JP2003100489A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device with improved voltage conversion efficiency when controlling the light by adjusting a direct current voltage. SOLUTION: A direct current power source part 1 comprises a step-up chopper circuit 10, a step-up/down chopper circuit 11, and a switching means 12. A control circuit 4 switches the operation of the direct current power source part 1 into a step-up operation by connecting the input of the direct current power source part 1 to the step-up chopper circuit 10 by the switching means 12 when the direct current voltage Vdc between both ends of a capacitor C1 exceeds a prescribed voltage, and switches the operation of the direct current power source part 1 into a step-up/down operation by connecting the input of the direct current power source part 1 to the step-up/down chopper circuit 11 by the switching means 12 when the direct current voltage Vdc between both ends of a capacitor C1 becomes less than the prescribed voltage, by the above, the voltage conversion efficiency is improved.

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 A discharge lamp lighting device of Conventional Example 1 whose circuit diagram is shown in FIG. 18 supplies a high frequency voltage obtained by converting an output voltage of a DC power supply unit 101 by an inverter unit 100 to a discharge lamp La. 100 is a series circuit of switching elements Q100 and Q101 connected in parallel to the DC power supply unit 101, a capacitor C100 having one end connected to the connection midpoint of the switching elements Q100 and Q101, and switching elements Q100 and Q101 turned on. The load circuit, which is composed of a control circuit 100a that is turned off and the inverter unit 100 supplies a high frequency voltage, is a switching element Q1.
01 is connected in parallel via a capacitor C100 to an inductor L101, a series circuit of a capacitor C101, and a discharge lamp La connected in parallel to the capacitor C101. A lamp voltage Vla is applied to the discharge lamp La.
The lamp current Ila flows. Then, the DC power supply unit 101
Dimming is performed by adjusting the DC voltage Vdc output by the different load, and even if discharge lamps La with different rated powers are mounted, the light output ratio between different discharge lamps can be controlled to be approximately constant It is a discharge lamp lighting device.

Next, in the discharge lamp lighting device of the second conventional example shown in FIG. 19, the DC power supply unit 101 is composed of a step-up chopper circuit. The DC power supply unit 101 outputs the AC power supply Vs and the output of the AC power supply Vs. Diode bridge DB for rectifying
A series circuit of an inductor L102 and a diode D100 connected to the positive output side of the diode bridge DB, a switching element Q102 connected in parallel to the output end of the diode bridge DB via the inductor L102, and a switching element via the diode D100. A smoothing capacitor C102 connected in parallel with Q102, a dimmer 101a for setting a dimming level, and a switching element Q102 turned on according to a dimming signal from the dimmer 101a.
The control circuit 101b is turned off to control the DC voltage Vdc output from the DC power supply unit 101.

In the discharge lamp lighting device of Conventional Example 2,
The range of the DC voltage Vdc output by the DC power supply unit 101 is
Vs (peak) ≦ Vdc (where Vs (peak)
Indicates the peak voltage of the AC power supply Vs). For example,
If the AC power supply Vs is an AC power supply of 100V, the peak voltage Vs (peak) is 141V, and if the AC power supply is 200V, the peak voltage Vs (peak) is 282V.

Therefore, the dimming lower limit, which is predetermined by the dimmer, is set to the peak voltage Vs (pea) of the AC power source Vs.
If the value of (k) is set, that is, if it is set to the dimming lower limit when the DC voltage Vdc = 141V in the case of an AC power source of 100V, the DC voltage Vdc will not drop below that value. , The control circuit 101b has a DC voltage Vdc
Does not require a limiter circuit for limiting the value so as not to fall below a predetermined level, and control is facilitated.

In the conventional example 2 as described above, even when the discharge lamps La having different rated powers are mounted, the inverter unit 10
The light output ratio between the discharge lamps having different rated powers can be controlled to be substantially constant by adjusting the DC voltage Vdc while keeping the lighting frequency of 0 constant, and the value of the DC voltage Vdc at the lower limit of the light control Since it is not necessary to control the control circuit, the control circuit can be easily configured, and further, since the DC power supply unit 101 configures the boost chopper circuit, there is an advantage that the voltage conversion efficiency in the chopper circuit is high.

Next, in the discharge lamp lighting device of Conventional Example 3 shown in FIG. 20, the DC power supply unit 101 is composed of a step-up / down chopper circuit. The DC power supply unit 101 includes an AC power supply Vs and an AC power supply Vs. Diode bridge DB that rectifies the output
And a series circuit of a switching element Q103 and a diode D100 connected to the negative output side of the diode bridge DB, and an inductor L1 connected in parallel to the output terminal of the diode bridge DB via the switching element Q103.
02 and the inductor L10 via the diode D100.
2, a condenser C102 for smoothing connected in parallel, a dimmer 101a for setting a dimming level, and a dimmer 101a
DC voltage Vd output from the DC power supply unit 101 by turning on / off the switching element Q103 according to the dimming signal from
and a control circuit 101b for controlling c.

In the discharge lamp lighting device of Conventional Example 3,
The range of the DC voltage Vdc output by the DC power supply unit 101 is
It can be arbitrarily set regardless of the peak voltage Vs (peak) of the AC power supply Vs. That is, the DC voltage Vd
When c requires a voltage lower than the peak voltage Vs (peak) of the AC power supply Vs, the step-up / down chopper circuit of the DC power supply unit 101 is stepped down so that the DC voltage Vdc is the peak voltage Vs.
When a voltage higher than s (peak) is required, the step-up / step-down chopper circuit of the DC power supply unit 101 may be boosted.
Therefore, the limitation of the DC voltage Vdc by the AC power supply Vs is removed, and the control range of the lamp current Ila of the discharge lamp La is expanded.

In the conventional example 3 as described above, even when the discharge lamps La having different rated powers are mounted, the inverter unit 10
The light output ratio between the discharge lamps having different rated powers can be controlled to be substantially constant by adjusting the DC voltage Vdc while keeping the lighting frequency of 0 constant, and since the lighting frequency is constant, the control circuit is Since the control range of the DC voltage Vdc output from the DC power supply unit 101 is not limited by the AC power supply Vs, it can be controlled to an arbitrary lamp current Ila, and the control range is widened. be able to.

