JP2009129554A - Discharge lamp lighting device and lighting fixture - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately detect abnormal lighting of a discharge lamp lighting device, equipped with a light control function, due to end of life or the like of a discharge lamp. <P>SOLUTION: Based on a light control level decided by a light-control determination part 151, a frequency of high-frequency alternating current voltage is decided for a frequency directing part 152 to be applied on a load circuit. A detection level directing part 153 decides a detection level of an abnormality detection voltage an abnormality detection circuit 170 generates based on the light control level. When an abnormality detection voltage the abnormality detection circuit 170 generates based on the detection level decided is higher than a detected threshold value voltage, an oscillation stoppage directing part 154 stops generation of high-frequency voltage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a discharge lamp lighting device for lighting a discharge lamp.

If the discharge lamp is abnormally lit due to the end of its life, etc., it is necessary to turn off the discharge lamp immediately for safety. For this reason, there is a technique for detecting abnormal lighting of the discharge lamp by detecting a voltage rise that occurs when the discharge lamp abnormally lights.
On the other hand, there is a discharge lamp lighting device having a dimming function for adjusting the brightness of the discharge lamp by changing the voltage applied to the discharge lamp. This is a function desired from the viewpoint of energy saving and lighting production in house lighting and facility lighting.
JP-A-5-144588 JP 2005-50649 A

In a discharge lamp lighting device having a dimming function, the voltage applied to the discharge lamp is changed, and this should not be erroneously detected as an abnormality of the discharge lamp.
The present invention has been made to solve the above-described problems, for example, and accurately detects abnormal lighting of a discharge lamp without erroneously determining a voltage fluctuation due to dimming as an abnormality of the discharge lamp. With the goal.

The discharge lamp lighting circuit according to this invention is
A load circuit in which a choke coil, a coupling capacitor, and a discharge lamp circuit are electrically connected in series;
An inverter circuit for generating an alternating voltage to be applied to the load circuit;
Based on the potential at one end of the discharge lamp circuit, an abnormality detection circuit that detects the amplitude of the potential at one end of the discharge lamp circuit and generates an abnormality detection voltage proportional to the detected amplitude;
A microcomputer for controlling the inverter circuit,
The discharge lamp circuit has a discharge lamp connecting portion that can be electrically connected to the discharge lamp, and a starting capacitor that is electrically connected in parallel with the discharge lamp when the discharge lamp is electrically connected to the discharge lamp connecting portion.
The microcomputer is
A dimming determination unit for determining the brightness for lighting the discharge lamp electrically connected to the discharge lamp connection unit;
The frequency of the AC voltage generated by the inverter circuit is determined based on the brightness determined by the dimming determination unit, and the inverter circuit is instructed to generate the AC voltage based on the determined frequency. A frequency indicator;
Based on the brightness determined by the dimming determination unit, a ratio between the amplitude detected by the abnormality detection circuit and the abnormality detection voltage generated by the abnormality detection circuit is determined, and the abnormality detection voltage is determined based on the determined ratio. A detection level instruction unit for instructing the abnormality detection circuit to generate
Based on the abnormality detection voltage generated by the abnormality detection circuit, an oscillation stop instruction that instructs the inverter circuit to stop generating the AC voltage when the abnormality detection voltage is higher than a predetermined detection threshold voltage Part.

  According to the discharge lamp lighting device of the present invention, the ratio between the amplitude detected by the abnormality detection circuit and the abnormality detection voltage generated by the abnormality detection circuit based on the brightness of lighting the discharge lamp determined by the dimming determination unit. Therefore, even if the voltage applied to the discharge lamp changes due to dimming, the abnormality of the discharge lamp can be detected with high accuracy. There is an effect.

Embodiment 1 FIG.
The first embodiment will be described with reference to FIGS.

FIG. 1 is a perspective view showing an external appearance of a lighting fixture 800 in this embodiment.
The lighting fixture 800 has a discharge lamp socket 810 to which the discharge lamp LA can be detachably attached, and lights the discharge lamp LA attached to the discharge lamp socket 810.
The lighting fixture 800 has the discharge lamp lighting device 100 (not shown) inside.
The discharge lamp lighting device 100 receives a low-frequency AC voltage (for example, 50 Hz or 60 Hz, 100 V to 242 V) from an AC power source AC such as a commercial power source, and generates a high-frequency AC voltage (for example, 45 kHz) to be applied to the discharge lamp LA.

FIG. 2 is an electric circuit diagram showing a circuit configuration of the discharge lamp lighting device 100 according to this embodiment.
The discharge lamp lighting device 100 includes a power rectifier circuit 110, an active filter circuit 120, an inverter circuit 130, a load circuit 140, a microcomputer 150, and an abnormality detection circuit 170.

The power supply rectifier circuit 110 generates a pulsating voltage by full-wave rectifying the AC voltage input from the AC power supply AC. The power rectifier circuit 110 is, for example, a diode bridge DB.
The power supply rectifier circuit 110 may include a common mode choke, a normal mode choke, an across the line capacitor, and the like for removing noise.

  The active filter circuit 120 boosts or steps down the pulsating voltage generated by the power supply rectifier circuit 110 to generate a high DC voltage (eg, 440 V). The active filter circuit 120 is, for example, a step-up chopper circuit that includes a choke coil L21, PFC 122, FET Q23, diode D24, and capacitor C25. To improve.

