JP2007273173A - Discharge lamp lighting device and lighting apparatus - Google Patents

Abstract

Disclosed is a discharge lamp lighting device capable of preventing thermal destruction of a switching element of a DC power supply circuit and reducing the cost, and a lighting fixture including the discharge lamp lighting device.
A discharge lamp lighting device 1 includes a first control means 6 for controlling an on / off operation of a switch element FET1 of a DC power supply circuit 2 so that a predetermined DC voltage is output from the DC power supply circuit 2, and an inverter circuit. The second control means 7 for controlling the operating frequency 3 and the current flowing through the switching element FET1 are detected, and the DC voltage output from the DC power supply circuit 2 is lowered when the current is a predetermined value or more. And third control means 8 for controlling one control means 6.
[Selection] Figure 1

Description

  The present invention relates to a discharge lamp lighting device and a lighting fixture for lighting a discharge lamp at high frequency.

  As this type of discharge lamp lighting device, for example, a discharge lamp lighting device capable of lighting a plurality of types of discharge lamps having different rated lamp powers has been proposed (see, for example, Patent Document 1). In this discharge lamp lighting device according to the prior art, an inverter circuit is connected to a DC power supply circuit (chopper circuit), and a resonance circuit including a ballast inductor and a resonance capacitor is connected to a field effect transistor of the inverter circuit. A discharge lamp is connected in parallel. Then, by setting the oscillation frequency of the inverter circuit in the vicinity of the resonance frequency at the time of no load of the resonance circuit, even when a discharge lamp having a different rated power is lit, a substantially constant lamp current flows through the discharge lamp. Yes.

If the discharge lamp is controlled so that a substantially constant lamp current flows, the lamp power decreases as the lamp voltage of the discharge lamp decreases when the ambient temperature of the discharge lamp becomes high. It is possible to suppress the temperature rise of each component of the discharge lamp lighting device incorporated in the lighting fixture. Thereby, there is an advantage that a discharge lamp lighting device can be formed at low cost without using high-quality electronic components such as high heat resistance for each component.
Japanese Patent Laying-Open No. 2005-310755 (page 6, FIG. 1)

  Since the discharge lamp lighting device of Patent Document 1 is controlled so that a substantially constant lamp current flows through the discharge lamp, for example, when the ambient temperature of the lighting fixture (discharge lamp) decreases, the lamp voltage of the discharge lamp increases. The lamp power increases and the power consumption in the inverter circuit increases. As a result, the current flowing through the field effect transistor as the switching element of the DC power supply circuit (chopper circuit) also increases, and the loss associated with the on / off operation (turn-off) in the field effect transistor increases. Then, the heat generation of the field effect transistor is increased, which may cause the field effect transistor to be thermally destroyed.

  As a means for avoiding thermal destruction of the field effect transistor, a field effect transistor having high heat resistance and low loss can be used, but it is expensive and it is not desirable because it increases the cost of the discharge lamp lighting device. Therefore, usually, a heat conductive material such as an aluminum plate or silicone resin is brought into close contact with the field effect transistor, and heat from the field effect transistor is radiated from the aluminum plate or the heat conductive material. However, if the loss of the field effect transistor is large, the heat generation exceeds the heat dissipation, and the field effect transistor may be thermally destroyed.

  An object of the present invention is to provide a discharge lamp lighting device capable of preventing thermal destruction of a switch element of a DC power supply circuit and reducing the cost, and a lighting fixture including the discharge lamp lighting device.

  The invention of the discharge lamp lighting device according to claim 1 includes a switching element, a DC power supply circuit that outputs a DC voltage by an on / off operation of the switching element, and an inverter that converts the DC voltage into a high-frequency AC voltage and outputs it. A discharge lamp that is lit in response to the high-frequency AC voltage; first control means for controlling on / off operation of the switch element so that a predetermined DC voltage is output from the DC power supply circuit; Second control means for controlling an operating frequency; first control means for detecting a current flowing through the switch element and reducing a DC voltage output from a DC power supply circuit when the current is equal to or greater than a predetermined value; And a third control means for controlling.

  In the present invention and each of the following inventions, each configuration is as follows unless otherwise specified.

