JP5928848B2 - Light irradiation device and long arc type discharge lamp - Google Patents

Description

  The present invention relates to a light irradiation apparatus having an ultraviolet light source and a long arc type discharge lamp used therein.

  Conventionally, in the printing industry and the electronics industry, as an ultraviolet light source for photochemical reaction equipment used for drying ink and paint, curing resin, or for exposing a liquid crystal substrate for a semiconductor substrate or a liquid crystal display. A long arc type discharge lamp such as a metal halide lamp is used as an ultraviolet light source of an exposure apparatus to be used.

The structure of a light irradiation apparatus using such a long arc type discharge lamp is known, for example, in Japanese Patent Laid-Open No. 2008-130302 (Patent Document 1), and the structure is shown in FIG.
The light irradiation device 20 is provided with a long arc type discharge lamp 1 in a housing 21, and is provided with a bowl-shaped reflection mirror 22 surrounding the discharge lamp 1. A reflection surface 23 made of is formed.
The top opening 22 a of the reflection mirror 22 is disposed corresponding to the cooling air exhaust port 24 formed in the housing 21. The reflection mirror 22 is openable and closable, and the front opening 22b is opened in the steady lighting mode in which the processing object is irradiated with ultraviolet rays. In the standby lighting mode such as replacement of the processing object, the reflection mirror 22 is opened. Rotates to close the front opening 22b. In the standby lighting mode, the input power to the lamp is reduced from the viewpoint of power saving.
At the time of steady lighting shown in FIG. 5, cooling air flows from below the reflection mirror 22, passes around the lamp 1, cools it, and flows out from the top opening 22 a through the exhaust port 24.

A long arc type discharge lamp 1 used in such a light irradiation device 20 is shown in FIGS.
Sealing portions 3 and 3 are formed at both ends of the arc tube 2 of the long arc type discharge lamp 1, and a pair of electrodes 4 and 4 are disposed in the arc tube 2.
Further, a base 5 is attached to the rear end of the sealing portion 3, and when the lamp 1 is incorporated into the light irradiation device, the base 5 is attached to a lamp support (not shown).
A reflective film 10 is formed on the upper surface of the arc tube 2 over substantially the entire area of the light emission length, and reflects upward light in the arc tube 2 to irradiate the processing object below.
As the long arc type discharge lamp 1 having the above-described configuration, for example, a metal halide lamp in which a metal such as mercury, iron, thallium or the like is enclosed in the arc tube 2 is used in order to radiate ultraviolet rays satisfactorily.

By the way, as the reflective film 10 formed on the upper surface of the arc tube 2, as shown in FIG. 7, ceramic-based spherical particles 11 made of silica (SiO ₂ ) or alumina (Al ₂ O ₃ ) are used. It was.
However, in this spherical particle shape, as shown in FIG. 7 (B), the light that has entered the particle is diffusely reflected inside the particle, so that the reflected light having a large reflection angle is processed on the irradiated surface, that is, on the lower side. There was a problem that a large amount of light diffused without reaching the object, resulting in a loss.

JP 2008-130302 A

In view of the above-described problems of the prior art, the present invention includes a long arc type discharge lamp disposed in a housing, and a bowl-shaped reflection mirror disposed behind the discharge lamp, the discharge lamp having Is a light irradiating apparatus in which a strip-shaped reflective film is formed on the outer surface of the arc tube corresponding to the cooling air exhaust port formed in the housing over substantially the entire emission length, and the light reflected by the reflective film is Among them, a structure is provided in which the reflected light directed toward the processed material below the lamp is increased to increase the illuminance so that efficient processing can be performed.
In addition, in the long arc type discharge lamp used in the light irradiation device, a structure is provided in which the reflected light can be effectively directed to the processing object below by the reflective film formed on the outer surface thereof. is there.

In order to solve the above-mentioned problems, the light irradiation apparatus according to the present invention is characterized in that the reflective film formed on the arc tube of the long arc discharge lamp is formed by laminating scaly ceramic particles. .
The scaly ceramic particles forming the reflective film are either silica (SiO ₂ ) or alumina (Al ₂ O ₃ ), or a combination thereof.
The average diameter of the scale-like ceramic particles is larger than the wavelength of the emitted light of the long arc discharge lamp.
Moreover, in the arc tube and the long arc type discharge lamp in which a strip-shaped reflective film is formed over a substantially entire region of the light emission length on a part of the outer surface of the arc tube, the reflective film is composed of scaly ceramic particles. It is characterized by being laminated.
The average diameter of the scaly ceramic particles forming the reflection film of the long arc type discharge lamp is larger than the wavelength of the emitted light of the discharge lamp.

According to the light irradiation device of the present invention, since the reflection film of the long arc type discharge lamp is formed by laminating scale-like ceramic particles, the light reaching the reflection film from the inside of the lamp arc tube is irregularly reflected. There is almost no and the component which goes to an irradiation surface direction increases, and the illumination intensity in a processed material rises markedly.
Moreover, since the average diameter of the scale-like ceramic particles is larger than the wavelength of the light from the lamp, a reflective film having high regular reflection can be obtained.

Sectional view (A) of a main part of a long arc type discharge lamp used in the light irradiation apparatus of the present invention, and a schematic view of scale-like ceramic particles (B) Enlarged view of the reflective film Outline diagram of the experiment to prove the effect Graph of experimental results showing effects Schematic diagram of light irradiation device Sectional view (A) and transverse section (B) of a conventional long arc type discharge lamp Sectional view (A) and enlarged view (B) showing a conventional reflective film

FIG. 1 is a cross-sectional view showing a reflective film which is a main part of a short arc type discharge lamp used in the light irradiation apparatus of the present invention. The reflective film 10 is made of ceramic particles 12 such as silica (SiO ₂ ) or alumina (Al ₂ O ₃ ), and the shape thereof is a scaly shape.
An example of the scale-like shape is shown in FIG. 1B, and the average diameter D of the planar portion is represented by (major axis + minor axis) / 2, and preferably D = 0.5 to 10 μm. It is. The thickness T is preferably 0.001 to 0.05 μm, and the aspect ratio is preferably D / T = 10 or more.

  If the thickness T of the particles is in the above range, a dense film is formed. Therefore, when the particle thickness T is provided as a reflective film on the outer surface of the arc tube, it becomes a gas barrier layer that suppresses intrusion of gas from the outside. In addition, since the upper part of the arc tube is hot when the lamp is lit, moisture adsorbed on the arc tube diffuses inside the arc tube, and if it enters the discharge space, it may cause deterioration of lighting performance or melting of the tungsten electrode. However, since a dense film is formed, moisture is adsorbed on the surface of the reflective film, and moisture can be prevented from entering the bulb from the outer surface of the arc tube.

In addition, when the average diameter D is smaller than the wavelength of the light, the incident light exhibits the property of Rayleigh scattering in which the light is scattered almost isotropically. Therefore, even if the shape of the particles is a scale shape, the reflection is highly specular. Unable to get characteristics. In order to enhance regular reflection, it is preferable that the average diameter D is a scale shape longer than the wavelength of light. For example, for light having a wavelength of 365 nm, the average diameter D may be 500 nm or more.
Further, the shape of the particles preferably has a ratio of the thickness T to the average diameter D (aspect ratio) of 10: 1 or more.

The thickness of the reflective film 10 made of such scaly ceramic particles 12 is preferably 20 μm or more. When the thickness of the reflective film is 20 μm or more and the thickness t of the scale-like ceramic particles is 0.001 to 0.05 μm, about 1000 boundary surfaces of the ceramic particles are present in the reflective film. Since light reflection occurs on the surface (boundary surface) of each scaly ceramic particle, a sufficient reflectance can be ensured.
As described above, if the thickness of the reflective film is 20 μm or more, it is possible to achieve an increase in illuminance suitable for the present invention. Since cracks may occur, for example, the thickness is preferably 200 μm or less.

Hereinafter, a method for producing a reflective film made of scale-like silica particles will be described.
There are a number of methods for producing ceramic particles such as silica used as a reflective film, but taking a chemical synthesis method (wet method) as an example, a ceramic sol in which nano-level ceramic fine particles are dispersed is used. Ceramic particles are aggregated by controlling the concentration and temperature to produce ceramic particles with a large particle size. The particle shape can be controlled by changing the conditions at the time of aggregation, and conventionally used spherical ceramic particles and the scaly ceramic particles of the present invention can be produced according to the purpose.
Similarly, when a silica sol in which nano-level ceramic fine particles are dispersed in a liquid is thinly spread and sintered, the ceramic fine particles are bonded to each other to form a ceramic thin film such as a vapor deposition film. The flaky ceramic particles can also be obtained by grinding this thin film.

