JPH10257758A - Dc-dc converter, high voltage discharge lamp lighting apparatus and lighting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a DC-DC converter suitable for short-arc high voltage discharge lamp which assures high circuit efficiency, low level propagation noise and radiation noise and reduction in size by sequentially operating a main circuit connecting the input end to a DC power supply and a switching means of each chopper. SOLUTION: A first and a second choppers 2A, 2B are connected in parallel through the input end and output end to form a main circuit. The first and second choppers 2A, 2B are respectively provided with a rectifying power supply, a switching means, a flywheel diode, an inductor and a smoothing capacitor. A control means 6 sequentially operates the switching means of each chopper 2A, 2B and controls the means as it were single chopper viewed from the output end of the main circuit. That is, switching operation of the choppers 2A, 2B is deviated electrically by 180 degrees and each chopper 2A, 2B is operated with the operation frequency viewed from the output end.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC-DC converter, a high pressure discharge lamp lighting device and a lighting device using the same.

[0002]

2. Description of the Related Art Small high-pressure discharge lamps have been used as light sources in projection television receivers and overhead projectors. Initially, the high pressure discharge lamps used for this type of application were lit with alternating current.

However, when the high-pressure discharge lamp is lit by direct current, the illuminance on the projection surface can be increased, so that the direct-current lighting is increasing recently. The initial high-pressure discharge lamp of this type had a distance between the electrodes of 5 to 10 mm.

[0004] In order to perform DC lighting of such a high-pressure discharge lamp, a step-down chopper is used because the discharge lamp is of a short arc type and therefore has a low lamp voltage.

FIG. 11 is a circuit diagram showing a conventional high pressure discharge lamp lighting device having a step-down chopper as a main circuit.

In the drawing, 111 is a DC power supply, 112 is switching means, 113 is control means, 114 is a flywheel diode, 115 is an inductor, 116 is a smoothing capacitor, 117 is a starting circuit, 118 is a high-pressure discharge lamp, and 119 is a main unit. Circuit.

The switching means 112 uses a transistor or the like. The main circuit 1 composed of a step-down chopper includes the switching means 112, a flywheel diode 114, an inductor 115 and a smoothing capacitor 116.
19.

[0008] The control means 113 comprises the switching means 11
2 is turned on and off at a predetermined cycle and duty,
It acts to supply constant power to the high-pressure discharge lamp 118.

FIG. 12 is a waveform diagram of the control signal voltage and the output current in FIG.

In the figure, Vg is a control signal voltage, and I is an output current.

Recently, a high-pressure discharge lamp having a distance between electrodes of 4 mm or less has become mainstream in order to improve the light-collecting efficiency of an optical system. There is a strong demand for higher efficiency, lower noise, and smaller size.

[0012]

However, as the distance between the electrodes becomes smaller, the lamp voltage necessarily decreases. In order to supply the same power to the high-pressure discharge lamp, it is necessary to increase the lamp current as the distance between the electrodes becomes shorter. The increase in lamp current leads to a decrease in circuit efficiency, an increase in propagation noise and radiation noise, and an increase in the size of the device.

First, the circuit efficiency will be described.

The loss in the chopper is mainly due to switching loss. The switching loss occurs with the switching of the switching means, and is proportional to the current flowing through the switching means. That is, as the lamp current increases, the circuit loss increases, in other words, the circuit efficiency decreases. In addition, an increase in switching loss in the switching means causes an increase in the size of the switching means and / or an increase in the size of the heat dissipation device. This means an increase in the size of the device.

Further, this type of high-pressure discharge lamp has a lamp voltage of about 200 W in power consumption and 30 to 6
It is as low as 0V. On the other hand, the no-load open voltage is 240 to 400 V as described above, and in the case of PWM control,
The on-duty ratio at the time of stable lighting becomes small, so that the circuit efficiency is poor. In particular, when the switching speed is suppressed to reduce the propagation noise and the radiation noise, the circuit efficiency is significantly deteriorated.

