JP7682469B2 - Ultraviolet irradiation device, ozone generator, and excimer lamp lighting method - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Act On January 16, 2021, Oak Manufacturing Co., Ltd., the right holder, disclosed the present invention on its website. In addition, on November 16, 2020, Oak Manufacturing Co., Ltd., the right holder, was interviewed by BS Television Tokyo Co., Ltd. regarding the present invention, and the present invention was disclosed on the company's program on January 16, 2021. Furthermore, on July 7, 2021, Oak Manufacturing Co., Ltd., the right holder, began selling an ozone generator related to the present invention.

The present invention relates to excimer lamps, and in particular to lamp lighting control.

In an excimer lamp, an electrode (hereafter referred to as the outer electrode) is disposed on the outer periphery of a discharge vessel made of a dielectric material such as quartz glass. Meanwhile, inside the discharge vessel, an electrode (hereafter referred to as the inner electrode) is disposed along the lamp axis, and a rare gas such as xenon gas is sealed inside the discharge vessel. By applying a voltage between the inner and outer electrodes, a dielectric barrier discharge or a capacitively coupled high-frequency discharge occurs in the discharge space inside the discharge vessel, and ultraviolet light is emitted as excimer light (see, for example, Patent Document 1).

Patent No. 6423642

For example, when using an excimer lamp in an ozone generator, the amount of ozone required to be generated varies depending on the usage environment and conditions, and there are cases where stable generation of ozone at a low concentration is required. Also, in small ozone generators that use batteries, there are limitations on the size and power of the excimer lamp, and ozone generation with reduced power consumption is required.

Therefore, there is a need for excimer lamp lighting control that can effectively irradiate ultraviolet light depending on the usage environment of the ozone generator, etc.

The ultraviolet irradiation device according to one aspect of the present invention is applicable to an ozone generator and includes an excimer lamp and a control unit that controls the lighting of the excimer lamp. The control unit then repeatedly turns the excimer lamp on and off so as to continue the discharge in a transient state. In this lighting control, the frequency f2 at which the excimer lamp is periodically turned on and off can be set lower than the frequency f1 of the voltage applied to the excimer lamp, and for example, the frequency f2 can be set in the range of 1 to 60 Hz.

For example, the ozone generator can be equipped with an operation detection switch that detects an input operation by a user. The operation detection switch can be configured to detect an input operation at a frequency of f3 = f2 x n (n is a natural number).

An ozone generator according to another aspect of the present invention includes an excimer lamp and a control unit that controls the lighting of the excimer lamp, and the control unit repeatedly turns the excimer lamp on and off so as to continue the transient discharge. For example, it is possible to perform lighting control that repeatedly turns the lamp on and off so that the amount of ozone generated during repeated transient discharge is less than half the amount of ozone generated during steady-state discharge.

The ozone generator can include a flow passage tube in which the excimer lamp is disposed. Lighting can be controlled so that the flow rate of the oxygen-containing fluid flowing through the flow passage tube is 1 m ³ /min or less.

For example, the ozone generator can be equipped with an operation detection switch that detects an input operation by a user. The operation detection switch can be configured to detect an input operation at a frequency of f3 = f2 x n (n is a natural number).

Another aspect of the present invention is a method for lighting an excimer lamp that has an electrode at least partially exposed inside the discharge vessel, and repeatedly turns the excimer lamp on and off to continue the discharge in a transient state.

The present invention makes it possible to provide an excimer lamp that can effectively irradiate ultraviolet light in ozone generators and the like.

1 is a schematic cross-sectional view of an excimer lamp in an ozone generator according to the present embodiment, viewed from the side. FIG. FIG. 1 is a block diagram of an ozone generator.

Below, we will explain an ozone generator equipped with an excimer lamp, which is an embodiment of the present invention, with reference to the drawings.

Figure 1 is a schematic cross-sectional view of an excimer lamp in an ozone generator according to this embodiment, viewed from the side.

The ozone generator 100 includes an excimer lamp 10, and is controlled by a control unit (not shown). The excimer lamp 10 is disposed in a flow path pipe 90 through which a raw material gas containing oxygen flows. While the raw material gas is caused to flow around the excimer lamp 10 by an intake fan (not shown), the excimer lamp 10 irradiates the raw material gas with ultraviolet light to generate ozone.

The ozone generator 100 is configured here as a low-concentration ozone generator, and is configured as a small battery-powered device. That is, the ozone generator 100 incorporating an ultraviolet irradiation device equipped with an excimer lamp 10 and a control unit capable of controlling the lighting of the excimer lamp 10 can be installed sideways so that the flow path tube 90 is aligned horizontally, and can also be installed directly above so that the flow path tube 90 is aligned vertically.

