KR840002365B1 - Fluorescent lamp with reduced electromagnetic interference - Google Patents

Abstract

The electromagnetic interference produced by arc discharge lamps particularly fluorescent lamps operating at frequencies in excess of 15,000 Hz, is reduced by providing a current path external to the envelope containing the discharge. The current flow in the path is oriented so as to produce a magnetic field generally in opposition to the magnetic field generated by the current in the arc discharge. The present arrangement is partic. applicable to circular fluorescent lamps with a centrally disposed ballast operating at relatively high frequencies.

Description

Fluorescent lamps with reduced electromagnetic interference

1 is a perspective view of a circular fluorescent lamp with a ballast centered and inserted into a conventional incandescent lamp socket.

2 is a schematic diagram illustrating one embodiment of the invention in which a current cancellation loop is disposed along the back envelope.

3 is a schematic diagram showing another embodiment of the present invention in which the diameter of the offset loop is smaller than the discharge current loop and the difference in size is compensated for by the current transformer.

4 is a schematic diagram showing another embodiment of the present invention in which the difference in the current loop diameter is supplemented by an increase in the number of turns of the offset loop.

FIG. 5 is a view similar to FIG. 4 with an offset loop associated with each filament.

6 is a schematic diagram of the present invention in which the offset loops consist of multiple spirals.

FIG. 7 shows an embodiment of the invention in which the starter switch is in series with a filament such as the back. FIG.

8 is a schematic diagram showing one embodiment of the present invention that can be used for linear fluorescent lamps.

9 is a schematic diagram showing an embodiment of the present invention that can be used for linear fluorescence and the like at high voltage.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to arc discharge lamps, such as fluorescent lamps operating at relatively high frequencies, and more particularly to circular fluorescent lamps in which a ballast is disposed at the center. '

The economic demand for saving electrical energy has made it desirable to increase the efficiency of electric lighting devices these days. In particular, it has become desirable to replace fluorescent bulbs with an efficiency of approximately 15 tomen per watt with fluorescent lamp devices with as high efficiency as possible. Current fluorescent devices operate at an efficiency of approximately 40 tons per watt or more. However, due to the characteristics of arc discharge and the like, there is a problem that a special power source is required for the fluorescent lamp. Such power circuits are called ballasts in this technology. These ballasts are common to fluorescent lamp technology and provide different levels of power due to the difference in lamp characteristics during the time of the lamp and during normal operation.

In some fluorescent lamps, the view point is facilitated by using a filament heated by a separate circuit in the ballast.

Such lamps use two conductors between each end of the lamp and the ballast. These are known as quick start lamps.

In another lamp, one current source is first used to heat the filament and then switched to discharge power. This switching action is accomplished by a manually operated switch known as a starter or by an automatic, glow discharge heat switch.

These lamps use one conductor between each part of the lamp and the ballast, and one conductor between the switch, such as each end of the lamp and the point of view. These are known as switch start lamps. In the third type of lamp, the point of view and the like are made by supplying a high voltage causing a discharge between the electrodes arranged at both ends of the lamp.

Such lamps use one conductor between each end of the lamp and the ballast. These are known as instant start lamps.

Recently, it has been concluded that if the lamp is operated at frequencies above 15,000 hetz, the weight and material of the ballast is reduced.

Such operation has also been found to increase the efficiency of the lamp.

However, it is also known that lamps operating at such high frequencies, that is, operating at more than 15,000 hertz, can cause electromagnetic interference that can disturb radio and television reception. If the fundamental frequency of the electronic inverting ballast lies in the AM broadcast band (535KHz-1605KHz) mill, the most serious disturbance problem is caused by the magnetic field generated by the lamp / ballast system. Electric fields are not a problem for disturbance problems because AM radio receivers commonly used in homes are designed to respond to magnetic field components of electromagnetic waves and are relatively insensitive to electric field components.

The magnetic field is generated by the current flowing in the conductor and in particular in the application intended in the present invention, the magnetic field is generated in the current flowing in the discharge lamp itself.

The intensity of the magnetic field generated is proportional to the product of the current through the circuit and the area of the current loop. This amount is commonly called magnetic moment.

The occurrence of magnetic disturbances is generally controlled in a number of ways. For example, a conductive shield can be placed around the current loop. As such, electromagnetic interference generated in the ballast itself can be easily controlled by using a conductive shield device. However, shielding the lamp itself is quite difficult because it requires the use of a high photoconductive material as well as high electrical conductivity. Another way to control electromagnetic interference is to filter out the ballast output waveform to remove frequency components in the AM frequency band. Most electronic ballasts have a fundamental frequency of less than 535 KHz, but are disturbed by harmonics of the fundamental waves generated by the ballast or lamps and by the current loops in the lamp envelope.

Moreover, usually high efficiency inverters generate an output waveform containing these undesirable harmonics.

