JPS5919432B2 - Protective device in discharge lamp lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a protection system for a discharge lamp lighting device, and more particularly to a protection system for preventing an intermittent high-voltage circuit from running out of control when an abnormality occurs in a discharge lamp in an annual cycle start lighting system.

The present inventor has previously proposed an annual cycle lighting system that is extremely effective in terms of resource and energy saving, which makes it possible to improve efficiency, make the current limiting choke smaller and lighter, and save energy.

FIG. 1 is an electrical circuit diagram showing a line of discharge lamp lighting devices using an annual cycle start lighting method, which is the background of the present invention.

In the configuration, a discharge lamp 3 is connected to an AC power source 1 via a primary winding 21 of a current limiting choke 2. A high voltage circuit 4 shown as an intermittent high voltage means is connected to the non-power side of the filaments 31 and 32 of the discharge lamp 3 via the secondary winding 22 of the current limiting choke 2. The intermittent oscillation capacitor 6 is connected in series to a boost circuit 5 which is formed by connecting a series circuit of a thyristor 52 and a boost inductor 53 in parallel to a No. 4 oscillation capacitor 51 of the high voltage circuit. In operation, when the power supply 1 is turned on, the power supply voltage e is applied to the discharge lamp 3 via the primary winding 21 of the current limiting choke 2,
At the same time, the primary winding 21 of the current limiting choke 2, the filaments 31 and 32 of the discharge lamp 3, and the secondary winding 2 of the current limiting choke 2
2 to the high voltage circuit 4.

This voltage e causes the thyristor 52 constituting the booster circuit 5 to go into overdrive. Therefore, this booster circuit 5 starts boosting oscillation. This oscillation operation would continue without the intermittent oscillation capacitor 6, but if this capacitor 6 is present, the voltage at its terminals charged by the input current of the booster circuit 5 cancels out the power supply voltage. It oscillates intermittently every time the voltage e rises in each half cycle. The high frequency component of this booster circuit 5 is voltage-divided by the primary winding 21 and secondary winding 22 of the current limiting choke 2, and the terminal voltage of the primary winding 21 is superimposed on the power supply voltage e, and the discharge lamp 3 is applied. Filament 31 of discharge lamp 3
and 32 are preheated by the input current of the high voltage circuit 4.

That is, during the oscillation period of the booster circuit 5, the power source 1, the primary winding 21 of the current limiting circuit 2, the filament 31, the current limiting circuit 3, the secondary winding 22 of the current limiting circuit 2, the high voltage circuit 4, the filament 32, An input current flows through the path of the power supply 1. Since the secondary winding 22 of the current limiting choke 2 has additive polarity with respect to the primary winding 21VC, by increasing the number of turns, the input current can be reduced to 2
This can be increased compared to the case where there is no secondary winding 22. Thus, when the filaments 31 and 32 are sufficiently heated,
Triggered by the output voltage of the high voltage circuit 4, the discharge lamp 3 is started and lit.

When the discharge lamp 3 is turned on, a tube current IT flows through the discharge lamp 3. As this tube current IT flows through the primary winding 21 of the current limiting choke 2, its impedance changes,
The period during which the input current 1R appears is shorter than during preheating. Therefore, while the discharge lamp 3 is lit, the preheating current of the filaments 31 and 32 based on the input current IR decreases. When the discharge lamp 3 is lit in this manner, the oscillation period of the high voltage circuit 4 is shortened and the load becomes light. Thereafter, the discharge lamp 3 is re-ignited by the output voltage VR of the high voltage circuit 4 every half cycle of the power supply 1, and is maintained lit by the power supply voltage EK. Figure 2 is the first
The waveforms of various parts during lighting, obtained by simulation of the equivalent circuit of the device shown in the figure, are shown.

However, high frequency components are ignored in these waveforms. In this figure, the tube voltage VT becomes a rectangular wave having a rest period due to an intermittent oscillation period, as shown in FIG. 2 BflC. Therefore, the tube voltage VTf)44 effective value VT shows a slightly lower value compared to the conventional lighting system. Also, Figure 2 E
As shown in FIG. 2B, the intermittent input current 1R flowing into the high voltage circuit 4 flows through the primary winding 21 of the current limiting choke 2, so that the waveform of the tube voltage VT changes to the input current as shown in FIG. 2B. It is slightly increased due to the influence of 1R.

