JP2005302646A - Flat discharge tube illumination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat discharge tube illumination device suppressing emission of jamming radio wave, without any apprehension of electric shock. <P>SOLUTION: The discharge tube 19 is formed by sealing a discharging gas between glass plates 11, 12, arranging phosphor layers 17, 18 on the inner surface of the glass plates 11, 12, and by forming an electrode 14 and a transparent electrode 15 on the outer surface thereof. The transparent electrode 15 is connected to a grounding end 28E of a driving circuit 28. The discharge tube 19 and the driving circuit 28 is housed in a globe 27 and, for example, mounted on a metal ceiling 31 of a wagon. A shield plate 34 is formed on an inner surface of a back case 35 constituting a part of the globe 27 in opposition to the electrode 15, and the grounding end 28E. The grounding end 28E is connected to the ceiling 31, and the discharge tube 19 is electromagnetically shielded by the shield plate 34 and the transparent electrode 15. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  In the present invention, a discharge gas is sealed in a flat sealed container having at least an illuminating surface dielectric plate, electrodes are formed opposite to each other with the dielectric plate and the discharge gas interposed therebetween, and a high-frequency power or a direct current pulse is formed between these electrodes. The present invention relates to a flat discharge tube illuminating device that emits light by applying and discharging.

  First, a conventional flat discharge tube disclosed in Patent Document 1, for example, will be described with reference to FIG. Dielectric flat plates 11 and 12 such as glass plates are arranged to face each other, and the peripheral portions of the opposing surfaces of the dielectric flat plates 11 and 12 are sealed with a sealing member (for example, sealing glass) 13 to form a flat sealed container 16. Is configured. A discharge gas is sealed in the sealed container 16, and electrodes 14 and 15 are attached to face each other with the dielectric plates 11 and 12 and the discharge gas interposed therebetween, thereby forming a discharge space. Phosphor layers 17 and 18 are formed on the opposing inner surfaces of the dielectric plates 11 and 12 so as to face each other. As the discharge gas, Xe (xenon) gas, mercury vapor, Ar (argon), Ne (neon) gas, or the like is used.

  As the light emission drive circuit of the flat discharge tube 19, for example, AC power from a commercial power source 21 is rectified and smoothed by a rectifying and smoothing circuit 22 to be a DC power source 23, and DC power from the DC power source 23 is high-frequency power by an inverter 24. This high frequency power is boosted by the transformer 25 and applied between the electrodes 14 and 15. By applying this high frequency power, a discharge is generated between the dielectric plates 11 and 12 (which is called a dielectric barrier discharge because it is a discharge through the dielectric plates 11 and 12), and is thereby formed by ionization of the discharge gas. Discharge plasma is generated, and the phosphor layers 17 and 18 are excited by the ultraviolet rays to irradiate natural light to the outside, that is, light emission occurs and the discharge tube 19 is turned on. The dielectric plate opposite to the illumination surface, for example, 11 may be a metal plate, which may also be used as the electrode 14. The electrode 15 on the illumination surface side is a transparent electrode.

For example, a flat discharge tube illuminator shown in FIG. 5 may be configured using such a flat discharge tube. The flat discharge tube 19 is housed in a transparent globe 27 made of, for example, a transparent resin material, and a drive circuit 28 including an inverter 24 and a transformer 25 is also housed in the globe 27 to form a flat discharge tube lighting device. A pair of power connectors 29H and 29E are attached to, for example, a side plate of the globe 27. The flat discharge tube lighting fixture is attached to, for example, the ceiling 31, and the DC power source 23 is connected to the power connectors 29H and 29E to be lit. For example, when this lighting device is used for lighting in a wagon car, the ceiling 31 is a top plate of the body of the wagon car, and the DC power source 23 is a storage battery mounted on the wagon car.
Japanese Patent Laying-Open No. 2003-31182 (FIG. 2)

  When the above-described flat discharge tube illuminator is actually used, the electrode 15 on the illumination surface is transparent with the front surface of the globe 27 removed for inspection or the like. is there. The voltage applied between the electrodes 14 and 15 is dangerous because the peak value is a high voltage of about 1 kV, for example, and some safety measures are required. Further, when the mounted position is relatively low, the driving power is a high-frequency or direct-current pulse of about 10 kHz to 100 kHz when the person 32 approaches the flat discharge tube illuminator with the person 32 standing. The high-frequency current leaks through the stray capacitance C1 generated during this period, and accordingly, the input current of the drive circuit 28 increases and the loss increases.

