JP2000260593A - Discharge lamp lighting device and lighting equipment - Google Patents

Abstract

[PROBLEMS] To provide a discharge lamp lighting device and a lighting apparatus which can obtain a constant brightness even when a lamp temperature changes and can suppress a discharge lamp from going out even in a deep dimming state. A lamp voltage value and a lamp current value of a discharge lamp are detected, and a ratio of a lamp current value to a lamp voltage value increases as a dimming ratio of the discharge lamp decreases. A detection value varying means 15 for varying at least one of the current values in accordance with the dimming signal; a lamp power calculating means 8 for calculating a lamp power value based on the lamp voltage value and the lamp current value varied by the detection value varying means 15; The dimming signal is input from the dimming signal output means 14, the output of the inverter circuit 4 is varied according to the dimming signal, the discharge lamp 5 is dimmed, and the lamp power value calculated by the lamp power calculating means 8 And the control circuit 7 for controlling the inverter circuit 4 so that the discharge lamp lighting device 1 is configured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dimmable discharge lamp lighting device and a lighting apparatus.

[0002]

2. Description of the Related Art Conventionally, this type of discharge lamp lighting device has
For example, it is disclosed in JP-A-1-294398 (prior art). This discharge lamp lighting device 30 has the configuration shown in FIG.
, A DC smoothing circuit 31 for converting the AC power supply AC into DC, an inverter circuit 3 including switching transistors 32 and 33, capacitors 34 and 35, an inverter transformer 36, a resonance capacitor 37, and the like.
8, a current transformer 40 for detecting a current flowing through the discharge lamp 39, an adder 41, a drive control circuit 42, and a variable impedance element 43 for adjusting the output of the current circuit in accordance with the dimming signal.

When the discharge lamp 39 is turned on, a signal corresponding to the load current flowing through the discharge lamp 39 is transmitted to the current transformer 4.
0 is detected and applied to one input of the adder 41 via the variable impedance element 43. A signal corresponding to the load voltage of the inverter circuit 38 is input to the other input of the adder 41 from the secondary coil N4 of the inverter transformer 36. The adder 41 adds these signals and inputs them to the drive control circuit 42 as control signals. The drive control circuit 42 changes the switching frequency of the switching transistors 32 and 33 based on the control signal, and controls the output of the inverter circuit 38 so that the sum of the load current and the load voltage becomes constant. Thus, the discharge lamp lighting device 30 has pseudo constant power output characteristics.

Further, the discharge lamp lighting device 30 can adjust the impedance of the variable impedance element 43 by a dimming signal, and can change the magnitude of the output of the current transformer 40 according to the dimming signal. Therefore, the dimming of the discharge lamp 39 can be performed. In this case, as shown in FIG. 5, the no-load voltage even in the dimming state, that is, the output voltage V20 when the current is zero.
, The load curve and the VI of the discharge lamp 39
That is, the angle of intersection with the curve is increased, and the disappearance of the curve is eliminated.

[0005]

The load curve shown in FIG. 5 is described by a straight line, but actually, as shown in FIG.
This is a parabolic curve, and the angle at which the load curve intersects with the VI curve of the lamp 39 is small in a region where the dimming state is deep, that is, in the vicinity of near zero current. Therefore, for example, when the discharge lamp 39 is used in an environment having a low ambient temperature and the lamp temperature is lowered, the VI curve of the lamp 39 moves as shown by a broken line in the drawing, and the load curve is shifted. No longer cross, lamp 39
May disappear. In particular, since a lamp having a small tube diameter is easily affected by the ambient temperature, the lamp voltage in a low-temperature atmosphere is significantly increased, and the lamp may be easily extinguished.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a discharge lamp lighting device and a lighting apparatus which can obtain a constant brightness even when the lamp temperature changes, and can suppress the light from disappearing even in a deep dimming state.

[0007]

According to the present invention, there is provided a discharge lamp lighting device comprising: a DC power supply; an inverter circuit which receives the DC power supply and outputs a high frequency power; Or a discharge lamp that can be lit by dimming; dimming signal output means for outputting a dimming signal for dimming and lighting the discharge lamp; dimming of the discharge lamp by detecting a lamp voltage value and a lamp current value of the discharge lamp Detection value varying means for varying at least one of the lamp voltage value and the lamp current value in accordance with the dimming signal so that the ratio of the lamp current value to the lamp voltage value increases as the ratio decreases; Lamp power calculating means for calculating a lamp power value based on the changed lamp voltage value and lamp current value; a dimming signal input from a dimming signal output means, Are provided with; is dimmed discharge lamp by varying the output of the inverter circuit in response to a control circuit for controlling the inverter circuit so that the lamp power value calculated by the lamp power calculation unit.