These disturbing harmonics may be filtered out of the ballast waveform before being fed into the lamp, but such filters usually consume power, are physically large, and expensive.

According to an embodiment of the present invention, an arc discharge device includes an elongated vacuum envelope, an electrode disposed at both ends thereof, and a discharge medium capable of being ionized therein.

This discharge device is operated by energizing alternating current in opposite directions between the electrodes.

SUMMARY OF THE INVENTION The present invention provides a lamp envelope with an electron emission reduction window including a current path for flowing a current in a direction opposite to the current direction of discharge in the shell to generate a magnetic field opposite to the magnetic field generated by the discharge. .

The present invention is particularly used in fluorescent discharge lamps that form passages in which the discharge arc itself closes, such as in circular fluorescent lamps.

The offset magnetic field is generated by a current loop made such that the offset magnetic field, which is coplanar with the lamp, is 180 degrees out of phase with the magnetic field generated by the discharge. The offset loop has a magnetic moment that is approximately equal to the discharge current loop to offset the disturbing magnetic field as much as possible. Although the present invention is most suitable for circular fluorescent lamps, it can be used for more general linear fluorescent lamps and also for other arc discharge devices operating at frequencies above approximately 15,000 Hertz.

It is therefore an object of the present invention to provide an efficient fluorescent light source operating at a relatively high frequency at which electromagnetic interference is reduced to a significantly low level.

1 shows a fluorescent lamp of the kind to which the present invention is particularly applicable.

In this lamp, an ionizable discharge medium 18 such as a mercury vapor and a burning gas such as argon is contained in a discharge shell 10 made of glass coated with an ultraviolet phosphor.

Within and both ends thereof are electrodes 15 and 16 (not shown) through which discharge current flows.

This lamp shell 10 is supported by a spider lag 11 which is preferably made of a light plastic material which is slightly heat resistant.

The spider lag 11 is fixed to the central hub in which the ballast 12 is built, which can be dropped by operating the slide switch 14.

The slide switch 14 is placed on the spider lag 11, which includes a lead wire connecting the ballast 12 to the lamp electrodes 15 and 16.

This ballast also has a conventional threaded base 13 that can be fitted into a conventional incandescent lamp receptacle.

In this way, the ballast converts 60 cycle alternating current or alternating current of black or other frequency into alternating current of 15,000 hertz or more to power the lamp itself.

The alternating discharge passing through the ionization medium 18 serves to emit ultraviolet light impinging on the phosphorus 17 (shown in FIG. 2) covering the outer wall of the shell. It is due to the excitation of this phosphorus that becomes visible light.

2 shows one embodiment of the invention in which an offset loop is arranged in the ridge of the lamp.

Also shown in FIG. 2 is an intermediate arc discharge passage 19 shown in dashed lines. In this embodiment, the diameter of the offset coil is selected to be equal to the diameter of the discharge passage.

A lead connected to the filament 15 is disposed along the outer surface of the discharge shell 10. During normal operation of the discharge lamp, the current in the offset loop 20 flows in a direction that is usually opposite to the direction of the current in the discharge passage. This reverse current generates a magnetic moment that is about the same size as the magnetic moment generated by the current in the discharge shell but is reversed in direction.

In this way, the electromagnetic interference generated by the high frequency operation of the lamp is considerably reduced.

2 shows a rapid start lamp in which two conductors at each end of the lamp are connected to the ballast.

Part of the discharge current flowing to or from one end of the lamp flows through one of the conductors attached to that end of the lamp and the remaining discharge current flowing to the end of the lamp passes the other conductor attached to the same end of the lamp. As it flows through, the offset loops are formed in pairs by two conductors from one end of the gram. The pair of conductors constitute a single winding offset loop.

If a quick start or switch start lamp is used. The offset loop is formed by one of the conductors connected between the ballast and one end of the lamp. One embodiment of the invention for use in a switch start lamp is described later with reference to FIG.

The conductive offset loop leads themselves are provided in one of several ways. For example, if the coating has a sufficiently low resistance, the coating itself on the glass becomes the offset loop lead. Its electrical coating becomes transparent.

For example, tin oxide or an alloy of indium and tin oxide can be used in certain lamp conditions.

Alternatively, the lead may be provided by a conductive tape adhered to the wall of the shell.

The leads forming the canceling loop may be wound spirally around the lamp envelope itself. If conductive coatings are used, wide coatings that take up a large portion of the glass surface will more effectively offset than narrow coatings.

If conductive coatings are used with switch start or instant start lamps that require only one color offset loop, conductive coatings covering almost the entire front of the lamp are preferred. This cancels the magnetic field most closely to the lamp field.

The offset conductor 20 flows approximately 0.6 amps of current during normal operation. Insulation of these conductors should reduce the risk of impact.

In FIG. 2 it can also be seen that the conductive leads from the filaments 15 and 16 go through the ballast hub as shown in FIG. 1 towards the center of the lamp.

