JPH1052059A - Power supply unit, discharge lamp lighting device, and illuminating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide sufficient protection for a switching means and an output circuit at the time when electric current is inputted or over-voltage is generated such as surging. SOLUTION: An output control circuit 23 and a comparator 28 control the on-duty ratio of switching means 21, 22 on charging side and discharging side, so that the peak value of detected results of the current detection circuit 27 may approach a constant value, if the current value in a current detection circuit 27 indicates a prescribed value or lower than it. If the current value which the current detection circuit 27 indicates exceeds the prescribed value, the on-duty ratio of the switching means 21 on charging side is set lower so that the current value may be lower than the cast at the prescribed value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply, a discharge lamp lighting device, and a lighting device for obtaining a high frequency voltage by using a switching means.

[0002]

2. Description of the Related Art Conventionally, as a discharge lamp lighting device for obtaining a high frequency voltage from a non-smooth DC voltage by using a switching means, a discharge lamp lighting device described in Japanese Patent Application Laid-Open No. 8-98555 has been used. Devices capable of improving the input power factor and reducing the distortion of the input current have been developed.

FIG. 12 is a circuit diagram showing an example of a conventional discharge lamp lighting device capable of improving the input power factor from such an AC power supply and reducing the distortion of the input current.

In FIG. 12, one output terminal of an AC power supply 51 such as a commercial AC power supply is connected to one input terminal of a full-wave rectifier by a rectifier circuit 52 such as a diode bridge via a choke coil L51. The other output terminal is connected to the other input terminal of the rectifier circuit 52 via the choke coil L52. The choke coil L51 and the choke coil L52 are magnetically coupled.

[0005] A capacitor C51 is connected between the input terminals of the rectifier circuit 52.

A positive output terminal of the rectifier circuit 52 is connected to a positive input terminal of the inverter 60. The output terminal on the negative side of the rectifier circuit 52 is connected to the input terminal on the negative side of the inverter 60.

The inverter 60 includes switching means 61 such as a MOSFET on the discharging side, switching means 62 such as a MOSFET on the charging side, a diode D51 and an output control circuit 63, a first capacitor C11 such as an electrolytic capacitor, and a second capacitor. C12 and an inductor 64 such as an inverter transformer.

Hereinafter, the inverter 60 will be described in detail.

The positive input terminal of the inverter 60 is connected to the positive input terminal of the output control circuit 63. The negative input terminal of the inverter 60 is connected to the negative input terminal of the output control circuit 63.

The input terminal on the positive electrode side of the inverter 60 is connected to the anode / cathode path of the diode D51, the drain / source path of the switching means 61 and the drain / source path of the switching means 62 in series. Of the inverter 60 and a negative input terminal of the inverter 60 via a parallel connection of the capacitors C11 and C12.

The connection point between the switching means 61 and 62 is
The capacitor C is connected via the primary winding L61 of the inductor 64.
11 and the connection point of the capacitor C12. With such a connection, the capacitors C11 and C
12 is provided in parallel with the switching means 61 and 62, respectively.

The output control circuit 63 outputs an oscillation signal a
5, b5 are connected to the discharging and charging side switching means 61, 6
2 and the switching means 61 on the discharging and charging side,
62 are alternately turned on and off, and the on-duty ratios of the switching means 61 and 62 on the discharging and charging sides are controlled based on the output voltage of the rectifier circuit 52.

One input terminal of the discharge lamp 65 is connected to one end of a secondary winding L62 of the inductor 64. The other input terminal of the discharge lamp 65 is connected to the other end of the secondary winding L62 of the inductor 64. A capacitor C13 is connected between both terminals of the discharge lamp 65. With such a connection, the discharge lamp 65 and the capacitor C13 are connected to the output circuit 66.
Is composed.

The capacitance of the capacitor C11 provided in parallel with the switching means 61 is larger than that of the capacitor C11.

Next, the output control circuit 63 will be described in detail.

The output control circuit 63 comprises an on-duty variable circuit 71 and a drive circuit 72.

The on-duty variable circuit 71 detects the output voltage from the rectifier circuit 52 and performs variable control of the duty ratio of the oscillation signals a5 and b5 output from the drive circuit 72 based on the detection result. I have. More specifically, when the voltage VDC5 has a large peak value, the duty ratio at which the oscillation signal b5 goes high is reduced, and the duty ratio at which the oscillation signal a5 goes high is increased.
The on-duty ratio of the switching unit 62 on the charging side is reduced, and the on-duty ratio of the switching unit 61 on the discharging side is increased. When the voltage VDC5 has a small peak value, the duty ratio at which the oscillation signal b5 becomes high level is increased, the duty ratio at which the oscillation signal a5 becomes high level is decreased, and the on-duty ratio of the charging-side switching means 62 is increased. Then, the on-duty ratio of the discharge-side switching means 61 is reduced.

The operation of such a conventional discharge lamp lighting device will be described with reference to FIG.

FIG. 13 shows the output voltage of the rectifier circuit 52 by the output control circuit 63 of FIG.
FIG. 2A is a timing chart showing the relationship of the ON time of FIG. 2A, FIG. 2A shows the output voltage of the rectifier circuit 52, and FIG.
Indicates the on-time of the switching means 61 and 62.

In FIG. 13, when the peak value of the output voltage of the rectifier circuit 52 (the output voltage of the AC power supply 51) is large, the output control circuit 63 reduces the on-period of the switching means 62 on the charging side, The ON period of the switching means 61 is increased. Further, when the peak value of the output voltage of the rectifier circuit 52 is small, the output control circuit 63 increases the on-period of the switching means 62 and shortens the on-period of the switching means 61. Therefore, the on-period of the switching means 61 on the discharging side changes in a reverse relationship to the switching 62 on the charging side.

Next, the operation of such a conventional discharge lamp lighting device will be described.

First, the voltage of the AC power supply 51 is filtered by a filter circuit including choke coils L51 and L52 and a capacitor C51 to remove noise, and is subjected to full-wave rectification by a rectifier circuit 52.
On the other hand, the output control circuit 63 includes switching means 61, 6
2 is alternately switched at a frequency higher than that of the AC power supply 51 to induce a high-frequency AC voltage in the secondary winding L61 of the inductor 64, thereby lighting the discharge lamp 65 at a high frequency. A resonance voltage is generated by the capacitor C12 and the inductor 64, and the action of the resonance voltage causes the capacitor C1
The voltage of 1 is intended to be lower than the unsmoothed DC voltage rectified by the rectifier circuit 52 during one cycle of the switching of the switching means 61 and 62. As a result, even when the peak value of the voltage rectified by the rectifier circuit 52 is low, the power factor improving current is caused to flow, the input power factor from the AC power supply is improved, and the input current can be reduced in distortion.

However, in such a conventional discharge lighting device, when a current is applied or when an overvoltage such as a surge occurs, the input current entering the inverter 60 becomes larger than the rate of increase in the output voltage of the rectifier circuit 52. Since the energy is large, it is difficult to protect the switching means and the output circuit on the charging side.

[0024]

According to such a conventional discharge lamp lighting device, when an overvoltage such as a current is applied or a surge occurs, the input to the inverter is higher than the rate of increase of the output voltage of the rectifier circuit. Since the current increases and the energy increases, it is difficult to sufficiently protect the switching means and the output circuit.

Accordingly, the present invention provides a power supply device capable of obtaining a high-frequency voltage from a DC voltage by using a switching means and sufficiently protecting a switching means and an output circuit when an overvoltage such as a current is supplied or a surge occurs. , A discharge lamp lighting device and a lighting device.

[0026]

According to a first aspect of the present invention, there is provided a power supply apparatus comprising: a rectifier circuit for rectifying an output voltage of an AC power supply to output a non-smooth DC voltage; and a high potential between output terminals of the rectifier circuit. Switching means on the charging side and discharging side provided in series with each other on the low side and the low potential side; a relatively large-capacity first capacitor provided in parallel with the switching means on the discharging side; An inductor interposed between the switching means on the side and the first capacitor;
A second capacitor having a smaller capacity than the first capacitor and forming a resonance circuit with the charging-side switching means and the inductor during an on-period of the charging-side switching means; and the inductor and the second capacitor. An output circuit that obtains a high-frequency output based on the resonance of the current; a current detection device that is provided between the first capacitor and an output terminal on the low potential side of the rectifier circuit and detects a current flowing through the first capacitor A switching circuit on the charging side and a switching side on the discharging side, and when a current value indicated by the current detection circuit is equal to or less than a predetermined value, an on-duty ratio of the switching means on the charging side and the discharging side is changed to the discharging state. The peak value of the current flowing to the switching means on the side is controlled to approach a constant value, and the current value indicated by the current detection circuit is controlled to a predetermined value. If exceeded, the current on-duty of the switching means on the charge side and a control circuit lower than the control in the case of less than a predetermined value; characterized by comprising a.

According to a second aspect of the present invention, there is provided a power supply device comprising: a rectifier circuit for rectifying an output voltage of an AC power supply to output a non-smooth DC voltage; and a high potential side and a low potential side between output terminals of the rectifier circuit. Switching means on the charging side and discharging side provided in series with each other; a first capacitor having a relatively large capacity provided in parallel with the switching means on the discharging side; An inductor interposed between the first capacitor and a capacitor having a smaller capacity than the first capacitor, and forming a resonance circuit with the charging-side switching means and the inductor during the ON period of the charging-side switching means. A second capacitor; an output circuit for obtaining a high-frequency output based on resonance of the inductor and the second capacitor; a first capacitor and the rectifier circuit A current detection circuit provided between the low-potential side output terminal and detecting a current flowing through the first capacitor; and a charging / discharging side switching unit that is turned on / off alternately, and the current detection circuit When the current value indicated by is less than or equal to a predetermined value, the on-duty ratio of the switching means on the charging side and the discharging side is controlled so that the peak value of the current flowing through the switching means on the discharging side approaches a constant, and the current detection circuit And a control circuit for turning off the switching means on the charging side and turning on the switching means on the discharging side when the current value indicated by the control signal exceeds a predetermined value.

According to a third aspect of the present invention, there is provided a power supply device comprising: a rectifier circuit for rectifying an output voltage of an AC power supply to output a non-smooth DC voltage; and a high potential side and a low potential side between output terminals of the rectifier circuit. Switching means on the charging side and discharging side provided in series with each other; a first capacitor having a relatively large capacity provided in parallel with the switching means on the discharging side; An inductor interposed between the first capacitor and a capacitor having a smaller capacity than the first capacitor, and forming a resonance circuit with the charging-side switching means and the inductor during the ON period of the charging-side switching means. A second capacitor; an output circuit for obtaining a high-frequency output based on resonance of the inductor and the second capacitor; a first capacitor and the rectifier circuit A resistor provided between the low-potential output terminal; and a comparator for detecting whether a current flowing through the first capacitor exceeds a predetermined value by comparing a voltage applied to the resistor with a reference value. Switching on and off the switching means on the charging side and the discharging side alternately;
If the comparator indicates that the current has exceeded a predetermined value,
And a control circuit for setting the on-duty of the switching means on the charging side lower than the control when the comparator indicates that the current has not exceeded the predetermined value.

According to a fourth aspect of the present invention, there is provided a power supply device comprising: a rectifier circuit for rectifying an output voltage of an AC power supply to output a non-smooth DC voltage; and a high potential side and a low potential side between output terminals of the rectifier circuit. Switching means on the charging side and discharging side provided in series with each other; a first capacitor having a relatively large capacity provided in parallel with the switching means on the discharging side; An inductor interposed between the first capacitor and a capacitor having a smaller capacity than the first capacitor, and forming a resonance circuit with the charging-side switching means and the inductor during the ON period of the charging-side switching means. A second capacitor; an output circuit for obtaining a high-frequency output based on resonance of the inductor and the second capacitor; A current transformer provided between the output terminal on the low potential side of the rectifier circuit and having a resistor connected between the terminals of the secondary coil; comparing a voltage applied to the resistor connected to the current transformer with a reference value A comparator for detecting whether or not the current flowing through the first capacitor has exceeded a predetermined value; and alternately turning on and off the switching means on the charging side and the discharging side, and the comparator has detected that the current has exceeded the predetermined value. A control circuit for setting the on-duty of the switching means on the charging side to be lower than the control when the comparator indicates that the current has not exceeded a predetermined value. And

According to a fifth aspect of the present invention, there is provided a power supply device for a discharge lamp lighting device, wherein a discharge lamp is provided in an output circuit of the power supply device according to any one of the first to fourth aspects.

According to a sixth aspect of the present invention, there is provided a lighting device comprising: the discharge lamp lighting device according to the fifth aspect; and a lighting fixture body accommodating the discharge lamp lighting device.

According to the present invention, when the current flowing through the first capacitor exceeds a predetermined value, the control circuit sets the on-duty of the switching means on the charging side to be lower than the predetermined value. In this case, it is possible to obtain a high-frequency voltage from the DC voltage using the switching means, and to sufficiently protect the switching means and the output circuit when an overvoltage such as a current is supplied or a surge occurs. .

According to the fifth aspect, the power supply device according to any one of the first to fourth aspects can be applied to a discharge lamp lighting device power supply device.

According to the configuration of claim 6, the discharge lamp lighting device of claim 5 can be applied to a lighting device.

[0035]

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

FIG. 1 is a circuit diagram showing a case where the first embodiment of the power supply circuit according to the present invention is applied to a discharge lamp lighting device.

In FIG. 1, one output terminal of an AC power supply 11 such as a commercial AC power supply is connected to one input terminal of a full-wave rectifier by a rectifier circuit 12 such as a diode bridge via a choke coil L11. The other output terminal is connected to the other input terminal of the rectifier circuit 12 via the choke coil L12. The choke coil L11 and the choke coil L12 are magnetically coupled.

A capacitor C10 is connected between the input terminals of the rectifier circuit 12.

With such a connection, the rectifier circuit 12 rectifies the output voltage of the AC power supply and outputs a non-smoothed DC voltage.

A positive output terminal (high potential output terminal) of the rectifier circuit 12 is connected to a positive input terminal of the inverter 20. Rectifier circuit 12 (low potential side output terminal)
Is connected to the input terminal on the negative side of the inverter 20.

The inverter 20 includes a diode D11 (which can be configured without the diode D11), a switching means 21 such as a MOSFET on the charging side, a switching means 22 such as a MOSFET on the discharging side, an output control circuit 23, For example, an electrolytic capacitor, a second capacitor C12, an inductor 24, for example, an inverter transformer, a current detection circuit 27, a comparator 28, and a current peak value detection circuit 29.

Hereinafter, the inverter 20 will be described in detail.

The input terminal on the positive electrode side (the input terminal on the high potential side) of the inverter 20 is connected in series with the anode-cathode path of the diode D11, the switching means 21, the switching means 22, and the current peak value detection circuit 29. , And connected to the negative input terminal (low potential input terminal) of the inverter 20, and the negative input terminal of the inverter 20 through the series connection of the capacitor C12, the capacitor C11 and the current detection circuit 27. Connected to.

The connection point between the switching means 21 and 22 is connected to the connection point between the capacitors C11 and C12 via the primary winding L21 of the inductor 24.
With such a connection, the capacitors C11 and C12 are
Switching means 22, 2 on the discharging side and the charging side, respectively
1 are provided in parallel.

The current detection circuit 27 is provided between the first capacitor C11 and the negative input terminal of the inverter 20 (the low potential output terminal of the rectifier circuit). The current flowing through the first capacitor C11 is detected, and the detection voltage V1 resulting from the detection is supplied to the comparator 28.

The comparator 28 detects whether the current flowing through the charging path of the first capacitor exceeds a predetermined value by comparing the detection voltage V1 with a reference value, and outputs a detection voltage V2 of the detection result. It is supplied to the control circuit 23.

The current peak value detection circuit 29 is provided between the switching means 22 and the negative input terminal of the inverter 20 (the low-potential output terminal of the rectifier circuit) and flows through the switching means 22 on the discharging side. The peak value of the current is detected, and the detection voltage V3 of the detection result is output to the output control circuit
To supply.

The output control circuit 23 outputs the oscillation signal a
1, b1 are switching means 21 on the charging side and discharging side,
22 and switching means 2 on the charging side and the discharging side.
1 and 22 are alternately turned on and off, and if the comparator 28 does not indicate that the predetermined value has been exceeded, the on-duty ratio of the charging-side and discharging-side switching means 21 and 22 is determined by the current peak value detection circuit. 29 is controlled so as to approach a constant value, and when it is indicated that the detection voltage V2 of the comparator 28 exceeds a predetermined value, the on-duty of the switching means 21 on the charging side is changed to the detection voltage V2.
Is lower than the control in the case where is less than or equal to a predetermined value.

In this case, the output control circuit 23 and the comparator 28
When the current value indicated by the current detection circuit 27 is equal to or less than a predetermined value, the switching means 21 on the charge side and the discharge side,
22 is controlled so that the peak value of the current flowing through the switching means 22 on the discharging side approaches a constant value, and when the current value indicated by the current detection circuit 27 exceeds a predetermined value, the switching means on the charging side is controlled. The on-duty of the control circuit 21 is lower than the control when the current value is equal to or less than a predetermined value.

Further, when the current value indicated by the current detection circuit 27 exceeds a predetermined value, the output control circuit 23 uses a timer circuit to output an overcurrent state determination signal in the circuit for an integral multiple of the switching cycle. Until an overcurrent does not occur, the on-duty of the switching means 21 on the charging side is made lower than the control when the detection voltage V2 is equal to or lower than a predetermined value, and then the overcurrent state determination signal is set to a low level. Return to normal state.

On the other hand, one input terminal of the discharge lamp 25 is connected to one end of the secondary winding L22 of the inductor 24. The other input terminal of the discharge lamp 25 is connected to the other end of the secondary winding L22 of the inductor 24. A capacitor C13 is connected between both terminals of the discharge lamp 25. With such a connection, the discharge lamp 25 and the capacitor C13 form an output circuit 26.

As for the capacitors C11 and C12, the capacity of the capacitor C11 provided in parallel with the switching means 22 on the discharge side is larger.

Next, the output control circuit 23 will be described in detail.

FIG. 2 is a timing chart showing the relationship between the output voltage of the rectifier circuit 12 of FIG. 1 and the on-time of the switching means 21 and 22. FIG. 2 (a) shows the output voltage of the rectifier circuit 12. (B) Switching means 21 and
2 shows the ON time.

In FIG. 2, when the peak value of the output voltage of the rectifier circuit 12 (output voltage of the AC power supply 11) is large,
The on-period of the discharging-side switching means 22 is long, and the on-period of the charging-side switching means 21 is short.
When the peak value of the output voltage of the rectifier circuit 12 is small, the ON period of the switching unit 22 is short, and the ON period of the switching unit 21 is long. The on-period of the charging-side switching means 21 changes in a reverse relationship to the discharging-side switching means 22.

Next, the overall operation of such an embodiment of the present invention will be described.

First, the voltage of the AC power supply 11 is filtered by the filter circuit including the choke coils L11 and L12 and the capacitor C11 to remove noise, and is subjected to full-wave rectification by the rectifier circuit 12.
On the other hand, the output control circuit 23 includes switching means 21 and
2 is alternately switched at a higher frequency than the AC power supply 11 to induce a high-frequency AC voltage in the secondary winding L21 of the inductor 24, thereby lighting the discharge lamp 25 at a high frequency. A resonance voltage is generated by the capacitor C12 and the inductor 24, and the action of the resonance voltage causes the capacitor C1
1 is to be lower than the unsmoothed DC voltage rectified by the rectifier circuit 12 during one cycle of the switching of the switching means 21 and 22. As a result, even when the peak value of the voltage rectified by the rectifier circuit 12 is low, the power factor improving current is supplied, the input power factor from the AC power supply is improved, and the distortion of the input current can be reduced.

FIG. 3 is a timing chart showing a normal operation of the embodiment of the invention shown in FIG. 1. FIG. 3A shows a voltage VDC1 applied to the series connection of the switching means 21 and 22.
3 (b) shows a current I11 flowing through the switching means 21, FIG. 3 (c) shows a current I12 flowing through the switching means 22, and FIG. 3 (d) shows a voltage VC1 applied to the capacitor C11. FIG. 3E shows the voltage VL1 applied to the winding L21.

First, the circuit operation in this case is from t10 to t15.
Is one cycle.

During the period from timing t10 to t11, the capacitor C11, the switching means 22, and the primary winding L21
, A charge stored in the capacitor C11 is released, and the primary winding L of the inductor 24 is released.
The current from the capacitor C11 flows through 21.

In this case, the voltage VDC1 applied to the series connection of the switching means 21 and 22 shown in FIG. 3A has a substantially constant value (in this case, VRec1 changes according to the phase of the output voltage of the AC power supply 51). Are switching means 21 and
Since there is almost no change in one cycle of on / off of No. 2, it is kept substantially constant. ) Is maintained, and the current I11 flowing through the switching means 21 shown in FIG.
The current I12 flowing through the switching means 22 shown in FIG. 3C increases, the voltage VC1 applied to the capacitor C11 shown in FIG. 3D gradually decreases, and the winding L21 shown in FIG.
Maintain a constant negative value.

In the period between timings t11 and t12, the switching means 22 is turned off, the switching means 21 is turned on, the inductor 24 and the capacitor C12 resonate in series, and the resonance current flows from the inductor 24 to the capacitor C12.
Flows towards

In this case, the voltage VDC shown in FIG.
1 increases due to the resonance voltage, and the current I11 flowing through the switching means 21 shown in FIG. 3B suddenly decreases from 0A to the-side, then increases and returns to 0A, and the switching means shown in FIG. The current I12 flowing through 22 becomes 0 A, and the voltage VC1 applied to the capacitor C11 shown in FIG. 3D maintains a substantially constant value. The winding L shown in FIG.
The voltage VL1 applied to 21 increases from a constant negative value.

In the period between timings t12 and t13, in the state where the switching means 22 is turned off and the switching means 21 is turned on, the direction of the resonance current due to the series resonance of the inductor 24 and the capacitor C12 is opposite to that in the case of the timings t11 to t12. Flows to

In this case, the voltage VDC1 shown in FIG. 3A decreases, the current I11 flowing through the switching means 21 shown in FIG. 3B increases from 0 A to the + side, and the switching shown in FIG. The current I12 flowing through the means 22 maintains 0 A, and the voltage V applied to the capacitor C11 shown in FIG.
C1 remains almost constant. Further, the voltage VL1 applied to the winding L21 shown in FIG.

In the period from the timing t13 to the timing t14, the resonance voltage decreases and the voltage between both ends of the capacitors C12 and C11 also tends to decrease.
Current flows through 1.

In this case, the voltage VDC shown in FIG.
1 becomes a substantially constant value VRec1, and the current I11 flowing through the switching means 21 shown in FIG.
The current I flowing through the switching means 22 shown in FIG.
12 maintains 0A, and the capacitor C11 shown in FIG.
, The voltage VC1 applied to the winding L21 gradually increases, and the voltage VL1 applied to the winding L21 shown in FIG.

In the period between timings t14 and t15, the switching means 21 is turned off and the switching means 22 is turned on, and a current flows from the switching means 22 to the capacitor C11 by the energy stored in the inductor 24.

In this case, the voltage VDC shown in FIG.
1 keeps a substantially constant value VRec1, and the current I11 flowing through the switching means 21 shown in FIG.
A, and the current I11 flowing through the switching means 22 shown in FIG.
The voltage VC1 applied to the capacitor C11 shown in FIG. 3 gradually increases, and the voltage VL1 applied to the winding L21 shown in FIG. 3 (e) rapidly drops to the negative side to have a constant negative value.

FIG. 4 is a timing chart for explaining the operation of the discharge lamp lighting device of FIG. 1 relating to the detection of overcurrent. FIG. 4A shows ON / OFF of the switching means 21 on the charging side. 4B shows a current I11 flowing through the switching means 21, FIG. 4C shows a current I12 flowing through the switching means 22, and FIG. 4D shows an overvoltage determination signal in the output control circuit 23.

4A to 4D, in the period D1, normal operation is performed, no overcurrent flows, the detection voltage V2 of the comparator 28 becomes low level, and the output control circuit 23 The overcurrent determination signal becomes low level (L).