Further, in the discharge lamp lighting device of Conventional Example 4 shown in FIG. 21, the DC power supply unit 101 is composed of a two-stone step-up / down chopper circuit.
s, a diode bridge DB that rectifies the output of the AC power supply Vs, a series circuit of an inductor L102, a diode D100, a switching element Q104, and an inductor L103 connected to the positive output side of the diode bridge DB, and an inductor L102. Diode bridge D
Switching element Q102 connected in parallel to the output terminal of B
And the switching element Q1 via the diode D100.
02, a smoothing capacitor C102 connected in parallel,
Capacitor C102 via switching element Q104
Diode D101 connected in parallel with the inductor L
A capacitor C103 connected in parallel to a diode D101 via 103 and a dimmer 10 for setting a dimming level.
1a and the switching element Q104 is turned on / off according to a dimming signal from the dimmer 101a to control the DC power supply unit 1
Control circuit 10 for controlling the DC voltage Vdc output by 01
1b, and a control circuit 101c for on / off controlling the switching element Q102.

[0011]

However, in the above-mentioned conventional example, when the configuration of the DC power supply unit 101 is the step-up chopper circuit shown in FIG. 19, the DC voltage Vdc is changed to the AC power supply V
Since it cannot be set to the peak voltage Vs (peak) of s or less, control cannot be performed in a wide range, and deeper dimming cannot be performed.

Further, when the configuration of the DC power supply unit 101 is the step-up / step-down chopper circuit shown in FIG. 20, the cost is high because a high breakdown voltage switching element must be used, and the voltage conversion is higher than that of the step-up chopper circuit. Will be less efficient. Further, when the two-stone type buck-boost chopper circuit shown in FIG. 21 is used, the number of elements is increased as compared with the case of using the one-stone type chopper circuit, so that there is a drawback that the loss in the chopper circuit is increased.

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 in which the efficiency of voltage conversion when adjusting the DC voltage to perform dimming is improved. is there.

[0014]

According to a first aspect of the present invention, there is provided a diode bridge for converting a voltage of an AC power supply into a DC voltage, and a switching element. The diode bridge is formed by turning on / off the switching element. A DC power supply unit that converts the output DC voltage to a desired voltage, a capacitor that smoothes the output of the DC power supply unit, an inverter unit that converts the voltage of the capacitor into a high frequency voltage, and a high frequency voltage output by the inverter unit. A discharge lamp, a control circuit for controlling the on / off operation of the switching element of the DC power supply unit, and the operation of the DC power supply unit when the voltage of the capacitor is equal to or higher than a predetermined voltage. Switching to operation, switching the operation of the DC power supply section to the operation of the buck-boost chopper circuit when the voltage of the capacitor is below a predetermined voltage. Characterized in that it comprises a switching means.

According to a second aspect of the present invention, in the first aspect of the present invention, the switching means always causes the operation of the DC power supply unit to be the operation of the step-up / down chopper circuit when the voltage of the AC power supply is equal to or higher than a predetermined voltage. It is characterized by switching.

According to a third aspect of the present invention, in the first or second aspect of the invention, the voltage of the AC power source is set to about 100V, and the switching means operates the DC power source unit so that the voltage of the capacitor is about 200V or more. At the time of, the operation is switched to the operation of the boost chopper circuit, and when the voltage of the capacitor is approximately 200 V or less, the operation is switched to the operation of the buck-boost chopper circuit.

According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the voltage of the capacitor when the switching means switches the operation of the DC power supply section to the operation of the step-up chopper circuit or the step-up / step-down chopper circuit, It is characterized in that the total harmonic distortion rate of the output current of the AC power supply is set to be a predetermined value or less.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the switching means controls the ON / OFF timing of the switching element of the DC power source section by the control circuit. It is characterized in that the operation of the DC power supply unit is switched to the operation of the step-up chopper circuit or the step-up / step-down chopper circuit.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, the DC power supply unit includes two or more switching elements, and the two or more switching elements have a common ground level. It is characterized by

According to a seventh aspect of the present invention, in the fifth or sixth aspect of the invention, the DC power supply unit includes two or more switching elements, and the control circuit controls the on / off timing of one switching element. By doing so, the operation of the DC power supply unit is switched to the operation of the step-up chopper circuit or the step-up / step-down chopper circuit.

According to an eighth aspect of the present invention, in the seventh aspect, the DC power supply unit includes two switching elements, and the control circuit includes a comparator that compares a voltage of the capacitor with a reference voltage, and the comparator. It is provided with two drive circuits having mutually different drive signals for turning on / off the switching element, and a switch for switching the drive circuit of one of the switching elements to one of the two drive circuits according to the comparison result of the comparator. The other switching element is always turned on / off by one of the two driving circuits.

According to a ninth aspect of the present invention, in the invention according to any one of the first to eighth aspects, the switching means switches the operation of the DC power supply unit to the operation of the step-up chopper circuit or the step-up / step-down chopper circuit. And a step-up / step-down chopper circuit, a period for alternately performing the step-up chopper circuit and the step-up / step-down chopper circuit is provided.

According to a tenth aspect of the present invention, in any one of the fifth to eighth aspects, when the discharge lamp is supplied with a constant electric power, the control circuit controls the operation of the DC power supply unit to operate the step-up chopper circuit. The ratio of the ON time of the switching element at the time of the above to the ON time of the switching element at the time of operating the DC power supply unit as the operation of the step-up / down chopper circuit is made constant.

According to an eleventh aspect of the present invention, in the invention of the tenth aspect, the ON time of the switching element when the operation of the DC power supply unit is the operation of the step-up chopper circuit is the same as the operation of the DC power supply unit. It is characterized in that it is 1 / √2 times the ON time of the switching element when operating the circuit.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows a block configuration of this embodiment, which has an AC power supply Vs, a diode bridge DB for rectifying the output of the AC power supply Vs, and a switching element, and turns on the switching element. The DC power supply unit 1 that converts the DC voltage output from the diode bridge DB into a desired DC voltage Vdc by turning it off, the electrolytic capacitor C1 that smoothes the output of the DC power supply unit 1, and the DC voltage Vdc across the capacitor C1. The inverter unit 2 for converting into a high frequency voltage, the discharge lamp La supplied with the high frequency voltage output from the inverter unit 2, the dimmer 3 for setting the dimming level, the DC voltage Vdc across the capacitor C1 and the dimmer. The control circuit 4 controls ON / OFF of the switching element of the DC power supply unit 1 according to the dimming signal 3.

