JPS6338830B2 - - Google Patents

Description

[Detailed description of the invention]

This invention relates to a novel 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 features 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 general spectral distribution of this high-pressure mercury lamp), and its use is actually 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 in order to have high efficiency, long life, and improve color rendering properties. Ivy. 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. (The general spectral distribution of this fluorescent high-pressure mercury lamp is shown in Figure 2.) While color rendering is improved by using a phosphor in this way, in a high-pressure mercury lamp, metals other than mercury, such as metals other than mercury, are used inside the arc tube. Attempts have been made in the past to add an emission spectrum due to the vapor discharge of these metals to the emission spectrum due to the mercury vapor discharge by encapsulating cadmium or zinc to improve color rendering properties. 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 lamps 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 tube wall load was 50
% or more, resulting in approximately 1000
A problem occurred in which the arc tube broke after being lit for a certain period of time. On the other hand, as a method for improving color rendering properties, there is a so-called metal halide lamp 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 come to be able to obtain good color rendering properties, it is not possible to use alkaline earth metal oxide electrodes with good vapor emission, and because the halide is sealed in the arc tube, impure 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. This invention was made in view of the above points, 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,
At least one of zinc or cadmium is sealed in the arc tube, and the color rendering properties are significantly improved by the synergistic effect of the emission spectrum caused by the vapor discharge of at least one metal of zinc or cadmium and the light emission by the phosphor, and To provide a metal vapor discharge lamp that can be lit even with a ballast for a high-pressure mercury lamp. An embodiment of the present invention will be described below. First, Fig. 4 is a structural diagram showing a metal vapor discharge lamp which is an embodiment of the present invention. An outer tube made of light-transmitting glass, 3 is about 0.4 to 4 on the inner wall of this outer tube.
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 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. The sealed arc tube 6 and 7 are sealed to both ends of the arc tube 4, and electrodes 9 are electrically connected to the cap 2 via the support frame 5 or the ribbon lead 8. A starting auxiliary electrode is sealed near one of the electrodes 6, 10 is a starting resistor, and 11 is a heat insulating film made of platinum or zirconium oxide or the like coated on the end of the arc tube 4. 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 phosphor is yttrium vanadate activated with trivalent europium, and as shown in FIG. 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 the host crystal can be replaced with elements such as phosphorus, arsenic, boron, and silicon without significantly changing its emission spectrum, and a portion of the yttrium can be replaced with gadolinium, zinc, etc. , cadmium, terbium, bismuth, etc., and phosphors obtained by these substitutions can also be suitably used in the same way as the vanadate phosphors described above. 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 color rendering properties and luminous efficiency decrease, making it impractical. In addition, the line (line) in the wavelength range of 610 to 630 nm
When using the above trivalent europium-activated vanadate phosphor as a red phosphor that emits light, this phosphor can be used as an orange phosphor such as a tin-activated strontium/magnesium orthophosphate phosphor. , yttrium silicate phosphors activated with cerium and terbium or terbium and aluminate phosphors activated with cerium and terbium and barium aluminate activated with europium and manganese.・Good color rendering even when mixed with green phosphors such as magnesium phosphors, blue phosphors such as europium-activated strontium chlorophosphate phosphors, europium-activated barium/magnesium aluminate phosphors, etc. You can get sex.
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, a power supply voltage is applied to the ballast, and then, when the voltage generated by the ballast is applied to the arc tube, the electrodes 6
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 and mercury evaporate and emit light unique to enclosed metals. Zinc vapor is mainly 328n
m, 330nm, 335nm, 468nm, 472nm, 481nm,
It emits a line spectrum of each wavelength of 636nm.
Cadmium vapor mainly has wavelengths of 326nm, 340nm,
347nm, 361nm, 468nm, 480nm, 509nm,
It emits a line spectrum of each wavelength of 644nm.
Mercury vapor mainly has wavelengths of 254nm, 313nm, 365nm,
It emits line spectra of wavelengths of 405nm, 436nm, 492nm, 546nm, and 578nm. Of these radiated lights, the ultraviolet rays are absorbed by the phosphor 3 coated on the inner wall of the outer tube 1 and converted into line-shaped red light having an emission peak in the wavelength range of 610 to 630 nm. Ru. 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. Specific embodiments of this invention will be described below. Example 1 The arc tube 4 was a quartz tube with an inner diameter of 9.2 [mm] and a distance between the electrodes 6 and 7 of 31 [mm], and 15.5 [mg] of mercury and 2.2 [mg] of cadmium (Cd) were sealed inside the tube. have, 35
