JP2002245972A - Electric discharge lamp and light irradiation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric discharge lamp to stably discharge electricity at low voltage. SOLUTION: Xenon gas G is sealed in a glass valve 2. An outer electrode 3 along the axial direction of the glass valve 2 is provided on a part in the peripheral direction of the outside of the glass valve 2. A main part 5 of an inner electrode 4 is arranged along the axial direction of the glass valve 2 at a position decentered toward the diametrical direction from a center in the glass valve 2. The main body part 5 of the inner electrode 4 approaches an inner surface of the glass valve 2. Dielectric barrier discharge is generated between the main body part 5 of the inner electrode 4 and the outer electrode 3. It is possible to lower voltage required at the time of irradiating an ultraviolet ray from the xenon gas G by the dielectric barrier discharge. It is possible to stably start the dielectric barrier discharge between the main body part 5 of the inner electrode 4 and the outer electrode 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp provided with a bulb in which a discharge gas is sealed and a light irradiation device provided with the discharge lamp.

[0002]

2. Description of the Related Art Conventionally, a discharge lamp of this type has a cylindrical glass bulb hermetically formed of synthetic quartz glass. At the center of the cross section of the glass bulb, a filamentary internal electrode formed of a tungsten (W) member is provided along the axial direction of the glass bulb. Xenon (Xe) gas as a discharge gas is sealed in the glass bulb at a pressure of about 45 kPa. Further, a wire formed of a nickel (Ni) member is wound around an outer peripheral surface of the glass bulb, and an external electrode is attached.

[0003] Then, by applying a sine wave voltage of 1.5 kV between the internal electrode and the external electrode, discharge is performed in xenon gas by so-called barrier discharge generated through the wall surface of the glass bulb. Xenon excimer emits 172 nm vacuum ultraviolet light. Further, the vacuum ultraviolet light passes through the glass bulb and modifies the surface of the object adjacent to the glass bulb by a photochemical reaction, or cleans the attached organic matter.

[0004]

However, in the above-described discharge lamp, since the barrier discharge concentrates on the metal anchor holding the external electrode, the positive column generated by the barrier discharge is shortened. As a result, the proportion occupied by the cathode fall potential relatively increases, and the surface modification efficiency and the attached organic substance cleaning efficiency decrease.

Further, since the contact portions between the external electrodes and the glass bulb are not equal, the place where the discharge occurs becomes unstable,
There is a problem that the positive column is concentrated and flicker occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a discharge lamp that stably discharges at a low voltage and a light irradiation device including the discharge lamp.

[0007]

According to a first aspect of the present invention, there is provided a discharge lamp, comprising: a cylindrical bulb in which a discharge gas is sealed; and a circumferential outer side of the bulb along an axial direction of the bulb. And an internal electrode in which the main body is disposed eccentrically in the radial direction from the center of the bulb along the axial direction of the bulb.

In this configuration, the external electrode is located at a part of the outer periphery of the cylindrical bulb along the axial direction of the cylindrical bulb in which the discharge gas is sealed. Then
A main portion of the internal electrode is disposed at a position eccentric in a radial direction from a center in the bulb along an axial direction of the bulb. As a result, the main portion of the internal electrode approaches the inner surface of the bulb. As a result, the voltage required when emitting ultraviolet light from the discharge gas in the bulb due to the discharge generated between the main part of the internal electrode and the external electrode decreases,
Discharge can be stably started between the main part of the internal electrode and the external electrode.

According to a second aspect of the present invention, in the discharge lamp of the first aspect, the main portion of the internal electrode includes a plurality of convex portions protruding toward the external electrode at predetermined intervals. .

In this configuration, a plurality of protrusions projecting toward the external electrode at predetermined intervals are provided on the main portion of the internal electrode, so that each of the protrusions of the internal electrode is equal to each other. Close to. As a result, a positive column is likely to be generated between each of the convex portions and the external electrode, so that the current density of the positive column generated between the external electrode and the internal electrode via the bulb decreases. Therefore, the cumulative ionization of the positive column generated between the external electrode and the internal electrode is prevented, so that the lamp efficiency is further improved.

According to a third aspect of the present invention, there is provided the discharge lamp according to the first or second aspect, wherein the main portion of the internal electrode is disposed at a position sandwiching a central axis of the bulb facing the external electrode. It is.

In this configuration, since the main portion of the internal electrode is disposed at a position sandwiching the central axis of the valve facing the external electrode, the distance between the external electrode and the main portion of the internal electrode is increased. As a result, the length of the positive column generated between the external electrode and the internal electrode becomes longer, so that the lamp efficiency is further improved.

