JPH05326181A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To perform a stable control against the fluctuation of load and power source by comparatively delaying response at the time of steady lighting, and accelerating the response at the time of a large load fluctuation such as the input of the power source or the lighting failure of a discharge lamp. CONSTITUTION:The drive signal of a MOS transistor(Tr) S1 for chopper switching is duty-controlled by the potential Vg of the G-point of a lamp voltage detecting circuit 2 which detects a lamp voltage Vd (D-point) at start and by the voltage Vh of the H-point of a chopper voltage detecting circuit 1 which detects a chopper voltage Va at lighting. Thus, stable control can be performed also to the fluctuation of a power source. When a discharge lamp fails in lighting, the voltage Vd is suddenly raised because of the sudden no-load state. Simultaneously, the potential Vg of the G-point is also raised, and the potential Vg exceeds the potential Vh of the H-point of the circuit 1 at a certain point of time. Since the drive signal of the TrSi is controlled by the detection signal of the voltage Vd, thereafter, ON-duty is reduced, and the potential Vg is settled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device having a chopper circuit on the power supply side.

[0002]

2. Description of the Related Art FIG. 6 is a circuit diagram of a conventional discharge lamp lighting device. The circuit configuration will be described below. The AC power supply Vs is connected to the AC input terminal of the full-wave rectifier DB. The inductor L is connected to the DC output terminal of the full-wave rectifier DB.
1 and the MOS transistor S1 are connected in series. A series circuit of capacitors C1 and C2 is connected to both ends of the MOS transistor S1 via a diode D1 for preventing backflow. The series circuit of the MOS transistors S2 and S3 is connected in parallel to the series circuit of the capacitors C1 and C2. Diodes D2 and D3 are connected in antiparallel to both ends of the MOS transistors S2 and S3, respectively. A connection point between the capacitors C1 and C2 and a MOS
A series circuit of an inductor L2 and a capacitor C3 is connected between the connection points of the transistors S2 and S3. A pulse transformer PT for starting is provided at both ends of the capacitor C3.
The discharge lamp LP is connected through the secondary winding of the. An igniter I is attached to the primary winding of the starting pulse transformer PT.
The output of G is connected.

Next, the structure of the circuit section for controlling the discharge lamp lighting device will be described. Capacitors C1 and C
The output voltage of the chopper generated in the series circuit of 2 is detected by dividing the potential Va at the point A by the resistors R1, R2, and R3, smoothed by the capacitor C4, and output as the voltage Vc at the point C of the error amplifier OP1. It is input to the inverting input terminal. The inverting input terminal of the error amplifier OP1 is connected to the level of the reference voltage Vref (= 5V) via the resistor R4, and is also grounded via the resistor R5. The output terminal of the error amplifier OP1 is connected to the inverting input terminal of the error amplifier OP1 via the diode D4 and the resistor R6. The cathode voltage of the diode D4 is P
It is inputted as a voltage for controlling the pulse width of the WM oscillation circuit 30. The oscillation output signal of this PWM oscillation circuit 30 is
It is amplified by the drive circuit 4 and input to the gate electrode of the MOS transistor S1.

The error amplifier OP1 and the PWM oscillation circuit 30 are composed of a general-purpose integrated circuit (IR3M02 manufactured by Sharp, hereinafter simply referred to as an IC), and the circuit configuration is shown in FIG.
However, the drive circuit 4 is provided outside the IC. This IC includes a reference voltage generation circuit 31, an oscillator 32,
PWM comparator 33, error amplifiers OP1 and OP2,
A pulse width modulation type switching regulator control circuit including a flip-flop circuit 34, a dead time comparator 35, an output circuit 36, and the like.
When the No. pin is set to the ground potential GND, the single end operation is performed, and when it is set to the potential of the control power supply Vcc, the push pull operation is performed. In this embodiment, since the single end operation is used, the output of the flip-flop circuit 34 for push-pull operation is ignored, and the output transistors Q1 and Q2 perform the same operation. The open emitter terminals (pins 9 and 10) of the transistors Q1 and Q2 are grounded, and the open collector terminals (8, 1)
Pin 1) is connected to the drive circuit 4. Between the power terminal (Pin 12) and the ground terminal (Pin 7),
The control power supply Vcc is applied, and the reference voltage generation circuit 3
1, the reference voltage Vr is applied to the reference voltage terminal (14th pin).
ef (= 5V) is obtained. The oscillator 32 has a frequency corresponding to the time constant of the capacitor Ct connected between the capacitor terminal (5th pin) and the ground terminal and the resistance Rt connected between the resistance terminal (6th pin) and the ground terminal. Generates a sawtooth wave signal. This signal is the PWM comparator 33
And is compared with the output of the error amplifier OP1.
In this embodiment, only one error amplifier OP1 is used,
The other error amplifier OP2 is not used. Pin 4 is a dead time control terminal, and 35 is a dead time comparator.