After filling with [torr] of argon gas, the arc tube is sealed to create an arc tube with a tube input of 100 [W]. Furthermore, the inner wall of the outer tube 1 is coated with 70 [wt%] trivalent europium-activated yttrium phosphovanadate phosphor and 30 [wt%] tetravalent manganese-activated magnesium fluorogermanate phosphor. The mixture is applied and baked to form a luminescent coating 3. After the arc tube 4 was housed in the outer tube, sealed and evacuated, a 100 W metal vapor discharge having the structure shown in FIG. 4 was created. When the metal vapor discharge lamp created in this way was lit with a Chiyoke type 100W high-pressure mercury lamp ballast with a rated voltage of 200V, the discharge starting voltage (starting voltage) was 100V.
[V], much lower than the approximately 130 [V] of conventional 100W high-pressure mercury lamps, and could be lit with a ballast for high-pressure mercury lamps. At that time, it exhibited very high color rendering properties with a color temperature of 4800 [〓] and an average color rendering index of Ra94, a luminous efficiency of 37 [lm/W], and a tube wall load of 11.2 [W/cm ² ]. Example 2 The arc tube 4 was a quartz tube with an inner diameter of 9.2 [mm] and a distance between the electrodes 6 and 7 of 28 [mm], and 16.7 [mg] of mercury and 1.41 [mg] of zinc (Zn) were sealed inside the tube. have, 35
A 100 W metal vapor discharge lamp was prepared in the same manner as in Example 1, except that the arc tube was sealed after filling with [torr] of argon gas to produce an arc tube with a tube input of 100 [W]. The discharge starting voltage of this metal vapor discharge lamp is 102 [V], it can be lit with a 100W high-pressure mercury lamp ballast, the color temperature is 4700 [〓], and the average color rendering index
Shows high color rendering properties of Ra80 and luminous efficiency of 35 [lm/
W], and the tube wall load was 12.4 [W/cm ² ]. Incidentally, FIG. 6 shows the spectral distribution of this metal vapor discharge lamp. attached to the line spectrum in the figure.
The symbols Hg and Zn indicate the line spectra of mercury (Hg) and zinc (Zn) vapors, respectively. Example 3 The arc tube 4 was a quartz tube with an inner diameter of 19.5 [mm] and a distance between the electrodes 6 and 7 of 70 [mm], and 59.2 [mg] of mercury and 0.845 [mg] of cadmium were sealed inside the tube. 20
After filling with [TORR] argon gas, seal the arc tube to create an arc tube with a tube input of 400W. Also,
The inner wall of the outer tube 1 is coated with 70 [wt%] trivalent europium-activated yttrium phosphovanadate phosphor and 30
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 bulb 1, sealed and evacuated, a 400 W metal vapor discharge lamp having the structure shown in FIG. 4 was produced. When the fluorescent vapor discharge lamp prepared in this way was lit with a 400W high-pressure mercury lamp ballast with a rated voltage of 200V, the discharge starting voltage was 98 [V].
It was even lower than the approximately 130 [V] of a conventional 400W high-pressure mercury lamp, and could be lit using a high-pressure mercury lamp ballast. At that time, color temperature 4100 [〓], average color rendering index
Shows high color rendering properties of Ra86 and luminous efficiency of 56 [lm/
W], and the tube wall load was 9.33 [W/cm ² ]. Example 4 The amount of mercury sealed in the arc tube 4 was 59.0 [mg]
A 400W metal vapor discharge lamp was prepared in the same manner as in Example 3 above, except that the amount of cadmium was changed to 7.9 [mg]. The discharge starting voltage of this metal vapor discharge lamp is 100
[V], can be lit with a 400W high-pressure mercury discharge lamp ballast, color temperature 4300 [〓], average color rendering index Ra95
It exhibited high color rendering properties, luminous efficiency of 56 [lm/W], and tube wall load of 9.33 [W/cm ² ]. Incidentally, FIG. 7 shows the spectral distribution of this metal vapor discharge lamp. attached to the line spectrum in the figure.
The symbols Hg and Cd indicate the line spectra of mercury (Hg) and cadmium (Cd) vapors, respectively. Example 5 The arc tube 4 was a quartz tube with an inner diameter of 19.5 [mm] and a distance between the electrodes 6 and 7 of 55 [mm], and 75.1 [mg] of mercury and 6.33 [mg] of zinc were sealed inside the tube. Embodiment 3 is the same as above except that after filling 20 [torr] of argon gas, the arc tube is sealed to create an arc tube with a tube input of 400 [W].
A 400W metal vapor discharge lamp was created in the same manner.
The discharge starting voltage of this metal vapor discharge lamp is 95 [V], it can be lit with a ballast for a 400W high-pressure mercury lamp, it exhibits high color rendering properties with a color temperature of 4400 [〓], an average color rendering index of Ra71, and a luminous efficiency of 55 [〓]. lm/W], pipe wall load 11.9
[W/cm ² ]. Example 6 As the luminescent coating formed on the inner wall of the outer tube 1, 3
A 400W metal vapor discharge lamp was prepared using only the valent europium-activated yttrium vanadate phosphor and using the same specifications as in Example 3 above, except for the other specifications. The discharge starting voltage of this metal vapor discharge lamp is 98 [V],
Can be lit with a 400W high-pressure mercury lamp ballast, and the color temperature
4000 [〓], average color rendering index Ra84, high color rendering properties, luminous efficiency 57 [lm/W], tube wall load 93.3
[W/cm ² ]. Example 7 The amount of mercury sealed in the arc tube 4 was 59.2 [mg].
A 400 W metal vapor discharge lamp was produced in the same manner as in Example 3 above, except that zinc was used at 3.1 [mg] and cadmium was used at 1.52 [mg]. This metal vapor discharge lamp has a discharge starting voltage of 99 [V], can be lit with a 400W high-pressure mercury lamp ballast, has a color temperature of 4200 [〓], and has an average color rendering index.
Shows high color rendering properties of Ra88 and luminous efficiency of 56 [lm/
W], and the tube wall load was 9.33 [W/cm ² ]. The above embodiments and conventional high-pressure mercury lamps, fluorescent high-pressure mercury lamps, and prototype high-pressure mercury lamps containing cadmium,
Table 1 shows the lamp characteristics of the zinc-containing high-pressure mercury lamp.

