JPH07274524A - Power system, discharge lamp lighting device, and lighting system - Google Patents

Abstract

PURPOSE:To keep the output of an inverter circuit constant and protect the circuit by controlling the inverter circuit based on the output of a load current detecting means, in an equipment wherein a resonance circuit is connected to an output terminal of the inverter circuit and a load is connected to the resonance circuit through a capacitor for ballast. CONSTITUTION:Commercial ac voltage E is rectified by a full-wave rectifier 21 and then is smoothed by a capacitor C11, and the smoothed voltage is applied to allow self-exited oscillation of an inverter circuit 22 with its saturable transformer Tr11. As a result, high-frequency ac is induced in a secondary winding Tr12b of an insulation transformer Tr12 and thereby fluorescent lamps FL1, FL2 light. At that time, the load current is detected by a load current detecting circuit 24 and the base current of a transistor Q13 is controlled based on the detection result. By this method, an impedance of a control winding Tr11d is changed and the oscillation conditions of the inverter circuit 22 such as a frequency is changed and thereby the current which flows in the fluorescent lamps FL1, FL2 is kept constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device, a discharge lamp lighting device, and a lighting device for keeping the output of an inverter circuit constant.

[0002]

2. Description of the Related Art As a conventional discharge lamp lighting device of this type, for example, a structure shown in FIG. 9 is known.

As shown in FIG. 9, an input terminal of a full-wave rectifier 1 such as a diode bridge is connected to a commercial AC power source E, a capacitor C1 is connected to an output terminal of the full-wave rectifier 1, and a capacitor C1 is connected to the capacitor C1. Is connected to the inverter circuit 2. In this inverter circuit 2, a field effect transistor Q1 and a field effect transistor Q2 are connected in series, and between the gate and source of the field effect transistor Q1 is
The resistor R1 and the output winding Tr1b of the saturable transformer Tr1 are connected, and the resistor R2 and the output winding Tr1c of the saturable transformer Tr1 are connected between the gate and the source of the field effect transistor Q2.

Further, between the drain and the source of the field effect transistor Q2, the detection winding of the saturable current transformer Tr1 is provided.
The primary winding Tr2a of the insulation transformer Tr2 is connected via the resonance circuit 3 of the Tr1a, the choke coil L1 and the capacitor C2 and the capacitor C3, and the fluorescent lamps FL1 and FL2 are connected in series to the secondary winding Tr2b of the insulation transformer Tr2. It is connected to the.

Further, a voltage fixing means 4 for detecting a voltage and setting it to a constant voltage is connected between both ends of the capacitor C2, and an output terminal of the voltage fixing means 4 is a transistor Q3.
Connected to the base of.

A capacitor C4 is connected between the collector and emitter of the transistor Q3.
A diode bridge 5 composed of diodes D1, D2, D3, D4 is connected to C4, and the output terminal of this diode bridge 5 is connected to the control winding Tr1d of the saturable transformer Tr1. Is forming.

Then, the voltage of the commercial AC power source E is full-wave rectified by the full-wave rectifier 1 and smoothed by the capacitor C1, and then the field effect transistor Q1 and the field effect transistor Q2 are alternately turned on and off, and the fluorescent lamp FL1, High-frequency voltage is applied to FL2 to turn on high-frequency.

Further, the voltage constant means 4 allows the capacitor C2
By detecting the voltage of the above, the saturation time of the saturable transformer Tr1 is changed by controlling the transistor Q3, and the output voltage of the inverter circuit 2 is controlled to be constant.

[0009]

However, in the case of the discharge lamp lighting device shown in FIG. 9, the fluorescent lamps FL1 and FL2 are used.
Looking at the relationship between the lamp voltage and the lamp current from the side, the control approaches that shown in FIG.

Therefore, even if the ambient temperature of the fluorescent lamps FL1, FL2 rises and the luminous efficiency improves, the inverter circuit 2
Has a problem that the temperature of the isolation transformer Tr2 etc. may rise more than necessary because it supplies almost constant power.

The present invention has been made in view of the above problems, and an object thereof is to provide a power supply device, a discharge lamp lighting device, and a lighting device for the purpose of circuit protection and the like.

[0012]

According to a first aspect of the present invention, there is provided a power supply device in which a resonance circuit is provided at an output terminal of an inverter circuit, and a load is connected from the resonance circuit via a ballast capacitor. It is provided with a load current detecting means for detecting a current and a current controlling means for controlling the inverter circuit based on the current detected by the load current detecting means to make the load current constant.

According to a second aspect of the present invention, there is provided a power supply device in which a resonance circuit is provided at an output terminal of an inverter circuit, and a load is connected from the resonance circuit via a ballast capacitor. Detection means,
A load voltage detection means for detecting the voltage of the load; and a control means for controlling the inverter circuit based on the current detected by the load current detection means and the voltage detected by the load voltage detection means. is there.

According to a third aspect of the present invention, there is provided a power supply device in which a resonance circuit is provided at an output terminal of an inverter circuit, and a load is connected in parallel from the resonance circuit through an insulation transformer to detect the voltage of the insulation transformer. And a voltage control means for controlling the inverter circuit to keep the load voltage constant and using this voltage as a power source.

In the discharge lamp lighting device according to claim 4, the load according to claims 1 to 3 is a discharge lamp.

According to a fifth aspect of the present invention, there is provided the discharge lamp lighting device according to the fourth aspect in which the lighting apparatus is provided with a fixture body.

[0017]

In the power supply device according to the present invention, the load current detecting means detects the load current, the inverter circuit is controlled based on the current detected by the load current detecting means, and the current controlling means keeps the load current constant. Since the inverter circuit outputs, the control based on the current value can be performed, the temperature rise of the circuit elements and the like can be prevented, and the circuit is protected.

According to another aspect of the power supply device of the present invention, the load current detecting means detects the load current, the load voltage detecting means detects the load voltage, and the load current detecting means detects the current and the load voltage detecting means. The inverter circuit is controlled on the basis of the voltage detected by the control means to make it constant by the control means, and the inverter circuit outputs, so that the control based on the current value can be performed.
It is possible to prevent the temperature rise of circuit elements and the like and protect the circuit.

According to another aspect of the power supply device of the present invention, the voltage control means detects the voltage of the insulating transformer to control the inverter circuit to keep the load voltage constant and use this voltage as a power source. Circuit protection is provided.

In the discharge lamp lighting device according to the fourth aspect, since the load according to the first to third aspects is the discharge lamp, it is possible to protect the circuit.

In the lighting device according to the fifth aspect, since the discharge lamp lighting device according to the fourth aspect is provided with the main body of the fixture, circuit protection and the like can be achieved.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the illumination device of the present invention will be described below with reference to the drawings.

In FIG. 2, reference numeral 11 denotes an instrument body, and a pair of lamp sockets 12 are attached to both ends of the instrument body 11, and fluorescent lamps FL1 and FL2 as discharge lamps are attached to these lamp sockets 12 to make the instrument body 11 Inside the surface facing the fluorescent lamps FL1, FL2 and the fluorescent lamps FL1, FL2
A reflecting surface 13 is formed between the reflecting surface 13 and a discharge lamp lighting circuit 14 is housed in the reflecting surface 13.

In the discharge lamp lighting circuit 14, as shown in FIG. 1, the commercial AC power source E is connected to the input terminal of a full-wave rectifier 21, such as a diode bridge.
A capacitor C11 is connected to the output terminal of 21, and a half-bridge type inverter circuit 22 is connected to the capacitor C11. In this inverter circuit 22, a field effect transistor Q11 and a field effect transistor Q12 are connected in series, a resistor R11 and an output winding Tr11b of a saturable transformer Tr11 are connected between the gate and source of the field effect transistor Q11, and A resistor R12 and a saturable transformer Tr11 are connected between the gate and source of the effect transistor Q12.
The output winding Tr11c of is connected.

Further, the detection winding Tr11 of the saturable transformer Tr11 is provided between the drain and the source of the field effect transistor Q12.
The primary winding Tr12a of the insulating transformer Tr12 is connected via the resonance circuit 23 of the choke coil L11 and the capacitor C12 and the capacitor C13 for ballast, and the fluorescent lamps FL1, FL2 are connected to the secondary winding Tr12b of the insulating transformer Tr12. Are connected in series.

Further, the primary winding Tr of the saturable transformer Tr12
A current transformer Tr13 is provided on the 12a side, the current transformer Tr13 is connected to a load current detection circuit 24 as a load current detection means, and the output terminal of the load current detection circuit 24 is connected to the base of the transistor Q13. There is.

Also, the collector of this transistor Q13,
A capacitor C14 is connected between the emitters, and a diode bridge 25 consisting of diodes D11, D12, D13, and D14 is connected to this capacitor C14. The output terminal of this diode bridge 25 is the control winding of the saturable transformer Tr11.
It is connected to Tr11d, and these form the current control means 26.

Next, the operation of the embodiment shown in FIG. 1 will be described.

First, the voltage of the commercial AC power source E is converted into a full-wave rectifier.
Full-wave rectification by 21 and smoothing by the capacitor C11, the inverter circuit 22 self-oscillates according to the saturable transformer Tr11, and induces high-frequency alternating current in the secondary winding Tr12b of the isolation transformer Tr12.
The fluorescent lamps FL1 and FL2 are lit at high frequency.

Further, the load current detection circuit 24 detects the current based on the fluorescent lamps FL1 and FL2, and the transistor Q13
By controlling the base current of the control winding Tr11d to change the impedance of the control winding Tr11d and change the oscillation state such as the frequency of the inverter circuit 22, the fluorescent lamps FL1, FL
Keep the current flowing through 2 constant.

As described above, if current control is performed, the load characteristics of the fluorescent lamps FL1 and FL2 become constant current characteristics. Therefore, as shown in FIG. 3, even when the ambient temperature is high, H
Even when the ambient temperature is low, the voltage of the fluorescent lamps FL1 and FL2 can be lowered even when the ambient temperature is L, so that it is possible to prevent the temperature of the insulating transformer Tr12 and other electric parts from rising more than necessary, and it is especially housed in the case. It is effective for things.

Next, another embodiment will be described with reference to FIG.

The embodiment shown in FIG. 4 is the same as the embodiment shown in FIG. Connect a resistor R15 of several Ω to several Ω, connect an amplifier 27 to this resistor R15 to detect the current, and use the integrating circuit of resistor R16 and capacitor C15 as the average voltage. Connect the base of, connect the resistor R17 to the collector of this transistor Q14, connect the resistor R18 to the emitter, connect the capacitor C17 between these resistor R17 and resistor R18,
Ground the connection point of resistor R18 and capacitor C17. Further, a diode D16, a diode D17 and a capacitor C18 are connected to the connection point of the capacitor C17 and the resistor R17, and the current control means 28 is formed by these, and the capacitor C1
Connect 7 to the output winding Tr11c of saturable transformer Tr11.

Then, the resistor R15 converts the current into a voltage value, which is amplified by the amplifier 27 to control the base current of the transistor Q14 to change the substantial resistance value between the emitter and collector of the transistor Q14, By changing the impedance of the output winding Tr11c of the saturable transformer Tr11 and changing the oscillation state such as the frequency of the inverter circuit 22, the current value flowing through the fluorescent lamps FL1, FL2 is always made constant.

Another embodiment will be described with reference to FIG.

In the embodiment shown in FIG. 5, a half-bridge type inverter circuit 31 is connected to a DC power source V, and the inverter circuit 31 is formed by a series circuit of a field effect transistor Q21 and a field effect transistor Q22. .

A series circuit of a choke coil L21 and a capacitor C21 is connected between the drain and source of the field effect transistor Q22 to form a resonance circuit 32. In addition, the primary winding Tr21a of the isolation transformer Tr21 and the ballast capacitor are connected in parallel with the capacitor C21.
The series circuit of C22 is connected, and the secondary winding Tr21b of the isolation transformer Tr21 has a fluorescent lamp as a load and discharge lamp.
FL is connected.

Furthermore, the ballast capacitor C22 is connected to a load current detecting circuit 33 as a load current detecting means via a DC cutting capacitor C23 as a DC removing capacitor and a resistor R21. In this load current detection circuit 33, a resistor R22 is connected to a resistor R22, and a diode D21, a capacitor C23 and a resistor R23 are connected to this resistor R22.
And the resistor R24 to the inverting input terminal of the operational amplifier 34, the non-inverting input terminal is connected to the reference power source E1, and the resistor R25 is connected between the inverting input terminal and the output terminal of the operational amplifier 34. Then, it is connected via a diode D22 to a control circuit 35 as voltage control means, and this control circuit 35 controls the gates of the field effect transistor Q21 and field effect transistor Q22 of the inverter circuit 31.