  The DC power supply circuit includes a DC voltage generation circuit that outputs a DC voltage, and a chopper circuit that converts the DC voltage output from the DC voltage generation circuit into a DC voltage by chopping by a switch element. The

  The discharge lamp lighting device of the present invention is not limited to the one in which a plurality of types of discharge lamps having different rated lamp powers are lit at the same constant current or substantially constant current, and at least one type of discharge lamp is lit at a constant current. Can be made.

  According to the present invention, even if the ambient temperature of the discharge lamp changes, the second control means causes the inverter circuit to operate at a predetermined operating frequency, so that a substantially constant current flows through the discharge lamp. For example, when the ambient temperature of the discharge lamp decreases, the lamp voltage increases. Since the discharge lamp is controlled so that a substantially constant current flows, the lamp power increases as the lamp voltage increases.

  When the lamp power increases, the power consumption of the inverter circuit increases, so the output current of the DC power supply circuit increases and the current flowing through the switch element increases. As the lamp power increases, when the current flowing through the switch element increases and exceeds a predetermined value, the third control means changes the operating frequency of the switch element with respect to the first control means and Control is performed to reduce the output voltage (DC voltage) of the power supply circuit. As a result, the DC voltage output from the DC power supply circuit decreases, the current supplied to the inverter circuit decreases, and the current flowing through the switch element falls below a predetermined value. The switch element does not generate heat abnormally and does not break down.

  The invention of the discharge lamp lighting device according to claim 2 includes a switching element, a DC power supply circuit that outputs a DC voltage by an on / off operation of the switching element, and an inverter that converts the DC voltage into a high-frequency AC voltage and outputs it. A discharge lamp that is lit in response to the high-frequency AC voltage; first control means for controlling on / off operation of the switch element so that a predetermined DC voltage is output from the DC power supply circuit; Second control means for controlling the operating frequency; detecting a current flowing through the switch element, and changing the operating frequency of the inverter circuit when the current is equal to or greater than a predetermined value so that the current flowing through the discharge lamp is reduced. Or a third control means for controlling the second control means so as to stop the operation of the inverter circuit. The features.

  According to the present invention, for example, when the ambient temperature of the discharge lamp becomes low and the current flowing through the switch element of the DC power supply circuit increases to a predetermined value or more, the third control means changes to the second control means. On the other hand, the operation frequency of the inverter circuit is changed so that the current flowing through the discharge lamp decreases, or the operation of the inverter circuit is stopped. As the current flowing through the discharge lamp decreases, the current supplied from the DC power supply circuit to the inverter circuit decreases, and the current flowing through the switch element of the DC power supply circuit falls below a predetermined value. Alternatively, when the operation of the inverter circuit stops, no current is supplied from the DC power supply circuit to the inverter circuit, and the current flowing through the switch element of the DC power supply circuit falls below a predetermined value. As a result, the switch element does not generate heat abnormally and does not break down thermally.

  The invention of the lighting fixture according to claim 3 comprises the discharge lamp lighting device according to claim 1 or 2; and a lighting fixture main body in which the discharge lamp lighting device is disposed. To do.

  According to the present invention, since the discharge lamp lighting device according to claim 1 or 2 is provided, the luminaire includes the discharge lamp lighting device that prevents the switch element of the DC power supply circuit from being thermally destroyed to stop the operation. Is provided.

  According to the first aspect of the present invention, when a current of a predetermined value or more flows through the switch element of the DC power supply circuit, the output voltage of the DC power supply circuit is reduced to prevent thermal destruction of the switch element. Failure can be prevented, and the switch element can be configured at low cost, and the discharge lamp lighting device can be reduced in cost.

  According to the invention of claim 2, when a current exceeding a predetermined value flows through the switching element of the DC power supply circuit, the operating frequency of the inverter circuit is changed to reduce the current flowing through the discharge lamp, or the operation of the inverter circuit is stopped. Thus, the thermal destruction of the switch element of the DC power supply circuit is prevented, so that the failure of the discharge lamp lighting device can be prevented, and the switch element can be configured at low cost and the discharge lamp lighting device can be made inexpensive. .

  According to the invention of claim 3, since the discharge lamp lighting device according to claim 1 or 2 is provided, the discharge lamp can be lit at a constant current by preventing failure even when the ambient temperature becomes low. An inexpensive lighting apparatus can be provided.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. First, a first embodiment of the present invention will be described.

  1 to 3 show a first embodiment of the present invention, FIG. 1 is a circuit diagram of a discharge lamp lighting device, FIG. 2 is a change diagram of a lamp voltage with respect to a lamp current indicating constant current control, and FIG. The drain current of the switch element with respect to the characteristics is shown, (a) is a change diagram of the drain current with respect to the lamp power, (b) is a change diagram of the drain current with respect to the lamp voltage.

  In FIG. 1, a discharge lamp lighting device 1 includes a DC power supply circuit 2, an inverter circuit 3, a fluorescent lamp 4 and a fluorescent lamp 5 as discharge lamps, a chopper circuit control circuit 6 as first control means, and a second control. An inverter circuit control circuit 7 as means and a protection control circuit 8 as third control means are provided.

  The DC power supply circuit 2 includes a DC voltage generation circuit 9 and a chopper circuit 10. The DC voltage generating circuit 9 includes a rectifier 11 and a filter capacitor C1, converts the commercial AC voltage of the commercial AC power supply Vs into a DC voltage, and outputs the DC voltage between both ends of the capacitor C1. The negative electrode side of the capacitor C1 is connected to the ground E via the capacitor C2. The input side of the rectifier 11 is connected to a commercial AC power supply Vs via a noise prevention transformer 12.

  The chopper circuit 10 is connected between both ends of an inductor L1 connected between both ends of the capacitor C1, a series circuit of a field effect transistor FET1 as a switching element and a resistor R1, and a series circuit of the field effect transistor FET1 and the resistor R1. It has a series circuit of a backflow preventing diode D1 and a smoothing capacitor C3. The gate and source of the field effect transistor FET1 are connected to the chopper circuit control circuit 6. The resistor R1 detects a drain current flowing through the field effect transistor FET1.

  The chopper circuit control circuit 6 turns on / off the field effect transistor FET1 to boost the DC voltage generated across the capacitor C1. As a result, a predetermined DC voltage, for example, 410 V is generated between both ends of the smoothing capacitor C3. That is, the chopper circuit control circuit 6 controls the on / off operation of the field effect transistor FET1 so that a predetermined DC voltage (410 V) is output from the DC power supply circuit 2. The DC voltage output from the DC power supply circuit 2 (the voltage across the smoothing capacitor C3) becomes the input voltage of the inverter circuit 3.

  The inverter circuit 3 includes a series circuit of a field effect transistor FET2 and a field effect transistor FET3, and the series circuit is connected between both ends of the smoothing capacitor C3. The gate and source of the field effect transistor FET2 and the field effect transistor FET3 are connected to the drive circuit 13, respectively. The drive circuit 13 is connected to the inverter circuit control circuit 7.

  The drive circuit 13 alternately supplies a drive voltage between the gates and sources of the field effect transistor FET2 and the field effect transistor FET3 in accordance with a control signal (pulse signal) from the inverter circuit control circuit 9. As a result, the field effect transistor FET2 and the field effect transistor FET3 are alternately turned on and off. By this on / off operation, the DC voltage output from the DC power supply circuit 2 is converted into a high-frequency AC voltage and is output between the drain and source of the field effect transistor FET3. Between the drain and source of the field effect transistor FET3 is between the outputs of the inverter circuit 3.

  Between the outputs of the inverter circuit 3, a resonance circuit 14 including a DC cut capacitor C4, an inductor L2, and a resonance capacitor C5 is connected via fluorescent lamps 4 and 5 connected in series. One end of each of the filament electrode 4b of the fluorescent lamp 4 and the filament electrode 5a of the fluorescent lamp 5 is connected to each other, and the other end of each of the filament electrode 4b and the filament electrode 5a is between both ends of the preheating winding L2a of the inductor L2. It is connected to the. A resonance capacitor C5 is connected to the non-power supply side of each of the filament electrode 4a and the filament electrode 5b. That is, the fluorescent lamp 4 and the fluorescent lamp 5 are connected in series between both ends of the capacitor C5.

