JPH0696609A - Ultraviolet ray radiation source and ultraviolet ray irradiation device - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] To provide a high-power ultraviolet light source and irradiation device that have excellent ultraviolet output characteristics even with high output and high density, and are simpler to cool than conventional ones. [Structure] The irradiation device of the present invention has a bent portion 2a at the center,
A light emitting portion 2 having a U-shaped portion having a flat discharge gas cross section perpendicular to the discharge direction so that a discharge space including a bent portion 2a forms a pair of flat surfaces inside. An electrode that is provided at each end of the discharge space and forms a discharge in the discharge space; an electrode housing portion 29 that is formed to extend from both ends of the light emitting portion 2 and that houses each electrode; The apparatus is provided with a cooling means 26 that is provided in contact with a flat surface and cools the ultraviolet radiation source 1.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet irradiation device for photochemical reaction, for example.

[0002]

2. Description of the Related Art Photochemical reactors using an ultraviolet light source have been adopted in various fields, for example, photo CVD (Chemical).
It is widely used in the field of semiconductor manufacturing such as synthesis of Si thin film by Vapor Deposition method, photo-curing of resist and photo-ashing or photo-cleaning, and its application field is growing significantly.

Also, in the purification and sterilization treatment of water and the sterilization treatment of meat, the research and development of the technique of irradiating ultraviolet rays of short wavelength are rapidly progressing.

In these fields, it is desired to develop a light source for efficiently irradiating short wavelength ultraviolet rays, and therefore, a low pressure mercury ultraviolet discharge lamp is used.

In a low-pressure mercury discharge lamp, electrodes are sealed at both ends of an arc tube made of quartz glass or the like which transmits ultraviolet rays, and a rare gas containing mercury is enclosed in the arc tube to discharge the rare gas mainly containing mercury. By discharging under a low pressure, light in the short wavelength ultraviolet region including the resonance lines 254 nm and 185 nm of mercury is efficiently radiated.

However, in recent years, there has been an increasing demand for improvement in the light output of low-pressure mercury discharge lamps, and practical application of ultra-high-power type lamps is being attempted.

As an ultra-high output type lamp, as shown in FIG. 10, an anode and a cathode are separately provided at both ends of a cylindrical quartz glass arc tube, and an anode at one end and a cathode at the other end are provided. The present inventors have developed a lamp 1 in which the discharge is alternately performed between the cathode and the cathode on the one end side and the anode on the other end side. By disposing the anode and cathode separately from each other in this way, the cathode can be made smaller to reduce heat dissipation, and conversely, the anode can be made larger to increase heat dissipation to reduce the loss of these electrodes. Since the efficiency can be increased, there is an advantage that the luminous efficiency can be improved.

In the figure, reference numeral 2 denotes an arc tube made of quartz glass having a high ultraviolet transmittance, and both ends of the arc tube 2 are sealed by stems 3 and 3 (only one of which is shown).
An anode 4 and a cathode 5 are sealed in the stems 3 and 3, respectively. The anode 4 has a disk shape made of tungsten W or the like, and a cathode 5 made of a tungsten coil filament is arranged on the back of the anode 4. The disk-shaped anode 4 is arranged in front of the cathode 5 on the discharge space side in order to protect the cathode 5 from high-speed electrons that enter the anode 4.

Reference numeral 6 is a lead wire.

The arc tube 2 is filled with a predetermined amount of mercury or amalgam and argon gas for starting.

Such a low-pressure mercury ultraviolet discharge lamp is connected to an AC power source, a half-wave current component is caused to flow between an anode 4 on one end side and a cathode 5 on the other end side to discharge between them, and A reverse half-wave current component is caused to flow between the cathode 5 on one end side and the anode 4 on the other end side to cause discharge between them, and the discharge is alternately repeated in this manner to continue lighting.

Such discharge excites mercury-based vapor in a low-pressure state, and as a result, the mercury resonance line 254 nm or 1
It emits light in the short-wavelength ultraviolet region including 85 nm.