According to a fourth aspect of the present invention, there is provided a light irradiating apparatus comprising: a discharge lamp according to any one of the first to third aspects; It is what you have.

[0014] In this configuration, the external electrode is positioned at a part of the outer circumference of the bulb of the discharge lamp housed in the irradiation device main body along the axial direction of the bulb. Next, the main portion of the internal electrode is disposed at a position eccentric in the radial direction from the center in the bulb along the axial direction of the bulb. As a result, the main portion of the internal electrode approaches the inner surface of the bulb. Therefore, the voltage required when emitting ultraviolet light from the discharge gas in the bulb due to the discharge generated between the main part of the internal electrode and the external electrode is reduced, and the voltage between the main part of the internal electrode and the external electrode is reduced. The discharge can be started stably.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIGS. 1A and 1B are longitudinal sectional views showing a discharge lamp, and FIG. 2 is an explanatory view showing a state in which the discharge lamp is turned on.

1 and 2, reference numeral 1 denotes a discharge lamp. This discharge lamp 1 is a dielectric barrier discharge D _3.
Emits light. The discharge lamp 1 is formed airtight from synthetic quartz glass, for example, having an inner diameter of 15 mm.
A cylindrical glass bulb 2 having a length of 600 mm is provided. Xenon (Xe) gas G as a discharge gas is sealed in the glass bulb 2 at a pressure of about 45 kPa.

Here, the discharge lamp 1 is housed in an irradiation device main body of a light irradiation device (not shown). The irradiation device main body irradiates the object to be irradiated with the light emitted from the discharge lamp 1. In addition, the light irradiation device emits ultraviolet light or infrared light in addition to visible light.
A device for decomposing organic substances or curing ink.

An external electrode 3 is attached along a part of the outer surface of the glass bulb 2 in the circumferential direction, for example, at an angle of 45 ° with respect to the entire circumference, along the axial direction of the glass bulb 2. The external electrode 3 is made of aluminum whose surface is coated with a magnesium fluoride (MgF ₂ ) film.
It is formed by closely attaching an (Al) block to the glass bulb 2. The external electrode 3 preferably has an angle range of 90 ° or less with respect to the entire circumference in the circumferential direction of the glass bulb 2.

Further, inside the glass bulb 2, a filament-shaped internal electrode 4 is arranged along the axial direction of the glass bulb 2. The inner electrode 4 is formed in a spiral shape by winding a thin wire formed of a tungsten (W) member having a wire diameter of 0.5 mm along an axial direction of the glass bulb 2 to an outer diameter of 5 mm and a pitch of 2 mm. A main body 5 is provided.

The main body 5 of the internal electrode 4 has non-conductive electrode support members 6a and 6b attached to both ends, and is positioned and fixed in the glass bulb 2. Lead wires 7a and 7b are provided at both ends of the main portion 5 of the internal electrode 4, respectively.
Is provided. These lead wires 7a and 7b protrude outward from the center of both ends in the axial direction of the glass bulb 2.

Further, the main part 5 of the internal electrode 4 is eccentric in the radial direction from the center in the glass bulb 2 along the axial direction of the glass bulb 2 and faces the external electrode 3. It is arranged at a position sandwiching the central axis of the glass bulb 2. Further, each of the portions of the main portion 5 of the internal electrode 4 protruding toward the external electrode becomes a convex portion 8, and a plurality of these convex portions 8 are provided on the main portion 5 of the internal electrode 4 at predetermined intervals.

The main part 5 of the internal electrode 4 has a center in the axial direction which is the center of gravity of the longitudinal section of the main part 5.
It is desirable that the glass bulb 2 is located on the opposite side of the external electrode 3 from the center in the axial direction which is the center of gravity of the longitudinal section. Further, it is more preferable that the side of the main body 5 of the internal electrode 4 on the side of the external electrode be located on the side opposite to the external electrode 3 with respect to the center axis of the glass bulb 2.

The main portion 5 of the internal electrode 4 has a maximum diameter of the spiral portion less than 1/2 of the inner diameter of the glass bulb 2 and a pitch of the spiral portion of 1 mm or more. It is desirable not to exceed the distance from the inner wall surface of the glass bulb 2 on the side facing the main body 5.

Then, one lead wire 7a of the internal electrode 4
An AC power supply 9 is conductively connected between the
I have. This AC power supply 9 connects the external electrode 3 and the internal electrode 4 to each other.
A potential difference is generated between the external electrode 3 and the internal electrode 4.
Between the dielectric barrier discharge D ₃Cause.