  The resonance circuit 14 resonates with the high-frequency AC voltage output from the inverter circuit 3 to turn on the fluorescent lamp 4 and the fluorescent lamp 5 at high frequency. The fluorescent lamp 4 and the fluorescent lamp 5 are, for example, the same type of fluorescent lamp with a rated lamp power of 23 W. In the resonance circuit 14, for example, the inductance of the inductor L2 is 1.0 mH, the capacitances of the DC cut capacitor C4 and the resonance capacitor C5 are 68 nF and 4.7 nF, respectively, and the natural resonance frequency f0 is 73 kHz. .

  The inverter circuit 3 controls the field effect transistors FET2 and FET3 so that a constant current flows through the fluorescent lamps 4 and 5 under the control of the inverter circuit control circuit 7, that is, the frequency f1 in the vicinity of the natural resonance frequency f0. The on / off operation (operating frequency) is controlled. The total lamp characteristics of the fluorescent lamps 4 and 5 connected in series are, for example, a lamp voltage of 108 V, a lamp current of 0.4 A, and a lamp power of 42.5 W at an ambient temperature of 25 ° C.

  Then, the inverter circuit control circuit 7 turns on / off the field effect transistors FET2 and FET3 so that a constant current (0.4 A) flows through the fluorescent lamps 4 and 5 even if the ambient temperature of the fluorescent lamps 4 and 5 changes. Is configured to control. That is, when the ambient temperature of the fluorescent lamps 4 and 5 changes, the lamp voltage (lamp power) changes. However, even if the lamp voltage changes, as shown in FIG. 2, the operating frequency of the field effect transistors FET2 and FET3 ( ON / OFF frequency) is controlled to be a frequency f1 (75 kHz) in the vicinity of the natural resonance frequency f0 (73 kHz) of the resonance circuit 14.

  The protection control circuit 8 includes a comparator 15, a series circuit of a current-limiting resistor R 2 and a capacitor C 6 connected between the source of the field effect transistor FET 1 of the chopper circuit 10 and the ground E, and a smoothing capacitor C 3 of the chopper circuit 10. And a series circuit of resistors R3 to R6, each of which is a voltage dividing resistor, connected between the positive electrode side and the ground E. The middle point a1 of the resistors R4 and R5 is connected to the chopper circuit control circuit 6. The series circuit of the resistors R3 to R6 detects the output voltage of the chopper circuit 10 (DC power supply circuit 2), and a voltage correlated with the output voltage is input to the chopper circuit control circuit 6. That is, the chopper circuit control circuit 6 detects the output voltage of the DC power supply circuit 2.

  The positive side of the capacitor C6 is connected to the non-inverting input terminal of the comparator 15, and a voltage correlated with the drain current flowing through the field effect transistor FET1 is input. The reference voltage of the reference power supply Vref1 is input to the inverting input terminal of the comparator 15. The comparator 15 compares the voltage correlated with the drain current with the reference voltage, and outputs a high signal from the output terminal when the voltage correlated with the drain current is equal to or higher than the reference voltage. That is, the comparator 15 detects the drain current flowing through the field effect transistor FET1 of the chopper circuit 10, and outputs a high signal when the drain current is equal to or greater than a predetermined value. The predetermined value is set to a current at which the field effect transistor FET1 is not thermally destroyed.

  The output terminal of the comparator 15 is connected to the middle point a2 of the resistors R5 and R6 via the resistor R7 and the capacitor C7. The high signal output from the output terminal of the comparator 15 is stabilized by the resistor R7 and the capacitor C7 and superimposed on the voltage across the resistor R6. As a result, the potential at the middle point a1 of the resistors R4 and R5 increases, and the voltage input to the chopper circuit control circuit 6 increases. Then, the chopper circuit control circuit 6 increases the operating frequency (on / off frequency) of the field effect transistor FET1 and decreases the predetermined DC voltage (410V) output from the chopper circuit 10 (DC power supply circuit 2).

  Thus, the protection control circuit 8 detects the drain current flowing through the field effect transistor FET1 of the chopper circuit 10, and uses a predetermined DC voltage (410V) output from the DC power supply circuit 2 when the drain current is equal to or higher than a predetermined value, for example. The chopper circuit control circuit 6 is controlled to be lowered to 300V.

