JP6379962B2 - Microwave electrodeless lamp and light irradiation device using the same - Google Patents

Description

  The present invention relates to a microwave electrodeless microwave electrodeless lamp and a light irradiation apparatus using the same.

  In recent years, a microwave electrodeless lamp has been developed as a discharge lamp that emits visible light or ultraviolet light. A light irradiation apparatus equipped with a microwave electrodeless lamp typically includes a microwave oscillator, a microwave cavity, and an electrodeless lamp that is a discharge tube (light emitting tube). The electrodeless lamp is detachably supported in the microwave cavity. The microwave cavity is provided with a reflecting mirror for guiding visible light or ultraviolet light from the electrodeless lamp to the light exit. The light exit is provided with a conductive mesh that is impermeable to microwaves but transmissive to visible light or ultraviolet light.

  In the discharge tube, a starting rare gas or an inert gas and a luminescent material are enclosed. By appropriately selecting the luminescent substance, visible light or ultraviolet light having a desired wavelength can be obtained. Ultraviolet rays are divided into a UV-A region having a wavelength of 400 to 315 nm, a UV-B region having a wavelength of 315 to 280 nm, and a UV-C region having a wavelength of 280 to 200 nm. Ultraviolet rays in the UV-A region are used for curing treatment of paints, resins, and the like. Ultraviolet rays in the UV-C region are used for sterilization.

  Conventionally, mercury has been widely used as a luminescent substance. In recent years, there is a strong demand for reducing or not using mercury as an environmentally hazardous substance. That is, there is a growing demand for mercury-free discharge lamps having equivalent emission intensity and emission spectral characteristics in place of conventional mercury-containing discharge lamps.

  Patent Document 1 describes an example of a mercury-free electrodeless lamp. As the luminescent material, zinc, indium iodide, thallium iodide, or the like is used. A light source for illumination that emits greenish white light is obtained. Patent Document 2 describes an example of a mercury-free electrodeless lamp. As the luminescent material, mercury, halogen, iron, nickel, cobalt, palladium, or the like is used. Patent Document 3 describes an example of a mercury-free electroded lamp. Zinc is described to have emission peaks at a wavelength of 214 nm in the UV-C region, a wavelength of 308 nm in the UV-B region, a wavelength of 330 nm and 335 nm in the UV-A region, a wavelength of 468 nm, 472 nm, and 481 nm in the visible region. Yes.

JP-A-8-315782 JP 57-172650 A Special table 2008-516379 gazette

  In recent years, there is an increasing demand for ultraviolet rays having a wavelength of 315 to 400 nm (UV-A region) used for curing treatment of paints, resins, and the like. As an ultraviolet light source in the UV-A region, a microwave electrodeless lamp is suitable. Accordingly, the inventors of the present application have developed a mercury-free microwave electrodeless lamp having emission intensity and emission spectral characteristics equivalent to the mercury-containing type.

  In mercury-free microwave electrodeless lamps, it is important to select the type of luminescent material that can be used in place of mercury and the amount of sealed light. However, it is not preferable to increase the amount of luminescent material enclosed. Further, it is not preferable that the startability is lowered.

  The purpose of the present invention is as a UV light source in the UV-A region, and has the same emission intensity and emission spectral characteristics as a mercury-containing discharge lamp, and further suppresses the amount of luminescent material enclosed and improves startability. An object of the present invention is to provide a mercury-free microwave electrodeless lamp and a light irradiation apparatus using the same.

  The inventor of the present application first studied diligently about the luminescent material. As described in Patent Document 3 (Japanese translations of PCT publication No. 2008-516379), zinc is known to generate emission peaks at wavelengths of 330 nm and 335 nm in the UV-A region. Therefore, in order to improve the emission intensity of ultraviolet rays in the UV-A region, zinc is used as the luminescent material. As described in Patent Document 2 (Japanese Patent Application Laid-Open No. 57-172650), a mercury-free electrodeless lamp uses an iron-based element (iron, nickel, cobalt) and a halide thereof as a luminescent material. It is known. Therefore, the inventors of the present application conducted an experiment and confirmed that it is effective to use an iron-based element (iron, nickel, cobalt) and a halide thereof as a luminescent material in a mercury-free electrodeless lamp.