The operation of the above conventional example will be described below. The AC power supply Vs is full-wave rectified by the full-wave rectifier DB, and the input current of the AC power supply Vs is turned on by the MOS transistor S1.
In case of, full-wave rectifier DB, inductor L1, MOS
Energy flows through the path of the transistor S1 and the full-wave rectifier DB to store energy in the inductor L1. Also, MOS
When the transistor S1 is off, the full-wave rectifier D
B, inductor L1, diode D1, capacitor C
1 、 Capacitor C2 、 Full wave rectifier DB
The energy from the AC power source Vs and the energy stored in the inductor L1 are simultaneously stored in the capacitors C1 and C2.
Stored in. The MOS transistor S1 receives the oscillation output signal from the PWM oscillation circuit 30 of FIG.
Switching at 0 KHz. In this way, A
A DC voltage Va higher than the power supply voltage is obtained at the point. A booster chopper circuit is configured by the above circuits.

Next, the operation of the lighting circuit of the discharge lamp LP will be described. First, while one MOS transistor S2 is switching at a high frequency, the other MOS transistor S3 is OFF and the MOS transistor S2
When 2 is turned on, the current is a capacitor C1, a MOS transistor S2, an inductor L2, a pulse transformer P.
T, discharge lamp LP, capacitor C1 flow, MOS
When the transistor S2 is turned off, the inductor L
The energy stored in 2 is discharged through the path of the inductor L2, the pulse transformer PT, the discharge lamp LP, the capacitor C2, the diode D3, and the inductor L2. Then M
During the period when the OS transistor S3 is switching at high frequency, the MOS transistor S2 is OFF, and M
When the OS transistor S3 is turned on, the current flows through the path of the capacitor C2, the discharge lamp LP, the pulse transformer PT, the inductor L2, the MOS transistor S3, and the capacitor C2, and when the MOS transistor S3 is turned off, it is stored in the inductor L2. Energy is released through the path of the inductor L2, the diode D2, the capacitor C1, the discharge lamp LP, the pulse transformer PT, and the inductor L2. Hereinafter, the same process is repeated, and the discharge lamp LP
A rectangular wave current as shown in FIG. The circuit described above constitutes a half-bridge type rectangular wave lighting circuit.

Next, the chopper voltage detection circuit 1 and the chopper control circuit 3 for controlling the step-up chopper circuit.
The operation will be described. FIG. 9 shows the main configuration of the chopper voltage detection circuit 1 and the chopper control circuit 3.
First, the potential Va at the point A output from the step-up chopper circuit CHP is divided by the resistors R1, R2, and R3, and the divided voltage is smoothed by the capacitor C4, so that the output voltage of the chopper voltage detection circuit 1 is C. The potential Vc at the point is obtained. The potential Vc at the point C is input to the non-inverting input terminal of the error amplifier OP1 in the chopper control circuit 3.
This terminal corresponds to the 1st pin of the IC shown in FIG. Hereinafter, description will be given while showing specific circuit constants. The error amplifier OP1 is used as a differential amplifier circuit that performs a negative feedback operation. Error amplifier OP1 inverting input terminal (IC 2
The reference voltage Vref (= 5V) to the resistor R4.
The potential Vb at the point B divided by (= 5 KΩ) and R5 (= 5 KΩ) is applied, and its value is about 2.5V. Here, the inverting input terminal and the non-inverting input terminal of the error amplifier OP1 are in a virtual short circuit (imaginary short) state, and the potential Vc at the point C becomes equal to the potential Vb at the point B. The potential Vc becomes approximately 2.5V. However,
The constants of the resistors R1 to R3 are selected so that the potential Vc at the point C is 2.5V when the potential Va at the point A is 400V. When the potential Vc at the point C rises with respect to the potential Vb at the point B, the difference between the potential Vc at the point C and the potential Vb at the point B increases, so the potential of the third pin output from the error amplifier OP1 rises. .. On the contrary, when the potential Vc at the point C decreases with respect to the potential Vb at the point B, the potential Vc at the point C and the potential V at the point B
Since the difference of b becomes small, the potential of the third pin output from the error amplifier OP1 drops. That is, the potential of the third pin of the IC shown in FIG. 7 is a value obtained by amplifying the difference between the potential Vb at the point B and the potential Vc at the point C.

Next, the PW in the chopper control circuit 3
The configuration of the M control unit is shown in FIG. This circuit is also provided inside the IC as shown in FIG. Error amplifier OP
The PWM comparator 33 outputs the output signal of the No. 3 pin of the IC output from 1 and the sawtooth wave output from the oscillator 32.
In comparison, the drive signal of the MOS transistor S1 is designed to be High level while the sawtooth wave is higher, and is set to Low level when the sawtooth wave is lower. The time charts are shown in FIGS. 11 and 12. In the figure, Vn is a sawtooth wave output from the oscillator 32, V3 is an output signal of the third pin of the IC output from the error amplifier OP1, Vn
Reference numeral 4 is a dead time control signal input to the dead time comparator 35. The dead time control signal V4 is a constant voltage, and the higher one of the output signal V3 of the third pin of the IC and the dead time control signal V4 has priority, and the signal gives the duty of the drive signal of the MOS transistor S1. decide.

Immediately after starting, the output signal V3 of the 3rd pin of the IC
Is almost 0V, and is naturally lower than the dead time control signal V4. Therefore, as shown in FIG. 11, the dead time control signal V4 causes the MOS
The duty of the drive signal of the transistor S1 is determined, and the output voltage Va of the chopper rises. When the output voltage Va of the chopper rises, the output signal V3 of the 3rd pin of the IC also rises, and the dead time control signal V
Higher than 4. After that, as shown in FIG.
The duty of the drive signal of the MOS transistor S1 is determined by the output signal V3 of the third pin of the IC. on the other hand,
The higher the output voltage Va of the chopper, the more the IC
Although the voltage of the third pin also increases, the on-duty of the drive signal of the MOS transistor S1 decreases accordingly, and the increase of the voltage Va converges to a certain constant value. In FIG. 9, the potential Vc at the point C is approximately 2.5 V, and R1 = 7
Since 20 KΩ, R2 = 75 KΩ, and R3 = 5 KΩ, the convergence value of the output voltage Va of the chopper is 2.5 V × (R3 +
R2 + R1) /R3=2.5× (720 + 75 + 5) /
5 = 400V. However, for fine adjustment, use the variable resistor R
I will do it in 2. Once the output voltage Va of the chopper converges to 400V, it will be 40% for some reason.
When it fluctuates to 0 V or more, the potential Vc at the point C rises, and at the same time, the output signal V3 of the 3rd pin of the IC also rises. Therefore,
Since the on-duty of the drive signal of the MOS transistor S1 decreases, the output voltage Va of the chopper begins to decrease,
It converges to 400V again. Even when the voltage Va fluctuates to 400 V or less, it converges to 400 V again.

The capacitor C4 in FIG. 9 is for smoothing the voltage obtained by dividing the potential Va at the point A, that is, the potential Vc at the point C. The larger the capacitance, the higher the potential Vc at the point C. Since it changes slowly, the detection speed of the output voltage Va of the chopper becomes slower as a result. As described above, in the above-mentioned conventional example, the chopper voltage detection circuit 1 and the chopper control circuit 3 feedback-control the on-duty of the switching MOS transistor S1 in the step-up chopper circuit. Va is converged to a constant voltage.