The inverter circuit 130 generates a high frequency AC voltage from the DC voltage generated by the active filter circuit 120.
The inverter circuit 130 includes, for example, an FET Q31, an FET Q32, and an inverter control circuit 133.
The FET Q31 and the FET Q32 are electrically connected in series to the output of the active filter circuit 120.
The inverter control circuit 133 outputs a drive signal for turning on and off the FET Q31 and the FET Q32 based on an instruction from the microcomputer 150.
When generating a high-frequency AC voltage according to an instruction from the microcomputer 150, the inverter control circuit 133 generates a drive signal for alternately turning on and off the FET Q31 and the FET Q32 at the instructed frequency. As a result, a high-frequency rectangular wave voltage of the instructed frequency is generated at the connection point between the FET Q31 and the FET Q32.
In addition, when the generation of the high-frequency AC voltage is stopped by an instruction from the microcomputer 150, the inverter control circuit 133 generates a drive signal that keeps both the FET Q31 and the FET Q32 off. As a result, no voltage is generated at the connection point between the FET Q31 and the FET Q32.

The high frequency AC voltage generated by the inverter circuit 130 is applied to the load circuit 140. Thereby, the discharge lamp LA attached to the discharge lamp socket 810 is turned on.
The load circuit 140 is a circuit in which a choke coil L41, a coupling capacitor C42, and a discharge lamp circuit 143 are electrically connected in series.
The choke coil L41 is an inductor for limiting the current flowing through the discharge lamp LA when the discharge lamp LA is lit.
The coupling capacitor C42 is a capacitor for cutting the DC component of the high-frequency AC voltage generated by the inverter circuit 130.
In this example, the choke coil L41, the discharge lamp circuit 143, and the coupling capacitor C42 are connected in series, but the connection order is not limited to this. For example, the choke coil L41, the coupling capacitor C42, and the discharge lamp circuit 143 are connected. The order may be as follows.

The discharge lamp circuit 143 includes a starting capacitor C44 and a discharge lamp connection portion 145.
The discharge lamp connection unit 145 is a contact point that is electrically connected to the discharge lamp LA attached to the discharge lamp socket 810.
The starting capacitor C44 is electrically connected in parallel with the discharge lamp LA when the discharge lamp LA is electrically connected to the discharge lamp connection portion 145. The starting capacitor C44 is a capacitor for generating a high voltage to be applied to the discharge lamp LA at the start by resonance with the choke coil L41.

  The microcomputer 150 controls lighting, dimming, and extinguishing of the discharge lamp LA by giving an instruction to the inverter circuit 130, the abnormality detection circuit 170, and the like. Detailed operation of the microcomputer 150 will be described later.

The operation input circuit 160 inputs a user's operation and outputs a signal representing the content of the input operation (hereinafter referred to as “operation signal”) to the microcomputer 150.
The operation input circuit 160 includes, for example, a pull string, an operation panel, a remote control light receiving circuit, and the like. The user pulls the pull string, the user operates a button provided on the operation panel, or switches the remote control. When the user presses, the operation content operated by the user is input.

The abnormality detection circuit 170 generates an abnormality detection voltage in order for the microcomputer 150 to detect abnormal lighting of the discharge lamp LA attached to the discharge lamp socket 810.
The abnormality detection circuit 170 receives the potential of the terminal on the high potential side (hereinafter referred to as “detection point”) of the discharge lamp circuit 143, and detects the amplitude of the potential of the input detection point. Here, the amplitude of the potential at the detection point is the difference (PP voltage) between the maximum value and the minimum value of the potential at the detection point. The abnormality detection circuit 170 generates a voltage proportional to the detected amplitude and sets it as an abnormality detection voltage.
For example, when the discharge lamp LA reaches the end of its life, the impedance of the discharge lamp LA increases and the amplitude of the potential at the detection point increases. Therefore, the abnormality detection voltage generated by the abnormality detection circuit 170 is increased.

  FIG. 3 is a detailed block diagram showing the configuration of internal blocks of the microcomputer 150 and the abnormality detection circuit 170 in this embodiment.

The microcomputer 150 implements the functional blocks described below by executing a program stored in a storage device such as a ROM (not shown).
The microcomputer 150 includes a dimming determination unit 151, a frequency instruction unit 152, a detection level instruction unit 153, and an oscillation stop instruction unit 154.

  The dimming determination unit 151 determines the brightness (hereinafter referred to as “the dimming level”) for lighting the discharge lamp LA attached to the discharge lamp socket 810. For example, the dimming determination unit 151 receives a signal representing the user's operation content output from the operation input circuit 160, and determines a dimming level corresponding to the user's dimming operation based on the input signal. . Alternatively, the dimming determination unit 151 darkens the discharge lamp LA when the outdoor is bright, and brightens the discharge lamp LA when the outdoor is dark, based on an input from a sensor that detects outdoor brightness. The dimming level may be determined. In addition, the dimming determination unit 151 measures the cumulative lighting time of the discharge lamp LA, darkens the discharge lamp LA when the cumulative lighting time is short, and brightens the discharge lamp LA when the cumulative lighting time is long. The dimming level may be determined.

The frequency instruction unit 152 determines the frequency of the high-frequency AC voltage generated by the inverter circuit 130 and instructs the inverter control circuit 133 to generate the high-frequency AC voltage having the determined frequency. For example, the frequency instruction unit 152 generates and outputs a frequency instruction signal representing the determined frequency. The inverter control circuit 133 receives the frequency instruction signal output from the frequency instruction unit 152 and determines the frequency of the drive signal to be generated based on the input frequency instruction signal.
When starting the lighting of the discharge lamp LA, the frequency instruction unit 152 first sets the frequency for preheating the discharge lamp LA (hereinafter referred to as “preheating frequency”) to the frequency of the high-frequency AC voltage generated by the inverter circuit 130. To decide. The preheating frequency is a frequency away from the resonance frequency of the choke coil L41 and the starting capacitor C44. When the inverter circuit 130 generates a high frequency AC voltage having the preheating frequency, a relatively low voltage is generated between the filaments of the discharge lamp LA. Applied. Thereby, the filament of the discharge lamp LA is warmed and it becomes easy to start discharge.
After the time that the filament of the discharge lamp LA is sufficiently warmed up, the frequency indicating unit 152 generates a frequency (hereinafter referred to as “starting frequency”) for starting the discharge of the discharge lamp LA by the inverter circuit 130. Determine the frequency of the high-frequency AC voltage. The starting frequency is a frequency close to the resonance frequency of the choke coil L41 and the starting capacitor C44. When the inverter circuit 130 generates a high-frequency AC voltage having the starting frequency, a relatively high voltage is applied between the filaments of the discharge lamp LA. Is done. Since the filament of the discharge lamp LA is sufficiently warmed, the discharge between the filaments of the discharge lamp LA starts and the discharge lamp LA is lit.
After the discharge lamp LA is lit, the frequency instruction unit 152 determines the frequency for continuing the lighting of the discharge lamp LA (hereinafter referred to as “lighting frequency”) as the frequency of the high-frequency AC voltage generated by the inverter circuit 130. To do. The lighting frequency may be the same as or different from the preheating frequency.
When the discharge lamp LA is lit, the voltage applied to the discharge lamp LA is determined by the lighting frequency. The higher the lighting frequency, the lower the voltage applied to the discharge lamp LA, and the lower the lighting frequency, the discharge lamp LA. The voltage applied to becomes higher. Since the lit discharge lamp LA has a negative resistance, the higher the voltage applied to the discharge lamp LA, the smaller the current flowing through the discharge lamp LA. For this reason, the light control level can be changed by changing the lighting frequency.
The frequency instruction unit 152 determines the lighting frequency based on the dimming level determined by the dimming determination unit 151 and instructs the inverter control circuit 133 to generate a high-frequency AC voltage of the determined lighting frequency.

  The oscillation stop instruction unit 154 receives the abnormality detection voltage generated by the abnormality detection circuit 170, and compares the input abnormality detection voltage with a predetermined detection threshold voltage. As a result of the comparison, when it is determined that the abnormality detection voltage is higher than the predetermined detection threshold voltage, the oscillation stop instruction unit 154 instructs the inverter control circuit 133 to stop the generation of the high-frequency AC voltage. For example, the oscillation stop instruction unit 154 generates and outputs an oscillation stop signal that instructs to stop the generation of the high-frequency AC voltage. The inverter control circuit 133 receives the oscillation stop signal output from the oscillation stop instruction unit 154, and stops the generation of the high-frequency AC voltage based on the input transmission stop signal.

Some microcomputers have built-in analog-digital converters and can compare the input voltage with an arbitrary threshold voltage. However, the microcomputer 150 in this embodiment does not have any built-in analog-digital converter. To do. Therefore, the microcomputer 150 can determine only whether the input voltage is higher or lower than the threshold voltage, with the fixed voltage determined by the configuration of the internal logic circuit as the threshold voltage.
The oscillation stop instruction unit 154 uses a fixed voltage determined by the configuration of the microcomputer 150 as a detection threshold voltage, and compares the input abnormality detection voltage with the detection threshold voltage.

The detection level instruction unit 153 determines a ratio (hereinafter referred to as “detection level”) between the amplitude detected by the abnormality detection circuit 170 and the abnormality detection voltage generated by the abnormality detection circuit 170, and based on the determined detection level. The abnormality detection circuit 170 is instructed to generate the abnormality detection voltage. For example, the detection level instruction unit 153 generates and outputs a detection level instruction signal representing the determined detection level.
As described above, when the impedance of the discharge lamp LA increases due to the end of the life of the discharge lamp LA or the like, the amplitude detected by the abnormality detection circuit 170 increases, so the abnormality detection voltage generated by the abnormality detection circuit 170 is increased. Becomes higher. Therefore, the detection level instruction unit 153 determines that the abnormality detection voltage generated by the abnormality detection circuit 170 is lower than the detection threshold voltage when the discharge lamp LA is normally lit, and the discharge lamp LA is abnormally lit. Determines the detection level so that the abnormality detection voltage generated by the abnormality detection circuit 170 is higher than the detection threshold voltage.

When the dimming control of the discharge lamp LA is not performed, the amplitude detected by the abnormality detection circuit 170 is constant when the discharge lamp LA is normally lit, but when the dimming control is performed on the discharge lamp LA, it is applied to the discharge lamp LA. Therefore, the amplitude detected by the abnormality detection circuit 170 changes. Therefore, it is necessary to change the detection level accordingly.
The detection level instruction unit 153 determines the detection level based on the dimming level determined by the dimming determination unit 151.

The abnormality detection circuit 170 includes a charging current generation circuit 171, a power storage circuit 172, and a discharge circuit 173.
The charging current generation circuit 171 detects the amplitude of the potential at the detection point, and generates a current proportional to the detected amplitude (hereinafter referred to as “charging current”).
The discharge circuit 173 is a variable resistance circuit that receives the detection level instruction signal output from the detection level instruction unit 153 and changes the resistance value based on the input detection level instruction signal.
The power storage circuit 172 is, for example, a capacitor and is charged with the charging current generated by the charging current generation circuit 171. The power storage circuit 172 is electrically connected in parallel with the discharge circuit 173 and is discharged by a current flowing through the discharge circuit 173 (hereinafter referred to as “discharge current”).
The abnormality detection circuit 170 outputs the voltage charged in the power storage circuit 172 as an abnormality detection voltage. The voltage charged in the storage circuit 172 is balanced at a voltage at which the charging current and the discharging current are equal. The discharge current is proportional to the voltage charged in the storage circuit 172. Therefore, the abnormality detection voltage is proportional to the amplitude detected by the charging current generation circuit 171. Further, the discharge current is inversely proportional to the resistance value of the discharge circuit 173. Therefore, the detection level changes based on the detection level instruction signal output from the detection level instruction unit 153.

