% is a value set as a target in managing the luminous flux of the lamp.
[0024]
In addition, the measurement of the film thickness of the fluorescent layer was performed using SEM (Scanning Electron Microscope).
As shown in the figure, when the film thickness of the fluorescent layer is 12.5 μm and 14.5 μm, the emitted light beam is substantially the target emitted light beam, but when the film thickness is 14.5 μm or more, the test results are as follows. It can be seen that the luminous flux ratio decreases as the film thickness increases.
[0025]
It is considered that about 95% of the decreasing luminous flux is required from the viewpoint of quality with respect to the target luminous flux. Therefore, it can be estimated from FIG. 3 that the thickness of the fluorescent layer that is 95% or less with respect to the target luminous flux is larger than about 20 μm.
(3) Summary From the above, the thickness of the fluorescent layer that can eliminate the see-through and suppress the decrease in the luminous flux is the bottom 18 of the recessed portion 14 and the bottom surface of the recessed portion 14 on the inner surface of the discharge vessel 16. The thickness t () of the fluorescent layer formed on the peripheral surface of the bottom 19 of the discharge vessel 16 facing the bottom 18 of the recessed portion 14, where d (mm) is the shortest distance from the portion facing the surface 18. μm)
180 / d ≦ t ≦ 20 (however, d ≧ 9 mm) (1)
Satisfy your needs.
[0026]
Accordingly, the film thickness t of the fluorescent layer 35a in the range A1 is approximately 18 μm in the above description, but is not limited to this value, and may be any value that satisfies the above formula 1.
4). With regard to the method for forming the fluorescent layer, in the above-mentioned 3, the bottom 18 of the recessed portion 14 is not visible from the outside even when the lamp is lit, and it is possible to suppress the decrease in the luminous flux when the lamp is lit. The range of the film thickness of the fluorescent layer 35a has been described. Here, a method for forming the fluorescent layer 35a so that the film thickness of the fluorescent layer 35a is within the optimum range will be briefly described.
[0027]
FIG. 4 is a schematic view for explaining a process of forming a fluorescent layer on the inner wall of the outer tube constituting the discharge vessel.
First, the outer tube 40 constituting the discharge vessel is prepared. The outer tube 40 has a portion that becomes the discharge vessel 16 described above, and has a configuration in which a cylindrical portion 41 and a substantially spherical portion 42 are connected.
[0028]
Then, as shown in FIG. 4A, the injection nozzle 50 is caused to enter the outer tube 40 with the cylindrical portion 41 facing upward, and the coating solution 43 is supplied from the injection nozzle 50. Inject into the outer tube 40. The coating solution 43 is, for example, a mixture of phosphor powder in an aqueous solution in which polyethylene oxide (a paste-like polymer substance) is dissolved in pure water.
[0029]
Next, the outer tube 40 is gradually inverted while being rotated in the direction of arrow A as shown in FIG. Here, the outer tube 40 is rotated so that the coating solution 43 is applied (applied) to the substantially entire inner surface of the substantially spherical portion 42 and the coating solution 43 does not remain on the inner surface of the outer tube 40 in a streak shape. It is to do.
Then, as shown in FIG. 4C, after the outer tube 40 is completely inverted, after a while, the rotation of the outer tube 40 is stopped, and the hot tube is arranged below the hot air duct 51 from which hot air is blown out. To do. At this time, the outer tube 40 is maintained in an inverted state. At this time, a blower cylinder 52 that blows warm air into the outer tube 40 is entered from below.
[0030]
The outer tube 40 receives hot air set to a predetermined temperature, blown out from the outlet of the hot air duct 51, from the outer surface of the bottom of the outer tube 40 for a predetermined time, and is shown in FIG. As described above, the hot air from the blower cylinder 52 is applied to the coating liquid 43 to dry it.
In the above fluorescent layer forming process, the viscosity and components of the coating liquid 43 and the temperature of hot air or hot air blown out from the hot air duct 51 and the blower cylinder 52 have not been described in detail. Thus, the thickness of the fluorescent layer changes. Therefore, management of the film thickness of the fluorescent layer is appropriately determined while confirming the above-mentioned coating conditions through tests and the like.
[0031]
In addition, the film thickness can be managed even if the formation method of a fluorescent layer does not pass through the above-mentioned process. For example, even when the viscosity of the coating solution containing the fluorescent layer is lowered and the coating solution is applied several times, it can be formed into a predetermined film thickness.