In the period D2, an overcurrent flows, and FIG.
The current I11 flowing through the switching means 21 greatly increases, the current flowing through the charging path of the first capacitor C11 increases, and at the end of the period D2, the detection voltage V2 of the comparator 28 becomes high level, and the output control The overcurrent determination signal in the circuit 23 rises to a high level (H). Then, the state shifts to the state of the period D3, and the on-duty of the switching means 21 on the charging side is reduced. As a result, the current I11 flowing through the switching means 21 is greatly reduced, the amplitude of the current I12 flowing through the switching means 22 is reduced from the second switching cycle, and sufficient protection of the switching means 21, 22 and the output circuit 24 can be performed.

As described above, according to the embodiment of the present invention, the current flowing in the charging path of the first capacitor C11 is detected, and based on the detection result, the overcurrent occurs when the switching means 21 on the charging side is turned off. Since the on-duty is made lower than the normal operation, the overcurrent is determined not by the current flowing through the switching means but by the current flowing in other parts. In addition to obtaining voltage, sufficient switching means and output circuits can be protected in the event of an overvoltage such as when a current is applied or a surge occurs, thereby extending the life of the device and improving safety. Can be.

FIG. 5 is a circuit diagram showing a case where the second embodiment of the power supply circuit according to the present invention is applied to a discharge lamp lighting device, and has the same components as those of the embodiment of FIG. Are denoted by the same reference numerals, and description thereof is omitted.

In the inverter 120 shown in FIG. 5, the resistor R101 specifically shows the current detection circuit 27 shown in FIG. 1, and the operational amplifier 121 and the DC power supply 122 show specifically the comparator 28 shown in FIG. It is a thing. Resistance R1
01 is connected to the operational amplifier 121
Of the output control circuit 123 as well as the non-inverting input terminal (+). An output voltage V101 from a DC power supply 122 serving as a reference value is led to an inverting input terminal (−) of the operational amplifier 121. An output terminal of the operational amplifier 121 is connected to a second input terminal of the output control circuit 123.

The output control circuit 123 turns on and off the switching means 21 and 22 on the charging side and the discharging side alternately, and when the output voltage V2 of the operational amplifier 121 is at a low level, the switching means on the charging side and the discharging side. 21 and 22 are controlled so that the detection voltage V3 from the current peak value detection circuit 29 approaches a constant value. When the output voltage V2 of the operational amplifier 121 is at a high level (the current value indicated by the current detection circuit 29). Is greater than a predetermined value), the charging-side switching means 21 is turned off, and the discharging-side switching means 22 is turned on. The turn-off period in this case can be variously applied, such as a period until the next turn-on in one switching cycle, or a predetermined time set by a timer circuit.

FIG. 6 is an explanatory diagram showing the operation of the embodiment of the invention shown in FIG. 5. FIG. 6 (a) shows ON / OFF of the switching means 21 on the charging side, and FIG. 6 (b) shows the voltage V1. ing.

In FIGS. 6A and 6B, during period D11, normal operation is performed, no overcurrent flows, and the input voltage V1 of the non-inverting input terminal (+) of the operational amplifier 12 is DC. It is lower than the output voltage V101 of the power supply 122, and the switching means 21 is turned on and off with a normal on-duty.

In a period D12, an overcurrent flows, and FIG.
(B), the current I11 flowing through the switching means 21 greatly increases, the current flowing through the charging path of the first capacitor C11 increases, and the input voltage V1 of the non-inverting input terminal (+) of the operational amplifier 12 becomes a DC power supply. Output voltage V101
Higher, so that the charging-side switching means 21 is turned off and the discharging-side switching means 22 is turned on. Thereby, the on-duty of the switching means 21 shown in FIG. As a result, the current I11 flowing through the switching means 21 is greatly reduced, the amplitude of the current I12 flowing through the switching means 22 is reduced from the second switching cycle, and sufficient protection of the switching means 21, 22 and the output circuit 24 can be performed.

According to such an embodiment of the invention, the same effects as those of the embodiment of the invention shown in FIG. 1 can be obtained.

FIG. 7 is a circuit diagram showing a first specific example of the switching means 21 and 22 shown in FIGS.

In FIG. 7, the switching means 21 and
2 is an NPN transistor Tr101 and a diode D1
01. NPN transistor Tr1
01: collector is high side (positive side of inverter)
, The emitter is connected to the low side (the negative electrode side of the inverter), and the base is connected to the output control circuit. The emitter of the NPN transistor Tr101 is connected to the NPN transistor D101 via the anode / cathode path of the diode D101.
Connected to the collector of transistor Tr101.

FIG. 8 is a circuit diagram showing a second specific example of the switching means 21 and 22 shown in FIGS.

In FIG. 8, the switching means 21 and
2 is composed of a MOSFET 151. MOS
The FET 151 has a drain connected to the high side (the positive electrode side of the inverter), a source connected to the low side (the negative electrode side of the inverter), and a gate connected to the output control circuit.