Next, propagation noise and radiation noise will be described.

In the step-down chopper, when the switching condition is constant, the switching noise increases as the input voltage and the output current increase. Therefore, the output current, that is, the lamp current increases with the decrease in the inter-electrode distance, so that the propagation noise and the radiation noise mainly due to the switching noise increase.

Finally, the enlargement of the apparatus will be described.

The enlargement of the device is mainly due to the enlargement of the winding parts. In a general lighting device for a metal halide lamp having a no-load open-circuit voltage of 240 to 400 V, the rated output current is 4
In the case of about A, the inductor of the step-down chopper is EI-3
Although about three cores can be used, when the output current is 6 A or more, a core of EI-50 or more is required.

The present invention relates to a DC-DC converter suitable for a short arc type high pressure discharge lamp, which has high circuit efficiency, reduces propagation noise and radiation noise, and can be miniaturized, and a high pressure discharge lamp using the same. It is an object to provide a lighting device and a lighting device.

[0021]

According to the first aspect of the present invention, the DC-
The DC converter comprises: a DC power supply; a main circuit having a plurality of choppers each including a switching means, a flywheel diode, an inductor and a smoothing capacitor connected in parallel, and an input terminal connected to the DC power supply; and a switching means for each chopper. Control means for operating the main circuit as a single chopper as viewed from the output end by sequentially operating.

In the present invention and each of the following inventions, definitions and technical meanings of terms are as follows unless otherwise specified.

The DC-DC converter may be any one of a step-down type chopper, a step-up type chopper, a reverse polarity type chopper, etc., as long as it is a chopper provided with a switching means, a flywheel diode, an inductor and a smoothing capacitor.

The DC power supply may be any of a battery power supply, a generator power supply and a rectified power supply. In the case of a rectified power supply, whether or not smoothing is performed does not matter, but since there is a smoothing action by a chopper, smoothing need not be performed.

The switching means may be any type such as a transistor as long as the switching can be controlled by the control means.

The flywheel diode is connected so as to allow a current caused by the back electromotive force of the inductor to flow.

The inductor stores electromagnetic energy when the switching means is turned on, and discharges it when the switching means is turned off.

The smoothing capacitor smoothes the output voltage.

The connection positions of the above-mentioned switching means, flywheel diode and inductor vary depending on the type of chopper. In the step-down type, switching means and an inductor are connected in series between an input terminal and an output terminal. In the boost type, an inductor and a flywheel diode are similarly connected in series. Further, in the reverse polarity type, the switching means and the flywheel diode are connected in series. The flywheel diode is connected in relation to the inductor so that a current due to the back electromotive force of the inductor flows to the load side.

A plurality of choppers are connected in parallel.
In this case, some components of the chopper, for example, a smoothing capacitor may be shared by a plurality of choppers.

The control means supplies a control signal to the switching means of the chopper to control on / off thereof. In the present invention, the control means further controls the switching means of the plurality of choppers to operate sequentially. Further, a constant voltage adjusting function can be provided by changing the on-duty of the switching means in accordance with the input voltage or the output voltage of the chopper.
Still further, by changing the on-duty of the switching means in accordance with the input current or the output current, a constant current adjusting function can be provided. Therefore, the constant power control can be performed by controlling both the voltage and the current.

Although the load of the DC-DC converter is preferably a high-pressure discharge lamp, the present invention is not limited to this.

Thus, in the present invention, since a plurality of choppers are sequentially operated, when viewed from the output end, it acts as if a single chopper operates at a predetermined frequency. Therefore, each chopper will operate at a fraction of the frequency of the chopper. In addition, the current handled by each chopper is a fraction of that of the chopper.

First, the switching loss will be described.

The switching loss is proportional to the current flowing through the chopper as described above.
As described above, the current handled by each chopper is a fraction of that of the chopper, so that the switching loss is also a fraction of that of the chopper. Further, the chance of switching loss occurring in each chopper is reduced to a fraction of that of the chopper as the operating frequency decreases as described above.