[Table] As is clear from Table 1, all of the metal vapor discharge lamps of the above examples can be lit with a high-pressure mercury lamp ballast, and can be used with conventional high-pressure mercury lamps, fluorescent high-pressure mercury lamps, and the prototype cadmium-containing ballast. The color rendering properties are significantly improved compared to high-pressure mercury lamps and high-pressure mercury lamps containing zinc. It is presumed that the remarkable improvement in color rendering properties of the metal vapor discharge lamps of the above examples is due to the following reasons. That is, by sealing cadmium or zinc inside the arc tube 4, the emission spectrum due to vapor discharge of cadmium or zinc causes
The emitted light mainly in the blue-green part is supplemented, and the emitted light in the red part is mainly supplemented by the light emission of the luminescent coating, and the color rendering properties are improved. A luminescent coating for the 546nm emission spectrum caused by mercury vapor discharge, which contributes to improved color rendering not only based on the sum of these emitted lights but also due to the synergistic effect of cadmium or zinc vapor discharge and the luminescent coating. The color rendering properties are further improved by increasing the ratio of the emission spectrum at 619 nm. This can be confirmed by the relationship between the ratio of the line spectrum intensity of 619nm to the line spectrum intensity of 546nm depending on the amount of cadmium contained in a test using a 400W discharge lamp, as shown in Figure 8. It was confirmed that the strength ratio was increased by sealing. In other words, it is emitted from the phosphor like this
The fact that the radiation output of the 619 nm line spectrum itself increases when cadmium or zinc is sealed means that the output of ultraviolet radiation from these metal vapor discharges and the relationship between its wavelength and the excitation spectrum of the phosphor are improved. This is thought to be due to this. Furthermore, when comparing the spectral distribution of the cadmium-containing high-pressure mercury lamp shown in Fig. 3 with the spectral distribution of Example 4 shown in Fig. 7, it is found that the spectral distribution of Example 4 can suppress the line spectrum intensity due to cadmium to a low level. In all of the above examples, the wall load is the same as that of a conventional high-pressure mercury lamp (generally 7 to 13 [W/cm ² ]).
within the range of ), about the same as 9 to 12.5 [W/
cm ² ], and as a result, the durability of the arc tube 4 is increased, resulting in a metal vapor discharge lamp with a long life. As described above, in this invention, a luminescent coating containing at least a red phosphor that emits maximum light in the wavelength range of 610 to 630 nm is applied to the inner wall of the outer tube, and contains zinc or cadmium in addition to mercury. Since at least one of the metals zinc or cadmium is sealed in the arc tube, color rendering properties are significantly improved due to the synergistic effect of the emission spectrum caused by the vapor discharge of at least one of the metals, zinc or cadmium, and the light emission from the phosphor. It has the advantage of being able to be lit using a mercury lamp ballast. Note that, considering the main purpose of this 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, and Figure 4 is a structural diagram of a discharge lamp shown as an example of the present invention. Fig. 5 shows the emission spectrum of the red phosphor, Figs. 6 and 7 show the spectral distribution of the discharge lamps of Examples 2 and 4 of the present invention, and Fig. 8 shows the cadmium content and the spectral distribution. FIG. 3 is a diagram showing the relationship between the ratio of the spectral intensity of a phosphor to the mercury line spectral intensity. In the figure, 1 is an outer tube and 4 is an arc tube.

Claims (1)

[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 the wavelength range of 610 to 630 nm and emits linear light; , a metal vapor discharge lamp equipped with an arc tube in which, in addition to mercury, at least one of zinc or cadmium is sealed as the main luminescent component. 2. The metal vapor according to claim 1, characterized in that the luminescent coating contains 50% by weight or more of a red phosphor, with the remainder being a tetravalent manganese-activated magnesium fluorogermanate phosphor. discharge lamp. 3. The metal vapor discharge lamp according to claim 1 or 2, wherein the red phosphor is yttrium vanadate activated with trivalent europium. However, as the vanadate phosphor, a part of the elements in the host crystal can be replaced with at least one element selected from phosphorus, arsenic, boron, silicon, gadolinium, zinc, cadmium, terbium, and bismuth. shall be.