JPS6226143B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to a novel high-pressure metal vapor discharge lamp with good color rendering properties. At present, high-pressure mercury lamps have high practical value as highly reliable light sources with the characteristics of high efficiency and long life. However, the average color rendering index of high-pressure mercury lamps is
Its color rendering properties are poor, with an Ra of about 23 (Figure 1 shows the spectral distribution of this high-pressure mercury lamp), and its use is currently limited to specific fields such as outdoor lighting. For this reason, so-called fluorescent high-pressure mercury lamps, in which a layer of red phosphor is applied to the inner wall of the outer tube of high-pressure mercury lamps, have been put into practical use for the purpose of having high efficiency, long life, and improving color rendering properties. However, although the color rendering properties have been gradually improved through the improvement of phosphors and their applied technologies, the average color rendering index Ra is still at a low level of about 53 using only phosphors as an improvement measure. (Figure 2 shows the general spectral distribution of this fluorescent high-pressure mercury lamp.) While phosphors are used to improve color rendering, high-pressure mercury lamps also contain metals other than mercury, such as cadmium, etc. Attempts have been made in the past to add an emission spectrum due to vapor discharge of these metals in addition to the emission spectrum due to mercury vapor discharge to improve color rendering by enclosing zinc. However, in order to obtain a sufficient emission spectrum from cadmium or zinc vapor discharge, it is necessary to increase the vapor pressure of these metals, and therefore it is necessary to set the wall temperature of the arc tube very high. It is necessary to take measures such as increasing the load on the tube wall, and in addition, arc tubes made of quartz are easily attacked by metal vapors such as cadmium or zinc at high temperatures, resulting in cracks in the arc tube and a very short lifespan. Becoming an electric light is edited by W. Elenbaas.
Edited by “High pressure mercuy vapor lancps and
This was a general idea as shown in "Their Applications" (1965) p. 294).The inventors focused only on the color rendering aspect and added cadmium or zinc inside the arc tube. I tried making a high-pressure mercury discharge lamp by adding it, but the average color rendering index was about 60.
(The spectral distribution of a high-pressure mercury discharge lamp containing cadmium is shown in Figure 3.) Furthermore, the management burden was 50% less than that of a normal high-pressure mercury discharge lamp.
% or more, and as a result, a problem occurred in which the arc tube broke after about 1,000 hours of lighting. On the other hand, as a method for improving color rendering,
There are so-called metal halide lamps in which halides of various metals are added to the arc tube so that a high vapor pressure can be obtained without increasing the tube wall temperature that much. However, although this metal halide lamp has become able to obtain good color rendering properties, it is not possible to use alkaline earth metal oxide electrodes with good electron emission properties, and because the halide is sealed in the arc tube, impurity gas is introduced into the tube. Due to the fact that it is easy to carry around, the discharge starting voltage is high, so it cannot be lit with a general high-pressure mercury lamp ballast, and a specially designed ballast must be used. There is. This dedicated ballast is large, heavy, and expensive, and has the disadvantage of not being widely used. As a result of various studies in view of the above points, the inventors applied a luminescent coating on the inner wall of the outer tube, which contains at least a red phosphor that emits maximum light in the wavelength range of 610 to 630 nm, and By sealing at least one of zinc or cadmium in addition to mercury in the tube, color rendering is achieved by the synergistic effect of the emission spectrum caused by the vapor discharge of at least one of the metals, zinc or cadmium, sealed in the tube and the light emission by the phosphor. It has been found that a metal vapor discharge lamp can be obtained which has improved performance and can be operated even with a high-pressure mercury lamp ballast. In other words, by sealing cadmium or zinc inside the arc tube, the emitted light mainly in the blue-green region is supplemented by the emission spectrum caused by the vapor discharge of cadmium or zinc, and the emitted light mainly in the red region is supplemented by the luminescence of the luminescent coating. The color rendition is improved by supplementing the synchrotron radiation, and the improvement in color rendition is not only based on the sum of these radiations, but also due to the synergistic effect of the cadmium or zinc vapor discharge and the luminescent coating. This is because the ratio of the 619 nm emission spectrum due to the luminescent coating to the 546 nm emission spectrum due to mercury vapor discharge, which contributes to improved color rendering properties, is further improved. In addition, this can be seen from Figure 4, which shows the relationship between the ratio of the line spectrum intensity of 619 nm to the line spectrum intensity of 546 nm, depending on the amount of cadmium sealed, obtained by testing with a 400W discharge lamp. It was confirmed that the intensity ratio increased.