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

The DC power supply outputs a DC voltage such as a battery, a DC power supply, a rectified or rectified and smoothed commercial AC voltage, and a rectified and smoothed circuit obtained by connecting a rectifying and smoothing circuit and a chopper circuit to a commercial AC power supply. Should be fine.

The light control may be either continuous light control or step light control.

The lamp voltage value is the magnitude of the lamp voltage, and the lamp current value is the magnitude of the lamp current. These are detected not only by directly detecting the voltage or current applied to the discharge lamp, but also by detecting the voltage or current. And those that detect those correlated with.

The dimming ratio of the discharge lamp is set so that the dimming ratio is close to the unlit state when the dimming ratio is low, and close to the all-light state when the dimming ratio is high. For example, the all-light state is 100%, and the unlit state is 0%. Therefore, a decrease in the dimming ratio of the discharge lamp means that dimming is performed from the all-light state to the unlit state.

The detection value changing means increases the lamp current value by multiplying the lamp current value by a gradually increasing positive number or increases the lamp voltage value as the dimming ratio of the discharge lamp decreases. The lamp voltage value may be reduced by dividing by a number, or the ratio of the lamp current value to the lamp voltage value may be increased by a combination of the two. However, since the lamp current value decreases as the dimming ratio decreases, it is preferable to increase the lamp current value.

The detection value varying means may vary at least one of the lamp voltage value and the lamp current value in accordance with the output of the inverter circuit in addition to the dimming signal.

The detected value varying means causes the ratio of the lamp current value to the lamp voltage value to increase as the dimming ratio of the discharge lamp decreases. And the dimming ratio is 0
In the vicinity of%, the control circuit controls the inverter circuit to perform constant current control. The angle at which the load curve of the output characteristics of the device intersects the VI curve of the discharge lamp is increased, and the discharge lamp is prevented from going out. Further, the control circuit controls the inverter circuit so as to have the lamp power value calculated by the lamp power calculation means according to the dimming signal from the dimming signal output means.

According to the present invention, the control circuit controls the inverter circuit so as to have a lamp power value corresponding to the dimming signal, and controls the inverter circuit with constant current control when the dimming ratio is close to 0%. Therefore, the discharge lamp is turned on at a constant lamp power value corresponding to the dimming signal, and it is possible to suppress extinguishing even in a deep dimming state where the dimming ratio is around 0%.

According to a second aspect of the present invention, there is provided a discharge lamp lighting device according to the first aspect, wherein the detection value changing means is configured to output the light when the discharge lamp has a dimming ratio below a predetermined level. At least one of the voltage value and the lamp current value is varied.

The control circuit controls the inverter circuit at a constant power until the discharge lamp reaches a predetermined level of dimming ratio, and controls the inverter circuit to perform constant current control at a dimming ratio below the predetermined level so that the dimming ratio becomes 0%. In the vicinity, constant current control is performed.

According to the present invention, when the dimming ratio becomes equal to or less than a predetermined level at which the discharge lamp is easily extinguished, the control circuit performs the constant current control of the inverter circuit. Disappearance in the light state can be suppressed.

According to a third aspect of the present invention, there is provided a lighting apparatus comprising: the discharge lamp lighting device according to the first or second aspect; and a reflector that reflects light emitted from the discharge lamp.

According to the present invention, the discharge lamp is turned on at a constant lamp power value corresponding to the dimming signal, and extinguishes even in a state where the lamp temperature is lowered or in a deep dimming state where the dimming ratio is around 0%. It is possible to provide an easy-to-use lighting fixture.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a circuit diagram of a discharge lamp lighting device according to a first embodiment of the present invention. In the figure, 1 is a discharge lamp lighting device, 2 is a DC power supply, 3 is a chopper circuit, 4 is an inverter circuit, 5 is a discharge lamp, 6 is a control circuit for a chopper circuit, 7 is a control circuit for an inverter circuit, and 8 is a multiplication circuit. , 9 is an amplifier circuit, 10 is a dimming control circuit, 11 is a dimmer, and 12 is a gain control circuit.

