JPH0211995B2 - - 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. On the other hand, as a result of various studies, the present inventors have found that by applying a direct current bias to the lamp current of a discharge lamp to make the lamp current asymmetric between the positive and negative sides, the occurrence of flickering in brightness due to the above-mentioned striation can be substantially eliminated. We found that this can be prevented. The present invention was made based on the above discovery, and it solves the above-mentioned problem of striation, suppresses wasteful power consumption at room temperature, and also prevents cataphoresis caused by excessive DC bias and excessive electrode The purpose is to prevent lamp life from being shortened due to damage. [Structure of the Invention] (Means for Solving the Problems) The present invention makes the lamp current asymmetric between positive and negative by functioning an asymmetry means to apply a DC bias to the lamp current at low temperatures, and stops or stops the DC bias at room temperature. A structural feature is that it is provided with a symmetrization means that acts to reduce the amount of damage. The details of the present invention will be explained below with reference to FIG. Reference numeral 1 denotes a low-pressure mercury vapor discharge lamp such as a fluorescent lamp, which is energized from an AC power source 2 via a ballast 3. Note that in the present invention, the stabilizer 3 may be of any type. Reference numeral 4 denotes an asymmetrical means, which applies a DC bias to the lamp current with respect to the discharge lamp 1 to make the lamp current asymmetric between positive and negative. This asymmetrical means 4 is shown as a DC power source in the figure, and is connected in series to the AC power source 2. Symmetrization means 5 acts to stop or reduce the DC bias at room temperature. In the figure, this symmetrizing means includes a switch 6 connected to the asymmetrical means 4 with direct current, and a switch 7 capable of short-circuiting the asymmetrical means 4 and the switch 6.
It is shown as consisting of. The switch 6 is closed when the temperature is low, but the switch 7 is open, and the states of the switches 6 and 7 are reversed when the temperature is normal (for example, 15° C. or higher). (Operation) Next, the operation will be explained. When the temperature is low, the asymmetry means 4 functions to bias the lamp current of the discharge lamp 1 to DC. As a result, the lamp current becomes asymmetric between positive and negative, so although striations occur in the discharge lamp 1, the stripes move faster due to the DC electric field, and visually it appears that no striations have occurred. Therefore, flickering in brightness can be substantially prevented. At room temperature, the symmetrization means 5 acts to stop or reduce the DC bias. Since striation is generally less likely to occur at room temperature, there is no problem of striation. On the other hand, by stopping or reducing the DC bias, wasteful power consumption is suppressed, and the cataphoresis phenomenon that occurs when an excessive DC bias is applied and the ramp caused by damage to one electrode. Can prevent shortening of life. FIG. 2 shows another configuration of the present invention. This device differs from the one shown in FIG. 1 in that an asymmetric means 8 is provided in parallel with the discharge lamp 1. Note that "parallel" means allowing other means to intervene in between, and the term "series" is also the same. Also, as in Fig. 1, connect the discharge lamp 1 from the AC power source 2 to the ballast 3.
Lights up through. The desymmetrizing means 8 may be constituted by a series circuit of a DC power supply 10 and an impedance device 11. The symmetrizing means 12 is shown as a switch that is closed at low temperatures and opened at normal temperatures, and is connected in series to the desymmetrizing means 8. In the configuration shown in FIG. 2, the operation is similar to that in FIG. 1, so a description thereof will be omitted. FIG. 3 shows a specific embodiment of the present invention. Note that the same parts in the figure as in FIG. 1 are given the same reference numerals. 13 is a chiyoke coil as a stabilizer. In this embodiment, the desymmetrizing means consists of a diode. Further, the symmetrization means includes a nonlinear resistance element 15 having negative temperature/resistance characteristics and whose resistance value changes suddenly at room temperature, for example, around 15°C. This resistive element 15, ie the symmetrizing means, is connected in parallel to the diode 14, ie the desymmetrizing means. Next, the operation of the third illustrated embodiment will be explained. When the voltage of the AC power supply 2 has the same polarity as the diode 14, a half-wave lamp current is supplied to the discharge lamp 1 via the diode 14. On the other hand, although a lamp current with positive and negative symmetry tends to flow through the nonlinear resistance element 15, the nonlinear resistance element 15 is short-circuited by the diode 14 in the half wave that is the forward direction of the diode 14. On the other hand, in the half wave in the opposite direction of the diode 14, the resistive element 15
Lamp current flows through. When the temperature is low, the resistance of the resistor element 15 is large, and therefore the lamp current at this time is smaller than the other half-wave current flowing through the diode. That is, when the temperature is low, the asymmetry means functions and the lamp current becomes asymmetric between the positive and negative sides as shown in FIG. In conjunction with this, flickering of brightness due to striation of the discharge lamp 1 can be substantially prevented for the above-mentioned reason. Next, at room temperature, the nonlinear resistance element 15
Since its resistance is small, is there no difference in the lamp current flowing through the resistor element 15 during the half-wave in the opposite direction of the diode 14 compared to the lamp current flowing through the diode 15 during the other half-waves? , relatively less. That is, the lamp current is made symmetrical in positive and negative directions, and the desired improvement is achieved as described above. In addition, in the case where the non-linear resistance element 15 is used to make the lamp current asymmetrical by the diode 14 symmetrical as in this embodiment, the power loss of the non-linear resistance element 15 at room temperature is reduced. is smaller than that at low temperatures, so wasteful power consumption at room temperature can be reduced. Note that, as mentioned above, striations are less likely to occur at room temperature, so there is no problem even if the asymmetry of the lamp current is reduced at room temperature. Further, in the case of this embodiment, it is preferable that the non-linear resistance element 15 has an extremely small resistance at room temperature, but the object of the present invention is not limited to this, even if it shows a certain resistance value. It's achievable, so I don't mind. Furthermore, by connecting a small resistance in series with the diode 14, it is possible to further improve the symmetry of the lamp current at room temperature. Furthermore, other impedance elements may be provided in series and/or in parallel with the nonlinear resistance element 15, if necessary. Next, the experimental results are shown. (Experiment 1) In the configuration shown in Figure 3, output frequency of AC power supply 2: 45KHz Discharge lamp 1: 40W fluorescent lamp (FLR40S manufactured by Toshiba/
Using M/37 "Product name Watto Brighter", filled with argon and krypton, tube diameter 32 mm, 20 lamps were started with different ratios A/B of the positive (A) and negative (B) values of the lamp current. The results of lighting were as shown in the table below and Figures 11 and 12 A. In both cases, the ambient temperature was 5°C, and the lamp current value (effective value) was 0.34A. Also. In FIG. 11, the horizontal axis is the positive/negative ratio A/B of the lamp current value, and the vertical axis is the flicker occurrence rate due to striation. Furthermore, in FIG. 12, the horizontal axis is the above A/
B, and the vertical axis is the time required for the flickering due to striation to disappear. In FIGS. 11 and 12, the horizontal axis is on a logarithmic scale.