A load voltage detecting means 36 is connected to the primary winding Tr21a of the choke coil L21 and the insulating transformer Tr21 via a resistor R26. The load voltage detecting means 36 is connected to the non-inverting input terminal of the operational amplifier 37 via the resistor R26, the resistor R27, the diode D23, the capacitor C24, the resistor R28 and the resistor R29. Further, the output terminal of the operational amplifier 38 whose inverting input terminal is connected to the diode D21 and whose non-inverting input terminal is connected to the reference power source E2 is connected to the connection point of the diode D23 and the resistor R29 via the diode D24. Further, a resistor R30 is connected between the output terminal and the inverting input terminal of the operational amplifier 37, and the reference power supply E3 is connected to the non-inverting input terminal. The output terminal of the operational amplifier 37 is connected to the control circuit 35 via the diode D25.

Next, the operation of the embodiment shown in FIG. 5 will be described.

First, the voltage of the DC power supply V is converted into an inverter circuit.
The high-frequency alternating current is converted at 31 and the high-frequency alternating current is induced in the secondary winding Tr21b of the insulating transformer Tr21 to turn on the fluorescent lamp FL at a high frequency.

Here, the load voltage detecting means 36 detects the direct current cut current by the direct current cut capacitor C23 from the current corresponding to the current of the fluorescent lamp FL flowing through the ballast capacitor C22, and the current of the fluorescent lamp FL decreases. If so, the frequency or the like is changed to increase the current from the inverter circuit 31, and conversely, if the current is increased, the current is decreased to control the constant current value.

Further, the load voltage detecting means 36 is used to detect the fluorescent lamp FL.
The voltage of the isolation transformer Tr21 corresponding to the voltage of is detected, and if the voltage value increases, the inverter circuit 31
When the voltage is increased, the voltage is decreased to control the voltage value constant. In addition, in the load voltage detecting means 36, when the fluorescent lamp FL is removed, the voltage of the primary winding Tr12a of the insulating transformer Tr12 decreases, but the voltage of the resistor R22 increases, and the non-inversion by the operational amplifier 38 occurs. Then, the control circuit 35 stops the oscillation of the inverter circuit 31 or lowers the output.

Then, as shown in FIG. 6, constant current control or constant voltage control is performed.

According to the embodiment shown in FIG. 5, when detecting the current, the load current detecting circuit 33 detects the current from the ballast capacitor C22 through the DC cutting capacitor C23, so that the conventional transformer is unnecessary. Therefore, the mounting area can be reduced, the device can be downsized, and the cost can be reduced. Further, since both the current and the voltage of the fluorescent lamp FL are detected and controlled, the deep dimming of the fluorescent lamp FL can be performed conventionally.

Further, another embodiment will be described with reference to FIG.

The embodiment shown in FIG. 7 is a commercial AC power source E.
Is connected to an input terminal of a full-wave rectifier 41 such as a diode bridge, and a smoothing capacitor C31 is connected to an output terminal of the full-wave rectifier 41 to form a power supply circuit 42. A half-bridge type inverter circuit 43 is connected to the power supply circuit 42, and the inverter circuit 43 is formed by a series circuit of a field effect transistor Q31 and a field effect transistor Q32.

A series circuit of a choke coil L31 and a capacitor C32 is connected between the drain and source of the field effect transistor Q32 to form a resonance circuit 44. In addition, a series circuit of the primary winding Tr31a of the insulating transformer Tr31 and the ballast capacitor C33, and a series circuit of the primary winding Tr32a of the insulating transformer Tr32 and the ballast capacitor C34 are connected in parallel with the capacitor C32 to provide insulation. The fluorescent lamp FL1 is connected to the secondary winding Tr31b of the transformer Tr31, and the fluorescent lamp FL2 is connected to the secondary winding Tr32b of the insulating transformer Tr32.

Furthermore, the ballast capacitor C33 is connected to a load current detecting circuit 45 as load current detecting means through a DC cutting capacitor C35 as a DC removing capacitor, a diode D31 and a resistor R31, and at the same time, a ballast is connected. For the capacitor C34, a load current detection circuit is also provided via a DC cut capacitor C36 as a DC removal capacitor, a diode D32 and a resistor R32.
Connected to 45. This load current detection circuit 45 is
Resistor R33 is connected to R31, resistor R34 is connected to resistor R32, and these resistors R33 and R34 are connected to capacitor C3.
7 and the diode D33, or the capacitor C38 and the diode D34, and is grounded to the power source Vcc through the resistor R35 and the resistor R36. Also the resistance
The connection point of R35 and resistor R36 is connected to the inverting input terminal of the operational amplifier 46 through the resistor R37, the reference power supply E11 is connected to this non-inverting input terminal, and the inverting input terminal and the output terminal of the operational amplifier 46 are connected. Resistor R38 is connected. Then, it is connected via a diode D35 to a control circuit 47 as control means, and this control circuit 47 controls the gates of the field effect transistor Q31 and the field effect transistor Q32 of the inverter circuit 43.

Also, the choke coil L31 and the insulation transformer
A load voltage detecting means 48 is connected to the primary winding Tr31a of the Tr31 and the primary winding Tr32a of the insulating transformer Tr32 via a resistor R39. This load voltage detecting means 48 is composed of a resistor R39
To resistor R40, diode D36, capacitor C39, resistor R41
, And is connected to the inverting input terminal of the operational amplifier 49 via the resistors R42 and R43. The non-inverting input terminal is grounded via the reference power supply E12 and the resistor R44, and the resistor R45 is connected between the inverting input terminal and the output terminal. Further, the resistors R33 and R34 are connected to a diode D37 and a diode D38, respectively. The diodes D37 and D38 are grounded via a resistor R46 to a power supply Vcc and via a resistor R47. The connection point of these resistors R46 and R47 is connected to the non-inverting input terminal of the operational amplifier 50, the inverting input terminal is connected to the reference power supply E13, and the output terminal is grounded via the series circuit of the resistors R48 and R49. Has been done. Also the resistance
The connection point of R48 and the resistor R49 is connected to the base of the transistor Q33, the collector of the transistor Q33 is connected to the resistor R43 via the resistor R50, the reference power source E12, and the emitter is grounded. The output terminal of the operational amplifier 49 is connected to the control circuit 47 via the diode D40.

Next, the operation of the embodiment shown in FIG. 7 will be described.

First, the voltage of the commercial AC power source E is changed to a full-wave rectifier.
Full-wave rectification at 41, smoothing at capacitor C31, conversion to high-frequency AC at inverter circuit 43, secondary winding Tr31b of isolation transformer Tr31 and secondary winding Tr32b of isolation transformer Tr32.
A high-frequency alternating current is induced to turn on the fluorescent lamps FL1 and FL2 at a high frequency.

Here, the load current detection circuit 45 detects the direct current cut current by the DC cut capacitor C35 from the current corresponding to the current of the fluorescent lamp FL1 flowing through the ballast capacitor C33, and the ballast capacitor C3 is detected.
The current corresponding to the current of the fluorescent lamp FL2 flowing in 4 is detected by cutting the direct current with the DC cut capacitor C36, and if the current of the fluorescent lamp FL1 or fluorescent lamp FL2 decreases, it is based on the output of the operational amplifier 46. By changing the frequency or the like, the current from the inverter circuit 43 is increased. On the contrary, when the current is increased, the current is decreased to control the constant current value.

Further, the load voltage detecting means 48 is used to detect the fluorescent lamp FL.
The control circuit 47 detects the higher voltage of the isolation transformer Tr31 or the isolation transformer Tr32 corresponding to the voltage of 1 and FL2, and based on the output of the operational amplifier 49 when the voltage value increases.
The voltage of the inverter circuit 43 is decreased by, and conversely, when the voltage is increased, the voltage is decreased to control the constant voltage value. The load voltage detection means 48 uses a fluorescent lamp.
When either FL1 or fluorescent lamp FL2 is removed, the voltage of resistor R33 or resistor R34 becomes high, so non-inverting output is made by operational amplifier 50, transistor Q33 is turned on, and inverting output is made by operational amplifier 49. The control circuit 47 stops the oscillation of the inverter circuit 43 or reduces the output.