The appearance phase of the input current 1R shown in Figure 2D is constant regardless of fluctuations in the power supply voltage e, and therefore the rising phase of the tube current 1T shown in Figure 2C is constant regardless of fluctuations in the power supply voltage e. keep it. Also, if the magnitude of the input current 1R and the power supply voltage e
If the tube current 1T increases due to an increase in , the rear end of the tube current 1T waveform becomes the input current I of the next half cycle. VCVI. i.e. has a negative coefficient of variation. These are the reasons why the fluctuation rate of the tube current 1T in the half-cycle start lighting method is maintained well despite the decrease in stable impedance. Said tube voltage VTl tube current 1T, human power current 1R to high voltage circuit 4
When the instantaneous reactive power (VOHi) of the current limiting choke 2 and the stored energy S are calculated from the waveforms of the single-shot output voltage VR and the power supply voltage e, the waveforms shown in F and G in the figure are obtained.

In the same figure F, S1 is the energy stored by the input current 1R during the oscillation period (T, ~T2), and S2 is the energy stored during the period (T2 ~ T3) where the voltage e is higher than the tube voltage VT. , S3 is the energy released during the period (T3 to T4) where the tube voltage VT is higher than the voltage e, and S1
The relationship +S2=S3 holds true. Here, the current limiting circuit 2VC. One of the reasons for providing the secondary winding 22: Regardless of the decrease in the number of turns of the primary winding 21 of the current limiting choke 2, the value of the instantaneous reactive power S1 is kept high, and the effect of improving the fluctuation rate due to the input current 1R is maintained. I understand that there is something to be done. NextFigure 2G
shows the accumulated energy waveform of the current-limiting choke 2 obtained by integrating the instantaneous reactive power shown in FIG.

As a result, if you calculate the amount of stored energy, the necessary current limiting, and inductance, it will be about 11.1 compared to the conventional single yoke type glow lighting system.As a result, the ballast (current limiting yoke type) (plus the high voltage circuit 4) can be reduced to 1/4 the weight.

Furthermore, compared to the conventional rabbit lighting system, the weight of the ballast can be reduced to 1/11. Furthermore, according to the half-cycle start lighting method, the phase difference between the power supply voltage e and the tube current 1T is smaller than in the conventional lighting method, so a power factor correction capacitor is not necessary, or the capacitance can be made extremely small. .

Note that the high-voltage circuit 4 may be replaced with a high-voltage circuit using a gated thyristor such as Triafuku, or even an inverter, as long as it generates high-frequency high voltage intermittently.

As described above, the half-cycle start lighting method, which is the background of the present invention, is very advantageous in terms of the size and weight of the current limiting choke, but it encounters the following problems.

In other words, for example, if the emitter of the filament of a discharge lamp is consumed to almost zero (this is called an abnormality)
, if the filament does not break, the discharge lamp will continue to glow discharge, but will not transition to arc discharge. Therefore, this discharge lamp produces a faint discharge. At this time, the current flowing through the primary winding 21 of the current limiting circuit 2 is not zero, but is very small, so the charging period of the intermittent oscillation capacitor 6 increases, and the boost circuit 5, that is, the high voltage circuit 4Q The oscillation period increases and exhibits a state similar to that at startup, with almost the entire range VC$? of each half cycle. oscillation may continue. In this case, the input current to the high voltage circuit 4 is naturally large, and the voltage across each component of the high voltage circuit, particularly the capacitor 6, is large. Therefore, the intermittent oscillation capacitor 6 needs to be an AC capacitor or a large-capacity DC capacitor. For this purpose, this high voltage circuit 4
becomes large and expensive. Therefore, the main object of the present invention is to provide a lighting device that starts every half cycle, which can be made small and inexpensive, and can completely protect the capacitors and booster circuits without increasing the capacitance of the intermittent oscillation capacitors and other parts used in the booster circuit. An object of the present invention is to provide a protection method for a discharge lamp lighting device according to the present invention.

To summarize, the present invention provides a discharge lamp lighting device that uses a lighting method that starts every half cycle, connects the discharge lamp to an AC power source through the primary winding of a current-limiting choke, and (c) The secondary winding is included as part of the intermittent high voltage circuit and connected to the AC power supply, and when an abnormality occurs, the current between the discharge lamp connection terminals is induced into the closed circuit of the primary winding, and the intermittent high voltage circuit is This is a protection device designed to limit the current generated during abnormalities.

The above-mentioned objects and other objects and features of the present invention will become more apparent from the following detailed description with reference to the drawings.

FIG. 3 is an electrical circuit diagram showing one embodiment of the present invention.