In other words, the 619n emitted from the phosphor like this
The fact that the radiation output of the line spectrum of This is thought to be due to this. However, as a result of further investigation into fluorescent high-pressure mercury lamps filled with at least one of cadmium or zinc, some of the 10 prototype discharge lamps with the same specifications were compared to conventional high-pressure mercury lamps filled with only mercury. Compared to mercury lamps, the luminous flux was rapidly attenuated and the arc tube cracked due to early blackening of the wall of the arc tube during its service life. This is because cadmium or zinc oxides are generated due to the presence of oxygen (O ₂ ) or moisture in the arc tube, and these oxides adhere to the quartz, which is the material of the arc tube, and react with the quartz. It is assumed that this is due to This invention was made in view of the above circumstances, and includes applying a luminescent coating containing at least a red phosphor that emits maximum light in the wavelength range of 610 to 630 nm on the inner wall of the outer bulb, and inside the arc tube. In addition to mercury,
In metal vapor discharge lamps that contain at least one of zinc or cadmium, can be lit even with high-pressure mercury lamp ballasts, and have significantly improved color rendering properties, 0.7 x 10 ^-6 gram atoms or less per 1 c.c. The present invention provides a metal vapor discharge lamp that is sealed with halogen to reduce defects in the discharge lamp caused by a decrease in luminous flux maintenance rate and cracks in the arc tube during its life. Embodiments of the present invention will be described below. First, FIG. 5 is a structural diagram showing a metal vapor discharge lamp which is an embodiment of the present invention. In the figure, 1 indicates a shape having a cap 2 on one side. The outer tube is made of light-transmitting glass, and the inner wall of the outer tube is approximately 0.4~
Single or multiple phosphors, including at least a red phosphor that exhibits maximum luminescence in the wavelength range of 610 to 630 nm and emits linear light, deposited at a coating weight of 4 mg/cm ² The luminescent coating 4 is supported and fixed by a support frame line 5 provided in the outer tube 1, and contains at least one metal selected from zinc or cadmium in addition to mercury and a rare gas. Arc tubes 6 and 7 sealed with a prescribed amount of halogen that has the effect of increasing the vapor pressure of these metals are sealed to both ends of the arc tube 4 and are connected via the support frame line 5 or ribbon lead 8. 9 is one electrode 6 which is electrically connected to the base 2.
10 is a starting resistor, and 11 is a heat insulating film made of platinum or zirconium oxide coated on the 4 ends of the arc tube. The heat insulating film 11 is provided to control the vapor pressure of the enclosed metal, and may not be necessary depending on the shape of the arc tube or the input power. The phosphor attached to the inner wall of the outer tube 1 is a red phosphor that emits light mainly in the wavelength range of 610 to 630 [nm] and emits in a line. This is because the desired high color rendering properties can be obtained in this way, and if a phosphor that emits light in a wavelength range shorter than 610 [nm] is used, high color rendering properties cannot be obtained, and it will emit light in a wavelength range longer than 630 nm. Use of a phosphor results in a decrease in luminous efficiency and color rendering. A suitable fluorophore is yttrium vanadate activated with trivalent europium, and as shown in Figure 6, it forms a line mainly in the wavelength range of 610 to 630 nm. It is particularly suitable for the discharge lamp of the present invention. In order to improve the characteristics of this phosphor, a portion of the vanadium in its host crystal is replaced with phosphorus without significantly changing its emission spectrum.