FIG. 4 is an electric circuit diagram showing a specific circuit configuration of the abnormality detection circuit 170 in this embodiment.
In this example, it is assumed that the dimming determination unit 151 determines a dimming level selected from two dimming levels as the dimming level. For example, the dimming determination unit 151 selects a dimming level for lighting the discharge lamp LA from two dimming levels of 100% lighting and 70% dimming lighting.

The charging current generation circuit 171 includes a resistor R81, a resistor R82, a capacitor C83, a diode D84, and a diode D85.
The resistor R81 has one terminal electrically connected to the detection point of the load circuit 140.
The resistor R82 has one terminal electrically connected to the other terminal of the resistor R81, and the other terminal electrically connected to the ground wiring GND.
The capacitor C83 has one terminal electrically connected to the connection point between the resistor R81 and the resistor R82.
The diode D84 has an anode terminal electrically connected to the other terminal of the capacitor C83.
The diode D85 has a cathode terminal electrically connected to a connection point between the capacitor C83 and the diode D84, and an anode terminal electrically connected to the ground wiring GND.

  The voltage at the detection point of the load circuit 140 is divided by the resistors R81 and R82, and the DC component is cut by the capacitor C83. Of the current flowing through the capacitor C83, the current flowing in the direction of the arrow shown in the figure flows through the diode D84 to become a charging current, and the current flowing in the direction opposite to the arrow flows through the diode D85 through the ground wiring GND. Supplied from Thereby, the charging current generation circuit 171 generates a charging current that is proportional to the amplitude of the AC component of the potential at the detection point of the load circuit 140.

The power storage circuit 172 includes a capacitor C91.
The capacitor C91 has one terminal electrically connected to the cathode terminal of the diode D84, and the other terminal electrically connected to the ground wiring GND.
Thereby, the power storage circuit 172 is charged with the charging current generated by the charging current generation circuit 171.

The discharge circuit 173 is a circuit in which a resistor circuit 174 and a resistor circuit 175 are electrically connected in parallel.
The resistance circuit 174 has a resistance R01. The resistor R01 is a fixed resistor, and one terminal is electrically connected to a connection point between the diode D84 and the capacitor C91, and the other terminal is electrically connected to the ground wiring GND.

The resistor circuit 175 includes a resistor R02 and a switching circuit 178.
The resistor R02 is a fixed resistor, and one terminal is electrically connected to a connection point between the diode D84 and the capacitor C91.
The switching circuit 178 is a three-terminal (input terminal, reference terminal, output terminal) circuit, and the potential difference between the input terminal and the reference terminal is higher than a predetermined voltage (hereinafter referred to as “discharge threshold voltage”). In addition, when the output terminal and the reference terminal are electrically connected and the potential difference between the input terminal and the reference terminal is lower than the discharge threshold voltage, the output terminal and the reference terminal are insulated. The switching circuit 178 has an input terminal electrically connected to the output of the detection level instruction unit 153, an output terminal electrically connected to the other terminal of the resistor R02, and a reference terminal electrically connected to the ground wiring GND. Thereby, the switching circuit 178 becomes conductive when the potential of the detection level instruction signal output from the detection level instruction unit 153 is higher than the discharge threshold voltage.

The switching circuit 178 includes, for example, a resistor R03 and a transistor Q08. The resistor R03 is a fixed resistor, and one terminal is connected to the input terminal of the switching circuit 178. The transistor Q08 is an NPN bipolar transistor having a base terminal connected to the other terminal of the resistor R03, a collector terminal connected to the output terminal of the switching circuit 178, and an emitter terminal connected to the reference terminal of the switching circuit 178. is doing.
The configuration of the switching circuit 178 is not limited to this, and may be, for example, a configuration using an FET, a configuration using a relay, or a configuration using a photocoupler.

When the potential of the detection level instruction signal output from the detection level instruction unit 153 is lower than the discharge threshold voltage, the switching circuit 178 is insulated, so that the (equivalent) resistance value of the discharge circuit 173 is equal to the resistance value of the resistor R01. .
In addition, when the potential of the detection level instruction signal output from the detection level instruction unit 153 is higher than the discharge threshold voltage, the switching circuit 178 becomes conductive, so that the resistance value of the discharge circuit 173 is a parallel circuit of the resistor R01 and the resistor R02. Is equal to the resistance value.
That is, the discharge circuit 173 can take two resistance values, and based on the detection level instruction signal output from the detection level instruction unit 153, a circuit that takes one of the two resistance values. It is.

  Next, the operation will be described.

  FIG. 5 is a flowchart showing a dimming process flow in which the discharge lamp lighting device 100 according to this embodiment adjusts the dimming level of the discharge lamp LA.

In the dimming level determination step S511, the dimming determination unit 151 determines the dimming level.
In the frequency determination step S512, the frequency instruction unit 152 determines the frequency (lighting frequency) of the high-frequency AC voltage generated by the inverter circuit 130 based on the dimming level determined by the dimming determination unit 151 in the dimming level determination step S511. decide.
In the frequency instruction step S513, the frequency instruction unit 152 instructs the inverter control circuit 133 to generate a high-frequency AC voltage having the frequency determined in the frequency determination step S512.
In the AC voltage generation step S514, the inverter control circuit 133 generates a drive signal having the frequency instructed from the frequency instruction unit 152 in the frequency instruction step S513. As a result, the inverter circuit 130 generates a high-frequency AC voltage having the instructed frequency.
In the detection level determination step S515, the detection level instruction unit 153 determines the detection level based on the dimming level determined by the dimming determination unit 151 in the dimming level determination step S511.
In the detection level instruction step S516, the detection level instruction unit 153 instructs the abnormality detection circuit 170 to generate an abnormality detection voltage at the detection level determined in the detection level determination step S515.
In the abnormality detection voltage generation step S517, the abnormality detection circuit 170 generates an abnormality detection voltage at the detection level instructed from the detection level instruction unit 153 in the detection level instruction step S516.

FIG. 6 is a sequence diagram showing the operation of the discharge lamp lighting device 100 in this embodiment.
In this example, at time t ₀ , the dimming determination unit 151 determines to light 100% of the discharge lamp LA, and at time t ₁ , the dimming determination unit 151 determines to light 70% of the discharge lamp LA. Then, it is assumed that at time t ₂ , the dimming determination unit 151 determines to turn on the discharge lamp LA 100% again. Further, at time t _3, the abnormality occurs in the discharge lamp LA, the discharge lamp LA is assumed to abnormally turned on.

The frequency instruction unit 152 determines the lighting frequency 612 based on the dimming level 611 determined by the dimming determination unit 151. The inverter circuit 130 generates a high-frequency AC voltage based on the lighting frequency 612 determined by the frequency instruction unit 152 and applies it to the load circuit 140.
The abnormality detection circuit 170 detects the amplitude 614 based on the potential 613 at the detection point, and generates an abnormality detection voltage 616.

At time t _1, the lower the frequency of the high-frequency AC voltage inverter circuit 130 is generated, the amplitude 614 of detecting the charging current generating circuit 171 increases. On the other hand, since the detection level instruction signal 615 output from the detection level instruction unit 153 becomes a high potential and the resistance value of the discharge circuit 173 decreases, the abnormality detection voltage 616 generated by the abnormality detection circuit 170 does not change, and the detection threshold value It remains below voltage 617. Therefore, the oscillation stop instruction unit 154 does not recognize that the discharge lamp LA is abnormal.

In time t _2, the frequency of the high-frequency AC voltage inverter circuit 130 to generate increases, the amplitude 614 of detecting the charging current generation circuit 171 is reduced. On the other hand, since the detection level instruction signal 615 output from the detection level instruction unit 153 becomes a low potential and the resistance value of the discharge circuit 173 increases, the abnormality detection voltage 616 generated by the abnormality detection circuit 170 does not change.

At time _{t 3,} the abnormality occurs in the discharge lamp LA, the amplitude 614 of detecting the charging current generating circuit 171 increases. Since the detection level instruction signal 615 output from the detection level instruction unit 153 does not change, the resistance value of the discharge circuit 173 does not change, and the abnormality detection voltage 616 generated by the abnormality detection circuit 170 becomes higher and higher than the detection threshold voltage 617. Become. As a result, the oscillation stop instruction unit 154 detects an abnormality in the discharge lamp LA and outputs an oscillation stop signal 618. The inverter circuit 130 stops the generation of the high-frequency AC voltage based on the oscillation stop signal 618 output from the oscillation stop instruction unit 154.

As described above, when the voltage applied to the discharge lamp LA for dimming is increased, the detection level instruction unit 153 decreases the detection level. Therefore, if the discharge lamp LA is normally lit, the abnormality detection circuit 170 is detected. The abnormality detection voltage generated by is lower than the detection threshold voltage. Therefore, the oscillation stop instruction unit 154 does not erroneously determine that the discharge lamp LA is abnormally lit.
Further, when the voltage applied to the discharge lamp LA is lowered for dimming, the detection level instruction unit 153 increases the detection level. Therefore, if the discharge lamp LA is normally lit, the abnormality detection circuit 170 is always provided. The abnormality detection voltage generated by is a voltage slightly lower than the detection threshold voltage. Therefore, if the discharge lamp LA is abnormally lit and the abnormality detection voltage generated by the abnormality detection circuit 170 is increased even a little, it becomes higher than the detection threshold voltage, and immediately, the oscillation stop instruction unit 154 detects the abnormality, The oscillation of the inverter circuit 130 is stopped.
Thereby, abnormal lighting of the discharge lamp LA can be detected with high accuracy.

  Further, since the level of the abnormality detection voltage generated by the abnormality detection circuit 170 is adjusted according to the detection level determined by the detection level instruction unit 153, even if the microcomputer 150 that does not incorporate the analog-digital converter is used, It can be determined whether or not the detection voltage is higher than the detection threshold voltage. Of course, it is not necessary to provide an analog-digital converter, a comparator, or the like in addition to the microcomputer 150. Thereby, the manufacturing cost of the discharge lamp lighting device 100 can be reduced.

Embodiment 2. FIG.
The second embodiment will be described with reference to FIGS.
Since the appearance of the lighting fixture 800 and the circuit configuration of the discharge lamp lighting device 100 in this embodiment are the same as those described in Embodiment 1, description thereof is omitted here.

In the first embodiment, the frequency instruction unit 152 changes the frequency of the high-frequency AC voltage generated by the inverter circuit 130 as soon as the frequency is instructed, and the voltage applied to the discharge lamp LA changes. There may be a delay after the frequency instruction unit 152 indicates the frequency until the voltage actually applied to the discharge lamp LA changes.
In this embodiment, a case where such a delay occurs will be described.

  FIG. 7 is a flowchart showing a flow of an abnormality detection process in which the discharge lamp lighting device 100 in this embodiment detects abnormal lighting of the discharge lamp LA.