Therefore, the switching loss that occurs in each chopper is one square of the number of choppers.
For example, in the case where two choppers are used as described above, the switching loss of each chopper is ４. As a whole, the switching loss of the DC-DC converter is half that of a single chopper.
Becomes Similarly, if three choppers are used, it can be seen that the switching loss is one third. However, as the number of choppers increases, the conduction loss due to the resistance of the flywheel diode increases, but the circuit efficiency is greatly affected by the switching loss. I do.

Further, since the operating frequency of each chopper is a fraction of that of the chopper as described above, the ON time of the switching means in each chopper is several times that of the chopper. Therefore, for example, even if the load is a short arc high-pressure discharge lamp having a low lamp voltage and the on-duty is small, deterioration of circuit efficiency is prevented.

Next, propagation noise and radiation noise will be described.

As described above, the main factor of the propagation noise and the radiation noise is the switching noise, and the switching noise increases and decreases in proportion to the current flowing through the switching means. Therefore, the propagation noise and the radiation noise greatly increase as the current decreases. To decrease.

Finally, the size of the apparatus will be described.

The cross-sectional area of the winding of the inductor, which is a winding component that greatly affects the size of the device, is proportional to the average current of the chopper. As can be understood from the above, since the average current is a fraction of that of the chopper, a thin conductive wire can be used as the winding, which contributes to downsizing of the inductor. Further, as described above, as the circuit loss and the noise are reduced, the switching means and the heat radiating device thereof can be downsized, so that the device can be downsized as a whole.

In a single chopper, a plurality of switching means may be connected in parallel to sequentially operate the switching means. However, the present invention has the following advantages as compared with this case.

Since the switching frequency of each chopper is a fraction of that of the chopper, there is room for malfunction such as intermittent oscillation that may occur when the lamp voltage is low.

Since the switching on of the switching means starts from zero current, little switching loss occurs. Further, since the peak current at the time of switching off is small, the maximum switching loss is also small.

Since the current flowing through the inductor is a fraction of that of the chopper, a thin winding can be used irrespective of the inductance, and the size of components can be reduced.

If the operating frequency is further increased by utilizing the margin when the lamp voltage is low, the size can be further reduced.

A DC-DC converter according to a second aspect of the present invention comprises a DC power supply and a plurality of choppers each including a switching means, a flywheel diode, an inductor and a smoothing capacitor, connected in parallel by sharing a smoothing capacitor. A main circuit having an end connected to a DC power supply; and control means for operating the switching means of each chopper so that the main circuit operates as a single chopper as viewed from the output end. It is characterized by.

According to the present invention, when a plurality of choppers are connected in parallel, a smoothing capacitor is commonly used for each chopper. The ripple current flowing through the smoothing capacitor is
The currents flowing through the respective choppers are added so as to cancel each other. Other operations are the same as those of the first aspect.

The DC-DC converter according to the third aspect of the present invention is the DC-DC converter according to the first or second aspect, wherein the control means is configured such that the current flowing through the inductor of each chopper is intermittent and the output current is continuous. It is characterized in that the main circuit is controlled to have a waveform.

According to the present invention, in each chopper, even if the current flowing through the inductor is intermittent, the combined output current is continuous. The period in which the current flows through the flywheel diode in the other chopper in which the switching means was turned on before that overlaps, and the current value flowing through the switching means at the moment of switching can be reduced. Further, switching loss can be reduced.

The high pressure discharge lamp lighting device according to the fourth aspect of the present invention supplies an output to the high pressure discharge lamp.
And a starting device that supplies a starting voltage to the high-pressure discharge lamp.

The DC-DC converter according to claims 1 to 3 has a small switching loss and a small amount of propagation noise and radiation noise. Therefore, it is particularly suitable for lighting a short arc type high pressure discharge lamp having a low lamp voltage and a large lamp current. It is. In the case of the short arc type, the distance between the electrodes is generally 6
mm or less, preferably 4 mm or less. The short arc type high pressure discharge lamp can easily exhibit optical performance by being provided with a reflecting mirror as necessary.

The high pressure discharge lamp used in the present invention is particularly effective when it is a short arc type metal halide lamp. When the discharge medium has the following configuration, the metal halide lamp for projection provides preferable results in terms of required luminous characteristics, that is, luminous efficiency, correlated color temperature, chromaticity, and color rendering. That is, dysprosium Dy, cesium Cs, and neodymium Nd are mainly used as luminescent metals, and thallium Tl and / or tin S
n is added as a sub-component as required, and an appropriate amount of iodine I and / or bromine Br is sealed with mercury and a rare gas for these components.

However, the present invention has an effect even when a high pressure discharge lamp which is not a short arc type is turned on, and is not limited to a short arc type high pressure discharge lamp.

If the high-pressure discharge lamp is connected directly to the output terminal of the DC-DC converter, the high-pressure discharge lamp can be turned on in direct current. In this case, if the chopper is connected in series to the high-pressure discharge lamp, the inductor can also be used as a ballast element of the high-pressure discharge lamp. However, if necessary, a ballast element can be separately inserted on the input side or the output side of the chopper. Also, the ballast element can be inserted on the AC or DC side of the circuit.

Further, when the high-pressure discharge lamp is to be turned on by alternating current, the output of the DC-DC converter may be converted to an alternating output by a polarity conversion means such as an inverter and then supplied to the high-pressure discharge lamp.

Immediately after the start of the high-pressure discharge lamp and during the rise of the luminous flux, the current flowing through the inductor of each chopper is increased as a continuous waveform, and the current is discontinuous during stable lighting, but the output current is changed to a continuous waveform. By doing so, it is permissible to control so as to reduce the switching loss. Even with a high-pressure discharge lamp having a large lamp voltage fluctuation range, such as a metal halide lamp, a good effect can be obtained during stable lighting by configuring as described above.

According to a fifth aspect of the present invention, there is provided the high pressure discharge lamp lighting device according to the fourth aspect.
A current detecting means for detecting an input current or a lamp current of the high pressure discharge lamp; a voltage detecting means for detecting an input voltage or a lamp voltage of the high pressure discharge lamp; The switching means is controlled to supply predetermined power to the high-pressure discharge lamp according to the current and the input voltage or the lamp voltage of the high-pressure discharge lamp.

In the present invention, desired power can be supplied to the high-pressure discharge lamp by controlling the switching means according to the DC power supply condition or the load condition of the high-pressure discharge lamp. The desired power may be a constant power or any other desired power.

According to a sixth aspect of the present invention, in the high pressure discharge lamp lighting device according to the fourth aspect,
A peak current detecting means for detecting a peak current in one cycle of a current flowing through the switching means; and a voltage detecting means for detecting a lamp voltage of the high pressure discharge lamp;
The control means calculates the outputs of the peak current detection means and the voltage detection means, and turns on and off the switching means until the calculation result exceeds a predetermined value, but turns off the switching means when the calculation result exceeds the predetermined value; It is characterized by:

In the present invention, the lamp current is monitored during the lighting by calculating the lamp voltage of the high-pressure discharge lamp and the peak current of the current flowing through the switching means. Then, the switching means is turned off to suppress an increase in the lamp current. Therefore, it is possible to correct a decrease in output due to an increase in circuit loss due to an increase in lamp current.

According to a seventh aspect of the present invention, in the high pressure discharge lamp lighting device according to any one of the fourth to sixth aspects, the control means controls the characteristic of the power supplied to the high pressure discharge lamp to the inductor of the chopper. When the flowing current is discontinuous, a constant power characteristic is set. When the current flowing through the inductor is continuous, the switching means is controlled so that the characteristic becomes closer to the constant current characteristic as the on-duty becomes smaller.

In the present invention, the constant power characteristic does not mean only a complete constant power characteristic, but also includes a similar power characteristic which may be almost constant power characteristic.

The present invention provides desirable power characteristics when the high pressure discharge lamp is a metal halide lamp.

An eighth aspect of the present invention is directed to the high pressure discharge lamp lighting device according to any one of the fourth to seventh aspects, further comprising a high pressure discharge lamp.

The present invention includes a high-pressure discharge lamp as a component of a high-pressure discharge lamp lighting device.

The high-pressure discharge lamp may be integral with or common to the DC-DC converter, or may be separated if necessary.

According to a ninth aspect of the present invention, there is provided a lighting device, comprising: a lighting device main body; and the high pressure discharge lamp lighting device according to the eighth aspect supported by the lighting device main body.

The lighting device of the present invention is applicable to all devices that use a high-pressure discharge lamp for some lighting purpose. For example, the present invention can be applied to a lighting fixture, a display device, a signal lamp device, an image projection device, and the like. The lighting fixtures include various indoor lighting fixtures and various outdoor lighting fixtures. As the image projection device, a liquid crystal projector,
It can be applied to an overhead projector and the like.

[0070]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing a DC-DC converter and a high-pressure discharge lamp lighting device according to a first embodiment of the present invention.

In the figure, 1 is an AC power supply, 2A is a first chopper, 2B is a second chopper, 3 is a main circuit, 4 is a starting circuit, 5 is a high-pressure discharge lamp, and 6 is control means.

AC power supply 1 is a commercial AC power supply.

The first and second choppers 2A and 2B
Its input and output are both connected in parallel,
These constitute the main circuit 3. And the first and second
Choppers 2A and 2B each include a rectified power supply, switching means, a flywheel diode, an inductor, and a smoothing capacitor.

The starting circuit 4 is of a known type.

The high-pressure discharge lamp 5 is a short arc type metal halide lamp.

The control means 6 controls the switching means of each chopper sequentially so as to control it as a single chopper when viewed from the output terminal of the main circuit. That is, the switching of each chopper is electrically shifted by 180 °, and each chopper is operated at an operating frequency that is half the operating frequency when viewed from the output end.

FIG. 2 is a circuit diagram showing a DC-DC converter and a high-pressure discharge lamp lighting device according to a second embodiment of the present invention.

This embodiment differs from the embodiment of FIG. 1 in that the smoothing capacitor 2a of each chopper is shared by using a single electrolytic capacitor. Therefore, the same parts as those in FIG.

FIG. 3 is a circuit diagram showing a third embodiment of the DC-DC converter and the high pressure discharge lamp lighting device of the present invention.

In the figure, the same parts as those in FIG.

This embodiment specifically shows the circuit configuration of the chopper. That is, the first and second choppers 2A and 2B are respectively connected to a series circuit of the switching means 2b and the flywheel diode 2c connected between both poles of the DC power supply 7, and an inductor 2d at a connection point of the switching means and the flywheel diode 2c.
And a smoothing capacitor 2a connected between the other end of the inductor 2d and a connection point between the flywheel diode 2c and the DC power supply 7.

FIG. 4 is a voltage / current waveform diagram of each part in FIG.

In the figure, Va and Vb are control signal voltages,
Ia and Ib are inductor currents, and Ic is a smoothing capacitor input current.

The control signal voltages Va and Vb are output from the control means 6, but are 180 ° out of phase. The control signal voltage Va is applied to the switching means 2 of the first chopper 2A.
b is applied to the control pole. The control signal voltage Va is applied to the control pole of the switching means 2b of the second chopper 2B.

The inductor currents Ia and Ib are currents flowing through the inductor 2d. The inductor current Ia is
Flows through the inductor 2d of the chopper 2A. The inductor current Ib flows through the inductor 2d of the second chopper 2B.

The smoothing current input current Ic is a current flowing into the smoothing capacitor 2a. This smoothing capacitor input current Ic corresponds to the sum of the inductor currents 2d of the first and second choppers 2A and 2B.

As is clear from FIG. 4, the inductor currents Ia and Ib rise from zero when the switching means 2b is on, and flow through the flywheel diode 2c by the back electromotive force of the inductor 2d to turn off when the switching means 2b is off. Then, the zero state is maintained until the switching means 2b is turned on. Therefore, the inductor currents Ia and Ib have discontinuous waveforms. However, during the fall period of the current, the switching means 2b of the other chopper is turned on, and the inductor current rises. Both inductor currents Ia and Ib are added to form a smoothing capacitor input current Ic. Therefore, the smoothing capacitor input current Ic has a continuous waveform.

The high-pressure discharge lamp 5 is supplied with a smoothing capacitor input current Ic, which is lit by DC.

FIG. 5 is a circuit diagram showing a fourth embodiment of the DC-DC converter and the high pressure discharge lamp lighting device of the present invention.

In the figure, the same parts as those in FIG. 3 are denoted by the same reference numerals, and description thereof will be omitted.

This embodiment is different from the first embodiment in that a lamp voltage detecting means 8 and a lamp current detecting means 9 are provided. That is, the control means 6 controls each of the choppers 2A, 2B according to the output of the lamp voltage detection means 8 and the lamp current detection means 9.
By controlling the switching of each of the switching means 2b, a predetermined electric power is supplied to the high-pressure discharge lamp 5.

FIG. 6 is a circuit diagram showing a fifth embodiment of the DC-DC converter and the high pressure discharge lamp lighting device of the present invention.

In the figure, the same parts as those in FIG.

This embodiment is different from the first embodiment in that input voltage detecting means 10 and input current detecting means 11 are provided. That is, the control means 6 controls each of the choppers 2A, 2B according to the outputs of the input voltage detection means 10 and the input current detection means 11.
By controlling the switching of each of the switching means 2b, a predetermined electric power is supplied to the high-pressure discharge lamp 5.

FIG. 7 is a circuit diagram showing a DC-DC converter and a high-pressure discharge lamp lighting device according to a sixth embodiment of the present invention.

In the figure, the same parts as those in FIG.

The present embodiment differs from the first embodiment in that switching current detecting means 12a and 12b are provided for each of the choppers 2A and 2B. That is, the control unit 6 is configured to supply predetermined power to the high-pressure discharge lamp 5 by controlling the switching of the switching unit 2b according to the outputs of the switching current detection units 12a and 12b.

FIG. 8 is a circuit diagram showing a seventh embodiment of the DC-DC converter and the high pressure discharge lamp lighting device of the present invention.

In the figure, the same parts as those in FIG. 7 are denoted by the same reference numerals, and description thereof will be omitted.

In the present embodiment, peak current detecting means 12a 'and 12b' for detecting a one-cycle peak current of a switching current for each of the choppers 2A and 2B, and a lamp voltage detecting means for detecting a lamp voltage of the high-pressure discharge lamp 5 are provided. The difference is that a means 8 is added. That is, the control means 6 calculates the output of the peak current detection means 12a ', 12b' and the lamp voltage detection means 8 by the control means 6, and controls the switching of the switching means 2b in accordance with the calculation result, thereby providing a high voltage. It is configured to supply a predetermined power to the discharge lamp 5.

FIG. 9 is a sectional view showing an eighth embodiment of the high pressure discharge lamp lighting device according to the present invention.

In the figure, 5 is a high-pressure discharge lamp, 13 is a lighting device, and 14 is a reflector.