Here, the operation of the discharge lamp 1 will be described.

First, a sine wave voltage of 1.5 kV is applied between the internal electrode 4 and the external electrode 3 by the AC power supply 9.

Then, as shown in FIG. 2, the glass bulb 2 of the main part 5 of the internal electrode 4 below the glass bulb 2
The dielectric barrier discharge D ₁ is produced at a position near close to.

Thereafter, the place where the dielectric barrier discharge D ₂ occurs gradually moves toward the external electrode 3, that is, upward, and then moves between the external electrode 3 and the main body 5 of the internal electrode 4. And move on.

The dielectric barrier discharge D ₃ is generated between the portion of the internal electrode 4 closest to the external electrode 3 and the inner wall surface of the glass bulb 2 having the external electrode 3. Moreover, positive column generated by the dielectric barrier discharge D ₃ occurs is a number corresponding to the pitch of the main portion 5 of the inner electrodes 4.

When the number of the positive columns is the same, the more the number is, the more the efficiency is reduced by the cumulative ionization, so that the lamp efficiency is improved.

[0032] However, when the pitch of the main portion 5 of the inner electrode 4 is 1mm or less, same continuous metal rods, i.e. a state protruding portion 8 is not provided, a large positive column centered dielectric barrier discharge D ₃ Moves to the left and right, resulting in a positionally unstable state.

The pitch of the main part 5 of the internal electrode 4 is
If the distance from the inner wall surface of the glass bulb 2 on the side opposite to the main part 5 is exceeded, the site of the electron emission from the main part 5 is not determined, and the flicker similarly occurs to lower the lamp efficiency.

Further, when the external electrode 3 is installed on the glass bulb 2 at a position not opposed to the central axis of the glass bulb 2 or at an angle of 90 ° or more, the main electrode 5 of the internal electrode 4 and the external electrode 3 The distance of the positive column between them becomes shorter. For this reason, the ratio of the cathode drop voltage that makes little contribution to the lamp efficiency increases.

The main portion 5 of the internal electrode 4 is located at a position eccentric in the radial direction from the center in the glass bulb 2.
Is disposed, the main body 5 is connected to the glass bulb 2.
Close to the inner wall surface of. As a result, the main part 5 of the internal electrode 4
Glass bulb 2 due to the discharge generated between
It is possible to reduce the voltage required when emit vacuum ultraviolet rays from xenon gas G of the inner, dielectric barrier discharge D ₃ between the main body portion 5 and the external electrodes 3 of the internal electrodes 4 can be started to stabilize .

Further, by disposing the main portion 5 of the internal electrode 4 at a position sandwiching the central axis of the glass bulb 2 facing the external electrode 3, the distance between the external electrode 3 and the main portion 5 of the internal electrode 4 is increased. Becomes far away. As a result, the length of the positive column generated between the external electrode 3 and the main portion 5 of the internal electrode 4 becomes longer, so that the lamp efficiency can be further improved.

Further, since the main portion 5 of the internal electrode 4 is formed in a spiral shape, an electric field can be concentrated on the main portion 5 until the start of starting. The fluctuation of the positive column caused by the above can be prevented.

Since the plurality of projections 8 of the main portion 5 of the spiral internal electrode 4 are equally close to the external electrode 3, a positive column is formed between each of the projections 8 and the external electrode 3. More likely to occur. For this reason, the current density of the positive column generated between the external electrode 3 and the main part 5 of the internal electrode 4 via the glass bulb 2 can be reduced, and the current density between the external electrode 3 and the main part 5 of the internal electrode 4 can be reduced. Since the cumulative ionization of the positive column caused by the above can be prevented, the lamp efficiency can be further improved.

Further, since the main portion 5 of the internal electrode 4 is formed in a spiral shape, the surface area can be reduced, so that the release of xenon gas G can be prevented. Further, since the shape of the main body portion 5 can be changed, a contact portion that contacts the inner wall surface of the glass bulb 2 at regular intervals along the shape of the glass bulb 2 can be provided, so that stable starting can be performed. Becomes

Further, by making the angle of the external electrode 3 with respect to the entire circumference 90 ° or less, creeping discharge can be prevented, so that discharge efficiency can be improved.

Next, a second embodiment of the present invention will be described with reference to FIGS.

FIGS. 3A and 3B are longitudinal sectional views showing a discharge lamp, and FIG. 4 is a longitudinal sectional view showing a part of the discharge lamp.

In the discharge lamp 1, the coil-shaped main part 5 of the internal electrode 4 is formed in a wave shape that is alternately curved in a direction facing the external electrode 3 and a direction facing the external electrode 3.