The input terminal of the rectifier DB1 is connected to the commercial AC power supply Vs, and the capacitor C1 is connected between the output terminals of the rectifier DB1 to constitute the DC power supply 2. The negative terminal of the capacitor C1 is connected to the ground E. The commercial AC voltage is rectified and smoothed by the rectifier DB1 and the capacitor C1, and a DC voltage is generated across the capacitor C1. The DC voltage generated at both ends of the capacitor C1 is input to the chopper circuit 3.

In the chopper circuit 3, a series circuit of an inductor L1 and a field effect transistor FET1 as a switching element is connected to both ends of a capacitor C1, and smoothed via a diode D1 connected to both ends of the field effect transistor FET1 in forward polarity. And the capacitor C2 for connection. The control electrode of the field effect transistor FET1 is connected to the chopper circuit control circuit 6. The control circuit 6 for the chopper circuit includes the field-effect transistor FET1
Are turned on and off at a predetermined switching frequency. When the field effect transistor FET1 turns on and off, the voltage across the capacitor C1 is choppered, and a boosted DC voltage is generated across the smoothing capacitor C2. The chopper circuit 3 functions as a second DC power supply. The DC voltage generated across the smoothing capacitor C2 is input to the inverter circuit 4.

The inverter circuit 4 includes a smoothing capacitor C
-Effect Transistor FET2 and Field-Effect Transistor FET Connected to Both Ends of Switch 2
3 and a drive circuit 13 having a power supply terminal connected to both ends of the smoothing capacitor C2. The output terminal of the drive circuit 13 is a field-effect transistor FET
2, and the input terminal is connected to the control circuit 7 for the inverter circuit. The drive circuit 13 is a field effect transistor F
ET2 and FET3 are alternately turned on and off. The control circuit 7 for the inverter circuit is a field effect transistor FET
2. The drive circuit 13 is controlled so that the FET 3 is alternately turned on and off at a predetermined frequency. When the field effect transistors FET2 and FET3 are turned on and off alternately, the field effect transistor F on the output side of the inverter circuit 4
A high frequency voltage is generated at both ends of ET3.

A series circuit of a DC cut capacitor C3, an inductor L2 as a current limiting element, and a fluorescent lamp 5 as a discharge lamp is connected to the output side of the inverter circuit 4, ie, both ends of the field effect transistor FET3. . Filament electrodes 5a and 5b of fluorescent lamp 5
Are connected to a secondary winding L2 provided on the inductor L2.
a, L2b are respectively connected to both ends. And
A starting capacitor C4 is connected between the inductor L2 and the fluorescent lamp 5 in parallel with the fluorescent lamp 5. When a high-frequency voltage is generated on the output side of the inverter circuit 4, the inductor L2 and the starting capacitor C4 resonate, and a resonance current flows through the inductor L2, and the secondary winding L2a,
A voltage is generated across L2b. This voltage is constantly applied to both ends of the filament electrodes 5a and 5b of the fluorescent lamp 5, and preheats the filament electrodes 5a and 5b. And
A resonance voltage is applied between the filament electrodes 5a and 5b, and the fluorescent lamp 5 is turned on. The fluorescent lamp 5 can be turned on with all light or dimming.

A series circuit of resistors R1 and R2 is connected in parallel with the fluorescent lamp 5, and a connection point a between the resistors R1 and R2 is connected to a multiplying circuit 8 as a lamp power calculating means. A resistor R3 is inserted between a connection point b between the filament electrode 5b and the secondary winding L2b and a connection point c between the starting capacitor C4 and the resistor R2. Is connected to the multiplication circuit 8 via The series circuit of the resistors R1 and R2 detects the lamp voltage value of the fluorescent lamp 5, and the resistor R3 detects the lamp current value of the fluorescent lamp 5. The multiplication circuit 8 receives the voltage across the resistor R2 correlated with the lamp voltage value and the voltage across the resistor R3 correlated with the lamp current value. The multiplying circuit 8 calculates a lamp power value by multiplying the lamp voltage value and the lamp current value, and outputs a control signal correlated with the lamp power value to the inverter circuit control circuit 7.

The dimming control circuit 10 is connected to the control circuit 7 for the inverter circuit. And the dimming control circuit 1
0 is connected to the dimmer 11. The dimmer 11 outputs a pulse-like dimming signal, and the dimming ratio of the fluorescent lamp 5 decreases as the ON width increases, that is,
The dimming state of the fluorescent lamp 5 is made deeper. When the dimming ratio is 100%, the fluorescent lamp 5 is in the all-light state, and when the dimming ratio is 0%, the fluorescent lamp 5 is in the off state. The dimming control circuit 10 converts the pulsed dimming signal into a control voltage and sends it to the inverter circuit control circuit 7. The dimmer 11 and the dimming control circuit 10 constitute a dimming signal output unit 14 and output a dimming signal for dimming and lighting the fluorescent lamp 5.

The dimming control circuit 10 is connected to a gain control circuit 12. The dimming control circuit 10 sends a control voltage equivalent to the control voltage sent to the inverter circuit control circuit 7 to the gain control circuit 12. That is, when a dimming signal is output such that the dimming ratio of the fluorescent lamp 5 is made lower (deepening the dimming state) than the dimmer 11, the dimming control circuit 10 sends out the dimming signal as the dimming ratio becomes lower. The applied control voltage increases almost in inverse proportion. Conversely, when a dimming signal that increases the dimming ratio of the fluorescent lamp 5 is output from the dimmer 11, the control voltage sent from the dimming control circuit 10 becomes almost inversely proportional as the dimming ratio increases. And decrease. On the other hand, the gain control circuit 12 outputs an amplification signal proportional to the control voltage from the dimming control circuit 10 to the amplification circuit 9. The amplification circuit 9 has a dimming ratio of the fluorescent lamp 5 of 100%.
In the (all light state), the resistance R input as the lamp current value
3 is directly output to the multiplication circuit 8 (amplification ratio: 1
As the dimming ratio becomes lower (the dimming state becomes deeper), the voltage across the input resistor R3 is amplified and output to the multiplying circuit 8 in accordance with the amplified signal. The voltage across the resistor R2 as a ramp voltage value is directly input to the multiplication circuit 8. Therefore, the lamp current value is varied according to the dimming signal output from the dimmer 11, and as the dimming ratio of the fluorescent lamp 5 decreases, the ratio of the lamp current value to the lamp voltage value increases, and the fluorescent lamp 5 As the dimming ratio of No. 5 increases, the ratio of the lamp current value to the lamp voltage value decreases. The resistance R
The series circuit of the resistor 1 and the resistor R2, the resistor R3, the amplifier 9 and the gain control circuit 12 constitute a detection value varying means 15. In the present embodiment, the detection value varying means 15 varies the detected lamp current value of the fluorescent lamp 5 according to the dimming signal.

Based on the lamp current value changed by the detection value changing means 15 and the lamp voltage value which is the voltage across the resistor R2, the multiplying circuit 8 as the lamp power calculation means calculates the lamp power value and controls the inverter circuit. 7 is output.

The inverter circuit control circuit 7 as a control circuit inputs a dimming signal from the dimming signal output means 14. That is, a pulse-like dimming signal corresponding to the dimming ratio of the fluorescent lamp 5 is output from the dimmer 11, and the pulse-like dimming signal is converted into a control voltage by the dimming control circuit 10 and is converted into an inverter circuit. Input to the control circuit 7.
The inverter circuit control circuit 7 switches the field effect transistors FET2 and FET3 of the inverter circuit 4 according to the control voltage input from the dimmer control circuit 10, that is, according to the dimming signal output from the dimmer 11. Vary the frequency. That is, as the dimming ratio of the fluorescent lamp 5 becomes lower (the dimming state becomes deeper), the inverter circuit control circuit 7 sets the field effect transistor FET
2, a control signal for increasing the switching frequency of the FET 3 is sent to the drive circuit 13, and the drive circuit 13 uses the field-effect transistors FET2 and FE based on the control signal.
T3 is alternately turned on and off. When the switching frequency of the field effect transistors FET2 and FET3 is varied, the output of the inverter circuit 4 is varied and the fluorescent lamp 5
Dimming.

The control circuit 7 for the inverter circuit receives the lamp power value calculated by the multiplication circuit 8 as the lamp power calculation means. Then, a control signal is sent to the drive circuit 13 of the inverter circuit 4 so as to have the lamp power value, and the drive circuit 13 alternately turns on and off the field effect transistors FET2 and FET3 based on the control signal.