According to the embodiment shown in FIG. 7, in detecting the current, the load current detection circuit 45 is operated by passing the current from the ballast capacitor C33 and the ballast capacitor C34 through the DC cut capacitor C35 or the DC cut capacitor C36. Since the conventional transformer is not required, the mounting area can be reduced, the size of the device can be reduced, and the cost can be reduced. In particular, the fluorescent lamps FL1, FL
Effective when there are two or more. Further, since both the current and the voltage of the fluorescent lamp FL are detected and controlled,
It is possible to perform deep dimming of the fluorescent lamp FL as compared with the conventional one. Furthermore, the voltage detection is performed in one path, and two fluorescent lamps FL1,
Fluorescent lamp FL1, because it follows the higher voltage of FL2,
Even if there are multiple FL2s, the structure is not particularly complicated.

Further, another embodiment will be described with reference to FIG.

The embodiment shown in FIG. 8 is a commercial AC power source E.
An input terminal of a full-wave rectifier 51 such as a diode bridge is connected to, and a boost chopper circuit 52 is connected to an output terminal of the full-wave rectifier 51.

This boost chopper circuit 52 is a full-wave rectifier 51.
Between the output terminals of the choke coil L51 and transistor Q
A series circuit of 51 is connected, a series circuit of a diode D51 and a capacitor C51 is connected between the collector and the emitter of the transistor Q51, and a chopper control circuit 53 is connected to the base of the transistor Q51.

On the output side of the boost chopper circuit 52,
A half-bridge type inverter circuit 54 is connected, and this inverter circuit 54 connects a transistor Q52 and a transistor Q53 in series, and the bases of these transistors Q52 and Q53 have an inverter control circuit 55.
Are connected.

Further, a choke coil L52 and a capacitor C52 are provided between the collector and the emitter of the transistor Q53.
A resonant circuit 56 consisting of is connected to this capacitor C52
Is the ballast capacitor C53 and isolation transformer Tr.
The series circuit of the primary winding Tr51a of 51, the ballast capacitor C54 and the series circuit of the primary winding Tr52a of the insulating transformer Tr52 are connected in parallel.

The secondary winding Tr51b of the isolation transformer Tr51
Is connected to the fluorescent lamp FL1, and the secondary winding Tr52b of the insulating transformer Tr52 is connected to the fluorescent lamp FL2.

Further, the primary winding Tr51 of the isolation transformer Tr51
The diode D51 or diode D52 is connected to the primary winding Tr52a of the isolation transformer Tr52 and the resistor R51.
Also, the capacitor C55 is connected in parallel to the resistor R52 and is grounded via the resistor R52. Also, the resistance R51
The inverting input terminal of the operational amplifier 57 is connected to the connection point of the resistor R52 and the resistor R52, the reference power supply E21 is connected to the non-inverting input terminal, the resistor R53 is connected between the output terminal and the inverting input terminal, and the output terminal is It is connected to the inverter control circuit 55.

Further, the diode D51 and the diode D5
2 is connected to the chopper control circuit 53 via the resistor R54, the Zener diode ZD51 and the capacitor C56.

Next, the operation of the embodiment shown in FIG. 8 will be described.

First, the voltage of the commercial AC power source E is converted into a full-wave rectifier.
Full-wave rectification at 51, transistor C5 at chopper control circuit 53
1 is controlled to boost by the boost chopper circuit 52 and the power factor is improved, and the inverter control circuit 55 controls the transistor Q52 and the transistor Q53 to convert to high frequency by the inverter circuit 54, and the fluorescent lamps FL1 and FL2 are lit at high frequency. Let

The primary winding Tr51 of the insulating transformer Tr51
a and the primary winding Tr52a of the isolation transformer Tr52 as a power source for the inverter control circuit 55 via the diode D51 and the diode D52 and a power source for the chopper control circuit 53. In addition, the primary winding Tr of these isolation transformer Tr51
51a and the isolation transformer Tr52's primary winding Tr52a and the voltage from the diode D51 and the diode D52, the operational amplifier 57 compares it with the reference power supply E21, and outputs it.The inverter control circuit 55 oscillates the inverter circuit 54 according to the voltage. Control and constant voltage control.

