JPS631682B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a lighting fixture that prevents high frequency noise generated by a discharge lamp from being transmitted to the power source side.

In general, discharge lamps such as fluorescent lamps are widely used as light sources for lighting equipment, but these discharge lamps contain high frequency components when turned on and off every half cycle of the power supply. This was transmitted to the power supply side and became high frequency noise (radio noise). In particular, recently, as shown in Figure 1, an electronic high-performance, high-efficiency lighting circuit using a high-frequency inverter that oscillates at several tens of KHz has been proposed. When used, the problem of high frequency noise was noticeable.

The lighting circuit shown in FIG. 1 will be explained. In the figure, 11
is an input terminal of a commercial power supply, and supplies commercial AC power to the lighting circuit 12 that generates high-frequency power. The lighting circuit 12 is constructed by sequentially connecting a high frequency noise prevention circuit 14, a rectifier 15, and an inverter 16 that oscillates at several tens of KHz from the input end, and supplies high frequency power to the discharge lamp 17. Here, the high frequency noise prevention circuit 14 is constituted by, for example, a balun transformer 18 and a capacitor 19 provided between its output terminals. Further, the rectifier 15 temporarily converts the commercial AC power supplied via the high frequency noise prevention circuit 14 into DC power. Further, although not shown, the inverter 16 is a well-known inverter composed of, for example, a pair of push-pull connected transistors or an inverter transformer, and obtains high-frequency power from the DC power.

In this way, when the discharge lamp 17 is lit at high frequency, high frequency noise is generated from the discharge lamp 17 and the inverter 16 themselves. This noise usually returns to the input terminal 11 either directly through a circuit line or indirectly through stray capacitance, and tends to cause a high frequency noise disturbance of 500 KHz to 1500 KHz. Therefore, as shown in FIG.
is provided to prevent direct noise feedback via the circuit line.

However, when such a lighting circuit is applied to an actual lighting fixture, it is not sufficient to prevent noise due to the relationship with the constituent members of the lighting fixture.
For example, as shown in FIG. 2, when applied to a multi-lamp type lighting equipment such as a chandelier, the lighting circuit 12 and the high frequency noise prevention circuit 14 are configured on a printed circuit board _12P and installed inside the equipment case 20. It will be done. Further, the discharge lamp 17 is provided in a lamp 22 supported at the tip of an arm 21 extending radially from the appliance case 20. And lighting circuit 12
and the discharge lamp 17 are connected by an output line 23 passing through the pipe-shaped arm 21. Also, lighting circuit 1
The input side of the device 2 is connected to the input end 11 through an input line 26 passing through a pipe structure support 25 connected to the upper center of the instrument case 20. This input end 11 is normally connected to indoor wiring provided on the ceiling surface of the room.

A lighting fixture with such a configuration generally has a fixture case 20, an arm 21, and a lighting fixture 2 from the viewpoint of mechanical strength.
2 and the support column 25 are each made of a metal material. That is, it is made of electrically conductive material. Therefore, in terms of electrical noise, a conductor 28 as shown in FIG. 1 exists. This conductor 28
are the instrument case 20 and the arm 2 made of the conductive material.
1. It is a part of the lamp 22 and is equivalent to the support 25. In this case, stray capacitance exists between the conductor 28 and the circuit. Regarding high frequency noise, it is obvious that the amount of stray capacitance is reflected in the amount of noise fed back to the power source.

Here, if we consider the conductor 11 by dividing it into the constituent parts _shown in FIG.
There is a stray capacitance C ₂₁ between the device case 20 and the lighting circuit 12, a stray capacitance C ₂₀ between the appliance case 20 and the lighting circuit 12,
Stray capacitance C ₂₅ between the pillar 25 and the input line 26
will exist. Among these, the parts with particularly large stray capacitance due to the structure are the pillar 25 and the input line 2.
6 and between the arm 21 and the output line 23. Although it is difficult to express the stray capacitance C using a quantitative formula, the tendency can be expressed using a capacitance formula (C=εs/d). Here, d is the distance between the poles, s is the pole area, ε
is the dielectric constant of air.

As is clear from the above equation, the stray capacitance C
increases if the distance d between poles is small. In this case, the pole area s is determined by the length of the connecting wire, the conductive part of the circuit,
This corresponds to the area of the conductive part of the device, and the larger this part, the greater the stray capacitance. Therefore, as described above, between the support 25 and the input line 26 and between the arm 21 and the output line 23, the distance d between poles is small and the distance d is relatively long. That is, it can be seen that since the pole area s is large, the stray capacitances C ₂₅ and C ₂₁ become large. Therefore, in order to reduce these stray capacitances, it is possible to increase the diameter of the arm 21 and the support column 25, or to shorten their length, but there is a limit to this degree from a decorative standpoint. Yes, but it's actually not very effective.

Therefore, the high frequency noise generated in the discharge lamp 17 is transmitted from the output line 23 to the arm ₂₁ via the stray capacitance C21, in addition to direct feedback via the circuit.
It passes through the instrument case 20, which is a conductor, and the pillar 25,
It reaches the input line 26 again via the stray capacitance C ₂₅ ,
A large amount of noise was fed back to the power supply from this input line 26.