The excimer lamp 10 is equipped with a discharge vessel 20, which is sealed at both ends of a cylindrical section having a constant inner diameter along the lamp axis C, and is made of a dielectric material such as quartz glass that transmits ultraviolet light. The cylindrical section of the discharge vessel 20 has a small diameter section 21 formed integrally with the tip end via the small diameter section, and a sealing tube 22 formed integrally with the rear end via the small diameter section. That is, the small diameter section 21 and the small diameter section are formed integrally with the tip end of the cylindrical section, and the sealing tube 22 and the small diameter section are formed integrally with the rear end of the cylindrical section. A rare gas such as xenon is sealed in the discharge space S inside the discharge vessel 20.

In the sealed tube 22, the inner electrode 40 is arranged to extend along the lamp axis C, and its electrode tip (hereinafter referred to as tip) 40T is exposed to the discharge space S and faces the cylindrical part of the discharge vessel 20 along the lamp radial direction. That is, only the tip 40T of the inner electrode 40 faces the cylindrical part of the discharge vessel 20 along the lamp radial direction, and the other part of the inner electrode 40 faces the reduced diameter part of the discharge vessel 20 along the lamp radial direction, and does not face the cylindrical part of the discharge vessel 20. On the other hand, the rear end side of the inner electrode 40 is connected to the power supply line (hereinafter referred to as inner power supply line) 25 via the sealing foil (metal foil) 24.

An outer electrode 50 is provided on the outer surface 20S of the discharge vessel 20. The outer electrode 50 exposes the outer surface 20S of the discharge vessel 20, and is provided with a discharge electrode portion (hereinafter referred to as the spiral electrode portion) 51, which is wound with a conductive wire in a spiral shape so as not to block the ultraviolet rays emitted from the discharge inside the discharge vessel and mainly contributes to the formation of a discharge inside the discharge vessel, and holding electrode portions (hereinafter referred to as the annular portions) 52, 54, 56, which hold and electrically connect the spiral electrode portion 51 and are made of a conductive plate wrapped around them in a ring shape to cover the outer surface 20S of the discharge vessel 20.

The spiral electrode portion 51 is wound in close contact with the outer surface 20S along the lamp axis C from the tip to the rear end of the cylindrical portion of the discharge vessel 20, and is electrically connected to the annular portions 52, 54, and 56 by welding or wrapping them, suppressing the formation of gaps in the outer surface of the discharge vessel 20 and movement along the lamp axis C. The spiral electrode portion 51 is disposed on the outer surface 20S so as to generate a thin-line discharge extending throughout the entire range of the discharge space S in the lamp axis direction. The annular portions 52 and 56 are located at both ends of the spiral electrode portion 51 of the discharge vessel 20, and in particular, the annular portion 56 is located so as to face the tip portion 40T of the inner electrode 40 in the lamp radial direction. The annular portion 54 is located near the center of the lamp between them. The annular portion 54 is located closer to the lamp center than the tip portion 40T of the inner electrode 40.

The annular portions 52, 54, 56 are constructed by welding the ends of a conductive plate wound into a cylindrical shape, and by shortening the circumferential length, they come into surface contact with the entire outer surface 20S of the discharge vessel 20, suppressing the formation of gaps in the outer surface 20S of the discharge vessel 20 and movement along the lamp axis C, and holding the spiral electrode portion 51 in place along the lamp axis C. Furthermore, an extension portion 54B is provided on the annular portion 54 located near the center of the lamp.

The extension portion 54B extends in a direction away from the outer surface of the discharge vessel (here, it extends linearly along the lamp diameter direction), and its tip portion 54BT is connected to the earth side outer power supply line 70 at the connection portion BT.

The shortest distance between the discharge vessel 20 and the outer power supply line 70, i.e., the distance D from the outer surface 20S of the discharge vessel 20 to the connection part BT, can be determined taking into consideration the flow conditions of the raw material gas and processing fluid flowing along the periphery of the discharge vessel 20, and the ultraviolet illuminance in the area where the outer power supply line 70 and the connection part BT are located. For example, in the case of ultraviolet rays with a wavelength of 172 nm, the ultraviolet intensity ratio attenuates to 50% or less after a progression of about 3 mm, and attenuates to 20% or less after a progression of about 6 mm. Considering this, the distance D is determined to be equal to or greater than the distance at which the ultraviolet intensity ratio emitted from the discharge vessel 20 attenuates to 50% (ultraviolet attenuation distance), preferably equal to or greater than the distance at which it attenuates to 20%.