With such a structure, for example, an arc input of 5 W / cm, an inner diameter of the light emitting portion of 24 mm (a cross-sectional area of about 4.5)
cm2) 5 of discharge current 7A (current density of about 1.6A / cm2)
A 00 W UV radiation source is now possible.

However, in the industrial world, higher output and higher density are desired, and as a result of various investigations by the inventors, as a result of the conventional cylindrical arc tube structure shown in FIG. It was found that the self-absorption of the mercury line became more remarkable as the temperature was increased, and that the ultraviolet output decreased rather than the excessively increased input, and that the input density had a limit.

On the other hand, a low pressure mercury discharge lamp generally has about 40
When the light is turned on in the temperature range of 50 to 50 degrees, the luminous efficiency is good. However, if the aim is to increase the output, the temperature of the discharge lamp itself will inevitably increase, and the coldest part temperature cannot be maintained within the above temperature range. Therefore, the electrode housing portion of the discharge lamp is, for example, 40
It is conceivable that the temperature will be controlled by cooling means so that it will be in the coldest part of the temperature. A surface is required, but since the tube cross section is circular, a heat absorption surface having a shape along the outer surface of the discharge lamp is required. When trying to obtain a heat absorbing surface shaped along the outer surface of the discharge lamp,
For example, a cooling block made of metal must be cut out in a shape along the outer surface of the discharge lamp, and it cannot be shared by discharge lamps having different discharge tube diameters, which is very inconvenient.

[0016]

SUMMARY OF THE INVENTION The present invention has been made in view of such a background, and an object thereof is to provide an excellent ultraviolet light output characteristic even if a high output and a high density are achieved by a simple structure. Moreover, it is an object of the present invention to provide a high-power ultraviolet irradiation device that can be easily cooled and can share the components related to cooling.

[0017]

According to a first aspect of the present invention, there is provided a bent portion in the center and a discharge space is formed therein, and the discharge space including the bent portion forms a pair of flat surfaces in the discharge direction. A light emitting portion having a U-shaped portion having a flattened discharge space cross section, electrodes for forming a discharge in the discharge space provided at both ends of the discharge space, and both ends of the light emitting portion. And an electrode accommodating portion that is formed by extending from the electrode accommodating each of the electrodes, and is a UV radiation light source. According to a second aspect of the present invention, there is provided the above-mentioned ultraviolet radiation source, and a cooling means having a flat surface portion, the flat surface portion being in contact with the flat surface of the bent portion and cooling the ultraviolet radiation light source. It is the ultraviolet irradiation device.

According to a third aspect of the present invention, there is provided a box body, an ultraviolet radiation source in which at least a light emitting portion is housed in the box body, and a flat surface portion which is housed in the box body. The flat surface portion is the bent portion. And a cooling means which is provided in contact with the flat surface to cool the ultraviolet radiation source, and the ultraviolet irradiation device.

[0019]

According to the structures of the first and third aspects of the invention, first, considering the light output, the ultraviolet ray output is large in the direction perpendicular to the plane and the other direction is the direction perpendicular to the plane. Compared with this, the UV output is significantly reduced. The reason for this is
It is considered that since the width of the tube in the direction perpendicular to the flat surface is narrow, the absorption of ultraviolet rays by mercury is small and, as a result, the ultraviolet ray output is increased.

Further, since the bent portion also has a flat shape, the bent portion can be efficiently cooled by the cooling means having a simple structure having a flat surface in contact with the flat surface of the bent portion. You can control to an appropriate temperature,
The temperature rise of the electrode itself can be suppressed.

As a result, in the conventional cylindrical arc tube, the limit of the high density of 1.6 to 3 A / cm 2 is
It is possible to provide a high-irradiation irradiator with a large UV output that can handle higher density up to about 8 A / cm2.
Further, when cooling the light source of the present invention, a cooling means having a simple structure having a flat surface may be used, so that the light source of the present invention can be commonly used as the cooling means.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in FIGS.

In FIG. 1, reference numeral 1 denotes a low-pressure mercury discharge lamp serving as a light source. The discharge lamp 1 of this embodiment is made of quartz glass and has a light emitting portion bent in a U shape with a bent portion 2a at the center. The arc tube 2 is made of synthetic quartz glass in this example, and the discharge space including the bent portion 2a is flattened into a substantially rectangular shape having a major axis length of 30 mm and a minor axis length of 15 mm. The shape is different from that of the accommodating portion for the anode and the cathode.

In the arc tube, the lengths of the electrode accommodating portions for accommodating the anode and cathode are set to spaces of about 100 to 300 mm at both ends.

At the end of the arc tube 2, 3 is a stem,
Reference numerals 4 and 5 are electrodes, which are an anode and a cathode, respectively. 6 is a lead line.

The anode 4 is formed of a circular two-layer coil. For example, a tungsten wire having a wire diameter of 1.2 mm is formed into a first layer coil closely wound with an outer diameter of 20 mm and a winding number of 8 turns. A second-layer coil having a number of turns of 3 turns is unwound and formed.

Further, the cathode 5 is arranged such that the filament axis is located closer to the center than on the bulb axis, and the cathode 5 is arranged so as not to project to the discharge space side beyond the front end portion of the anode 4. .

In the present embodiment, such an anode and a cathode are accommodated in a cylindrical electrode accommodating portion 29 having a diameter of 24 mm, and the discharge space portion 10 mm away from the tip of the anode is formed into a flat shape. . The coiled anode 4 is connected to one lead wire 6 connected to the cathode 5.

The arc tube 2 is filled with, for example, 50 mg of mercury and 13 to 267 (Pa) of argon gas. In addition, 7 is a reinforcing member inserted in a straight line portion of the arc tube 1 having a U shape.

The low-pressure mercury discharge lamp 1 is connected to an AC power supply 11 via a lighting circuit device 10, as shown in FIG. The lighting circuit device 10 includes a rectifying / smoothing circuit 12 and a power FET.
Square wave inverter circuit including (field effect transistor)
Equipped with 13. The power FET 13 is provided with variable resistors 14 and 15 for frequency adjustment and current adjustment.

The AC power supply 11 is, for example, a 200 V commercial power supply, and the power supply 11 is connected to the heater transformers 16 and 16 in addition to the rectifying / smoothing circuit 12 and the rectangular wave inverter circuit.

Heater transformers 16 and 16 have cathodes 5 and 5, respectively.
Therefore, the cathodes 5 and 5 are connected to the cathode 5, so that the cathodes 5 and 5 always generate heat and emit thermoelectrons.

FIG. 6 shows a view in which the discharge lamp 1 is incorporated as a device. In the figure, reference numeral 21 is a housing having an open bottom surface for housing the discharge lamp 1, and the housing 21 is a reflector 22 and a radiator. The electric lamp 1, the lamp holder 24, the lamp holder 25, the heat block 26, the heat pipe 27, the fins 28, the fan 40, and the terminal block 30 are housed.

The housing 21 has a mounting flange 32 having screw holes 31 formed around the side surface, a light projecting opening 33 on the lower surface, a locking portion 23 at one end of the light projecting opening 33, and a step portion 34 at the other end. And a lower surface opening cover 35 is arranged from the step portion 34 to the other end side of the housing 21 to form a housing space 36. A heat block having, for example, two through holes 37 formed at one end in the accommodation space 36.
A heat pipe 27 having a plurality of fins 28 attached thereto is inserted through the insertion hole 37.