[0011]

In the above conventional example, the smaller the capacitance of the capacitor C4 shown in FIG. 9, the faster the detection speed of the output voltage Va of the chopper becomes,
Therefore, when the voltage Va changes, it is sensed and the MOS transistor S for switching the chopper is detected.
The time until the on-duty of 1 is changed becomes short. However, in the case of such a conventional discharge lamp lighting device, if the capacitance of the capacitor C4 is reduced and the detection speed of the output voltage Va of the chopper is increased, when the load is relatively light with respect to the input power, for example, the power supply There is a problem that the input current becomes vertically asymmetric when the voltage is higher than the rating and the output current is small. On the contrary, when the capacitance of the capacitor C4 is increased and the detection speed of the output voltage Va of the chopper is slowed, the output voltage Va of the chopper overshoots at the time of a sudden load change such as when the power switch is turned on or when the discharge lamp goes out. However, the voltage exceeds the set value, which is a problem in the withstand voltage of parts.

The reason why the input current becomes vertically asymmetric when the detection speed of the output voltage Va of the chopper is increased will be described. As shown in FIG. 13, the period T1 in which the drive signal of the MOS transistor S1 is small and the period T2 in which the drive signal of the MOS transistor S1 is large are alternately repeated. Instead of suddenly switching to, it will gradually change. Then, when the on-duty is large, a large current flows into the chopper circuit,
Apparently, the input current increases. Therefore, when compared with the sine wave shown by the broken line in FIG. 13, the input current has a vertically asymmetrical current waveform as shown by the solid line.

On the other hand, the reason why the voltage Va overshoots when the detection speed of the output voltage Va of the chopper is slowed is that the voltage Va rises when the power is turned on and immediately after the voltage Va reaches a predetermined voltage, the MOS transistor S1 This is because the operation of reducing the on-duty of the drive signal is delayed, so that the voltage Va starts to drop after the voltage exceeds a predetermined voltage and overshoots to some extent. Further, even if the output voltage Va of the chopper begins to rise when the load suddenly becomes light, such as when the discharge lamp LP is extinguished, the control of the drive signal of the MOS transistor S1 against it will be delayed and overshoot will occur. I will end up.

The present invention has been made in view of the above points, and an object of the present invention is to stabilize a discharge lamp lighting device having a chopper circuit on the power supply side against variations in load and power supply. It is to enable the controlled.

[0015]

In the discharge lamp lighting device of the present invention, in order to solve the above-mentioned problems, in the output voltage control of the chopper circuit which is the power source of the discharge lamp lighting circuit, during steady lighting, It is characterized in that the response speed is made relatively slow, and the response speed is made fast in the case of large load fluctuations such as when the power is turned on or when the discharge lamp goes out. In other words, during steady lighting, the output voltage of the chopper circuit is detected as usual, the switching element of the chopper circuit is controlled based on the detected voltage, and the response speed is set relatively slow. When the discharge lamp is started or extinguished, the switching element of the chopper circuit is controlled by the detection signal of the lamp voltage of the discharge lamp, which has a faster response speed than the output voltage of the chopper circuit.

[0016]

According to the present invention, the first detection circuit for detecting the voltage of the DC power source composed of the chopper circuit and the second detection circuit for detecting the voltage of the discharge lamp are provided, and the response speed is relatively high at the time of steady lighting. Since the chopper circuit is controlled by the detection signal from the first detection circuit whose speed is slow, it is possible to prevent the asymmetry of the input current waveform due to power supply fluctuation and the like. On the other hand, the control at the moment when the load becomes light, such as when the power is turned on or when the discharge lamp goes out, controls the chopper circuit by the detection signal from the second detection circuit, which has a relatively high response speed. The output voltage of the chopper circuit can be stably controlled even with a sharp change in When the discharge lamp is turned on, the detection signal from the second detection circuit sharply decreases, so switching from the second detection circuit to the first detection circuit is performed.

[0017]

FIG. 1 is a circuit diagram of an embodiment of the present invention. The same components as those of the conventional example shown in FIG. 6 are designated by the same reference numerals, and redundant description will be omitted. In this embodiment, the connection point D between the inductor L2 and the capacitor C3 in the discharge lamp lighting circuit
Is applied to the series circuit of the resistors R7, R8 and R9 via the DC cut capacitor C5. A rectifying diode D8 is connected to both ends of the resistor R9 with the illustrated polarity, and a voltage generated at both ends of the resistor R9 is charged in the capacitor C6 via the backflow blocking diode D7. A high resistance R10 for discharging the charged electric charge is connected in parallel to both ends of the capacitor C6. The lamp voltage detection circuit 2 is configured as described above, and the lamp voltage Vd is detected as the potential Vg at the point G. The potential Vg at the point G is applied to the non-inverting input terminal of the error amplifier OP1 via the diode D6. Further, similarly to the conventional example of FIG. 6, the chopper output voltage Va obtained at the point A is detected as the potential Vh at the point H by the chopper voltage detection circuit 1, and the potential Vh at the point H is erroneous via the diode D5. It is applied to the non-inverting input terminal of the amplifier OP1. The diodes D6 and D5 form an OR circuit, and the potential Vg at the point G where the lamp voltage detection circuit 2 detects the lamp voltage Vd and the potential at the point H when the chopper voltage detection circuit 1 detects the output voltage Va of the chopper. The higher voltage of Vh controls the on-duty of the MOS transistor S1 for switching the chopper.

