JPS6121397B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a microwave discharge light source device using microwave discharge.

BACKGROUND ART Recently, light source devices that use high-frequency discharge, particularly microwaves as high-frequency waves, have been attracting attention as light source devices that utilize electric discharge.

In conventional light source devices with electrodes, the life of the lamp was determined by the wear and tear of the electrodes, but in light source devices that use microwaves, the lamp can be made electrodeless, resulting in a longer lamp life. .

Furthermore, since there is no heat loss due to electrodes, and the difference in discharge impedance is small between the initial state and the stable state, it is easy to inject power in the initial state even when impedance matching is performed in the stable state, and the discharge Because the power is concentrated on the lamp tube wall, the time it takes to reach the maximum output is short.

FIG. 1(a) is a longitudinal sectional view showing the configuration of the irradiation part of the microwave discharge light source device invented by the present inventors that takes advantage of these features, and FIG. 1(b) is a front view. . Reference numeral 1 denotes a waveguide that guides microwaves from a magnetron (not shown) through a coupling hole 12 to a cavity resonator 11 . Reference numeral 2 indicates a light reflecting mirror whose inner wall is rotationally symmetrical; 3 indicates a mesh plate forming the front surface of the cavity resonator 11; and 4 indicates a mesh plate 3.
5 and 6 are tightening bolts and nuts that tighten the mesh plate and the holding ring; 7 is a spherical discharge lamp with protrusions on the left and right; 8 is made of a material with low dielectric loss such as a quartz pipe; A holder 9 that receives the protrusion of the discharge lamp and holds the discharge lamp supports the holder 8 by penetrating the wall of the cavity resonator, and has an inner diameter smaller than the value specified by the wavelength of the microwave. The cut-off pipe 10 is a bolt for fixing the holder to the cut-off pipe.

The operation of this device is as follows. Microwaves generated from a magnetron (not shown) propagate within the waveguide 1, pass through the coupling hole 12, and are radiated into the cavity resonator 11, creating a microwave electromagnetic field within the cavity. Form. Due to this microwave electromagnetic field, the gas in the discharge lamp 7 is discharged, the inner wall of the discharge lamp is heated, the metal such as mercury in the tube is evaporated and gasified, and the discharge shifts to a discharge of metal gas. At this time, light with a specific emission spectrum depending on the type of metal is generated, so this can be used as a light source. In order to effectively utilize the light from the discharge lamp 7, the rear surface of the cavity resonator is a light reflecting mirror 2, and the front surface is composed of a metal mesh plate 3 that blocks microwaves but transmits light. to emit light only in the forward direction.

Further, the shape of the reflecting mirror 2 is formed so as to provide a uniform illuminance distribution to the front when the discharge lamp 7 is held at the focal point of the reflecting mirror. Furthermore, the cavity vibrator 11 is designed such that microwave energy is efficiently injected into the discharge lamp 7 when the discharge lamp 7 is held in a predetermined position.

Incidentally, since a discharge lamp needs to be replaced when its life reaches the end or when the emission spectrum needs to be changed, it is desirable to have a structure that can be easily attached and detached and that can be held in a predetermined position.

In the device of this invention, a pair of cut-off pipes 9 protruding to the outside are provided on the wall of the cavity resonator, and a pair of holders 8 made of quartz pipes are inserted into the pipes from the left and right sides, and the discharge lamp 7 is Since it is held so as to receive the left and right protrusions, the axial direction of the cut-off pipe defines the direction in which the discharge lamp 7 is held, and the discharge lamp 7
It is easy to attach and detach while ensuring the positioning of the device.

Further, by moving the holder 7 in and out from the outside to the left and right, the discharge lamp can be adjusted to an optimal position, and then fixed with the fixing bolt 10.

The length of the cut-off pipe needs to be such that the leakage of microwaves from inside the cavity resonator is below a level (1 mW/cm ² ) that does not pose a safety problem.

The free space wavelength of the microwave is λcm, the microwave input is P ₀ watt, and the inner radius of the cut-off pipe is a.
cm, and the relative dielectric constant of the holder is εr, the power density (p) of leakage radio waves is given by the following equation.

p=p ₀ /πa ² eXP(-2α) However, a＜λ√ _r ／3.41 Therefore, to make p＜1mW/cm ² or less And it is sufficient.

For example, P ₀ = 1KW, a = 0.4cm, λ = 12.24cm, ε
When r=4, should be 1.6 cm or more.

Next, another embodiment of the device of the present invention in which the holder can be more easily fixed will be described with reference to FIG.

FIG. 2 shows an enlarged longitudinal sectional view of the support portion of the discharge lamp holder in the device of the present invention. In the figure,
Reference numeral 2 indicates a wall of a cavity resonator which also serves as a reflecting mirror, 8 indicates a discharge lamp holder, 9 indicates a cut-off pipe having a length sufficient to prevent leakage of microwaves, and 13 indicates a wall provided on the outer periphery of the cut-off pipe. The screw groove 14 is a cap that covers the holder protruding from the cut-off pipe and is fixed by screwing into the screw groove.

In the embodiment of the present invention, a quartz pipe is used as the holder, but other materials with less dielectric loss, such as a ceramic pipe, may be used.

As described above, according to the present invention, the present device is provided with a cut-off pipe having an inner diameter and length defined by the microwave input and the wavelength of the microwave that protrudes outward on the wall surface of the cavity resonator, Since the discharge lamp is held by a pipe made of quartz or other material with low dielectric loss inserted from the cut-off pipe, it is possible to easily and reliably replace the discharge lamp and adjust its position, and This has the effect that energy is always efficiently injected into the discharge lamp and that leakage of radio waves can be reduced.

[Brief explanation of the drawing]

FIG. 1(a) is a longitudinal cross-sectional view of the irradiation part of the device of the present invention;
FIG. 1(b) is a front view thereof, and FIG. 2 is another embodiment of the present invention, which is an enlarged sectional view of the support portion of the discharge lamp holder. In the figure, 7 is a discharge lamp, 8 is a discharge lamp holder, and 9
11 is a cut-off pipe, 11 is a cavity resonator, 13 is a screw groove, and 14 is a cap. In the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. A cavity resonator having a cut-off pipe projecting outward from the wall and having an inner radius and length defined by the microwave input and wavelength, a holder inserted into the cut-off pipe. , a microwave discharge light source device comprising a discharge lamp having a protrusion held by this holder. 2 The free space wavelength is λcm, and the relative dielectric constant of the holder is ε
r, when the microwave input is P ₀ watt, the inner radius a and length of the cut-off pipe are The microwave discharge light source device according to claim 1, characterized in that it is formed so as to satisfy the following relationship. 3. The microwave discharge light source device according to claim 1, wherein the holder is made of a material with low dielectric loss, such as a quartz glass pipe. 4. The microwave discharge light source device according to claim 1, characterized in that a threaded groove is provided at the tip of the cut-off pipe, and a cap is provided for screwing the threaded groove.