FIG. 9 is a circuit diagram showing a second specific example of the current detection circuit 27 shown in FIGS.

In FIG. 9, the current detection circuit 27 includes a current transformer 160 and a resistor R160. The current transformer 160 includes a primary coil L161
Is provided in the charging path of the first capacitor C11,
A resistor R160 is connected between both terminals of the secondary coil L162. A detection voltage V1 is obtained from one end of the resistor R160.

FIG. 10 is a circuit diagram showing a countermeasure to the embodiment of the invention shown in FIGS. 1 and 5, and the same components as those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted.

In FIG. 10, in the present alternative, the switching means 222 on the discharging side and the large-capacity capacitor C211 are provided on the high potential side, and the switching means 221 on the charging side and the capacitor C21 having a smaller capacity than the capacitor C211.
2 is provided on the low potential side. Large capacity capacitor C21
When 1 is provided on the high potential side, the current detection circuit 27 is provided in series with the low potential side of the switching means 221 on the charging side, and the detection voltage of this current detection circuit 227 is supplied to the comparator 228. Then, the detection voltage of the comparator 228 may be supplied to the output control circuit 223.

However, when a large-capacity capacitor (capacitor C11) is provided on the low potential side as in the embodiment of the invention shown in FIGS. 1 and 5, the switching means on the charging side is on the high potential side. When a current detection circuit is provided in series with the charging-side switching means, a problem of a potential difference occurs. Therefore, according to the present invention, a current detection circuit is provided between the first capacitor and a low potential side output terminal of the rectifier circuit.

FIG. 11 is a perspective view showing a lighting device to which any one of the discharge lamp lighting devices according to the embodiment of the invention shown in FIGS. 1 to 9 is applied.

In FIG. 11, a lighting device 501 has discharge lamps 505 and 506 attached to sockets 503 and 504 of a lighting fixture body 502, respectively, and a discharge lamp lighting device 507 is housed therein. 5
05 and 506 are turned on.

With such a structure, the embodiment of the present invention shown in FIGS. 1 to 9 can be applied to a lighting device.

In the embodiment of the present invention shown in FIG. 1, a non-smooth DC voltage is supplied to the inverter 20, but a smooth DC voltage by a rectifying and smoothing circuit may be supplied. In the embodiment of the invention shown in FIG.
Although the configuration is such that the non-smoothed DC voltage is supplied to the inverter 120, the configuration may be such that a non-smoothed DC voltage is supplied.

[0094]

According to the present invention, it is possible to sufficiently protect the switching means and the output circuit when a current is supplied or an overvoltage such as a surge occurs, so that the life of the device can be extended and the safety can be improved. Can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a case where a first embodiment of a power supply circuit according to the present invention is applied to a discharge lamp lighting device.

FIG. 2 is a timing chart showing a relationship between an output voltage of a rectifier circuit and an on-time of a switching means by the output control circuit of FIG. 1;

FIG. 3 is a timing chart showing the operation of the embodiment of the invention shown in FIG. 1;

FIG. 4 is a timing chart illustrating an operation related to detection of overcurrent of the discharge lamp lighting device of FIG. 1;

FIG. 5 is a circuit diagram showing a case where the power supply circuit according to the second embodiment of the present invention is applied to a discharge lamp lighting device.

FIG. 6 is an explanatory view showing the operation of the embodiment of the invention shown in FIG. 5;

FIG. 7 shows a first example of the switching means shown in FIGS. 1 and 5;
FIG. 2 is a circuit diagram showing a specific example of FIG.

FIG. 8 shows a second example of the switching means shown in FIGS. 1 and 5;
FIG. 2 is a circuit diagram showing a specific example of FIG.

FIG. 9 is a circuit diagram showing a second specific example of the current detection circuit shown in FIGS. 1 and 5;

FIG. 10 is a circuit diagram showing a countermeasure to the embodiment of the invention shown in FIGS. 1 and 5;

FIG. 11 shows a lighting device to which any one of the discharge lamp lighting devices according to the embodiment of the invention shown in FIGS. 1 to 9 is applied.

FIG. 12 is a circuit diagram showing an example of a conventional discharge lamp lighting device.

FIG. 13 is a timing chart showing the relationship between the output voltage of the rectifier circuit and the on-time of the switching means by the output control circuit of FIG. 12;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 AC power supply 12 Rectifier circuit 20 Inverter 21 Charge-side switching means 22 Discharge-side switching means 23 Output control circuit 24 Inductor 27 Current detection circuit 28 Comparator C11, C22 Capacitor

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical indication location H05B 41/24 H05B 41/24 Q (72) Inventor Hiroyuki Kudo 4-3 Higashishinagawa, Shinagawa-ku, Tokyo No. 1 Toshiba Lighting & Technology Corporation

Claims (6)

