JP2002352992A - Lighting device for discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device which can restrain electrical stress against switching elements and inductors using a simple control circuit and prevent parts from increasing in cost and enlarging their sizes to control measure for changes in source voltage, light adjustment or the like, while conducting frequency modulation. SOLUTION: The discharge lamp lighting device 1 comprises a high-frequency power source part formed by an one-element type voltage resonance circuit having a first switching element SW1, a power source adjustment part for adjusting output from a DC power source E to the high-frequency power source part by a switching operation of a second switching element SW0 and a load circuit, including a discharge lamp RL to which high-frequency power from the high-frequency power source part, is supplied. A control unit 2, which makes the turn-off time and turn-on time of a switching operation of the first switching element SW1 fixed and variable, respectively, and makes at simultaneous turn-on period during which the turn-on time of the switching operation of the second switching element SW0 overlaps the turn-on time of the first switching element SW1 a prescribed length is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device.

[0002]

2. Description of the Related Art Conventionally, as a high-frequency power supply unit of a discharge lamp lighting device for lighting a discharge lamp at a high frequency, there is a single-stone inverter circuit type as shown in FIG. The circuit shown in FIG. 3A has a general circuit configuration as a one-piece inverter circuit. When the switch element SW1 is on, a current flows from the DC power supply E to the inductor Lo to accumulate current energy, and the switch element SW1 is turned on. Is turned off, the current energy stored in the inductor Lo is sent to the discharge lamp RL on the load circuit side to perform a quasi-E or E-class operation. Therefore, the circuit configuration is simple and easy to control, and the boosting effect on the voltage of the DC power supply E is high. Further, by adjusting the on-time of the switch element SW1, that is, the duty (the ratio of the on-time to one cycle) by the PWM control, it is easy to stabilize the output with respect to the voltage fluctuation on the DC power supply E side.

[0003] Also, as shown in FIG. 1B, a discharge lamp RL that responds to a larger fluctuation in the power supply voltage or is a lighting load.
There is also a circuit configuration in which a circuit for varying an input voltage to an inverter circuit serving as a high-frequency power supply unit is added for the purpose of dimming lighting of the device. In this case, the second switch element SW is set so that the input voltage to the inverter circuit has a predetermined value.
PWM changing duty of switching operation of 0
By controlling, it is possible to cope with a larger voltage fluctuation of the DC power supply E. Further, by appropriately adjusting the value of the input voltage to the inverter circuit, the dimming lighting of the discharge lamp RL is possible.

[0004] In recent years, it has become indispensable to suppress electromagnetic wave noise emitted from an electric device in an environment in which the electric device is used. The discharge lamp lighting device driven at a high frequency is no exception, and one of the major issues is to reduce the noise of the discharge lamp lighting device.

As an effective means for reducing the noise, it has been proposed to randomize the oscillation frequency of the inverter circuit or perform frequency modulation by sweeping the inverter circuit. For example, in the literature (T. Ninomiya,
et al: Tech. Meeting on Semi
conductor Power Conversio
n, IEEE of Japan, SPC-91-75,
Dec. 1991) shows that noise can be reduced equivalently by random control of the switching frequency in the discharge lamp lighting circuit of the voltage resonance type inverter. In this document, the reference oscillation frequency f
= The frequency modulation width Δf is about 10 kHz for about 30 kHz.
It is also shown that the noise reduction effect increases as the frequency is increased to about Hz.

[0006]

For the purpose of noise reduction, the present applicant has tried the frequency modulation operation of the oscillation frequency in the discharge lamp lighting circuit of FIG.
In the case of FIG. 7A, the inverter circuit performs a quasi-E or E-class operation, and the voltage waveform when the switch element SW1 is turned off is a voltage waveform when the current energy stored in the inductor Lo is sent to the load circuit side. The resonance voltage waveform is determined by the circuit constant. Also, this switch element SW1
It is preferable to realize zero volt switching to reduce switching loss. Therefore, it is not appropriate to change the off time when adjusting the duty of the switch element SW1. That is, the switching element SW
As a means for modulating the oscillation frequency of the first switching operation, the duty is adjusted by changing the ON time of the switch element SW1. In the above trial,
In the circuits of FIGS. 6A and 6B, the switching element SW
The reference frequency f is set to 30 kHz in order to perform the duty modulation by the ON time change of 1 and the frequency modulation operation of the oscillation frequency.
And the modulation width Δf was changed in the range of 10 kHz. In this case, the output of the high-frequency power changes due to frequency modulation, but the averaged output is changed to the reference frequency f = 30 kHz.
Is the same as when

