JP2009181762A - Microwave discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a microwave discharge lamp in which impedance matching between a microwave oscillation source and the discharge lamp can be made even without an expensive matching device. <P>SOLUTION: In the microwave discharge lamp, a lead wire of a discharge lamp having a pair of electrodes is connected to a microwave oscillator source in a discharge container arranged in a metallic chamber, and microwave is supplied to light the lamp. The microwave discharge lamp includes an impedance adjusting mechanism in which surroundings of the lead wire of the discharge lamp in the metallic chamber are enveloped by a metal wall. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a discharge lamp that is lit using microwaves.

In recent years, the demand for high-pressure discharge lamps is increasing not only for general lighting but also for headlights for automobiles and backlights for projectors in place of halogen lamps because of their high efficiency and high color rendering.
In particular, in a high-pressure discharge lamp using a microwave, since it is possible to couple electromagnetic energy to a luminescent substance in the light emitting space without having an electrode in the light emitting space, it is possible to realize an electrodeless discharge lamp.
Since electrodeless discharge lamps do not have electrodes in the light emitting part, there is no reduction in luminous efficiency due to electrode consumption, and high luminous efficiency such as sulfur, but it reacts with electrode materials, so it can be used in electroded lamps. Since it is possible to use a luminescent material that cannot be used, it is expected from the viewpoint of extending the life and efficiency of the lamp.

However, such an electrodeless lamp cannot be used in applications where a point light source is indispensable, such as a projector backlight, because of its low optical efficiency because the light emitting portion extends over the entire discharge space. .
In order to solve this problem, a technique has been disclosed in which a discharge concentrator is installed in a discharge space while using microwaves, and is discharged at the tip of the discharge concentrator so as to make a point light source.
JP 2007-80705 A

Here, when performing microwave lighting, it is necessary to couple the microwave appropriately to the discharge space, that is, to match impedance.
At this time, when impedance matching between the microwave oscillation source and the discharge lamp is not achieved, the microwave transmitted from the microwave oscillation source to the discharge lamp is not coupled to the discharge lamp and the microwave power is reflected. When the reflected power is large, problems such as failure of the microwave oscillation source and overheating of the transmission line occur.
By using a matching device such as a stub tuner, it is possible to achieve impedance matching, but this leads to an increase in the size and cost of the device.

  An object of the present invention is to easily achieve impedance matching in a discharge lamp using microwaves.

In order to solve this problem, a microwave discharge lamp device of the present invention includes a metal chamber, a discharge lamp disposed inside the metal chamber, and a discharge lamp disposed inside the metal chamber. A discharge lamp device having a reflecting mirror for reflecting the light, wherein the discharge lamp has a pair of electrodes in a discharge vessel, and at least one electrode is connected to a lead wire through a metal foil, and the lead A microwave discharge having a wire connected to a microwave oscillation source and having an impedance adjustment mechanism in which at least part of the lead wire of the discharge lamp and the sealing portion is surrounded by a metal wall in the metal chamber It is a lamp device.
Further, the means for transmitting the microwave energy from the microwave oscillation source to the discharge lamp may be configured to use a transmission line or a microstrip line comprising an inner conductor and an outer conductor surrounding the inner conductor.

  According to the present invention, it is possible to easily perform impedance matching only by changing the dimension of the metal wall as an impedance adjustment mechanism in accordance with the impedance of the discharge lamp, and microwave oscillation by reflection of microwave power Problems such as source failure and overheating of the transmission line can be solved.

  The best mode of the present invention will be described below with reference to examples.

FIG. 1 is a sectional view showing an outline of a microwave discharge lamp of the present invention.
In FIG. 1, a discharge lamp 1 has a pair of electrodes 3a and 3b in a discharge vessel 2 in which a starting rare gas and a luminescent material are sealed, and each electrode has molybdenum metal foils 4a and 4b and lead wires. 5a and 5b are connected.
The microwave from the microwave oscillation source has an electric power of 50 W and a frequency of 2.45 GHz, is transmitted through the coaxial cable 6, and is microwave energy from the lead wire 5 a electrically connected to the inner conductor of the coaxial cable to the discharge lamp 1. Are combined and the discharge lamp is lit.
The discharge lamp 1 is housed in a metal chamber 7 in order to prevent the microwave from leaking outside.