  Next, the inventor of the present application diligently studied a method for reducing the amount of encapsulated luminescent material. Therefore, it was considered to reduce the inner diameter of the discharge vessel and reduce the volume of the discharge vessel. The inventor of the present application prototyped a number of discharge containers having an inner diameter smaller than the inner diameter of a conventional discharge container, and performed a lighting test. As a result, it was confirmed that desired emission intensity and emission spectral characteristics were obtained, and that the amount of the luminescent substance enclosed could be suppressed.

According to an embodiment of the present invention, in a microwave electrodeless lamp that emits light by receiving microwave energy,
A tubular discharge vessel made of quartz glass;
A rare gas and a luminescent material enclosed in the discharge vessel,
The luminescent material includes zinc and cobalt iodide,
The inner diameter of the discharge vessel is 5.0 to 7.0 mm.

  According to an embodiment of the present invention, in the microwave electrodeless lamp, the pressure of the rare gas in the discharge vessel may be 2.0 to 9.0 torr.

  According to an embodiment of the present invention, in the microwave electrodeless lamp, the luminescent material may include cobalt.

  According to the embodiment of the present invention, in the microwave electrodeless lamp, the zinc encapsulation density is 3.0 to 4.0 μmol / cc, and the cobalt iodide encapsulation density is 4.0 to 10.0 μmol / cc. cc.

According to an embodiment of the present invention, in a light irradiation apparatus having a microwave oscillator, an antenna attached to the microwave oscillator, and an electrodeless lamp that emits light by receiving microwave energy from the antenna,
The electrodeless lamp has a discharge vessel filled with an inert gas and a luminescent material,
The inner diameter of the discharge vessel is 5.0 to 7.0 mm.

  According to an embodiment of the present invention, in the light irradiation device, the luminescent material includes zinc, cobalt iodide, and cobalt alone, and the pressure of the rare gas in the discharge vessel is 2.0 to 9.0 torr. Yes, you can.

  According to the embodiment of the present invention, in the light irradiation device, the zinc filling density is 3.0 to 4.0 μmol / cc, and the cobalt iodide filling density is 4.0 to 10.0 μmol / cc. Yes, you can.

  According to the present invention, as an ultraviolet light source in the UV-A region, it has emission intensity and emission spectral characteristics equivalent to those of a mercury-containing discharge lamp, and further suppresses the amount of luminescent material enclosed and improves startability. There can be provided a mercury-free microwave electrodeless lamp and a light irradiation apparatus using the same.

FIG. 1A is a schematic perspective view showing an example of a light irradiation apparatus using the microwave electrodeless lamp according to the present embodiment. FIG. 1B is a schematic front view of the light irradiation device of FIG. 1A as viewed from the front. FIG. 2 is a diagram illustrating a cross-sectional configuration of the front side inside of the housing of the light irradiation apparatus according to the present embodiment. FIG. 3 is a diagram illustrating an example of an electrodeless lamp according to the present embodiment. FIG. 4 is a diagram illustrating dimensions of an example of the electrodeless lamp according to the present embodiment. FIG. 5 is a diagram for explaining the relationship between the lamp input power obtained by the lighting experiment of the electrodeless lamp conducted by the present inventor and the peak intensity of ultraviolet rays in the UV-A region. FIG. 6 is a diagram for explaining the relationship between the lamp input power obtained by the lighting experiment of the electrodeless lamp conducted by the present inventor and the integrated light quantity of ultraviolet rays in the UV-A region. FIG. 7 is a view for explaining the relationship between the wavelength obtained by the lighting experiment of the electrodeless lamp conducted by the present inventor and the intensity of ultraviolet rays in the UV-A region. FIG. 8 is a diagram for explaining the relationship between the wavelength obtained by the electrodeless lamp lighting experiment conducted by the present inventors and the relative intensities of ultraviolet rays and visible rays. FIG. 9A is a diagram illustrating an example of a front configuration of an ultraviolet ray measurement system implemented by the inventors of the present application. FIG. 9B is a diagram for explaining an example of a planar configuration of an ultraviolet ray measurement system implemented by the inventors of the present application.

  Hereinafter, an electrodeless lamp according to the present invention and a light irradiation apparatus using the same will be described in detail with reference to the accompanying drawings. It should be noted that this embodiment is an exemplification and does not limit the present invention in any way.

  1A and 1B are diagrams illustrating an example of a light irradiation apparatus using a microwave electrodeless lamp according to the present embodiment. FIG. 1A is a perspective view of the light irradiation device 10. FIG. 1B is a schematic front view of the light irradiation device 10 of FIG. 1A as viewed from the front. As shown in the figure, the X axis is set along the lamp axis direction of the light irradiation device 10, the Z axis is set along the light emission direction (arrow direction) from the light irradiation device 10, and the Y axis is set in the direction perpendicular to the XZ plane. .

  The light irradiation device 10 has a rectangular housing 4, and a microwave oscillator 3 (not shown) is provided inside the rear side of the housing 4. The light irradiation device 10 further includes an antenna 8 attached to the microwave oscillator 3, an electrodeless lamp 12 that emits light upon receiving microwave energy from the antenna 8, and a reflection disposed along the axis of the electrodeless lamp 12. It has a mirror 14. A space surrounded by the reflecting mirror 14 forms a microwave cavity 5. The electrodeless lamp 12 is disposed in the microwave cavity 5.

  The light irradiation device 10 further includes a cooling air supply mechanism that cools the electrodeless lamp 12. The cooling air supply mechanism has a cooling air source (not shown) and a cooling air duct 6 (not shown in FIG. 1B) mounted on the upper side of the housing 4.

  A microwave indicates an electromagnetic wave having a wavelength of 1 m to 100 μm and a frequency of 300 MHz to 3 THz, and is the shortest wavelength region among radio waves. Examples of the microwave oscillator 3 include a circuit using a magnetron, a klystron, a traveling wave tube (TWT), a gyrotron, and a Gunn diode. In this embodiment, a magnetron is used as the microwave oscillator. A magnetron is a type of oscillation vacuum tube that generates powerful non-coherent microwaves. In familiar places, magnetrons are used in radar and microwave ovens. In this embodiment, a magnetron used in a microwave oven, preferably a commercial microwave oven, is used. Note that the microwave oven uses a frequency of 2,450 MHz, but this is not due to technical limitations but due to legal restrictions.

  FIG. 2 shows a cross-sectional configuration inside the front side of the housing 4 of the light irradiation apparatus 10 according to the present embodiment. Typically, the reflecting mirror 14 includes an ellipsoidal reflecting mirror for condensing on the irradiated surface, a parabolic reflecting mirror that applies parallel light to the irradiated surface, and the like. Both the ellipsoid and the paraboloid have at least one focal point. In the embodiment of FIG. 2, the reflecting mirror 14 is a saddle-type ellipsoidal reflecting mirror, the electrodeless lamp 12 is a straight tube type, and is arranged so that its central axis is located at the focal point of the ellipsoidal reflecting mirror. Note that the center (center axis) of the electrodeless lamp does not necessarily coincide with the focal position of the reflector, and the central portion of the lamp body is located at the position including the focal point in consideration of the positional error of the lamp. It only has to be arranged.

  A light exit 2 is formed on the front surface of the housing 4 of the reflecting mirror 14, and the light exit is covered with a conductive mesh 16. The conductive mesh 16 is impermeable to microwaves but is transmissive to irradiation light 18 from the microwave cavity, that is, visible light and ultraviolet rays.

  Microwaves generated from the microwave oscillator 3 are radiated through the antenna 8 and supplied to the microwave cavity 5 where a standing wave is formed. Plasma is excited inside the electrodeless lamp 12 disposed in the microwave cavity 5. Visible rays or ultraviolet rays radiated from the plasma are reflected from the reflecting mirror 14 as the irradiation light 18 or directly emitted toward the light exit 2 and pass through the conductive mesh 16 to be irradiated on the irradiated surface. The

  Cooling air 17 from a cooling air source (not shown) is supplied to the microwave cavity 5 through the cooling air duct 6 (FIG. 1A) and through the hole 14 </ b> A of the reflecting mirror 14. The cooling air 17 collides with the outer peripheral surface of the electrodeless lamp 12 and cools the electrodeless lamp 12.

  An example of a straight tube type electrodeless lamp according to the present embodiment will be described with reference to FIG. The electrodeless lamp 12 is a straight tube type having a cylindrical discharge vessel 12A, and has protrusions 12B at both ends thereof. The electrodeless lamp 12 is held in the microwave cavity by engaging the protrusions 12B on both ends of the discharge vessel with the engaging portions on the inner walls on both sides of the casing.

  When the magnetron is oscillated, microwave energy of 2,450 MHz is supplied to the microwave cavity 5 to form a standing wave. The microwave is combined with the discharge vessel 12A of the electrodeless lamp 12 to excite plasma inside. Visible light or ultraviolet light is emitted from the luminescent material.