In the detection level determination step S521, the oscillation stop instruction unit 154 determines whether or not the detection level determined by the detection level instruction unit 153 has increased. Here, “the detection level is increased” means that the abnormality detection circuit 170 generates the abnormality detection when the detection level determined by the detection level instruction unit 153 changes and the amplitude detected by the abnormality detection circuit 170 is the same. The case where the voltage becomes high. If it is determined that the detection level has increased, the process proceeds to a mask time elapse waiting step S522. When it is determined that the detection level has decreased (or has not changed), the process proceeds to the abnormality determination step S523.
In the mask time elapse waiting step S522, the oscillation stop instructing unit 154 measures an elapse time after the detection level instructing unit 153 instructs the abnormality detecting circuit 170 to detect a detection level, and determines a predetermined time (hereinafter, “mask time” It is determined whether or not “.” Has elapsed. If it is determined that the mask time has not elapsed, the mask time elapse waiting step S522 is repeated. When it is determined that the mask time has elapsed, the process proceeds to the abnormality determination step S523.
In the abnormality determination step S523, the oscillation stop instruction unit 154 determines which is higher by comparing the abnormality detection voltage generated by the abnormality detection circuit 170 with the detection threshold voltage. When it is determined that the abnormality detection voltage is higher than the detection threshold voltage, the process proceeds to the oscillation stop instruction step S524. When it is determined that the abnormality detection voltage is lower than the detection threshold voltage, the process returns to the detection level determination step S521.
In the oscillation stop instruction step S524, the oscillation stop instruction unit 154 instructs the inverter control circuit 133 to stop generating the high-frequency AC voltage.
In the oscillation stop step S525, the inverter control circuit 133 generates a drive signal based on an instruction from the oscillation stop instruction unit 154, and the inverter circuit 130 stops generating the high-frequency AC voltage.

FIG. 8 is a sequence diagram showing the operation of the discharge lamp lighting device 100 in this embodiment.
Similar to FIG. 6 described in the first embodiment, at time t ₀ , the dimming determination unit 151 determines that 100% of the discharge lamp LA is lit, and at the time t ₁ , the dimming determination unit 151 performs the discharge lamp LA. the decision to light up 70%, the time t _2, the dimming decision unit 151 is assumed to have decided to light the discharge lamp LA again 100%. Further, at time t _3, the abnormality occurs in the discharge lamp LA, the discharge lamp LA is assumed to abnormally turned on.

The amplitude 614 detected by the charging current generation circuit 171 changes at time t ₁ because there is a delay from when the frequency instruction unit 152 indicates the frequency until the voltage actually applied to the discharge lamp LA changes. Without change, the delay time 621 changes. Similarly, in time t _2, the amplitude 614 does not change, changes after the delay time 622 has elapsed.

In the delay time 621, the amplitude 614 detected by the charging current generation circuit 171 has not yet increased, but since the detection level instruction unit 153 outputs the detection level instruction signal 615 having a high potential, the resistance of the discharge circuit 173 The value is getting smaller. For this reason, the abnormality detection voltage 616 generated by the abnormality detection circuit 170 temporarily decreases.
After the delay time 621 has elapsed, the amplitude 614 detected by the charging current generation circuit 171 increases, and the abnormality detection voltage generated by the abnormality detection circuit 170 returns to the correct value.
Therefore, if the discharge lamp LA starts to light abnormally during the delay time 621, the oscillation stop instructing unit 154 detects the abnormality of the discharge lamp LA after the delay time 621 has elapsed.
In general, since the delay time 621 is short, even if the abnormality of the discharge lamp LA cannot be detected during the delay time 621, there is no problem.

In the delay time 622, the amplitude 614 detected by the charging current generation circuit 171 has not yet decreased, but since the detection level instruction unit 153 outputs the detection level instruction signal 615 having a low potential, the resistance of the discharge circuit 173 The value is increasing. For this reason, the abnormality detection voltage 616 generated by the abnormality detection circuit 170 temporarily increases.
After the delay time 622 has elapsed, the amplitude 614 detected by the charging current generation circuit 171 decreases, and the abnormality detection voltage generated by the abnormality detection circuit 170 returns to the correct value.
Therefore, the abnormality detection voltage generated by the abnormality detection circuit 170 may be higher than the detection threshold voltage during the delay time 622 and for a short time thereafter.

Therefore, the oscillation stop instructing unit 154 in this embodiment sets the time 623 longer than the delay time 622 as the mask time, and does not determine abnormality during the mask time 623.
Thereby, when the detection level is lowered, the oscillation stop instructing unit 154 erroneously determines that the discharge lamp LA is abnormally lit due to a delay in actually decreasing the voltage applied to the discharge lamp LA. Can be prevented.
If the discharge lamp LA starts to light abnormally during the delay time, the oscillation stop instruction unit 154 detects the abnormality of the discharge lamp LA after the mask time 623 has elapsed.
Since the delay time 622 is generally short, if the mask time 623 is set to an appropriate length, there is no problem even if the abnormality of the discharge lamp LA cannot be detected during the mask time 623.

  As described above, when the detection level is increased, the oscillation stop instruction unit 154 does not make an abnormality determination until the mask time 623 elapses. Therefore, if the oscillation stop instruction unit 154 erroneously lights the discharge lamp LA abnormally. Without determination, abnormal lighting of the discharge lamp LA can be accurately detected.

Embodiment 3 FIG.
The third embodiment will be described with reference to FIGS.
Since the appearance of the lighting fixture 800 and the circuit configuration of the discharge lamp lighting device 100 in this embodiment are the same as those described in Embodiment 1, description thereof is omitted here.

  In this embodiment, as in the second embodiment, another countermeasure against a case where a delay occurs until the voltage actually applied to the discharge lamp LA changes after the frequency instruction unit 152 indicates the frequency will be described. To do.

FIG. 9 is a flowchart showing a dimming process flow in which the discharge lamp lighting device 100 according to this embodiment adjusts the dimming level of the discharge lamp LA.
Note that portions common to the dimming processing described in Embodiment 1 are denoted by the same reference numerals, and description thereof is omitted here.

After detection level determination step S515, in detection level determination step S531, detection level instruction unit 153 determines whether or not the detection level determined by detection level instruction unit 153 has increased. When it is determined that the detection level has increased, the process proceeds to a mask time elapse waiting step S532. If it is determined that the detection level has decreased (or has not changed), the process proceeds to a detection level instruction step S516.
In the mask time elapse waiting step S532, the detection level instruction unit 153 measures the elapsed time after the frequency instruction unit 152 instructs the inverter control circuit 133 to specify the frequency, and determines whether the mask time has elapsed. To do. If it is determined that the mask time has not elapsed, the mask time elapse waiting step S532 is repeated. If it is determined that the mask time has elapsed, the process proceeds to the detection level instruction step S516.

