JP4411749B2 - Metal vapor discharge lamp - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a metal vapor discharge lamp used as an ultraviolet curing lamp, for example.
[0002]
[Prior art]
Conventionally, high-pressure mercury lamps and iron-containing metal vapor discharge lamps have been used as ultraviolet curing lamps.
[0003]
An iron-containing metal vapor discharge lamp is one in which iron is enclosed as a luminescent metal in a luminous tube and iodine is enclosed as a halogen, but various types of sensitizers can be adapted to their spectral sensitivity curves. A small amount of metal is added. For example, adding Sn as an additive metal is described in US Pat. No. 3,590,307, and adding Pb is described in JP-A-55-133743.
[0004]
The lamp filled with iron iodide has enhanced light emission of 350 to 450 nm as compared with a high-pressure mercury lamp, and is preferred to be used over a high-pressure mercury lamp depending on the sensitizer.
However, as diversification of sensitizers has progressed, the demands on the spectral distribution of the lamps have also diversified, and there has been a desire to enhance other wavelength ranges in addition to 350 to 450 nm in iron-containing metal vapor discharge lamps. For example, enhancement of 450 to 500 nm.
[0005]
In recent years, as the demand for increasing the UV intensity has increased, this has been addressed by increasing the lamp input value per emission length, but when the iron-containing metal vapor discharge lamp is lit for a long time at a high load, There is a problem that a thin film containing iron is formed inside the quartz tube forming the arc tube, and the generated light is blocked by the film and the luminous intensity of the lamp is significantly reduced.
[0006]
Therefore, as measures against this, a method of adding a trace amount of metal and a method of using bromine as a halogen (for example, see Japanese Patent Laid-Open No. 5-135740) are considered.
[0007]
[Problems to be solved by the invention]
However, it has been found that encapsulating bromine as a halogen causes a problem with the startability of the lamp. This is presumably because bromine contained in the lamp cannot completely return to the form of metal bromide or mercury bromide after the lamp is extinguished, and partly exists as bromine gas (Br ₂ ). That is, in the case of iodine which has been mainly used as a halogen conventionally, I ₂ is solid at room temperature (25 ° C.) even if it remains I ₂ without returning to the form of metal iodide or mercury iodide. On the other hand, Br ₂ has a high vapor pressure, and it is considered that the negative bromine gas fills the inside of the arc tube at the start of the lamp, which causes the startability to be difficult.
[0008]
In view of the above, an object of the present invention is to increase the emission intensity of 450 to 500 nm without reducing the starting performance in a metal vapor discharge lamp in which iron as a main light emitting metal element and iodine as a halogen are enclosed. .
[0009]
[Means for Solving the Problems]
In the metal vapor discharge lamp of the present invention, mercury as a buffer gas, iron as a luminescent metal, iodine and bromine as halogens, and a rare gas for starting are enclosed in an arc tube, and encapsulated atoms converted per arc tube volume In terms of numbers, when iodine is represented by (I) and bromine by (Br), (Br) + (I) is 2 × 10 ^{−7 to} 14 × 10 ⁻⁷ (mol / cc), and (Br) : The atomic ratio represented by (I) is in the range of 10:90 to 30:70.
[0010]
The inventors of the present application have found that the above-mentioned problems can be solved by replacing the specific ratio of iodine conventionally used as encapsulated halogen with bromine, and have reached the present invention. That is, by replacing an amount in the range of 10 to 30% of the total number of atoms of encapsulated iodine with bromine atoms, the emission energy of 350 to 400 nm and 400 to 450 nm is about 20 to 30%, particularly the emission intensity of 450 to 500 nm. It increases about 40-70%. When the replacement rate is less than 10%, the strength increase is not sufficient, and when the replacement rate exceeds 30%, the starting performance of the lamp is significantly deteriorated. This is presumably because the vapor pressure of bromine gas in the arc tube at the start of the lamp was increased due to the increased bromine sealing ratio.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be further described together with embodiments.
[0012]
FIG. 1 is a diagram showing the structure of a metal vapor discharge lamp according to an embodiment of the present invention. The metal vapor discharge lamp of the present embodiment has a structure in which electrodes 2 are provided at both ends in the arc tube 1, and a molybdenum foil 3 and a base 4 are provided in the narrow diameter portion of the arc tube 1. Quartz can be used as the material of the arc tube.
[0013]
Inside the arc tube, mercury for a buffer gas, iron as a main luminescent metal, iodine and bromine as halogens are sealed, and a rare gas for starting is further sealed.
