JPS5968162A - Low pressure sodium lamp - Google Patents

Abstract

PURPOSE:To enable instantaneous buring to be performed and enable a sufficient luminous flux to be obtained instantaneously by forming a discharge space in an inner tube which is installed in an outer tube and has open ends, providing a relatively large non-discharge space around the inner tube, and adjusting the mean potential gradient of the positive column observed during maintenance of electric discharge in the discharge space to over a specified value. CONSTITUTION:A low pressure sodium lamp is constituted of a cylindrical outer tube 1 forming an airtight space, a cylindrical inner tube 2 which is installed almost in the center of the outer tube 1 and has an axis coinciding with that of the outer tube 1, and a heat-insulating over tube 3 which covers the outer tube 1 and consists of a transparent glass tube. A pair of electrodes 4 and 4 are installed at the open ends of the inner tube 2. The internal space of the inner tube 2 works as a discharge space (A) and the internal space of the outer tube 1 excluding the space (A) works as a non-discharge space (B). The outer surface area (Sa) of the inner tube 2 forming the discharge space (A) and the outer surface area (Sb) of the outer tube 1 forming the non-discharge space (B) are adjusted to satisfy the relationship of Sb>=5.Sa. The mean potential gradient (E) of the positive column observed during maintenance of electric discharge in the discharge space (A) is adjusted to E>=1.5V/cm. Sodium vapor is used as the main discharge (emission) matter.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a completely new low-pressure sodium lamp that has high brightness and provides a large luminous flux.

(Background Art) High-pressure metal vapor discharge lamps such as mercury lamps and high-pressure 1-lium lamps have been realized and put into practical use as discharge lamps that have high brightness and large luminous flux (M).

However, this type of discharge lamp is designed to operate at high pressure and high temperature during constant lighting, so the inside of the tube remains at low temperature and low pressure for several minutes after lighting starts, as shown in Figure 1 It requires a so-called warm-up time (time from O to L1 in the figure) where there is insufficient light, and
If you try to turn on the I'll N after it has been turned off, it will not be possible to restart it due to the high temperature and pressure inside the tube, and it will take several minutes after the light goes off before it can be restarted (in the same figure).
It has the disadvantage that it requires t2~b). Furthermore, even if you try to obtain the desired light color and color temperature, it is difficult to obtain a practically usable discharge (
Since the number of light-emitting (light-emitting) substances is limited to a few types, specific light colors,
There is also the drawback that the color temperature is the same, making it difficult to design freely. Furthermore, due to the high temperatures, ordinary soft glass cannot be used and processing is difficult. Particularly in high-pressure sodium lamps, the activity of thorium becomes stronger at high pressure, making it impossible to use even quartz as a tube material, making it extremely expensive. Polycrystalline alumina ceramic has to be used, which has the disadvantage of being extremely valent.

(Objective of the Invention) The present invention has been made in view of the drawbacks mentioned above, and its purpose is to operate at low pressure even during steady lighting, and to operate under low pressure even during steady lighting.・To provide a sodium lamp that can produce instantaneous production with iI!+ brightness, large luminous flux, and good light color and color temperature.

(Disclosure of the Invention) The essential structure of the present invention is shown in FIG. A tutorium lamp according to the present invention includes a cylindrical outer tube 1 forming an airtight space, a concentric cylindrical inner tube 2 disposed approximately at the center of the outer tube 1, and a concentric cylindrical inner tube 2 that covers the outer tube 1. It consists of a cover tube 3 made of a transparent glass cage for heat retention, and both ends of the inner tube 2 are open, and a pair of electrodes 4, 4 are disposed in both openings, and a discharge is generated inside the inner tube 2. Space A is designated as space A, and other spaces within outer tube 1 are designated as non-discharge space B.
shall be. Then, the outer surface area forming the discharge space, that is, the outer surface area Sa of the inner tube 2, and the outer surface area Sh forming the non-discharge space 13, that is, the outer surface area Sh of the outer tube 1, is set as sb≧5·Sa, and the discharge space Discharge silk in A: The average positive column potential gradient over time [L is ≧1.5 V/cm], and the main discharge (luminescence) substance is thorium vapor.

Note that the shapes of the outer tube 1, inner tube 2, and cover tube 3 do not have to be cylindrical as described above, and the outer tube 1 and the cover tube 3 (
For example, the inner tube 2 may have a shape similar to that of current high-pressure lithium lamps, the inner tube 2 may be bent, the opening need not be limited to the above configuration, and the outer tube 1 and the inner tube 2 may be the same. It is sufficient to provide an opening that is airtight.

Next, the operating principle and effects of such a sodium lamp will be explained. First, since the 1-lium lamp according to the present invention is a low-pressure metal vapor discharge as mentioned above, its operating principle is essentially the same as that of a fluorescent lamp, and it reaches sufficient brightness immediately after starting. You can also turn the lights on again after they go out. M) This is because the non-discharge space B is extremely wide compared to the discharge space.
b≧5·Sa) and since each discharge space Δ, B is airtight, the lowest temperature of the metal vapor is sufficiently lower than the temperature inside the discharge space, and highly efficient radiation can be maintained. In other words, if the ratio of the non-discharge space B to the discharge space Δ (referred to as B/A) is changed, of course the outer surface area S of the discharge space Δ and the non-discharge space B
Although it depends on a, Sb, and the envelope shape, if these are fixed as typical shapes, the characteristics shown in FIG. 3 can be obtained. In the figure, Ta indicates the surface temperature of the discharge space Δ, Tb indicates the surface temperature of the non-discharge space B, and Tc indicates the ambient temperature.

Therefore, although the temperature of the discharge space is higher than that of a 1%-tube discharge lamp that only enters the discharge space, the coldest temperature is regulated by the non-discharge space B, so it is lower. and,
The difference becomes larger as the above B/A becomes larger.

This becomes very effective when increasing the lamp input and aiming for high brightness and large luminous flux.

Figure 4 shows the luminous efficiency of visible light at 589 nm and 590 nm (single line), and Figure 5 shows the energy level diagram of sodium atoms. As is well known, the temperature inside the tube is about 270
°C (the corresponding thorium vapor pressure is several mmTorr)
), and the current low-pressure 1-lium lamp is made this way. Although such lamps have high efficiency, they have the drawbacks of being pure yellow with no white appearance, extremely poor color rendering, low brightness, and large size. In order to improve these shortcomings and achieve high brightness and large luminous flux, it is necessary to make the discharge part smaller and increase the lamp power, but if this continues, the temperature inside the tube will rise to an abnormal level, and the low pressure will not be maintained, causing instantaneous damage. It becomes impossible to turn on the light. However, in the present invention, by providing the non-discharge space B@ as described above, the tube coldest temperature can be adjusted to the desired 27°C.
It becomes extremely easy to maintain the temperature close to 0°C, and low-pressure discharge can be maintained and instantaneous lighting becomes possible.

Next, we will explain the numerical limitation (7) (sb≧5・Sa in -1-).The temperature of the outer surface of the heating element is the heat generation f(
1≦U1 (discharge space A in the present invention) If the amount of heat generated (substantially discharge power in the present invention) is constant, it is approximately correlated to the outer surface area of the mature body, so the non-discharge space I
If the outer surface temperature of 3 is 'I''h, the outer surface area is Sh, and the ambient temperature is Tc, if the non-discharge space B approaches a vacuum, the product on the outer surface of the non-discharge space B will decrease. degrees” two rises ΔTb
is approximately Δ゛I″1〕=T b −T c cl−1/S
It becomes b. Therefore, the more people the outer surface fisb of the non-discharge space B, the lower the outer surface temperature 1' IJ of the non-discharge space B.
Is it around? It is close to Wt degree T'c.

Furthermore, since the outer surface of the non-discharge space B to the discharge space is related to the new ambient temperature, if Δ'rao is the 1 degree increase in γIJ in the i13 tube, which is a measure of the discharge space Δ, then
When surrounded by the non-discharge space B, the temperature - of the stomach Δi'a becomes approximately Δ'Fa-ΔTao+Δi'b. Naturally, the larger the outer surface area sb of the non-discharge space B, the closer the outer surface temperature Ta to the 7i discharge space approaches the outer surface/l degree of the 11χ tube, which is only the temperature of the 7i discharge space. become.

In this way, as the outer surface area of the non-discharge space B with respect to the discharge space Δ becomes larger (the larger B/Δ becomes in FIG. 3), the outer surface temperature Tb of the non-discharge space 13 increases At a temperature of 1°C, the outer surface temperature 'Fa to the discharge space approaches the outer surface temperature of a single tube that only enters the discharge space, and (outer surface area Sh of non-discharge space B)'' = (to the discharge space When the outer surface area Sa) is B/
When Δ is 1, the opposite limit is reached, and the outer surface temperature 1'b of the non-discharge space B approaches the outer surface temperature of the small tube due only to the discharge space Δ, and the outer surface temperature Ta of the discharge space A approaches the above single tube. , the outer surface temperature Tb of non-discharge space B and the ambient temperature T
It becomes one novel by adding the '1Tjr degree difference of c. When sb≧5·Sa, the increase in t quality in a single tube due only to the discharge space becomes about 115 or less. However, when trying to obtain a high-intensity, high-output lamp using a conva-l-, generally speaking, if the discharge space is determined by a medium tube with a diameter of △,
The temperature to the discharge space has an extremely high commercial value of 100 to several 100 degrees Celsius, but by setting sb≧5・Sa as shown in section 2, the outer surface temperature 1'b of the non-discharge space B can be reduced. This means that the tube temperature is close to that when a single tube is normally installed and used.