FIG. 10 is a sequence diagram showing the operation of the discharge lamp lighting device 100 in this embodiment.
As in FIG. 8 described in the second embodiment, at time t ₀ , the dimming determination unit 151 determines that 100% of the discharge lamp LA is lit, and at the time t ₁ , the dimming determination unit 151 is at the discharge lamp LA. the decision to light up 70%, the time t _2, the dimming decision unit 151 is assumed to have decided to light the discharge lamp LA again 100%. Further, at time t _3, the abnormality occurs in the discharge lamp LA, the discharge lamp LA is assumed to abnormally turned on.
The mask time 624 is longer than the delay time 622.

In the delay time 622, the amplitude 614 detected by the charging current generation circuit 171 has not yet decreased, but the detection level instruction signal 615 output by the detection level instruction unit 153 remains at a high potential, so the resistance value of the discharge circuit 173 The abnormality detection voltage 616 generated by the abnormality detection circuit 170 does not change.
The amplitude 614 detected by the charging current generation circuit 171 becomes small during the period after the delay time 622 has elapsed and before the mask time 624 has elapsed, but the detection level instruction signal 615 output by the detection level instruction unit 153 has a high potential. Therefore, the resistance value of the discharge circuit 173 does not change, and the abnormality detection voltage 616 generated by the abnormality detection circuit 170 becomes small.
After the mask time 624 elapses, the detection level instruction unit 153 outputs the detection level instruction signal 615 having a low potential. Therefore, the resistance value of the discharge circuit 173 increases, and the abnormality detection voltage 616 generated by the abnormality detection circuit 170 is Return to the correct value.

  Thus, when increasing the detection level, during the mask time 624 longer than the delay time 622, the detection level change is not instructed, and after the mask time 624 has elapsed, the detection level change is instructed. If the discharge lamp LA is normally lit, the abnormality detection voltage 616 does not become higher than the detection threshold voltage. Therefore, the oscillation stop instructing unit 154 does not erroneously determine that the discharge lamp LA is abnormally lit, and it is possible to accurately detect abnormal lighting of the discharge lamp LA.

Embodiment 4 FIG.
The fourth embodiment will be described with reference to FIG.
Since the appearance of the lighting fixture 800 and the circuit configuration of the discharge lamp lighting device 100 in this embodiment are the same as those described in Embodiment 1, description thereof is omitted here.

  In this embodiment, a case where the dimming level is higher than the two levels will be described.

FIG. 11 is an electric circuit diagram showing a specific circuit configuration of the abnormality detection circuit 170 in this embodiment.
Note that portions common to the abnormality detection circuit 170 described in Embodiment 1 are denoted by the same reference numerals, and description thereof is omitted here.

  In this example, it is assumed that the dimming determination unit 151 determines a dimming level selected from three or four dimming levels as the dimming level. For example, the dimming determination unit 151 selects the dimming level from three dimming levels of 100% lighting, 80% dimming lighting, and 60% dimming lighting.

  The detection level instruction unit 153 generates and outputs two detection level instruction signals 615a and 615b. For example, when a detection level corresponding to 100% lighting is instructed, the detection level instruction unit 153 sets the two detection level instruction signals 615a and 615b to low potentials. When the detection level corresponding to 80% dimming lighting is instructed, the detection level instruction unit 153 sets the detection level instruction signal 615a to a low potential and the detection level instruction signal 615b to a high potential. When instructing a detection level corresponding to 60% dimming lighting, the detection level instruction unit 153 sets the detection level instruction signal 615a to a high potential and the detection level instruction signal 615b to a low potential.

The discharge circuit 173 further includes a resistor circuit 176, and the resistor circuit 174, the resistor circuit 175, and the resistor circuit 176 are connected in parallel.
The switching circuit 178 of the resistance circuit 175 conducts when the detection level instruction signal 615b of the two detection level instruction signals output from the detection level instruction unit 153 is high potential, and insulates when the detection level instruction signal 615b is low potential.
The resistance circuit 176 has a configuration similar to that of the resistance circuit 175, and includes a resistance R04 and a switching circuit 179. The resistor R04 is a fixed resistor. For example, the switching circuit 179 includes a resistor R05 and a transistor Q09. The switching circuit 179 conducts when the detection level instruction signal 615a of the two detection level instruction signals output from the detection level instruction unit 153 is high potential, and insulates when the detection level instruction signal 615a is low potential.

When the detection level instruction unit 153 instructs a detection level corresponding to 100% lighting, both the switching circuit 178 and the switching circuit 179 are turned off, so that the resistance value of the discharge circuit 173 becomes equal to the resistance value of the resistor R01. .
When the detection level instruction unit 153 instructs a detection level corresponding to 80% dimming lighting, the switching circuit 178 is turned on and the switching circuit 179 is turned off, so that the resistance value of the discharge circuit 173 is the resistance R01 and the resistance R02. It becomes equal to the resistance value of the parallel circuit.
When the detection level instruction unit 153 instructs a detection level corresponding to 60% dimming lighting, the switching circuit 178 is turned off and the switching circuit 179 is turned on. Therefore, the resistance value of the discharge circuit 173 is the resistance R01 and the resistance R03. It becomes equal to the resistance value of the parallel circuit.
That is, the discharge circuit 173 can take three resistance values, and takes one of the three resistance values based on the detection level instruction signal output from the detection level instruction unit 153.
If the detection level instruction signals 615a and 615b are both set to a high potential, the resistance value of the discharge circuit 173 becomes equal to the resistance value of the parallel circuit of the resistor R01, the resistor R02, and the resistor R03. It is also possible to take two resistance values.

