JPH0128480B2 - - Google Patents

Description

[Detailed description of the invention]

[Object of the Invention] (Industrial Application Field) The present invention relates to a lighting device for a low-pressure mercury vapor discharge lamp such as a fluorescent lamp. (Prior art) When a low-pressure mercury vapor discharge lamp containing an inert gas with a large atomic weight such as argon or krypton, such as a fluorescent lamp or a germicidal lamp, is lit with alternating current at low temperatures, a striped pattern appears on the tube wall. It is known that a phenomenon (hereinafter referred to as striation) is likely to occur. (Problems to be Solved by the Invention) Although the mechanism by which this striation occurs is not detailed, it sometimes continues throughout the lighting period and causes discomfort such as flickering of brightness. In contrast, the present inventors first applied a DC bias to the lamp current of the discharge lamp to make the lamp current asymmetric between positive and negative, thereby substantially preventing the flickering of brightness associated with the above-mentioned striation. I found out what I can do. That is, it has been found that the problem of striation can be substantially solved by setting the ratio of positive and negative values (effective values) of the lamp current to 1.001 or more. This will be described in detail below based on experimental results. First of all, we used a 40W fluorescent lamp (FLR40S/M/37 made by Toshiba "Watto Brighter") as a discharge lamp: filled with argon and krypton, tube diameter 32
The results of starting and lighting 20 lamps each with different ratios A/B of positive (A) and negative (B) lamp current values of mm) are shown in the table below and curve A in Figures 5 and 6. show. In addition,
In both cases, the ambient temperature is 5°C, the lamp current value (effective value) is 0.34A, and the lighting frequency is 45KHz.

[Table] Second, a 110W fluorescent lamp (Toshiba FLR110H/A: argon filled, tube diameter 38mm) is used as a discharge lamp.
The results of starting and lighting the lamp in the same manner as above are shown in the table below and curves B in Figures 5 and 6. In addition, the lamp current value (effective value) is 0.58A in all cases, and the others are 1st
This is the same as in the experiment.

[Structure of the invention]