When a high-frequency high voltage is applied between the inner electrode 40 and the outer electrode 50, a dielectric barrier discharge occurs, in which ultraviolet light in the wavelength range of vacuum ultraviolet light, i.e., ultraviolet light with a wavelength of 200 nm or less (e.g., 172 nm), is emitted outside the discharge vessel 20 as excimer light. Ozone is generated as the raw material gas containing oxygen flows around the excimer lamp 10 in the flow tube 90, and the gas containing ozone is released outside the ozone generator 100. This allows for sterilization, deodorization, etc.

Figure 2 is a schematic block diagram of the ozone generator 100. Here, only the configuration related to the lighting control of the excimer lamp 10 is shown.

The control unit 110 controls the operation of the ozone generator 100, including controlling the lighting of the excimer lamp 10. The lamp ON/OFF circuit 120 is connected to the lamp power supply circuit 130, and controls the operation of the lamp power supply circuit 130 so that the excimer lamp 10 can be turned on and off periodically. The battery 140, which supplies power to each circuit, including the control unit 110, is composed of a secondary battery such as a lithium battery, and can be charged via a USB terminal cable.

The ozone generator 100 is provided with an operation unit 150 that is provided in the device housing 100A and is operated to start ozone generation operation, set the ozone generation time, etc. The switch circuit (hereinafter referred to as the operation detection switch) 160 detects input operations made by the user to the operation unit 150 and is composed of a touch sensor. An indicator 170, which is composed of an LED or the like and is provided in the housing 100A, can display the ozone generation time, remaining battery power, etc.

In this embodiment, the excimer lamp 10 is turned off (extinguished) before the unstable discharge state (transient discharge) immediately after lighting (ignition) transitions to a stable discharge state (steady-state discharge), and then turned on again immediately after that. By repeating turning on and off in this manner (hereinafter referred to as periodic lighting), a lighting method is adopted that continuously generates a transient discharge.

In a dielectric barrier discharge, when a voltage is applied at a certain frequency, the discharge continues in the area where the convergent thin line-shaped microplasma discharge occurs, and no discharge occurs in the area where the thin line-shaped microplasma discharge does not occur, which is called a memory effect. Here, in order to reset the so-called memory effect (return to the state before the discharge occurred), a reset lighting operation is performed in which the light is turned off before a steady state discharge that causes a memory effect occurs, and a transient state discharge is repeated.

The periodic lighting is performed based on a frequency f2 that is lower than the frequency f1 of the applied voltage when the excimer lamp 10 is lit by applying a high-frequency high voltage. For example, if the frequency f1 of the applied voltage is set in the range of 1 kHz to 500 kHz, the frequency f2 is set in the range of 1 to 60 Hz. In particular, it may be set in the range of 20 Hz to 40 Hz.

When the excimer lamp 10 is lit by periodic lighting with only the tip 40T of the inner electrode 40 facing the outer electrode 50 (particularly the annular portion 56) along the lamp radial direction, the microplasma discharge is biased toward the tube wall in the discharge vessel 20, and dense uniform discharge is not generated throughout the discharge vessel 20. Therefore, even if the discharge space area along the lamp axis C in the discharge vessel 20 is enlarged, the amount of ozone generated does not increase significantly, and low-concentration ozone (low amount of ozone) can be generated stably. In addition, foreign matter emitted from the inner electrode 40 is not deposited in the area surrounding the discharge space area of the discharge vessel 20, but is deposited on the inner surface of the discharge vessel 20 rearward of the tip 40T of the inner electrode 40, so that ultraviolet rays are prevented from being blocked by the deposits.

In addition, by periodically lighting the excimer lamp 10, the microplasma discharge (discharge column) that occurs in the dielectric barrier discharge occurs in a different position each time the lamp is turned on (reset). This is because the microplasma discharge occurs in a spatial region with low electrical resistance (temperature) at the moment the lamp is turned on again.