A silica slurry can be obtained by dispersing the flaky ceramic (for example, flaky silica) particles thus produced in water.
Silica slurry is applied to the arc tube part that needs to be reflected by various application methods such as dipping and spraying, and slowly dried, so that it is laminated almost parallel to the arc tube surface as shown in FIG. A scaly silica film can be formed.
As a result, as shown in FIG. 2, the light from the arc tube is not diffusely reflected, and almost all of the light is regularly reflected to form a reflective film 10 having high regular reflection toward the irradiated surface (processed object). Can do.

Hereinafter, experiments were conducted to verify the effects of the present invention.
<Lamp specification>
Arc tube: inner diameter 22 mm, outer diameter 26 mm, light emission length (distance between electrodes) 250 mm
Inclusion material: 58 mg of mercury, 2.5 mg of mercury iodide, 1 kPa of argon
Reflective film: width 10 mm, thickness 50 μm, length 250 mm
Materials: scale-like silica fine particles (present invention), spherical silica fine particles (conventional example)

Furthermore, a comparative example lamp without a reflective film was also prepared.
These lamps are lit at 2000 W under natural air cooling, and as shown in FIG. 3, an irradiation surface (area) is installed at a position 170 mm from the outer surface of the lamp, which is the lower surface opposite to the reflective film 10. The illuminance at each point in the orthogonal direction (Y axis) was measured. The illuminance meter used UIT-250 and S365.

The result is shown in FIG. Compared to the comparative lamp without a reflective film (□), the conventional reflective film lamp (◇) coated with spherical silica particles as a reflective film has an integrated illuminance of 1.15 times in the irradiation area (86 mm width). I understand.
On the other hand, in the reflective film lamp (Δ) of the present invention in which scaly silica fine particles are applied as a reflective film, the integrated illuminance in the irradiation area (86 mm width) is 1.21 times. In this way, by using the scaly silica particles as a reflective film, the illuminance of the irradiation area directly under the arc tube is particularly increased compared to the conventional reflective film lamp, and the reflected light escaping outside the irradiation area is reduced and irradiation is performed. It was confirmed that the light was focused on the area.

  As described above, in the present invention, since the reflective film on the outer surface of the arc tube of the long arc type discharge lamp is formed of scale-like ceramic particles, the light from the arc tube is regularly reflected without being irregularly reflected. There is an effect that it is possible to irradiate the processed object with light having high illuminance.

DESCRIPTION OF SYMBOLS 1 Long arc type discharge lamp 2 Arc tube 3 Sealing part 4 Electrode 5 Base 10 Reflective film 11 Spherical ceramic particle 12 Scale-like ceramic particle 20 Light irradiation apparatus 22 Reflection mirror 22a Top part opening 22b Front opening 23 Reflecting surface 24 Cooling wind exhaust port

Claims (3)

A housing, a long arc type discharge lamp disposed in the housing, and a bowl-shaped reflecting mirror disposed behind the discharge lamp, wherein the discharge lamp has cooling air formed in the housing. In the light irradiation device in which a strip-shaped reflective film is formed over substantially the entire emission length on the outer surface of the arc tube corresponding to the exhaust port,
The reflection film is formed by laminating scale-like ceramic particles, and an average diameter of the ceramic particles is larger than a wavelength of light emitted from the discharge lamp . The light irradiation apparatus according to claim 1, wherein the scale-like ceramic particles forming the reflection film are either silica (SiO ₂ ) or alumina (Al ₂ O ₃ ), or a combination thereof. . In a long arc type discharge lamp in which a band-shaped reflective film is formed over a substantially entire region of the light emission length on a part of the outer surface of the arc tube and the arc tube,
The long-arc discharge lamp is characterized in that the reflective film is formed by laminating scaly ceramic particles, and an average diameter of the ceramic particles is larger than a wavelength of light emitted from the discharge lamp.

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