When the electrodeless lamp 12 is turned on, two plasma regions 13 are formed inside the discharge vessel 12A as indicated by broken lines. The plasma region 13 forms a standing wave having an antinode 131 and nodes 132 on both sides thereof. The wavelength of this standing wave is λ = propagation speed / frequency = 2.99 × 10 ⁸ (m / s) /2.45 GHz≈123 mm. The length in the axial direction of the discharge vessel 12A of the electrodeless lamp is formed substantially equal to the length of one wavelength.

  The portion of the antinode 131 of the standing wave has a relatively high temperature and emits relatively strong light. This is called the high temperature region (hot zone) 12a, 12b. The portion of the standing wave node 132 is relatively cool and emits relatively weak light. This is called a low temperature region (cold zone) 12c, 12d, 12e. In the discharge vessel 12A, the standing wave is formed symmetrically. Therefore, the lowest temperature position in the center is at the center position in the axial direction of the discharge vessel 12A. In the low temperature regions 12c, 12d, and 12e, evaporation of the encapsulated material may be inhibited or reaggregation may occur. Therefore, the temperature distribution in the discharge vessel 12A of the electrodeless lamp 12 becomes non-uniform along the axial direction.

  An example of a straight tube type electrodeless lamp according to the present embodiment will be described with reference to FIG. The electrodeless lamp 12 according to this embodiment includes a cylindrical discharge vessel 12A and protrusions 12B and 12B on both sides. The discharge vessel 12 </ b> A has a cylindrical portion 121. End portions 123 and 123 are formed on both sides of the cylindrical portion. The end portions 123 and 123 are formed in the low temperature regions 12d and 12e on both sides of the discharge vessel, and may be formed in a rotational curved surface shape such as a spherical shape or an elliptical spherical shape.

  The dimension in the axial direction of the electrodeless lamp is L1, the dimension in the axial direction of the discharge vessel 12A is L, and the dimension in the axial direction of the protrusions 12B and 12B is Lt. L1 = L + 2Lt = 150 to 160 mm, L = 130 to 140 mm, and Lt = 8.0 to 9.0 mm. The inner diameter of the cylindrical portion 121 is D, and the outer diameters of the protrusions 12B and 12B are Dt.

  The electrodeless lamp 12 is made of quartz glass. The discharge vessel 12A is formed of a sealed vessel made of quartz glass. The protrusions 12B and 12B are quartz glass rods. The discharge vessel 12A is filled with a starting rare gas or inert gas and a luminescent material.

  The luminescent substance in the electrodeless lamp of the embodiment of the present invention will be described. As described above, in the embodiment of the present invention, zinc, an iron-based element (iron, nickel, cobalt), and a halide of an iron-based element are used as the light-emitting substance. Indium (In), indium iodide (InI), and the like are not used.

  First, zinc will be described. As described above, zinc is known to generate an emission peak at wavelengths of 330 nm and 335 nm in the UV-A region. Furthermore, since zinc has a high vapor pressure, the impedance during lighting can be increased, and microwave energy can be absorbed efficiently. Therefore, the plasma temperature can be raised and the emission intensity of cobalt can be raised. According to the knowledge obtained by an experiment conducted by the inventors of the present application (Japanese Patent Application No. 2014-067228), it has been confirmed that zinc alone is preferable to a halide of zinc. Furthermore, it has been confirmed that the enclosed density of the zinc simple substance is preferably 3.0 to 4.0 μmol / cc. Therefore, also in this embodiment, the enclosure density of zinc simple substance shall be 3.0-4.0 micromol / cc.

Next, iron-based elements (iron, nickel, cobalt) and halides of iron-based elements will be described. According to the knowledge obtained by experiments conducted by the inventors of the present application (Japanese Patent Application No. 2014-067228), when cobalt iodide (CoI ₂ ) is used as a halide of an iron-based element, the emission intensity in the UV-A region is It is confirmed to increase. Furthermore, it is known that the enclosure density of cobalt iodide (CoI ₂ ) is preferably 4.0 to 10.0 μmol / cc. Therefore, also in this embodiment, the enclosure density of cobalt iodide (CoI ₂ ) is 4.0 to 10.0 μmol / cc. Furthermore, it has been confirmed that when cobalt simple substance (Co) is further added to cobalt iodide (CoI ₂ ), the startability is improved and the emission intensity in the UV-A region is increased.

  As described above, the inventor of the present application has desired emission intensity and emission spectral characteristics, and further reduces the inner diameter of the discharge vessel and reduces the volume of the discharge vessel in order to reduce the amount of luminescent material enclosed. Thought to do. The inventor of the present application prototyped a number of discharge vessels having different discharge vessel inner diameters and performed a lighting test. As a result, it was confirmed that desired emission intensity and emission spectral characteristics could be obtained even if the inner diameter of the discharge vessel was reduced. That is, it was confirmed that the desired amount of light emission and emission spectral characteristics were achieved, and at the same time, the amount of the light emitting substance enclosed could be suppressed.

  Below, the experiment which the inventor of this application performed is demonstrated. Table 1 shows the specifications and luminescent materials of the discharge containers of Experimental Examples 1 to 9 that were experimentally manufactured by the inventors of the present application. In this experiment, a straight tube type electrodeless lamp shown in FIG. 4 was used. First, the shape and dimensions of the discharge vessel 12A of the electrodeless lamp used in the experiment will be described. The dimensions of the discharge vessel are as follows. L1 = L + 2Lt = 155 mm, L = 138 mm, Lt = 8.5 mm, and Dt = 3 mm. As shown in Table 1, the inner diameter of the discharge vessel 12A is D = 4.0 to 20.0 mm, and the inner volume of the discharge vessel 12A is 1.69 to 41.0 cc. The thickness of the discharge vessel 12A is 1 to 2 mm.

  The inner diameter of the discharge vessel of Experimental Example 3 is D = 9.0 mm and the volume is 8.78 cc, which is the same as the inner diameter and volume of the discharge vessel that is normally used. Therefore, Experimental Example 3 is hereinafter referred to as a comparative example. In Experimental Examples 1 and 2, the inner diameter of the discharge vessel is D> 9.0 mm, which is larger than the inner diameter of the discharge vessel of the comparative example (Experimental Example 3). In Experimental Examples 4 to 9, the inner diameter of the discharge container is D <9.0 mm, which is smaller than the inner diameter of the discharge container of the comparative example (Experimental Example 3).

The luminescent materials of Experimental Examples 1 to 8 are simple cobalt (Co), cobalt iodide (CoI ₂ ), and zinc (Zn). The luminescent materials of Experimental Example 9 are cobalt iodide (CoI ₂ ) and zinc (Zn). In Experimental Examples 1 to 8, the amount and density of each luminescent substance were set so that the total density of the luminescent substance was about 30 μmol / cc. In Experimental Examples 1 to 8, the enclosure density of simple cobalt (Co) is 19.9 to 22.0 μmol / cc, the enclosure density of cobalt iodide (CoI ₂ ) is 5.7 to 6.5 μmol / cc, and zinc is enclosed. The density is 3.0 to 3.8 μmol / cc. In Experimental Example 9, the amount of enclosed cobalt (Co) was zero, the enclosed density of cobalt iodide (CoI ₂ ) was 5.91 μmol / cc, and the enclosed density of zinc was 3.50 μmol / cc. Argon was used as a starting rare gas sealed in the discharge vessel 12A.

As described above, the inventors of the present application aim to realize a mercury-free electrodeless lamp having emission intensity and emission spectral characteristics equivalent to a mercury-containing discharge lamp as an ultraviolet light source in the UV-A region. It was. In the mercury-containing electrodeless discharge lamp, for example, when the lamp input power is 1.8 kW, the peak intensity of ultraviolet rays in the UV-A region is 1320 mW / cm ² and the integrated light quantity is 620 mJ / cm ² . Therefore, it was aimed that the peak intensity of ultraviolet rays in the UV-A region exceeds at least 1254 mW / cm ² (95%), preferably 1280 mW / cm ² (97%). Moreover, it aimed at the integrated light quantity of the ultraviolet-ray of a UV-A area | region exceeding 620 mJ / cm < ² >. In addition, the value measured with the ultraviolet-ray measuring apparatus which drive | works at the conveyance speed of 6 m / min is used for the integrated light quantity of the ultraviolet-ray of a UV-A area | region. A method for measuring the cumulative amount of ultraviolet light will be described later.

  A first experiment conducted by the inventor of the present application will be described. In the first experiment, the argon pressure was set to 5.0 torr (constant), the lamp input power was changed, and the ultraviolet light emission intensity in the UV-A region and the spectral characteristics were measured. When the lamp input power was 1.8 kW, the case where the peak intensity of ultraviolet rays and the integrated light quantity in the UV-A region exceeded the target values was regarded as acceptable. According to the first experiment, in Experimental Examples 3, 4 to 7, and 9, it was confirmed that the peak intensity of ultraviolet rays and the integrated light amount in the UV-A region exceeded the target values. However, in Experimental Example 3 (Comparative Example), the inner diameter of the discharge vessel is D = 9.0 mm, which is the same as the inner diameter of a normal discharge vessel. Therefore, the goal of the present invention, which is to reduce the amount of encapsulated luminescent material, cannot be achieved. Therefore, as shown in the rightmost column of Table 1, Experimental Examples 4 to 7 and 9 are accepted. That is, it was confirmed that desired emission intensity and emission spectral characteristics can be obtained with respect to ultraviolet rays in the UV-A region by setting the inner diameter D of the discharge vessel to 5.0 to 7.0 mm.

The result of the first experiment will be described in more detail with reference to FIG. FIG. 5 shows the relationship between the lamp input power and the peak intensity of ultraviolet rays in the UV-A region. The horizontal axis represents the lamp input power (unit: W), and the vertical axis represents the peak intensity of ultraviolet rays in the UV-A region (unit: mW / cm ² ). FIG. 5 shows the results of Experimental Example 3 (Comparative Example) and Experimental Examples 4, 5, and 9 determined to be acceptable. It can be seen that when the lamp input power is increased, the peak intensity of ultraviolet rays in the UV-A region increases substantially linearly. As described above, when the lamp input power is 1.8 kW, the peak intensity of ultraviolet rays in the UV-A region is 1254 mW / cm ² (95%) and 1280 mW / cm ² (97%), which are target values. It turns out that it is over. A method for measuring the peak intensity of ultraviolet rays will be described later.

The result of the first experiment will be described in more detail with reference to FIG. FIG. 6 shows the relationship between the lamp input power and the integrated light quantity of ultraviolet rays in the UV-A region. The horizontal axis represents lamp input power (unit: W), and the vertical axis represents the cumulative amount of ultraviolet light (unit: mJ / cm ² ) in the UV-A region. FIG. 6 shows the results of Experimental Example 3 (Comparative Example) and Experimental Examples 4, 5, and 9 determined to be acceptable. It can be seen that when the lamp input power is increased, the cumulative amount of ultraviolet light in the UV-A region increases substantially linearly. It can be seen that when the argon pressure is 5.0 torr and the lamp input power is 1.8 kW, the total amount of ultraviolet rays in the UV-A region exceeds the target value of 620 mJ / cm ² . A method for measuring the cumulative amount of ultraviolet light will be described later.

Table 2 shows the peak intensity (unit) of UV in the UV-A region when the lamp input is 1.8 kW for Experimental Example 3 (Comparative Example) and Experimental Examples 4, 5, and 9 determined to be acceptable. : MW / cm ² ) and integrated light quantity (unit: mJ / cm ² ) are extracted and summarized in a table. In both cases, the peak intensity and integrated light intensity of the ultraviolet rays in the UV-A region exceed the target values of 1254 mW / cm ² (95%) and 1280 mW / cm ² (97%). Moreover, it exceeds 620 mJ / cm ² , which is the target value of the cumulative amount of ultraviolet light in the UV-A region.

The result of the first experiment will be described in more detail with reference to FIG. FIG. 7 shows the relationship between the wavelength and the spectral intensity of ultraviolet rays in the UV-A region. The horizontal axis represents wavelength (unit: nm), and the vertical axis represents the spectral intensity (unit: μW / cm ² / nm) of ultraviolet rays in the UV-A region. FIG. 7 shows the UV-A region (wavelength 315 to 400 nm) of Experimental Example 3 (Comparative Example) and Experimental Example 5 determined to be acceptable when the argon pressure is 5.0 torr and the lamp input power is 1.8 kW. ) Spectral characteristics. It can be seen that in the UV-A region (wavelength 315 to 400 nm), the emission intensity of Experimental Example 5 is greater than the emission intensity of Experimental Example 3 (Comparative Example).

  The result of the first experiment will be described in more detail with reference to FIG. FIG. 8 shows the relationship between the wavelength and the relative intensity of ultraviolet light and visible light. The horizontal axis represents wavelength (unit: nm), and the vertical axis represents the relative intensity (%) of ultraviolet light and visible light. Here, the relative intensity is the intensity at each wavelength expressed as a 100 fraction, with the intensity value of the emission peak being 100%. FIG. 8 shows the spectral characteristics of Experimental Example 3 (Comparative Example) and Experimental Example 5 determined to be acceptable when the argon pressure is 5.0 torr and the lamp input power is 1.8 kW. In any case, the emission intensity in the UV-A region (wavelength 315 to 400 nm) is larger than the emission intensity in the visible light region (wavelength 380 to 780 nm). Therefore, it can be seen that the electrodeless lamp of this embodiment efficiently emits ultraviolet light in the UV-A region (wavelength 315 to 400 nm). A peak appears in the wavelength region of 465 to 500 nm, and this seems to correspond to the emission peak of zinc at wavelengths of 468 nm, 472 nm, and 481 nm.