Here, the DC power supply unit 1 includes a step-up chopper circuit 10, a step-up / step-down chopper circuit 11, and a switching means 12.
When the DC voltage Vdc across the capacitor C1 is equal to or higher than a predetermined voltage, the control circuit 4 has a switching means 12
The input of the DC power supply unit 1 is connected to the step-up chopper circuit 10 to switch the operation of the DC power supply unit 1 to the boosting operation, and when the DC voltage Vdc across the capacitor C1 is equal to or lower than a predetermined voltage, the switching unit 12 causes the DC power supply unit to operate. The input of 1 is connected to the buck-boost chopper circuit 11 to switch the operation of the DC power supply unit 1 to the buck-boost operation.

Next, FIG. 2 shows a specific circuit configuration of this embodiment. The DC power supply unit 1 is connected in parallel to the output terminal of the diode bridge DB via the switching element Q1, a series circuit of an inductor L1 and a diode D2 connected to the positive output side of the diode bridge DB, and a switching element Q1. Diode D1 and F connected in parallel to diode D1 via inductor L1
2 composed of a switching element Q2 composed of ET
It is a stone type buck-boost chopper circuit. The inverter unit 2 is
A series circuit of switching elements Q3 and Q4 connected in parallel to a capacitor C1 connected to the output terminal of the DC power supply unit 1, a series circuit of a capacitor C2, an inductor L2 and a capacitor C3 connected in parallel to the switching element Q4,
The discharge lamp La is connected in parallel to the capacitor C3, which is a half-bridge inverter composed of a control circuit 2a for alternately driving the switching elements Q3 and Q4 on and off. The control circuit 4 detects the DC voltage Vdc across the capacitor C1 via the input terminal c and drives the switching elements Q1 and Q2 via the output terminals a and b, respectively.

Next, the control method by the control circuit 4 will be described. 3A, 3B, and 3C show (a) a gate signal Vq1 of the switching element Q1, (b) a gate signal Vq2 of the switching element Q2, and (c) a capacitor C1.
Each waveform of the DC voltage Vdc at both ends is shown, and the horizontal axis shows the dimming state, that is, the left side shows the full lighting state (Full state) and the right side shows the dimming lower limit state (Dim state). When the DC voltage Vdc is equal to or higher than the threshold voltage V1 (when the dimming state is closer to the Full state than the point p), the gate signal Vq1 is H.
The switching element Q1 maintains the ON state while maintaining the high level, the gate signal Vq2 is repeatedly turned on and off at a high frequency, and only the switching element Q2 turns on and off, whereby the DC power supply unit 1 operates as a step-up chopper circuit. To do. When the DC voltage Vdc is equal to or lower than the threshold voltage V1 (when the dimming state is on the Dim state side from the point p), both the gate signals Vq1 and Vq2 are the same signal and repeatedly turned on and off at a high frequency to switch the switching element Q1. Similarly, when Q2 is turned on / off, the DC power supply unit 1 operates as a step-up / down chopper circuit. As described above, when the DC voltage Vdc across the capacitor C1 is equal to or higher than the predetermined voltage, the DC power supply unit 1 is operated as a boost chopper circuit, and when the DC voltage Vdc across the capacitor C1 is equal to or lower than the predetermined voltage, By operating the DC power supply unit 1 as a step-up / step-down chopper circuit, the loss due to high frequency switching disappears in the switching element Q1 during the period of operation as a step-up chopper circuit, and only loss due to ON resistance occurs. The efficiency of is substantially equal to that of the step-up chopper circuit, and the efficiency at the time of voltage conversion can be improved as compared with the case of operating only as the step-up / step-down chopper circuit in the entire dimming range.

FIG. 4 shows a circuit diagram of the control circuit 4.
The control circuit 4 has a comparator CP1 in which an input terminal c is connected to an inverting input terminal and a reference voltage source E1 is connected to a non-inverting input terminal, a drive circuit 4a for outputting a drive signal which is turned on / off at a high frequency, and a High circuit which is always High. And a switch 4c for switching the drive circuit connected to the output terminal a to the drive circuit 4a or the drive circuit 4b according to the output of the comparator CP1.
The output terminal b is connected to the drive circuit 4a. The voltage of the reference voltage source E1 corresponds to the threshold voltage V1 shown in FIG. 3, and when the DC voltage Vdc across the capacitor C1 input via the input terminal c is equal to or higher than the voltage of the reference voltage source E1, ( (From Vfull to V1 in FIG. 3), the output of the comparator CP1 becomes Low level, the switch 4c connects the output terminal a and the drive circuit 4b, and the drive signal of High level of the drive circuit 4b is connected to the output terminal a. Is output,
A drive signal that turns on / off the drive circuit 4a at a high frequency is output to the output terminal b, and the DC power supply unit 1 operates as a boost chopper circuit. When the DC voltage Vdc across the capacitor C1 is equal to or lower than the voltage of the reference voltage source E1 (state from V1 to Vdim in FIG. 3), the output of the comparator CP1 becomes High level, and the switch 4c outputs the output terminal a and the drive circuit. 4a is connected, and a drive signal for turning on / off at a high frequency of the drive circuit 4a is output to both output terminals a and b,
The DC power supply unit 1 operates as a buck-boost chopper circuit. Gate signals V of the switching elements Q1 and Q2 at this time
q1 and Vq2 have respective waveforms shown in FIGS. 3 (a) and 3 (b).

The present embodiment as described above is effective when the power supply voltage of the AC power supply Vs is relatively low, for example, about 100V. This is because the range in which the DC power supply unit 1 is operated as a boost chopper circuit is wider than that in the case where the power supply voltage is low, and the voltage conversion is performed more as a boost chopper circuit than as a buck-boost chopper. This is because the time efficiency is good, and the range in which the efficiency is improved is wider than that of the buck-boost chopper circuit, which is advantageous in terms of efficiency. Then, the threshold voltage V1 at this time is set to about 200V.
If set to, the efficiency can be further improved. Further, since the switching means between the step-up chopper circuit and the step-up / step-down chopper circuit is constituted by the on / off operation of the switching element Q1 which constitutes the chopper circuit of the DC power supply unit 1, the structure of the control circuit 4 is simplified. You can

(Embodiment 2) FIG. 5 shows a specific circuit configuration of this embodiment, which is different from FIG. 2 showing Embodiment 1 in that the output voltage of the diode bridge DB is input to the control circuit 4.
The difference is that the switching of the chopper circuit operation of the DC power supply unit 1 described in the first embodiment is enabled or disabled according to the output voltage of the diode bridge DB, and the other points are the same. The same reference numerals are given and the description is omitted. If the output voltage of the diode bridge DB is equal to or higher than a predetermined voltage, the control circuit 4 of the present embodiment uses the DC voltage V.
Regardless of the value of dc, the switching elements Q1 and Q2 are driven by the same gate signal that turns on and off at a high frequency, the DC power supply unit 1 operates as a buck-boost chopper circuit, and
If the output voltage of the diode bridge DB is equal to or lower than a predetermined voltage, the operation as the buck-boost chopper circuit and the operation as the boost chopper circuit are switched according to the DC voltage Vdc, as in the first embodiment.

For example, FIGS. 6 (a), 6 (b) and 6 (c)
When the power supply voltage of the AC power supply Vs is relatively high (for example, approximately 2
00V) (a) Gate signal V of switching element Q1
q1, (b) Gate signal Vq of switching element Q2
2, (c) each waveform of the DC voltage Vdc across the capacitor C1 is shown. The horizontal axis is the dimming state, that is, the left side is the full lighting state (Full state), and the right side is the dimming lower limit state (Dim state). Shows. At this time, since the power supply voltage of the AC power supply Vs is high and the output voltage of the diode bridge DB is equal to or higher than a predetermined voltage, the switching elements Q1 and Q2 are
Always receives the same gate signal that turns on and off at high frequency and operates as a buck-boost chopper circuit.

As described above, when the output voltage of the diode bridge DB, that is, the power supply voltage of the AC power supply Vs is equal to or higher than the predetermined voltage, the DC power supply unit 1 operates only as a step-up / down chopper circuit, and the power supply voltage of the AC power supply Vs is predetermined. If the voltage is equal to or lower than the voltage, the DC power supply unit 1 switches between the operation as the step-up / down chopper circuit and the operation as the step-up chopper circuit according to the DC voltage Vdc, for example, from 100V to 242V.
It is possible to deal with the AC power supply Vs having a wide range of power supply voltage. Especially when the power supply voltage is high (for example, approximately 242)
Also in V), dimming can be performed by adjusting the DC voltage Vdc.

(Third Embodiment) FIG. 7 shows a specific circuit configuration of the present embodiment. The configuration of the DC power supply unit 1 is different from that of FIG. 2 showing the first embodiment, and other points are the same. The same configurations are denoted by the same reference numerals and the description thereof will be omitted. The DC power supply unit 1 of this embodiment includes a series circuit of an inductor L1 and a diode D2 connected to the positive output side of the diode bridge DB, and a switching element Q5 composed of an FET connected to the negative output side of the diode bridge DB. , A switching element Q2 formed of an FET connected in parallel to the output terminal of the diode bridge DB via the inductor L1, and a diode D3 connected between the negative side of the smoothing capacitor C1 and the positive output side of the diode bridge DB. Is a two-stone type step-up / step-down chopper circuit constituted by and the sources of the switching elements Q2 and Q5 are connected to the same potential.

Next, a control method by the control circuit 4 of this embodiment will be described. 8 (a), (b), (c)
Is (a) the gate signal Vq5 of the switching element Q5.
(B) Gate signal Vq2 of switching element Q2
(C) Each waveform of the DC voltage Vdc across the capacitor C1 is shown. The horizontal axis shows the dimming state, that is, the left side is the full lighting state (Full state), and the right side is the dimming lower limit state (Dim state).
It is shown as. DC voltage Vdc is threshold voltage V1
In the above cases (when the dimming state is closer to the Full state than point p),
The gate signal Vq5 maintains a high level and the switching element Q5 maintains an on state, and the gate signal Vq2 repeatedly turns on and off at a high frequency to switch the switching element Q2.
The DC power supply unit 1 operates as a step-up chopper circuit by turning on and off only one. When the DC voltage Vdc is equal to or lower than the threshold voltage V1 (when the dimming state is on the Dim state side from the point p), the gate signal Vq5 maintains the Low level, the switching element Q5 maintains the OFF state, and the gate signal Vq2 is repeatedly turned on and off at a high frequency and only the switching element Q2 is turned on and off, whereby the DC power supply unit 1 operates as a step-up / down chopper circuit.

The operation of the circuit shown in FIG. 7 at this time will be described. First, when the switching element Q5 is on and the switching element Q2 is on when the DC power supply unit 1 is in the step-up chopper operation, the AC power supply Vs → diode bridge DB → inductor L1 → switching element Q2.
→ Diode bridge DB → Current flows through the path of AC power supply Vs, and energy is accumulated in the inductor L1. The switching element Q5 is turned on and the switching element Q2 is turned on.
When turned off, the energy stored in the inductor L1 becomes inductor L1 → diode D2 → capacitor C1.
→ Switching element Q5 → diode bridge DB → inductor L1 charges the capacitor C1.

Next, when the switching element Q5 is off and the switching element Q2 is on while the DC power supply unit 1 is in the buck-boost chopper operation, the AC power supply Vs → diode bridge DB → inductor L1 → switching element Q2 → diode bridge. A current flows through the path of DB → AC power supply Vs, and energy is accumulated in the inductor L1.
When the switching element Q5 is turned off and the switching element Q2 is turned off, the energy stored in the inductor L1 charges the capacitor C1 along the route of the inductor L1 → diode D2 → capacitor C1 → diode D3 → inductor L1.

Further, since the source potentials of the switching elements Q2 and Q5 are common, if the source potential is set to the ground level, for example, the gate signal V in the control circuit 4 is generated.
It becomes easy to generate q2 and Vq5. The driving method of the switching elements Q3, Q4 of the inverter unit 2 by the inverter control circuit 2a at this time may be, for example, self-excited driving using the inductor L2.

Furthermore, another circuit configuration of this embodiment is shown in FIG.
Shown in. This circuit is based on a boost chopper circuit that also serves as one stone, and is switched to a step-up / down chopper circuit by turning on / off the switching element Q5. That is, in the circuit shown in FIG. 7, the switching elements Q2 and Q4 are also used as the switching element Q4, and the diode D2 is also used as a feedback diode (not shown) of the switching element Q3. The control method by the control circuit 4 of the circuit shown in FIG. 9 is substantially the same as that of the circuit shown in FIG. 7. In FIG. 8, (a) shows the waveform of the base signal of the switching element Q5 and (b) shows the switching element Q4. The waveform of the base signal of is shown. With such a configuration, the number of switching elements can be reduced.

In the first to third embodiments, the operation of the chopper circuit is controlled by the DC voltage Vdc across the capacitor C1.
The main purpose of switching between the operation as the step-up chopper circuit and the operation as the step-up / step-down chopper circuit according to the value of is the improvement of efficiency, and the operating point of the switching is the operation that meets the purpose of improving the efficiency. The points were set. However, as its operating point, for example, the operation of the chopper circuit is switched so that the input current distortion satisfies the class C, or a predetermined total harmonic distortion rate (THD: Total).
The operating point of switching may be set so as to fall within the range of Harmonics Distortion).

(Fourth Embodiment) FIG. 10 shows a circuit configuration of the present embodiment, and the basic configuration is the same as that of FIG. 2 showing the first embodiment. Is omitted. In the present embodiment, the control circuit 4 that drives the switching elements Q1 and Q2 will be described. The control circuit 4 is
The voltage instruction signal S1 output from the dimmer 3 and the feedback signal S2 of the DC voltage Vdc across the capacitor C1
P to control the switching operation of the switching element Q2 so that the DC voltage Vdc becomes the target voltage.
The PWM circuit 4d that outputs the WM signal S4 and the delay element τ
And a delay circuit 4f having a delay circuit 4f and a switching signal S3 of the dimmer 3 are continuously variable in accordance with a switching signal S3 ′ input through the delay circuit 4f, and the operation of the DC power supply unit 1 is operated by a step-up chopper circuit. Alternatively, P is an oscillator that outputs a PWM signal S5 for switching to the operation of the buck-boost chopper circuit.
PW output from the WM circuit 4e and the PWM circuits 4d and 4e
An AND circuit IC1 that performs a logical AND operation of the M signals S4 and S5 and outputs a signal S6, and a P output by the PWM circuit 4e.
A logical NOT circuit IC2 that outputs a signal S7 that is the logical negation of the WM signal S5, an AND circuit IC1, and a logical NOT circuit IC
2 and the signals S6 and S7 respectively output, and the signal S8 and the OR circuit IC3 which outputs the signal S8.
And a driver circuit 4g that outputs the gate signal of the switching element Q1 in accordance with the above.

As shown in FIG. 11, the PWM circuit 4e comprises a triangular wave generator 40 and a comparator CP2, and the dimmer 3 is connected to the non-inverting input terminal of the comparator CP2.
From the triangular wave generator 40 is input to the inverting input terminal, and the switching signal S3 ′ from P.
The WM signal S5 is output, and the waveform of each part at this time is shown in FIG. The switching signal S3 ′ is a DC signal, and is PW during the period when the triangular wave St is smaller than the switching signal S3 ′.
The M signal S5 becomes High level, and the PWM signal S5 becomes Low level during the period when the triangular wave St is larger than the switching signal S3 ′.

When the DC power supply unit 1 is operated as a step-up / down chopper circuit, the switching signal S3 'is set to a voltage V2 which is always higher than the triangular wave St, and the PWM signal S5 is always High.
Level. When operating as a step-up chopper circuit, the switching signal S3 'is always a voltage V lower than the triangular wave St.
3, and the PWM signal S5 is always at Low level. When the switching signal S3 ′ has a value between the voltage V2 and the voltage V3, the DC power supply unit 1 operates alternately as a step-up / step-down chopper circuit and an operation as a step-up chopper circuit which are periodically mixed. To do.

FIG. 13 shows the waveforms of the signals S4 to S8. When the PWM signal S5 is Low level, the output signal S6 of the AND circuit IC1 is L regardless of the PWM signal S4.
It becomes the ow level, and the output signal S7 of the logical NOT circuit IC2
Becomes High level, and therefore the logical sum circuit IC3
Output signal S8 is always at a high level, switching element Q1 maintains an on state regardless of whether switching element Q2 is on or off, and DC power supply unit 1 operates as a step-up chopper circuit. In addition, the PWM signal S5 is High
When it is at the h level, the output signal S6 of the AND circuit IC1 is PW.
The signal becomes the same as the M signal S4, the output signal S7 of the logical NOT circuit IC2 becomes the Low level, therefore the output signal S8 of the logical sum circuit IC3 becomes the same signal as the PWM signal S4, and the switching element Q1 becomes the switching element Q1.
As in the case of 2, the DC power supply unit 1 operates as a step-up / down chopper circuit.

As described above, the DC power supply unit 1 uses the PWM signal S
It is possible to switch between the step-up operation and the step-up / step-down operation according to 5, and when the step-up operation is switched to the step-up / step-down operation, the dimmer 3
When the switching signal S3 output by the switch is switched from the low level to the high level and the step-up / down operation is changed to the boosting operation, the switching signal S3 output by the dimmer 3 is switched from the high level to the low level. In addition, PWM
The cycle of the PWM signal S5 output by the circuit 4e is twice or more the cycle of the PWM signal S4 output by the PWM circuit 4d.

Conventionally, when the operation of the DC power supply unit 1 is switched from boosting operation to buck-boost operation or from buck-boost operation to boosting operation (FIG. 14A), a sudden change in input power occurs, Vibration occurred in the DC voltage Vdc at the switching time t1 (FIG. 14B). However, in the present embodiment, as shown in FIG. 15A, when switching from the step-up / step-down operation to the step-up operation (similarly when switching from the step-up operation to the step-up / step-down operation), the switching signal S3 is changed from time t2 to time t3. By switching from the High level to the Low level (FIG. 15 (c)) over time, a control state in which the boosting operation and the buck-boost operation described in FIG. 12 are mixed alternately at times t2 to t3 is generated. (FIG. 15 (a)), by sweeping the mixing ratio, the operation is switched while the DC voltage Vdc is stabilized without oscillation during the operation switching (FIG. 15 (b)). Thus, the DC voltage Vdc
Is stable, the influence on the discharge lamp La can be eliminated.

By adjusting the delay element τ of the delay circuit 4f according to the feedback response of the DC voltage Vdc, the sweep speed can be adjusted and the stability at the time of operation switching can be secured.

(Fifth Embodiment) FIG. 16 shows a circuit configuration of the present embodiment, and the basic configuration is the same as that of FIG. 2 showing the first embodiment. Is omitted. In the present embodiment, the control circuit 4 that drives the switching elements Q1 and Q2 will be described. The control circuit 4 is
A low-pass filter 4h for removing noise appearing in the DC voltage Vdc across the capacitor C1 and obtaining a feedback signal S2 of the DC voltage Vdc suitable for control, and a resistor R1 connected between the low-pass filter 4h and the ground. When,
A resistor R2 having one end connected to a connection point between the low-pass filter 4h and the resistor R1, a resistor R3 having one end connected to the dimmer 3, and the other end of the resistor R2 connected to the non-inverting input terminal, Operational amplifier OP in which the other end of the resistor R3 is connected to the inverting input terminal
1, a resistor R4 connected between the output terminal and the inverting input terminal of the operational amplifier OP1, a triangular wave generator 4i that outputs a triangular wave signal, and an attenuator 4j that attenuates the triangular wave signal by 1 / √2. Operational amplifier OP connected to the inverting input terminal
Comparator CP3 for comparing the differential output of 1 with the triangular wave signal attenuated by 1 / √2 times by the attenuator 4j connected to the non-inverting input terminal, and the operational amplifier O connected to the inverting input terminal
A comparator CP4 for comparing the differential output of P1 with a triangular wave signal connected to the non-inverting input terminal, and a comparator CP
The output terminal of 3 is connected to the fixed contact A, and the comparator CP
A switching device 4k in which the output terminal of 4 is connected to the fixed contact B and a switching device 4m in which the constant voltage Vcc is connected to the fixed contact A and the output of the switching device 4k is connected to the fixed contact B and the output of the switching device 4m. A driver circuit 4g that outputs the gate signal of the switching element Q1 accordingly. Switch 4k, 4m
Switches the movable contact to the contact A or B by the switching signal S3 output from the dimmer 3, and the gate of the switching element Q2 is connected to the output of the switch 4k.

In the present embodiment, when a constant power is supplied to the discharge lamp La, the ON time of the switching element when the operation of the DC power supply unit 1 is the operation of the step-up chopper circuit is the same as the operation of the DC power supply unit 1. It is noted that it is 1 / √2 times the ON time of the switching element when operating the step-up / down chopper circuit. This will be described below.
AC power supply with one switching of the switching element (when the boosting operation is performed, the switching element Q2 performs switching while maintaining the ON state of the switching element, and during the step-up / down operation, both switching elements Q1 and Q2 perform similar switching). Regarding the energy output from Vs to the load (discharge lamp La) via the inductor L1, the output energy during the boosting operation is shown in FIG. 17 (a), and the output energy during the buck-boost operation is shown in FIG. 17 (b). . Figure 1
In the step-up operation shown in FIG. 7A, the switching on time is Ton1, the off time is Toff1, the inductor current peak value il1, and the input voltage of the DC power supply unit 1 is Vi.
n, and the output DC voltage is Vdc, Vdc = 2 ×
When Vin and Ton1 = Toff1, il1 = α × To
n1 (α is the slope). In this boosting operation, the shaded area S1 of the graph is equal to the output energy, and S1 = 1
/ 2 × Ton1 × il1 = 1/2 × α × Ton1 ² .

Next, in the step-up / down operation shown in FIG. 17B, the on time of switching is Ton2, the off time is Toff2, the peak value il2 of the inductor current, the input voltage of the DC power supply unit 1 is Vin, and it is output. DC voltage is Vd
If c, Vdc = 2 × Vin, Ton2 = 2 × To
When ff2, il2 = α × Ton2 (α is a slope). In this boosting operation, the shaded area S2 of the graph is equal to the output energy, and S2 = 1/4 × Ton2 × il
2 = 1/4 × α × Ton2 ² .

Therefore, when Ton1 = Ton2, the output energy during the boosting operation is twice the output energy during the step-up / down operation. Here, if the respective output energies during the boosting operation and the buck-boost operation are made equal, Ton
The relationship between 1 and Ton2 is 1/2 × α from S1 = S2
X Ton1 ² = 1/4 x α x Ton2 ² and therefore the relationship Ton1 = 1 / √2 x Ton2,
When supplying a constant power to the discharge lamp La, the DC power supply unit 1
The ON time of the switching element when the operation of is the operation of the step-up chopper circuit is 1 / √2 times the ON time of the switching element when the operation of the DC power supply unit 1 is the operation of the buck-boost chopper circuit.

The operation of the circuit shown in FIG. 16 during the step-up / step-down operation will now be described. When the DC voltage Vdc is set to ½ or less of the maximum output voltage, the dimmer 3 sets the switching signal S3 to B
Then, the movable contacts of the switching devices 4k and 4m are switched to the B contact side. That is, the output of the switch 4k is the comparator C
It becomes the output of P4, and the output of the switch 4m becomes the output of the switch 4k, that is, the output of the comparator CP4.

Operational amplifier OP1 and resistors R2, R3 and R4
Constitutes a differential amplifier, amplifies the difference between the voltage instruction signal S1 output from the dimmer 3 and the feedback signal S2 obtained by dividing the DC voltage Vdc, and the comparator CP4
The triangular wave signal of the triangular wave generator 4i is compared with the output of the differential amplifier to output a PWM signal, the switching element Q2 is turned on / off via the switch 4k, and the switches 4k, 4k
m, the switching element Q1 via the driver circuit 4g
A voltage control negative feedback circuit is configured by turning on and off the target voltage indication value (voltage indication signal S1).
The PWM signal is corrected so that the DC voltage Vdc corresponds to.

Next, the operation during the boosting operation will be described. When the DC voltage Vdc is set to ½ or more of the maximum output voltage, the dimmer 3 sets the switching signal S3 to the A state, and the switching device 4
Switch each movable contact of k and 4m to the A contact side. That is, the output of the switch 4k becomes the output of the comparator CP3, and the output of the switch 4m becomes the constant voltage Vcc. Therefore, the constant voltage Vcc is input to the driver circuit 4g, and the switching element Q1 maintains the ON state.

The comparator CP3 has a 1 / attenuator 4j.
A voltage-controlled negative feedback circuit is configured by comparing the triangular wave signal attenuated by √2 times with the output of the differential amplifier, outputting a PWM signal, and turning on / off the switching element Q2 via the switch 4k. Therefore, the PWM signal is corrected so that the DC voltage Vdc corresponds to the target voltage instruction value (voltage instruction signal S1).

As described above, during the boosting operation, the output pulse width of the comparator CP3 becomes 1 / √2 times the output pulse width of the comparator CP4 due to the triangular wave signal attenuated by 1 / √2 times by the attenuator 4j. You can get what you want. As a result, there is no change in the input power immediately after switching between the step-up operation and the step-up / step-down operation of the DC power supply unit 1, the vibration of the DC voltage Vdc immediately after the operation switching is eliminated, and smooth step-up / step-down operation can be performed. it can.

[0058]

The invention of claim 1 has a diode bridge for converting the voltage of an AC power supply into a DC voltage, and a switching element, and a DC voltage output by the diode bridge by turning on / off the switching element. To a desired voltage, a capacitor for smoothing the output of the DC power supply unit, an inverter unit for converting the voltage of the capacitor into a high frequency voltage, and a high frequency voltage output by the inverter unit. A discharge lamp, a control circuit for controlling the on / off operation of the switching element of the DC power supply unit, and when the voltage of the capacitor is equal to or higher than a predetermined voltage, the operation of the DC power supply unit is switched to the operation of a boost chopper circuit, When the voltage of the capacitor is below a predetermined voltage,
Since the switching means switches the operation of the DC power supply section to the operation of the step-up / step-down chopper circuit, the efficiency in the step-up operation is improved as compared with the conventional step-up / step-down chopper circuit, thereby adjusting the DC voltage. Thus, there is an effect that the efficiency of voltage conversion at the time of dimming can be improved, and particularly when the power supply voltage of the AC power supply is low (for example, 100 V), the range in which the efficiency is improved becomes wide.

According to a second aspect of the present invention, in the first aspect of the present invention, the switching means always causes the operation of the DC power supply unit to be the operation of the step-up / down chopper circuit when the voltage of the AC power supply is equal to or higher than a predetermined voltage. Since it is switched, it is possible to adjust the dimming by the DC voltage output from the DC power supply unit even when the power supply voltage of the AC power supply is high (for example, 242V), and thus widen the range of usable power supply voltage. There is an effect that can be.

According to a third aspect of the present invention, in the first or second aspect of the invention, the voltage of the AC power source is set to about 100V, and the switching means operates the DC power source unit so that the voltage of the capacitor is about 200V or more. At that time, the operation is switched to the step-up chopper circuit, and when the voltage of the capacitor is approximately 200 V or less, the operation is switched to the step-up / step-down chopper circuit. There is an effect that it is possible to further improve the efficiency of voltage conversion when performing.

According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the voltage of the capacitor when the switching means switches the operation of the DC power supply unit to the operation of the step-up chopper circuit or the step-up / step-down chopper circuit, Since the total harmonic distortion rate of the output current of the AC power supply is set to be a predetermined value or less, there is an effect that the input current distortion of the device can be improved.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the switching means controls the ON / OFF timing of the switching element of the DC power source section, so that the control circuit controls the switching element. Since the operation of the DC power supply section is switched to the operation of the step-up chopper circuit or the step-up / step-down chopper circuit, the switching element of the DC power supply section can also serve as the switching means, and the control circuit can be easily configured. is there.

According to a sixth aspect of the present invention, in any one of the first to fifth aspects of the present invention, the DC power supply unit includes two or more switching elements, and the two or more switching elements have a common ground level. Therefore, there is an effect that a control circuit for driving the switching element can be easily configured.

According to a seventh aspect of the present invention, in the fifth or sixth aspect of the invention, the DC power supply unit includes two or more switching elements, and the control circuit controls the on / off timing of one switching element. By doing so, the operation of the DC power supply unit is switched to the operation of the step-up chopper circuit or the step-up / step-down chopper circuit, so that the switching means only needs to control one switching element, and the switching means can be easily configured. There is.

According to an eighth aspect of the present invention, in the seventh aspect, the DC power supply unit includes two switching elements, and the control circuit includes a comparator for comparing a voltage of the capacitor with a reference voltage, and the comparator. It is provided with two drive circuits having mutually different drive signals for turning on / off the switching element, and a switch for switching the drive circuit of one of the switching elements to one of the two drive circuits according to the comparison result of the comparator. Since the other switching element is always turned on / off by one of the two driving circuits, the voltage of the capacitor at the time of switching the operation of the DC power supply unit is arbitrarily set by the reference voltage input to the comparator. The effect is that it can be set.

According to a ninth aspect of the present invention, in the invention according to any one of the first to eighth aspects, the switching means switches the operation of the DC power supply unit to the operation of the step-up chopper circuit or the step-up / step-down chopper circuit. Between each operation period of the step-up / step-down chopper circuit and the step-up / step-down chopper circuit, a period for alternately performing each operation of the step-up chopper circuit and the step-up / step-down chopper circuit is provided. It is possible to reduce the change, stabilize the DC voltage output from the DC power supply unit, and eliminate the influence on the discharge lamp.

In a tenth aspect of the present invention according to any one of the fifth to eighth aspects, when the discharge lamp is supplied with a constant electric power, the control circuit controls the operation of the DC power supply unit to operate the step-up chopper circuit. Since the ratio of the ON time of the switching element at the time of the above and the ON time of the switching element at the time of operating the DC power supply unit as the operation of the step-up / down chopper circuit is made constant, the same effect as that of claim 9 is obtained. Play.

According to an eleventh aspect of the invention, in the invention of the tenth aspect, the ON time of the switching element when the operation of the DC power supply unit is the operation of the step-up chopper circuit is the same as the operation of the DC power supply unit. Since it is 1 / √2 times the ON time of the switching element when operating the circuit, there is no sudden change in the input power when switching the operation of the DC power supply, and the DC voltage output by the DC power supply is eliminated. There is an effect that it can be stabilized and the influence on the discharge lamp can be eliminated.

[Brief description of drawings]

FIG. 1 is a block configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit configuration diagram showing a first embodiment of the present invention.

3A to 3C are waveform charts for explaining the operation of the first embodiment of the present invention.

FIG. 4 is a circuit configuration diagram showing a control circuit according to the first embodiment of the present invention.

FIG. 5 is a circuit configuration diagram showing a second embodiment of the present invention.

6 (a) to 6 (c) are waveform charts for explaining the operation of the second embodiment of the present invention.

FIG. 7 is a circuit configuration diagram showing a third embodiment of the present invention.

8A to 8C are waveform charts for explaining the operation of the third embodiment of the present invention.

FIG. 9 is another circuit configuration diagram showing the third embodiment of the present invention.

FIG. 10 is a circuit configuration diagram showing a fourth embodiment of the present invention.

FIG. 11 is a circuit configuration diagram showing a PWM circuit according to a fourth embodiment of the present invention.

FIG. 12 is a waveform diagram illustrating the operation of the PWM circuit according to the fourth embodiment of the present invention.

FIG. 13 is a waveform diagram illustrating the operation of the fourth embodiment of the present invention.

14A and 14B are DC voltage waveform diagrams output by a conventional discharge lamp lighting device.

15 (a) and 15 (b) are DC voltage waveform diagrams output by Embodiment 4 of the present invention. (C) A waveform diagram of a switching signal according to the fourth embodiment of the present invention.

FIG. 16 is a circuit configuration diagram showing a fifth embodiment of the present invention.

FIG. 17 (a) is a diagram showing output energy during a boosting operation according to the fifth embodiment of the present invention. (B) It is a figure showing the output energy at the time of buck-boost operation of Embodiment 5 of this invention.

FIG. 18 is a circuit configuration diagram showing a first conventional example.

FIG. 19 is a circuit configuration diagram showing a second conventional example.

FIG. 20 is a circuit configuration diagram showing a third conventional example.

FIG. 21 is a circuit configuration diagram showing a fourth conventional example.

[Explanation of symbols]

1 DC power supply 2 Inverter section 3 dimmer 4 control circuit 10 Boost chopper circuit 11 Buck-boost chopper circuit 12 Switching means DB diode bridge C1 capacitor

Continued front page    F term (reference) 3K072 AA01 AB09 BA05 BB01 CA11                       CA16 DE05 GA02 GB01 GB03                       HA02 HA10                 3K098 CC24 CC41 CC56 CC57 CC60                       DD25 DD35 DD43 EE32 EE35                       FF01 FF14 GG03                 5H730 AA14 AS11 BB13 BB14 BB86                       CC01 DD04 DD34

Claims (11)

[Claims] 1. A diode bridge for converting a voltage of an AC power supply into a DC voltage, and a switching element. By turning on / off the switching element, a DC voltage output from the diode bridge is converted into a desired voltage. DC power supply unit, a capacitor for smoothing the output of the DC power supply unit, an inverter unit for converting the voltage of the capacitor into a high frequency voltage, a discharge lamp supplied with the high frequency voltage output by the inverter unit, and the DC power supply A control circuit for controlling the on / off operation of the switching element of the unit, and when the voltage of the capacitor is equal to or higher than a predetermined voltage, the operation of the DC power supply unit is switched to the operation of a boost chopper circuit, and the voltage of the capacitor is set to a predetermined value. And a switching means for switching the operation of the DC power supply unit to the operation of the buck-boost chopper circuit when the voltage is less than or equal to the voltage. Discharge lamp lighting device. 2. The switching means always switches the operation of the DC power supply section to the operation of the step-up / down chopper circuit when the voltage of the AC power supply is equal to or higher than a predetermined voltage. Discharge lamp lighting device. 3. The voltage of the AC power supply is set to about 100V,
The switching means switches the operation of the DC power supply unit to the operation of the step-up chopper circuit when the voltage of the capacitor is approximately 200 V or more, and the operation of the step-up / down chopper circuit when the voltage of the capacitor is approximately 200 V or less. The discharge lamp lighting device according to claim 1, wherein the discharge lamp lighting device is switched. 4. The voltage of the capacitor when the switching means switches the operation of the DC power supply unit to the operation of the step-up chopper circuit or the step-up / step-down chopper circuit is such that the total harmonic distortion rate of the output current of the AC power supply is predetermined. The discharge lamp lighting device according to claim 1 or 2, wherein the discharge lamp lighting device is set to be equal to or less than a value. 5. The switching means controls the operation of the DC power supply unit by operating the step-up chopper circuit or the step-up / down chopper circuit by controlling the ON / OFF timing of the switching element of the DC power supply unit by the control circuit. 5. The discharge lamp lighting device according to claim 1, wherein the discharge lamp lighting device comprises: 6. The discharge lamp according to claim 1, wherein the DC power supply unit includes two or more switching elements, and the two or more switching elements have a common ground level. Lighting device. 7. The DC power supply unit includes two or more switching elements, and the control circuit controls the on / off timing of one switching element,
The discharge lamp lighting device according to claim 5 or 6, wherein the operation of the DC power supply unit is switched to the operation of a step-up chopper circuit or a step-up / step-down chopper circuit. 8. The DC power supply unit includes two switching elements, and the control circuit has a comparator for comparing a voltage of the capacitor and a reference voltage and a driving signal for turning on / off the switching element are different from each other. Two drive circuits and a switch for switching the drive circuit of one of the switching elements to one of the two drive circuits according to the comparison result of the comparator, and the other switching element of the two drive circuits is provided. 8. The discharge lamp lighting device according to claim 7, which is constantly turned on / off by one of the drive circuits. 9. The switching means, when switching the operation of the DC power supply unit to the operation of a step-up chopper circuit or a step-up / step-down chopper circuit, between the step-up chopper circuit and the step-up / step-down chopper circuit. 9. The discharge lamp lighting device according to claim 1, wherein a period during which each operation of the circuit and the step-up / down chopper circuit is alternately performed is provided. 10. When a constant power is supplied to the discharge lamp, the control circuit controls the ON time of the switching element when the operation of the DC power supply unit is the operation of the step-up chopper circuit and the DC power supply unit. 9. The discharge lamp lighting device according to claim 5, wherein a ratio with an ON time of the switching element when the operation is the operation of the step-up / down chopper circuit is constant. 11. The ON time of the switching element when the operation of the DC power supply unit is the operation of the step-up chopper circuit,
The discharge lamp lighting device according to claim 10, wherein the ON time of the switching element when the operation of the DC power supply unit is the operation of the step-up / down chopper circuit is 1 / √2 times.