[0014]
Halogen can be enclosed in the arc tube in the form of halides such as FeI ₂ , FeBr ₂ , HgI ₂ , HgBr _2, etc., and mercury and iron can be enclosed as halides or simple metals, and these are appropriately combined to give a predetermined Enclosed so as to have a quantity and ratio.
[0015]
As the rare gas, He, Ne, Xe, Ar, Kr, or the like can be used. However, in the case of a discharge lamp in which the luminous intensity gradually increases after lighting, Ar is preferable from the viewpoint of price.
[0016]
In addition, when the spectral characteristics are improved, an additive metal for spectral improvement (for example, Mg, Bi, Ta, Cd, Mn, Sn, Pb, etc.) is enclosed in the arc tube. Regarding the converted number of encapsulated atoms, when the iron is represented by (Fe) and the spectrally improved metal is represented by (M), the encapsulated ratio represented by (M) / (Fe) is preferably 0.3 or less. . This is to effectively maintain the main light emission of iron, which is particularly excellent in luminous efficiency.
[0017]
In particular, when the above additive metal is used, it is preferable to use at least one kind of lead or tin, and it is practical to use either one of them.
[0018]
With respect to iodine and bromine, with respect to the number of encapsulated atoms converted per arc tube inner volume, when iodine is represented by (I) and bromine is represented by (Br), (Br) + (I) is 2 × 10 ^{−7 to} 14 × 10 ^{− 7} (mol / cc), and the ratio of the inclusions is appropriately adjusted so that the atomic ratio represented by (Br) :( I) is in the range of 10:90 to 30:70. This is the same regardless of the presence or absence of the added metal and the type of the rare gas. By setting the amount and ratio in this manner, it is possible to increase particularly the emission intensity of 450 to 500 nm, and to suppress the deterioration of the starting performance.
[0019]
When the amount of bromine added is increased, the starting performance tends to decrease. However, when the bromine ratio is 30% or less, the starting performance is not significantly decreased as compared with the case where bromine is not added (that is, iodine only). In addition, even when the start-up performance is reduced to a level that is not negligible in practice, if the addition amount is 30% or less, light emission due to sputtering of the electrode material can be achieved by reducing the sealing pressure of the rare gas. Without causing problems such as blackening of the end of the tube, it is possible to suppress a decrease in starting performance to the extent that there is no problem. The pressure in this case is preferably 5 to 10 torr at an arc tube temperature of 25 ° C., for example. When bromine is added in excess of 30%, another problem such as blackening occurs when the pressure that can suppress the deterioration of the starting performance is reduced when the method of reducing the sealing pressure of the rare gas is used. Such a method cannot be adopted.
[0020]
In order to ensure the starting performance when adding bromine in the above amount and proportion, in particular, the rare gas is argon gas, and the partial pressure in the arc tube is 5 to 10 torr at the arc tube temperature of 25 ° C. It is preferable to enclose so that the startability deterioration due to bromine encapsulation can be effectively offset.
[0021]
【Example】
The characteristics of the prototype metal vapor discharge lamp will be described below. The prototype metal vapor discharge lamp has the same structure as that shown in FIG. 1, the emission length of the quartz arc tube is 500 mm, the inner diameter of the arc tube is 22 mm, the lamp power is 8 kW, and the lamp voltage is 750 V. The lamp current was 11.8 A.
[0022]
Example 1
(Fe) is 6 × 10 ⁻⁷ (mol / cc), (Sn) is 2 × 10 ⁻⁷ (mol / cc), (I) + (Br) is 8 × 10 ⁻⁷ (mol / cc), A lamp in which (Br) :( I) was changed in the range of 0: 100 to 100: 0 was made as an experiment. In addition, 200 mg of mercury was sealed, and Ar was used as a rare gas.
[0023]
A graph in which the wavelength range of 300 to 500 nm is divided every 50 nm with respect to the emission intensity of these lamps, and the relative values are displayed with reference to the lamp value of (Br) :( I) = 0: 100 in the integrated value of each wavelength section. As shown in FIG.
[0024]
As can be seen from the figure, the integrated value in the section of 300 to 350 nm monotonously decreased from 100% to 87% with respect to the increase in the bromine encapsulation ratio. The integrated values in the section of 350 to 400 nm and 400 to 450 nm were flat when (Br) :( I) was 30:70 to 100: 0, and the relative intensity ratio was 114 to 133%. Especially in the case of 450 to 500 nm, the difference appears remarkably, even if the bromine ratio is small, the effect is large, the (Br) ratio is 10%, the relative energy ratio is increased to 130%, and the (Br) ratio is further increased. Although the rate of increase was moderate, the (Br) ratio was 75% and the relative ratio exceeded 200%. Thus, it has been found that the emission energy in the wavelength range of 450 to 500 nm is about 130% or more with respect to the case where only iodine is used as the halogen when the bromine ratio is 10% or more.