On the upper surface of the heat block 26, the bent portion 2a of the discharge lamp 1 is placed. For example, a mesh plate 38 is provided on the fins 28, and the mesh plate 38 has a motor (not shown).
A fan 40 of axial flow type is provided, and an exhaust section is provided above the fan 40.
Forming 69. Further, the net plate 38 is provided with a terminal block 30 to which the power supply lead wire 6 of the discharge lamp 1 is connected. The accommodation space 36 includes the heat block 26, the bent portion 2a side and the fan 4
0 and the fin 28 side are partitioned by a partition plate 41 to be spatially separated. In this example, the heat block
Although there is the bent portion 2a above the bent portion 26, the bent portion 2a may be below the heat block 26 because the bent portion planes are located above and below, respectively. By doing so, although the load of the heat block 26 may be directly applied to the bent portion, the light emission of the bent portion can be effectively used. Bend 2a at one end of the discharge lamp
The temperature sensor 201 provided on the contact surface between the heat block 26 and the heat block 26 detects the temperature of the bent portion 2a, and the fan control unit 202 connected to the temperature sensor 201 detects a temperature lower than 45 degrees, for example. When the drive of the fan 40 is lowered and the detected temperature is higher than 45 degrees, for example, the drive of the fan 40 is increased and feedback control is performed so that the coldest portion, which is the position of the temperature sensor 201, is always 45 degrees. In addition,
Feedback control may be performed by detecting the lamp current or the lamp voltage.

The electrode holding portion 29 at the other end of the discharge lamp is a lamp holder.
Although not shown, the lead wire 6 is fixed by the lamp support plate 25b and the lamp support plate 25b, and is connected to the terminal block 30 on the heat block side, which is routed inside the housing.

The reflector 22 is formed by forming an aluminum plate into a rectangular parallelepiped shape whose lower surface is opened. The second reflecting section 42 is formed on the inner side of the housing 21.

Reference numeral 43 denotes a box, which mainly has a processing unit inside.
44, a power supply unit 45, a cooling unit 46, a vertical partition plate 47, and a horizontal partition plate 48 are partitioned to basically block the flow of gas between the respective units. Inside the box body 43, the housing 21, the lifting stud 52 having a spring 51 for fixing the housing 21 by the screw hole 31 of the flange 32 of the housing 21, the irradiation object arrangement portion 53, the blower 54, the above A power supply circuit section 55 containing the above-mentioned circuit for supplying power to the lead wire 6 is housed.

The power supply unit 45 will be described. On the front surface of the power supply unit 45, lighting control of the discharge lamp 1, cooling control, and an irradiation object placement unit 53
An operation panel 56 provided with various switches and a display unit relating to the movement control of the control panel is provided, and an air intake filter 57 and a cooling air intake port 58 of the blower 54 are provided on the surface on the right side of the operation panel to inspect the power supply circuit, It is removable for parts replacement. An air outlet 59 to the processing unit 44 and a circulation unit 61 to the cooling unit 46 are formed in the horizontal partition plate 48, and a blower 54 and a cooling air intake port 58 are formed by ducts 62 and 63, respectively.
It is connected to the.

Next, the cooling unit 46 will be described. Cooling unit 46
An air outlet 64 is provided on the upper surface of the
The fins 28 are cooled by the air taken in from the cooling air intake port 58 and then discharged to the outside of the box body 43. By adjusting the height of the lifting stud 52, the housing 21 can be set at a predetermined position.

Finally, the processing unit 44 will be described. Processing unit
The discharge lamp 1 light emitting unit 2 side of the housing 21 is housed inside the housing 21, and an opening 72 for inserting and removing the drawer 71 is provided in the front surface of the processing unit 44, and the drawer 71 has a handle 73 and a processing unit 44 on the front surface. The portion to be housed inside is, for example, a plate-shaped irradiation object arrangement portion
53, and rollers 74 are provided on both side surfaces of the irradiation object placement portion 53 in the insertion direction, and slide on guides 76 at the tips of a pair of arms 75 mounted in the processing portion 44. Is configured. The irradiation object arrangement portion 53 is formed so that an irradiation object for the purpose of removing organic matters such as a flat plate-shaped liquid crystal panel 99 can be arranged in parallel to the flat surface of the light emitting section 2 of the discharge lamp 1. In addition, as the irradiation object disposing unit, a conveyance type such as a conveyor may be used in addition to a fixed type. Processing unit 44
An ozone discharge port 77 is formed on the upper surface, and the air sent from the blow-out port 59 to the processing unit 44 after being subjected to the ultraviolet ray treatment is discharged.

