JPS6213791B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a high-pressure metal vapor discharge device in which buffering metals such as sodium and mercury and starting aid gas are sealed in a light-transmitting arc tube, and in particular a novel discharge device with a high color temperature and excellent color rendering properties and efficiency. It provides equipment. Regarding a high-pressure sodium discharge lamp, when the inner diameter of the arc tube is dmm, the average potential gradient of the tube E (V/cm)
It is already known that high-pressure metal vapor discharge lamps operated in the range of E37.7−2.05d (where E is the lamp voltage divided by the distance between the electrodes of the arc tube) exhibit excellent color rendering. ing. However, considering practical issues such as efficiency and lamp voltage, it is difficult to increase the color temperature of such discharge lamps.
It was almost impossible to put anything higher than 2500K into practical use. In other words, it was possible to experimentally obtain a discharge lamp with a color temperature of 2500 to 3500K by increasing the sodium vapor pressure inside the tube or increasing the load on the tube wall, but in this case the efficiency was greatly reduced; In addition, there were drawbacks such as the lamp voltage becoming too high. An object of the present invention is to eliminate the above-mentioned drawbacks and to realize a discharge device with high color rendering properties and high efficiency while keeping the lamp voltage at a low value even when the color temperature is about 2500K or higher. The present inventors have been working on the problem of improving the color rendering properties of high-pressure sodium discharge lamps for many years, but the final problem remained unsolved: the above-mentioned low color temperature. In other words, light sources with a color temperature of approximately 2,500K or less have limited uses for general indoor lighting, and from an application standpoint, there has been a demand for light sources with a color temperature at least close to that of incandescent light bulbs or halogen light bulbs. Accordingly, the present inventors once again conducted detailed studies including computer simulation experiments regarding the optimization of the color rendering properties of high-pressure sodium discharge lamps. As a result, the arc tube is discharged in a range where the average potential gradient E (V/cm) of the arc tube is E37.7-2.05d, and the visible radiation power from the arc tube is mainly red in wavelengths longer than 620 nm. It has been found that by suppressing the radiation power, the above drawbacks can be eliminated and a discharge device with high color temperature, high color rendering properties, high efficiency and low lamp voltage can be realized. Hereinafter, the present invention will be explained in detail based on Examples. As shown in FIG. 1, the outline of the arc tube 1 of the discharge device used in the experiment is as follows.
It consists of a sealing ceramic end cap 3 provided at both ends of the cap, a niobium tube 4 for introducing an electrode through the cap 3, and an electrode 5 provided at the tip inside the niobium tube 4. Additive 6 consisting of sodium as a luminescent substance and one or more of mercury and cadmium as a buffer gas
is added, and one or more of xenon, argon, and neon is further enclosed as a rare gas for starting aid. In particular, in experiments related to the present invention, tube inner diameters d were 6.3, 7.6, 9.7, 10.8,
Alumina tubes of 11.5 and 13.5 mm were used, the distance between both electrodes was set to 25 to 82 mm, corresponding to the rated lamp input, and 3 to 15 mg of sodium, 3 to 60 mg of mercury, or 10 to 80 mg of cadmium were added. Furthermore, as rare gases, approximately 20 Torr of main xenon and neon/argon Benning gas (Ne + 0.1 to 1.0% Ar) was sealed. The inventors of the present invention have concluded that the basic concept of the reexamination is that improvements in the so-called arc tube design based on changes in parameters such as arc tube dimensions, vapor pressure inside the tube, lamp voltage, and lamp current alone do not meet the objectives of the present invention. Considering that it would be difficult to realize a discharge device that does this, we searched for other methods. The final conclusion regarding this method was to cut out the radiation power in a specific wavelength range out of the luminous radiation power emitted from the arc tube. Therefore, as a first step, we conducted a simulation experiment using a computer to examine the emission characteristics when the emission power in a specific wavelength range was cut out from the emission power distribution from a high-pressure sodium discharge. It has become clear that a discharge device with a similar shape can be realized. Here, the content of the simulation experiment using an electronic computer will be explained. For the experimental lamp, the radiation power intensity for each wavelength is determined by spectrometry. 380nm～
Various calculated radiation power distributions are obtained by multiplying the radiation power intensity by an arbitrary constant corresponding to the cutoff wavelength over the wavelength range of 780 nm, varying for all wavelengths or for each wavelength. If the average color rendering index Ra, color temperature Tc, and lamp efficiency (decrease Δη) are determined from these calculated radiation power distributions, various calculated lamp characteristics can be obtained. These calculations were performed using an electronic computer. (1) An effective method is to cut the red radiation power in the long wavelength range. In other words, as shown in Figure 2, when all visible radiation power in the wavelength range longer than a certain cutoff wavelength λc is virtually cut off, (i) as shown by curves a and a' in Figure 2, , the color temperature Tc is, for example, 4000 ~ at λc = 620nm.
