JPH0334876Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention relates to a discharge lamp lighting device, particularly a rabbit start type discharge lamp lighting device that lights two 40W fluorescent lamps in series.

(Prior Art) In this type of discharge lamp lighting device, a configuration using a ballast consisting of a leakage transformer in which a primary coil is connected to a commercial AC power source and a secondary coil is connected in series with the primary coil is well known. It is being This type of leakage transformer has a structure in which a bridge gap is provided in the center leg of the iron core. This is to generate more harmonic voltage so that the lamp voltage approaches a trapezoidal wave, and the closer the lamp voltage approaches a trapezoidal wave, the more compact the ballast and phase advance capacitor can be. .

However, if the bridge gap is increased to increase the amount of harmonics generated in order to bring the lamp voltage closer to a trapezoidal wave, the lamp tends to flicker when lit, especially when lit in low temperature conditions. For this reason, it was believed that there was a limit to the miniaturization of ballasts and phase advance capacitors by increasing the bridge gap.

(Means for solving the problem) The purpose of this invention is to reduce the size of the ballast and phase advance capacitor without increasing the bridge gap.

(Problem that the invention aims to solve) This invention provides an intermediate tap in the primary coil of the leakage transformer at a point where a voltage of 70V or more and less than 100V is generated, and connects the secondary coil to this intermediate tap. It is characterized by

(Function) With this connection, when lighting, the voltage at the intermediate tap in the primary coil and the voltage at the
The voltage added to the voltage at the part where the primary and secondary coils are connected is the same as the lamp voltage, and the voltage added to the voltage at the part where the primary and secondary coils are connected is the same as the lamp voltage. will also be lower. This reduces the voltages applied to both the leakage transformer and the phase advance capacitor. Therefore, the volt-ampere required for the leakage transformer can be reduced, and a capacitor with a low withstand voltage can be used as the phase advance capacitor.

(Example) An example of this invention will be described with reference to the drawings. 1st
In the figure, 1 is a commercial AC power supply, 2 is a ballast consisting of a leakage transformer, and as shown in the cross section of FIG. and a secondary coil 6. 7 is a bridge gap formed on the central leg 4. 8 is a capacitor for phase advance, 9 is its discharge resistance, 10A, 10B is a 40W discharge lamp, 11
1 is a coil for preheating the filament (omitted in Figure 2); 12 is a capacitor for noise prevention;
3 is a capacitor for sequential lighting.

Both discharge lamps 10A and 10B are connected in series, and the secondary voltage of the ballast 2 is connected to the capacitor 8 and the discharge resistor 9.
is applied through a parallel circuit with capacitor 1
2 are connected to both ends of a series circuit of both discharge lamps, and a capacitor 13 is connected in parallel to one of the discharge lamps.

The above configuration is not particularly different from a normal lighting device of this type, and the no-load secondary voltage of the ballast 2
300V is applied to the discharge lamp 10A via the capacitor 13, thereby causing the discharge lamp 10A to start discharging. With the start of this discharge, the discharge lamp 10
Since the impedance of A decreases, the secondary voltage of the ballast 2 then passes through the discharge lamp 10A to the discharge lamp 10.
applied to B. By this application, the discharge lamp 10B
starts discharging. As a result of the start of discharge of both discharge lamps, both discharge lamps are instantaneously lit at the same time. The above operation is already well known as rabbit start type operation.

According to this idea, an intermediate tap 15 is provided on the primary coil 5 of the ballast 2, and a secondary coil 6 is connected to this to form a single-turn transformer type. The commercial AC power supply 1 is connected to both ends of the primary coil 5, and the voltage between the end a of the primary coil 5 and the intermediate tap 15 (this is referred to as VE ₁ ) and the voltage between the intermediate tap 15 and the primary coil 5 are connected to each other. The voltage that is the sum of the voltage between the secondary coil 6 and the end of the secondary coil 6 (this is referred to as VE ₂ ) becomes the secondary voltage of the ballast 2 .

