JPS6233718B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a microwave discharge light source device that utilizes light emission by microwave discharge.

Figures 1 and 2 show a conventional microwave discharge light source device, with Figure 1 being a schematic diagram and Figure 2 being a schematic configuration diagram.
The figure is a power supply circuit diagram. In the figure, 1 is a microwave oscillator consisting of a magnetron that generates microwaves, 2 is a magnetron antenna, 3 is a waveguide that transmits the microwave from the microwave oscillator 1, and 4 is a spherical surface. It is a cavity wall made of aluminum or the like, consisting of a section 5 and a cylindrical section 6 following it, and the inner surface has light reflective properties. Reference numeral 7 denotes a metal mesh plate attached to a flange portion 10 extending from the end of the cylindrical portion 6 of the cavity 4 with a presser flange 8 and a presser screw 9, and constitutes a microwave cavity 11 with the cavity wall 4. . Reference numeral 12 denotes a microwave power supply port provided at the joint between the waveguide 3 and the cavity wall 4. Reference numeral 13 denotes a spherical electrodeless discharge lamp disposed near the center of the spherical part 5, and the outer wall is made of quartz glass or the like. It is formed by a rare gas such as argon, mercury,
Metals such as iron and halogens such as iodine are enclosed. 14 is a protrusion provided on a part of the outer wall of the discharge lamp 13, and one end of a discharge lamp support 15 made of a low-loss dielectric material such as quartz glass is fitted into a flared discharge lamp support 16. , discharge lamp 13 into cavity 1
It is supported within 1. Reference numeral 17 is a discharge lamp support support part provided in a part of the cavity wall 4 into which the other end of the discharge lamp support 15 is inserted and supports the discharge lamp support 15; A lens 19 is used to focus the emitted light onto a surface to be irradiated (not shown), and 19 is a microwave leakage detector installed outside the microwave cavity 11. Detection level of wave leakage amount
It is set to 1mW/ ^cm2 . In Figure 2, PS
is the input power supply, R is the power intermittent relay, Ra and Rb are the normally open contacts of the power intermittent relay R, SN is the power on switch, SF is the power off switch, 19a is the normally closed contact operated by the microwave leakage detector 19, T is the power transformer, Ti is the primary winding of the power transformer T, TH is the high voltage winding of the power transformer T,
TF is the filament winding of the power transformer T, D ₁₁ ,
D ₁₂ is a rectifier diode, C ₁₁ and C ₁₂ are capacitors, and rectifier diodes D ₁₁ and D ₁₂ and capacitors
Full-wave voltage doubler rectification is performed with C ₁₁ and C ₁₂ , and the magnetron 1 is operated with this rectified power supply.

In the microwave discharge light source device configured in this way, first, when the power supply switch SN is turned on, power supply PS - power supply switch SN - power supply changeover switch SF - normally closed contact 19a of microwave leakage detector 19 - power supply intermittent. A closed circuit of relay R is formed and power supply intermittent relay R is energized, thereby closing its normally open contacts Ra and Rb.
By closing this normally open contact Rb, the power supply intermittent relay R is self-maintained, and by closing the normally closed contact Ra, the power from the power supply PS is transferred to the microwave leakage detector 1.
9 and the primary winding Ti of the power transformer T. A voltage is induced in the high-voltage winding TH and filament winding TF of the power transformer T, and the voltage of the induced high-voltage winding TH is full-wave voltage doubler rectified and applied to the magnetron 1. The voltage is applied to the filament of the magnetron 1, and the magnetron 1 operates.
The microwaves generated by the operation of the magnetron 1 propagate through the waveguide 3 and are radiated into the microwave cavity 11 through the feed port 12, forming a microwave electromagnetic field within the microwave cavity 11. do. 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 cause, and light with a specific emission spectrum depending on the type of encapsulated metal is emitted. At this time, discharge occurs near the tube wall of the discharge lamp 13. That is, the light emission is spherical, and since the discharge lamp 13 is located near the center of the spherical part 5, the reflected light passes through the vicinity of the discharge lamp 13 again due to light reflection from the spherical part 5 forming the cavity 4. It turns out. This reflected light and the direct light from the discharge lamp 13 are radiated outward through the metal mesh plate 7, and the radiated light is focused onto a necessary irradiated surface by a condenser lens 18 or the like. . Then, after turning off the power cutoff switch SF, the power intermittent relay R
becomes de-energized, its normally open contacts Ra and Rb are opened, and the magnetron 1 is stopped.