The operation of this embodiment will be described below.
First, the operation of the lamp voltage detection circuit 2 will be described. 2 and 3 show voltage waveforms Vd, Ve, Vf and Vg at points D, E, F and G in the circuit of FIG.
FIG. 2 is a voltage waveform in a lighting state of the discharge lamp.
Is a voltage waveform in an unloaded state. Since there is no load at the time of starting and when the discharge lamp goes out, the voltage across the capacitor C1 or C2 (that is, 200 V) is detected.
In the circuit of FIG. 1, the constants of the resistors R7, R8 and R9 are D
When the potential Vd at the point is 200V, the potential Vg at the point G is 2.
Selected to be 5V, R7 = 320KΩ, R8
= 75 KΩ and R9 = 5 KΩ. As a result, assuming that the lamp voltage during lighting is 80 V, the potential Vg at the point G when this is detected is 80 × 5 / (320 + 75 + 5)
= 1.0 (V).

Further, in the chopper voltage detection circuit 1 for detecting the output voltage Va of the chopper, as described above, the resistance R1 is set so that the potential Vh at the H point becomes 2.5V when the potential Va at the A point is 400V. , R2, R3 constants are determined. On the other hand, since capacitors C6 (= 1 μF) and C4 (= 10 μF) having different capacitances are connected to the points G and H, respectively, the potential Vd at the points D, A, G, and H just after the start, Va, Vg, and Vh change as shown in FIG. Since the diodes D6 and D5 form an OR circuit, the non-inverting input terminal of the error amplifier OP1 has G
Since the higher one of the potential Vg at the point and the potential Vh at the point H is input, the potential Vg at the point G at which the lamp voltage Vd is detected is input at times t0 to t3 as shown in FIG. 4B. ,
After time t5, H when the output voltage Va of the chopper is detected
The point potential Vh is input. Therefore, at the times t0 to t3, the detection speed of the chopper voltage Va becomes faster, and the overshoot is suppressed as much as possible. This is because the capacitor C6 (= 1 μF) having a small capacitance is connected to the point G. Further, after time t5 after the discharge lamp is turned on, the detection speed of the chopper voltage Va becomes slow, so that it is possible to prevent the input current from becoming asymmetrical in the vertical direction. This is because the capacitor C4 (= 10 μF) having a large capacitance is connected to the point H.

At time t0, the power switch is turned on, and at time t
At 1, the chopper voltage Va (potential at point A) reaches 400V and the lamp voltage Vd (potential at point D) reaches 200V. However, the potential Vg at the point G where the lamp voltage Vd is detected
Has not reached 2.5 V at this point, the chopper voltage Va (potential at point A) and the lamp voltage Vd (potential at point D) overshoot as shown in FIG.
After that, at time t2, the potential Vg at the point G at which the lamp voltage Vd is detected reaches 2.5 V, so that the overshoot subsides. At this time, the detection voltage of the chopper voltage Va (potential V at the H point is applied to the non-inverting input terminal of the error amplifier OP1).
If h) is input, the chopper voltage Va and the lamp voltage Vd will overshoot until time t3, as shown by the two-dot chain line and the one-dot chain line in FIG. From time t3 to t5, H when the chopper voltage Va is detected
The potential Vh at the point becomes equal to the potential Vg at the point G where the lamp voltage Vd is detected. On the other hand, if it is assumed that the discharge lamp starts lighting at time t4, the lamp voltage Vd instantaneously becomes 0 V and then gradually increases. At that time, the potential Vg at the point G where the lamp voltage Vd is detected drops from time t5 as shown in FIG. 4B after a certain time after the start of discharge. However, t5-t4 = t2-t1. After time t5,
The potential Vh at the H point where the chopper voltage Va is detected becomes higher and is input to the non-inverting input terminal of the error amplifier OP1. With the above-described mechanism, the drive signal of the MOS transistor S1 for switching the chopper is controlled by the potential Vg at the point G detecting the lamp voltage Vd at the time of starting and the potential Vh at the point H detecting the chopper voltage Va at the time of lighting. In the discharge lamp lighting device having a chopper circuit on the power supply side,
It is possible to perform stable control even when the power supply fluctuates.