  Next, the operation of the first embodiment of the present invention will be described.

  When the commercial AC power supply Vs is turned on, the chopper circuit control circuit 6 turns on and off the field effect transistor FET1 so that a predetermined DC voltage (410 V) is generated across the smoothing capacitor C3 of the chopper circuit 10. . As a result, a predetermined DC voltage (410 V) is output from the DC power supply circuit 2.

  Then, when the fluorescent lamps 4 and 5 are turned on, the inverter circuit control circuit 7 changes the on / off operation of the field effect transistors FET2 and FET3 of the inverter circuit 3 to the operating frequency f1 in the vicinity of the natural resonant frequency f0 (73 kHz) of the resonant circuit 14. (75 kHz). By this control, a constant current (0.4 A) flows through the fluorescent lamps 4 and 5 connected in series, and a substantially constant luminous flux is emitted from the fluorescent lamps 4 and 5. The total lamp characteristics of the fluorescent lamps 4 and 5 connected in series are, for example, a lamp voltage of 108 V, a lamp current of 0.4 A, and a lamp power of 42.5 W at an ambient temperature of 25 ° C. At this time, the drain current flowing through the field effect transistor FET1 of the chopper circuit 10 is 1.6 A as shown in FIG.

  In the fluorescent lamps 5 and 6, the lamp voltage and the lamp power increase or decrease according to the change in the ambient temperature. When the ambient temperature of the fluorescent lamps 5 and 6 decreases, the lamp voltage increases as the ambient temperature decreases, and the lamp power increases due to constant current control by the inverter circuit control circuit 7.

  Since constant current is supplied from the inverter circuit 3 to the fluorescent lamps 5 and 6, when the lamp power of the fluorescent lamps 5 and 6 increases, power consumption in the subsequent stage from the inverter circuit 3 increases with respect to the commercial AC power supply Vs. Thereby, the input current of the inverter circuit 3 increases, and the output current from the chopper circuit 10 (DC power supply circuit 2) increases.

  When the output current of the chopper circuit 10 increases, the drain current flowing through the field effect transistor FET1 increases. That is, as shown in FIG. 3, the drain current increases as the lamp voltage and lamp power of the fluorescent lamps 4 and 5 rise. The drain current flowing in the field effect transistor FET1 of the chopper circuit 10 gradually increases from 1.6A as the ambient temperature of the fluorescent lamps 4 and 5 decreases from 25 ° C.

  When the drain current flowing in the field effect transistor FET1 becomes a predetermined value, for example, 2.2 A or more, a high signal is output from the comparator 15 of the protection control circuit 8. Then, the potential at the middle point a1 of the resistors R4 and R5 rises, and a change in this potential is detected by the chopper circuit control circuit 6. The chopper circuit control circuit 6 raises the operating frequency of the field effect transistor FET1 and lowers the DC voltage generated across the smoothing capacitor C3 to, for example, 300V.

  When the voltage across the smoothing capacitor C3 decreases, the output current supplied to the inverter circuit 3 decreases, and the drain current flowing through the field effect transistor FET1 becomes less than a predetermined value (2.2 A). No high signal is output. The chopper circuit control circuit 6 continues to reduce the voltage across the smoothing capacitor C3 until the commercial AC power supply Vs is turned on again or an external reset signal (external signal) is input.

  As the input current of the inverter circuit 3 decreases, the constant current control value of the inverter circuit 3 decreases, and the lamp voltage, lamp current, and lamp power of the fluorescent lamps 4 and 5 decrease.

  As described above, when the drain current flowing through the field effect transistor FET1 exceeds a predetermined value, the voltage across the smoothing capacitor C3 (the output of the DC power supply circuit 2) is controlled by the chopper circuit control circuit 6 of the protection control circuit 8. Voltage) is decreased, and the drain current becomes lower than a predetermined value. As a result, a drain current of a predetermined value or more does not continuously flow through the field effect transistor FET1, thereby preventing thermal destruction of the field effect transistor FET1. That is, failure of the discharge lamp lighting device 1 is prevented.

