JPS638050Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a microwave discharge light source device that lights an electrodeless lamp using microwaves generated by a microwave oscillator.

Compared to general light source devices that have conventional electrode lamps, this type of light source device has a faster rise in luminous flux, a shorter restart time, and is less likely to deteriorate due to electrode wear because it is an electrodeless lamp. It has recently attracted attention because it has advantages such as long lamp life.

FIG. 1 is a longitudinal cross-sectional view showing the configuration of this type of microwave discharge light source device, in which 1 is a microwave oscillator, here a magnetron, 2 is its antenna,
3 is a waveguide, 4 is a microwave cavity whose inner shape is at least rotationally symmetrical, here it is formed into a cup shape, and 5 is a microwave power supply provided at the junction of this cavity 4 and the waveguide 3. 6 is a nearly spherical electrodeless lamp fixed in the cavity 4 by a support 7; 8 is a fan for cooling the magnetron 1 and the lamp 6; 9 is provided in a part of the waveguide 3; A ventilation hole, 10, a mesh plate covering the front surface of the cavity 4, 11
is a box that covers the magnetron 1, waveguide 3, cavity 4, etc. Next, the operation of the above-mentioned device will be explained.

First, microwaves generated by the magnetron 1 are radiated from the antenna 2 into the waveguide 3.
The radiated microwave propagates within the waveguide 3 and is radiated into the cavity 4 through the feed port 5, forming a microwave electromagnetic field within the cavity 4 and lighting the lamp 6. .

By the way, since the electrodeless lamp 6 is usually made of quartz glass, devitrification of the quartz glass generally occurs at the end of its life, fatigue of the material due to heat is added, and the microwave radiation eventually explodes. This causes contamination of the inner surface of the cavity 4 and damage to the support body 7 and mesh plate 10, and furthermore, it can be said that this is a situation that must be avoided from the standpoint of worker stability. However, there is no example of a safety measure for this type of light source device at the end of the lamp's life, and a solution has been desired.

This idea was made in consideration of the above points, and the light output of electrodeless lamps decreases at the end of their life due to a decrease in light transmittance due to devitrification, a shift in microwave matching due to shape changes, etc. With this in mind, if the set light output is not obtained from the electrodeless lamp even after a predetermined period of time has passed after driving the microwave oscillator, the power to the device will be shut off to prevent damage to the lamp. It is an object of the present invention to provide a microwave discharge light source device.

An embodiment of this invention will be described below with reference to FIG. FIG. 2 is a circuit diagram showing an embodiment of the microwave discharge light source device according to this invention. Secondary winding 1S, 2
This is a high voltage transformer equipped with S. A series circuit of a first capacitor C ₁₁ and a first diode D ₁₁ is connected to both ends of the secondary winding 1S of this transformer T, and a second capacitor C ₁₂ and a second diode D whose connection point is grounded are connected to each other. The series circuit with ₁₂ is connected in antiparallel, and these form a full-wave voltage doubler rectifier circuit. Further, the secondary winding 2S of the transformer T is connected to a microwave oscillator, here a cathode (filament) of a magnetron 1 whose anode is grounded. In this case, one end of the secondary winding 2S is also connected to the connection point between the first capacitor _C11 and the first diode _D11 .

The microwave generator 12 is configured as described above, and thereby the magnetron 1 generates microwaves to light the electrodeless lamp 6 shown in FIG. 1.

Reference numeral 16 denotes a power switch for supplying a signal instructing power on/off to the microwave generator to a control section 18, which will be described later. Reference numeral 13 denotes the electrodeless lamp 6.
A detection unit that is mainly composed of a photoelectric conversion element such as a photodiode that converts light from the outside into an electrical signal. 1
Reference numeral 7 is composed of a comparator circuit and a timer circuit using an operational amplifier. After a predetermined period of time has elapsed after driving the microwave oscillator, a comparison section compares the signal from the detection section 13 with a preset value at the lowest light intensity allowed for normal lighting. The detection value is set equal to the minimum value of the detection value output from the detection unit 13 during the time period in which the detection section 13 is performed. 18 opens and closes the opening/closing contact 14 in accordance with the opening and closing of the power switch 16, and also opens and closes the opening/closing contact 14 when a signal indicating that the output light amount of the electrodeless lamp 6 is less than a set value is output from the comparing section 17.
This is a control unit that functions to open the door. 15 is a detection section 13, a power switch 16, a comparison section 17, and a control section 1.
This is a control device consisting of 8 parts.

Therefore, in the embodiment of this invention, a switching contact 14 is provided on the primary side of the transformer that drives the magnetron 1, and the switching contact 14 is closed by operating the power switch 16, and after a predetermined period of time has elapsed after the magnetron 1 is driven. When the preset light output cannot be obtained from the electrodeless lamp 6 even when the electrodeless lamp 6
4 is provided with a control device 15 that opens the door.

Further, according to the present invention, in the microwave discharge light source device, the power supply is immediately cut off by detecting a decrease in the light output at the end of the lamp life, so that damage to the lamp can be prevented.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing the structure of a microwave discharge light source device, and FIG. 2 is a circuit diagram showing an embodiment of the microwave discharge light source device according to this invention. 1 is a magnetron, 6 is an electrodeless lamp, 13 is a detection unit, 14 is a switching contact, 15 is a control device, 16
is a blinking switch, 17 is a comparison section, 18 is a control section,
Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of utility model registration request] An electrodeless lamp is lit by microwaves generated by a microwave oscillator,
A switching contact provided on the primary side of the transformer that drives the microwave oscillator, and a control for opening the switching contact if a predetermined light intensity is not obtained within a predetermined time after driving the microwave oscillator. The control device includes a power switch that turns on and off the power, a detection section that detects the light intensity from the electrodeless lamp, and a detection value of the detection section that is set in advance. and a control section that forms a control signal for the opening/closing contact based on the output signal of the comparison section and the power-on signal of the power switch, which compares the set value after a predetermined period of time has elapsed after driving the microwave oscillator. A microwave discharge light source device characterized by: