JP2002216988A - Electric discharge lamp lighting equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a resonance phenomenon of a LC filter, which may be generated when a load circuit is in a no-load state, even if the LC filter is prepared in an output of the DC-DC conversion circuit. SOLUTION: It has the load circuit 1 containing an electric discharge lamp 11, a direct-current power supply 2, a DC-DC conversion circuit 3 that has a switching element SW3 and the like, to turn ON/OFF according to a control signal, and an output control circuit 4, which detects this output or the like and outputs the above control signal using this detection result. The output control circuit 4 adjusts it using the above detection result by a switching frequency or a duty to the switching element SW3, in the no-load state, where the electric discharge lamp 11 has gone out. That is, reducing an amount of energies sent to the output side by one time of the switching, and shortening a cycle of an intermittent switching by shortening time, which the output voltage falls to a predetermined over voltage detection level or less, suppress the above resonance phenomenon.

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 having a DC-DC conversion circuit for converting a DC power supply to a voltage required by a discharge lamp, and for stably lighting the discharge lamp.

[0002]

2. Description of the Related Art FIG. 13 shows a configuration diagram of a conventional discharge lamp lighting device (see, for example, JP-A-2000-340385), and FIG.
As shown in FIG.

In FIG. 13, a discharge lamp lighting device includes a load circuit 1 including a discharge lamp 11, a DC power supply 2, a DC power supply from the DC power supply 2, and a DC power of an output level corresponding to a control signal. DC-DC conversion circuit 3 for converting the DC power into DC power and outputting the converted DC power to load circuit 1
A PA and an output control circuit 4PA for detecting the output of the DC-DC conversion circuit 3PA and outputting the control signal using the detection result. Note that the DC power supply 2
In some cases, the power supply circuit may be constituted by a battery, or may be constituted by a power supply circuit for obtaining DC power by rectifying and smoothing AC power from a commercial power supply.

As the discharge lamp 11 included in the load circuit 1, for example, a high-intensity discharge lamp is used. In this case, the load circuit 1 is further provided with an inverter circuit 12 and a starting circuit 13. The inverter circuit 12 is a full-bridge FET connected to the output of the DC-DC conversion circuit 3PA.
Q1 to Q4, and a drive circuit 121 that performs switching control of the FETs Q1 to Q4, converts DC power from the DC-DC conversion circuit 3PA into AC power, and supplies the AC power to the discharge lamp 11. I have. here,
For example, if the control of turning on / off the set of FETs Q1 and Q4 and the set of FETs Q2 and Q3 alternately is performed, DC-DC
DC power from conversion circuit 3PA can be converted to AC power.

[0005] The starting circuit 13 is interposed between the inverter circuit 12 and the discharge lamp 11, and generates a high-voltage pulse and applies it to the discharge lamp 11 when the discharge lamp 11 is turned off.

The DC-DC conversion circuit 3PA includes a primary winding n3
A transformer T3 having primary and secondary windings n32, and a primary winding n31 of the transformer T3 are connected in series to the output of the DC power supply 2 and control signals from an output control circuit 4PA ("SW" in FIGS. 14 and 15). Control signal "), the switching element SW3 is turned on / off according to a transistor, for example, and a diode D30 and a capacitor C30 are connected in series to both ends of a secondary winding n32 of a transformer T3. Output terminal. In the example of FIG.
In the DC conversion circuit 3PA, the voltage of the DC power supply 2 is stepped up and down to a voltage required for stably lighting the discharge lamp 11, and the output of the discharge lamp lighting device is adjusted mainly by the DC-DC conversion circuit 3PA. Has become.

[0007] The output control circuit 4PA includes a detection unit 41, a command creation unit 42, a comparison unit 43, an oscillation circuit 44, and a maximum off-time variable signal generation circuit 45.

[0008] The detection unit 41 is composed of amplifiers 411 and 412, and detects the output voltage and output current of the DC-DC conversion circuit 3PA, and outputs these detection results via the amplifiers 411 and 412, respectively. , Primary winding n31 and secondary winding n of transformer T3
32 and primary current I1 and secondary current I2
Is to be detected.

The command creating section 42 includes a DC-DC conversion circuit 3
A power command value generating circuit 421 for generating a power command value for determining the output power of the PA, and a current command value for obtaining a current command value to be a control target of the output current through calculation from a detection result of the output voltage and the power command value An arithmetic unit 422 and an error amplifier 423 that creates a primary peak current command from the detection result of the output current and the current command value.
This is to create a secondary peak current command.

The comparing section 43 includes comparators 431 to 43
3 for each detection result by the detection unit 41.
To compare and generate various signals based on these comparison results.
Things. The comparator 431 detects the primary current I1
Non-inverted detection result and primary peak current command
Input to the input terminal and the inverted input terminal, as shown in FIG.
A reset signal is output as in “output of 431”. Ko
The comparator 432 is in a state where the non-inverting input terminal is grounded.
Then, the detection result of the secondary current I2 is input to the inverting input terminal,
A set signal is output as in “432 output” shown in FIG.
Power. The comparator 433 outputs the output of the detection unit 41
Voltage detection result and predetermined reference voltage V_{R- NL}Each
Input to the non-inverting input terminal and the inverting input terminal.
As shown in “433 output”, switching is permitted (L
Level) / SW permission indicating switching prohibited (H level)
Outputs a no signal.

The oscillation circuit 44 includes a flip-flop (SR
-FF) 441, each of which includes various logic circuits and a timer, and has functions of a minimum on-time limit, a maximum on-time limit, a minimum off-time limit, and a maximum off-time limit.
A control signal for turning on / off the switching element SW3 is output from the Q terminal of the flip-flop 441 according to various signals from the comparing unit 43. The maximum off time variable signal generation circuit 45 adjusts the control value of the maximum off time of the oscillation circuit 44 according to the input / output state.

Basically, the output control circuit 4PA has a DC-
A lamp current and a lamp voltage are detected at an output terminal of the DC conversion circuit 3PA, and on / off control of the switching element SW3 is performed by feedback control based on these detection results and a power command. As shown in FIG. 14, in order to improve the circuit efficiency in accordance with the SW control signal of the output control circuit 4PA, the switching element SW3 is
It turns on after turning on for a predetermined time, that is, until it reaches the primary side peak current command, and turns on again when the current I2 discharged to the secondary side becomes zero. Hereinafter, this operation is called a boundary mode operation. In the case of driving the switching element SW3, the PWM signal is variable in both frequency and duty.

The functions of the oscillation circuit 44 are provided for the following reasons. That is, when the load is the discharge lamp 11 as in the example of FIG. 13, the load voltage fluctuates greatly,
When the DC power supply 2 is a battery or the like and the voltage fluctuates over a wide range, the frequency fluctuates over a wide range. When the boundary mode operation is performed in a state where the lamp temperature is low, such as immediately after starting, the inductor (T
3) The time required for the magnetic energy stored in 3) to flow out to the load circuit 1 side as a current increases, and the switching frequency decreases to enter the audible range or the peak current increases, so that the transformer T3 is increased in size. Need to be done.
For this reason, in the discharge lamp lighting device of FIG. 13, the value of the maximum off-time is set to a predetermined value in order to prevent the above-described fluctuation and increase in the size of the transformer T3. When the off time reaches the maximum off time, the mode shifts to a mode in which the switching element SW3 is forcibly turned on again to operate. As a result, a large decrease in the switching frequency can be prevented. Less than,
The operation in this mode is called a continuous mode operation.

Conversely, in order to prevent an increase in switching loss due to an excessively high switching frequency, the minimum value of the on / off time of the switching element SW3 is set to a predetermined value, and a current flows through the transformer T3. When the period becomes shorter than the predetermined switching period, the transformer T3 is operated in a mode in which there is a period in which no current flows in either the primary or secondary of the transformer T3. Hereinafter, this mode of operation is referred to as a discontinuous mode operation.

Further, in order to cope with a wide range of load fluctuation and power supply fluctuation and to perform a stable switching operation, an on / off switch is provided.
The maximum value / minimum value of the off period is adjusted to a predetermined value according to the state.

In particular, even when the power is turned on and the circuit starts operating, the discharge lamp 11 is in a non-load state in which the discharge lamp 11 is turned off.
The output of the DC-DC conversion circuit 3PA is excessively boosted. For this reason, in the discharge lamp lighting device of FIG. 13, as shown in FIG. 15, the comparator 433 compares the detection result of the output voltage, and the level of the detection result of the output voltage exceeds the predetermined overvoltage detection level. And an oscillation circuit (PWM
The set value of the minimum off time of the oscillation circuit 44 is shifted to substantially infinity, and the output of the on signal is prohibited. Due to this intermittent switching operation, the switching element SW3 does not turn on until the output voltage becomes equal to or lower than the overvoltage detection level due to the leakage current of the circuit or a small power consumption of the detection circuit, the drive circuit 121, and the like, thereby preventing excessive boosting. Because

[0017]

However, FIG.
In the output of the DC-DC converter 3A having the configuration shown in FIG. 17, an LC filter F3 for reducing ripples is provided, and the output of the DC-DC converter 3 having the configuration shown in FIG. LC to reduce
In the case where the filter F3 is provided, when an intermittent switching operation is performed to prevent excessive boosting at the time of no load and the period of the intermittent oscillation approaches the resonance period of the LC filter 3, as shown in FIG. A resonance phenomenon may occur in the output voltage after the LC filter F3, and an excessive voltage may be generated.

For this reason, if the time constant of the LC filter F3 is increased so that the resonance period is much larger than the intermittent oscillation period, the resonance phenomenon can be suppressed, but the inductor L _F3 and the capacitor C constituting the LC filter F3 can be suppressed. _F3 will be enlarged.

The present invention has been made in view of the above circumstances, and even if an LC filter is provided at the output of a DC-DC conversion circuit, resonance of the LC filter which may occur when the load circuit is in a no-load state is provided. An object of the present invention is to provide a discharge lamp lighting device capable of suppressing the phenomenon.

[0020]

According to a first aspect of the present invention, there is provided a discharge lamp lighting apparatus including a load circuit including a discharge lamp, a DC power supply, and a switching element.
By turning on / off the switching element according to the control signal, the DC power is taken from the DC power supply and converted into DC power of an output level according to the control signal,
A DC-DC conversion circuit that outputs the converted DC power to the load circuit via an LC filter;
An output control circuit that detects the output of the C conversion circuit and outputs the control signal using the detection result. The output control circuit detects the output voltage of the DC-DC conversion circuit. In a no-load state in which the discharge lamp is off, when the detection result of the output voltage reaches a predetermined first voltage, on / off control of the switching element is performed intermittently, and the detection result of the output voltage is obtained. Is adjusted so as not to exceed the first voltage, and the on-duty for at least the switching element is reduced as the detection result of the output voltage is higher.

According to a second aspect of the present invention, in the discharge lamp lighting device according to the first aspect, the output control circuit, in the no-load state, detects a second voltage lower than the first voltage as a result of detecting the output voltage. , The on-duty for at least the switching element is reduced.

According to a third aspect of the present invention, in the discharge lamp lighting device according to the first aspect, the output control circuit, in the no-load state, switches on-duty with respect to the switching element in accordance with at least a detection result of the output voltage. Is continuously changed.

According to a fourth aspect of the present invention, there is provided a discharge lamp lighting device,
A load circuit including a discharge lamp, a DC power supply, and a switching element. The switching element is turned on / off in accordance with a control signal, thereby taking in DC power from the DC power supply and obtaining an output level corresponding to the control signal. A DC-DC conversion circuit that converts the DC power into DC power, and outputs the converted DC power to the load circuit via an LC filter, and detects the output of the DC-DC conversion circuit, and utilizes the detection result. And an output control circuit for outputting the control signal. The output control circuit detects an output voltage of the DC-DC conversion circuit, and outputs the output voltage in a no-load state in which the discharge lamp is turned off. Is the predetermined first
When the voltage is reached, the on /
Off control is performed intermittently so that the detection result of the output voltage does not exceed the first voltage, and the higher the detection result of the output voltage, the higher the switching frequency for at least the switching element. Features.

According to a fifth aspect of the present invention, in the discharge lamp lighting device according to the fourth aspect, the output control circuit is configured such that, in the no-load state, a detection result of the output voltage is lower than the first voltage. , The switching frequency for at least the switching element is increased.

According to a sixth aspect of the present invention, in the discharge lamp lighting device according to the fourth aspect, the output control circuit, in the no-load state, switches a switching frequency for the switching element at least according to a result of detection of the output voltage. Is continuously changed.

According to a seventh aspect of the present invention, in the discharge lamp lighting device according to any one of the first to sixth aspects, in the no-load state, the higher the detection result of the output voltage is, the higher the output voltage is. The on-duty for the switching element is reduced, and the switching frequency for the switching element is increased.

According to an eighth aspect of the present invention, in the discharge lamp lighting device according to the seventh aspect, in the no-load state, the output control circuit detects the second voltage whose detection result of the output voltage is lower than the first voltage. When the output voltage exceeds the third voltage, the on-duty for the switching element is reduced, and when the detection result of the output voltage exceeds a third voltage lower than the first voltage, the switching frequency for the switching element is increased.

According to a ninth aspect of the present invention, in the discharge lamp lighting device according to the eighth aspect, the second voltage and the third voltage are at the same level.

According to a tenth aspect of the present invention, in the discharge lamp lighting device according to the eighth aspect, the second voltage is higher than the third voltage.

According to an eleventh aspect of the present invention, in the discharge lamp lighting device according to the eighth aspect, the third voltage is higher than the second voltage.

According to a twelfth aspect of the present invention, in the discharge lamp lighting device according to the eighth aspect, the output control circuit, in the no-load state, responds to the detection result of the output voltage.
A switching frequency and an on-duty for the switching element are continuously changed.

The invention according to claim 13 is the invention according to claims 1 to 12
In the discharge lamp lighting device according to any one of the above, in the no-load state, when the detection result of the output voltage is substantially at the level of the first voltage, the DC- The circuit is set such that the time for consuming the same amount of energy as the amount of energy output from the DC conversion circuit to the load circuit due to the circuit loss in the no-load state is sufficiently smaller than the resonance cycle of the LC filter. It is characterized by having been done.

The invention according to claim 14 is the invention according to claims 1 to 13
In the discharge lamp lighting device according to any one of the above,
-A multiplying voltage rectifier circuit having an input connected to an alternating voltage point in the DC conversion circuit, wherein the output control circuit detects the output voltage in the no-load state substantially at a level of the first voltage; The on / off control of the switching element is performed so that the output of the multiple voltage rectification circuit does not exceed a predetermined fourth voltage until the voltage reaches the predetermined voltage.

According to a fifteenth aspect of the present invention, in the discharge lamp lighting device according to the fourteenth aspect, the output control circuit operates at a switching frequency equal to or less than a predetermined value until the detection result of the output voltage reaches the second voltage. By performing on / off control on the switching element, an increase in the output voltage of the multiple voltage rectifier circuit is suppressed, and when the detection result of the output voltage exceeds the second voltage, switching to the switching element is performed. By increasing the frequency,
The multiplying voltage rectifier circuit is characterized by accelerating an increase in output voltage.

The invention according to claim 16 is the invention according to claims 1 to 15
5. The discharge lamp lighting device according to claim 1, wherein the output control circuit changes an on-duty for the switching element with respect to a voltage of the DC power supply.

According to a seventeenth aspect of the present invention, in the discharge lamp lighting device according to the sixteenth aspect, the output control circuit changes an on-duty for the switching element in inverse proportion to a voltage of the DC power supply. It is characterized by.

[0037]

FIG. 1 is a block diagram of a discharge lamp lighting device according to a first embodiment of the present invention.
An embodiment will be described.

The discharge lamp lighting device shown in FIG.
13 and a DC power supply 2 in the same manner as the discharge lamp lighting device of FIG. 13, and a difference from the discharge lamp lighting device of FIG. 13 is that a DC-DC conversion circuit 3 and an output control circuit 4 are provided. ing.

The DC-DC conversion circuit 3 has a primary winding n31.
And a transformer T3 having a secondary winding n32, a switching element SW3 connected in series with the output of the DC power supply 2 together with the primary winding n31 of the transformer T3, and turned on / off according to a control signal from the output control circuit 4. The connection point between the switching element SW3 and the primary winding n31 and 2
Capacitor C3 connected between one end of next winding n32
1, a diode D31 connected between the other end of the secondary winding n32 and the ground, and an LC filter F3. The LC filter F3 includes an inductor L _F3 connected in series between one end of the secondary winding n32 and the ground.
And it is constituted by a capacitor C _F3, the capacitor C _F3
Are the output terminals of the DC-DC conversion circuit 3.

The output control circuit 4 includes a detection unit 41, a command creation unit 42, a comparison unit 43, an oscillation circuit 44, and a maximum off-time variable signal generation circuit 45 in the same manner as the output control circuit 4PA of FIG. The lighting control circuit 46 is provided as a different point from the output control circuit 4PA.

The lighting determination circuit 46 determines whether or not the discharge lamp 11 is turned off and the load circuit 1 is in a no-load state based on the detection result of the output voltage by the detection unit 41. If ON / OFF in the oscillation circuit 44
The off control value is switched to a predetermined value at the time of no-load operation.

When the load circuit 1 is in a no-load state, DC
-Since the output of the DC conversion circuit 3 is almost zero and the primary peak current shows the maximum, the on-time of the switching element SW3 can be adjusted by the function of limiting the maximum on-time, and since the output voltage is high, the secondary The time during which the current I2 flows is short, and the off time of the switching element SW3 can be adjusted with the minimum off time. That is, at no load, the switching frequency and the duty can be adjusted by these two limit values.

By the way, in order to suppress the resonance phenomenon of the output voltage shown in FIG.
What is necessary is just to make it shorter than the resonance period of C filter F3. Now
The switching cycle at the time of no load is T _SW , the resonance cycle of the LC filter 3 is T _LC , the energy transmitted to the output side by one switching is E _P , and the circuit consumed from the output terminal in the same switching cycle. E _L
When (1 + E _P / E _L ) × T _SW << T _LC is satisfied, the energy transmitted to the output side is adjusted by the switching frequency or the duty in one switching operation under no load. That is, the amount of energy sent to the output side by one switching is reduced,
By shortening the time during which the output voltage falls below the overvoltage detection level, the cycle of intermittent switching is shortened. By switching the switching frequency or duty to a predetermined value so that such a switching condition is satisfied when the load circuit 1 is in a no-load state, the resonance phenomenon shown in FIG. 18 can be suppressed.

In the example shown in FIG. 1, the switching to the no-load operation by the lighting determination is performed using the detection result of the output voltage. A configuration using both detection results of the output voltage may be adopted.

FIG. 2 is a configuration diagram of a discharge lamp lighting device according to a second embodiment of the present invention. The second embodiment will be described with reference to FIG.

The discharge lamp lighting device shown in FIG.
And a DC power supply 2 and a DC-DC conversion circuit 3 as in the first embodiment, and an output control circuit 4A as a difference from the first embodiment.

The output control circuit 4A includes a detection unit 41, a command generation unit 42, and a lighting determination circuit 46 similar to those in the first embodiment, and includes comparators 431 and 43.
3, a frequency adjustment circuit 47 and an oscillation circuit 44A.

The frequency adjusting circuit 47 outputs a switching frequency command signal in accordance with the detection results of the primary current I1 and the secondary current I2 by the detecting section 41 and the no-load mode switching signal from the lighting discriminating circuit 46. It is.

The oscillation circuit 44A includes a flip-flop 44
1, an oscillator 442, various logic circuits, etc., and various signals from the comparison unit 43A and a frequency adjustment circuit 47
And outputs a control signal for turning on / off the switching element SW3 in response to a switching frequency command signal from the controller.

That is, the switching frequency is
The circuit is configured to turn on the switching element SW3 at the rise of the output signal of the oscillator 442, and to turn off the switching element SW3 when a predetermined current flows to the primary side of the DC-DC conversion circuit 3. It is done. If the switching element SW3 is forcibly turned off at the fall of the output signal of the oscillator 442, the maximum on-time (maximum on-duty) can be determined by the oscillator 442.

When the load circuit 1 is in a no-load state, the output is substantially zero, so that the primary peak current command has the maximum value, and the switching frequency and duty are substantially determined by the condition of the oscillator 442.

In the embodiment shown in FIG. 2, when the lighting circuit 46 detects that the load circuit 1 is in a no-load state, the frequency adjusting circuit 4 is switched to the above-described switching condition.
7, the switching frequency and duty of the oscillator 442 are switched.

FIG. 3 is a configuration diagram of a discharge lamp lighting device according to a third embodiment of the present invention, and FIG. 4 is an operation waveform diagram of the discharge lamp lighting device of FIG. 3, which is used in the third embodiment. Will be described.

The discharge lamp lighting device shown in FIG.
And a DC power supply 2 and a DC-DC conversion circuit 3 as in the second embodiment, and is different from the second embodiment in that an adjustment circuit (FIG.
Then, "SW frequency max. ON-Duty adjustment circuit")
An output control circuit 4B having 47A is provided.

Here, according to the above-described embodiment, DC-
Although the resonance phenomenon of the output of the DC conversion circuit 3 can be suppressed, the output voltage of the DC-DC conversion circuit 3 becomes a predetermined no-load voltage under the above-mentioned switching condition because the loss of the circuit at the time of no load is small. It takes time to ascend to and it takes too long to light up.

Therefore, in the third embodiment, as shown in FIG. 4, until the output voltage becomes a predetermined value lower than the overvoltage detection level (“SW condition switching level” in FIG. 4), “None” shown in FIG. As in the case of the "load duty command", the on-duty is increased, and the boosting speed is increased. When the output voltage exceeds the SW condition switching level, the duty is reduced and the switching condition is switched to the above-described switching condition, whereby the resonance phenomenon in the case of the intermittent switching state can be suppressed.

FIG. 5 is an operation waveform diagram of the discharge lamp lighting device according to the fourth embodiment of the present invention. The fourth embodiment will be described with reference to FIG.

The discharge lamp lighting device of the fourth embodiment has the same configuration as that of the discharge lamp lighting device of the third embodiment except that it has an output control circuit having an adjustment circuit different from the adjustment circuit 47A. That is, in FIG. 4, when the output voltage of the DC-DC conversion circuit reaches the SW condition switching level lower than the overvoltage detection level, the oscillation circuit 44A is adjusted through the adjustment circuit 47A.
Although the switching duty of the switching element SW3 by A is reduced, the energy transmitted to the output side of the DC-DC conversion circuit is reduced, and the resonance phenomenon at the output of the DC-DC conversion circuit is suppressed. As shown in FIG. 5, when the output voltage reaches the SW condition switching level, the adjustment circuit changes the switching frequency of the oscillation circuit 44A for the switching element SW3 as in the “no-load frequency command” shown in FIG. It is raised to a predetermined value. Even with this configuration, it is possible to suppress the resonance phenomenon in the case of the intermittent switching state.

In FIG. 4, the switching duty is switched stepwise with respect to the output voltage by the no-load duty command. However, as shown in FIG. 6, the switching duty is changed by the no-load SW-duty command. A configuration in which the switching duty changes continuously with respect to the output voltage may be used.

In FIG. 5, the switching frequency is switched stepwise with respect to the output voltage by the no-load frequency command. However, as shown in FIG.
A configuration in which the switching frequency continuously changes with respect to the output voltage according to the no-load SW frequency command may be employed.

FIG. 8 is an operation waveform diagram of the discharge lamp lighting device according to the fifth embodiment of the present invention, and the fifth embodiment will be described with reference to FIG.

The discharge lamp lighting device according to the fifth embodiment has the same configuration as the discharge lamp lighting device according to the third embodiment except that an output control circuit having an adjustment circuit different from the adjustment circuit 47A is provided.

As shown in FIG. 8, when the output voltage reaches the SW condition switching level, the adjusting circuit of the fifth embodiment generates an oscillation circuit 44A as shown by a "no-load duty command" shown in FIG. In addition to reducing the switching duty for the switching element SW3, the switching frequency of the oscillation circuit 44A for the switching element SW3 is increased to a predetermined value, as in the “no-load frequency command” shown in FIG. In this way, by switching both the switching frequency and the duty,
During the intermittent switching, the switching element SW3
In this case, the rate of increase of the output voltage when switching is performed can be set finely.

In the example of FIG. 8, the switching of the switching frequency and the duty is performed at the same threshold level, but may be performed at a different threshold level. Also, as shown in FIGS. 6 and 7,
A configuration in which the switching frequency and the duty continuously change with respect to the output voltage may be used.

FIG. 9 is a block diagram of a discharge lamp lighting device according to a sixth embodiment of the present invention, and FIG. 10 is an operation waveform diagram of the discharge lamp lighting device of FIG. Will be described.

The discharge lamp lighting device shown in FIG.
And a DC-DC conversion circuit 3 and an output control circuit 4B in the same manner as in the third embodiment, and a difference from the third embodiment is a load circuit 1A.

This load circuit 1A includes an inverter circuit 12 similar to that of the third embodiment, a multiple voltage rectifier circuit 14 having inputs connected to both ends of a secondary winding n32 of the DC-DC converter circuit 3, and a starting circuit. And a circuit 13A. Starting circuit 13A includes a gap Gap which is connected between one of the output terminals of the inverter circuit 12 of the multi-precision voltage rectifier circuit 14, and a capacitor C _G, both ends of the gap Gap via the capacitor C _G Primary winding n1 connected to
1 and a transformer (pulse transformer) PT1 having a secondary winding n12 interposed between the other output terminal of the inverter circuit 12 and the discharge lamp 11. Here, by Gap is turned on, the primary winding n charge transformer PT1 stored in the capacitor C _G
11, the discharge is rapidly performed, and the high-voltage pulse voltage generated in the secondary winding n12 of the transformer PT1 is applied to the discharge lamp 11, whereby the discharge lamp 11 starts discharging.

[0068] Gap are those voltage of the capacitor C _G is turned on exceeds the breakdown voltage, FIG. 9
In this example, to charge the capacitor C _G, multiple precision voltage rectifier circuit 14, such as a Cockcroft-Walton is used.

In this configuration, as shown in FIG. 10, after the no-load voltage reaches the maximum, that is, reaches the overvoltage detection level,
When the operation is allowed so that the voltage of the capacitor C _G of the starting circuit 13A reaches the voltage level of the breakdown of Gap,,
This is a desirable operation that is easy to start.

[0070] Incidentally, the multiple precision voltage rectifier circuit 14 receives a boosted velocity impact on the capacitor C _G by the output voltage and the switching frequency and the output voltage is affected by the switching frequency and duty. That is, as the switching frequency of the output voltage is lower and the duty is larger, the speed of voltage rise increases, and the output of the multiple voltage rectifier circuit 14 increases in speed as the switching frequency increases.

Therefore, in the sixth embodiment, the duty is increased under the condition that the switching frequency is low until the load voltage reaches the predetermined value, and the output voltage is mainly boosted. When the switching voltage exceeds the predetermined value, the duty is reduced. , The switching frequency is increased, and the speed of boosting the output of the multiple voltage rectifier circuit 14 is increased. Thereby, the operation as shown in FIG. 10 can be realized, and the resonance phenomenon of the output can be suppressed.

FIG. 11 is a block diagram of a discharge lamp lighting device according to a seventh embodiment of the present invention, and FIG. 12 is an operation waveform diagram of the discharge lamp lighting device of FIG. Will be described.

The discharge lamp lighting device shown in FIG. 11 includes a load circuit 1, a DC power supply 2, and a DC-DC conversion circuit 3 in the same manner as the third embodiment, and differs from the third embodiment. An output control circuit 4C is provided as a point.

The output control circuit 4C is replaced with a DC control unit instead of the detection unit 41 and the adjustment circuit 47A of the third embodiment.
-Same as the output control circuit 4B of the third embodiment except that it has a detection unit 41A that further detects the input voltage of the DC conversion circuit 3 and an adjustment circuit 47B that further uses the detection result by the detection unit 41A. Is configured.

The discharge lamp lighting device of FIG. 11 mainly varies the duty among the switching frequency and the duty under the no-load condition by the current voltage. When a power supply having a relatively large voltage fluctuation range, such as a battery, is used for the DC power supply 2, it is difficult to fix the set value of the switching condition under no load. For example, if the adjustment is performed when a low voltage is input, switching stress or the like may be increased under a high voltage input condition, and the condition may be deviated from a condition for suppressing resonance. Further, if the adjustment is performed under the condition of a high input voltage, the rising of the voltage becomes slow due to insufficient output at the time of inputting the low voltage, and it takes time until the lamp is turned on.

Therefore, the adjusting circuit 47B changes the switching duty in accordance with the input voltage as shown in FIG. 12, and it is more preferable that the switching duty be inversely proportional to the input voltage.

Further, the adjusting circuit 47B limits the duty so as not to become larger than necessary by "max. Duty" shown in FIG. Then, based on this duty, the duty is switched or varied according to the output voltage, as in the above embodiment.

As described above, according to each of the above embodiments, when the load circuit 1 is in the no-load state, the resonance phenomenon at the output of the DC-DC conversion circuit in the intermittent switching state can be suppressed, You can get the boost speed,
The time until the discharge lamp 11 turns on can be shortened.

[0079]

As is apparent from the above, according to the first aspect of the present invention, a load circuit including a discharge lamp, a DC power supply, and a switching element are provided, and the switching element is turned on in accordance with a control signal. By turning on / off, DC power is taken from the DC power supply and converted into DC power of an output level corresponding to the control signal, and the converted DC power is output to the load circuit via an LC filter.
A C-DC conversion circuit; and an output control circuit that detects the output of the DC-DC conversion circuit and outputs the control signal using the detection result. When the detection result of the output voltage reaches a predetermined first voltage in a no-load state in which the output voltage of the conversion circuit is detected and the discharge lamp is turned off, the on / off control for the switching element is intermittently performed. And adjusting the detection result of the output voltage so as not to exceed the first voltage. As the detection result of the output voltage is higher, at least the on-duty for the switching element is reduced, so that the DC-DC conversion circuit Even if an LC filter is provided at the output of the above, it is possible to suppress a resonance phenomenon of the LC filter which may occur when the load circuit is in a no-load state.

According to a second aspect of the present invention, in the discharge lamp lighting device according to the first aspect, the output control circuit, in the no-load state, has a detection result of the output voltage lower than the first voltage. When the voltage exceeds two voltages, at least the on-duty for the switching element is reduced, so that the LC which may occur when the load circuit is in a no-load state without increasing the time until the discharge lamp is turned on.
The resonance phenomenon of the filter can be suppressed.

According to a third aspect of the present invention, in the discharge lamp lighting device according to the first aspect, in the no-load state, the output control circuit controls the switching element according to at least a detection result of the output voltage. The on-duty is changed continuously, and in this case also, the resonance phenomenon of the LC filter that can occur when the load circuit is in a no-load state can be suppressed.

According to the fourth aspect of the present invention, there is provided a load circuit including a discharge lamp, a DC power supply, and a switching element.
By turning on / off the switching element according to the control signal, the DC power is taken from the DC power supply and converted into DC power of an output level according to the control signal,
A DC-DC conversion circuit that outputs the converted DC power to the load circuit via an LC filter;
An output control circuit that detects the output of the C conversion circuit and outputs the control signal using the detection result. The output control circuit detects the output voltage of the DC-DC conversion circuit. In a no-load state in which the discharge lamp is off, when the detection result of the output voltage reaches a predetermined first voltage, on / off control of the switching element is performed intermittently, and the detection result of the output voltage is obtained. Is adjusted so as not to exceed the first voltage, and the higher the detection result of the output voltage is, the higher the switching frequency for at least the switching element is, so even if an LC filter is provided at the output of the DC-DC conversion circuit, It is possible to suppress a resonance phenomenon of the LC filter that may occur when the load circuit is in a no-load state.

According to a fifth aspect of the present invention, in the discharge lamp lighting device according to the fourth aspect, the output control circuit, in the no-load state, detects a detection result of the output voltage lower than the first voltage. When the voltage exceeds two voltages, at least the switching frequency for the switching element is increased. In this case as well, a resonance phenomenon of the LC filter which may occur when the load circuit is in a no-load state can be suppressed.

According to a sixth aspect of the present invention, in the discharge lamp lighting device according to the fourth aspect, in the no-load state, the output control circuit controls the switching element in accordance with at least the detection result of the output voltage. The switching frequency is continuously changed, and in this case, too,
It is possible to suppress a resonance phenomenon of the LC filter that may occur when the load circuit is in a no-load state.

According to the invention of claim 7, claims 1 to 1 are provided.
6. In the discharge lamp lighting device according to any one of 6, the output control circuit reduces the on-duty for the switching element as the detection result of the output voltage increases in the no-load state, and reduces the on-duty for the switching element. Since the switching frequency is increased, D
The rate of increase of the output voltage of the C-DC conversion circuit can be set finely.

According to an eighth aspect of the present invention, in the discharge lamp lighting device according to the seventh aspect, in the no-load state, the output control circuit detects that the detection result of the output voltage is lower than the first voltage. If the voltage exceeds two voltages, the on-duty for the switching element is reduced, and if the detection result of the output voltage exceeds a third voltage lower than the first voltage, the switching frequency for the switching element is increased. The resonance phenomenon of the LC filter which can occur when the load circuit is in a no-load state can be suppressed without increasing the time until the lamp is turned on.

According to the ninth aspect of the present invention, in the discharge lamp lighting device of the eighth aspect, the second voltage and the third
The voltages are at the same level, and also in this case, the resonance phenomenon of the LC filter that can occur when the load circuit is in a no-load state can be suppressed.

According to the tenth aspect, the eighth aspect is provided.
3. The discharge lamp lighting device according to claim 2, wherein the second voltage is higher than the third voltage, and in this case, too, it is possible to suppress a resonance phenomenon of the LC filter that may occur when the load circuit is in a no-load state. Can be.

According to the eleventh aspect, according to the eighth aspect,
3. The discharge lamp lighting device according to claim 1, wherein the third voltage is higher than the second voltage, and in this case, the resonance phenomenon of the LC filter which may occur when the load circuit is in a no-load state is also suppressed. Can be.

According to the twelfth aspect, the eighth aspect is provided.
In the discharge lamp lighting device according to the above, the output control circuit,
In the no-load state, the switching frequency and the on-duty for the switching element are continuously changed in accordance with the detection result of the output voltage.This also occurs when the load circuit is in the no-load state. The resonance phenomenon of the obtained LC filter can be suppressed.

According to the thirteenth aspect, according to the first aspect,
13. The discharge lamp lighting device according to any one of to 12, wherein in the no-load state, when the detection result of the output voltage is substantially at the level of the first voltage, the switching element performs one switching operation on the switching element. DC-DC
The circuit is set such that the time for consuming the energy amount equivalent to the energy amount output from the conversion circuit to the load circuit due to the circuit loss in the no-load state is sufficiently smaller than the resonance cycle of the LC filter. Therefore, it is possible to suppress a resonance phenomenon of the LC filter that may occur when the load circuit is in a no-load state.

According to the fourteenth aspect of the present invention, the first aspect is provided.
13. The discharge lamp lighting device according to any one of claims 13 to 13, further comprising a multiple voltage rectification circuit having an input connected to an alternating voltage portion in the DC-DC conversion circuit, wherein the output control circuit is in the no-load state. In such a manner that the output of the multiple voltage rectifier circuit does not exceed a predetermined fourth voltage until the detection result of the output voltage substantially reaches the level of the first voltage,
Since on / off control is performed on the switching element, it is possible to suppress a resonance phenomenon of the LC filter that may occur when the load circuit is in a no-load state, while securing a suitable startability.

According to the fifteenth aspect, the first aspect is provided.
5. The discharge lamp lighting device according to 4, wherein the output control circuit performs on / off control on the switching element at a switching frequency equal to or lower than a predetermined value until a detection result of the output voltage reaches the second voltage. Thereby, the increase in the output voltage of the multiple voltage rectifier circuit is suppressed, and when the detection result of the output voltage exceeds the second voltage, the switching frequency for the switching element is increased, whereby the multiple voltage rectifier circuit is increased. Since the output voltage of the LC filter is accelerated, it is possible to suppress a resonance phenomenon of the LC filter which may occur when the load circuit is in a no-load state while securing a suitable startability.

According to the sixteenth aspect of the present invention, the first aspect
15. In the discharge lamp lighting device according to any one of Items 15 to 15, the output control circuit changes the on-duty for the switching element with respect to the voltage of the DC power supply. In this case, the resonance phenomenon of the LC filter, which may occur in the case, can be suppressed.

According to the seventeenth aspect, in the first aspect,
6. The discharge lamp lighting device according to 6, wherein the output control circuit changes the on-duty for the switching element in inverse proportion to the voltage of the DC power supply. It is possible to suppress a resonance phenomenon of the LC filter that may occur in a certain case.

[Brief description of the drawings]

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

FIG. 2 is a configuration diagram of a discharge lamp lighting device according to a second embodiment of the present invention.

FIG. 3 is a configuration diagram of a discharge lamp lighting device according to a third embodiment of the present invention.

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

FIG. 5 is an operation waveform diagram of a discharge lamp lighting device according to a fourth embodiment of the present invention.

FIG. 6 is a diagram illustrating another example of control for continuously changing the duty of the switching element with respect to the output voltage of the DC-DC conversion circuit.

FIG. 7 is a diagram illustrating another control example in which the switching frequency of the switching element is continuously changed with respect to the output voltage of the DC-DC conversion circuit.

FIG. 8 is an operation waveform diagram of a discharge lamp lighting device according to a fifth embodiment of the present invention.

FIG. 9 is a configuration diagram of a discharge lamp lighting device according to a sixth embodiment of the present invention.

FIG. 10 is an operation waveform diagram of the discharge lamp lighting device of FIG. 9;

FIG. 11 is a configuration diagram of a discharge lamp lighting device according to a seventh embodiment of the present invention.

12 is an operation waveform diagram of the discharge lamp lighting device of FIG.

FIG. 13 is a configuration diagram of a conventional discharge lamp lighting device.

14 is an operation waveform diagram of the discharge lamp lighting device of FIG.

15 is an operation waveform diagram of the discharge lamp lighting device of FIG.

FIG. 16 is a configuration diagram of a conventional discharge lamp lighting device when an LC filter is provided at the output of the DC-DC conversion circuit.

FIG. 17 is a configuration diagram of a conventional discharge lamp lighting device when an LC filter is provided at the output of the DC-DC conversion circuit.

FIG. 18 is a DC-D of the discharge lamp lighting device of FIGS.
FIG. 7 is a diagram illustrating an example of a resonance phenomenon that can occur at the output of the C conversion circuit.

[Explanation of symbols]

 1, 1A load circuit 11 discharge lamp 14 multiple voltage rectification circuit 2 DC power supply 3 DC-DC conversion circuit SW3 switching element 4, 4A, 4B, 4C output control circuit

Claims (17)

[Claims] A load circuit including a discharge lamp, a DC power supply,
By having a switching element and turning on / off the switching element according to a control signal, it takes in DC power from the DC power supply, converts it into DC power of an output level according to the control signal, and converts the converted DC power. , L
DC-DC output to the load circuit via a C filter
A conversion circuit, and an output control circuit that detects the output of the DC-DC conversion circuit and outputs the control signal using the detection result. In a no-load state in which the output voltage is detected and the discharge lamp is turned off, when the detection result of the output voltage reaches a predetermined first voltage, on / off control for the switching element is performed intermittently. A discharge lamp lighting device, wherein the detection result of the output voltage is adjusted so as not to exceed the first voltage, and the on-duty for at least the switching element is reduced as the detection result of the output voltage is higher. 2. The output control circuit according to claim 1, wherein, in the no-load state, when a detection result of the output voltage exceeds a second voltage lower than the first voltage, at least an on-duty for the switching element is reduced. The discharge lamp lighting device according to claim 1, wherein 3. The discharge control according to claim 1, wherein the output control circuit continuously changes an on-duty for the switching element in accordance with at least a detection result of the output voltage in the no-load state. Lighting device. 4. A load circuit including a discharge lamp, a DC power supply,
By having a switching element and turning on / off the switching element according to a control signal, it takes in DC power from the DC power supply, converts it into DC power of an output level according to the control signal, and converts the converted DC power. , L
DC-DC output to the load circuit via a C filter
A conversion circuit, and an output control circuit that detects the output of the DC-DC conversion circuit and outputs the control signal using the detection result. In a no-load state in which the output voltage is detected and the discharge lamp is turned off, when the detection result of the output voltage reaches a predetermined first voltage, on / off control for the switching element is performed intermittently. A discharge lamp lighting device, wherein the detection result of the output voltage does not exceed the first voltage, and the higher the detection result of the output voltage, the higher the switching frequency for at least the switching element. 5. The output control circuit increases a switching frequency of at least the switching element when a detection result of the output voltage exceeds a second voltage lower than the first voltage in the no-load state. The discharge lamp lighting device according to claim 4, wherein 6. The discharge control according to claim 4, wherein said output control circuit continuously changes a switching frequency for said switching element in accordance with at least a detection result of said output voltage in said no-load state. Lighting device. 7. The output control circuit, in the no-load state, decreases an on-duty for the switching element and increases a switching frequency for the switching element as the detection result of the output voltage increases. The discharge lamp lighting device according to claim 1. 8. The output control circuit, when the detection result of the output voltage exceeds a second voltage lower than the first voltage in the no-load state, decreases an on-duty for the switching element, and 8. The discharge lamp lighting device according to claim 7, wherein when the detection result exceeds a third voltage lower than the first voltage, the switching frequency for the switching element is increased. 9. The discharge lamp lighting device according to claim 8, wherein the second voltage and the third voltage are at the same level. 10. The discharge lamp lighting device according to claim 8, wherein the second voltage is at a higher level than the third voltage. 11. The discharge lamp lighting device according to claim 8, wherein the third voltage is at a higher level than the second voltage. 12. The output control circuit according to claim 8, wherein in the no-load state, a switching frequency and an on-duty for the switching element are continuously changed according to a detection result of the output voltage. The discharge lamp lighting device as described in the above. 13. In the no-load state, when the detection result of the output voltage is substantially at the level of the first voltage,
In one switching operation of the switching element, the time required for consuming the same amount of energy as the amount of energy output from the DC-DC conversion circuit to the load circuit due to the circuit loss in the no-load state is obtained by the LC filter. The discharge lamp lighting device according to any one of claims 1 to 12, wherein the circuit is set to be sufficiently smaller than the resonance cycle of (1). 14. A multi-voltage rectifier circuit having an input connected to an alternating voltage portion in the DC-DC conversion circuit, wherein the output control circuit detects a detection result of the output voltage in the no-load state. The on / off control of the switching element is performed so that the output of the multiple voltage rectifier circuit does not exceed a predetermined fourth voltage until the level substantially reaches the level of the first voltage. 14. The discharge lamp lighting device according to any one of 1 to 13. 15. The output control circuit performs on / off control on the switching element at a switching frequency equal to or lower than a predetermined value until a detection result of the output voltage reaches the second voltage, thereby controlling the multiplicity. The output voltage of the multiple voltage rectifier circuit is suppressed by suppressing an increase in the output voltage of the multiple voltage rectifier circuit, and when the detection result of the output voltage exceeds the second voltage, the switching frequency for the switching element is increased. The discharge lamp lighting device according to claim 14, wherein the ascending is accelerated. 16. The discharge lamp lighting device according to claim 1, wherein the output control circuit changes an on-duty for the switching element with respect to a voltage of the DC power supply. 17. The discharge lamp lighting device according to claim 16, wherein the output control circuit changes the on-duty for the switching element in inverse proportion to the voltage of the DC power supply.