The high-pressure discharge lamp 5 has a discharge vessel 5a made of ceramics, and an anode 5b is provided at both ends of the discharge vessel 5a.
And the cathode 5c. 5d is a base fixed to one end of the discharge vessel 5a, 5e is an anode lead wire protruding from the base 5d, 5f is a cathode lead, and 5g is a power supply line.
The discharge vessel 5a is filled with a luminescent metal halide, a rare gas, and mercury as a discharge medium.

The lighting device 13 includes the main circuit 3 and the starting circuit 4 in FIG.

The reflecting mirror 14 is formed by glass molding. The reflecting mirror 14 has a neck portion 4a at the top, and the reflecting mirror main portion 1
4b is formed in a spheroidal surface, and has a visible light reflection
An infrared transmissive multilayer interference film 14c is formed. Further, a through hole 14d is formed in the reflecting mirror main portion 14b. The high-pressure discharge lamp 5 has its base 5 d fixed in the neck portion 14 a via the base cement 15. Further, the power supply line 5g passes through the through hole 14d of the reflecting mirror 14 and is led out to the rear side of the reflecting mirror 14 so that the lighting device 13
It is connected to the.

FIG. 10 is a conceptual diagram showing an image projection device which is an embodiment of the illumination device of the present invention.

In the figure, the same parts as those in FIG. 9 are denoted by the same reference numerals, and description thereof will be omitted. 15 is a liquid crystal display means, 16 is an image control means, 17 is an optical system, 18 is a main body case, 19
Is the screen.

The liquid crystal display means 15 displays an image to be projected by liquid crystal, and irradiates illumination light emitted from the high-pressure discharge lamp 5 and condensed by the reflecting mirror 14 from the back thereof.

The image control means 16 drives and controls the liquid crystal display means 15, and can have a television receiving function if necessary.

The optical system 17 condenses the light transmitted through the liquid crystal display means 15 and projects it on a screen 19.

The main body case 18 houses the above-described components, and further houses other necessary control mechanisms.

[0113]

According to each of the first to third aspects of the present invention, a plurality of choppers are connected in parallel, and each switching means is sequentially operated to operate as a single chopper when viewed from the output end. , A DC-DC converter with high circuit efficiency and low propagation noise and radiation noise can be provided.

According to the second aspect of the present invention, a DC-DC converter with a reduced number of components can be provided by additionally using a smoothing capacitor for each chopper.

According to the third aspect of the present invention, in addition, by making the current flowing through the inductor of each chopper intermittent and making the output current continuous, it is possible to control the load with a constant power. A DC converter can be provided.

According to each of the fourth to eighth aspects of the present invention, it is possible to provide a high pressure discharge lamp lighting device which has the effects of the first to third aspects and is particularly suitable for a short arc type high pressure discharge lamp.

According to the fifth aspect of the present invention, it is possible to provide a high-pressure discharge lamp lighting device for supplying predetermined power to the high-pressure discharge lamp according to the input current or the lamp current and the input voltage or the lamp voltage.

According to the sixth aspect of the present invention, in addition, the switching means is controlled in accordance with the peak current and the lamp voltage in one cycle of the current flowing through the switching means, so that the high pressure discharge which suppresses an increase in switching loss is suppressed. A lamp lighting device can be provided.

According to the seventh aspect of the present invention, in addition, when the current flowing through the inductor of each chopper is discontinuous, the constant power characteristic is obtained. By using power characteristics, it is possible to provide an optimal high pressure discharge lamp lighting device when the high pressure discharge lamp is a metal halide lamp.

According to the eighth aspect of the present invention, it is possible to provide a high pressure discharge lamp lighting device including a high pressure discharge lamp.

According to the ninth aspect of the present invention, it is possible to provide a lighting device having the effects of the first to eighth aspects.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a first embodiment of a DC-DC converter and a high pressure discharge lamp lighting device of the present invention.

FIG. 2 is a circuit diagram showing a DC-DC converter and a high-pressure discharge lamp lighting device according to a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing a third embodiment of the DC-DC converter and the high pressure discharge lamp lighting device of the present invention.