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

When the commercial AC power supply Vs is turned on and the chopper circuit control circuit 6 and the inverter circuit control circuit 7 operate, high-frequency power is generated at both ends of the field effect transistor FET3, which is the output side of the inverter circuit 4, and fluorescent light is generated. The lamp 5 lights up.

The lamp voltage of the fluorescent lamp 5 is detected by a series circuit of a resistor R1 and a resistor R2, and the voltage across the resistor R2 is input to the multiplier 8 as a lamp voltage value. The lamp current of the fluorescent lamp 5 is detected by the resistor R3, and the voltage across the resistor R3 is input to the multiplication circuit 8 via the amplifier circuit 9 as the lamp current value. Initially, dimmer 11
When the dimming ratio of the dimming signal output from is 100% (the fluorescent lamp 5 is in the full light state), the amplification factor of the amplifier circuit 9 is 1 and the lamp current value detected by the resistor R3 is converted. Instead, it is directly input to the multiplication circuit 8. The multiplying circuit 8 calculates a lamp power value based on the input lamp voltage value and lamp current value, and outputs the calculated lamp power value to the inverter circuit control circuit 7.

When the ambient temperature of the fluorescent lamp 5 changes and the lamp temperature changes, the detected lamp voltage value and lamp current value change, and the lamp power value calculated by the multiplying circuit 8 also changes. When the lamp power value input from the multiplication circuit 8 changes, the inverter circuit control circuit 7 varies the switching frequency of the field effect transistors FET2 and FET3 of the inverter circuit 4 so that the reference lamp power value is set in advance. Thus, the fluorescent lamp 5 is turned on with a constant lamp power even when the lamp temperature changes, and a substantially constant brightness can be obtained from the fluorescent lamp 5. Note that the lamp power is stabilized at each dimming ratio according to the dimming signal output from the dimmer 11.

When a dimming signal for lowering the dimming ratio of the fluorescent lamp 5 is output from the dimmer 11, the inverter circuit control circuit 7 controls the field effect transistor F of the inverter circuit 4.
Increase the switching frequency of ET2 and FET3.
Then, the lamp current of the fluorescent lamp 5 decreases, and the fluorescent lamp 5 is turned on at a predetermined dimming ratio. In the fluorescent lamp 5, as the dimming ratio decreases, the lamp current decreases and the lamp voltage increases.

When the fluorescent lamp 5 is lit at a predetermined dimming ratio, the multiplication circuit 8 amplifies the voltage across the resistor R2 as a lamp voltage value and the voltage across the resistor R3 as a lamp current value by the amplifier circuit 9. The (variable) amplified voltage is input. This amplification factor is preset according to the dimming signal (or dimming ratio), and the amplification factor increases as the dimming ratio decreases. The gain of the amplifier circuit 9 is controlled by a control signal from the gain control circuit 12. As the dimming ratio of the fluorescent lamp 5 becomes lower (the dimming state becomes deeper), the lamp voltage rises, but the voltage across the resistor R3 is amplified beyond the rise. As a result, the ratio of the lamp current value to the lamp voltage value increases. The multiplying circuit 8 calculates a lamp power value based on the lamp voltage value and the changed lamp current value and outputs the calculated lamp power value to the inverter circuit control device 7. Inverter circuit control device 7
Determines the switching frequency of the field effect transistors FET2 and FET3 of the inverter circuit 4 in accordance with the difference between the lamp power value input from the multiplication circuit 8 and the reference lamp power value at a predetermined dimming ratio. Make it variable. That is, the difference is made to be zero. Since the lamp power value is set such that the ratio of the lamp current value to the lamp voltage value increases, the constant control of the lamp power value increases the specific gravity of the control for the lamp current value.

As the dimming signal for lowering the dimming ratio of the fluorescent lamp 5 (deepening the dimming state) is output from the dimmer 11, the control signal from the gain control circuit 12 increases the amplification factor of the amplifier circuit 9. Is controlled so as to increase the ratio of the lamp current value to the lamp voltage value. Thereby, the dimming ratio of the fluorescent lamp 5 is 100%.
In the (all light state), the inverter circuit 4 is controlled by constant power, and gradually becomes constant current control as the dimming ratio becomes lower (the dimming state becomes deeper), and the dimming ratio is close to 0%, for example, When it becomes 10% or less (deep lighting state), almost constant current control is performed. That is, the lamp voltage and the lamp current of the fluorescent lamp 5 are controlled such that the reference lamp power has a preset dimming ratio in the all-light lighting or the dimming lighting close to the all-light lighting. Then, in the deep dimming lighting in which the dimming ratio is close to 0%, the lamp current is almost controlled, and the reference lamp power is set to the preset dimming ratio. Therefore, the discharge lamp lighting device 1
Are as shown in FIG.