The elliptical reflecting mirror 8 arranged in the metal chamber 7 is arranged so that the tips of the pair of electrodes 5a and 5b of the discharge lamp substantially coincide with the focal position, and the reflected light from the elliptical reflecting mirror 8 is a metal. The light is taken out from the light outlet hole 9 of the chamber 7.
The light guide hole 9 has a diameter of 10 mm and can take out the light emitted from the discharge lamp 1 and reflected by the elliptical reflecting mirror 8, but the microwave does not leak to the outside.
The metal chamber 7 is connected to the outer conductor of the coaxial cable 6, and an impedance adjusting mechanism 10 is provided inside. This impedance adjustment mechanism has a lead wire to a cylindrical lamp with a diameter of 7 mm and a length of 16 mm and a hole partially covered with a metal wall to surround a part of the lamp sealing part. However, by changing the size of this hole, it becomes possible to change the impedance on the discharge lamp side as seen from the microwave oscillation source, matching the impedance of the microwave oscillation source and the discharge lamp to reduce the reflected power. Can be reduced.

  Table 1 shows the dimensions of the impedance adjusting mechanism and the reflected power when this discharge lamp is lit at 50 W.

表１に示したように、インピーダンス調整機構の孔の直径を変えることにより、金属壁の大きさを変化させ、ランプへのリード線及びランプ封止部の一部との距離を変化させることで、マイクロ波発振源からみた放電ランプのインピーダンスを変えることができ、最適な寸法を選ぶことにより反射電力を低減することが可能である。
尚、放電ランプの仕様（電力・封入物など）が異なる場合には、その放電ランプを点灯した時に反射電力が少なくなるように、インピーダンス調整機構の孔の寸法を適宜選択し、金属壁の大きさを変化させればよい。
また、インピーダンス調整機構の孔の形状は円筒状のものに限られることはなく、矩形形状（角柱状）などでもインピーダンス調整の働きをもつ。

As shown in Table 1, by changing the diameter of the hole of the impedance adjustment mechanism, the size of the metal wall is changed, and the distance between the lead wire to the lamp and a part of the lamp sealing portion is changed. The impedance of the discharge lamp as viewed from the microwave oscillation source can be changed, and the reflected power can be reduced by selecting an optimum dimension.
If the specifications of the discharge lamp (power, enclosure, etc.) are different, select the dimensions of the impedance adjustment mechanism hole so that the reflected power is reduced when the discharge lamp is lit, and the size of the metal wall Change the length.
Moreover, the shape of the hole of the impedance adjustment mechanism is not limited to a cylindrical shape, and a rectangular shape (rectangular column shape) or the like also has a function of impedance adjustment.

Further, the transmission line for transmitting the microwave from the microwave oscillation source to the discharge lamp 11 as shown in FIG. In this case, the lead wire 15a may be connected to the microstrip line 16.

Used as a light source for automobiles and projectors.

Sectional drawing which shows the microwave discharge lamp apparatus which concerns on this invention. Sectional drawing which shows the other form of the microwave discharge lamp apparatus which concerns on this invention.

Explanation of symbols

1, 11 Discharge lamp 2, 12 Discharge vessel 3a, 3b, 13a, 13b Electrode 4a, 4b, 14a, 14b Metal foil 5a, 5b, 15a, 15b Lead wire 6 Coaxial cable 7, 17 Metal chamber 8, 18 Reflector 9, 19 Light outlet hole 10, 20 Impedance adjustment mechanism 16 Microstrip line

Claims (3)

A microwave discharge lamp device having a metal chamber, a discharge lamp disposed inside the metal chamber, and a reflecting mirror disposed inside the metal chamber and reflecting light from the discharge lamp;
The discharge lamp has a pair of electrodes in a discharge vessel, at least one electrode is connected to a lead wire through a metal foil, and the lead wire is connected to a microwave oscillation source,
A microwave discharge lamp device including an impedance adjusting mechanism in which at least a part of a lead wire and a sealing portion of the discharge lamp is surrounded by a metal wall in the metal chamber.
The discharge lamp according to claim 1, wherein the microwave energy from the microwave oscillation source is transmitted to the discharge lamp using a microwave transmission line including an inner conductor and an outer conductor surrounding the inner conductor. A microwave discharge lamp device in which the lead wire is electrically connected to the inner conductor.
2. The discharge lamp according to claim 1, wherein the microwave energy from the microwave oscillation source is transmitted to the discharge lamp using a microstrip line, wherein at least one lead wire of the discharge lamp is connected to the microstrip line. Wave discharge lamp device.

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