(Means for Solving the Problems) The present invention provides positive/negative asymmetry means consisting of a series circuit of a rectifying element and an inductor in parallel to a discharge lamp that is lit with alternating current. A structural feature of the discharge lamp is that the lamp current of the discharge lamp is DC biased. The details of the present invention will be explained below with reference to FIG. 1a and 1b are low-pressure mercury vapor discharge lamps such as fluorescent lamps, which are connected in series with each other in FIG. 2 is an AC power supply device, for example, a commercial AC power supply 3, a rectifier 4 that rectifies the output of the commercial AC power supply 3, and a rectifier 4 that rectifies the output of the rectifier 4 from 20KHz.
It consists of a high frequency generator 5 consisting of an inverter etc. that converts into high frequency alternating current of 100KHz, and an output transformer 6. Note that when a leakage type transformer is used as the output transformer 6, the leakage inductance can be used as a current limiting device for the discharge lamps 1a and 1b. Reference numeral 7 denotes an asymmetrical means consisting of a series circuit of a rectifying element 8 and an inductor 9, and is provided in parallel with at least one of the discharge lamps 1a and 1b. Here, parallel means
This means that, for example, a resistor or the like may be inserted in series between the discharge lamp 1a and the asymmetrical means 7. Note that in the present invention, a resistor or the like may be connected between the rectifying element 8 and the inductor 9. In FIG. 1, another discharge lamp 1 which is not provided with the asymmetrical means 7
A starting capacitor 10 is connected in parallel to b. (Operation) Next, the operation will be explained. First, to explain the operation, let us explain about Fig. 2. Fig. 2 A shows the lamp current waveform of the discharge lamp 1a, Fig. 2 B shows the lamp current waveform of the discharge lamp 1b, and Fig. 2 C shows the asymmetrical lamp current waveform. These are current waveforms of the inductor 9 of the means 7, and the positive direction is on the side of point a in FIG. 1, respectively. Also,
Parts of FIG. 2 are enlarged and simplified for ease of understanding. In FIG. 1, when point a is positive, current flows through the path from point a to discharge lamp 1b to discharge lamp 1a series circuit 7 to point b, and for discharge lamp 1a, the lamp current is asymmetrical means 7 It will be divided into Therefore, in this polarity, as is clear from FIG. 2, the lamp current value of the discharge lamp 1a is smaller than the lamp current value of the discharge lamp 1b.
Next, when the point b side is positive, point b → discharge lamp 1
A current flows along the path from point a to discharge lamp 1b to point a, and the inductor 9 stored when the polarity is
Due to the discharge, a current flows from the inductor 9 to the rectifying element 8 to the discharge lamp 1a to the inductor 9. Therefore, at this time, more lamp current is flowing through the discharge lamp 1a than in the previous polarity. Also, at this time, a smaller lamp current flows through the discharge lamp 1b than in the previous polarity. In other words, comparing when point a is positive and when point b is positive, when point b is positive, inductor 9 is not inserted in parallel with discharge lamp 1a, and the total Load impedance increases. Therefore, the AC power supply device 2
The positive and negative current values of the output current become asymmetrical. As described above, the discharge lamps 1a and 1b are biased with direct current due to the presence of the asymmetrical means 7, and the positive and negative current values of the lamp currents become asymmetrical. As a result, even if striation occurs in the discharge lamps 1a and 1b,
The DC electric field speeds up the movement of the stripes, making it visually equivalent to no striations, and therefore flickering in brightness can be substantially prevented. Furthermore, since the current flowing through the inductor 9 has a phase lag of 90° with respect to the voltage, this inductor 9
The power loss due to this is extremely small. Since the other functions are easily understood, their explanation will be omitted. Next, the experimental results will be shown. Discharge lamps 1a, 1b: Toshiba fluorescent lamps (product name Watto Brighter) FLR-40S/M/37 AC power supply 3: 200V, 50Hz High frequency generator 5 input voltage: Average value 220V Ripple rate (highest value - lowest value / average Value): 60% Lighting frequency: 43KHz Inductor 9: 16.4mH Starting capacitor: 1000pF When the current flowing through inductor 9 is 21mA,
The current from point b to point a of the discharge lamp 1a was 148.3 mA. Note that all current values are average values. In addition, neither of the discharge lamps 1a and 1b suffered from striation, nor did they suffer from problems of cataphoresis and life deterioration. (Example) Next, an example of the present invention will be described with reference to FIG. Note that FIG. 3 shows only the main parts, and other parts are omitted because they are the same as in FIG. 1. In this embodiment, the desymmetrizing means 7' is provided in parallel to the discharge lamps 1a, 1b which are connected in series. Further, a resistor 20 or the like may be appropriately provided in series with the asymmetrical means 7'. However, since the provision of the resistor 20 increases power loss, it is necessary to select the resistance value so that the power loss is within an allowable range. In this embodiment, the discharge lamps 1a, 1
b, the current value of the half wave of the same polarity is larger than the current value of the other polarity. Other functions are the same as those in FIG. 1, so explanations will be omitted. FIG. 4 shows yet another embodiment.
In FIG. 4, only the main parts similar to those in FIG. 3 are shown. In this embodiment, the discharge lamps 1a and 1b are connected in parallel with each other, and the asymmetry means 7'' is provided in parallel with these discharge lamps 1a and 1b.In this embodiment as well, the asymmetry means 7'' is provided with a resistor. etc. may be provided. Further, although not shown in the drawings, each of the discharge lamps 1a and 1b may be provided with a balance transformer, if necessary. In this embodiment, as in the embodiment of FIG. 3, the current values of the discharge lamps 1a and 1b at the same polarity are equal. Regarding other effects, please refer to the 3rd section.
Similar to the illustrated embodiment, the description will be omitted. Note that the present invention is not limited to the above embodiments. For example, the AC power supply device that energizes the discharge lamp may be a low frequency power source such as a commercial power source, and the output waveform may be a sine wave, a rectangular wave, or the like. In such a case, a well-known current limiting device can be used. Furthermore, the rectifying element of the asymmetrical means may be a transistor, a Zener diode, or the like in addition to a diode. Furthermore, when a resistor or the like is connected in series to the asymmetrical means as shown in Fig. 3,
A non-linear resistance element may also be used. This case is advantageous in that the current can be suppressed to prevent an increase in power loss in the event of an abnormality in which an overcurrent is about to flow through the asymmetry means. Furthermore, the number of discharge lamps may be one or three or more, and the asymmetric means may be provided in parallel for each discharge lamp, or the asymmetric means may be provided for each discharge lamp of a plurality of discharge lamps connected in series. In this case, the polarity of the rectifying element of the asymmetric means may be reversed. [Effects of the Invention] As described above, the present invention consists of a series circuit of a rectifying element and an inductor, and is provided in parallel to a low-pressure mercury vapor discharge lamp that is lit with AC, and converts the lamp current of the discharge lamp into DC. Since it is equipped with an asymmetrical means that applies a bias to make the positive and negative asymmetries, even if the discharge lamp causes striation, it is possible to substantially prevent brightness from flickering due to this striation, and furthermore, the power loss in the inductor can be reduced. It is extremely small in number and has an extremely simple configuration.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the configuration of the present invention, FIG. 2 is a waveform diagram showing the operation of FIG. 1, and FIGS. 3 and 4 are circuit diagrams showing only the main parts of different embodiments. Figure 5 is a curve diagram showing the relationship between the ratio of making the lamp current asymmetric between the positive and negative sides and the incidence of striations, and Figure 6 is the relationship between the ratio of making the lamp current asymmetric between the positive and negative sides and the time required for striations to disappear. FIG. 1... Low pressure mercury vapor discharge lamp, 2... AC power supply device, 7, 7', 7''... Asymmetry means.

Claims (1)

[Claims] 1. A low-pressure mercury vapor discharge lamp that is lit with alternating current; consisting of a series circuit of a rectifying element and an inductor, which is provided in parallel to the discharge lamp and biases the lamp current of the discharge lamp to direct current. A discharge lamp lighting device characterized by comprising: an asymmetrical means for making the positive and negative asymmetrical; 2. The low pressure mercury vapor discharge lamp has a power rating of 20KHz to 100K.
The discharge lamp lighting device according to claim 1, wherein the discharge lamp lighting device is lit by a Hz AC power source. 3. A patent claim characterized in that a plurality of the low-pressure mercury vapor discharge lamps are connected in series; and the asymmetry means is provided in parallel with one of the plurality of discharge lamps. The discharge lamp lighting device according to Range 1 or 2.