It can be substituted with elements such as arsenic, boron, silicon, etc., and a part of yttrium can be replaced with elements such as gadolinium, zinc, cadmium, terbium, bismuth, etc., and the phosphor obtained by these substitutions also has the above-mentioned vanadium. It can be suitably used in the same way as the acid salt phosphor. Furthermore, along with the vanadate phosphor mentioned above, about 660
A mixture of magnesium fluorogermanate activated with tetravalent manganese having an emission peak wavelength around [nm] can also be suitably used in the discharge lamp of the present invention. In particular, a phosphor prepared by adhering to the inner surface of the outer tube a mixture of 50% by weight or more of a vanadate phosphor and 50% by weight or less of a magnesium fluorogermanate phosphor is preferred because it has particularly good color rendering properties. In this case, the mixing ratio of magnesium fluorogermanate phosphor is approximately 30% by weight.
It has been found that the highest color rendering properties can be obtained at around 50% by weight, and that when it exceeds 50% by weight, the luminous efficiency of the color rendering properties decreases, making it impractical. In addition, the line (line) in the wavelength range of 610 to 630 nm
When using the trivalent europium-activated vanadate phosphor described above as a red phosphor that emits light,
This phosphor can be combined with orange phosphors such as tin-activated strontium-magnesium orthophosphate phosphors, cerium and terbium or yttrium silicate phosphors activated by terbium, and cerium and terbium phosphors. Green phosphors such as activated aluminate phosphors and barium-magnesium aluminate phosphors activated with europium and manganese, europium-activated strontium chlorophosphate phosphors and europium-activated aluminium. Even when used in combination with a blue phosphor such as a barium/magnesium acid phosphor, good color rendering properties can be obtained.
In this case, the trivalent europium-activated vanadate phosphor will substantially account for about the weight of the total phosphor.
It is desirable to contain 50% by weight or more. This is 50
This is because if the amount is less than % by weight, the color rendering properties will deteriorate and the light color will appear unnatural to the human eye. Next, to explain the operation of this discharge lamp, first, the power supply voltage is applied to the ballast, and then the voltage generated by the ballast is applied between the electrodes.
A discharge occurs between the starting auxiliary electrode 9 and the starting auxiliary electrode 9, and then shifts to a main discharge between the electrodes 6 and 7. When the main discharge occurs, part or all of the enclosed zinc or/and cadmium, mercury, and halogen evaporate and emit light unique to the enclosed metal. Zinc vapor mainly has wavelengths of 328nm, 330nm, 335nm, 468nm,
It emits line spectra of wavelengths of 472nm, 481nm, and 630nm. Cadmium vapor is mainly
326nm, 340nm, 347nm, 361nm, 468nm,
It emits line spectra of wavelengths of 480nm, 509nm, and 644nm. Mercury vapor is mainly 254nm,
313nm, 365nm, 405nm, 436nm, 492nm,
It emits line spectra of wavelengths of 546nm and 578nm. Of these emitted lights, the ultraviolet emitted light is absorbed by the phosphor 3 coated on the inner wall of the outer tube 1.
It is mainly converted into linear red light having an emission peak in the wavelength range of 610 to 630 nm. On the other hand, most of the emitted light in the visible region is not absorbed by the phosphor 3 and passes through the coating of the phosphor. This passing light and the emitted light from the phosphor are mixed and finally radiated out of the discharge tube, resulting in a discharge lamp with good color rendering properties. In a metal vapor discharge lamp having such a configuration and operation, mercury (Hg) is placed inside the arc tube 4.
We tested 10 metal vapor discharge lamps each containing 60 mg of iodine, 20 torr of argon (Ar), 0.8 mg of cadmium (Cd), and various changes in iodine. The luminous flux maintenance rate and starting characteristics with respect to the lighting time were measured using the following method, and the results shown in Table 1 were obtained. Note that the luminous flux maintenance rate in Table 1 shows the average value for 10 lamps, and an x mark indicates that one or more of the 10 discharge lamps could not be lit due to a crack in the arc tube. For characteristics, those that can be lit with a high-pressure mercury lamp ballast are marked with an ○.

[Table] As can be seen from Table 1, by filling iodine, it is possible to reduce the occurrence of defects in the discharge lamp during its life, and the amount of iodine sealed can be reduced to 0.8 per c.c. of the inner volume of the arc tube. If the amount exceeded ×10 ^-6 gram atoms, it would be impossible to light the lamp using a general high-pressure mercury lamp ballast. Note that if the amount of iodine is increased to 0.7×10 ^-6 [gram atom/cc], the vapor pressure of the metal will become too high, and the characteristic blue-green line spectrum caused by metal vapor discharge of cadmium (or zinc) will become too strong. In view of this, the amount of iodine contained must be 0.7×10 ^-6 [gram atom/cc] or less. A similar tendency was also obtained when halogens other than iodine, such as bromine, were included. Specific embodiments of this invention will be described below. Example 1 The arc tube 4 is a quartz tube with an inner diameter of 9.2 [mm] and a distance between the electrodes 6 and 7 of 28 [mm], and the inside of the tube contains 16.7 [mg].
of mercury and 1.00 [mg] of zinc (Zn) plus iodine.
Enclose 0.08×10 ^-6 [g atoms/cc], 35 [torr]
After filling with argon gas, the arc tube is sealed to create an arc tube with a tube input of 100 [W]. In addition, the inner wall of the outer tube 1 is coated with 70 [wt%] trivalent europium-activated yttrium phosphovanadate phosphor and 30 [wt%]
A mixture of [wt%] tetravalent manganese-activated magnesium fluorogermanate phosphor is coated and baked to form the luminescent coating 3. and,
After the arc tube 4 was housed in the outer tube, sealed and evacuated, a 100 W metal vapor discharge lamp having the structure shown in FIG. 5 was produced. When the 10 metal vapor discharge lamps created in this way were lit using a Chiyoke type 100W high-pressure mercury lamp ballast with a rated voltage of 200V, all 10 had a discharge starting voltage (starting voltage) of 145 with almost no variation.
[V], about 130 [V] of a conventional 100W high-pressure mercury lamp.
Although it is slightly higher than that of JIS standard (JIS-C7604-1970)
It satisfied 180 [V] or less and could be lit with a high-pressure mercury lamp ballast. The average value of the 10 lights at that time was extremely high, with a color temperature of 4800 [〓], an average color rendering index of Ra94, and a luminous efficiency of 40 [lm/
W], and the tube wall load was 12.4 [W/cm ² ]. Also,
When lighting tests were conducted, no cracking of the arc tubes occurred in all discharge lamps even after 10,000 hours of lighting, and almost no blackening of the walls of the arc tubes was observed. Therefore, the luminous flux maintenance rate is the average value of 10 lights.
Even after lighting for 10,000 hours, it remained at 68.7%. For comparison, we produced 10 metal vapor discharge lamps with the same specifications as the above example, which did not contain any iodine, and conducted a lighting test. As a result, 5 of the 10 lamps were already lit after 5,000 hours of lighting.
The arc tube of the book was cracked, making it impossible to light it. In addition, after lighting at 2000 hours, the luminous flux maintenance rate was already 69% on average for 10 lamps, and there were some discharge lamps with noticeable blackening of the walls of the arc tubes. Incidentally, FIG. 7 shows the spectral distribution of the metal vapor discharge lamp of this example. The Hg and Zn symbols attached to the line spectra in the figure indicate the line spectra of mercury (Hg) and zinc (Zn) vapors, respectively. Example 2 The arc tube 4 has an inner diameter of 19.5 [mm] and electrodes 6 and 7.
The distance between the tubes is 70 [mm], and the inside of the tube is 59.0 mm.
