JPS6326881Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a microwave discharge light source device that utilizes light emission by microwave discharge.

Figure 1 shows a conventionally proposed microwave discharge light source device. In the figure, 1 is a magnetron that generates microwaves, 2 is a magnetron antenna of this magnetron, and 3 is a transmitter that transmits microwaves radiated from this magnetron antenna. 4 is a microwave power feed port 1 at the end of this waveguide.
A cavity wall connected via 2, consisting of a spherical part 5 and a cylindrical part 6 connected to this and having a flange part 10 whose end is bent outward, and made of aluminum or the like. It is. 7 is the cavity wall 4
Attach a presser flange 8 and a presser screw 9 to the flange portion 10 of
A metal mesh plate attached to the cavity wall 4 blocks microwaves but allows light to pass through, and together with the cavity wall 4, constitutes a microwave cavity 11. Reference numeral 13 denotes a spherical electrodeless discharge lamp disposed near the center of the spherical portion 5 of the cavity wall 4, and is made of quartz glass or the like, and contains rare gas such as argon, mercury,
Metals such as iron and halogens such as iodine are enclosed. Reference numeral 14 denotes a protrusion provided on a part of the outer wall of the discharge lamp 13, which is made of a low material such as quartz glass and one end of which is inserted and supported in the discharge lamp support portion 17 provided on the top of the spherical portion 5 of the cavity wall 4. It is fitted into a flared discharge lamp support part 16 formed at the other end of a cylindrical discharge lamp support body 15 made of a lossy dielectric material,
It supports the discharge lamp 13 described above. Reference numeral 18 denotes a lens for condensing the light emitted from the metal mesh plate 7 to the outside onto an irradiated surface (not shown).

In the microwave discharge light source device configured in this way, when the power is turned on, microwaves are generated by the magnetron 1, and the generated microwaves are radiated into the waveguide 3 through the magnetron antenna 2. . The radiated microwaves propagate through the waveguide 3 and are radiated into the microwave cavity 11 through the feed port 12, thereby forming a microwave electromagnetic field within the microwave cavity 11. Due to this microwave electromagnetic field, the rare gas in the discharge lamp 13 is discharged and the inner wall of the discharge lamp 13 is heated, and the mercury, iron, etc. in the discharge lamp 13 are converted into halides and evaporated, and the discharge is caused by the discharge of metal gas. Discharge is the main component, and light with a specific emission spectrum depending on the type of metal encapsulated is emitted. The discharge at this time occurs near the tube wall of the discharge lamp 13. That is, the light emitted from the discharge lamp 13 has a spherical shape. Therefore, if the spherical portion 5 of the cavity wall 4 is made a light reflecting surface, the reflected light will pass through the vicinity of the discharge lamp 13 again since the discharge lamp 13 is located near the center of the spherical portion 5. This reflected light and the direct light from the discharge lamp 13 are radiated outward through the metal mesh plate 7. The light emitted outward is focused by a condensing lens 18 onto a necessary irradiated surface.

In the microwave discharge light source device configured in this way, in order to convert more microwave energy into the discharge energy of the discharge lamp 13, the power supply port 12 is configured as a waveguide when the discharge of the discharge lamp 13 is in a steady state. Microwave electromagnetic field in tube 3 and microwave cavity 11
It is designed to best combine with that inside. However, in designing this, it is necessary to optimally determine the shape and size of the cavity 11 and the shape and size of the power feed port 12, which are difficult to determine by calculation and must be determined by repeated experiments. Therefore, the procedure is quite troublesome. Further, until the discharge in the discharge lamp 13 (hereinafter simply referred to as discharge) reaches a steady state, the coupling state of the microwave electromagnetic field at the power supply port 12 changes, and only in the steady state does it reach the designed coupling state. This change in the coupling state means that the impedance of the cavity 11 changes, which also affects the operation of the magnetron 1. The operation of magnetron 1 is stable from the beginning of discharge until it reaches a steady state, so that microwave power can be extracted as efficiently as possible.
It becomes even more difficult to design the shape and size of the cavity 11 and the power feeding port 12.

This invention was made with the aim of eliminating the above-mentioned conventional drawbacks, and by providing an impedance conversion element in the waveguide 3, the design of the cavity 11 and the feed port 12 was made easier. .

Figure 2 is a sectional view of the main parts of an embodiment of this invention.
A capacitive window 31 is inserted in the middle of a waveguide 3, and the cross section taken along line A-A is as shown in FIG. When such a capacitive window 31 is inserted into the waveguide 3, the impedance (or admittance) of the window can be approximately calculated. In the case of this window, the susceptance can be calculated, the height of the waveguide b, the height of the window d,
If the internal wavelength of the microwave waveguide is λg and the characteristic admittance of the waveguide is Yo, then the susceptance of the window is Y ₀ ·4b/λgloge {cosec(πd/2b)}. On the other hand, the impedance (or admittance) of the cavity 11 can be measured using a slot waveguide or the like. The position and height d of the window for converting this impedance into an impedance that allows the magnetron to operate stably can be determined by calculation. In other words, it is only necessary to appropriately design the shape and size of the cavity 11 and the power supply port 12, measure the impedance, and calculate the window, and there is no need to repeat experiments many times to determine the shape and size. . That is, there is no need to bring the cavity into perfect resonance. The window may be an inductive one as shown in FIG. 4, and in this case as well, the susceptance can be determined by calculation. Furthermore, the impedance conversion element may be a metal rod as shown in FIG. 5 and its sectional view taken along line B--B in FIG. 6, and the susceptance can also be approximately calculated. This rod may be a low-loss dielectric material, and the range of impedance transformation is narrow, but unlike a metal rod, there is a risk of air discharge, whereas a dielectric rod does not.

In the above description, one impedance conversion element is inserted, but if the operation of the magnetron 1 cannot be stabilized with one impedance conversion element, impedance conversion may be performed using a plurality of impedance conversion elements.

As mentioned above, this invention consists of a microwave generator that generates microwaves, a waveguide that transmits the microwaves generated by this microwave generator,
A microwave cavity consisting of a mesh plate that closes an opening in a cavity wall connected to this waveguide via a power supply port, and an electrodeless discharge lamp disposed inside this microwave cavity. The microwave discharge light source device is characterized in that the waveguide is provided with an impedance conversion element, which facilitates the design of the cavity and feed port for stable operation of the magnetron.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of the main part of a conventionally proposed microwave discharge light source device, Fig. 2 is a cross-sectional view of the main part of an embodiment of this invention, and Fig. 3 is a cross-section taken along the line A-A in Fig. 2. 4 is a sectional view showing another embodiment of this invention, FIG. 5 is a sectional view of a main part showing still another embodiment of this invention, and FIG. 6 is a sectional view taken along line B-B in FIG. 5. FIG. In the figure, 1 is a microwave generator, 3 is a waveguide, 4 is a cavity wall, 7 is a mesh plate, 12 is a feed port, 13 is an electrodeless discharge lamp, and 31, 32, and 33 are impedance conversion elements. . In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Scope of claims for utility model registration] (1) A microwave generator that generates microwaves, a waveguide that transmits the microwaves generated by this microwave generator, and a connection to this waveguide via a power supply port. When the discharge of a spherical electrodeless discharge lamp disposed inside the lamp is in a steady state, its impedance is equal to that of the waveguide. A microwave cavity whose impedance deviates from the impedance, and an impedance conversion element disposed within the waveguide to match the impedance of the microwave cavity and the waveguide when the discharge of the electrodeless discharge lamp is in a steady state. Microwave discharge light source device equipped with (2) The microwave discharge photoelectric light source device according to claim 1, wherein the impedance conversion element is a window. (3) The microwave discharge light source device according to claim 1, wherein the impedance conversion element is a metal rod. (4) The microwave discharge light source device according to claim 1, wherein the impedance conversion element is a low-loss dielectric rod.