  Further, since a drain current of a predetermined value or more does not continuously flow through the field effect transistor FET1, it is not necessary to use an expensive field effect transistor FET1 with a small turn-off loss or high heat resistance. Further, a heat conductive material such as a silicone resin that is relatively inexpensive can be used as a heat radiating material that closely contacts the field effect transistor FET1 and dissipates heat from the field effect transistor FET1 instead of an aluminum (Al) plate. As a result, the discharge lamp lighting device 1 can be configured at low cost.

  Next, a second embodiment of the present invention will be described.

  4 and 5 show a second embodiment of the present invention, FIG. 4 is a circuit diagram of a discharge lamp lighting device, FIG. 5 shows constant current control, (a) is a control diagram at normal temperature, and (b) ) Is a control diagram at a low temperature. Note that the same parts as those in FIG.

  In the discharge lamp lighting device 16 shown in FIG. 4, the protection control circuit 17 is configured such that the output terminal of the comparator 15 is connected to the inverter circuit control circuit 7 in the discharge lamp lighting device 1 shown in FIG. . That is, when a drain current of a predetermined value, for example, 2.2 A or more flows through the field effect transistor FET1 of the chopper circuit 10, a high signal is input from the comparator 15 to the inverter circuit control circuit 7.

  Then, the inverter circuit control circuit 7 controls the inverter circuit 3 so that the lamp current of the fluorescent lamps 4 and 5 becomes 0.4 A as shown in FIG. The on / off operation of the field effect transistors FET2 and FET3 is controlled. Further, when a high signal is input from the comparator 15, as shown in FIG. 5B, the constant current (0.4A) flowing through the fluorescent lamps 4 and 5 is reduced so that the lamp current becomes 0.29A. Thus, the on / off frequency (operating frequency) and on-duty of the field-effect transistor FET1 of the chopper circuit 10 are changed with respect to the chopper circuit control circuit 6. The constant current reduction control is continued until the commercial AC power source Vs is turned on again or an external reset signal (external signal) is input.

  When the ambient temperature of the fluorescent lamps 4 and 5 decreases from room temperature (for example, 25 ° C.), the lamp power and the lamp voltage increase according to the decrease, and the output current from the chopper circuit input to the inverter circuit increases. As a result, the drain current flowing through the field effect transistor FET1 increases.

  When the ambient temperature of the fluorescent lamps 4 and 5 is further lowered and the drain current flowing through the field effect transistor FET1 becomes a predetermined value (2.2 A) or more, a high signal is output from the comparator 15, and the high signal is converted into an inverter circuit. Is input to the control circuit 7. The inverter circuit control circuit 7 controls the chopper circuit control circuit 6 to change the on / off frequency (operating frequency) and on-duty of the field effect transistor FET1 of the chopper circuit 10, and flows to the fluorescent lamps 4 and 5. The constant current (0.4A) is reduced to 0.29A. Alternatively, the inverter circuit control circuit 7 increases the operating frequency of the field effect transistors FET2 and FET3 of the inverter circuit 3 so that the constant current (0.4A) flowing through the fluorescent lamps 4 and 5 reaches 0.29A. Reduce. As a result, the current supplied from the chopper circuit 10 to the inverter circuit 3 decreases, and the drain current flowing through the field effect transistor FET1 becomes lower than a predetermined value (2.2 A). Since a drain current of a predetermined value or more does not continuously flow through the field effect transistor FET1, thermal breakdown of the field effect transistor FET1 is prevented. That is, the discharge lamp lighting device 16 is prevented from being damaged due to thermal destruction of the field effect transistor FET1.

  The inverter circuit control circuit 7 may be configured to stop the on / off operation of the field effect transistors FET2 and FET3 of the inverter circuit 3 when a high signal from the comparator 15 is input. By the stop, the fluorescent lamps 4 and 5 are turned off, and a drain current of a predetermined value or more does not flow to the field effect transistor FET1 of the chopper circuit 10.

  Next, a third embodiment of the present invention will be described.

  FIGS. 6A and 6B are lighting fixtures showing a third embodiment of the present invention, in which FIG. 6A is a partially cutaway schematic side view, and FIG. 6B is a schematic top view. Note that the same parts as those in FIG.

  A lighting fixture 18 shown in FIG. 6 is an embedded lighting fixture embedded in a construction such as a ceiling, and a lighting fixture body 19 formed in a substantially square box shape is attached to the construction. The luminaire main body 19 is provided with a reflection frame 20 on the opening side, and three lamp sockets 21, a lamp holder (not shown) and a V reflection plate 22 on the bottom side. The three fluorescent lamps 4 and 5 are respectively attached to the lamp socket 21 and the lamp holder. The fluorescent lamps 4 and 5 are of the same type, and are compact fluorescent lamps dedicated to high frequency with a U-shaped bulb.

  Discharge lamp lighting devices 23 and 24 are disposed in the space between the luminaire main body 19 and the reflection frame 20. The discharge lamp lighting devices 23 and 24 are obtained by removing the fluorescent lamps 4 and 5 from the discharge lamp lighting device 1 shown in FIG. The discharge lamp lighting device 23 lights two fluorescent lamps 4 and 5 connected in series, and the discharge lamp lighting device 24 lights one fluorescent lamp 4.

  The radiated light emitted from the three fluorescent lamps 4 and 5 is emitted from the opening side of the luminaire main body 19 as direct light or reflected light reflected by the reflection frame 20 and the V reflection plate 22.

  And since the three fluorescent lamps 4 and 5 are constant-current controlled, the lighting fixture 18 radiate | emits a substantially constant light beam. And since the discharge lamp lighting devices 23 and 24 are provided, it can be configured at low cost.

The circuit diagram of the discharge lamp lighting device which shows the 1st Embodiment of this invention. Similarly, the change figure of the lamp voltage with respect to the lamp current which shows constant current control. Similarly, the drain current of the switch element with respect to the lamp characteristics is shown, (a) is a change diagram of the drain current with respect to the lamp power, (b) is a change diagram of the drain current with respect to the lamp voltage. The circuit diagram of the discharge lamp lighting device which shows the 2nd Embodiment of this invention. Similarly, constant current control is shown, (a) is a control diagram at normal temperature, (b) is a control diagram at low temperature. It is a lighting fixture which shows the 3rd Embodiment of this invention, (a) is a partially notched schematic side view, (b) is a schematic top view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,16 ... Discharge lamp lighting device 2 ... DC power supply circuit 3 ... Inverter circuits 4, 5 ... Fluorescent lamp 6 as discharge lamp ... Inverter circuit control circuit 7 as first control means ... As second control means Control circuit for chopper circuit 8, 17 ... Protection control circuit 18 as third control means ... Lighting fixture 19 ... Lighting fixture body

Claims (3)

A DC power supply circuit comprising a switch element and outputting a DC voltage by an on / off operation of the switch element;
An inverter circuit for converting the DC voltage into a high-frequency AC voltage and outputting it;
A discharge lamp that lights in response to the high-frequency AC voltage;
First control means for controlling the on / off operation of the switch element so that a predetermined DC voltage is output from the DC power supply circuit;
Second control means for controlling the operating frequency of the inverter circuit;
Third control means for detecting a current flowing through the switch element and controlling the first control means so as to reduce the DC voltage output from the DC power supply circuit when the current is greater than or equal to a predetermined value;
A discharge lamp lighting device comprising: A DC power supply circuit comprising a switch element and outputting a DC voltage by an on / off operation of the switch element;
An inverter circuit for converting the DC voltage into a high-frequency AC voltage and outputting it;
A discharge lamp that lights in response to the high-frequency AC voltage;
First control means for controlling the on / off operation of the switch element so that a predetermined DC voltage is output from the DC power supply circuit;
Second control means for controlling the operating frequency of the inverter circuit;
The current flowing through the switch element is detected, and when the current exceeds a predetermined value, the operating frequency of the inverter circuit is changed to reduce the current flowing through the discharge lamp, or the operation of the inverter circuit is stopped. And third control means for controlling the second control means;
A discharge lamp lighting device comprising: A discharge lamp lighting device according to claim 1 or 2;
A lighting fixture body provided with the discharge lamp lighting device;
The lighting fixture characterized by comprising.

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