The second experiment and the results will be described with reference to Table 3. In the second experiment, startability was observed by changing the pressure of argon. The specifications of the discharge vessel used in this experiment correspond to Experimental Example 5 in Table 1. That is, the inner diameter of the discharge vessel is 6.5 mm, and the luminescent materials are simple cobalt (Co), cobalt iodide (CoI ₂ ), and zinc (Zn). The lamp input power was 1.8 kW (constant). When the argon pressure was 2.0 to 9.0 torr, the startability was good.

The third experiment and the results will be described with reference to Table 4. In the third experiment, the relationship between the inner diameter of the discharge vessel and the startability was measured. Except for Experimental Example 10, it corresponds to Experimental Examples 2, 3, and 5 to 8 in Table 1. The luminescent material of Experimental Example 10 is cobalt simple substance (Co), cobalt iodide (CoI ₂ ), and zinc (Zn) similarly to Experimental Examples 2, 3, and 5 to 8 in Table 1, and the total amount of the luminescent material is The encapsulating amount and the encapsulating density of each luminescent material were set so that the encapsulating density was about 30 μmol / cc. The argon pressure was 5.0 torr and the lamp input power was 1.8 kW (constant). It has been found that the startability is good when the inner diameter of the discharge vessel is 5.0 to 12.0 mm. In the case of Experimental Examples 2 and 3, since the inner diameter of the discharge vessel is 9 mm or more, the target of the present invention, that is, the reduction of the amount of luminescent material enclosed cannot be achieved. Therefore, Experimental Examples 2 and 3 are excluded from the present embodiment of the present invention.

  The fourth experiment and the results will be described with reference to Table 5. In the fourth experiment, the relationship between the inner diameter of the discharge vessel and the splitting and redness of the arc was observed. The inventor of the present application has taken an image of arc splitting and redness. In addition, illustration of a photograph is abbreviate | omitted. In the mercury-free type electrodeless lamp, the increase in lamp input power or the decrease in cooling air volume causes arc splitting and reddening, resulting in a decrease in lamp efficiency. The arc splitting and reddening may be due to the fact that when the plasma temperature rises, the plasma frequency increases and microwave energy cannot enter the plasma. According to an image (not shown) obtained by the fourth experiment, it was found that when the inner diameter of the discharge vessel is reduced, the arc is not easily split and reddened. The circles in Table 5 indicate that arc splitting and redness did not occur, and the x marks indicate that arc splitting and redness occurred. As described above, in the embodiment of the present invention, the inner diameter of the discharge vessel is D = 5.0 to 7.0 mm. Accordingly, arc splitting and reddening are avoided in the embodiment of the present invention.

  With reference to FIG. 9A and FIG. 9B, the example of the measuring method of the peak intensity of an ultraviolet-ray of a UV-A area | region and an integrated light quantity is demonstrated. FIG. 9A shows an example of the front configuration of the measurement system implemented by the inventors of the present application, and FIG. 9B shows an example of the planar configuration. The light irradiation device 10 of the present embodiment is disposed above the conveyor 201, and the ultraviolet ray measuring device 202 is disposed on the conveyor 201. As described with reference to FIG. 2, the light irradiation device 10 includes the housing 4, the reflecting mirror 14, and the electrodeless lamp 12, and further includes the cooling air duct 6.

  The reflecting mirror 14 faces downward, that is, the upper surface of the conveyor 201. The light irradiation device 10 is arranged so that the center axis of the electrodeless lamp 12 is along the width direction of the conveyor 201, that is, orthogonal to the traveling direction of the conveyor 201. The ultraviolet rays from the electrodeless lamp 12 are irradiated directly or through the reflecting mirror 14 downward. The distance Ha between the lower end of the housing 4 and the conveyor 201 is Ha = 63 mm, and the distance between the electrodeless lamp 12 and the ultraviolet ray measuring device 202 is Hb = 105 mm. The conveyor 201 travels at a constant transport speed V (m / min). The conveyance speed was V = 6 m / min. The ultraviolet ray measuring device 202 detects ultraviolet rays when passing under the light irradiation device 10.