Next, the operation when the discharge lamp goes out will be described with reference to FIG. If the discharge lamp is extinguished at time t6, the load voltage suddenly becomes no load.
It sharply rises as shown by the solid line in FIG. At the same time, the potential Vg at the point G as a detection signal of the lamp voltage Vd
Also rises as shown in FIG. 5B, and at a certain point in time from t6 to t7, the potential V at the point G as the detection signal of the lamp voltage Vd.
g exceeds the potential Vh at the point H as a detection signal of the chopper voltage Va, and thereafter, the drive signal of the MOS transistor S1 is controlled by the detection signal of the lamp voltage Vd, so that the on-duty decreases and the The output voltage Va settles at 400 V at time t8. As a result, stable control can be performed even when the load changes.

[0022]

According to the present invention, in a discharge lamp lighting device in which a DC power supply is formed by a chopper circuit and a discharge lamp is connected to the output end of this DC power supply through at least a current limiting element, A first detection circuit for detecting the voltage of the DC power supply for controlling the switching element;
The higher output signal of the second detection circuit for detecting the voltage of the discharge lamp is used, and the response speed of the output signal of the second detection circuit is the response speed of the output signal of the first detection circuit at least during a sudden load change. Since the output signal of the second detection circuit is set smaller than that of the first detection circuit during steady lighting, the response speed for chopper control during steady lighting is slow and the input speed is low. The inconvenience that the current becomes asymmetric does not occur. Further, since the response speed for controlling the chopper becomes fast when the load changes abruptly, the chopper output voltage does not become excessive, and it is possible to prevent stress from being applied to the circuit components.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is an operation waveform diagram at the time of lighting according to an embodiment of the present invention.

FIG. 3 is an operation waveform diagram under no load according to an embodiment of the present invention.

FIG. 4 is an operation waveform diagram when the power is turned on in the embodiment of the present invention.

FIG. 5 is an operation waveform diagram when the discharge lamp is extinguished according to the embodiment of the present invention.

FIG. 6 is a circuit diagram of a conventional example.

FIG. 7 is a circuit diagram of a switching regulator control IC used in a conventional example.

FIG. 8 is a waveform diagram showing a lamp current waveform in a conventional example.

FIG. 9 is a circuit diagram of a chopper voltage detection circuit and a chopper control circuit of a conventional example.

FIG. 10 is a circuit diagram of main parts of a conventional chopper control circuit.

FIG. 11 is an operation waveform diagram of the conventional chopper control circuit when the power is turned on.

FIG. 12 is an operation waveform diagram of a conventional chopper control circuit during steady lighting.

FIG. 13 is a waveform diagram for explaining the cause of the asymmetry of the input current in the conventional example.

[Explanation of symbols]

 1 Chopper voltage detection circuit 2 Lamp voltage detection circuit 3 Chopper control circuit LP discharge lamp

Claims (1)

[Claims] 1. A DC power supply is formed by a chopper circuit including at least a switching element, an inductance element, a capacitor, and a rectifier, and an output end of the DC power supply,
In a device in which a discharge lamp lighting circuit including at least a current limiting element and a discharge lamp is connected, a first detection circuit for detecting the voltage of the DC power supply and a second detection circuit for detecting the voltage of the discharge lamp.
And a means for controlling the switching element of the DC power supply by using the higher one of the output signals of the first detection circuit and the second detection circuit, and the second detection circuit at least when the load suddenly changes. Is configured so that the response speed of the output signal of is faster than the response speed of the output signal of the first detection circuit, and during steady lighting, the output signal of the second detection circuit is smaller than that of the first detection circuit. A discharge lamp lighting device having the above-mentioned configuration.