  According to the present invention, the illumination surface side transparent electrode of the flat discharge tube of the flat discharge tube lighting fixture is connected to the ground terminal of the discharge tube driving circuit.

  Since the transparent electrode is grounded, the transparent electrode and the human are in the same potential state, so there is no risk of electric shock even when touching the transparent electrode that is lit, and no high-frequency current leaks through the stray capacitance with the human .

An embodiment of the present invention is shown in FIG. In the drawings of the application, the same reference numerals represent the corresponding parts, and redundant description is omitted. In this example, the flat discharge tube 19 is housed in a transparent globe 27 and attached to, for example, the ceiling 31. In the present invention, the transparent electrode 15 on the illumination surface side is connected to the ground terminal 28 </ b> E of the drive circuit 28.
In this embodiment, a shielding plate 34 is provided in the vicinity of the surface opposite to the illumination surface of the flat discharge tube 19, that is, the back surface. In this example, the back side of the globe 27 is constituted by a back case 35 that covers the back side of the flat discharge tube 19 and the drive circuit 28, and the back case 35 is a molded product of, for example, a synthetic resin material. Further, a metal film as the shielding plate 34 is formed by, for example, electroless plating and electrolytic plating. The back case 35 itself may be made of a metal plate or a metal mesh to form the shielding plate 34. That is, in the example shown in FIG. 1, it can be said that the back case 35 is also used as the shielding plate 34. A shielding plate 34 separate from the globe 27 may be provided in the globe 27.

  In any case, the shielding plate 34 is connected to the ground connector 29E. In this example, the power connectors 29H and 29E are attached to the back case 35, and the power connector 29H to be connected to the anode of the DC power source 23 inside the back case 35 is connected to the positive terminal of the drive circuit 28. The power connector 29E to be connected to the cathode of 23 is connected to the negative terminal of the drive circuit 28, that is, the ground terminal 28E. Specifically, the drive circuit 28 is mounted on a wiring board, but the secondary side wiring of the transformer 25 (FIG. 4) connected to the transparent electrode 15 on the illumination surface side and the common potential wiring of the wiring board, that is, Wirings to be connected to the power connector 29E are connected to each other. This wiring board is connected to power connectors 29H and 29E. The flat discharge tube lighting fixture is attached to the ceiling 31 by tapping screws 41 screwed into the inner surface of the ceiling 31 from the inner surface of the back case 35, for example. Therefore, if the ceiling 31 is a metal plate of a vehicle, for example, the lug terminal 42 is sandwiched between the head of the tapping screw 41 and the shielding plate 34, and the lug terminal 42 is connected to the ground terminal 28E of the drive circuit 28. The shielding plate 34 can be grounded satisfactorily. In the case of a vehicle, the negative electrode of the power source 23 is usually connected to the vehicle body, that is, connected to the ceiling 31.

According to this configuration, even if a human hand accidentally touches the transparent electrode 15 on the illumination surface side, the transparent electrode 15 is at the ground potential, that is, the same potential as that human hand, so there is no risk of electric shock and it is safe. Further, even if a human head approaches the flat discharge tube lighting apparatus that is emitting light, for example, since both the human and the transparent electrode 15 are at the ground potential, a stray capacitance is not formed between them, and a high-frequency drive current leaks. There is no fear of doing so, and the power loss is reduced accordingly.
Further, in this example, since the rear side shielding plate 34 is provided, there is no possibility that the obstacle radio wave is radiated from the discharge tube. The thickness of the flat discharge tube 19 is, for example, about 2.5 mm, which is sufficiently small compared with the wavelength of the driving high frequency, and the area of the transparent electrode 15 is as wide as, for example, about 10 × 15 cm ² , so that the flat discharge tube 19 is grounded. Even in the state of being sandwiched between the transparent electrode 15 and the grounded shielding plate 34, it is possible to suppress the emission of disturbing radio waves. In particular, as shown in the figure, when the shielding plate 34 is surrounded to some extent by the side peripheral surface of the flat discharge tube 19, sufficient shielding is performed.