On the other hand, in this microwave discharge light source device, the mesh pitch and aperture ratio of the mesh in the metal mesh plate 7 are controlled so that the amount of microwave leakage from the metal mesh plate 7 is suppressed to 1 mW/cm ² or less from its startup to during operation. Because of the design, the microwave leakage detector 19 normally does not operate. However, for some reason, the metal mesh plate 7
When the ^amount of microwave leakage from the and Rb
is opened, and the magnetron 1 is stopped. As a result, there is no leakage of microwaves from the metal mesh plate 7, and there is no adverse effect on the human body.

By the way, in this type of microwave discharge light source device, the discharge of the electrodeless discharge lamp 13 shifts from discharge of rare gas to discharge of metal gas, that is, as the gas pressure inside the electrodeless discharge lamp 13 increases, , the absorption efficiency of the microwave energy of the discharge increases, and the microwave energy becomes more concentrated in the discharge lamp. On the other hand, the leakage of microwaves from the metal mesh plate 7
1. Since it is proportional to the microwave energy near the inner side, it decreases as the absorption efficiency of the microwave energy of the discharge increases. In other words, the amount of microwave leakage from the metal mesh plate 7 reaches its maximum immediately after _t0 when the discharge lamp 13 is started, as shown by curve A in FIG. 3, and then gradually decreases as the discharge of metal gas shifts. It is. Further, the amount of microwave leakage from the metal mesh plate 7 is influenced by the mesh pitch and the aperture ratio of the mesh in the metal mesh plate 7, and as the mesh pitch increases,
Furthermore, as the aperture ratio increases, the amount of microwave leakage increases. Therefore, the maximum amount of microwave leakage from the metal mesh plate 7 immediately after starting the discharge lamp 13 should not exceed the detection level Pr of the microwave leakage detector 19 (1 mW/cm ² in this example). The mesh pitch and aperture ratio of the mesh in the metal mesh plate 7 were determined.

However, in the microwave discharge light source device configured in this way, the microwave leakage detector 19
The detection level Pr is always constant from startup to operation, and the mesh pitch and aperture ratio of the metal mesh plate 7 are set small so that the amount of microwave leakage immediately after startup does not exceed the above detection level. The amount of light from the metal mesh plate 7, which is proportional to , is limited, and the light from the discharge lamp 13 cannot be used effectively.

This invention has been made in view of the above points, and includes an electrodeless discharge lamp disposed within a microwave cavity at least partially composed of a metal mesh plate,
A microwave discharge light source device that lights this electrodeless discharge lamp using microwaves is equipped with a microwave leakage detector that detects microwaves leaking from the metal mesh plate, and also a microwave leakage detector that detects microwaves leaking from the metal mesh plate. A detection level setting device is installed to set the detection level of the wave leakage detector higher than the detection level of the microwave leakage detector when the electrodeless discharge lamp is stably lit, to prevent harmful effects on the human body due to microwave leakage from the metal mesh plate. , and to increase the amount of light that can be extracted from the metal mesh plate.

An embodiment of this invention is shown below in Figures 4 and 5.
To explain based on the figure, reference numeral 19 in the figure is a microwave leak detector that is installed outside the microwave cavity 11 and detects microwave leakage from the metal mesh plate 7, and converts the detected amount of microwave leakage into a voltage. This voltage is compared with a preset reference voltage (detection level), and when it exceeds this reference voltage, it operates and opens the normally closed contact 19a. 191 is a detection level setting device for setting the detection level of the microwave leakage detector 19, and the microwave leakage amount is set from _t0 at the time of starting the electrodeless discharge lamp 13 to t1 after a predetermined period of time (from ₁ to 2 seconds to several seconds).
Set the detection level corresponding to Pr ₀ (>Pr), and set the detection level corresponding to t ₁
Thereafter, the setting is changed to a detection level corresponding to the microwave leakage amount Pr (for example, 1 mW/cm ² that does not have a negative effect on the body).