It increases to 6000-7000K at 5000K and λc=600nm. (ii) As shown by curves b and b' in FIG. 2, the reduction Δη of the lamp efficiency due to the cut of the red radiation power is small because the relative luminous efficiency of the red radiation power is low. For example, λc=
At 620nm, even if Tc increases to a maximum value of 5000K, the efficiency decrease Δη is only about 18%.
It's nothing more than that. Here, the decrease in efficiency Δη is defined by the following equation. Δη = [(η - η′) / η] × 100 (%) η: Efficiency of a lamp that does not cut red radiation power η′: Efficiency of a lamp that cuts red radiation power (iii) Furthermore, there are characteristics regarding color rendering properties. The facts have become clear. In other words, if the radiation power in the long wavelength range is cut with respect to existing light sources, it is inevitable that the color rendering will be greatly reduced.
In the discharge device according to the present invention, the curve c in FIG.
and c′, the average color rendering index Ra
A value of about 60 to 90 can be achieved if λc is 620 nm or more. The data in FIG. 2 are for the discharge state at color temperatures of approximately 2500K and 2800K when curves a, b, c and curves a', b', and c' do not cut off the red radiation power, respectively. Also,
The discharge lamp used to collect this data had a tube inner diameter d of 11.5 mm and a distance between both electrodes of 52 mm.
It contains 8.6 mg of Na, 32 mg of Hg, and 20 Torr of Xe, and lights up with an input of 400 to 450 W. (2) A more detailed investigation of the phenomenon described in item (1) (iii) above revealed that it is a phenomenon unique to high-pressure sodium discharge. That is, in a high-pressure sodium discharge, for example, as the sodium vapor pressure increases, the radiation power from the arc tube increases over the entire visible range, and in particular, the red radiation power increases significantly. Finally, in the vapor pressure region corresponding to a color temperature of approximately 2300 to 2400K or higher, the red radiation power becomes rather excessive compared to an incandescent lamp, and the fluttering effect on red becomes excessive, resulting in an average color rendering index. Ra will actually start to decline.
Therefore, cutting off such excessive red radiation power has a favorable result in increasing Ra. In Figure 2, λc is
This is why Ra increases as the radiation power cut width is widened from 700 nm to 630 nm. From these results, it is necessary to maintain the discharge state of the arc tube in a range where the red radiation power is excessive in order to increase both the color temperature and color rendering properties in the discharge device that is the object of the present invention. . As revealed in Japanese Patent Publication No. 50-39944, this range corresponds to the area where the color satisfaction is 1.0 or more, and it is determined by the average potential gradient E of the tube.
It can be specified under the condition that (V/cm) is E37.7−2.05d. (3) When λc reaches a wavelength range shorter than 620 nm, the color temperature increases significantly, but as shown in Figure 2, the average color rendering evaluation Ra decreases significantly, and on the other hand, the emitted color also changes from the blackbody radiation locus. This is not preferable because it largely shifts to the green area. Therefore,
In the discharge device targeted by the present invention, λc is 620 nm.
It is preferable to have a long wavelength value of 620 nm or more, that is, to cut red radiation power in the long wavelength range of 620 nm. (4) As shown in Figure 3, the lamp voltage when the radiation power in the long wavelength region is not cut rises rapidly as the color temperature rises. For example, the lamp voltage is about 120V at a color temperature of 2550K, but increases to about 170V at a color temperature of 3000K, making such a discharge device impractical as the lighting ballast is large and expensive. On the other hand, lamp efficiency (=
The total luminous flux/lamp input) is also as shown in Figure 4.
It decreases rapidly with color temperature, about 75 at 2550K.
m/W, whereas at 3000K it is approximately 50
m/W. On the other hand, in order to realize a color temperature of 3000K in the discharge device according to the present invention, it is sufficient to cut out the radiation power in the long wavelength region of about 640nm or more from the emission power distribution originally corresponding to the color temperature of 2500K. The lamp voltage at that time is
The voltage remains at 120V, and the lamp efficiency is approximately 6%.
A value of about 70 m/W is obtained. The discharge lamp used to obtain the data in FIGS. 3 and 4 has exactly the same arc tube dimensions and lighting conditions as the discharge lamp used to obtain the data in FIG. From the above results, the average potential gradient E of the arc tube
(V/cm) is E37.7-2.05d, and by cutting out the red radiation power in the long wavelength range of 620 nm or more from the visible radiation power from the arc tube, a high color temperature can be achieved. It has become clear that an excellent new light source with high color rendering properties, high efficiency, and low lamp voltage can be realized. Next, the present inventors confirmed the results of the above simulation experiment using an actual prototype discharge device. A typical example is described below. Example 1 Color temperature approximately 3000K based on the principle of the present invention
We prototyped 150W and 400W discharge lamps. The arc tube specifications are shown in Table 1, and the discharge lamps are shown in Table 5. In this case, in order to implement the above principle, the arc tube 1 shown in Table 1 is placed inside an outer tube 7 made of phosphoric acid-based heat ray absorbing glass that exhibits light transmission characteristics as shown in FIG. I have kept it. For comparison,
Ordinary hard glass (molybdenum glass) with almost flat light transmittance over the entire visible range as the outer tube.