FIG. 4 is a diagram showing voltage / current waveforms at various parts in FIG.

FIG. 5 is a circuit diagram showing a fourth embodiment of the DC-DC converter and the high pressure discharge lamp lighting device of the present invention.

FIG. 6 is a circuit diagram showing a fifth embodiment of the DC-DC converter and the high pressure discharge lamp lighting device of the present invention.

FIG. 7 is a circuit diagram showing a sixth embodiment of the DC-DC converter and the high pressure discharge lamp lighting device of the present invention.

FIG. 8 is a circuit diagram showing a seventh embodiment of the DC-DC converter and the high pressure discharge lamp lighting device of the present invention.

FIG. 9 is a cross-sectional view showing an eighth embodiment of the high pressure discharge lamp lighting device of the present invention.

FIG. 10 is a conceptual diagram showing an image projection device which is an embodiment of the illumination device of the present invention.

FIG. 11 is a circuit diagram showing a conventional high pressure discharge lamp lighting device having a step-down chopper as a main circuit.

FIG. 12 is a waveform chart of a control signal voltage and an output current in FIG. 11;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... AC power supply 2A ... First chopper 2B ... Second chopper 2a ... Smoothing capacitor 3 ... Main circuit 4 ... Starting circuit 5 ... High pressure discharge lamp 6 ... Control means

Claims (9)

[Claims] And a main circuit in which a plurality of choppers each having a switching means, a flywheel diode, an inductor, and a smoothing capacitor are connected in parallel, and an input terminal is connected to the DC power supply; and a switching means for each chopper. Control means for operating the main circuit as a single chopper when viewed from the output end by sequentially operating the DC-DC converter. A main circuit having a plurality of choppers each including a switching means, a flywheel diode, an inductor, and a smoothing capacitor, connected in parallel by sharing a smoothing capacitor, and having an input terminal connected to the DC power supply; ;
Control means for operating the switching means of each chopper sequentially so that the main circuit is a single chopper as viewed from the output end. 3. The control circuit according to claim 1, wherein the control circuit controls the main circuit so that the current flowing through the inductor of each chopper is intermittent and the output current has a continuous waveform.
A DC-DC converter as described. 4. The system according to claim 1, wherein the output is supplied to a high-pressure discharge lamp.
A DC-DC converter according to any one of claims 1 to 3, and
And a starting device for supplying a starting voltage to the high-pressure discharge lamp. 5. A control device comprising: an input current or a lamp current of a high pressure discharge lamp; and a voltage detection unit for detecting an input voltage or a lamp voltage of a high pressure discharge lamp. 5. The high-pressure discharge lamp according to claim 4, wherein the switching means is controlled so as to supply a predetermined power to the high-pressure discharge lamp according to a lamp current and an input voltage of the high-pressure discharge lamp or a lamp voltage of the high-pressure discharge lamp. Lighting device. 6. A peak current detecting means for detecting a peak current in one cycle of a current flowing through the switching means;
Voltage detecting means for detecting the lamp voltage of the high-pressure discharge lamp; the control means calculates the outputs of the peak current detecting means and the voltage detecting means, and turns on the switching means until the calculated result exceeds a predetermined value. 5. The high pressure discharge lamp lighting device according to claim 4, wherein the switching means is turned off when a predetermined value is exceeded. 7. The control means sets the characteristic of the power supplied to the high-pressure discharge lamp to a constant power characteristic when the current flowing through the inductor of the chopper is discontinuous, and sets the on-duty characteristic when the current flowing through the inductor is continuous. 7. The high pressure discharge lamp lighting device according to claim 4, wherein the switching means is controlled so that the characteristic becomes closer to the constant current characteristic as is smaller. 8. The high pressure discharge lamp lighting device according to claim 4, further comprising a high pressure discharge lamp. 9. A lighting device comprising: a lighting device main body; and the high pressure discharge lamp lighting device according to claim 8 supported by the lighting device main body.