In construction, this embodiment is similar to that shown in FIG. 1, with the following exceptions. That is, the high voltage circuit 4 includes two boost circuits 5 and 5'. and,
The booster circuit 5 includes a filament 31, and the filament 32 is included in the booster circuit 5'. Further, an intermittent oscillation capacitor 6 and a current limiting choke 2 are connected between the booster circuits 5 and 5'.
A series circuit of secondary windings 22' is inserted.

Furthermore, a resistor 54 for sequential activation is connected in parallel to the thyristor 52' of one booster circuit 5'. Therefore, when the low frequency AC power supply 1 is turned on, the booster circuit 5 is activated first, and then the booster circuit 5' is activated. Therefore, the filament of discharge lamp 3 costs 31 dollars? and 32 are sufficiently preheated by the high frequency current flowing through the booster circuits 5 and 5'. The high-frequency superimposed voltage of the booster circuits 5 and 5' is applied to both ends of the discharge lamp 3 as a low-frequency power supply voltage e from the low-frequency AC power supply 1.
is applied in a superimposed manner, thereby starting and lighting the discharge lamp 3. In this embodiment, impedance means 7, which is a feature of the present invention, is further connected to the power source side of the discharge lamp 3.

The impedance means 7 consists of a series circuit of a capacitor 71 of relatively small capacity and a resistor 72 of relatively high resistance, but other circuits may be used as long as they can obtain a current similar to a weak current. Preferably, the current flowing through the impedance means 7 is set to about several μA to several + MA, which corresponds to the glow discharge of the discharge lamp 3. Of course, this current value must be selected within a range that does not affect the normal lighting of the discharge lamp 3. Furthermore, the secondary winding 22'&ζ of this embodiment is different from the secondary winding 22 shown in FIG.

That is, this secondary winding 22 is different from that shown in FIG.
The next winding 22' may have a very small number of windings, and its polarity is not limited to magnetizing or demagnetizing. For example, if the number of turns of the primary winding 21 is n1 and the number of turns of the secondary winding 22' is N2, the ratio is selected to be n1:N2=4 to 10:1. Furthermore, 8 is a bypass capacitor for preventing high frequency leakage to the power supply line connected in parallel with 1 VC of low frequency AC power supply. In operation, consider a case where the emitter of the filament of the discharge lamp 3 disappears and the discharge lamp 3 is no longer lit normally.

At this time, a very small amount of the high frequency component of the high voltage circuit 4 flows in the closed loop including the impedance means 7 and the secondary winding 22/ of the current limiting choke. Therefore, this high frequency component comes from the secondary winding 22'! It is induced between the terminals of the next winding 21 according to the turns ratio n1/N2. here,
Regardless of the presence or absence of the bypass capacitor 8, the AC power supply 1 is considered to be almost in a short-circuited state in terms of high frequency. Therefore, a minute current (
This may be a minute current flowing through the discharge lamp 3)Rc
The resulting current in the primary winding 21 is shunted on the primary side. Therefore, a large loss occurs in the core of the closed-loop current-sucking choke including the primary winding 21, causing the impedance of the primary winding 21 to become low. Therefore, the oscillation period of the high voltage circuit 4 is shortened as in the case of normal lighting. In other words, the large current flowing through the impedance means 7 has the same effect as the current accompanying the VC during normal lighting (arc discharge) of the discharge lamp 3, thereby shortening the oscillation period of the high voltage circuit 4. . Therefore, even if the discharge level is 3
Even if there is no discharge at all, the oscillation period of the high voltage circuit 4 is comparable to that during normal lighting, and overload of the high voltage circuit 4 can be prevented. FIG. 4 is an electrical circuit diagram showing another embodiment of the invention.

In construction, this embodiment is similar to that of FIG. 3 with the following exceptions. That is, this practical example shows a parallel lighting device for two discharge lamps 3 and 3'. Therefore, the current limiter 2 for one discharge lamp 3VC (this is 2
(having a secondary winding 22') and a current limiting choke 25 (this is a single choke) for the other discharge lamp 3I are magnetically coupled through an integral magnetic path. When the discharge lamp 3 is ignited by the operation of the high-voltage circuit 4, the current that accompanies the discharge lamp 3 is transmitted from the current-limiting choke 2 to the current limiting choke 2'. Therefore, the voltage of the low-frequency AC power supply 1 and the transmitted low-frequency and high-frequency energy are applied to both ends of the discharge lamp 3' in a superimposed manner. Therefore, the discharge lamp 3' is started mainly by the high frequency component and is re-ignited only by the low frequency component during lighting. According to this embodiment, it is only necessary to provide a single high-voltage circuit 4 for a plurality of discharge lamps, and a lighting device for a plurality of discharge lamps can be obtained at a lower cost. Impedance means 7 consisting of a capacitor 71 and resistors 72 and 73 is connected in parallel to the discharge lamp 3 for the purpose of circuit protection in abnormal situations. When an abnormality occurs in the discharge lamp 3, a small current flows through the impedance means 7rc due to the relationship between the charging time constant of the capacitor 71 and the resistor 12rc, and the discharging time constant of the capacitor 71 and the resistor 73. The primary winding 21 of the high voltage circuit 4 is shunted, and the oscillation period of the high voltage circuit 4 is shortened.