[Claims] 1. A rectifier circuit for rectifying an output voltage of an AC power supply and outputting a non-smooth DC voltage; provided in series with each other between output terminals of the rectifier circuit on a high potential side and a low potential side. Switching means on the charging side and discharging side; a relatively large-capacity first capacitor provided in parallel with the switching means on the discharging side; and an intermediate between the switching means on the discharging side and the first capacitor. An inserted inductor; a second capacitor having a capacity smaller than that of the first capacitor and forming a resonance circuit with the charging-side switching means and the inductor during an ON period of the charging-side switching means; An output circuit for obtaining a high-frequency output based on resonance of the inductor and the second capacitor; and between the first capacitor and an output terminal on the low potential side of the rectifier circuit. A current detection circuit for detecting a current flowing through the first capacitor; and alternately turning on and off the switching means on the charging side and the discharging side, and a current value indicated by the current detection circuit being equal to or less than a predetermined value. In the case, the on-duty ratio of the switching means on the charging side and the discharging side is controlled such that the peak value of the current flowing through the switching means on the discharging side approaches a constant value, and the current value indicated by the current detection circuit exceeds a predetermined value. And a control circuit for setting the on-duty of the switching means on the charging side to be lower than the control when the current value is equal to or less than a predetermined value. 2. A rectifier circuit for rectifying an output voltage of an AC power supply to output a non-smooth DC voltage; and a rectifier circuit provided in series between output terminals of the rectifier circuit on a high potential side and a low potential side, respectively. Switching means on the charging side and discharging side; a relatively large-capacity first capacitor provided in parallel with the switching means on the discharging side; and an intermediate between the switching means on the discharging side and the first capacitor. An inserted inductor; a second capacitor having a capacity smaller than that of the first capacitor and forming a resonance circuit with the charging-side switching means and the inductor during an ON period of the charging-side switching means; An output circuit for obtaining a high-frequency output based on resonance of the inductor and the second capacitor; and between the first capacitor and an output terminal on the low potential side of the rectifier circuit. A current detection circuit for detecting a current flowing through the first capacitor; and alternately turning on and off the switching means on the charging side and the discharging side, and a current value indicated by the current detection circuit being equal to or less than a predetermined value. In the case, the on-duty ratio of the switching means on the charging side and the discharging side is controlled such that the peak value of the current flowing through the switching means on the discharging side approaches a constant value, and the current value indicated by the current detection circuit exceeds a predetermined value. And a control circuit for turning off the switching means on the charging side and turning on the switching means on the discharging side. 3. A rectifier circuit for rectifying an output voltage of an AC power supply to output a non-smooth DC voltage; and a rectifier circuit provided in series between output terminals of the rectifier circuit on a high potential side and a low potential side, respectively. Switching means on the charging side and discharging side; a relatively large-capacity first capacitor provided in parallel with the switching means on the discharging side; and an intermediate between the switching means on the discharging side and the first capacitor. An inserted inductor; a second capacitor having a capacity smaller than that of the first capacitor and forming a resonance circuit with the charging-side switching means and the inductor during an ON period of the charging-side switching means; An output circuit for obtaining a high-frequency output based on resonance of the inductor and the second capacitor; and between the first capacitor and an output terminal on the low potential side of the rectifier circuit. A comparator for detecting whether a current flowing through the first capacitor exceeds a predetermined value by comparing a voltage applied to the resistor with a reference value; and switching between the charging side and the discharging side. When the means is alternately turned on and off and the comparator indicates that the current has exceeded a predetermined value, the on-duty of the charging-side switching means indicates that the comparator has not exceeded the predetermined value. And a control circuit for lowering the control when the power supply is turned on. 4. A rectifier circuit for rectifying an output voltage of an AC power supply and outputting a non-smooth DC voltage; and a rectifier circuit provided in series between output terminals of the rectifier circuit on a high potential side and a low potential side, respectively. Switching means on the charging side and discharging side; a relatively large-capacity first capacitor provided in parallel with the switching means on the discharging side; and an intermediate between the switching means on the discharging side and the first capacitor. An inserted inductor; a second capacitor having a capacity smaller than that of the first capacitor and forming a resonance circuit with the charging-side switching means and the inductor during an ON period of the charging-side switching means; An output circuit for obtaining a high-frequency output based on the resonance of the inductor and the second capacitor; and a primary coil connected to the first capacitor and the low-potential output of the rectifier circuit. A current transformer provided between the power transformer terminal and a resistor connected between the terminals of the secondary coil; and flowing to the first capacitor by comparing a voltage applied to the resistor connected to the current transformer with a reference value. A comparator for detecting whether the current exceeds a predetermined value; and alternately turning on and off the switching means on the charging side and the discharging side, and when the comparator indicates that the current has exceeded a predetermined value, A control circuit for reducing the on-duty of the switching means on the charging side to be lower than the control when the comparator indicates that the current has not exceeded the predetermined value. 5. A discharge lamp lighting device comprising a discharge lamp provided in an output circuit of the power supply device according to claim 1. 6. A lighting device comprising: the discharge lamp lighting device according to claim 5; and a lighting fixture main body that houses the discharge lamp lighting device.