An object of the present invention is to provide a lighting fixture in which the amount of noise feedback is reduced by interposing an insulator in a part of the fixture member constituting a noise feedback circuit via stray capacitance.

The present invention will be described below with reference to an embodiment shown in FIGS. 3 and 4. Note that the same reference numerals are given to the parts corresponding to those of the conventional device shown in FIGS. 1 and 2, and the explanation thereof will be omitted. As shown in FIG. 4, the circuit configuration of the lighting fixture of the present invention is no different from that shown in FIG. 1. A feature of the present invention is that when actually constructing a lighting fixture, for example, a multi-lamp type such as the above-mentioned chandelier, an insulator is added to a part of the conductor 28 that constitutes a feedback circuit via stray capacitance. 30 to intervene. As shown in FIG. 3, its specific configuration is as shown in FIG.
A gasket-like insulator 30 may be interposed between the support 25 and the support 25 provided at the upper center of the support. As the insulator 30, for example, a synthetic resin such as acrylic or phenol is used. When constructed in this manner, the relationship between the conductor 28 formed by the instrument member and the stray capacitance existing between the conductor 28 and the conductor 28 is as shown in FIG.

In the above configuration, the conductor 28 constituting the feedback circuit is connected to the instrument case 20 and the pillar 25 via stray capacitance.
There is no direct connection between the two and a feedback circuit is formed via the stray capacitance _C30 caused by the insulator 30. In other words, it becomes a feedback circuit with an intervening impedance (Z ₃₀ =1/2πNC ₃₀ ). Note that the above N is the noise frequency.
Although the floating capacitance C ₃₀ depends on the structure of the insulator 30, it can be made much smaller than the floating capacitances C ₂₁ and C ₂₅ described above.

Therefore, since a large impedance _Z30 is present in the high frequency noise feedback circuit via the stray capacitance, the amount of feedback becomes extremely small, and the high frequency noise generated in the power supply is reduced. According to the inventor's experiments, the noise was reduced from 65 dB to 55 dB by configuring as shown in FIG. However, the oscillation frequency of the inverter 16 is approximately 30KHz, and the discharge lamp 17
4 30W annular fluorescent lamps (FEC-30),
This is the case when the length of the post is 30cm.

Note that the location where the insulator 30 is provided is not limited to the above embodiment, and may be provided between the instrument case 20 and the arm 21, for example, as shown in FIG. The relationship between the conductor 28 and the stray capacitance existing between the instrument member and the conductor 28 in this case is shown in FIG.

Even with this configuration, there is a large impedance Z ₃₀ in the noise feedback circuit via stray capacitance.
Since this occurs, the amount of feedback can be reduced and high frequency noise generated in the power supply can be reduced.

Although the level of discharge lamps is relatively low not only when lit at high frequency but also when lit at commercial frequency, high frequency noise is generated when igniting and extinguishing every half cycle. It is also effective against objects.

As described above, according to the present invention, an insulator is interposed in a part of the noise feedback circuit via stray capacitance constituted by the fixture members, so that the shape of the lighting fixture can be reduced without changing the shape. Further, it is possible to reduce noise feedback via stray capacitance, which has been difficult in the past, without damaging the appearance, and noise disturbances can be prevented.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a discharge lamp lighting device in a lighting equipment, Fig. 2 is a sectional view showing the lighting equipment,
FIG. 3 is a sectional view showing an embodiment of the lighting device according to the present invention, and FIG. 4 is a circuit diagram showing a feedback circuit via stray capacitance in the lighting device shown in FIG.
FIG. 5 is a sectional view showing another embodiment of the present invention, and FIG.
This figure is a circuit diagram showing a feedback circuit via stray capacitance in the lighting fixture shown in FIG. 12... Discharge lamp lighting circuit, 14... High frequency noise prevention circuit, 17... Discharge lamp, 20... Instrument case, 21...
Arm, 22...Lamp, 23...Output line, 25...Strut, 26...Input line, 30...Insulator.

Claims (1)

[Scope of Claims] 1. A metal appliance case supported by a metal support and housing a discharge lamp lighting circuit including a high-frequency noise prevention circuit inside, and a metal appliance case equipped with a discharge lamp and directed outward from the appliance case. A lamp is held by a metal arm extending from the lamp, an input line is connected to the discharge lamp lighting circuit inside the appliance case through the support, and an input line is connected from the discharge lamp lighting circuit inside the appliance case to the inside of the arm. A lighting fixture comprising: an output line drawn out to the lighting fixture; and an electrical insulator interposed in at least a portion of a conductive path from the arm to the pillar via the fixture case. 2. The lighting device according to claim 1, wherein the electrical insulator is interposed at a connecting portion between the device case and the arm. 3. The lighting device according to claim 1 or 2, wherein the electrical insulator is interposed at a connecting portion between the device case and the support column. 4. The lighting fixture according to any one of claims 1 to 3, wherein the discharge lamp lighting circuit lights the discharge lamp at high frequency.