By continuously generating a transient discharge while shifting to a spatial region with a relatively low temperature, ultraviolet radiation and ozone generation do not continue in the same region as in a steady-state discharge. Therefore, on the inner surface side of the discharge vessel 20, foreign matter emitted from the inner electrode 40 is prevented from continuing to adhere to or accumulate in the same region, and the ultraviolet rays emitted from the discharge vessel are prevented from being blocked by the deposits, resulting in a decrease in the efficiency of ozone generation. In addition, on the outer surface side of the discharge vessel 20, chemical reactions (oxidation) of foreign matter adhered to or accumulated at the connection between the outer electrode and the power supply line are suppressed, thereby preventing the adhesion of foreign matter, deterioration of the electrode, and abnormal discharge. In addition, the discharge that occurs uniformly within the discharge vessel 20 does not cause a temperature rise throughout the discharge vessel 20, and the temperature rise near the surface of the discharge vessel 20, where the ultraviolet light intensity is high, is suppressed, thereby suppressing thermal decomposition by ozone. Therefore, it is possible to continuously generate low-concentration ozone stably, and the ozone generation time can be extended relative to the battery capacity.

In addition, in order to intentionally generate snaking and flickering, which are considered abnormal discharge conditions when illuminated or exposed to light, a converging, thin line-like microplasma discharge extends from the tip 40T of the internal electrode 40, and irregular and complex periodic changes constantly occur along the inner surface of the discharge vessel 20. By creating such a discharge state, ultraviolet light is not continuously irradiated onto the same area of the discharge vessel 20, and a visually dramatic transient discharge is repeated, allowing the lamp to blend in with interior designs even when installed indoors.

Since the ultraviolet illuminance emitted from the discharge in the transient state is lower than that emitted from the discharge in the steady state, if the discharge in the transient state is continued, the amount of ozone generated will be less than half of the amount generated by the discharge in the steady state. In addition, in order to continue the generation of ozone at a low concentration, the operation of the intake fan 180 is controlled so that the flow rate of the raw material gas is 1 ^m3 /min or less.

The operation detection switch 160 monitors (detects) input operations to the operation unit 150 at regular time intervals. The frequency f3 as the detection cycle (detection period) of this operation detection switch 160 is set to n times the frequency f2 (n is a natural number). In other words, monitoring is performed in accordance with the periodic lighting (reset timing) operation of the excimer lamp 10. This prevents any effect on the lamp power supply circuit 130 during discharge in a transient state.

The excimer lamp 10 is not limited to the configuration of a discharge vessel in which a portion of the inner electrode 40 is exposed to the discharge space S described above, and the shape of the discharge vessel and the arrangement of the inner electrode are arbitrary. For example, it can be applied to a double-tube structure lamp. Also, it can be configured not only as a small battery-powered ultraviolet irradiation device or ozone generator, but also as an ultraviolet irradiation device or ozone generator that uses a commercial power source.

REFERENCE SIGNS LIST 10 Excimer lamp 20 Discharge vessel 100 Ozone generator 110 Control unit 120 Lamp ON/OFF circuit

Claims (10)

An excimer lamp,
a control unit that controls the lighting of the excimer lamp,
The ultraviolet irradiation device, wherein the control unit repeatedly turns on and off the excimer lamp so as to continue the discharge in a transient state. The ultraviolet irradiation device according to claim 1, characterized in that the frequency f2 at which the excimer lamp is periodically turned on and off is lower than the frequency f1 of the voltage applied to the excimer lamp. 3. The ultraviolet irradiation device according to claim 2, wherein the frequency f2 is set in the range of 1 to 60 Hz. Further comprising an operation detection switch for detecting an input operation by a user,
4. The ultraviolet irradiation device according to claim 2, wherein the operation detection switch detects an input operation at a frequency of f3=f2×n (n is a natural number). An ozone generator comprising an ultraviolet irradiation device according to any one of claims 1 to 4. An excimer lamp,
a control unit that controls the lighting of the excimer lamp,
2. An ozone generator comprising: a control unit that repeatedly turns on and off the excimer lamp so as to continue a discharge in a transient state. The ozone generator according to claim 6, characterized in that the amount of ozone generated when transient discharge is repeated is less than half the amount of ozone generated when steady-state discharge is performed. a flow path tube in which the excimer lamp is disposed,
8. The ozone generator according to claim 6, wherein the flow rate of the oxygen-containing fluid flowing through the flow pipe is 1 m ³ /min or less. Further comprising an operation detection switch for detecting an input operation by a user,
9. The ozone generator according to claim 6, wherein the operation detection switch detects an input operation at a detection period of frequency f=f×n (f is a frequency at which the excimer lamp is repeatedly turned on and off, and n is a natural number). A method for operating an excimer lamp having an electrode at least a part of which is exposed inside a discharge vessel, comprising the steps of:
A method for operating an excimer lamp, comprising repeatedly turning on and off the excimer lamp so as to continue a discharge in a transient state.

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