JPH0217917B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a microwave discharge light source device, particularly to an improvement of a waveguide for propagating microwaves.

[Conventional technology]

FIG. 3 is a cross-sectional view of a conventional microwave discharge light source device disclosed in, for example, Japanese Utility Model Application Publication No. 58-192458. In the figure, 1 is a magnetron serving as an oscillator that oscillates microwaves, 2 is a magnetron antenna, 3 is a waveguide having a ventilation hole 3a through which microwaves propagate, 4 is a microwave cavity wall, and 5 is a double metal mesh plate 5a, 5b spaced apart that reflects microwaves but transmits light. The cavity wall 4 and the light transmitting member 5 constitute a microwave cavity 6. 7 is waveguide 3
8 is an electrodeless discharge lamp placed in the microwave cavity 6, 9 is a fan for cooling the magnetron 1 and the lamp 8, and 10 is a housing for the whole. It is a casing that allows

The conventional microwave discharge light source device is configured as described above, and the microwave oscillated from the magnetron 1 propagates through the waveguide 3 from the antenna 2, is radiated from the feed port 7 into the microwave cavity 6, and is emitted from the microwave. Forms a wave electromagnetic field. Thereby, the lamp 8 absorbs energy from the microwave electromagnetic field and discharges and emits light. This light is emitted to the outside directly or reflected by the cavity wall 4 and passed through the metal mesh plates 5a and 5b. At this time, part of the microwave energy within the microwave cavity 6 passes through the metal mesh plate 5a and forms a weak microwave electromagnetic field between the two metal mesh plates 5a and 5b, and a part of the microwave energy also passes through the metal mesh plate 5a. It is released from the plate 5b to the outside. The magnetron 1 is cooled by the air blown from the fan 9, and this air passes through the waveguide 3 and the power supply port 7 from the ventilation hole 3a to cool the lamp 8, and is then discharged through the metal mesh plates 5a and 5b. be done.

[Problem that the invention seeks to solve]

In the conventional microwave discharge light source device as described above, the light transmitting member 5 is made of a double metal mesh plate 5.
a, 5b has the advantage of minimizing the decrease in light emitted to the outside and minimizing the leakage of microwaves. 6 harmonics), the shielding effect is low, so there is a problem of generation of interference waves to other communication devices. To prevent this, there are methods, for example, to reduce the line pitch between the metal mesh plates 5a and 5b, or to further increase the number of layers of mesh plates, but in either case, the overall transmittance of light emitted to the outside decreases. I came across a problem.

The present invention was made to solve such problems, and an object of the present invention is to obtain a microwave discharge light source device that reduces leakage of harmonic microwaves without reducing the amount of lamp light emitted to the outside. shall be.

[Means for solving problems]

In the microwave discharge light source device according to the present invention, the waveguide is constructed of a member that reflects fundamental microwaves but transmits harmonic microwaves, and the outside of this member is coated with a microwave absorbing member. .

[Effect]

In this invention, among the microwaves oscillated by the magnetron, harmonic microwaves leak from the waveguide wall while propagating inside the waveguide and are absorbed by the microwave absorption member outside the waveguide. The harmonic microwave energy reaching the microwave cavity is reduced. As a result, the amount of harmonic microwaves leaking from the metal mesh plate to the outside can be reduced to below the reference value.

〔Example〕

FIG. 1 is a cross-sectional view showing an embodiment of the present invention, and numerals 1 to 10 are the same as the conventional one shown in FIG. 3, but the waveguide 3 in this invention reflects the fundamental microwave. However, it is constructed from a member made of a metal mesh plate that transmits harmonic microwaves. 1
Reference numeral 1 denotes a microwave absorbing member made of ferrite resin or the like having a thickness of 1 cm, which covers the outside of the waveguide 3, and the waveguide 3 is maintained by the strength of this microwave absorbing member 11. Note that the portion of the waveguide 3 that is not covered with the microwave absorbing member 11 is left as a ventilation hole 3a for blowing air from the fan 9.

In the microwave discharge light source device configured as described above, microwaves oscillated from the magnetron 1 are emitted into the waveguide 3. However, although the waveguide 3 has a sufficient shielding effect on fundamental microwaves, it has a low shielding effect on microwaves with short spatial wavelengths such as the 5th and 6th harmonics. The microwave leaks from the waveguide wall while propagating inside the waveguide 3, is absorbed by the microwave absorbing member 11 coated on the outside of the waveguide, and is converted into thermal energy. Thus, the fundamental microwave propagating through the waveguide 3 is emitted from the feed port 7 into the microwave cavity 6, causing the lamp 8 to discharge and emit light. In addition,
Most of the harmonic microwaves are absorbed by the microwave absorbing member 11, but some harmonics are absorbed by the cavity 6.
Even if it is introduced into the interior, the amount is extremely small, so even if it passes through the metal mesh plates 5a, 5b and is radiated to the outside, it will not affect other communication equipment, etc. It goes without saying that the longer the length of the waveguide 3, the higher the harmonic microwave absorption effect.

FIG. 2 shows another embodiment of this invention,
The outside of the microwave absorbing member 11 is further covered with a microwave reflecting member 12. According to this, harmonic microwaves that are not completely absorbed by the microwave absorbing member 11 and have passed through the microwave absorbing member 11 are reflected by the reflecting member 12 and can be reliably absorbed by the absorbing member 11. Thereby, even when the microwave absorbing member 11 is thin, a large absorption effect can be obtained.

〔Effect of the invention〕

As explained above, this invention consists of a waveguide made of a member that reflects fundamental microwaves but transmits harmonic microwaves, and by coating the outside of this waveguide with a microwave absorbing member, Leakage of harmonic microwaves to the outside can be significantly reduced without reducing the output of lamp light emitted within the microwave cavity. This has the effect of preventing radio wave interference to other communication devices.

[Brief explanation of drawings]

FIG. 1 is a sectional view of one embodiment of the present invention, FIG. 2 is a sectional view of another embodiment, and FIG. 3 is a sectional view of a conventional one. DESCRIPTION OF SYMBOLS 1... Magnetron, 3... Waveguide, 4... Microwave cavity wall, 5... Light transparent member, 5a, 5
b...Metal mesh plate, 6...Microwave cavity,
7... Power supply port, 8... Electrodeless discharge lamp, 11...
...Microwave absorbing member, 12...Microwave reflecting member. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A microwave oscillator, a waveguide for propagating microwaves emitted from the oscillator, and a microwave cavity in which a discharge lamp is disposed and at least a part of the wall is made of a metal mesh plate. In a microwave discharge light source device that includes a cavity and causes the lamp to discharge and emit light using a microwave electromagnetic field formed within the cavity, at least a portion of the waveguide reflects fundamental microwaves but does not reflect harmonic microwaves. 1. A microwave discharge light source device comprising a member that transmits waves, and at least a portion of the outside of the member is coated with a microwave absorbing member. 2. The microwave discharge light source device according to claim 1, wherein at least a portion of the outside of the microwave absorbing member is coated with a microwave reflecting member.