In particular, the leads leading to the ballast are guided along the spider lag 11 of FIG. However, the present invention can also be used for ballasts in which the center of the lamp lies in a position other than that.

3 shows another embodiment of the invention in which the offset loop has a diameter Dc smaller than the diameter of the arc discharge passage D _L. However, as can be seen from the definition of the magnetic moment given above, this embodiment does not automatically cancel due to the difference in the loop passage area. However, the offset loop 22 is coupled with the winding through the current transformer 23 as shown.

The winding ratio of the primary winding wave secondary winding is adjusted according to the following equation.

(1)

(One)

As long as the turns ratio shown in FIG. 3 is selected according to the above equation, the offset of the magnetic moment is made.

In particular, in the present invention, it is preferable to design the Dc value so that the offset current loop is completely contained in the ballast hub 10 that also includes the current transformer 23.

However, for the sake of clarity, the physical location of the part is not shown since the third is essentially schematic. Alternatively, Dc may be selected to place the offset loops along the inner diameter of the discharge envelope 10, in which case the offset loops serve as an auxiliary (ground plate) required for effectively initiating the discharge of the rapid star drape. Can be made.

Not only do the compensators compensate for the relatively small difference in the current loop area according to Equation 1, but they also allow the offset loop to be connected to a voltage source or circuit common point in the ballast designed to supply a relatively high potential between the offset loop and the electrodes 15, 16. Electrically isolated between the lamp electrode wave canceling loops.

Supplying such a potential does not affect the flow of current through the loop and therefore does not change the magnetic field generated by the cancellation loop. 、

If instant start or Swiss start lamps are used, the current transformer can also be used with offset loops in which only one primary winding has a large diameter Dc from one end of the lamp.

The turns ratio of the primary winding and the secondary winding of the facet machine 23 is adjusted again with the help of Equation 1 described above.

4 shows another embodiment of the invention in which the diameter of the offset loop is smaller than the diameter of the discharge loop, ie, D _L is smaller than this. However, by increasing the number of turns of the offset loop, the offset of the magnetic moment becomes easy.

In particular, in order to achieve optimum cancellation in the embodiment of Fig. 4, the important design parameters become the following relationship.

(2)

(2)

Where N is the number of turns of the offset loop. 4 is especially the case where N is two. When metal start lamps are used, each of the two conductors connected to a particular filament has a discharge current portion.

Therefore, conductors are taken in pairs when constructing an offset loop. In equation (2), the number of turns N is determined in this case by counting the number of turns on the conductor.

FIG. 5 shows the embodiment of the present invention which is the same as that shown in FIG. 4 except that a cancellation current loop is provided in each circuit of the electrodes 15 and 16.

Equation (2) can also be applied to the embodiment of FIG. 5, which is also the case where N is equal to 2.

In the present invention, a circular current loop is used to cancel the magnetic field generated by the discharge current, but other forms of offset loops may be used for the same purpose. In particular, FIG. 6 shows the symmetric helical shape of the offset loop conductor 28, which serves to effectively reduce electromagnetic interference.

7 shows another embodiment of the invention in which switch start fluorescent lamps are used. The start 31 is connected between the filaments 15 and 16. In this particular embodiment, a single offset loop lead 30 is used.

FIG. 7 also explains that a significant amount of electromagnetic interference is eliminated by placing the offset loops along the inner diameter of the discharge shell. Although magnetic moment offsets are not accurate, the desired level of illumination is attained almost without obstruction.

8 and 9 show the use of the offset current conductors 32 and 34 of the present invention in a conventional linear fluorescent lamp structure.

The basic difference between the embodiments shown in FIGS. 8 and 9 is that the lamp shown in FIG. 8 is a quick start lamp and that of FIG. 9 is a instant start lamp. In these embodiments the offset conductors are wound spirally around the lamp and may be conductive coating as described with reference to FIG. 2.

In the embodiment of the present invention shown in Figures 2 and 7 it is preferred that the offset loop conductors 20 and 30 are fixed to the discharge shell 10, respectively.

In the embodiment shown in Figs. 4 and 5, the offset loops 24 and 26 are each chosen to be of sufficient diameter so as to be completely enclosed in or at least nearly in the ballast hub 10, respectively.

From the foregoing, it will be appreciated by the present invention that the fluorescent lamp structure is operated efficiently at the relatively high frequency of alternating current without the incidental problem of electromagnetic radiation interference. The object of the present invention can be made with minor design changes and can be easily made.

Claims (1)

Electrodes 15 and 16 are disposed at both ends and include a hollow shell 10 and an electron emission reduction device in which a discharge medium 18 is enclosed, and an alternating current flows through the medium between the electrodes to operate. In the discharge lamp which becomes, Arc discharge lamp, characterized in that the current path is provided in the shell so that the reduction device (20) generates an offset magnetic field to cancel the magnetic field generated by the discharge current flowing between the electrodes (15, 16).

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