In addition to [mg] of mercury and 7.00 [mg] of cadmium, it contains 0.1×10 ^-6 [gram atom/ml] of iodine,
After filling with 20 [torr] of argon gas, seal the arc tube to create an arc tube with a tube input of 400W. Furthermore, on the inner wall of the outer tube 1, 70 [wt%] of trivalent europium-activated yttrium phosphovanadate phosphor and 30 [wt%] of tetravalent manganese-activated magnesium fluorogermanate phosphor are mixed. The luminescent coating 3 is formed by coating and baking the coating. After the arc tube 4 was housed in the outer bulb 1, sealed and evacuated, a 400W metal vapor discharge lamp having the structure shown in FIG. 5 was produced. When the 10 metal vapor discharge lamps created in this way were lit using a Chiyoke type 400W high-pressure mercury lamp ballast with a rated voltage of 200V, the discharge starting voltage of all 10 lamps was 150 [V] with almost no variation. Although it was slightly higher than the approximately 130 [V] of a conventional 400W high-pressure mercury lamp, it met the JIS standard of 180 [V] or less, and could be lit with a high-pressure mercury lamp ballast. 10 at that time
The average value of the book is a color temperature of 4300 [〓], an average color rendering index of Ra95, which shows high color rendering properties, and a luminous efficiency of 58 [l].
m/W], and the tube wall load was 9.33 [W/cm ² ]. Furthermore, when lighting tests were conducted, no cracking of the arc tubes occurred in all discharge lamps even after 10,000 hours of lighting, and almost no blackening of the walls of the arc tubes was observed. Therefore, the luminous flux maintenance rate was 70.5% even after 10,000 hours of lighting based on the average value of 10 lights. For comparison, we produced 10 metal vapor discharge lamps with the same specifications as in Example 2 above, which did not contain any iodine, and conducted a lighting test.As a result, 4 out of the 10 lamps were already lit after 5000 hours of lighting. The arc tube was cracked and could no longer be lit. In addition, after 2,500 hours of lighting, the luminous flux maintenance rate was already 71% on average for 10 lamps, and there were some discharge lamps with noticeable blackening of the walls of the arc tubes. Incidentally, FIG. 8 shows the spectral distribution of the metal vapor discharge lamp of Example 2. The symbols Hg and Cd attached to the line spectra in the figure are mercury (Hg) and
The line spectra of each zinc (Cd) vapor are shown. Example 3 As the luminescent coating formed on the inner wall of the outer tube 1, 3
Ten 400W metal vapor discharge lamps were prepared using only the fluoropium-activated yttrium vanadate phosphor and using the same specifications as in Example 2 above, except for the other specifications. All 10 of these metal vapor discharge lamps had a discharge starting voltage of 150 [V] with almost no variation.
Can be lit with a 400W high pressure mercury lamp ballast, color temperature 410
[〓], shows high color rendering properties with average color rendering index Ra90, luminous efficiency 58.5 [lm/W], tube wall load 9.33
[W/cm ² ]. Moreover, the results of the lighting test were similar to those of Example 2 above. Example 4 The amount of mercury sealed in the arc tube 4 was set to 59.0
[mg], zinc 2.9 [mg], cadmium 1.5 [mg]
Ten 400 W metal vapor discharge lamps were prepared in the same manner as in Example 2, except that the amount of iodine was 0.2×10 ^-6 [gram atom/cc]. This metal vapor discharge lamp
All 10 lamps have a discharge starting voltage of 160 [V] with almost no variation, can be lit with a 400W high-pressure mercury lamp ballast, exhibit high color rendering properties with a color temperature of 4200 [〓] and an average color rendering index of Ra89, and emit light. Efficiency 57.5 [l
m/W], and the tube wall load was 9.33 [W/cm ² ]. Furthermore, when lighting tests were conducted, no cracking of the arc tubes occurred in all discharge lamps even after 10,000 hours of lighting, and almost no blackening of the walls of the arc tubes was observed. Therefore, the luminous flux maintenance rate was 72.3% even after 1000 hours of lighting based on the average value of 10 lights. For comparison, we produced 10 metal vapor discharge lamps with the same specifications as in Example 2 above, which did not contain any iodine, and conducted a lighting test.As a result, 4 of the 10 lamps had already been lit after 5000 hours of operation. The arc tube cracked and it became impossible to light it. Furthermore, after 2,800 hours of lighting, the luminous flux maintenance rate was already 73% on average for 10 lamps, and there were some discharge lamps with noticeable blackening of the walls of the arc tubes. Table 2 shows the lamp characteristics of the above embodiment, a conventional high-pressure mercury lamp, a fluorescent high-pressure mercury lamp, a cadmium high-pressure mercury lamp, and a zinc-containing high-pressure mercury lamp.