In FIG. 2, the slope of the load curve of the discharge lamp lighting device 1 increases from a curve A showing constant power characteristics at all light to a curve B showing constant current characteristics at deep dimming lighting. The current becomes even steeper, and the current becomes almost low at the time of deep dimming lighting. The characteristic curve B at the time of deep dimming lighting and the voltage-current curve (VI curve) C indicating the voltage-current characteristics of the fluorescent lamp 5 intersect at a large angle. Therefore, the lamp voltage rises due to a decrease in the ambient temperature of the fluorescent lamp 5, the lamp life, and the like, and the voltage-current curve of the fluorescent lamp 5 shifts from the VI curve C in the figure to the VI curve D shown by a broken line. Even so, the characteristic curve B and the VI curve D at the time of deep dimming lighting intersect, and the fluorescent lamp 5 keeps lighting and does not go out. In particular, when the fluorescent lamp 5 is a thin tube lamp, the lamp voltage at the time of dimming rises remarkably and the VI curve moves greatly, but the characteristic curve B at the time of deep dimming lighting is almost constant current characteristics. Since the curves form an intersection, no lamp extinguishment occurs.

As described above, since the inverter circuit control circuit 7 controls the inverter circuit 4 so as to have a preset lamp power value according to the dimming signal from the dimmer 11, the discharge lamp 5 Is turned on at a constant lamp power value, and a constant brightness is obtained from the discharge lamp 5. Also,
In the deep dimming state where the dimming ratio of the discharge lamp 5 is around 0%, the inverter circuit 4 is controlled almost at a constant current.
Even a discharge lamp having a small tube diameter does not cause the lamp to go out.

In the above-described embodiment, the detection value varying means 15 adjusts the ratio of the lamp current value to the lamp voltage value as the dimming ratio of the fluorescent lamp 5 decreases from 100% (all light state) to the dimming ratio. However, when the dimming ratio of the fluorescent lamp 5 becomes equal to or less than a predetermined level, for example, 30% or less, the ratio of the lamp current value to the lamp voltage value increases as the dimming ratio decreases. You may do so. For example, when the dimming signal output from the dimmer 11 is a dimming signal indicating a dimming ratio equal to or less than a predetermined level, the dimming control circuit 10 may send a control voltage to the gain control circuit 12. Good.

The inverter circuit 4 performs constant power control until the fluorescent lamp 5 is turned on at a predetermined level of dimming ratio, and performs constant current control as the dimming ratio becomes lower when the dimming ratio is lower than the predetermined level. Is done. Therefore, even at a dimming ratio equal to or less than a predetermined level at which the fluorescent lamp 5 is easily extinguished, the extinguishing of the fluorescent lamp 5 can be prevented.

In the above-described embodiment, the lamp current value input to the multiplication circuit 8 is amplified by the amplifier circuit 9 to increase the ratio of the lamp current value to the lamp voltage value. Instead, the lamp voltage value may be reduced in accordance with the dimming signal to increase the ratio of the lamp current value to the lamp voltage value. However, lowering the dimming ratio of the fluorescent lamp 5 (deeply dimming) means reducing the lamp current in accordance with the dimming ratio, and the lamp voltage increases as the lamp current decreases. Therefore, it is preferable that the lamp current is easier to control, and that the lamp current value be varied according to the dimming signal.

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

FIG. 3 is a schematic sectional view of a lighting fixture showing a second embodiment of the present invention.

The lighting fixture 16 shown in FIG. 3 is a direct-fitting lighting fixture, which comprises a lighting fixture main body 17, ring-shaped fluorescent lamps 18 and 19 having different tube lengths, a globe 20, and lighting devices 21 and 22 for discharge lamps. ing. Ring-shaped fluorescent lamp 18 having a short tube length and ring-shaped fluorescent lamp 1 having a long tube length
9 is concentrically attached to the lamp sockets 23 and 24 of the lighting fixture body 17. The lighting fixture body 17 includes a discharge lamp lighting device 2 from which the dimmer 11 and the fluorescent lamp 5 are removed from the discharge lamp lighting device 1 shown in FIG.
1 and 22 are built in and connected to ring-shaped fluorescent lamps 18 and 19. The dimmer 11 is attached to a wall (not shown). In addition, a reflector 25 that reflects light emitted from the ring-shaped fluorescent lamps 18 and 19 is attached to the lighting fixture body 17. The lighting fixture body 17
It is fixed to the ceiling 26 with screws (not shown) or the like, and the front surface is covered with the globe 20.