The mesh pitch and aperture ratio of the metal mesh plate 7 are set so that the leakage microwave from the metal mesh plate 7 is less than Pr when the electrodeless discharge lamp 13 is stably lit, and when the detection level setting device 191 is started, t ₀ The detection level _from
The value was set to be slightly larger than the maximum microwave leakage amount at the time of starting No. 3, and the relationship is shown by curves A ₁ and B ₁ in FIG. In FIG. 5, the curve A ₁ is the amount of microwave leakage from the metal mesh plate 7, and the curve B ₁ is the amount of microwave leakage corresponding to the detection level of the detection level setting device 191.

The microwave discharge light source device configured in this manner operates in the same manner as that described in the conventional example above, but the microwave leakage detector 19
Since the detection level from immediately after the electrodeless discharge lamp 13 is started to a predetermined time period is larger than that when the electrodeless discharge lamp 13 is stably lit, the mesh pitch and aperture ratio of the metal mesh plate 7 are increased. This allows a large amount of light to be emitted from the metal mesh plate 7, and when the electrodeless discharge lamp 13 is stably lit, the amount of microwave leakage is always suppressed to less than Pr (for example, 1 mW/cm ² ), which has an adverse effect on the human body. Pr (for example, 1 mW/cm ² ) from t ₀ immediately after starting the electrodeless discharge lamp 13 until after a predetermined time t ₁ has elapsed.
As mentioned above, since the time is very short, it does not have any adverse effects on the human body.

Note that if a microcomputer, such as Intel 8085, is used as the detection level setting device 13, Pr ₀ and
It is possible to easily change Pr and change the time _t1 , and the design latitude is improved.

As described above, the present invention is a device in which an electrodeless discharge lamp is disposed in a microwave cavity, at least a part of which is made up of a metal mesh plate, and the electrodeless discharge lamp is lit by microwaves. In addition to installing a microwave leak detector that detects microwave leakage from the plate, the detection level of the microwave leak detector from immediately after the electrodeless discharge lamp starts until a predetermined time is measured to stabilize the electrodeless discharge lamp after the elapse of the predetermined time. We have installed a detection level setting device that sets the detection level higher than the detection level of the microwave leakage detector when the lamp is turned on, so that there is no harmful effect on the human body due to microorganisms leaking from the metal mesh plate, and the light from the electrodeless discharge lamp can be transmitted through the metal mesh plate. It has the effect of being able to be effectively taken out to the outside.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the configuration of a microwave discharge light source device, Fig. 2 is a diagram showing a power supply circuit of a conventional microwave discharge light source device, and Fig. 3 is a diagram showing microwave leakage when operating with the power supply shown in Fig. 2. Figure 4 is a diagram showing the power supply circuit of a microwave discharge light source device according to an embodiment of this invention, and Figure 5 is a diagram showing the amount of microwave leakage when operated with the power supply shown in Figure 4. be. In the figure, 1 is a magnetron, 7 is a metal mesh plate, 11 is a microwave cavity, 13 is a discharge lamp,
19 is a microwave leak detector, and 191 is a detection level setter. In each figure, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] 1. A microwave oscillator 1 that generates microwaves;
A microwave cavity 11, at least a part of which is composed of a metal mesh plate 11, confines microwaves generated by the microwave oscillator 1; an electrodeless discharge lamp 13 disposed within the microwave cavity 11; A microwave leakage detector 1 detects leakage microwaves from a metal mesh plate 11 and cuts off the supply of microwaves into the microwave cavity 11 when the amount of microwave leakage exceeds a detection level.
In the microwave discharge light source device equipped with 9, the detection level of the microwave leakage detector 19 is determined by the magnitude of the detection level of the microwave leakage detector 19 from immediately after the start of the electrodeless discharge lamp 13 until a predetermined time period when the electrodeless discharge lamp becomes stable after the elapse of this predetermined time period. A microwave discharge light source device comprising a detection level setter 191 that sets the detection level to be larger than the level when the light is turned on. 2. The microwave discharge light source device according to claim 1, wherein the detection level setter 191 is configured by a microcomputer.