The ultraviolet ray measuring device 202 measures the peak value of the intensity of ultraviolet rays in the UV-A region and the integrated value thereof. The intensity of ultraviolet rays is obtained as a graph with the horizontal axis representing time and the vertical axis representing ultraviolet intensity. The peak of the peak of this graph is the peak intensity of ultraviolet rays (unit: mW / cm ² ), and the peak area of this graph represents the integrated light quantity (unit: mJ / cm ² ).

  The findings obtained from experiments conducted by the inventors of the present application will be summarized. The conditions necessary for realizing a mercury-free electrodeless lamp having a light emission intensity and emission spectral characteristics equivalent to those of a mercury-containing discharge lamp as an ultraviolet light source in the UV-A region are as follows.

  (1) In order to ensure the emission intensity and emission spectral characteristics equivalent to those of a mercury-containing type discharge lamp and to reduce the total amount of light-emitting substance sealed, the inner diameter D of the discharge vessel is set to the inner diameter D of the conventional discharge vessel. = 9.0 mm, and more specifically, 5.0 to 7.0 mm.

  (2) Further, the pressure of the gas enclosed in the discharge vessel is set to 2.0 to 9.0 torr.

(3) Zinc (Zn) and cobalt iodide (CoI ₂ ) are used as the light-emitting substance. Further, simple cobalt (Co) may be added.

(4) In order to realize the target emission intensity and emission spectral characteristics, the enclosure density of zinc alone is 3.0 to 4.0 μmol / cc, and the enclosure density of cobalt iodide (CoI ₂ ) is 4.0 to 4.0. 10.0 μmol / cc.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited by these embodiments, and various modifications can be made within the scope of the invention described in the claims. This will be readily appreciated by those skilled in the art.

  In the present invention, a light irradiation apparatus equipped with a microwave electrodeless lamp can be suitably used for, for example, surface hardening treatment of a surface coated with ink, coating, or the like.

DESCRIPTION OF SYMBOLS 2 ... Light emission port, 3 ... Microwave oscillator, 4 ... Housing | casing, 5 ... Microwave cavity, 6 ... Cooling air duct, 8 ... Antenna, 10 ... Light irradiation apparatus, 12 ... Electrodeless lamp, 12A ... Discharge vessel , 12B ... projections, 12a, 12b ... high temperature region (hot zone), 12c, 12d, 12e ... low temperature region (cold zone), 13 ... plasma region, 14 ... reflector, 14A ... hole, 16 ... conductive mesh, DESCRIPTION OF SYMBOLS 17 ... Air for cooling, 18 ... Irradiation light, 121 ... Cylindrical part, 123 ... End part, 131 ... Abdomen, 132 ... Node, 201 ... Conveyor, 202 ... Ultraviolet measuring device

Claims (7)

In microwave electrodeless lamps that emit light upon receiving microwave energy,
A tubular discharge vessel made of quartz glass;
A rare gas and a luminescent material enclosed in the discharge vessel,
The luminescent material includes zinc and cobalt iodide,
A microwave electrodeless lamp having an inner diameter of 5.0 to 7.0 mm. The microwave electrodeless lamp according to claim 1, wherein
A microwave electrodeless lamp, wherein a pressure of a rare gas in the discharge vessel is 2.0 to 9.0 torr. The microwave electrodeless lamp according to claim 1, wherein
The microwave electrodeless lamp, wherein the luminescent material includes cobalt. The microwave electrodeless lamp according to claim 1, wherein
The microwave electrodeless lamp, wherein an enclosure density of the zinc is 3.0 to 4.0 μmol / cc, and an enclosure density of the cobalt iodide is 4.0 to 10.0 μmol / cc. A microwave oscillator,
An antenna that comes with the microwave oscillator,
A light irradiation apparatus comprising the microwave electrodeless lamp according to claim 1 . In the light irradiation apparatus of Claim 5,
The luminescent material includes zinc, cobalt iodide, and cobalt simple substance,
The light irradiation apparatus whose pressure of the noble gas of the said discharge vessel is 2.0-9.0torr. In the light irradiation apparatus of Claim 6,
The light irradiation apparatus, wherein the zinc filling density is 3.0 to 4.0 μmol / cc, and the cobalt iodide filling density is 4.0 to 10.0 μmol / cc.

Images