When a dimmer signal is output by operating a fader or the like of the dimmer 11, the ring-shaped fluorescent lamps 18, 19 change from all-light lighting to deep dimming to emit radiated light. Then, the emitted light becomes direct light and reflected light reflected by the reflector 25 and is emitted from the globe 20 on the front surface.

Since the annular discharge lamps 18 and 19 are lit at a constant lamp power value according to the dimming signal, a constant radiated light is radiated to obtain a constant brightness, and the lamp temperature is reduced. The ring-shaped fluorescent lamps 18 and 19 can be prevented from falling off even in a deeply dimmed state, and an easy-to-use lighting fixture 16 can be provided.

[0051]

According to the first aspect of the present invention, the control circuit comprises:
In addition to controlling the inverter circuit to have a lamp power value according to the dimming signal, and controlling the inverter circuit to be constant current control in the deep dimming state, the discharge lamp has a constant lamp power value according to the dimming signal. , And it can be prevented from disappearing even in a deep dimming state where the dimming ratio is around 0%.

According to the second aspect of the present invention, when the dimming ratio becomes equal to or less than a predetermined level at which the discharge lamp is easily extinguished, the control circuit performs the constant current control of the inverter circuit. It is possible to prevent the discharge lamp from extinguishing even in a deeply dimmed state.

According to the third aspect of the present invention, the discharge lamp is lit at a constant lamp power value according to the dimming signal, and is used in a state where the lamp temperature is lowered or a deep dimming state where the dimming ratio is around 0%. Can also prevent the discharge lamp from going out,
Easy-to-use lighting equipment can be provided.

[Brief description of the drawings]

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

FIG. 2 is a load curve diagram showing output characteristics.

FIG. 3 is a schematic cross-sectional view of a lighting fixture showing a second embodiment of the present invention.

FIG. 4 is a circuit diagram of a conventional discharge lamp lighting device.

FIG. 5 is a load curve diagram showing output characteristics.

FIG. 6 is also a load curve diagram in a deep region in a dimming state.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Discharge lamp lighting device 2 ... DC power supply 4 ... Inverter circuit 5 ... Fluorescent lamp as discharge lamp 7 ... Control circuit for inverter circuit as control circuit 8 ... Multiplier circuit 14 as lamp power calculation means 14 ... Dimming signal output means 15 ... Detection value variable means 16 ... Lighting equipment 25 ... Reflector

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K072 AA02 BA03 BA05 BB01 BC01 BC03 DB01 DC01 DD04 EB05 EB07 GA02 GB12 GC04 HA10 HB03 3K098 CC24 CC25 CC44 DD22 DD37 EE14 EE32 FF03 FF04 FF14 GG02

Claims (3)

[Claims] A direct-current power supply; an inverter circuit that receives the direct-current power supply and outputs high-frequency power; a discharge lamp that is connected to the inverter circuit and that can be turned on by all light or dimming; Dimming signal output means for outputting a dimming signal; detecting a lamp voltage value and a lamp current value of the discharge lamp, and increasing the ratio of the lamp current value to the lamp voltage value as the dimming ratio of the discharge lamp decreases. Detecting value varying means for varying at least one of a lamp voltage value and a lamp current value according to a dimming signal;
Lamp power calculating means for calculating a lamp power value based on a lamp voltage value and a lamp current value changed by a detected value changing means; a dimming signal input from a dimming signal output means, A control circuit for adjusting the output of the discharge lamp so as to dim the discharge lamp and controlling the inverter circuit so as to have a lamp power value calculated by the lamp power calculation means. . 2. The discharge device according to claim 1, wherein the detection value changing means changes at least one of a lamp voltage value and a lamp current value when the discharge lamp has a dimming ratio equal to or lower than a predetermined level. Lamp lighting device. 3. A lighting fixture comprising: the discharge lamp lighting device according to claim 1; and a reflector that reflects light emitted from the discharge lamp.