[0025]
FIG. 5 shows the starting characteristics of a lamp in which the sealing ratio of iodine and bromine is changed and argon gas is sealed as starting gas at room temperature at 5, 10, and 15 torr, respectively. The measuring method is to turn on and off the lamp once with an air-cooled ultraviolet irradiation device, and after cooling for 10 minutes, apply a sine wave voltage with an effective value of 1000 V as shown in FIG. 6 between the electrodes of the lamp, Further, a pulse waveform having a half-value width of about 80 (μS) was superimposed, and the value at which the lamp reached discharge breakdown was measured by changing the pulse peak value. Hereinafter, this value is referred to as a starting voltage.
[0026]
From FIG. 5, it can be seen that the starting voltage increases as the bromine encapsulation ratio increases. However, in the case of (Br) :( I) = 30: 70 in the case of 10 torr of argon, the starting voltage is equivalent to that of a conventional lamp in which argon gas is sealed at 15 torr and only iodine is used as halogen. I understand.
In other words, in order to enable the lamp of the present invention to be started with a conventional ballast, it can be seen that (Br) should have an enclosure ratio of 30% or less of the total halogen and the enclosed argon pressure should be 10 torr or less.
[0027]
However, the lower the Ar gas pressure, the lower the starting voltage. However, when the pressure is less than 5 torr, sputtering of the electrode material is severe when starting the lamp, and the end of the arc tube is markedly blackened.
[0028]
(Example 2)
As a second embodiment, the case where the tin of the first embodiment is replaced with lead will be described.
[0029]
FIG. 3 is a graph in which the wavelength range of 300 to 500 nm is divided for every 50 nm with respect to the emission intensity of this lamp, and the integrated values of each wavelength section are displayed relative to each other on the basis of (Br) :( I) = 0: 100. As can be seen from the figure, the integral value in the section of 300 to 350 nm monotonously decreased from 100% to 88% with increasing bromine encapsulation ratio. In the case of 350 to 400 nm and 400 to 450 nm, (Br) :( I) was 30:70 to 100: 0 and the relative intensity ratio was 113 to 135%. Especially in the case of 450 to 500 nm, the difference appears remarkably, even if the bromine ratio is small, the effect is large, the (Br) ratio is 10%, the relative energy ratio is increased to 130%, and the (Br) ratio is further increased. Although the rate of increase was moderate, the (Br) ratio was 75% and the relative ratio was 200%. Thus, it has been found that the emission energy in the wavelength region of 450 to 500 nm is 130% or more with respect to the case where only iodine is used as the halogen when the bromine ratio is 10% or more.
[0030]
The same results as in the first embodiment were obtained when the argon pressure was changed with respect to the lamp starting voltage.
[0031]
(Example 3)
The third embodiment is a case in which, in the first embodiment, an additional metal such as lead or tin is not encapsulated but the amount of iron is increased by that amount and encapsulated.
[0032]
FIG. 4 is a graph in which the wavelength range of 301 to 500 nm is divided every 50 nm with respect to the emission intensity of this lamp, and the integrated values of each wavelength section are displayed relative to each other on the basis of (Br) :( I) = 0: 100. As can be seen from the figure, the integral value in the section of 300 to 350 nm monotonously decreased from 100 to 85% with increasing bromine encapsulation ratio. In the case of 350 to 400 nm and 400 to 450 nm, (Br) :( I) was 30:70 to 100: 0, and the relative intensity ratio was around 130%. Especially in the case of 450 to 500 nm, the difference appears remarkably, even if the bromine ratio is small, the effect is large, the (Br) ratio is 10%, the relative energy ratio is increased to 130%, and the (Br) ratio is further increased. Although the rate of increase was moderate, the (Br) ratio was 75% and the relative ratio was 200%. Thus, it has been found that the emission energy in the wavelength region of 450 to 500 nm is 130% or more with respect to the case where only iodine is used as the halogen when the bromine ratio is 10% or more.
[0033]
The same results as in the first embodiment were obtained when the argon gas sealing pressure was changed with respect to the lamp starting voltage.
[0034]
That is, when the additive metal is tin or lead with respect to the emission intensity of the iron-containing metal halide lamp using iron as the main light emitting metal, or in other words, at least the iron enclosed as the main light emitting metal is the total number of encapsulated metals. When the ratio of (Br) :( I) is in the range of 10:90 to 30:70, the relative intensity ratio of 450 to 500 nm is 130 to 180%. In the range of Br) :( I) = 30: 70 to 100: 0, a very large improvement of 170 to 200% was observed.
[0035]
Regarding the starting voltage, it is estimated that the change in the additive metal as described above is due to the fact that there is no difference in the pressure of the bromine gas (Br ₂ ) at the time of starting the lamp. Indicated. That is, the starting voltage increases as the bromine sealing ratio increases. However, if (Br) :( I) is in the range of 10:90 to 30:70, 5-10 torr of argon is sealed as a starting rare gas when the lamp is manufactured. Thus, a lamp having a starting voltage comparable to that of a lamp in which only iodine as a halogen of a conventional lamp and argon as a starting gas was sealed at 15 torr was obtained.
[0036]
The startability is considered to be influenced not only by the (Br) :( I) encapsulation ratio but also by the halogen sum of (Br) + (I). The inventor fixed an appropriate amount of mercury (around 200 mg) in the lamp having the structure shown in FIG. 1, argon in the starting gas at 10 torr, (Br) :( I) fixed at 30:70 (Fe) with (Br) + When the same amount of (I) is encapsulated, and when an appropriate amount of mercury (around 200 mg), argon 15 torr, (Fe) and (I) are encapsulated in the same amount, the halogen sum of (Br) + (I) is 2 × FIG. 7 shows the results of investigating the starting voltage while changing to 10 ⁻⁷ , 8 × 10 ⁻⁷ , and 14 × 10 ⁻⁷ (mol / cc).
[0037]
The horizontal axis represents (Br) + (I), and the vertical axis represents the starting voltage. As can be seen from the figure, in this range of halogen sums, both had almost the same starting voltage.
[0038]
Eventually, the halogen sum of (Br) + (I) is in the range of 2 × 10 ^{−7 to} 14 × 10 ⁻⁷ (mol / cc), and (Br) :( I) is in the range of 10:90 to 30:70. Then, if 5 to 10 torr of argon is sealed as a starting rare gas when manufacturing the lamp, the lamp has a startability comparable to that of a conventional lamp, and can be started with a conventional ballast.
[0039]
【The invention's effect】
According to the present invention, it is possible to provide a lamp that has enhanced emission energy in the range of 350 to 500 nm and can be started with a conventional ballast.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing the structure of a metal vapor discharge lamp.
FIG. 2 is a graph showing changes in emission intensity when the encapsulation ratio of iodine and bromine, which are encapsulated halogens, is changed.
FIG. 3 is a graph showing a change in emission intensity when the encapsulation ratio of iodine and bromine as encapsulated halogens is changed.
FIG. 4 is a graph showing a change in emission intensity when the encapsulation ratio of iodine and bromine, which are encapsulated halogens, is changed, in which the encapsulated metal is only iron.
FIG. 5 is a diagram showing a starting voltage when an enclosure ratio of iodine and bromine is changed at an enclosed argon gas pressure of 5, 10, and 15 torr.
FIG. 6 is a diagram showing a starting voltage waveform applied between electrodes of a lamp.
FIG. 7 is a diagram showing a starting voltage when the halogen sum is changed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Arc tube 2 ... Electrode 3 ... Molybdenum foil 4 ... Base

Claims (3)

At least mercury for a buffer gas, iron as a luminescent metal, iodine and bromine as halogens, and a starting rare gas are enclosed in the arc tube,
Regarding the number of encapsulated atoms converted per volume inside the arc tube, when (I) is iodine and (Br) is bromine, (Br) + (I) is 2 × 10 ^{−7 to} 14 × 10 ⁻⁷ (mol / cc). And the atomic ratio represented by (Br) :( I) is in the range of 10:90 to 30:70. When at least one kind of lead or tin is enclosed in the arc tube, and the number of encapsulated atoms converted per volume of the arc tube, when lead is represented as (Pb), tin as (Sn), and iron as (Fe), ((Pb) The metal vapor discharge lamp according to claim 1, wherein an encapsulation ratio represented by + (Sn)) / (Fe) is 0.3 or less. 3. The metal vapor discharge lamp according to claim 1, wherein argon gas is enclosed as a starting rare gas, and a partial pressure of the argon gas in the arc tube is 5 to 10 torr.

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