[Table] As shown in the above table and Figures 11 and 12, the ratio of lamp current value A/
By setting B to 1.001 or more, it was possible to reduce the occurrence rate of flicker due to striation, and also to shorten the time it took for this flicker to disappear. In particular, when the ratio is 1.01 or more, it is even more effective, as is clear from FIGS. 11 and 12. In addition, the ambient temperature of the discharge lamp used in this experiment was 15℃~
At temperatures above 18°C, striations did not occur visually. Therefore, by using a non-linear resistance element 15 that is compatible with discharge lamps and whose resistance value rapidly decreases at 15°C to 18°C, it is possible to stop or reduce unnecessary DC bias at room temperature. did it. (Experiment 2) Discharge lamp 1: 110W fluorescent lamp (manufactured by Toshiba)
FLR110H/A) argon-filled tubes with a diameter of 38 mm were started and lit in the same manner as above, with 20 tubes at a time.The results are shown in the table below and Figures 11 and 12 B. In addition, the lamp current value (effective value) is
0.58A, and the others are the same as in Experiment 1.

[Table] In this experiment as well, by setting the ratio A/B of positive and negative values of the lamp current to 1.001 or more by applying a DC bias, it was possible to reduce the flicker occurrence rate due to striation, and this flicker could be reduced. It also shortened the time it took for it to disappear. Furthermore, the discharge lamp used in this experiment did not visually cause striations when the ambient temperature was 10°C or higher. Therefore,
By using a nonlinear resistance element 15 whose resistance value decreases rapidly at 10° C., unnecessary DC bias at room temperature can be stopped or reduced. (Experiment 3) Discharge lamp 2: 40W fluorescent lamp (Toshiba FLR40S/
M) The lamp was started and turned on in the same manner as above using argon enclosure and a tube diameter of 32 mm, and the results were almost the same as in the case of the 110W fluorescent lamp described above. FIG. 5 to FIG. 7 are for explaining still other embodiments of the present invention, each showing only the main parts. In the embodiment shown in FIG. 5, the desymmetrizing means 16 is mainly constituted by a parallel circuit of a diode 17 and a resistor 18, and the symmetrizing means 19 includes a transistor 20 connected in parallel to the desymmetrizing means 16 and The main component is a non-linear resistance element 21 having positive temperature/resistance characteristics connected between the base and emitter of 20. The other configurations are the same as those of the present invention described above. In this embodiment, when the temperature is low, the transistor 20
is off, and the transistor 20 is on at room temperature. Therefore, at low temperatures, substantially only the asymmetrical means function, so that the lamp current is DC-biased and symmetrical. Furthermore, at room temperature, the symmetrizing means functions in cooperation with the asymmetrical means, so the DC bias disappears and the lamp current becomes symmetrical. The embodiment of FIG. 6 is substantially similar to the embodiment of FIG.
The main component is a nonlinear resistance element 22 with a negative characteristic connected between the collector and base of this transistor. The operation and features of this embodiment are almost the same as those of the embodiment shown in FIG. In the embodiment of FIG. 7, the symmetrization means 24 consist of a thermal switch connected in parallel with the desymmetrization means 16. It will be easily understood that this embodiment is essentially the same as the previously described embodiments. FIGS. 8 and 9 show still other embodiments of the present invention. The same parts as in FIG. 2 are given the same reference numerals. In FIG. 8, the asymmetry means 30 is composed of a step-down transformer and a rectifier, and supplies a low-voltage DC voltage to the discharge lamp 1 in parallel with the output of the ballast 3 from the AC power supply 2, thereby controlling the lamp current. This makes it asymmetrical. On the other hand, the symmetrizing means 31 is a switch that controls the output of the asymmetrizing means 30 according to the temperature as described above. In this embodiment, as the symmetrizing means 31, the symmetrizing means shown in FIGS. 5 to 7 can be used with the temperature characteristics reversed. Furthermore, it will be readily understood that other configurations can be used without being limited to these. In the embodiment shown in FIG. 9, the asymmetry means 32 connected in parallel with the discharge lamp 1 is constructed with a series circuit of a diode 38 and a capacitor 34, and an impedance element 35 connected in parallel to the diode 33 as main parts. be. The symmetrization means 36 is a switch that opens at room temperature, and is provided in series with the capacitor 34. This symmetrization means 36 may also be constructed similarly to that of FIG. Furthermore, the impedance element 35 may be a nonlinear resistance element with negative characteristics. Since the operation of this embodiment can be easily understood from the above explanation, the explanation will be omitted. Note that the present invention is not limited to the above-mentioned embodiments, and for example, the AC power source for lighting a low-pressure mercury vapor discharge lamp may output high-frequency AC of several KHz to several hundred KHz. In this case, it can be easily realized by using an inverter or the like as shown in FIG.