5. Others (1) Regarding the distance between the bottom of the discharge vessel and the bottom of the recessed portion, that is, the distance in the recessed direction between the bottom 19 of the discharge vessel 16 and the bottom 18 of the recessed portion 14 when the lamp power is 20 W Is approximately 20 mm, but this distance is preferably 18 mm or more and 23 mm or less. That is, when the distance is smaller than 18 mm, the coldest spot temperature becomes lower than the optimum temperature, and conversely when the distance is larger than 23 mm, the coldest spot temperature becomes higher than the optimum temperature. It is because it falls.
[0032]
When the distance in the recess direction between the bottom 19 of the discharge vessel 16 and the bottom 18 of the recess 14 is 18 mm, the shortest distance d between the bottom 19 of the discharge vessel 16 and the bottom 18 of the recess 14 is about 17 mm. It is considered to be.
(2) Lamp power In the above embodiment, an electrodeless fluorescent lamp having a lamp power of 20 W has been described. However, the present invention is not limited to a lamp power of 20 W. For example, the lamp power may be smaller than 20W, and conversely, it may be larger than 20W.
[0033]
However, in order to manage the coldest spot temperature of the electrodeless fluorescent lamp in an optimum range, the distance in the recess direction between the bottom of the discharge vessel and the bottom of the recess varies depending on the lamp power, but is generally 12 mm or more and 30 mm. The following range is considered preferable. At this time, the shortest distance between the bottom of the discharge vessel and the bottom of the recessed portion (the shortest distance between the bottom of the recessed portion and the inner surface of the discharge vessel facing the bottom of the recessed portion) is approximately 11 mm. It is considered to be about.
[0034]
【The invention's effect】
As described above, the arc tube according to the present invention has a fluorescent layer formed on the inner surface of a discharge vessel having an inwardly recessed portion on a wall surface, the bottom of the recessed portion and the inner surface of the discharge vessel. When the shortest distance from the portion facing the bottom of the recessed portion is d (mm), the thickness t (μm) of the fluorescent layer formed in the portion facing the bottom of the recessed portion is
180 / d ≦ t ≦ 20 (however, d ≧ 9 mm)
Meet. Thereby, without making the recessed part of a discharge vessel shallow, a see-through | permeability can be lost and the fall of the emitted light beam can also be suppressed.
[Brief description of the drawings]
FIG. 1 is a front view showing an overall configuration in which a part of an electrodeless fluorescent lamp according to an embodiment of the present invention is cut away.
FIG. 2 is a diagram showing the relationship between the shortest distance between the bottom of the discharge vessel and the bottom of the recessed portion and the occurrence of see-through of the bottom of the recessed portion in the embodiment of the present invention.
FIG. 3 is a diagram showing the relationship between the thickness of the fluorescent layer at the bottom of the discharge vessel and the luminous flux ratio in the embodiment of the present invention.
FIG. 4 is a diagram illustrating a process of forming a fluorescent layer on the inner wall of an outer tube constituting a discharge vessel.
[Explanation of symbols]
10 lamp 12 arc tube 14 recessed portion 16 discharge vessel 18 bottom of recessed portion 19 bottom of discharge vessel d shortest distance

Claims (5)

An arc tube in which a fluorescent layer is formed on the inner surface of a discharge vessel having an inward recessed portion on a wall surface,
When the shortest distance between the bottom of the recessed portion and the portion of the inner surface of the discharge vessel facing the bottom of the recessed portion is d (mm), it is formed at a portion facing the bottom of the recessed portion. The thickness t (μm) of the fluorescent layer is
180 / d ≦ t ≦ 20 (however, d ≧ 9 mm)
An arc tube characterized by satisfying 2. The light emitting device according to claim 1, wherein the discharge vessel has a bottom substantially extending from the recessed portion, and a portion facing the bottom of the recessed portion is a surface near the bottom of the discharge vessel. tube. The discharge vessel has a bottom on a substantially extension of the recessed portion, and a portion facing the bottom of the recessed portion is a surface located on the bottom side of the discharge vessel with respect to the bottom of the recessed portion. The arc tube according to claim 1. The arc tube according to any one of claims 1 to 3, wherein a distance between a bottom of the recessed portion and a bottom of the discharge vessel is 18 mm or more and 23 mm or less. An electrodeless fluorescent lamp comprising the arc tube according to any one of claims 1 to 4.

Images