In the above configuration, the magnitude of voltage at each part when both discharge lamps are lit will be examined. now discharge lamp 1
The voltage across the series circuit of 0A and 10B, that is, the lamp voltage of two discharge lamps, 2VL185V, is constant.
The number of turns of each coil of the ballast shall be determined so that the no-load secondary voltage V ₂ is always 300V. Furthermore, the voltage of commercial AC power supply 1 is set to 100V. Here, when the intermediate tap 15 is pulled out from the 80V point of the primary coil 5 (therefore, VE ₁ = 80V), the end
The voltage between ab and V _ab is VE ₁ + VE ₂ + where V _ch is the voltage drop due to the inductance of stabilizer 2.
V _ch and the voltage between the intermediate tap 15 and the end b are VE ₂ +V _ch (ignoring the voltage drop due to the inductance between the end a and the intermediate tap 15). A vector diagram drawn from the actual measurement results is shown in Figure 3A. However, the terminal voltage of capacitor 8 V _c . The voltage across the series circuit of the capacitor 8 and the ballast 2, that is, the voltage V _B , which is the sum of the terminal voltage of the capacitor 8 and the voltage V _ch , was actually measured. The voltages at this time were as follows.

VE ₁ = 80V, VE ₂ +V _ch = 230V VE ₁ +VE ₂ +V _ch = 280V V _c = 200V From the vector diagram Figure 3A drawn based on these measurements, VE ₂ = 150V, V _ch = 190V Therefore, VE ₁ + VE ₂ = 185V was determined.

On the other hand, in the conventional configuration in which the secondary coil 6 is connected in series with all of the primary coils 5 (if the intermediate tap 15 is not provided as in this invention, VE ₁ = 100V). If the no-load secondary voltage and lamp voltage are the same, a vector diagram drawn from each actual measurement value at that time will be as shown in Figure 3C. In the figure, VE ₂ +V _ch = 250V VE ₁ +VE ₂ +V _ch = 300V V _c = 215V Therefore, VE ₂ = 95V, V _ch = 190V Therefore, VE ₁ + VE ₂ = 195V When compared with Figure 3 A , the voltage V _c and VE ₁ +VE ₂ are smaller in the case of FIG. 3A.
From this result, in the configuration in which the intermediate tap 15 is provided and the secondary coil is connected to it, the capacitor 8 has a lower withstand voltage than the configuration in which both the primary and secondary coils are connected in series without providing an intermediate tap. In addition, the ballast 2 can be designed with a small volt-ampere.

When the intermediate tap 15 is set to the 60V position, VE ₁ = 60V, VE ₂ +V _ch = 230V VE ₁ +VE ₂ +V _ch = 290V V _c = 190V, and VE ₂ = 127V, V _ch = 200V. Therefore, VE ₁ + VE ₂ = 187V, and if we draw a vector diagram from this, it will look like Figure 3 B. From this result, as can be understood from this vector diagram, the lighting circuit becomes inductive, the voltage V _ch also increases, and the ballast 2 becomes larger, which is inconvenient. Therefore, the position of the intermediate tap 15 is limited to 70V. Alternatively, from FIG. 3, it can be said that the limit is the point where voltage V _ch becomes approximately equal to voltage V _c .

The above explanation assumes that the voltage of commercial AC power supply 1 is
Although we have discussed the case of 100V, similar results can be obtained even if this is a different voltage, for example 200V.

(Effects of the invention) As detailed above, according to this invention, even a capacitor with a low withstand voltage can be used as a phase advance capacitor, and furthermore, it is possible to use a low volt-ampere stabilizer.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing an embodiment of this invention, Figure 2 is a circuit diagram showing an embodiment of this invention.
The figure is a sectional view of the ballast, and FIG. 3 is a vector diagram for explaining the operation. 1... Commercial AC power supply, 2... Ballast, 3... Iron core, 5... Primary coil, 6... Secondary coil, 7...
...bridge gap, 8...phase advancement capacitor,
10A, 10B...Discharge lamp, 15...Intermediate tap.

Claims (1)

[Scope of utility model registration request] The primary and secondary
Rabbit start type discharge lamp lighting consisting of a ballast provided with a second coil, and a circuit in which two 40W discharge lamps are connected in series, to which the output voltage of the ballast is applied via a phase advance capacitor. In the device, an intermediate tap is provided in the primary coil of the ballast to which the lighting power source is connected, at a position where the primary coil generates a voltage of 70 V or more and less than 100 V, and the secondary tap is connected to the ballast through the intermediate tap. A discharge lamp lighting device comprising a secondary coil connected in series to the primary coil.