Further, the output waveform of the AC power source is not limited to a sine wave, but may be a rectangular wave or the like. Furthermore, the desymmetrization means
It will be easily understood that any configuration may be used as long as it makes the lamp current of the discharge lamp asymmetrical in positive and negative polarity by DC biasing it. Of course, when using diodes as the asymmetric means, it goes without saying that a plurality of diodes may be connected in series. Furthermore, it will be readily understood that the symmetrization means may have any configuration as long as it stops or reduces the bias. Also,
In the present invention, the criteria for low temperature and normal temperature are relative, and the temperature range may differ depending on the discharge lamp. For example, in the case of an energy-saving fluorescent lamp containing krypton (Toshiba's "Watto Brighter"), striations are less likely to occur at temperatures above 15°C;
Striation becomes less likely to occur above ~10°C. Therefore, the standards for low temperature and room temperature are determined in consideration of such characteristics of the discharge lamp. [Effects of the Invention] As described in detail above, the present invention includes an asymmetrical means for making the lamp current asymmetric between positive and negative by applying a DC bias, and the asymmetrical means is made to function at low temperatures, and the DC bias is stopped or canceled at room temperature. Since it is equipped with a symmetrization means that acts to reduce the brightness, flickering of brightness due to striation can be substantially prevented at low temperatures where striation is likely to occur, as well as at room temperature where striation is less likely to occur. By eliminating sometimes unnecessary lamp current asymmetry,
It is possible to prevent wasteful power consumption, occurrence of cataphoresis, and shortened lamp life due to excessive damage to the electrodes.

[Brief explanation of drawings]

1 and 2 are circuit diagrams showing different configurations of the present invention, FIG. 3 is a circuit diagram showing a specific embodiment, FIG. 4 is a lamp current waveform diagram explaining the operation of FIG. 3, and FIG. Figures 5 to 7 are main circuit diagrams showing other embodiments, Figures 8 to 10 are circuit diagrams showing still other embodiments, and Figures 11 and 12 are curve diagrams showing experimental results. It is. 1...Low pressure mercury vapor discharge lamp, 4, 8, 16, 3
0,32...Asymmetry means, 5,12,19,1
9', 24, 31, 36... Symmetrization means.

Claims (1)

[Scope of Claims] 1. A low-pressure mercury vapor discharge lamp that is operated with alternating current; Asymmetrical means for making the lamp current of this discharge lamp positive and negative asymmetrical by biasing it to direct current; The asymmetricalizing means is made to function at low temperatures. A discharge lamp lighting device comprising: a symmetrization means that acts to stop or reduce the DC bias at room temperature; 2. The desymmetrization means is connected in series with the low-pressure mercury vapor discharge lamp; The symmetrization means is connected in parallel with the desymmetrization means. The discharge lamp lighting device described. 3. The desymmetrization means is connected in parallel to the low-pressure mercury vapor discharge lamp; The symmetrization means is connected in series with the desymmetrization means. A discharge lamp lighting device according to scope 1. 4. The radiation source according to claim 2, characterized in that the desymmetrizing means is composed of a diode; the main part of the symmetrizing means is composed of a nonlinear resistance element whose temperature/resistance characteristics are negative. Electric light lighting device. 5. The asymmetry means includes a diode as a main part; 3. The discharge lamp lighting device according to claim 2, wherein the discharge lamp lighting device includes a non-linear resistance element having a characteristic. 6. The discharge lamp lighting device according to claim 3, wherein the asymmetry means comprises a switch that is closed at low temperatures and opened at normal temperatures.