Although not shown in FIG. 7, a starting circuit is incorporated in the rectangular wave inverter circuit means, and this starting circuit supplies a full-wave rectified voltage of 300 V peak value to the power supply voltage at the time of starting. It is designed to be superimposed and applied to the electrodes. After the lamp is started, the starting circuit detects a voltage drop between the two electrodes of the lamp and operates a relay (not shown) to electrically disconnect the rectangular wave inverter circuit.

The low-pressure mercury discharge lamp 1 in such an embodiment is designed to be lit with a rated input of 800 W and a discharge current of 9.4 amperes. The rectangular wave current given to the lamp is shown in FIG. The waveform diagram of is shown.

A light source according to this embodiment having the above-mentioned structure,
Differences in increasing the output of the ultraviolet radiation light source represented by FIG. 10 having the conventional structure will be described.

FIG. 9 shows the output of ultraviolet rays (254 nm) when the current density of the discharge current is increased, as compared with that of the conventional light source.
It is represented by the relative intensity when the ultraviolet ray output at A is 100.

In the light source according to the present invention, the plane including the long axis of the flat portion of the discharge space is made horizontal, and the intensity of 254 nm of the lamp at the same distance as the conventional light source is measured along the roadside.

As is apparent from FIG. 5, in the prior art, the ultraviolet light output decreases when the current density exceeds about 2.0 A / cm2, whereas the lamp according to the present invention increases to 8 A / cm2 without any decrease. To do.

Specifically, when the value is increased to 20 A from the value of the conventional structure light source at 7 A, the conventional light source has about 60 A.
%, The ultraviolet output of about 200% could be obtained in the present invention.

Regarding this difference, although estimated, the following can be considered. In a cylindrical arc tube, the shape of discharge is cylindrical, and as the current density increases, self-absorption of the Hg line increases, and when the current density is increased, the output of ultraviolet rays, especially short wavelength, decreases. On the other hand, by making the shape of discharge flat as in this example, the mercury vapor layer on the short axis side becomes thin, so self-absorption of ultraviolet rays by mercury is suppressed, and even if the current density is increased, It is considered that the decrease is suppressed and the UV output increases as the input increases.

Here, since the electrodes are arranged on the side of the gap formed by the light emitting portion 2, the center of the discharge cross section perpendicular to the discharge direction is on the side of the gap, and the irradiation target corresponding to the gap is irradiated. The amount of ultraviolet rays generated is greater than in the past, and since the positional relationship is parallel to the entire irradiated object, more uniform irradiation is possible.

On the other hand, the lamp having the conventional structure and the same current value of 800 W had a rate maintaining ratio of 50% or less at 1000 H, in which the luminous flux did not decrease. Further, regardless of the present invention, a lamp in which the discharge space and the electrode absorption portion are also flat inevitably has a small anode structure or is processed into a flat shape, and electrode scattering also adheres to the discharge space portion. Yes, maintenance rate is 50% at 1000H
Below.

An ultraviolet irradiation device using this lamp is shown in FIG.
As mentioned in the measurement of 1., setting the work surface almost parallel to the plane including the long axis of the flat part and placing the irradiated object or moving the irradiated object gives the highest ultraviolet output. Target,
The processing width is set to about the length of the discharge space processed into a flat shape in the region where the ultraviolet light output is the highest and the ultraviolet light changes little during the life.

As described above, the light source and the irradiation device of the present invention can greatly increase the ultraviolet ray output even when the density is increased, and the compact and high output ultraviolet ray application which is desired in the industrial field of ultraviolet ray application. It enables the device.

In the embodiment, the case where only the discharge space portion is formed into a flat shape has been described.
A flat shape having a shorter diameter than the discharge space may be used, and the shape is not limited to the shape described in the embodiment.