Further, as in this example, when the back cover 35 and the shielding plate 34 are used together, it is not necessary to provide the shielding plate 34 as a separate component, so that the number of components can be reduced and the configuration can be reduced.
Since the transparent electrode 15 is used for current shielding, it can be constructed at a lower cost than when the entire flat discharge tube 19 is shielded.
Another embodiment of the present invention is shown in FIG. In this embodiment, the heat radiating plate 37 of the drive circuit 28 is extended in close proximity to and substantially opposite the entire back surface of the flat discharge tube 19, and the heat radiating plate 37 is connected to the ground terminal 28 </ b> E of the drive circuit 28. For example, the heat sink 37 is connected to the power connector 29E. The transparent electrode 15 is connected to the ground terminal 28E as in the above embodiment.

Also in this embodiment, safety is maintained as in the embodiment shown in FIG. 1, power loss is small, emission of disturbing radio waves can also be suppressed, and it is cheaper than the case where the entire flat discharge tube 19 is shielded. It will be readily understood that it can be configured.
An embodiment in which the present invention is applied when a flat discharge tube lighting fixture is attached to a grounded conductor plate such as a ceiling in a wagon car will be described with reference to FIG. In this embodiment, the ceiling 31 is, for example, a metal plate of a vehicle body ceiling of a wagon car, and a flat discharge tube illuminator housed in the globe 27 on the ceiling 31 is opposed to the surface opposite to the illumination surface, that is, the electrode 14. Can be attached. The transparent electrode 15 is connected to the ground terminal 28E of the drive circuit 28.

  A shielding plate 34 is not disposed between the electrode 14 and the ceiling 31. However, the ceiling 31 is at the ground potential, and the flat discharge tube 19 is electromagnetically shielded by this and the electrode 14 connected to the ground end 28E. The same effects as those of the illustrated embodiment can be obtained. 2 and 3, the connection between the ground end 28E of the drive circuit 28 and the ceiling 31 is shown in a simplified manner. For example, as shown in FIG. 1, the back case 35 or the globe 27 is attached to the ceiling 31 with tapping screws. The ground terminal 28E is connected to this. In any case of FIGS. 1 to 3, the illumination surface side of the globe 27 can be removed or opened for repair and inspection.

  A heat insulating material layer and a member layer are attached to the inner surface of the metal plate ceiling 31 of the wagon car, and the thickness of this layer varies depending on the vehicle type. Accordingly, the shielding effect on the flat discharge tube 19 varies depending on the mounting state of the flat discharge tube lighting fixture. However, if the flat discharge tube lighting apparatus of the embodiment shown in FIG. 1 or FIG. 2 is used, a predetermined shielding effect is always obtained.

Sectional drawing which shows embodiment of this invention. Sectional drawing which shows other embodiment of this invention. Sectional drawing which shows other embodiment of this invention. Sectional drawing which shows the conventional flat discharge tube. Sectional drawing which shows the possible example of the lighting fixture using a planar discharge tube.

Claims (4)

Discharge gas is sealed in a flat sealed container whose illumination surface side is a dielectric flat plate, and a pair of electrodes facing each other with the dielectric flat plate and the discharge gas interposed therebetween is formed. The electrode on the illumination surface side is transparent. In a flat discharge tube lighting fixture that is an electrode,
The flat discharge tube lighting apparatus, wherein the illumination surface side electrode is connected to a ground terminal of a driving circuit for driving the flat discharge tube.   2. The flat discharge tube lighting device according to claim 1, wherein a shield plate is provided on a surface opposite to the illumination surface of the flat discharge tube, and the shield plate is connected to the ground end.   The flat discharge tube illuminating device according to claim 2, wherein a case surrounding the surface opposite to the illumination surface of the flat discharge tube is provided, and the case also serves as the shielding plate.   The drive circuit is juxtaposed with the flat discharge tube, the conductive heat sink of the drive circuit is extended opposite to the surface opposite to the illumination surface of the flat discharge tube, and the conductive heat sink is connected to the ground end. The flat discharge tube lighting fixture according to claim 1, wherein:

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