According to the embodiment shown in FIG. 8, the normal 2
When both of the two fluorescent lamps FL1 and FL2 are lit, the power is supplied by the power from the two diodes D51 and D52, and one of the fluorescent lamps FL1 and FL2 is used.
In the case of 1 and FL2 only, the power is supplied from the power from either diode D51 or diode D52, but since voltage feedback is applied, the voltage is kept constant and safe.

Further, since the feedback circuit and the power source are composed of the same component, the circuit structure is simplified and the chopper control circuit 53 and the inverter control circuit are provided.
There is no problem even if the 55 has a large current capacity.

[0069]

According to the power supply device of the present invention, the load current detecting means detects the load current, the inverter circuit is controlled based on the current detected by the load current detecting means, and the current control means operates. Since the inverter circuit outputs with the load current kept constant, control based on the current value can be performed.
The temperature rise of circuit elements can be prevented and the circuit can be protected.

According to the power supply device of the second aspect, the load current detecting means detects the load current, the load voltage detecting means detects the load voltage, and the load current detecting means detects the current and the load voltage. Since the inverter circuit controls the inverter circuit based on the voltage detected by the detection unit and makes it constant by the control unit, and the inverter circuit outputs, the control based on the current value can be performed and the temperature rise of the circuit element can be prevented and the circuit protection can be performed. You can

According to the power supply device of the third aspect, the voltage control means detects the voltage of the insulating transformer to control the inverter circuit to make the load voltage constant and to use this voltage as the power supply. Therefore, the circuit can be protected.

According to the discharge lamp lighting device of the fourth aspect,
Since the load according to claims 1 to 3 is a discharge lamp,
Circuit protection can be achieved.

According to the lighting device of the fifth aspect, since the discharge lamp lighting device of the fourth aspect is provided with the instrument main body, it is possible to protect the circuit.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of a discharge lamp lighting device of the present invention.

FIG. 2 is a perspective view showing the same illumination device.

FIG. 3 is a graph showing the relationship between lamp current and lamp voltage.

FIG. 4 is a circuit diagram showing a discharge lamp lighting device of another embodiment of the same.

FIG. 5 is a circuit diagram showing a discharge lamp lighting device according to another embodiment of the above.

FIG. 6 is a graph showing the relationship between output current and output voltage.

FIG. 7 is a circuit diagram showing a discharge lamp lighting device of still another embodiment of the same.

FIG. 8 is a circuit diagram showing a discharge lamp lighting device according to still another embodiment of the present invention.

FIG. 9 is a circuit diagram showing a conventional discharge lamp lighting device.

FIG. 10 is a graph showing the relationship between lamp current and lamp voltage.

[Explanation of symbols]

11 Instrument main body 22, 31, 43, 54 Inverter circuit 23, 32, 44. 56 Resonant circuit 24, 33, 45 Load current detection circuit as load current detection means 26 Current control means 35 Control circuit as voltage control means 36, 48 Load voltage detection means C13, C22 Ballast capacitors FL, FL1, FL2 Load, fluorescent lamp as discharge lamp Tr21, Tr51, Tr52 Insulation transformer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical indication H05B 41/24 Q

Claims (5)

[Claims] 1. A power supply device in which a resonance circuit is provided at an output terminal of an inverter circuit and a load is connected from the resonance circuit through a ballast capacitor, and a load current detection means for detecting a current of the load, and the load current. A power supply device comprising: a current control unit that controls the inverter circuit based on the current detected by the detection unit to keep the load current constant. 2. A power supply device in which a resonance circuit is provided at an output terminal of an inverter circuit, and a load is connected from the resonance circuit via a ballast capacitor, wherein a load current detection unit for detecting a current of the load, A load voltage detection means for detecting a voltage; and a control means for controlling the inverter circuit based on the current detected by the load current detection means and the voltage detected by the load voltage detection means. Power supply. 3. A power supply device in which a resonance circuit is provided at an output terminal of an inverter circuit, and a load is connected in parallel from the resonance circuit via an insulation transformer, and a voltage of the insulation transformer is detected to control the inverter circuit. A power supply device, comprising: a voltage control unit that keeps a load voltage constant and uses this voltage as a power supply. 4. The discharge lamp lighting device according to claim 1, wherein the load is a discharge lamp. 5. A lighting device comprising the discharge lamp lighting device according to claim 4 and a fixture body.