We also prototyped a discharge lamp with conventional specifications using . Table 1 summarizes the various characteristics of the prototype discharge lamp at the rated input and compares it with a conventional specification lamp with the same color temperature. The results shown in Table 1 will be explained using a 150W discharge lamp as an example. As shown in the table,
Conventional discharge lamps have a color temperature of 3000K (measured value is
2990K), the lamp efficiency is 38m/
At W, the lamp voltage is 142V. For this reason, an expensive stabilizer with a secondary voltage of around 280V, which is higher than the primary voltage (200V), is required. On the other hand, according to the discharge lamp of the present invention, when using an arc tube with the same specifications as a conventional discharge lamp and setting the color temperature to 3000K (measured value 3010K) even with the same lamp input, the lamp efficiency is 53m/ The lamp voltage is 139.5% higher than that of conventional discharge lamps, and the lamp voltage is low at 103V, so it can be lit with an inexpensive single-choke type ballast whose secondary voltage is the same as the primary voltage. Moreover, the radiation power distribution is shown in FIG. In the figure, curve a shows the discharge lamp of the present invention, and curve b shows the conventional discharge lamp, both of which are 400W discharge lamps. These discharge lamps have a color temperature of about 3000K, which is similar to halogen bulbs, but their efficiency is about 3 to 4 times that of halogen bulbs, making them ideal for the coming energy-saving era. It can be said to be a light source. Example 2 Arc tube 1 with the same specifications as the 150W discharge lamp of Example 1
Furthermore, as shown in Figure 8, the visible range of blue ~
A shield as shown in Figure 9 is obtained by providing a dielectric film 8 (a reflective surface made of multi-layered vapor deposited MgF, ZnS, etc., called a cold mirror) on the back glass 9, which reflects green light well and absorbs red light. A prototype beam-type discharge lamp was manufactured. The characteristics of this lamp are also summarized in Table 1. After all, the light color is comparable to that of a sealed beam bulb, but even with a 150W bulb, the illuminance is comparable to a 500W sealed beam bulb. Example 3 A discharge lamp 10 with conventional specifications in which an arc tube with the same specifications as the 150W discharge lamp of Example 1 was held in an outer bulb made of ordinary hard glass was replaced with heat ray absorbing glass having the light transmission characteristics shown in FIG. A prototype discharge device was manufactured as shown in FIG. 10, which was combined with a metal lamp having a plate 11 on the bottom surface. Its properties are also shown in Table 1.
The light color of this discharge device is almost comparable to that of a halogen bulb, but the illuminance obtained with an input of 150W is comparable to that of a 500W halogen bulb. The feature of this discharge device is that, compared to the two embodiments described above, it is not necessary to cut off the red radiation power in the discharge lamp itself, so it is easy to prototype the discharge lamp.

[Table] From the above simulation experiments and measurements of various characteristics of the actually prototyped discharge device, it was found that the average potential gradient of the arc tube was E37.7−2.05d (V/cm), and
It has become clear that by suppressing the red radiation power in the long wavelength region of 620 nm or more, it is possible to realize a discharge device with high color temperature, high color rendering properties, high efficiency, and low lamp voltage. The high-pressure metal vapor discharge device based on the present invention can be expected to become one of the mainstream high-intensity lamps for indoor lighting as an energy-saving lamp.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway cross-sectional view showing a discharge heat twisted arc tube according to the present invention, and Fig. 2 shows a discharge device in which red radiation power in the long wavelength range is cut out of the visible radiation power from a high-pressure sodium discharge. Characteristic diagrams of color temperature, efficiency, and average color rendering index; Figures 3 and 4 are diagrams of the relationship between color temperature and lamp voltage, and color temperature and efficiency, respectively, of a conventional high-pressure sodium discharge lamp; Figure 5 is a diagram of the relationship between color temperature and efficiency of the present invention. FIG. 6 is a side view of a discharge device that is an example. FIG. 6 is a light transmission characteristic diagram of the glass used for the outer bulb of the discharge lamp. FIG. 7 is a radiation power distribution diagram at the rated input of the discharge lamp. The figure shows the light reflectance of a dielectric film used to suppress the red radiation power of a sealed beam discharge lamp which is another embodiment of the present invention. FIG. 10 is a sectional view of a discharge device according to another embodiment of the present invention. 1... Arc tube, 5... Electrode, 7... Outer tube, 8...
...Dielectric film, 11... Heat ray absorbing glass plate.

Claims (1)

[Claims] 1 Equipped with an arc tube with electrodes on both ends and filled with sodium, buffer gas, and starting gas,
When the inner diameter of the arc tube is d (mm), the average potential gradient E (V/cm) of this arc tube is E37.7-
2.05d, and is further provided to surround at least a portion of the arc tube, and includes means for suppressing red radiation power in a long wavelength range of 620 nm or more out of the visible radiation power from the arc tube. A high-pressure metal vapor discharge device comprising: