JP2000077027A - Ultraviolet generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultraviolet generating device capable of surely attaining desired ultraviolet rays with less failure, long life and high safety. SOLUTION: In this ultraviolet generating device, a discharge gas 1 is filled in a discharge container 2 constituted of a dielectric. In the case of a low- pressure mercury lamp, the discharge gas 1 is adjusted so that an argon gas adjusts a mercury partial pressure to be several Pa to several tens Pa. An electrode 3 is placed inside near the both ends of the discharge container 2. A shape with a greater surface area is used for the electrode 3. As a material of the electrode 3, tungsten or an alloy whose base metal is tungsten is used. A power source 4 for generating a pulse voltage or a sinewave voltage is connected with the electrode 3. A controller for controlling an impressed voltage, a current, a repetition frequency of pulse and a pulse width is connected with the electrode 3 and the power source 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet ray generating device for generating ultraviolet light by discharging into a discharge gas using an electrode.

[0002]

2. Description of the Related Art Conventionally, ultraviolet light (UV light) has been used to sterilize, disinfect, and decolorize water and sewage, deodorize and decolorize industrial water, bleach pulp, sterilize medical equipment, and the like. Ultraviolet light can typically be generated by an ultraviolet generator such as an ultraviolet lamp. In such an ultraviolet ray generating device, a discharge vessel made of a dielectric is filled with a discharge gas, and a discharge is performed by applying a voltage to an electrode arranged in the discharge gas, thereby generating ultraviolet light. Such an ultraviolet ray generator can be classified into a hot cathode type and a cold cathode type according to the type of electrode used.In recent years, the latter type has been used from the viewpoint of high efficiency and long life. Many.

[0003]

However, in the conventional ultraviolet ray generator, when the discharge input increases, the discharge gas itself causes self-absorption, or excitation occurs at an unintended level, so that emission of a desired wavelength is generated. May not be obtained, and luminance, generation intensity, and efficiency may be saturated. Also, it is not always easy to generate ultraviolet light having a high peak luminance.

[0004] Further, since a metal electrode is provided in a discharge space such as a hot cathode or a cold cathode, when the discharge input increases, the metal of the electrode evaporates and the electrode itself is consumed. May adhere to the inner wall. The adhesion of the evaporated metal to the discharge vessel impedes the transmission of ultraviolet light,
Since the efficiency with which ultraviolet light is emitted to the outside is reduced, the life of the discharge unit is shortened.

Further, when a rectangular wave is applied, a high voltage is required to ignite the discharge. However, since this voltage is higher than the voltage required to maintain the discharge, it is assumed that the discharge is ignited. At the same time, a large current flows and the power supply may be damaged.

[0006] The present invention has been proposed to solve the problems of the prior art as described above.
It is an object of the present invention to provide an ultraviolet ray generator which can reliably obtain a desired ultraviolet ray, has less failures, has a long service life and high safety.

[0007]

In order to achieve the above-mentioned object, the present invention provides a discharge space comprising a dielectric filled with a discharge gas, and an electrode which discharges by applying a voltage in the discharge space. Are provided with the following technical features.

That is, the invention according to claim 1 is characterized in that the electrode has at least one of a groove, a hole, and a bent portion. According to the first aspect of the present invention, at least one of the groove, the hole, and the bent portion formed in the electrode increases the surface area of the electrode and has a structure in which ions are confined, so that the current density is reduced. Therefore, even if the discharge input increases, the metal of the electrode is less likely to evaporate due to collision with electrons or the like.

The invention according to claim 2 is characterized in that it is formed of tungsten or an alloy containing tungsten as a base material. According to the second aspect of the present invention, even when the discharge input increases, the metal of the electrode is less likely to evaporate due to collision with electrons and the like, and the consumption of the electrode is suppressed.

According to a third aspect of the present invention, in the ultraviolet ray generating device according to the first or second aspect, the power supply is a pulse power supply for generating a pulse voltage.
According to the third aspect of the present invention, light emission of a desired wavelength can be easily obtained by applying a pulse voltage.

According to a fourth aspect of the present invention, in the ultraviolet generating apparatus of the third aspect, control means for controlling a pulse voltage, a current, a pulse repetition frequency and a pulse width applied to the electrode is provided. It is characterized by. According to the fourth aspect of the present invention, it is possible to generate ultraviolet light having a high peak luminance under the control of the control means.

According to a fifth aspect of the present invention, in the ultraviolet generating apparatus according to the fourth aspect, the control means has a pulse duty control section for controlling a repetition frequency and a pulse duty width of the pulse duty. .
According to the fifth aspect of the present invention, by controlling the pulse duty, a high peak luminance of the ultraviolet light can be maintained.

According to a sixth aspect of the present invention, in the ultraviolet generating apparatus according to any one of the first to fifth aspects, the voltage is a combination of a voltage for firing the discharge and a voltage for maintaining the discharge. It is a pulse voltage. In the above-described invention, since the applied voltage is a combination of a high voltage for igniting the discharge and a voltage for maintaining the discharge, a large current flows at the same time as the discharge is ignited, and Is not destroyed.

According to a seventh aspect of the present invention, in the ultraviolet generating apparatus according to any one of the third to fifth aspects, the pulse voltage causes the discharge to be ignited at the beginning of each pulse duty cycle. It is characterized in that a voltage pulse is applied. According to the seventh aspect of the present invention, since a high-voltage pulse for igniting a discharge is applied at the beginning of each pulse duty cycle, a large current flows at the same time as the discharge is ignited. The power supply will not be damaged.

According to an eighth aspect of the present invention, in the ultraviolet ray generating device according to any one of the third to fifth aspects, the pulse voltage causes the discharge to be ignited at the beginning of each pulse duty cycle. A combination of a voltage pulse and a voltage pulse for maintaining discharge is applied. According to the eighth aspect of the present invention, at the beginning of each cycle of the pulse duty cycle, a pulse of a high voltage for firing the discharge and a pulse of a voltage for maintaining the discharge are applied. A large current flows at the same time as the ignition, which does not damage the power supply.

According to a ninth aspect of the present invention, in the ultraviolet ray generating device according to any one of the fourth to eighth aspects, a luminance monitor is connected to the control means. According to the ninth aspect, by controlling the applied voltage, the current, the pulse repetition frequency and the pulse width based on the output result of the luminance monitor, the peak luminance, the average luminance, and the light emission interval can be appropriately adjusted. It can generate controlled ultraviolet light.

According to a tenth aspect of the present invention, in the ultraviolet ray generating device according to any one of the first to ninth aspects, the dielectric is tubular, the applied stress is p (Pa), and the radius of the tube is r. (Mm), when the thickness of the dielectric is t (mm), the value of p × r / t is set so as not to exceed the breaking stress of the material of the dielectric, and It is characterized in that the thickness t is set. According to the tenth aspect of the present invention, it is possible to prevent breakage due to external pressure or internal pressure by the thickness of the dielectric.

The invention according to claim 11 is the invention according to claims 1 to 10
In the ultraviolet ray generating device according to any one of the above, a wavelength conversion material is applied to a front surface or a rear surface of the dielectric. In the invention according to claim 11 as described above, the wavelength conversion material applied to the dielectric material provides:
Convert the ultraviolet light emitted by the discharge into light of different wavelength,
That light can be used.

The invention according to claim 12 is the invention according to claims 1 to 10
In the ultraviolet ray generating device according to any one of the above, a substrate coated with a wavelength conversion material is disposed near the dielectric. In the twelfth aspect of the present invention, ultraviolet light emitted by discharge is converted into light of a different wavelength by a wavelength conversion material applied to a substrate disposed near a dielectric, and the light is used. be able to.

The invention according to claim 13 is the invention according to claims 1 to 10
In the ultraviolet ray generating device according to any one of the above, a wavelength conversion crystal is arranged near the dielectric. In the invention of claim 13 as described above,
Ultraviolet light emitted by discharge can be converted to light of a different wavelength by a wavelength conversion crystal arranged near the dielectric, and the light can be used.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (1) First Embodiment (Structure) An embodiment corresponding to the first to fourth aspects of the present invention will be described below with reference to FIGS. That is, as shown in FIG. 1, a discharge vessel 2 made of a dielectric material
Are filled with a discharge gas 1. In the case of a low-pressure mercury lamp, the discharge gas 1 is adjusted so that the partial pressure of mercury in the argon gas is several Pa to several tens Pa. Electrodes 3 are arranged in the vicinity of both ends of the discharge vessel 2. The electrode 2 has a large surface area. For example, as shown in FIG. 2, there are various types such as a cylindrical shape (a), a U-shaped plate shape (b), a multilayer slit shape (c), a multi-diaphragm cylindrical shape with a groove (d), and a horn shape (e). Conceivable.

The electrode 2 is made of tungsten or an alloy containing tungsten as a base material.
For example, it is conceivable to use tungsten mixed with a small amount (0.1% to 5%) of thorium oxide. Also,
A power supply 4 for generating a pulse voltage or a sine wave voltage is connected to the electrode 3. Further, although not shown,
A control device for controlling the applied voltage, current, pulse repetition frequency and pulse width is connected to the electrode 3 and the power supply 4.

(Operation and Effect) The operation and effect of the present embodiment as described above are as follows. That is, a pulse voltage or a sine wave voltage is applied to the electrode 2 in the atmosphere of the discharge gas 1 by the power supply 4 to generate a discharge 5. Then
The discharge generates ultraviolet light 6. As shown in FIG. 2, the electrode 2 has a large surface area, so that a large amount of current can flow, and consumption for sputtering due to electric discharge can be suppressed.

Since the material of the electrode 2 is also tungsten or an alloy containing tungsten as a base material,
Wear can be reduced. In particular, when a small amount of thorium oxide is mixed in, the current per unit surface area of the electrode 2 can be secured, so that the consumption is small.

Further, as shown in FIG. 3, by controlling the applied voltage, current, pulse repetition frequency and pulse width by a control device, it is possible to generate ultraviolet light having a high peak luminance.

(2) Second Embodiment An embodiment corresponding to the invention described in claim 5 will be described below with reference to FIG. That is, in the present embodiment, the control device in the first embodiment has a pulse duty control unit that controls the pulse duty repetition frequency and the pulse duty width.
Then, for example, in the case of a low-pressure mercury lamp, the bipolar diffusion time is 5 msec by the pulse duty control unit.
Considering the average lifetime of excited Hg atoms 25 μsec and the energy relaxation time of electrons, the pulse duty repetition frequency is 300 Hz or less, and the pulse repetition frequency is 1
Control over kHz. According to the present embodiment as described above, high peak luminance of ultraviolet light can be maintained by pulse duty control.

Even when a sine wave voltage is applied instead of a pulse voltage, the pulse duty control is performed, and the high peak luminance of the ultraviolet light is maintained by controlling the pulse duty repetition frequency and the pulse duty width. Can be. For example, in the case of a low-pressure mercury lamp, the repetition frequency of the pulse duty is 300 in consideration of the ambipolar diffusion time of 5 msec, the average lifetime of excited Hg atoms of 25 μsec, and the energy relaxation time of electrons.
By controlling the pulse repetition frequency at 1 Hz or less, the control can be performed such that the high luminance of the peak of the ultraviolet light does not decrease.

(3) Third Embodiment An embodiment corresponding to the invention described in claims 6 to 8 is shown in FIGS.
7 will be described below. That is, in the present embodiment, the voltage applied to the electrode 3 by the power supply 4 is, as shown in FIG. 5, a waveform having a combination of a high voltage for igniting discharge and a low voltage for maintaining discharge. The pulse voltage is used. As shown in FIG. 6, a high-voltage pulse for igniting a discharge may be applied at the beginning of each pulse duty cycle. Further, as shown in FIG. 7, at the beginning of each cycle of the pulse duty cycle, a combination of a high voltage pulse for igniting the discharge and a low voltage pulse for maintaining the discharge may be applied. Good.

According to the present embodiment as described above, it is possible to prevent a large current from flowing at the same time as the discharge is ignited, thereby preventing the power supply from being damaged. Can be provided.

(4) Fourth Embodiment An embodiment corresponding to the invention described in claim 9 will be described below with reference to FIG. That is, in the present embodiment, the luminance monitor 8 is connected to the power supply 4 and the control device in the first embodiment. Then, by controlling the applied voltage, the current, the pulse repetition frequency and the pulse width based on the output result of the luminance monitor 8, the peak luminance, the average luminance, and the light emission interval are generated so that the ultraviolet light is appropriately controlled. be able to.

(5) Fifth Embodiment (Configuration) An embodiment corresponding to the invention described in claim 10 will be described below with reference to FIG. That is, the dielectric constituting the discharge vessel 2 has a thickness that does not cause damage due to external pressure or internal pressure. For example, in the case of a tubular dielectric, the maximum annular stress S (Pa) is given by the applied stress (differential pressure) p.
(Pa), the radius of the tube is r (mm), and the thickness of the dielectric is t
(Mm), S is expressed by S = p × r / t, so that S is designed not to exceed the breaking stress of the dielectric material.

(Effects) According to the present embodiment as described above, by setting the dielectric to an appropriate thickness,
The discharge vessel 2 is prevented from being damaged by external pressure or internal pressure, and safety and durability can be improved.

(6) Sixth Embodiment An embodiment corresponding to the invention described in claim 11 will be described with reference to FIG.
This will be described below with reference to FIG. That is, in the present embodiment, the wavelength conversion material such as the phosphor 13 is applied to the front or back surface of the dielectric constituting the discharge vessel 2. According to the present embodiment, since the ultraviolet light emitted by the discharge is converted into light having different wavelengths by the phosphor 13, the light can be used.
In addition, as shown in FIG. 11, by disposing a substrate 14 or the like coated with a wavelength conversion material such as a phosphor outside the discharge vessel 2, the ultraviolet light 6 emitted by the discharge is different depending on the phosphor. Since the light can be converted into light 6 ′ having the wavelength, the same effect as described above can be obtained.

(7) Other Embodiments The present invention is not limited to the above embodiments, and the shape, size, number, material, etc. of each member can be changed as appropriate. For example, the shape of the discharge vessel 2 may be a cylindrical rod shape as shown in FIG. 12, a flat plate shape as shown in FIG. 13, or a double tube structure as shown in FIGS. 14 and 15. Good. Further, the material of the discharge vessel 2 is not limited to the dielectric material alone, but may be partially composed of another material such as a metal.

Further, as shown in FIG. 9, it is also possible to provide a reinforcing column 13 inside the discharge vessel 2. For example, in the case of a plate-type dielectric, the maximum stress S (Pa) is p (Pa) as the acting stress (differential pressure), and d (m) as the distance between the columns.
m), assuming that the thickness of the dielectric is t (mm), p = 0.8
Since it is expressed by 4 × S × t ² / (d / 2) ² , the distance d should not exceed the breaking stress S of the dielectric material.
According to such an embodiment, since the stress caused by the external pressure or the internal pressure can be dispersed by the support columns 13, the breakage of the discharge vessel 2 can be prevented, and the dielectric material constituting the discharge space can be made thin. it can.

The above-described structure can be obtained by disposing a wavelength conversion crystal such as KDP on the front or back surface of the dielectric constituting the discharge vessel 2 or disposing a wavelength conversion crystal such as KDP outside the discharge vessel 2. The same operation and effect as in the sixth embodiment can be obtained.

As the discharge gas, a mixture of Hg and an argon gas was used. However, a mixed gas of Hg and another rare gas, a rare gas alone, a mixed gas of sulfur and a rare gas, and a mixed gas of different kinds of rare gases were used. Gas or the like may be used.

[0038]

As described above, according to the present invention, it is possible to provide an ultraviolet ray generator which can reliably obtain a desired ultraviolet ray, has few failures, has a long service life and high safety.

[Brief description of the drawings]

FIG. 1 is a simplified configuration diagram showing a first embodiment of an ultraviolet ray generator according to the present invention.

FIGS. 2A and 2B are perspective views showing electrode shapes in the embodiment of FIG. 1, wherein FIG. 2A is a cylindrical shape, FIG. 2B is a U-shaped plate shape, FIG. (D) is a cylindrical type with a multiple throttle groove, and (e) is a trumpet type.

FIG. 3 is a graph showing a control example by the control device according to the embodiment of FIG. 1;

FIG. 4 is a graph showing a control example by a pulse duty control unit in a second embodiment of the ultraviolet ray generator of the present invention.

FIG. 5 is a graph showing an example of an applied voltage in a third embodiment of the ultraviolet ray generator according to the present invention.

FIG. 6 is a graph showing another example of the applied voltage in the third embodiment of the ultraviolet ray generator of the present invention.

FIG. 7 is a graph showing another example of the applied voltage in the third embodiment of the ultraviolet ray generator of the present invention.

FIG. 8 is a simplified configuration diagram showing a fourth embodiment of the ultraviolet ray generator according to the present invention.

FIG. 9 is a simplified configuration diagram showing a fifth embodiment of the ultraviolet ray generator according to the present invention.

FIG. 10 is a simplified configuration diagram showing a sixth embodiment of the ultraviolet ray generator of the present invention.

FIG. 11 is a simplified configuration diagram showing another example of the sixth embodiment of the ultraviolet ray generator of the present invention.

FIG. 12 is a perspective view showing a cylindrical rod-shaped discharge vessel in another embodiment of the ultraviolet ray generator of the present invention.

FIG. 13 is a perspective view showing a flat discharge vessel in another embodiment of the ultraviolet ray generator of the present invention.

FIG. 14 is a perspective view showing a discharge vessel having a double-tube structure in another embodiment of the ultraviolet ray generator of the present invention.

15 is an axial sectional view of the discharge vessel of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Discharge gas 2 ... Discharge container 3 ... Electrode 4 ... Power supply 5 ... Discharge 6 ... Ultraviolet light 8 ... Luminance monitor 9 ... Dielectric 10 ... Pressure 11 ... Support | pillar 13 ... Phosphor 14 ... Substrate

Claims (13)

[Claims] 1. An ultraviolet generator in which a discharge space is formed by a dielectric material filled with a discharge gas, and an electrode that discharges by application of a voltage is disposed in the discharge space. An ultraviolet generating device, wherein at least one of a portion and a bent portion is formed. 2. An ultraviolet generator in which a discharge space is formed by a dielectric material filled with a discharge gas, and an electrode that discharges by applying a voltage is disposed in the discharge space, wherein the electrode is made of tungsten or tungsten. An ultraviolet ray generator characterized by being formed of an alloy as a base material. 3. The ultraviolet generator according to claim 1, wherein the power supply is a pulse power supply that generates a pulse voltage. 4. The ultraviolet generator according to claim 3, further comprising control means for controlling a pulse voltage, a current, a pulse repetition frequency and a pulse width applied to the electrode. 5. The ultraviolet generating apparatus according to claim 4, wherein said control means has a pulse duty control section for controlling a pulse duty repetition frequency and a pulse duty width. 6. The ultraviolet ray generator according to claim 1, wherein the voltage is a pulse voltage in which a voltage for firing a discharge and a voltage for maintaining the discharge are combined. apparatus. 7. The pulse voltage according to claim 3, wherein a pulse of a voltage for firing discharge is applied at the beginning of each pulse duty cycle.
6. The ultraviolet ray generator according to any one of items 5 to 5. 8. A combination of a pulse of a voltage for igniting a discharge and a pulse of a voltage for maintaining a discharge is applied to the pulse voltage at the beginning of each cycle of a pulse duty cycle. The ultraviolet ray generator according to any one of claims 3 to 5. 9. The apparatus according to claim 4, wherein a luminance monitor is connected to said control means.
Item 7. The ultraviolet ray generator according to the item 1. 10. When the dielectric is tubular, the acting stress is p (Pa), the radius of the tube is r (mm), and the thickness of the dielectric is t (mm), p × r / The thickness t of the dielectric is set so that the value of t does not exceed the breaking stress of the material of the dielectric, The thickness t of the dielectric according to any one of claims 1 to 9, The ultraviolet generator according to the above. 11. The dielectric material according to claim 1, wherein a wavelength conversion material is applied to a front surface or a back surface of the dielectric.
The ultraviolet ray generator according to any one of items 10 to 10. 12. The ultraviolet generator according to claim 1, wherein a substrate coated with a wavelength conversion material is arranged near the dielectric. 13. The ultraviolet ray generating apparatus according to claim 1, wherein a wavelength conversion crystal is arranged near the dielectric.