At both ends of the main portion 5 of the internal electrode 4, bent portions 11a and 11b for wiring the end of the main portion 5 to the center of the end in the axial direction of the glass bulb 2 are provided, respectively. I have.

Further, in the glass bulb 2, a plurality of electrode support members 12 arranged at equal intervals in the glass bulb 2 are provided. These electrode supports 12 are non-conductive. Further, the main portion 5 of the internal electrode 4 penetrates through the central region of the electrode support 12. For this reason,
These electrode supports 12 are used to hold the internal electrodes 4 inside the glass bulb 2.
Is positioned and fixed.

Here, the operation of the discharge lamp 1 will be described.

First, a voltage is applied between the internal electrode 4 and the external electrode 3 by the AC power supply 9.

Then, a dielectric barrier discharge D ₃ is generated between the external electrode 3 and the main portion 5 of the internal electrode 4.

As a result, the same functions and effects as those of the first embodiment can be obtained.

The main part 5 of the internal electrode 4 is
Of the internal electrode 4
A dielectric barrier discharge D ₃ is formed between a curved apex portion 13 closest to the external electrode 3 in the main body portion 5 and the external electrode _3.
Occurs.

[0051] Thus, since the vertex portion 13 of the internal electrodes 4 are dielectric barrier discharge D ₃ tends to occur, it can be more concentrated the occurrence location of this derivative barrier discharge. Therefore, since it is possible to increase the number of positive column generated by the dielectric barrier discharge D ₃ more reliably, it is possible to further improve the lamp efficiency.

It is to be noted that, even if a fluorescent substance is applied to the inner wall surface of the glass bulb 2 or the main portion 5 of the internal electrode 4, the same operation and effect as those of the above embodiments can be obtained.

[0053]

According to the first aspect of the present invention, since the main portion of the internal electrode is decentered radially from the center of the bulb, the main portion is close to the inner surface of the bulb. The voltage required for generating a discharge between the electrode and the external electrode can be reduced, and this discharge can be started in a stable manner.

According to the discharge lamp of the second aspect, in addition to the effect of the discharge lamp of the first aspect, each of the convex portions of the main portion of the internal electrode is equally close to the external electrode. Since the positive column is easily generated between the external electrode and the external electrode, the current density of the positive column generated between the external electrode and the internal electrode can be reduced, and the cumulative ionization of the positive column can be prevented, so that the lamp efficiency is reduced. Can be further improved.

According to the discharge lamp of the third aspect, in addition to the effect of the discharge lamp of the first or second aspect, the distance between the external electrode and the main part of the internal electrode is long, so that the external electrode and the internal electrode Since the length of the positive column generated between the two can be made longer, the lamp efficiency can be further improved.

According to the light irradiation device of the fourth aspect, the main portion of the internal electrode is decentered radially from the center of the bulb of the discharge lamp housed in the irradiation device main body, so that the main portion of the bulb is Since it is close to the inner surface, the voltage required for generating a discharge between the internal electrode and the external electrode can be reduced, and this discharge can be started stably.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a discharge lamp according to a first embodiment of the present invention. (a) It is a longitudinal cross-sectional view of a discharge lamp. (b) It is a longitudinal cross-sectional view of a discharge lamp.

FIG. 2 is an explanatory diagram showing a situation in which the discharge lamp is turned on.

FIG. 3 is a longitudinal sectional view showing a second embodiment of the present invention. (a) It is a longitudinal cross-sectional view of a discharge lamp. (b) It is a longitudinal cross-sectional view of a discharge lamp.

FIG. 4 is a longitudinal sectional view showing a part of the discharge lamp.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge lamp 2 Glass bulb 3 External electrode 4 Internal electrode 5 Main part 8 Convex part G Xenon gas as discharge gas

Claims (4)

[Claims] 1. A cylindrical valve in which a discharge gas is sealed; an external electrode located in a part of a circumferential direction outside the bulb along an axial direction of the bulb; And an internal electrode having a main portion disposed eccentrically in a radial direction from a center in the bulb. 2. The discharge lamp according to claim 1, wherein the main portion of the internal electrode has a plurality of convex portions projecting toward the external electrode at predetermined intervals. 3. The discharge lamp according to claim 1, wherein the main portion of the internal electrode is disposed at a position sandwiching a central axis of the bulb facing the external electrode. 4. A discharge lamp according to claim 1, further comprising: an irradiation device main body that accommodates the discharge lamp and irradiates an object to be irradiated with light emitted from the discharge lamp. Light irradiation device.