However, it has been found that there are the following problems. When the frequency modulation operation is performed in the circuit configuration of FIG. 6A and the oscillation frequency is lower than the reference frequency as shown in FIG. 7 (see FIG. 7C), the switching operation of the switch element SWl is performed. The on-time is longer than when the frequency is the reference (see FIG. 7A). As a result, the peak value of the current flowing through the switch element SW1,
And the peak value of the voltage generated in the switching element SW1 is much larger than that at the time of the reference frequency. Therefore, in performing the frequency modulation, it is necessary to use a switch element SW1 having a large current rating and a large voltage rating, which increases the cost of the switch element SW1. Further, the current flowing through the inductor Lo also increases. Therefore, it is necessary to increase the size of the inductor Lo so as not to saturate the current. Further, in this case, the on-time of the switching element SW1 is independently changed for frequency modulation. Therefore, PWM control for adjusting the duty of the switching element SW1 with respect to the power supply voltage fluctuation cannot be performed. It was found that the output could not be stabilized.

In the circuit configuration shown in FIG.
As in the circuit configuration of FIG. 6A, when the oscillation frequency is lower than the reference frequency (FIG. 7C), when the on-duty of the switch element SW1 is based on the frequency (FIG.
(See (a))). As a result, the peak value of the current flowing through the switch element SW1 and the peak value of the voltage generated at the switch element SW1 are both much larger than at the time of the reference frequency. Therefore, in performing the frequency modulation, it is necessary to use a switch element SW1 having a large current rating and a large voltage rating, which increases the cost. Further, the inductor L
Since the current flowing through o increases, the size of the inductor Lo increases in order to prevent the current from saturating. Further, in the circuit configuration of FIG. 6B, a circuit for changing the input voltage to the inverter circuit for the purpose of coping with a larger voltage fluctuation of the DC power supply E and dimming the discharge lamp RL is added. , This additional circuit is connected to the second switch element SW
0 performs a switching operation. Thus, the switching of the second switch element SW0 also causes electromagnetic noise. Therefore, the effect of noise reduction is small only by the frequency modulation of the switch element SW1, and the frequency modulation operation of the second switch element SW0 is also desired.
The second switch element SW0 is PWM-controlled independently of the switch element SW1, and there is a problem that the control circuit becomes very complicated to perform the frequency modulation operation on the second switch element SW0.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a discharge lamp lighting device for performing frequency modulation, in which a simple control circuit is used to reduce electric stress on a switch element and an inductor. It is an object of the present invention to provide a discharge lamp lighting device capable of controlling power supply voltage fluctuation and controlling dimming while controlling the frequency while suppressing the increase in cost and size of components.

[0010]

In order to achieve the above object, in a discharge lamp lighting device according to the present invention, a high frequency power supply having a first switch element and comprising a one-piece voltage resonance circuit is provided. Unit, a power supply adjusting unit that adjusts an output from the DC power supply to the high-frequency power supply unit by a switching operation of a second switch element, and a load circuit including a discharge lamp supplied with high-frequency power from the high-frequency power supply unit. In the discharge lamp lighting device, the off time of the switching operation of the first switch element is constant, the on time is variable, and the second
And a control unit for setting a predetermined length of a simultaneous ON period in which the ON time of the switching operation of the switch element and the ON time of the first switch element overlap.

With this, the switching operation of the first switch element is made constant in the control section and the on-time is made variable by the control section, and the on-time of the first switch element is reduced in order to lower the frequency of the switching operation. Even if it grows up,
The simultaneous ON period in which the ON time of the first switch element and the ON time of the switching operation of the second switch element overlap each other has a predetermined length, and the magnitude of the current energy from the high-frequency power supply unit has a predetermined magnitude. The peak value of the voltage of the first switch element can be kept constant.

It is preferable that the control unit automatically adjusts the simultaneous ON period with respect to a voltage change of the DC power supply. In this case, the control section automatically adjusts the simultaneous ON period with respect to the voltage fluctuation of the DC power supply.

Preferably, the control section controls the simultaneous ON period by detecting a current flowing through the first switch element. In this case, during the simultaneous ON period, the control unit detects and controls the current supplied to the first switch element.

Further, it is preferable that the control unit controls the simultaneous ON period by detecting a voltage of the DC power supply.
In this case, the control unit detects and controls the voltage of the DC power supply during the simultaneous ON period.

It is preferable that the discharge lamp is dimmed by adjusting the value of the simultaneous ON period. In this case, the discharge lamp is dimmed and lit by adjusting the value of the simultaneous ON period.

[0016]

1 to 4 show a first embodiment of the present invention corresponding to all of claims 1 to 3 and 5, and FIG. 5 shows a second embodiment of the present invention corresponding to claim 4. Is shown.

[First Embodiment] FIG. 1 is a circuit diagram showing a schematic configuration of a discharge lamp lighting device according to a first embodiment of the present invention, and FIG. 2 shows the operation of the discharge lamp lighting device. FIG. 3 is a circuit diagram showing a schematic configuration of another embodiment of the discharge lamp lighting device, and FIG. 4 is an explanatory diagram showing an operation of the discharge lamp lighting device.

The discharge lamp lighting device 1 of this embodiment includes a high-frequency power supply unit 3 having a first switch element SW1 and configured as a one-piece voltage resonance circuit, Discharge lamp lighting comprising a power supply adjustment unit 4 for adjusting the output to the power supply by the switching operation of a second switch element SW0, and a load circuit 5 including a discharge lamp RL to which the high-frequency power from the high-frequency power supply unit 3 is supplied. In the device 1,
The off time of the switching operation of the first switch element SW1 is constant, the on time is variable, and the on time of the switching operation of the second switch element SW0 is
The control unit 2 has a predetermined length of the simultaneous ON period overlapping the ON time of the switch element.

Further, in the discharge lamp lighting device 1 of the embodiment, the control section 2 automatically adjusts the simultaneous ON period with respect to the voltage fluctuation of the DC power supply E.
Further, in the discharge lamp lighting device 1 of the embodiment, the control unit 2 controls the simultaneous ON period by detecting a current flowing through the first switch element SW1.

More specifically, this discharge lamp lighting device 1 is shown in FIG.
As shown in FIG. 1, an inverter circuit corresponding to the high-frequency power supply unit 3 is connected via a power supply adjustment unit 4 to the output side of a DC power supply E that rectifies and outputs an AC power supply via a rectifier (not shown). 6, the same reference numerals as those in FIG. 6 denote the same parts, and the basic configurations of the high-frequency power supply unit 3, the power supply adjustment unit 4, and the load circuit 5 are the same as those of the conventional one shown in FIG. Is the same as A feature of the illustrated example is that a control unit 2 is provided as shown in FIG.

The discharge lamp lighting device 1 includes a DC power source E and an inductor L in the same manner as described in the section of the prior art.
, a first switch element SW1 and a capacitor Co, a high-frequency power supply section, an inductor L1, a capacitor C
And a load circuit including a discharge circuit RL and a load circuit including a discharge lamp RL, and limiting a peak value of a current flowing through the inductor Lo between the DC power supply E and the inductor Lo. A power supply adjustment unit including the switch element SW0 and the diode D1 is provided, and a resistor r for detecting a current flowing through the first switch element SW1 is provided.

The control section 2 has a frequency modulation circuit 21, a comparator 22, and an AND circuit 23. This frequency modulation circuit 21 performs duty control to make the off time constant and the on time variable with respect to the reference frequency f of the switching oscillation frequency, and generates a frequency modulated with a certain frequency width Δf. This is for switching one switch element SW1. Note that this modulation means may be sweep modulation for gradually changing the frequency or random modulation for rapidly changing the frequency.

The comparator 22 has a predetermined value VREF voltage,
By comparing the current flowing through the first switch element SW1 detected by the resistor r with a voltage conversion value, outputting an H voltage when the current flowing through the first switch element SW1 is lower than a predetermined value VREF; , When it is high, an L voltage is output. The AND circuit 23 monitors the current flowing through the first switch element SW1 via the resistor r, and synchronizes the switching frequency of the second switch element SW0 with the switching frequency of the first switch element SW1. is there.

In this case, during the simultaneous ON period when both the first switch element SW1 and the second switch element SW0 are turned on, a current flows from the DC power supply E to the inductor Lo and is stored in the inductor Lo. Current energy increases. When the first switch element SW1 is kept on and the second switch element SW0 is turned off, the diode D1 is turned on. At this time, a current flows in a closed loop circuit including the inductor Lo, the switch element SW1, the resistor r, and the diode D1 so as to maintain the current energy stored in the inductor Lo. When the first switch element SW1 is turned off, the current energy stored in the inductor Lo is sent to the load circuit 5 via the capacitor Co and the like.

The first switch element SW1 is driven by a drive signal output from the frequency modulation circuit 21 and having a constant off time and a variable on time in the signal waveform shown in FIG. Also, the second switch element SW0
Is the frequency modulation circuit 2 via the AND circuit 23
2 is driven by a drive signal having a signal waveform shown in FIG. 2C, which is synchronized with the drive signal by No. 1 and is limited so that the current detected by the detection resistor r does not exceed a predetermined value VREF in the comparator 22. Is done. That is, only when both the output signal of the frequency modulation circuit 21 and the output signal of the comparator 22 become the H voltage by the AND circuit 23, the second
Is turned on. As a result, the current flowing through the first switch element SW1 is limited so as not to exceed a predetermined value VREF, and
Of the switching element SW1 and the second switching element S
The frequency of W0 can be synchronized.

In the discharge lamp lighting device described above, the frequency modulation circuit 21 has a constant off time and a variable on time as shown in FIG. To generate a frequency signal waveform. In this embodiment, the oscillation frequency of the drive signal is f
This shows a case in which the frequency is rapidly switched from max to the lower limit fmin.

First, the operation when the oscillation frequency is fmax will be described. In this case, the drive signal waveform to the first switch element SW1 output from the frequency modulation circuit 21 turns on at time t0, switches from on to off at time t2, and turns off until time t3, as shown in FIG. maintain. Time t
Before 0, the output of the frequency modulation circuit 21 is an L voltage, and since the first switch element SW1 is off, the current flowing through the detection resistor r is zero.
The output of the comparator 22 is the H voltage. Therefore, at time t
The output signal of the AND circuit 23 before 0 becomes an L voltage, and the second switch element SW0 is turned off.

At time t0, when the drive signal waveform to the first switch element SW1 output from the frequency modulation circuit 21 becomes H voltage, the first switch element SW1 is turned on, and at the same time, the output signal of the AND circuit 23 becomes H level. As a result, the second switch element SW0 is turned on. At this time, FIG.
As shown in (d), the first switch element S is supplied from the DC power supply E via the second switch element SW0 and the inductor Lo.
The current starts to flow through W1 and the detection resistor r and monotonically increases. Then, the supplied current is a predetermined reference voltage value V
When the current value Ip becomes equivalent to REF (time t
1) The comparator 22 outputs the L voltage, the output signal of the AND circuit 23 becomes the L voltage, and the second switch element SW0 is turned off. Then, the current from the DC power supply E is cut off, the diode D1 is turned on instead, and the current of the current value Ip continues to flow through the inductor Lo, the first switch element SW1, the detection resistor r, and the diode D1. afterwards,
When the first switch element SW1 is turned off at time t2,
The current energy stored in the inductor Lo is released to the load circuit side, and the first switch element SW1
A voltage as shown in (e) is generated. The voltage generated by the first switch element SW1 depends on the magnitude of the current energy stored in the inductor Lo, and the peak value of the voltage is Vp when the current is Ip.

Next, the operation when the oscillation frequency is fmin will be described. In this case, as shown in FIG. 2, the drive signal waveform output from the frequency modulation circuit 21 to the first switch element SW1 turns on at time t3, switches from on to off at time t5, and turns off until time t6. maintain. In this case, as in the case where the oscillation frequency is fmax, when the drive signal waveform to the first switch element SW1 output from the frequency modulation circuit 21 at time t3 becomes the H voltage, the first
Switch element SW1 is turned on, and the AND circuit 23
Output signal of the second switch element SW0
Is also turned on. At this time, as shown in FIG. 2D, the DC power source E switches the second switch element SW0 and the inductor L
o, the first switch element SW1 and the detection resistor r
The current starts to flow and monotonically increases. Then, when the supplied current reaches a current value Ip corresponding to a predetermined reference voltage value VREF (time t4), the comparator 22 outputs the L voltage, and the output signal of the AND circuit 23 becomes the L voltage, The second switch element SW0 is turned off. Then, the current from the DC power supply E is cut off, the diode D1 is turned on instead, and the current of the current value Ip continues to flow through the inductor Lo, the first switch element SW1, the detection resistor r, and the diode D1.

Thereafter, at time t5, the first switch element S
When W1 is turned off, the current energy accumulated in the inductor Lo is released to the load circuit side, and the first switch element SW1 has the same peak value as the voltage of Vp as shown in FIG. Occurs. That is, in order to lower the frequency of the switching operation, the first switch element S
Even if the on-time of W1 increases, the magnitude of the current energy stored in the inductor Lo is maintained at the predetermined current value Ip, so that the peak value of the voltage of the first switch element SW1 is set to the same value as at fmax. Vp can be kept constant.

At this time, even when the voltage of the DC power supply E fluctuates, the ON time T of the second switch element SW0 is automatically changed, and the magnitude of the current energy stored in the inductor Lo is fixed at a predetermined current value Ip. Is maintained. Further, in this configuration, the first switch element SW1
And the frequency of the second switch element SW0 coincide with each other and change, so that only one frequency modulation circuit 21 can modulate the two switch elements SW1 and SW0. Therefore, noise can be easily reduced and the control circuit for modulation does not become complicated. In the above configuration,
For example, by reducing the value of the predetermined reference voltage value VREF, the value of the simultaneous ON period can be adjusted.
As a result, the current energy stored in the inductor Lo can be reduced, and the power applied to the discharge lamp RL may be reduced to make the discharge lamp RL dimly lit. In this way, the discharge lamp RL can be easily dimmed and lit, and noise reduction during dimming can be realized.

In the above configuration, the reference frequency f = 30 k
When the frequency modulation operation with a modulation width of Δf ± 10 kHz at Hz is performed, the electromagnetic noise can be reduced by about 10 dB as compared with the case described in the section of the related art, and the first switch element SW1 is a conventional switch. In the state described in the section of technology, the voltage and current rating must be 1.5 times,
The inductor Lo had to be double in volume, but according to the above configuration, the reference frequency f = 30 kHz
Even if a frequency modulation operation with a modulation width of Δf and a frequency of 10 kHz is performed at z, the electrical stress on the first switch element SW1 does not change. Therefore, it has been found that both the first switch element SW1 and the inductor Lo may be the same as those designed at the reference frequency f = 30 kHz, and that the electromagnetic noise can be reduced by about 10 dB. Further, the voltage fluctuation of the DC power supply E can cope with a fluctuation of 50%, and at this time, it was confirmed that the noise reduction effect was also about 10 dB.

Therefore, according to the discharge lamp lighting device described above, the switching operation of the first switch element SW1 is made constant in the off time and the on time is made variable in the control section 2, thereby lowering the frequency of the switching operation. Therefore, even if the ON time of the first switch element SW1 increases,
The simultaneous ON period in which the ON time of the first switch element SW1 and the ON time of the switching operation of the second switch element SW0 overlap is set to a predetermined length, and the magnitude of the current energy from the inverter circuit serving as the high-frequency power supply unit Is maintained at a predetermined value, and the peak value of the voltage of the first switch element SW1 can be kept constant. Therefore, even if the frequency modulation is performed, the current rating and the voltage rating of the first switch element SW1 are both increased. This eliminates the need for change, and therefore, with a simple control circuit, electrical stress on the switch elements SW1 and SW0 and the inductor Lo can be suppressed, and there is no increase in cost and size of components. Furthermore, it is possible to cope with fluctuations in power supply voltage, and to realize dimming control by frequency modulation.

The control section 2 automatically adjusts the simultaneous ON period with respect to the voltage fluctuation of the DC power supply E, so that the output does not change and there is no increase in stress due to frequency modulation. Further, since the control unit 2 detects and controls the voltage of the DC power supply E during the simultaneous ON period, the control circuit can be configured more easily. Further, since the discharge lamp RL is dimmed by adjusting the value of the simultaneous ON period, dimming control can be realized by frequency modulation, and the dimming circuit can be configured more easily.

In the present invention, in addition to the above-described inverter circuit in which the inductor Lo is formed by an inductor coil, for example, a transformer having an inductor may be used. The effect of the electromagnetic noise reduction of the present invention is the effect of the inductor L1 and the capacitors C and C2.
Needless to say, it does not depend on the configuration of the filter circuit unit consisting of, of course, the presence or absence of a filter circuit, or
It is needless to say that the present invention is not limited by the combination but includes various embodiments such as the configuration according to the embodiment shown in FIG.

Specifically, in the embodiment shown in FIG. 3, the AND circuit 23 of the above embodiment is omitted, and the second switch element SW0 is directly driven by the output signal of the comparator 22. FIG. 4 shows operation waveforms of this configuration.

The difference from FIG. 1 is that the duty of the second switch element SW0, that is, the ratio of the ON time and the OFF time is changed. In the operation of FIG. 1, the second switch element SW0 is always off when the first switch element SW1 is off.
In this case, the second switch element SW0 is always on when the first switch element SW1 is off. Then, even when the second switch element SW0 is on when the first switch element SW1 is off, the drive is performed such that the magnitude of the current energy stored in the inductor Lo is kept constant at the predetermined current value Ip. It is about to be. As a result, the peak value of the voltage of the first switch element SW1 is also changed as shown in FIG.
Vp can be kept constant as shown in FIG.

In the case of the configuration shown in FIG. 3, the switching phase of the first switch element SW1 and the switching phase of the second switch element SW0 are shifted, but the frequency modulation is performed on both the first switch element SW1 and the second switch element SW0. 1 and has the same effect as that shown in FIG. With this configuration, the control circuit can be further simplified in that the above-described AND circuit 23 can be omitted.

[Second Embodiment] FIG. 5 is a circuit diagram showing a schematic configuration of a discharge lamp lighting device according to a second embodiment.

In the discharge lamp lighting device 1 of this embodiment, the control section 2 detects the voltage of the DC power supply E and controls the simultaneous ON period.

More specifically, as shown in FIG. 5, the discharge lamp lighting device 1 eliminates the comparator 22 and the detection resistor r from the configuration of the other embodiment shown in FIG. 3 of the first embodiment. And
It becomes the control unit 2. An input voltage detection circuit 6 for detecting an input voltage from the DC power supply E, and a second switch element SW corresponding to the input voltage based on an output from the input voltage detection circuit 6
A switching time setting circuit 7 for setting an ON time width T of a switching operation of 0, and an ON signal of the first switching element SW1 which receives the output signal of the frequency modulation circuit 21 and changes the ON time to the switching time. It is provided with a switch drive circuit 8 that changes the ON time width T from the setting circuit 7 and drives the second switch element SW0.

In the case of this configuration, the control unit 2 having the above configuration
Are to make the off time of the switching operation of the first switch element SW1 constant, to make the on time variable, and to set the on time of the switching operation of the second switch element SW0 to the first time.
The ON time of the second switch element SW0 is maintained at T in the same manner as the operation waveform shown in FIG. Therefore, the driving is performed so that the magnitude of the current energy stored in the inductor Lo is kept constant at the predetermined current value lp, and the peak value of the voltage of the first switch element SW1 can also be kept constant at Vp.

Also in this configuration, the frequency of the first switch element SW1 and the frequency of the second switch element SW0 coincide with each other and change, so that only one of the frequency modulation circuits 21 switches the two switch elements SW1 and SW0. Is possible, noise is easily reduced, and a control circuit for the modulation is not complicated. In addition, for the power supply voltage fluctuation of the DC power supply E, the switching time setting circuit 7 sets the ON time T of the switching operation of the second switch element SW0 according to the power supply voltage of the DC power supply E, and T when the power supply voltage is high. And when the power supply voltage is low, T is increased so that the magnitude of the current energy stored in the inductor Lo can be maintained at a predetermined current value Ip.
In addition, there is no increase in electrical stress on the switching elements SW1 and SW0 and the inductor Lo due to frequency modulation.

Therefore, according to the discharge lamp lighting device 1,
Since the control unit 2 detects and controls the voltage of the DC power supply E during the simultaneous ON period, the detection resistor r for detecting the current of the switch element SW1 can be omitted, and the efficiency can be improved without power loss due to the detection resistor r. .

[0045]

The present invention is embodied as in the above-mentioned embodiment. In the discharge lamp lighting device according to the first aspect, the switching operation of the first switch element by the control unit reduces the off time. Even if the ON time is made constant and the ON time of the first switch element is increased to lower the frequency of the switching operation, the ON time of the first switch element and the switching operation of the second switch element are reduced. Is set to a predetermined length, the magnitude of the current energy from the high-frequency power supply unit is maintained at a predetermined level, and the peak value of the voltage of the first switch element can be made constant. In a discharge lamp lighting device that performs frequency modulation, it is possible to suppress electrical stress on the switch element and the inductor with a simple control circuit, and to increase the cost and size of parts. The power supply voltage variation response and dimming or the like can be controlled with frequency modulation to suppress the Rukoto.

Further, in the discharge lamp lighting device according to the second aspect, since the control unit automatically adjusts the simultaneous ON period with respect to the voltage fluctuation of the DC power supply, the output does not change. Also, there is no increase in stress due to frequency modulation.

In the discharge lamp lighting device according to the third aspect, since the control unit detects and controls the current supplied to the first switch element during the simultaneous ON period, the control circuit can be simplified. Can be configured.

Further, in the discharge lamp lighting device according to the fourth aspect, since the control unit detects and controls the voltage of the DC power supply during the simultaneous ON period, the detection resistor for detecting the current of the switch element is used. The efficiency can be improved without any power loss due to the detection resistor.

Further, in the discharge lamp lighting device according to the fifth aspect, since the discharge lamp is dimmed by adjusting the value of the simultaneous ON period, dimming control is realized by frequency modulation. As a result, the dimming circuit can be configured more easily.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a schematic configuration of a discharge lamp lighting device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an operation of the discharge lamp lighting device.

FIG. 3 is a circuit diagram showing a schematic configuration of another embodiment of the discharge lamp lighting device.

FIG. 4 is an explanatory diagram showing an operation of the discharge lamp lighting device.

FIG. 5 is a circuit diagram illustrating a schematic configuration of a discharge lamp lighting device according to a second embodiment.

FIG. 6 is an explanatory diagram showing a schematic configuration of a discharge lamp lighting device as a conventional example of the present invention.

FIG. 7 is an explanatory diagram showing an operation of the discharge lamp lighting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Discharge lamp lighting device 2 Control part 3 High frequency power supply part 4 Power supply adjustment part 5 Load circuit SW1 1st switch element SW0 2nd switch element E DC power supply RL Discharge lamp

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H05B 41/392 H05B 41/29 CF term (Reference) 3K072 AC12 BA03 BC01 CA16 CB04 CB08 FA04 GB04 GC04 HA09 HA10 HB03 3K098 CC05 CC12 CC41 CC52 CC57 DD22 DD43 DD44 DD46 EE08 EE14 EE32 EE40 FF12 FF20 5H007 AA01 AA06 BB03 CA00 CB23 DA03 DA05 DC02

Claims (5)

[Claims] 1. A high-frequency power supply including a first switch element and configured as a single-pole voltage resonance circuit, and an output from a DC power supply to the high-frequency power supply is adjusted by a switching operation of a second switch element. And a load circuit including a discharge lamp to which high-frequency power is supplied from the high-frequency power supply unit, wherein the off-time of the switching operation of the first switch element is constant and on. A discharge lamp provided with a control unit that makes a time variable and sets a predetermined length of a simultaneous ON period in which an ON time of a switching operation of the second switch element and an ON time of the first switch element overlap. Lighting device. 2. The controller according to claim 1, wherein the controller automatically adjusts the simultaneous ON period with respect to a voltage change of the DC power supply.
The discharge lamp lighting device as described in the above. 3. The discharge lamp lighting device according to claim 1, wherein the control unit controls the simultaneous ON period by detecting a current flowing through the first switch element. 4. The discharge lamp lighting device according to claim 1, wherein the control unit controls the simultaneous ON period by detecting a voltage of the DC power supply. 5. The discharge lamp lighting device according to claim 1, wherein the discharge lamp is dimly lit by adjusting the value of the simultaneous ON period.