JPS6118319B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a discharge lamp lighting device, and more particularly to a discharge lamp lighting device that maintains the discharge lamp lit by compensating for the disappearance or reduction of ions during the rest period of the overflow current of the discharge lamp. It is.

With the recent trend toward solid-state electrical equipment, semiconductor devices are also being used in the field of discharge lamp lighting devices. The present inventor previously proposed a discharge lamp lighting device having excellent characteristics using a thyristor having voltage-sensitive characteristics such as a bidirectional two-terminal thyristor (Japanese Patent Publication No. 49-3184). This discharge lamp lighting device basically consists of a first oscillating circuit consisting of a series circuit of a power supply, a linear inductor, and a capacitor, and a series circuit of a bouncing boost inductor and a bidirectional two-terminal thyristor connected in parallel to the capacitor. The present invention utilizes an oscillator (Japanese Patent Publication No. 11485/1985) including a second oscillation circuit made up of the above-mentioned bouncing boost inductor and its distributed capacitance. In such an oscillation circuit, the high voltage oscillation voltage generated across the capacitor is utilized. A discharge lamp is connected to both ends of the capacitor, and the filament is connected to the first or second terminal for the purpose of rapidly heating the filament.
It is often connected in series to the common circuit of the oscillating circuit.

FIG. 1 shows a circuit diagram of an oscillator used in the lighting device of the present invention. Prior to detailed description of the embodiments of the present invention, the structure and operation of this oscillator will first be described within the scope necessary for understanding the present invention.
The details of the configuration and operation of this oscillator are described in the aforementioned Japanese Patent Publication No. 11485/1985.

The oscillator in Figure 1 consists of a linear inductor L1 such as a chiyoke coil and a leakage transformer connected in series to a power supply E, a capacitor C, and a power switch.
A first oscillating circuit R1 consisting of SW and a boosting inductor L2 connected in parallel to the capacitor C.
(hereinafter simply referred to as inductor L2) and a second oscillating circuit R2 in which a series circuit of a thyristor S that operates in response to voltage such as a bidirectional two-terminal thyristor is connected, and the inductor L2 and its distributed capacitance C ' A third vibration circuit R3 consisting of
including. The inductor L2 has a characteristic that it is magnetically saturated and the inductance value decreases when the overflow current increases, and is also dielectric, such as Mn-
This can be achieved by using magnetic materials such as Zn-based ferrite. Further, the voltage versus current characteristics of a typical bidirectional two-terminal thyristor used as the thyristor S is shown in FIG. The characteristics of FIG. 2 and thyristors having such characteristics are well known to those skilled in the art and will not be described in detail. The vibration period of the second vibration circuit R2 is selected to be smaller than the vibration period of the first vibration circuit R1, depending on the inductance ls of the inductor L2 at saturation. The distributed capacitance C' of inductor L2 is shown equivalently connected in parallel with inductor L2. Furthermore, the equivalent loss resistance r' of inductor L2 is shown connected in parallel with inductor L2.

FIG. 3A shows the time course of the voltage V _C generated by the oscillating circuit R2 across the capacitor C and the input current I1 when direct current is used as the power source E. FIG.

FIG. 4 shows voltage and current waveforms in which the time axis of FIG. 3A is expanded when the oscillation is stable.

In the configuration shown in Figure 1, when the switch SW is turned on, the capacitor C is charged and the terminal voltage V _C
Increase. The terminal voltage V _C is applied to the thyristor S via the inductor L2, but since the inductor L2 has almost no impedance against such low-frequency voltage changes, the applied voltage (at time A in Figure 3) When the breakdown voltage V _BO of the thyristor S is exceeded (at t1), the thyristor S is turned on and the charge on the capacitor C is discharged through the series circuit of the inductor L2 and the thyristor S. As shown in FIG. 4, this discharge current I _C advances by approximately π/2 with respect to the waveform change of the voltage V _C which decreases due to discharge, increases sinusoidally, and then decreases. The current I _C flows through the second oscillating circuit R2 due to the saturation of the inductor L2.
When the Q of is high, it reaches an extremely large value. The inductance ls of the inductor L2 when it is saturated is extremely small compared to the inductance lu when it is not saturated. As the capacitor C discharges, the current I _C decreases and therefore the current I2 flowing through the thyristor S decreases. That is, I2 is E-L1-L2-S- from the discharge current I _C of capacitor C and power supply E.
It is given by the sum of the current I1 when the thyristor S is turned on, which is supplied through the path of E, but in the initial stage, the rise is very slow due to the large inductance of the linear inductor L1, and the current value is very small. This is small and can be ignored. Therefore, when I2 becomes equal to or less than the holding current I _H of thyristor S (at time t2), thyristor S is turned off. During the conduction period of the thyristor S, the charge on the capacitor C changes, and the polarity of the voltage V _C is reversed and becomes a voltage slightly higher than -V _BO due to losses due to resistor r' and the like. Therefore, the thyristor S is not immediately turned on in the opposite direction. Note that when the thyristor S is conductive, the capacitor C and the inductor L
Since it is connected in parallel with the distributed capacitance C′ of 2,
At the same time, the distributed capacitance C' is charged to a voltage of about -V _BO with the same polarity and the same voltage as the capacitor C.

When the thyristor S enters the blocking state in this manner, the inductor L2 returns to the non-saturated state.

Once the thyristor S is in the blocking state, the charging process of the primary circuit begins again. This time, when the thyristor S changes to the blocking state, the primary current that was about to cause the thyristor S to enter the blocking state remains almost unchanged due to the electromagnetic energy previously accumulated in the inductor L1, so unlike the first charging, The initial value of the primary current is not zero. In addition, since the original capacitor charging current similar to the initial charging flows in a superimposed manner, the capacitor charging current is ultimately given as the sum current I1 of these two currents. In this way, due to the constant current function of the inductor L1, the capacitor C is charged more rapidly, and the voltage V _C rises linearly, crossing the O line from -V _BO to +V _BO and further growing. . During this time, even if V _C becomes more than V _BO , thyristor S does not conduct. This is a major feature of this boost oscillator. The reason for this is that electrostatic energy was accumulated in the distributed capacitance C' of the inductor L2 due to the discharge that occurred earlier. By gradually discharging the electrostatic energy stored in the capacitor C, a terminal voltage V _C of the capacitor C is generated across the inductor L2 as shown in FIG.
In order to generate a so-called rebound voltage V _L2 with the opposite polarity, and to cause this rebound voltage V _L2 to damped oscillate between the non-saturated inductance lu of the inductor L2 and the distributed capacitance C' as shown by the dotted line in the figure. , the terminal voltage of the inductor L2 remains for a relatively long time (more than the time between time t2 and time t3). If the configuration of inductor L2 is chosen appropriately, the rate of change of this voltage, that is _, the rebound voltage _V It can be made very similar to the rate of change. In such a case, the terminal voltage of the thyristor S, which is determined by the difference between the voltage V _C and the voltage V _L2 , is maintained at a low voltage for a considerable period of time despite the rise in the terminal voltage V _C of the capacitor C. This prevents the thyristor S from conducting, and as a result, the capacitor C continues to be charged during this time, so that V _C continues to increase linearly. However, since the rebound voltage V _L2 undergoes damped oscillation as described above, the voltage difference between the terminal voltage V _C of the capacitor C and the rebound voltage V _L2 gradually increases, and when the voltage difference finally reaches V _BO , the voltage difference between the terminal voltage V C of the capacitor C and the rebound voltage V L2 increases is turned on again.

Here, the direction of the discharge current I _C ' of the distributed capacitance C' is the discharge current I _C of the capacitor C with respect to the inductor L2.
In the opposite direction, the inductor L2 quickly returns to the saturated state.

Therefore, if charging and discharging are repeated several times, the capacitor charging current will increase each time the capacitor is charged, and the capacitor charging cycle will become shorter.

On the other hand, each time a discharge occurs, E-L1-L2 as mentioned above.
- Due to the increase in the primary current supplied through the S-E path and the rise in the terminal voltage V _C of capacitor C before thyristor S conducts, capacitor C discharges when thyristor S conducts. The current flowing through the inductor L2 increases accordingly. Therefore, the electrostatic energy due to the distributed capacitance C' increases, and the oscillating circuit R generated across the inductor L2 when the thyristor S enters the blocking state.
The rebound voltage V _L2 due to 3 also increases.

In this way, the voltage V _C is amplified in the charging circuit, and the voltage V _C is inverted and the rebound voltage V _L2 is amplified in the discharging circuit, and the voltage V _C (=V _BO + V _L2 ) gradually increases until it reaches the extreme voltage V _C. As a result, voltage V _C is increased to the point where voltage V _L2 can follow it. This stable state is a stable state of the primary current I1, and the value of the primary current I1 at that time is compared to the stable value of the input current I1' in the circuit in which the capacitor C is removed and the thyristor S is shorted in FIG. However, it is slightly lower. The oscillation period is determined for this stable voltage V _C .

After this operation is repeated, the circuit operates in oscillation and provides an alternating current output. This state is shown in FIG. 3A. Ultimately, the envelope of the oscillation output voltage V _C saturates to a value determined by the circuit constants.

In this way, an alternating voltage that is higher than the power supply voltage and has a relatively high frequency is obtained across the capacitor C. According to one example of circuit design, the oscillation frequency is several tens of kilohertz and the oscillation voltage is approximately 10 times the power supply voltage.

It is understood that alternating current can also be used as the power source E since the oscillation frequency is high. When the power source E is an AC voltage e, the oscillation output voltage V _C as shown in Figure 3B
It can be seen that the envelope corresponds to a sinusoidal waveform that is in phase with the AC input current i1 and symmetrical with respect to the time axis.

Furthermore, it can be seen that the above-mentioned effect is not lost even when a phase advance capacitor is connected in series with the inductor L1 in FIG. 1 to constitute a so-called phase advance current limiting device.

The discharge lamp lighting device which is the premise of this invention is the first
This utilizes the high voltage oscillation output generated across capacitor C of the oscillation circuit shown in the figure. When lighting a single discharge lamp, for example, as shown in Figure 5, the discharge lamp FL
is connected across the capacitor C, and its filaments f1 and f2 are connected in series within the second oscillating circuit R2. The configuration of the oscillation circuit is the same as that shown in FIG. 1, and the same parts are denoted by the same reference numerals. However, the third vibration circuit R3 is omitted to simplify the drawing (Japanese Patent Publication No. 49-3184).

FIG. 2 also shows load lines for explaining the circuit operation of FIG. 5. Therefore, this second
The operation of the apparatus shown in FIG. 5 will be explained below with reference to the drawings.

The maximum value of the power supply voltage V _E , the peak value of the tube voltage of the discharge lamp (hereinafter referred to as spike voltage) V _FL , the breakdown voltage V _BO of the thyristor S, and the effective breakdown voltage V _BO ′ during lighting of the discharge lamp FL are as follows. Selected based on the relationship of the expression.

V _E > V _BO , V _BO ′ > V _FL In other words, the breakdown voltage of the thyristor S at the time of starting the discharge lamp FL is with respect to the commercial frequency f, so the impedance of the inductor L2 (ωlu = 2πflu) is small. Since it can be ignored, it is given by V _BO in Figure 2.

Due to the relationship V _E >V _BO , oscillation starts when the power switch SW is turned on, and a high voltage V _C is generated across the capacitor C. Further, a large high-frequency oscillation current flowing through the oscillating circuit R2 preheats the filaments f1 and f2 of the discharge lamp FL. Thus, when the filaments f1 and f2 are sufficiently heated, the discharge lamp FL is lit by the high voltage.

During the lighting of the discharge lamp FL, the peak value of the tube voltage becomes a problem, and when the discharge lamp FL is lit again, the peak value of the tube voltage occurs at the rising part of the tube voltage waveform every half cycle due to the inductance skimming action of the inductor L1. The spike voltage must not exceed the effective breakdown voltage V _BO ' of the thyristor S. This spike voltage becomes larger as the temperature becomes lower, and corresponds to a high frequency of about 1.5 KHz. For such a high frequency fh, the impedance 2πfhlu' of the inductor L2 is much larger than that for low frequencies such as the power supply frequency, so that the impedance of the thyristor S seen from both ends of the series circuit of the inductor L2 and the thyristor S is As shown in Fig. 2, the effective breakdown voltage V _BO ' is calculated when the impedance 2πfhlu' line of the equivalent inductance lu' during non-oscillation with respect to the spike voltage frequency fh is located on the coordinates of the breakdown current I _BO given at the point where it intersects the voltage axis,
It should be noted that V _BO ′>V _BO and that erroneous conduction of the thyristor S due to spike voltage can be prevented. Further, the equivalent inductance lu' is proportional to the effective magnetic permeability μe of the core. Therefore, the core of inductor L2 used in this invention has a large effective magnetic permeability μe at low temperatures.
Mn/Zn ferrite is suitable. Inductor L
If the impedance 2πfhlu' with respect to the equivalent inductance lu' of 2 is sufficiently large, Fig. 2B
It is also possible to use a triggering thyristor with typical characteristics. Thus, from the relationship V _BO ′>V _FL , when the discharge lamp FL is lit, the thyristor S is turned off and the oscillation circuit R2 stops its oscillation operation.
The discharge lamp FL continues to discharge. At this time, the inductor L1 functions as a conventional chiyoke coil, and the capacitor C functions as a noise prevention capacitor.

In the lighting circuit shown in Fig. 5, a linear inductor L1 containing only an inductance component is used as a current limiting device to achieve slow phase lighting, but it is possible to connect a phase advance capacitor to this linear inductance L1 to achieve phase advance lighting. You can also do it. As a result, the ratio of tube voltage fluctuation to power supply voltage fluctuation becomes relatively small, and the secondary open circuit voltage (filament f1, f2
This has the advantage that the no-load voltage or power supply voltage between tubes only needs to be set slightly higher than the tube voltage.

In the lighting method of the discharge lamp lighting device as shown in Fig. 5, after the discharge lamp is lit, the vibration circuit R2
will cease operation. At that time, the rated voltage of the discharge lamp FL is generally about half of the voltage of the power source E. For example, in the example shown in Figure 5, if the power supply voltage is 200V and the discharge lamp FL is 40W, the tube voltage of the discharge lamp FL is V _FL
is about 100V, and a voltage of about 150V is applied to the inductor L1 due to the delayed current phase.
On the other hand, in the rapid lighting method that does not use the oscillating circuit R2, the power supply voltage (for example, 200V) is boosted (for example, 230V) by a transformer and applied to the discharge lamp.
Since a sufficient starting voltage cannot be obtained with this, for example, a conductive coating is provided inside the tube of the discharge lamp to lower the starting voltage of the discharge lamp to achieve lighting of the discharge lamp.
Since the characteristics of the discharge lamp when lit are the same as those shown in Fig. 5, the tube voltage when lit is about 100V. Therefore, the current limiting device requires the secondary voltage of the transformer.
A difference of 130V between 230V and the tube voltage of 100V is applied. However, since the power factor is low, approximately 200V is equivalently applied to the current limiting device. Originally, the size of a current limiter is determined by the terminal voltage (V) and the current flowing there (A).
It is determined by the product VA (volt-ampere). Since the tube current (A) is fixed, the terminal voltage (V)
By reducing , the current limiting device can be made smaller. However, in both the conventional glow lighting system and the rapid lighting system, a difference between the tube voltage and the starting voltage is unavoidable, so there is a limit to the miniaturization of the current limiting device. As mentioned above, one way to improve this is to include a phase advance capacitor in the current limiting device, but there is still a limit to miniaturization, and this cannot be a revolutionary improvement. . In addition, a power factor correction impedance may be inserted in parallel with the power supply to improve the power factor. For example, in a 60Hz area, if you are using 200V, 40W, and one light with a delayed phase, it is recommended to insert a 3.5μF capacitor. However, in any of the cases described above, there is a limit to the miniaturization of the current limiting device, and it has been difficult to achieve revolutionary miniaturization.

Therefore, a main object of the present invention is to overcome the above-mentioned problems and provide a discharge lamp lighting device that can be made smaller and lighter.

Other objects and features of the invention will become more apparent from the following detailed description with reference to the drawings.

Briefly, the present invention provides a method for lighting a discharge lamp using low-frequency alternating current, in which the low-frequency overcurrent of the discharge lamp is superimposed so as to include a rest period,
During the first part of each half cycle of said low frequency alternating current, at least a high frequency current is passed through said discharge lamp, and during the second part of each half cycle of said low frequency alternating current, only said low frequency alternating current is passed through said discharge lamp, whereby said This is to compensate for the extinction or decrease of ions during the rest period of the overflow current of the discharge lamp to keep the discharge lamp lit. Therefore, in this method, if the supply of high-frequency current were to stop, the discharge lamp would immediately go out.

FIG. 6 is an electrical circuit diagram of one embodiment of the present invention. Power supply E is connected in parallel with a capacitor CP, which is extremely small in capacity compared to conventional power factor correction, and a power transformer is connected to the capacitor CP.
The primary winding L10 of the TR is connected in parallel. The secondary winding L20 of the power transformer TR is connected in series to the oscillating circuit R2. The filament windings H and H of the power transformer TR are the filament f of the discharge lamp FL.
1, heat f2. Further, a current limiting transformer CT is inserted between the discharge lamp FL and the primary winding L10 of the power transformer TR. One end of the primary winding W10 of the current limiting transformer CT is connected to one end of the primary winding L10 of the power transformer TR, and the other end is connected to the filament f1 of the discharge lamp FL. One end of the secondary winding W20 of the current limiting transformer CT is connected to the other end of the primary winding W10, and the other end is connected to the vibration circuit R2 via the oscillation intermittent capacitor C1.
connected to. Further, the other end of the secondary winding W20 of the current limiting transformer CT is connected to the connection point between the inductor L2 and the thyristor S via the resistor RD. Note that the primary winding W10 and the secondary winding W20 of the current limiting transformer CT are connected in a positive polarity as shown in the figure. The primary winding W10 and the secondary winding W20 are
The inductive reactance ω(L1
+L2), the difference 1/ωc-ω(L1
+L2) is useful for making the oscillation operation period of the oscillation circuit R2 appropriate, and for the discharge lamp FL, the tube current flows only through the primary winding W10, and this primary winding By making only the wire diameter of W10 thicker, we can create a current limiting transformer.
We are trying to make CTs smaller.

In the above configuration, the breakdown voltage V _BO of the thyristor S constituting the oscillating circuit R2 is the same as that of the low frequency AC power supply E.
The maximum value of the voltage applied to the thyristor S at the time of starting the discharge lamp FL by turning on the
That is, it is set smaller than the maximum value of the voltage V (L10+L20) stepped up by the power transformer TR. This ensures that the oscillating circuit R2 can start its oscillating operation.

Furthermore, the breakdown voltage V _BO of the thyristor S is determined by the voltage applied to the thyristor S before the discharge lamp FL is re-ignited every half cycle during the so-called lighting of the discharge lamp FL after the discharge lamp FL has started. It is smaller than the maximum value of the voltage, that is, the maximum value of the difference voltage between the voltage V (L10 + L20) stepped up by the power transformer TR and the terminal voltage V _C1 of the oscillation intermittent capacitor C1, and the regeneration of the discharge lamp FL every half cycle. The maximum value of the voltage applied to the thyristor S after ignition, that is, the terminal voltage V _L20 of the secondary winding L20 of the power transformer TR, the tube voltage V _T of the discharge lamp FL, and the terminal voltage V _C1 of the oscillation intermittent capacitor C1. is set larger than the maximum value of the differential voltage. By that,
In addition to ensuring the oscillation operation of the oscillation circuit R2 before re-igniting the discharge lamp FL every half cycle,
This prevents the vibration circuit R2 from malfunctioning after the FL is restarted.

Further, the discharge starting voltage or starting voltage E _ST of the discharge lamp FL is larger than the voltage of the low frequency AC power supply E, that is, the maximum value of the voltage V _L10 of the primary winding L10 of the power transformer TR, and the high frequency output generating means , that is, the sum voltage of the oscillation output voltage V _C ' of the starting circuit R2 and the terminal voltage V _C1 of the oscillation intermittent capacitor C1, and the secondary winding W of the current limiting transformer CT.
In other words, the peak value of the voltage difference between the terminal voltage V _W20 of the power transformer TR and the voltage V _L10 of the primary winding L10 of the power transformer TR and the oscillating circuit R2 obtained across the primary winding W10 of the current limiting transformer CT. High frequency oscillation voltage V
It is set smaller than the peak value of the sum voltage with _C ′. This prevents the discharge lamp FL from being started and re-ignited only by the low-frequency voltage, and also ensures that the discharge lamp FL is started and re-ignited by the sum of the low-frequency voltage and the high-frequency oscillation output voltage. It is designed to allow re-ignition every half cycle.

The operation will be explained with reference to FIG. Voltage V of the first half cycle of AC power supply (=V
Suppose that _L10 ) is supplied. This voltage V _L
10 is applied to the discharge lamp FL through the primary winding W10 of the current limiting transformer CT, but since this voltage V _L10 is lower than the starting voltage E _ST of the discharge lamp FL, the discharge lamp FL
does not light up when starting. On the other hand, power transformer TR 2
Voltage V stepped up in the next winding L20
(L10+L20) is applied to the oscillating circuit R2 via the primary and secondary windings W10 and W20 of the current limiting transformer CT and the capacitor C1. This voltage V(L10+
L20) charges the capacitor C of the oscillating circuit R2, and its terminal voltage V _C (=1/c∫dI _C dt) is applied to the thyristor S via the inductor L2, so the applied voltage of the thyristor S is V _S (=V _C ) reaches the breakdown voltage V _BO , the thyristor S breaks over, and the oscillating circuit R 2 starts to oscillate due to the cooperative action of the capacitor C and the inductor L 2 , causing a high-frequency, high-voltage oscillation voltage. Generates V _C. This oscillation voltage V _C is divided by the primary and secondary windings W10 and W20 of the current limiting transformer CT, and the primary winding W1
A divided voltage V _C ' of 0 is superimposed on the power supply voltage V _L10 and applied to the discharge lamp FL. At the same time as the oscillation operation of the oscillation circuit R2 starts, the AC power supply E-current limiting transformer CT
primary and secondary windings W10, W20 - capacitor C
A current I _C1 flows through the path of 1-vibration circuit R2-secondary winding L20 of power transformer TR-AC power supply E.
The capacitor C1 is gradually charged by this current I _C1 , and its terminal voltage V _C1 (=1/C1∫dL _C1 dt) gradually rises. Therefore, after a predetermined time of this half cycle, the terminal voltage of capacitor C1 V _C1
When reaches the power supply voltage V _L10 +L _L20 , the current I _C1 becomes zero, and the terminal voltage V _C of the capacitor C no longer reaches the breakdown voltage V _BO of the thyristor S. As a result, the thyristor S remains in the off state. Vibration circuit R
2 stops the oscillation operation. Furthermore, when the oscillating circuit R2 stops its oscillation operation, the oscillating circuit R2 becomes high impedance and the capacitor C1 does not discharge, so its terminal voltage V _C1 remains constant.

Note that since V _L10 +V _L20 =V _C1 at this time, the capacitor C1 is not discharged via the oscillation capacitor C, and since the resistor RD is also high in resistance, there is no discharge via the resistor RD.

In the next half cycle of the AC power supply E, since the terminal voltage V _C1 remains in the capacitor C1 as described above, this time the voltage V boosted by the power transformer TR
(L10+L20) and the terminal voltage V _C1 of the capacitor C1 is applied to the oscillating circuit R2. Therefore, when the differential voltage reaches the breakdown voltage V _BO of the thyristor S, the thyristor S breaks over, the oscillating circuit R2 starts to oscillate again, and the oscillating circuit R
At a predetermined time after the start of the second operation, the capacitor C1 is charged in the opposite direction to that described above, and the oscillation circuit R2 stops the oscillation operation.

Therefore, from now on, the above operation is repeated every half cycle of the AC power supply E, and the voltage and current waveforms at each part become as shown in Fig. 6A, and the oscillation voltage is set to the power supply voltage V _L10 for the discharge lamp FL. A high voltage superimposed with V _C ' is applied. At the same time, the filaments f1 and f2 of the discharge lamp FL are preheated by the filament windings H and H of the power transformer TR. In this way,
When the filaments f1 and f2 of the discharge lamp FL are sufficiently preheated and the starting voltage E _ST of the discharge lamp FL becomes lower than the applied voltage, the discharge lamp FL starts and lights up.

Even after the discharge lamp FL is started and lit, it basically operates in the same way as described above. However, when the oscillating circuit R2 starts oscillating, a superimposed voltage of the power supply voltage V _L10 and the oscillating voltage V _C ' is applied to the discharge lamp FL, and this applied voltage becomes the restriking voltage E _RST (<starting voltage) of the discharge lamp FL. Voltage E _S
T ), the discharge lamp FL is re-ignited and the discharge lamp
As a result of the terminal voltage of FL decreasing, the power transformer TR
Secondary winding L20 - discharge lamp FL - current limiting transformer CT
The voltage applied to the thyristor S through the path from the secondary winding W20 to the oscillation intermittent capacitor C1, that is, the voltage V _L of the secondary winding L20 of the power transformer TR
₂₀ , the tube voltage V _T of the discharge lamp FL, the terminal voltage V _W20 of the secondary winding W20 of the current limiting transformer CT, and the terminal voltage V _C1 of the oscillation intermittent capacitor C1. Since the voltage V _BO is no longer reached, the thyristor S is kept non-conducting;
Since the oscillating circuit R2 stops its oscillating operation, the oscillating period of the oscillating circuit R2, as shown in FIGS. 6B and 6C, is different from that in FIG. 6A at the time of startup, in that it is slightly shorter.

The secondary winding L20 of the power transformer TR in FIG. 6 is lower than the low frequency voltage V _L10 applied to the discharge lamp FL.
Low frequency voltage V (L10+
L20). By virtue of the action of the voltage V _L20 , the oscillating circuit R2 becomes operational prior to the lighting of the discharge lamp, i.e. it shifts the current waveform I _C1 of FIG. 6B in the direction of the arrow, so that the tube current changes. By accelerating the start-up, the lighting power factor of the discharge lamp FL is set to a high power factor of, for example, 0.85 or more. This secondary winding L
20 and the secondary winding W20 of the current limiting transformer CT, since the tube current of the discharge lamp FL does not flow therethrough, their current capacity is very small, and they can be formed using windings with a small wire diameter, so they are not bulky.

Based on the above results, the power supply voltage V _L10 and the discharge lamp FL
The tube voltages V _T can be very close to each other as shown in FIG. 6C, and the effective value realizes V _T ≧V _L10 . In other words, in the figure, the trapezoidal V _T
Lighting can be maintained as long as the instantaneous value at the center of the waveform is below that of V _L10 . As a result, the terminal voltage of the primary winding W10 of the current limiting transformer CT is basically eliminated. In addition, V _L10 and the tube current are almost in phase, making it possible to omit a power factor correction capacitor or achieve high power lighting with an extremely small capacity.

In general, if the terminal voltage of a current limiting device is reduced, even if it is possible to turn on the light, its impedance is small, so even a slight change in the power supply voltage will cause the tube current to fluctuate greatly, causing a problem with the current fluctuation rate, which is not practical. It is difficult. Regarding this, the secondary winding W20 of the current limiting transformer CT in FIG.
The charging current to the tube 2 exhibits an excitation effect on the transmission voltage in the direction opposite to that of the tube current, thereby improving the fluctuation rate. In other words, if the power supply voltage increases, the tube current of the discharge lamp FL will tend to increase, but
Due to the excitation effect of this tube current, the impedance of the secondary winding W20 decreases, and the inductive impedance due to the primary winding W10 and the secondary winding W20 becomes relatively large compared to the capacitive impedance due to the capacitor C1. As a result, the impedance of this series circuit increases, which delays the start of oscillation of the oscillating circuit R2, thereby delaying the timing of re-ignition of the discharge lamp FL in the next half cycle. As a result, the current fluctuation rate can be improved.

Note that the effect of the resistor RD is to stabilize the oscillation by keeping the terminal voltage of the capacitor C1 constant, especially when the discharge lamp FL is removed.

Further, in the above embodiment, the high frequency output generating means is activated prior to the discharge lamp FL by applying a voltage obtained by boosting the low frequency AC power supply voltage to the high frequency output generating means by the power transformer TR. , if the discharge starting voltage of the discharge lamp FL is higher than the breakdown voltage V _BO of the thyristor S, and the peak value of the tube voltage of the discharge lamp FL during lighting is sufficiently lower than the breakdown voltage V _BO of the thyristor S, the power transformer TR can be omitted.

This also applies to the embodiments described below. Therefore, in the present invention, the low frequency AC power supply voltage may include the secondary voltage of the power transformer TR.

FIG. 7 is an electrical circuit diagram of another embodiment of the invention. This example uses two discharge lamps FL1 and FL
2 are connected in series. For sequential lighting, a resistor R is connected in parallel with the discharge lamp FL2. The discharge lamps FL1 and FL2 are sequentially turned on in this order by the resistor R.

FIG. 8 is an electrical circuit diagram of still another embodiment of the present invention. In the embodiments described so far, the AC power supply E is set to 100V, but in this embodiment, the AC power supply E is set to 200V. As a result, the secondary winding L20 of the power transformer TR can be removed (only the transformer TR is needed).In other words, the capacitor C3 is connected in parallel to the discharge lamp FL2,
This allows the rising phase of the tube current to advance, making the secondary winding L20 unnecessary. In this embodiment, the terminal voltage applied to both ends of the primary winding W10 of the current limiting transformer CT is 75V (with respect to AC power supply E), and as in the conventional case, the terminal voltage applied to both ends of the primary winding W10 is 75V (relative to AC power supply E).
300V terminal voltage (as mentioned previously, discharge lamp 1
(150V per lamp), the terminal voltage is about 1/4th. Therefore, the VA (volt ampere) of the primary winding W10 can be reduced to 1/4. The power factor is
0.9, and the auxiliary capacitor C _P for power factor improvement as shown in FIG. 6 can also be omitted or its capacitance can be reduced. As a result, the ballast for a discharge lamp can be made considerably smaller.

FIG. 9 is an electric circuit diagram of still another embodiment of the present invention. In this example capacitor C4
The respective capacitances are determined so that the series combined capacitance of C5 and C5 is the same as that of capacitor C in the embodiments of FIGS. 6 and 8. In the embodiment shown in FIG. 8, the high frequency component generated by the oscillating circuit R2 flows through the current limiting transformer CT, the discharge lamp FL1, and the capacitor C3, thereby lighting the discharge lamp FL1.
And after the discharge lamp FL1 is lit, the high frequency component is transmitted to the discharge lamp FL via the current limiting transformer CT and the power supply E.
1 to form a closed loop. Therefore, in the embodiment shown in FIG. 8, as a result of forming such a loop, a portion of the high frequency waves leaks to the power source E. On the other hand, in the embodiment shown in FIG. 9, the high frequency component is
A closed loop is formed in FL2, that is, a loop of capacitors C5, C6 and discharge lamp FL2, first discharge lamp FL2 is lit, and then discharge lamp FL1 is lit at low frequency. This makes the high frequency component irrelevant to the AC power source E.

FIG. 10 is an electrical circuit diagram of still another embodiment of the present invention. In this embodiment, the discharge lamp FL1
A vibration circuit R2 is connected to the connection point of FL2 and FL2 via a variable capacitor CK. This allows you to change the variable capacitor CK and use the discharge lamp FL2.
The current passing through is adjusted. Such an effect can also be achieved by making the oscillation capacitor CC variable.

FIG. 11 is an electrical circuit diagram of still another embodiment of the present invention. The feature of this embodiment is that the power supply voltage is divided by capacitors C7 and C8, and the divided voltage is applied to the oscillating circuit R2. As a result, the breakover voltage V _BO of the thyristor S included in the oscillation circuit R2 can be halved, and in some cases, the oscillation intermittent capacitor C1
becomes unnecessary.

FIG. 12 is an electrical circuit diagram of still another embodiment of the present invention. The feature of this embodiment is that the discharge lamp
The oscillating circuit R2 is connected to the connection point of FL1 and FL2, thereby reducing the breakover voltage V _BO of the thyristor S of the oscillating circuit R2 by half.

To summarize the embodiments shown in FIGS. 8 to 12 above, the high-frequency discharge path generated from the oscillating circuit R2 is caused by one of the two discharge lamps being short-circuited by a capacitor at a high frequency. , at each rise of the tube current of the discharge lamp, the low-frequency discharge path from the low-frequency AC power source is activated in advance, thereby causing one of the two discharge lamps to start first, and then As a result, other discharge lamps are sequentially driven by the low frequency power source. In these cases, reducing the terminal voltage of the current limiting transformer CT and achieving high power factor lighting can be achieved by making the power supply voltage and tube voltage approximately equal. Conventionally, the oscillation circuit R2 was assumed to stop oscillating while the discharge lamp was lit, so the power supply voltage required approximately twice the tube voltage. However, according to the present invention, the maximum value, the instantaneous value of the power supply voltage, can be made equal to the instantaneous voltage at the center of the tube voltage (see FIG. 6C). For this reason, the ballast configuration requires about 1/4 of that of a conventional single yoke, making it even more compact than a sequence lighting device. Naturally, power loss is also reduced.

FIG. 13 shows another embodiment of the vibration circuit R2 used in the previously described embodiments. This resonant circuit further includes a bias winding B in series with the capacitor C. By providing the bias winding B in the magnetizing direction, the oscillation output can be increased, or by providing it in the demagnetizing direction, the oscillation output can be decreased.

Further, although the filament winding H is provided in the embodiments described above, it is also possible to use a structure without a filament winding, and the present invention can also be applied to cold cathode discharge lamps such as low-high pressure sodium lamps and halogen lamps.

As explained above, according to the present invention, the discharge lamp can be maintained lit by compensating for the disappearance or reduction of ions during the rest period of the low-frequency overcurrent of the discharge lamp by the high-frequency voltage generating means. , Contrary to the conventional starter, which was kept inactive while the discharge lamp was lit, the present invention is used as a starter for every half cycle, and moreover, the secondary winding W20 of the current limiting transformer CT is used to control the oscillating circuit R2. The impedance of the input current path is given by the inductive impedance of the primary winding W10 and the secondary winding W20, and the capacitive impedance of the capacitor C1, so that the impedance of the primary winding W10 and the capacitor C1
The inductive impedance of the primary winding W10 can be reduced by the inductive impedance of the secondary winding W20 compared to the case where the same impedance as above is obtained by _{Not only} can _the primary winding It can be constructed using copper wire with a much smaller wire diameter than W10, and in the end it can be used as a current limiting transformer.
Compared to the reduced filtering type current limiting device described in JP-A No. 49-28176, the CT can be made much smaller and lighter, achieving even greater resource and energy savings. A discharge lamp lighting device that can be made smaller and lighter can be obtained and advantageously implemented.

[Brief explanation of the drawing]

FIG. 1 shows a circuit diagram of an oscillator used in the lighting device of the present invention. FIG. 2 shows the voltage versus current characteristics of the bidirectional two-terminal thyristor used in the oscillator of FIG. FIG. 3 is a voltage and current waveform diagram illustrating the operation of the circuit shown in FIG. 1. FIG. 4 is a voltage and current waveform diagram with the time axis expanded when oscillation is stable. FIG. 5 is a circuit diagram of an embodiment of a discharge lamp lighting device which is the basis of the device of the present invention. FIG. 6 is an electrical circuit diagram of an embodiment of the one-lamp type discharge lamp lighting device of the present invention. In FIG. 6, A is a waveform diagram of each part for explaining the operation of the device in FIG.
Figures B and C are waveform diagrams for explaining the operation during lighting. 7 to 12 are electrical circuit diagrams of other embodiments of the two-lamp discharge lamp lighting device of the present invention. FIG. 13 is an electric circuit diagram of another embodiment of the vibration circuit R2. In the figure, E is a low frequency AC power supply, TR is a power transformer, W10 is a current limiting device (current limiting transformer CT
primary winding), FL, FL1, FL2 are discharge lamps, R2
is a high frequency output generating means (vibration circuit), C1 is a means for defining a high frequency output generation period (oscillation limiting capacitor), L20, C2, C3, C5+C6, C
1+CK+CC, C8+C9 are phase control means (L2
0 is the secondary winding, C2, C3, C5, C6, C1,
CK, CC, C8, and C9 are capacitors), and CT is a means (current-limiting transformer) for superimposing low-frequency alternating current and high-frequency generated power and supplying the same to the discharge lamp.

Claims (1)

[Scope of Claims] 1. A low frequency AC power supply, a current limiting device having a primary winding and a secondary winding, both windings coupled in a positive polarity, and a primary winding of the current limiting device. at least one discharge lamp connected to the low frequency AC power source through the current limiting device; and a capacitor connected to the low frequency AC power source through the primary and secondary windings of the current limiting device. It is equipped with a high frequency output generation means including an oscillating circuit configured by connecting a series circuit of an inductor and a thyristor in parallel, and a capacitor for oscillation intermittent, and the breakdown voltage of the thyristor of the oscillating circuit is set at the time of starting and during lighting of the discharge lamp. less than the maximum voltage applied to the thyristor before restriking every half cycle;
and set higher than the maximum value of the voltage applied to the thyristor after re-ignition of the discharge lamp in each half cycle, set the discharge starting voltage of the discharge lamp to be higher than the maximum value of the low frequency AC power supply voltage, and set the high frequency output A discharge lamp lighting device characterized in that the high frequency output voltage of the generating means is set to be lower than the maximum value of the applied voltage.