Next, the average positive column potential gradient E during discharge maintenance in the discharge space A will be described. A high positive column potential elongation E means that the electron temperature during discharge, that is, the electron energy is high. However, as is well known in the current low-pressure lamps, the positive column potential gradient IE is 0.5 to I.
V/cm, most of the excitation occurs at the lowest energy level (32P) in the energy level diagram shown in Figure 5, and from that excited level to the ground level (32S)
It was because of the light emission (D line). However, when the positive column potential gradient E is increased to 1.5 V/cm or more, the degree of excitation to higher levels (32D or higher, 4'P or higher, 4'S or higher) increases, and the Radiation increases. Zunawaji: In addition to the D-line, near-ultraviolet light in the 300-nm range and green to red visible light near the D-line become stronger. (j(l is near ultraviolet G', 1 electric power converted into visible light via a phosphor, Don't increase efficiency by 1n,
It is possible to provide a thorium lamp with improved whiteness and better color rendering properties.

In addition, the temperature of the discharge part in such a case is 1f) 1, the number 1
Since the temperature can be maintained at 00°C, the activity of sodium is not as high as that of a high-pressure sodium lamp, so a quartz tube or, in some cases, a hard glass tube can be used.

(Effects of the Invention) As described above, the low-pressure sodium lamp according to the present invention is provided with an inner tube that is formed airtight and has a partial opening [1] inside the outer tube, and the inner tube is used as a discharge space, and the inner tube is formed around the inner tube as a discharge space. A relatively large non-discharge space is provided, the average positive column potential (medium level is 1.5 V/cm or less) during discharge maintenance in the discharge space, and the main discharge material is Therefore, although it is a discharge lamp with high brightness and large luminous flux, it can be turned on instantly, provides sufficient luminous flux instantly, and has good light color and color temperature. It is possible to provide a completely different and new low-pressure thorium lamp.Also, since the temperature of the electrical space is several hundred degrees Celsius at most, the activity of sodium is not as high as that of a high-pressure thorium lamp, and therefore it is possible to provide an expensive polycrystalline thorium lamp. Quartz tube, without using alumina ceramic
It also has the advantage that in some cases, a hard glass tube may be sufficient.

[Brief explanation of drawings]

FIG. 1 is a lighting characteristic diagram of a high-pressure metal vapor discharge lamp, and FIG. 2 is a simplified diagram explaining the basic configuration of the present invention, (a+ is a cross-sectional view,
(hl is a perspective view, FIG. 3 is a tube temperature characteristic diagram of the thorium lamp according to the present invention, and FIG. 4 is a 589 nm, 590 nm
nm (1) line) A diagram showing luminous efficiency of visible light, and FIG. 5 is an energy level diagram of a thorium atom. 1...Outer tube, 2...Inner tube, 3...Cover tube, 4.
...Representative of electrode patent applicant Matsushita Electric Works Co., Ltd. Patent attorney Toshimaru Takemoto (and 2 others) Figure 1 Figure 3 RA Figure 4 Figure 5 Month 1 Itoda L, i, im? (Spontaneous? 1liiD November 11, 1988 1r1 1 City Hall Secretary 1, matter +'l display Show R] 1957 Patent side No. 160535 2, Name of invention Low pressure thorium lamp 3, N lli correction person (related to 71) lli permission applicant address
1048 Kadoma, Kadoma City, Osaka Prefecture Name (58)
3) Matsushita Electric Works Co., Ltd. 7. Tii Iku Kobayashi 4
, Ishiri Person Address Person 1'& J (IF Kadoma City Person Umon Ω1
04th address specification damage S'l”rj respectively called “Glass”? 111 Correct.

Claims (1)

[Claims] (1) an outer tube that is airtight and forms a non-discharge space B;
A non-discharge space with respect to the outer surface area Sδ of the discharge space A, consisting of an inner tube disposed within the outer tube and having an opening in a part and forming a discharge space A, and a heat-retaining cover tube that covers the outer tube. The outer surface area sb of B is sb≧5・Sa, the average positive column potential gradient E during discharge maintenance in the discharge space Δ is E≧1.5V/cm, and the main discharge material is thorium vapor. Low pressure sodium lamp.