[Table] As is clear from Table 2, all of the metal vapor discharge lamps of the above embodiments can be lit with a high-pressure mercury lamp ballast, and in addition, conventional high-pressure mercury lamps, fluorescent high-pressure mercury lamps,
Compared to the prototype high-pressure mercury lamp containing cadmium and the high-pressure mercury lamp containing zinc, the color rendering properties are significantly improved due to the synergistic effect of the cadmium or zinc vapor discharge and the luminescent coating. In addition, when comparing the tube wall load between the spectral distribution of the cadmium-containing high-pressure mercury lamp shown in Figure 3 and the spectral distribution of Example 2 shown in Figure 8, it is found that in Example 2, the line spectrum intensity due to cadmium is kept low. Moreover, since the vapor pressure of cadmium can be increased by the sealed halogen, the tube wall load is lower than that of a conventional high-pressure mercury lamp (generally 7 to 13 [W/cm ² ), and suppresses the generation of cadmium or zinc oxides due to the action of the ^encapsulated halogen, resulting in luminescence. The durability of the tube 4 increases,
As a result, a discharge lamp with a long life and a low defect rate can be obtained. For example, the lifespan of the metal vapor discharge lamp of Example 2 was 12,000 hours on average for 10 prototypes, which was equivalent to the approximately 12,000 hours of a conventional high-pressure mercury lamp. As stated above, this invention
A luminescent coating containing at least a red phosphor that emits maximum light in the wavelength range of The synergistic effect of the luminescence spectrum produced by the vapor discharge of at least one metal, zinc or cadmium, and the luminescence produced by the phosphor significantly improves color rendering, and it is said that it can be lit using a high-pressure mercury lamp ballast. This method is effective, and because the action of the sealed halogen can suppress the decrease in luminous flux maintenance factor and cracking of the arc tube during its life, there is also the effect that a metal vapor discharge lamp with fewer defects can be obtained. Note that, considering the main purpose of the present invention, it is clear that similar effects can be obtained in a so-called electrodeless discharge lamp in which the enclosed metal vapor is excited with high frequency and emitted light without providing an electrode in the arc tube.

[Brief explanation of the drawing]

Figures 1, 2, and 3 are diagrams showing the spectral distribution of a high-pressure mercury lamp, a fluorescent high-pressure mercury lamp, and a cadmium-containing high-pressure mercury lamp, respectively. Figure 4 shows the relationship between the amount of cadmium enclosed and the 546 nm line spectrum intensity due to mercury. FIG. 5 is a structural diagram of a discharge lamp shown as an example of the present invention; FIG. 6 is a diagram showing the emission spectrum of a red phosphor; FIG. 8 and 8 are diagrams showing spectral distributions of discharge lamps of Examples 1 and 2 of the present invention. In the figure, 1 is an outer tube and 4 is an arc tube.

Claims (1)

[Scope of Claims] 1. An outer tube whose inner wall is coated with a luminescent coating containing at least a red phosphor that emits maximum light in a wavelength range of 610 to 630 nm and emits linear light; In addition to mercury as the main luminescent component, at least one of zinc or cadmium is sealed inside, and 0.7 x per c.c.
A metal vapor discharge lamp with an arc tube containing less than 10 ^-6 gram atoms of halogen. 2. The metal vapor emitting device according to claim 1, wherein the luminescent coating contains 50% by weight or more of a red phosphor, and the remainder is a tetravalent manganese-activated magnesium fluorogermanate phosphor. electric light. 3. The metal vapor discharge lamp according to claim 1 or 2, wherein the red phosphor is yttrium vanadate activated with trivalent europium. 4 The red phosphor is a yttrium vanadate activated with trivalent europium, and the vanadate phosphor has a base crystal in which part of the vanadium element is phosphorus, arsenic, boron, or silicon, and Claim 1, 2, or 3, wherein a part of the yttrium element is substituted with at least one element selected from each of gadolinium, zinc, cadmium, terbium, and bismuth. metal vapor discharge lamp.