[0055]

According to the structures of the first and third aspects of the invention, first, considering the light output, the ultraviolet ray output is large in the direction perpendicular to the plane and the other direction is the direction perpendicular to the plane. Compared with this, the UV output is significantly reduced. The reason for this is
It is considered that since the width of the tube in the direction perpendicular to the flat surface is narrow, the absorption of ultraviolet rays by mercury is small and, as a result, the ultraviolet ray output is increased.

Further, since the electrode accommodating portion also has a flat shape, the bent portion can be efficiently cooled by the cooling means having a simple structure having a flat surface in contact with the flat surface of the bent portion, and as a result, the coldest portion can be cooled. Can be controlled to an appropriate temperature.

As a result, the conventional cylindrical arc tube, which had a limit of high density of 1.6 to 3 A / cm 2,
It is possible to provide a device that can handle a high density of about 8 A / cm2 or more and that has a large output of ultraviolet rays. Further, when cooling the light source of the present invention, a cooling means having a simple structure having a flat surface may be used, so that the light source of the present invention can be commonly used as the cooling means.

[Brief description of drawings]

FIG. 1 is a sectional view showing FIG. 4 along AA.

FIG. 2 is a plan view showing a low pressure mercury discharge lamp according to an embodiment of the inventions of claims 1 and 2;

FIG. 3 is a side view showing a low pressure mercury discharge lamp according to an embodiment of the inventions of claims 1 and 2.

FIG. 4 is a low-side view showing an embodiment of the invention of claims 1 and 2 and showing a part of the irradiation device as seen through.

FIG. 5 is a sectional view showing FIG. 1 along BB.

FIG. 6 is a partial perspective view showing an embodiment of the invention of claims 1 and 2 and showing an irradiation device composed of a box body in a partially cutaway view.

FIG. 7 is a configuration diagram showing a low pressure mercury discharge lamp and a lighting circuit thereof according to an embodiment of the inventions of claims 1 and 2.

FIG. 8 is a waveform diagram of a rectangular wave showing a current applied to a lamp.

FIG. 9 is a diagram showing a difference in ultraviolet output difference between the present invention and a conventional structure lamp when the density is increased.

FIG. 10 is a configuration diagram showing a conventional low-pressure mercury ultraviolet discharge lamp.

[Explanation of symbols]

1 ... Light source, 2 ... Light emitting part, 4 ... Coil type anode, 5 ...
Cathode, 2a ... bent, 26 ... cooling means, 29 ... electrode housing,

Claims (3)

[Claims] 1. A cross section of the discharge space perpendicular to the discharge direction is flat so that a discharge space is formed in the interior thereof with a bent portion in the center, and the discharge space including the bent portion forms a pair of flat surfaces. A light emitting portion having a U-shaped portion, and electrodes formed at both ends of the discharge space to form a discharge in the discharge space; formed by extending from both ends of the light emitting portion, An ultraviolet radiation source, comprising: an electrode accommodating portion that accommodates an electrode. 2. A cross section of the discharge space perpendicular to the discharge direction is flat so as to have a bent portion in the center and form a discharge space inside, and the discharge space including the bent portion forms a pair of flat surfaces. A U-shaped light emitting portion; electrodes provided at both ends of the discharge space to form a discharge in the discharge space; formed to extend from both ends of the light emitting portion and accommodate the electrodes. And a cooling means for cooling the ultraviolet radiation light source, the ultraviolet radiation light source having an electrode accommodating portion; and a flat surface portion, the flat surface portion being in contact with the flat surface of the bent portion. Characteristic UV irradiation device. 3. A box body, a discharge space which has a bent portion in the center thereof, forms a discharge space inside, and is perpendicular to the discharge direction so that the discharge space including the bent portion forms a pair of flat surfaces. A light emitting portion having a U-shape with a flat cross section; electrodes provided at both ends of the discharge space for forming a discharge in the discharge space; formed by extending from both ends of the light emitting portion, An ultraviolet ray light source in which at least the light emitting portion is accommodated in the box body, and a flat portion which is accommodated in the box body. An ultraviolet irradiation device, comprising: a cooling unit which is provided in contact with a flat surface and cools the ultraviolet radiation source.