Therefore, it is possible to obtain an intermittent input current and make the voltage across the intermittent oscillation capacitor 6 a small value with a rectangular waveform similar to that during normal lighting, and this capacitor 6 can be made smaller and smaller in capacity. At the same time, stress on other parts is also reduced. Further, after the power supply 1 is turned off, the charge in the capacitor 71 is discharged through the resistor 73. In the embodiment shown in FIG. 4, the filaments 31' and 32' of the discharge lamp 3' are formed by filament windings 91' and 32', which are integrally magnetically coupled to the current-limiting yokes 2 and 2'. and 92rc.

FIG. 5 is an electrical circuit diagram showing another embodiment of the present invention. Due to its structure, this actual example has the following exceptions:
It is similar to that in FIG. That is, the secondary winding 22' in this embodiment is also the same as the secondary winding 22' shown in FIGS. 3 and 4 above.
Like the secondary winding 22', it has a different effect than the secondary winding 22 shown in FIG. Furthermore, in this embodiment, the filaments 31 and 32 of the discharge lamp 3 are connected to the heater transformer 1.
0 filament winding 101$? and 102
It was preheated by Therefore, even if the discharge lamp 3 is removed from the socket, the high voltage circuit 4 continues to operate, and therefore there is an urgent need for measures against abnormalities. Here, similarly to the circuit of FIG. 3 or 4, impedance means 7 is connected in parallel to discharge lamp 3. The operation of this embodiment differs from that in FIGS. 3 and 4 in that the shortening of the oscillation period is entirely dependent on the impedance circuit 7.
By connecting the impedance means T in this manner, even when the discharge lamp 3 is removed, a minute current is caused to flow through the impedance means 7, thereby shortening the oscillation period of the high voltage circuit 4. As described above, according to the present invention, even in an abnormal situation such as when the emitter of a discharge lamp is exhausted, protection can be achieved without increasing the capacity of each component of the high voltage circuit.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram showing a discharge lamp lighting device using a lighting method that starts every half cycle, which is the background of the present invention. FIG. 2 is a waveform diagram of each part for explaining the operation of the electric diagram. 3 to 5 are electrical circuit diagrams showing different embodiments of the present invention. In the figure, 1 is a low frequency AC power supply, 2 and 2' are current limiting chokes, 21 is a primary winding,
22 and 22' are secondary windings, 3 and 3' are discharge lamps, 4 is a high voltage circuit, and 7 is an impedance means.

Claims (1)

[Claims] 1. A low-frequency AC power supply, a current-limiting device including a primary winding and a secondary winding, and the low-frequency AC power supply voltage is applied through the primary winding of the current-limiting device. a discharge lamp; and an intermittent high voltage means to which the low frequency power supply voltage is applied through the primary winding and the secondary winding of the current limiting device and which intermittently generates a high frequency high voltage every half cycle thereof. A protection device for a discharge lamp lighting device comprising: a high frequency current path from the intermittent high voltage means including the secondary winding and passing between the electrodes of the discharge lamp when the discharge lamp is abnormal; The oscillation period of the intermittent high voltage means is reduced by converting the high frequency current flowing through the high frequency current path from the secondary winding of the current limiting device to the primary winding, and shunting the primary winding side at high frequency. A protection device for a discharge lamp lighting device designed to shorten the length. 2. The protection device for a discharge lamp lighting device according to claim 1, wherein the high-frequency current path includes the discharge lamp itself in a glow discharge state. 3. A protection device for a discharge lamp lighting device according to claim 1, wherein the high frequency current path includes an impedance means connected in parallel to the discharge lamp. 4. A protection device for a discharge lamp lighting device according to claim 1, wherein the high frequency current path includes a discharge lamp in a glow discharge state and an impedance means connected in parallel thereto.