JPS6130400B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a chopper-type discharge lamp lighting device in which a switching device that turns on and off at a high repetition rate is interposed between a power source and a discharge lamp.

A so-called chopper type discharge lamp lighting device in which a switching device is interposed between a power source and a discharge lamp for the purpose of reducing the current limiting impedance is generally constructed as shown in FIG. That is, 1 and 2 are terminals of an AC power supply 0, and a discharge lamp 5 is connected between these terminals 1 and 2 via a ballast 3 and a semiconductor switch 4 in series. Then, the semiconductor switch 4 is controlled by the control circuit 6 to a relatively small size.
By controlling ON-OFF with ON-Duty, the lamp voltage of the discharge lamp 5 is substantially increased, thereby reducing the difference between the power supply voltage and the lamp voltage, and reducing the current limiting impedance of the ballast 3. .

However, the apparatus shown in FIG. 1 has the following drawbacks. That is, since the lamp voltage of the discharge lamp 5 and the power supply voltage are relatively close to each other, the operating point moves significantly due to fluctuations in the power supply voltage, resulting in a disadvantage that the power supply fluctuation characteristics deteriorate. One way to eliminate this drawback is to reduce the ON-Duty overall. However, when the power source is a commercial AC power source, the instantaneous value of the power source voltage changes continuously and relatively quickly, and the voltage changes significantly during a half cycle. Therefore, in such a case, if ON-Dudy is made small overall, the discharge becomes unstable in a region where the power supply voltage is low, and phenomena such as flickering or extinguishing of the discharge lamp will occur.

On the other hand, some discharge lamp lighting devices of this type have a method of sequentially switching multiple lamps at high speed to light them, but even with this method, the power supply fluctuation characteristics deteriorate significantly as the lamp voltage increases. Particularly when the power source is a pulsating current power source or an alternating current power source, there is a drawback that the lamp may flicker. U.S. Patent No. 3,824,428 discloses a method of changing the pulse width according to fluctuations in the power supply voltage.
This is merely a means for suppressing fluctuations in optical output, and is not aimed at stabilizing the discharge, particularly against voltage changes during a half cycle of the power supply.

Furthermore, as a discharge lamp lighting device of this type, there is a device (patent filed by Matsushita Electric Works) in which a plurality of discharge lamps are sequentially operated in conjunction with each other to light them, thereby improving the input power factor. This is so that the lighting operation of the first light controls the lighting of the second light, and the lighting action of the second light controls the lighting of the third light, and so on. Therefore, if even one discharge lamp is not lit, other discharge lamps are also affected.

The present invention was made in consideration of these various circumstances, and by controlling the ON period of a switching device installed between the power supply and the discharge lamp according to the instantaneous value of the power supply voltage, it is possible to control the type of power supply. An object of the present invention is to provide a discharge lamp lighting device capable of stably starting and lighting a discharge lamp, regardless of the type and number of discharge lamps, and capable of minimizing stability factors. .

Hereinafter, details of the present invention will be clarified with reference to embodiments shown in the drawings. FIG. 2 is a diagram showing a schematic configuration of an embodiment of the present invention. In Fig. 2, 10 is a power supply, and a low impedance ballast 13 is connected between terminals 11 and 12 of this power supply 10, and a low impedance stabilizer 13 is connected to the ON--
A discharge lamp 15 is connected in series with a switching device 14 that is turned off. Note that the permissible range of the above-mentioned high repetition frequency is conceptually several kHz or more, and there is no upper limit. However, in practice, setting the frequency below 20kHz falls into the audible frequency range, which is undesirable as various types of humming sounds can be heard. Moreover, it is actually difficult to operate at 100 kHz or higher due to the switching speed of the switching element, and problems such as radio frequency interference may occur, so it would be impossible to operate at 200 kHz or higher. Second
In the figure, 16 is a control device that changes the ON period of the switching device 14 according to the instantaneous value of the voltage of the power source 10. The change in ON period here means ON-Duty or ON
-Includes both changes in OFF repetition frequency.

FIG. 3 is a diagram showing an example of the specific circuit shown in FIG. 2 above. Therefore, parts corresponding to those in FIG. 2 are given the same reference numerals as in FIG. 2. In this FIG. 3, the power supply 10 is an AC power supply, and the ballast 1
3 is a current limiting resistor. The switch section 14a inserted between the power source 10 and the discharge lamp 15 constitutes the switching device 14 shown in FIG. 2, together with a drive section 14b that turns the switch section 14a on and off. The switch part 1a is 4
A diode bridge consisting of diodes D1, D2, D3, and D4, and an NPN transistor connected between the DC output terminals of this diode bridge.
It consists of TR. Further, the drive section 14b is
The main parts are an oscillator 22 and a monostable multivibrator 28 that operates using the output of the oscillator 22 as an input signal. The oscillator 22 is programmable.
It is composed of a unidirectional transistor 23, resistors 24, 25, 26, and a capacitor 27, and sends out a trigger pulse at a predetermined period determined by the time constant of a time constant circuit of the resistor 24 and capacitor 27. It's becoming like that. The monostable multivibrator 28 is triggered by a trigger pulse from the oscillator 22 and sends out a pulse with a predetermined width, and the pulse width is controlled by a control device 16, which will be described later. The output pulse of the monostable multivibrator 28 is passed through a current amplifier 32 to the NPN voltage of the switch section 14a.
It is added between the base and emitter of transistor TR. Current amplifier 32 is NPN transistor 33
is used as an amplifying element, and the pulse output from the monostable multivibrator 28 is supplied to the base of this transistor 33 via a parallel circuit of a capacitor 34 and a resistor 35. The collector current of the transistor 33 is taken out between terminals a and b by a pulse transformer 36, and is applied between the base and emitter of the transistor TR of the switch section 14a.

By the way, the control device 16 includes a voltage detection device consisting of a transformer 20 connected to the power source 10 and a full-wave rectifier circuit 21 connected to the transformer 20, and a resistor 29, a PNP transistor 30, and a capacitor 31 connected to this device. It consists of a bias device consisting of, etc. That is, this control device 16 uses the voltage detection device to detect the instantaneous value of each half-wave of the power supply voltage, and uses the bias device to apply a predetermined bias to the monostable multivibrator 28 according to the detected instantaneous value. By changing the time constant of the monostable multivibrator 28, the ON period, that is, the pulse width of the output signal sent from the monostable multivibrator 28 is changed. In other words, this control device 16 changes the ON period without changing the ON-OFF repetition frequency of the switching device 14.

The circuit of FIG. 3 constructed as described above operates as follows. When the oscillator 22 is operated, a pulse with a predetermined period is applied to the input terminal of the monostable multivibrator 28 to trigger it. Therefore, the monostable multivibrator 28 starts operating. When the power supply 10 is turned on in this state, a sine wave AC voltage as shown in FIG. 4a is sent out from the power supply 10. This power supply voltage is detected as an instantaneous value for each half-wave by a voltage detection device consisting of a transformer 20 and a full-wave rectifier circuit 21, and is then passed through a monostable bias device consisting of a resistor 29, a transistor 30, and a capacitor 31. It is applied to the bias input terminal of the multivibrator 28 as a bias voltage for time constant control. Therefore, the monostable multivibrator 28 sends out an output signal having a pulse width corresponding to the instantaneous value of the power supply voltage. After this output signal is amplified by the current amplification circuit 32, the output signal is
A forward bias voltage is applied between the base and emitter of the This voltage is a pulse voltage whose pulse width varies depending on the magnitude of the power supply voltage, as shown in FIG. 4b. Therefore, the transistor TR turns ON and OFF according to the pulse voltage. Therefore, in the discharge lamp 15, the above transistor TR is turned on.
A pulsed AC voltage corresponding to the OFF operation is applied to turn on the light. FIG. 4c shows the lamp voltage waveform of the discharge lamp 15, and FIG. 4d shows the lamp current waveform. As can be seen from these waveforms, the fourth
In each half-wave of the power supply voltage waveform shown in Figure a, the ON-Duty increases at low voltage points, causing the lamp voltage to drop. In addition, the ON-Duty decreases at high voltage points during each half-wave, substantially increasing the lamp voltage. As a result, the discharge lamp 15 lights stably without flickering. Figure 5 shows how the lamp voltage decreases when ON-Duty is large, and increases when ON-Duty is small.

Figure 5 shows the FL40S fluorescent lamp turned on using a DC power supply and the switching device at a repetition frequency of 20KHz.
- FIG. 7 is a diagram showing the experimental results of the relationship between the lamp voltage V _LP and the lamp current I _LP when the lamp is operated in the OFF state.
As is clear from Fig. 5, the current peak value I _LP
When compared with constant ON-Duty of 100% and 50
%, 33%, and 25%, the lamp voltage increases. This phenomenon is thought to be due to the fact that when the ON-Duty is reduced, the ionization period of ions in the discharge lamp becomes shorter than the ion recombination period, and the lamp voltage increases accordingly. Therefore, depending on the instantaneous value of the pulsating power supply voltage, the ON-
By reducing the duty, the lamp voltage increases and can be brought close to the instantaneous value of the power supply voltage. In other words, in parts where the instantaneous value of the power supply voltage is large, the lamp voltage can be increased so as to approach the instantaneous value of the power supply voltage, and in parts where the instantaneous value of the power supply voltage is small, the lamp voltage can be increased much more than the instantaneous value of the power supply voltage. It can be lowered. Therefore, the discharge lamp can be stably started and lit using a small, low-impedance ballast. This can also be understood from the experimental waveforms shown in FIG. Note that the curve showing the constant power line is shown in Figure 5, but this is a plot of the constant power point under each condition shown in the figure when a DC power source is used as the power source. It does not indicate the power under each instantaneous value when used.

The power supply circuit of the circuit shown in FIG. 3 is, for example, as shown in FIG. 6, in which a pulsating current is supplied by a non-smoothed DC power supply in which a full-wave rectifier 40 is connected to an AC power supply 10. But that's fine. In the case of a device equipped with such a power supply circuit, a transistor is used as the switch portion 14a of the switching device.
The TR can be directly connected in series with the discharge lamp 15, and a voltage dividing circuit 43 in which resistors 41 and 42 are connected in series can be used as means for detecting the power supply voltage.

FIG. 7 is a block diagram showing another embodiment of the present invention. In this embodiment, the terminals 51 and 52 of the power supply 50 are
For example, a plurality of low impedance stabilizers 53 and switching devices 54 are connected in series between them.
~10 discharge lamps 55a, 55b, 55c... are connected in parallel. Switching device 54
is a plurality of switch parts 54a, 54b, 54c... connected in series to each discharge lamp, respectively;
It is composed of a driving section (not shown). However, this switching device 54 is
4a, 54b, 54c...
5a, 55b, and 55c are alternately connected to the power source 50. The switching device 54
A control device 56 that controls the ON period is configured to change the ON period by changing the repetition frequency of the switching device 54 in accordance with the instantaneous value of the power supply voltage.

Figure 8 a, b, c, d are the power supplies 5 of the circuit in Figure 7.
0, the DC power supply is connected, and the waveforms of each part are shown when there are three discharge lamps and three switch parts each. a is the power supply voltage, b is the discharge lamp 55a, 55
The voltage across the lamp of b, 55c, X, Y,
Z corresponds to the lamp voltage of each discharge lamp. c indicates the lamp current of the discharge lamps 55a, 55b, and 55c, and its envelope corresponds to the current flowing from the power source 50. d indicates the voltage across the ballast 53, the magnitude of which is obtained by subtracting the sum of the lamp voltages of the discharge lamps 55a, 55b, and 55c from the power supply voltage shown in a of the figure. As can be seen from FIG. 8, if the power supply voltage increases by ΔV ₁ at time t ₁ , the control device 56 shortens the ON-OFF cycle of the switch sections 54 a, 54 b, and 54 c. That is, the repetition frequency of the switching device 54 increases. Therefore, for reasons to be explained later, the voltages X, Y, and Z across the lamp rise by ΔV ₂ , keeping the lamp power constant and increasing the ballast 5.
Suppress the increase in VA (or W) borne by 3.

9a and 9b show the waveforms of various parts when an AC power source is connected as the power source 50 of the circuit in FIG. This is the voltage waveform across 55b and 55c. Further, b is a voltage waveform across the ballast 53. As is clear from FIGS. 9a and 9b, the repetition frequency of the switching device is high near the peak value in each half-wave of the AC power supply voltage, that is, in the high voltage region, and the repetition frequency of the switching device is high near the zero level, that is, in the low voltage region. The repetition frequency of the device is getting lower. When the repetition frequency of the switching device becomes higher, the lamp voltage becomes higher even if the ON-Duty is the same, so a current suppressing effect occurs and the ballast 53 can be made smaller. The reason for this will be explained below.

Figure 10 shows a DC power supply connected to the circuit in Figure 7,
When using a fluorescent lamp FL40S as a discharge lamp
This figure shows the actual measured values of the lamp voltage V _LP and lamp current I _LP of FL40S. If the lamp power is constant 40W, the repetition frequency is 10KHz, 20KHz,
As the frequency increases to 50KHz, the lamp voltage V _LP increases. Although the details of the reason for this are not clear, it is thought that this occurs because the ion and electron density in the plasma changes due to the intermittent current. From this figure, it is possible to increase the lamp voltage by increasing the frequency in areas where the instantaneous value of the power supply voltage is large, and by lowering the frequency in areas where the instantaneous value of the power supply voltage is small. It can be seen that the lamp voltage can be lowered. On the other hand, the reason why the VA of the ballast, which is closely related to the size of the ballast, is reduced by configuring it as shown in FIG. 7 will be explained below using a specific example.

Let us consider the case where the power supply is DC V _S =200V and three FL40S lights are lit at the rated value of 40W.
When DC is lit, I _LP - V _LP when DC is lit as shown in Figure 10.
Referring to the curve, since V _LP =106V and I _LP =0.375A, the power consumption W _DC of the ballast (in the case of a resistor) is as follows.

W _DC = (V _S - V _L ) x I _L x n = (200 - 106) x 0.375 x 3 = 106 (W) On the other hand, configure the circuit as shown in Figure 7 and set the repetition frequency to 10 KHz to use FL40S3 lamps. When the are turned on sequentially with a pulse width of 33 μs, referring to the I _LP - V _LP curve at = 10 KHz in Figure 10, V _L = 135 V and I _V = 0.9 A, so the consumption of the ballast is The electric power W is expressed by the following formula.

W = (V _S - V _L ) x I _L = (200-135) x 0.9 = 58.5 (W) Therefore, by configuring as shown in Figure 7, the power consumption of the ballast 53 is reduced compared to when DC lighting is performed. Approximately 50%
Decrease. It will be understood from this example that if the repetition frequency is further increased, the power consumption will be further reduced. It will also be understood that the VA of the ballast 53 decreases in the case of an AC power supply as well as in the case of a DC current.

When the difference between the power supply voltage and the lamp voltage becomes smaller,
It is a well-known fact that the size or VA of the ballast decreases, but in general, when the power supply voltage is reduced to approach the lamp voltage, the restriking voltage becomes insufficient and the discharge becomes unstable.

However, in the case of this device, instead of changing the power supply voltage, the switch parts 54a, 54b, 5
Since the lamp voltage is controlled by changing the ON-OFF cycle of 4c, that is, the repetition frequency, according to the instantaneous value of the lamp voltage, there is an advantage that the power supply fluctuation characteristics can be significantly improved.

FIG. 11 shows a specific circuit diagram of FIG. However, this is a case where the number of discharge lamps and switch parts is three each. In FIG. 11, a power source 50 is a commercial AC power source, and 53 is a stabilizer using, for example, an inductance. 55a, 55b, 55c
is a discharge lamp, and 54a, 54b, and 54c are switch parts using diode bridges and transistors, and are turned on and off by signals input to a, a', b, b', and c, c', respectively. controlled. The control device 56 includes a voltage detection device consisting of a transformer 61 connected to the power source 50 and a full-wave rectifier circuit 62 connected to the transformer 61, and a clock pulse generation circuit 63 whose frequency changes according to the output of the voltage detection device. The clock pulse is sent to a ring counter 64, which will be described later. The clock pulse generator 63 has an oscillator composed of a programmable conjunction transistor 73, resistors 79, 81, 82, and a capacitor 80, and a time constant circuit of this oscillator, that is, a series circuit of a resistor 79 and a capacitor 80. It is composed of two transistors 68 and 69 that are variably controlled according to the power supply voltage. The NPN transistor 68 connected between the DC output terminals of the one transistor, that is, the full-wave rectifier circuit 62, amplifies the output of the rectifier circuit 62, and the NPN transistor 68 connected in parallel with the resistor 79 of the time constant circuit. Transistor 69 is the above
The degree of conductivity is variably controlled by the output of the NPN transistor 68, thereby changing the time constant of the time constant circuit in accordance with the instantaneous value of the power supply voltage.

The ring counter 64 includes the switch portion 54a,
It constitutes the switching device 54 together with 54b and 54c, and at least the discharge lamp 55
J-K with the number of stages corresponding to the numbers of a, 55b, 55c
Flip-flops 76, 77, 78 and a NAND circuit 7 connected between these flip-flops
It consists of 4,75. However, the ring counter 64 is connected to the clock pulse generating circuit 63.
The switch section 54 is operated in response to a variable frequency clock pulse supplied from the switch section 54, and outputs from each stage are sent to the switch section 54 via current amplifying circuits 65, 66, and 67, respectively.
In addition to the switch sections 54a, 54b, and 54c, these switch sections 54a, 54b, and 54c are alternately controlled to turn on and off. The current amplification circuits 65, 66,
67 are NPN transistors 70, 71, 72, respectively.
is used as an amplifying element, and its amplified output is passed through pulse transformers 90, 91, 92 to switch sections 54a, 5.
The voltage is applied between the base and emitter of each transistor 4b and 54c.

The circuit configured as shown in FIG. 11 operates as follows. When the power source 50 is turned on, the AC voltage of the power source 50 is applied to each discharge lamp 55a, via the ballast 53.
55b and 55c at the same time. However, each discharge lamp has switch parts 54a and 5, respectively.
4b and 54c are connected in series and operate sequentially as described below.
- Voltages corresponding to the OFF operation are applied sequentially. That is, the voltage of the power supply 50 is detected by a voltage detection device consisting of a transformer 61 and a full-wave rectifier circuit 62, and this is detected by a voltage detection device consisting of a transformer 61 and a full-wave rectifier circuit 62.
After being amplified by , it is applied between the base and emitter of the PNP transistor 69 . The transistor 69 therefore changes its conductivity in response to the voltage change or instantaneous value of each half-cycle of the supply voltage. Therefore, the time constant of the time constant circuit of the clock pulse generating circuit 63 is variably controlled in accordance with the degree of conductivity of the transistor 69. Therefore, the clock pulse generating circuit 63 sends out a clock pulse having a frequency corresponding to the instantaneous value of the power supply voltage.

Now, it is assumed that the instantaneous change in the power supply voltage shifts from a relatively high voltage to a low voltage as shown in FIG. 12a. Then, the clock pulse generation circuit 6
As shown in Figure 12b, clock pulses of relatively high frequency are sent out from 3 in the region where the power supply voltage is relatively high (the left half in the figure), and clock pulses with a relatively high frequency are transmitted in the region where the power supply voltage is relatively low (the right half in the figure). half), relatively low frequency clock pulses are sent out. When such a clock pulse is input to the ring counter 64, the counter 64 operates at a speed corresponding to the frequency of the clock pulse. Therefore, the outputs of each stage of the ring counter 64, that is, the JK flip-flops 76, 77, 78
The respective Q outputs are as shown in FIG. 12c, d, and e. That is, in a region where the power supply voltage is high, pulses having a relatively short period _T1 and approximately the same width as the clock pulse are repeatedly sent from each stage. Further, in a region where the power supply voltage is low, pulses having a relatively long period _T2 and a wide width are repeatedly sent out from each stage in sequence. These pulses are amplified by current amplifier circuits 65, 66, and 67 for each stage output, and become pulse currents as shown in FIG.・Added between the vines. Therefore, the switch parts 54a, 54b, 54c
According to the pulse current waveform, each transistor operates on and off at a large repetition frequency in the region of high current and voltage, as shown in Figure 12 i, j, and k, and turns on at a small repetition frequency in the region of low power supply voltage.
- OFF works. Therefore, each discharge lamp 55a, 5
5b, 55c have the above-mentioned switch parts 54a, 54.
The voltage shown in FIG. 12a is applied during the ON period corresponding to the ON-OFF operation of 54b and 54c. As a result, the discharge lamps 55a, 55b, 55
c will be lit, but as mentioned above, in the region where the power supply voltage is high, the switch parts 54a, 54b,
Since the repetition frequency of 54c is high, the lamp voltage increases, and conversely, in a region where the power supply voltage is low, the repetition frequency of the switch section is low, so the lamp voltage does not increase. For this reason, each discharge lamp 55a, 55b, 55c
A substantially constant power is supplied to the discharge lamp regardless of changes in the power supply voltage, and the discharge lamp is stably lit. Therefore, the VA of the ballast 53 may be small, and the ballast 53
can be made smaller. The fact that the ballast 53 can be made smaller means that its inductance is smaller, so the capacitor for power factor correction can also be of smaller capacity.

On the other hand, the current flowing through the ballast 53 is a continuous current, so unless there is an unlit discharge lamp,
There is no risk of a spike voltage occurring in the ballast 53. In the circuit shown in FIG. 11, the capacitor 83 is connected to both ends of the circuit in which the discharge lamp and the switch section are connected in series, so even if a discharge lamp goes out, the resulting spike voltage will be absorbed by the capacitor 83. Absorption will be limited by
The capacitor 83 also contributes to the prevention of noise generation in relation to the inductance of the ballast 53.

When the power consumption of the ballast, that is, the ballast 53 of the apparatus manufactured as in the embodiment shown in FIG. 11 was measured, it was 12 W or less. Further, the power consumption of the control device 56 was about 3W. Therefore, the total power consumption is about 15W. Comparing this with the conventional method, for example, when three FL40S lights are lit with a single-ch yoke, it can be seen that it is extremely advantageous. That is, in the conventional type, the power consumption of the ballast is 8.35W x 3 = 25.05W, so the power consumption in the present embodiment is about half that of the conventional type. If the number of discharge lamps increases, the ballast 53 can be made even smaller. For example, when the number of lights becomes about 8, the ballast 53 is no longer necessary, and the power consumption becomes only the total power consumption of the control device 56 and the switching loss of the transistors of each switching section 54a, 54b, 54c in the switching device 54. Calculating the power consumption in this case, the power consumption of the control device 56 is 3W and the switching loss of the transistor is 3W×8=24W, so the total power consumption is 27W. When 8 lights are turned on using the conventional method, the power consumption is 8.35W x 8 = 66.8W, which is less than 50% of the conventional method.

In addition, to eliminate ballast, use discharge lamp 1.
It is necessary to set the light ON-Duty relatively small. For example, in the case of FL40S, it needs to be 10 to 15% or less. Therefore, in order to configure the system so that the input current is continuous, it is desirable to sequentially switch and light about 6 to 10 discharge lamps. Therefore, when controlling the lighting of 10 or more lights without ballast,
It is preferable to provide 6 to 10 sets of multiple lights connected in parallel, and to switch these lights on in sequence.

FIG. 13 shows an example. i.e. 55a-1, 55a-2 and 55b-1, 5
5b-2, 55c-1, 55c-2, . . . each indicate a plurality of sets of discharge lamps connected in parallel. These discharge lamp groups are controlled by switch sections 54a, 54b, 54 controlled by a control device 56.
c, the lights are sequentially connected to the power source and the lighting is controlled. Note that the switch parts 54a, 54b, 54c change depending on the change in the power supply voltage.
For those that perform ON-OFF repetition frequency control, in order to absorb variations in characteristics between each discharge lamp, a small inductance 53' of, for example, several mH, is connected to the power supply as shown in Figure 13. It is effective to insert the lamp in series between the lamp and the discharge lamp group.

Furthermore, in addition to transistors, thyristors, triacs, gate turn-off thyristors, etc. can also be used for the switch parts 54a, 54b, and 54c, and the configuration of the control circuit is not limited to the embodiment shown in FIG. 11, but may have the same functions. Anything is fine as long as it has the following. In addition, when a thyristor is used in the switch part, a well-known method for turning off the thyristor is to use a well-known thyristor ring counter as shown in "SCR and its Applications" (published by Nikkan Kogyo Shimbun) in the switch part. do it. That is, it is sufficient to configure a ring counter including a plurality of thyristors connected in series with each discharge lamp as a component. In this way, the thyristors can be sequentially controlled to turn on and off by simply supplying a pulse train of a predetermined period from the control device 56. Further, when using a thyristor as the switch section, if the power source is an AC power source, this can be easily implemented by connecting a pair of thyristors in antiparallel and applying a gate signal via a pulse transformer.

Furthermore, in the embodiment shown in FIG. 11, the switching device is controlled by changing the frequency of the clock pulse so that it is approximately proportional to the magnitude of the power supply voltage, but in order to increase the input power factor, The current waveform may be controlled to approximate the power supply voltage waveform.

As a means for approximating the input current waveform to the power supply voltage waveform, for example, a current transformer is inserted in series in the power supply line, the current value supplied from the power supply is detected by this transformer, and this detected current value and the value shown in FIG. The PNP transistor 6 shown in FIG.
Means for variably controlling the degree of conductivity of 9 can be considered.

Further, in the embodiment shown in FIG. 11, an inductance is used as a stabilizing element, but a capacitor, a resistor, or a combination of these impedances may be used as a stabilizing element. As for the number of discharge lamps, as is clear from what has already been said, it is possible to use any number of discharge lamps, and of course, it is also possible to use one lamp.

In this way, in the embodiments shown in FIGS. 7, 11, and 13, a plurality of series circuits of the switch section and the discharge lamp are connected in parallel, and connected to the power supply via impedance, and the switch section and the discharge lamp are connected in parallel. Since the parts are turned ON and OFF sequentially, and the repetition frequency of this ON and OFF is changed according to the instantaneous value of the power supply voltage, it is possible to increase the lamp voltage and make the stability factor very small or even zero. By controlling the lamp voltage, the fluctuation characteristics can be greatly improved, and the discharge lamp can be lit stably. Furthermore, regardless of the type of stabilizing element, the input current waveform can be freely formed to effectively increase the input power factor, there is no need to use other elements for power factor improvement, and the overall design is small, lightweight, and An inexpensive multi-lamp lighting circuit can be obtained. Furthermore, when controlling the frequency so that the input current is continuous, there is an advantage that all ballast elements such as resistors, capacitors, and inductances can be used compared to the pulse width (ON-Duty) control method. However, since variable control for each discharge lamp is difficult, it is necessary to provide a means to balance each discharge lamp by inserting a small inductance between the power supply and the discharge lamp, as described above.
Note that it can also be used in conjunction with the ON-Duty control method. When used in conjunction with the ON-Duty control method, it is possible to easily stabilize discharge in areas where the power supply voltage is low, and it is also possible to eliminate ballasts even when there are few discharge lamps, such as only two lamps. become.

As explained above, the present invention inserts a switching device that turns ON and OFF at a high repetition frequency between a power source and a discharge lamp, and a control device controls the ON period of the switching device according to the instantaneous value of the power supply voltage. This is a discharge lamp lighting device that can change the ON period so that it becomes smaller in the portion where the instantaneous value is large. When the above configuration is taken as the basic configuration (a), the present invention includes the following embodiments.

(b) The discharge lamp lighting device according to (a) above, wherein the control device changes the ON period by changing the repetition frequency of the switching device according to the instantaneous value of the power supply voltage.

(c) The discharge lamp lighting device according to (a) above, wherein the control device changes the ON period without changing the repetition frequency of the switching device according to the instantaneous value of the power supply voltage.

(d) The discharge lamp lighting device of (a) to (c) above, wherein the power source is a non-smoothed direct current power source comprising an alternating current power source and a full-wave rectifier whose input end is connected to the alternating current power source.

(E) The switching device includes an oscillator, a monostable multivibrator that uses the output of the oscillator as an input signal, and a transistor inserted in series between the power source and the discharge lamp and controlled by the vibrator. Featured above
The discharge lamp lighting device of (a) to (d).

(f) The switching device includes an oscillator, a monostable multivibrator that uses the output of the oscillator as an input signal, and a transistor that is inserted in series between the power source and the discharge lamp and is controlled by the output of the vibrator. The control device includes a voltage detection device that detects the instantaneous value of the power supply voltage, and turns on the output signal of the monostable multivibrator according to the output of this voltage detection device.
The discharge lamp lighting device according to (a) above, comprising a bias device for controlling a period.

(G) The discharge lamps include a plurality of units, each of which is connected in parallel to the power source, and the switching device includes a plurality of switch units connected in series with each discharge lamp, It is characterized by comprising a shilling counter having a number of stages corresponding to at least the number of the discharge lamps and sequentially supplying the output of each stage to each of the switch parts and controlling each switch part alternately on and off. The discharge lamp lighting device of (a) above.

(h) The control device is configured to control the switching device according to the instantaneous value of the power supply voltage by detecting the current supplied from the power supply. ) discharge lamp lighting device.

(li) The discharge lamp is a plurality, and each of the discharge lamps is connected in parallel to the power source,
The discharge lamp lighting device according to (a) or (h) above, wherein the switching device comprises a ring counter including as a component a plurality of thyristors connected in series with each discharge lamp.

(n) There are 6 to 10 discharge lamps, each of which is connected in parallel to the power source,
The discharge lamp lighting device described in (a) to (d) and (g) to (i) above, wherein the switching device operates to alternately connect the power source to each discharge lamp.

Therefore, according to the present invention, a switching device that is inserted between a power source and a discharge lamp and turns on and off at a high repetition frequency is controlled so that its ON period changes in accordance with the instantaneous value of the power source voltage. Therefore, even if the power source changes continuously and drastically during one cycle, such as an AC power source or an unsmoothed DC power source, and regardless of the type or number of discharge lamps, the discharge lamp can be used. It is possible to provide a discharge lamp lighting device that can stably light the lamp without flickering or turning off, and can also minimize the stability factor.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a schematic configuration of a conventional device, FIG. 2 is a block diagram showing a schematic configuration of an embodiment of the present invention, and FIG. 3 is a diagram showing a specific circuit configuration of the same embodiment. , Fig. 4 a, b, c, and d are waveform diagrams for explaining the operation of the same embodiment, Fig. 5 is a lamp current-lamp voltage characteristic diagram for explaining the action of the same embodiment, and Fig. 6
The figure shows a modification of the power supply circuit shown in FIG. 3, FIG. 7 is a block diagram showing a schematic configuration of another embodiment of the present invention, and FIGS. Waveform diagrams for explaining the operation when a DC power source is used as the power source, Figures 9a and b are waveform diagrams for explaining the operation when an AC power source is used as the power source in Figure 7, and Figure 10 is a waveform diagram for explaining the operation when an AC power source is used as the power source in Figure 7. 11 is a diagram showing the specific circuit configuration of FIG. 7, FIG. 12 is a waveform diagram for explaining the operation of FIG. 11, and FIG. 13 is a diagram showing lamp current-lamp voltage characteristics to explain the operation. 7 is a block diagram showing a partially modified example of FIG. 7. FIG. 10,50...power supply, 13,53...ballast (low impedance) 14,54...switching device,
15,55...discharge lamp, 16,56...control device.

Claims (1)

[Scope of Claims] 1. A power supply that outputs a periodically pulsating voltage, a discharge lamp energized from this power supply, a ballast inserted between this discharge lamp and the above power supply, and the above power supply. and the above discharge lamp at a high repetition frequency.
A switching device that turns ON and OFF, and a control device that changes the repetition frequency or ON-Duty of the switching device according to the instantaneous value of the pulsating voltage of the power supply so that the ON period becomes small in the portion where the instantaneous value is large. A discharge lamp lighting device characterized by comprising: 2. The discharge lamp lighting device according to claim 1, wherein the power source is a non-smoothed DC power source comprising an AC power source and a full-wave rectifier whose input end is connected to the AC power source. 3. The switching device includes an oscillator, a monostable multivibrator using the output of the oscillator as an input signal, and a transistor inserted in series between the power source and the discharge lamp and controlled by the vibrator. A discharge lamp lighting device according to claim 1 or 2. 4. The switching device includes an oscillator, a monostable multivibrator using the output of the oscillator as an input signal, and a transistor inserted in series between the power source and the discharge lamp and controlled by the output of the vibrator. , the control device includes a voltage detection device that detects the instantaneous value of the power supply voltage, and a bias device that controls the ON period of the output signal of the monostable multivibrator according to the output of the voltage detection device. A discharge lamp lighting device according to claim 1, characterized in that: 5. The discharge lamp is a plurality, and each of the discharge lamps is connected in parallel to the power source, and the switching device includes a plurality of switch parts connected in series with each discharge lamp, and at least the discharge lamp. A ring counter having a number of stages corresponding to the number of electric lights, and a ring counter that sequentially supplies the output of each stage to each of the above-mentioned switch parts and turns each switch part on and off alternately. The discharge lamp lighting device according to scope 1. 6. A plurality of the discharge lamps are each connected in parallel to the power source, and the switching device includes a plurality of thyristors connected in series with each discharge lamp as a component. 2. The discharge lamp lighting device according to claim 1, comprising a ring counter. 7 The number of the discharge lamps is 6 to 10, each of which is connected in parallel to the power source, and the switching device operates to alternately connect the power source to each discharge lamp. Claims 1 and 2 are characterized in that:
5. The discharge lamp lighting device according to any one of Items 5 and 6.