  Thus, by increasing the number of resistance circuits that form the discharge circuit 173, the resistance value that the discharge circuit 173 can take can be increased. If the number of resistance circuits is n, the discharge circuit 173 theoretically can take 2 (n-1) power resistance values.

  Therefore, even when the dimming level is not two, but more, the resistance value of the discharge circuit 173 can be set to an appropriate value, and abnormal lighting of the discharge lamp LA can be accurately detected. .

Embodiment 5 FIG.
A fifth embodiment will be described with reference to FIG.
Since the appearance of the lighting fixture 800 and the circuit configuration of the discharge lamp lighting device 100 in this embodiment are the same as those described in Embodiment 1, description thereof is omitted here.

  In the fourth embodiment, the configuration in which the number of resistance circuits configuring the discharge circuit 173 is increased when the dimming level is high is described. However, in this embodiment, the number of resistance circuits configuring the discharge circuit 173 is increased. First, a case where the light control level is high or a case where continuous light control (stepless light control) is performed will be described.

The detection level instruction unit 153 generates and outputs a detection level instruction signal subjected to pulse width modulation (PWM) based on the dimming level determined by the dimming determination unit 151.
The detection level instruction signal generated by the detection level instruction unit 153 is a signal that repeats a high potential and a low potential in a predetermined cycle (for example, 1 millisecond) sufficiently longer than the cycle of the high-frequency AC voltage generated by the inverter circuit 130. is there. A duty ratio between a period during which the detection level instruction signal is high potential (hereinafter referred to as “on time”) and a period during which the detection level instruction signal is low potential (hereinafter referred to as “off time”) instructs the abnormality detection circuit 170. Indicates the detection level.
For example, when the on-duty is 0% (that is, the detection level instruction signal is constant at a low potential), the detection level corresponds to 100% lighting, and when the on-duty is 25%, the detection level corresponds to 80% dimming lighting. When the on-duty is 50%, the detection level corresponding to 60% dimming lighting is shown, and when the on-duty is 75%, the detection level corresponding to 40% dimming lighting is shown. Since the on-duty can be continuously changed, it is possible to cope with stepless dimming.
The detection level instruction unit 153 determines an on time and an off time based on the dimming level determined by the dimming determination unit 151, and outputs a high potential detection level instruction signal during the determined on time, During the determined off time, the output of the low potential detection level instruction signal is repeated.

FIG. 12 is a sequence diagram showing the operation of the discharge lamp lighting device 100 in this embodiment.
In this example, at time t ₀ , the dimming determination unit 151 determines to light 100% of the discharge lamp LA, and at time t ₁ , the dimming determination unit 151 performs 80% light control of the discharge lamp LA. At time t ₂ , the dimming determination unit 151 determines that the discharge lamp LA is to be dimmed 60%, and at time t ₃ , the dimming determination unit 151 is 40% dimmed to light the discharge lamp LA. Suppose you decide to do.

The frequency instruction unit 152 determines the frequency based on the dimming level determined by the dimming determination unit 151 and instructs the inverter circuit 130. The inverter circuit 130 generates a high-frequency AC voltage having the instructed frequency and applies it to the load circuit 140. Thereby, the brightness of the discharge lamp LA changes.
The amplitude 614 detected by the charging current generation circuit 171 changes as the high-frequency AC voltage generated by the inverter circuit 130 changes.

The detection level instruction unit 153 outputs a detection level instruction signal subjected to pulse width modulation.
The discharge circuit 173 takes a resistance value selected from two resistance values based on the detection level instruction signal output from the detection level instruction unit 153. When the detection level instruction signal has a high potential, the resistance value of the discharge circuit 173 is equal to the resistance value (first resistance value) of the parallel circuit of the resistors R01 and R02, and the detection level instruction signal has a low potential. The resistance value of the discharge circuit 173 is equal to the resistance value (second resistance value) of the resistor R01.
Therefore, the discharge circuit 173 takes the first resistance value during the on-time 631 and takes the second resistance value during the off-time 632 based on an instruction from the detection level instruction unit 153.

Since the first resistance value is smaller than the second resistance value, the discharge current flowing through the discharge circuit 173 increases during the on-time 631, and the abnormality detection voltage 616 generated by the abnormality detection circuit 170 tends to decrease. . During the off time 632, the discharge current flowing through the discharge circuit 173 decreases, and the abnormality detection voltage 616 generated by the abnormality detection circuit 170 tends to increase.
When the on-time 631 and the off-time 632 are alternately repeated, the amount of change in which the abnormality detection voltage 616 decreases during the on-time 631 is exactly equal to the amount of change in which the abnormality detection voltage 616 increases during the off-time 632. The abnormality detection voltage 616 is stabilized.
Therefore, the abnormality detection voltage 616 becomes lower as the ON time 631 is longer, and the abnormality detection voltage 616 is higher as the OFF time 632 is longer.

  For example, the detection level instruction unit 153 detects the abnormality detection voltage 616 generated by the abnormality detection circuit 170 corresponding to the amplitude 614 detected by the charging current generation circuit 171 when the discharge lamp LA is normally lit. A preset on time and off time are stored so as to be slightly lower than the threshold voltage 617. The detection level instruction unit 153 selects the on time and the off time based on the dimming level determined by the dimming determination unit 151 from the stored on time and off time.

As described above, the detection level instruction unit 153 outputs a pulse-modulated detection level instruction signal to increase the number of dimming levels or perform continuous dimming (stepless dimming). However, without complicating the configuration of the discharge circuit 173, the resistance value (average value) of the discharge circuit 173 can be set to an appropriate value, and abnormal lighting of the discharge lamp LA can be detected with high accuracy. .
Thereby, since it is not necessary to increase the components of the discharge circuit 173, the manufacturing cost of the discharge lamp lighting device 100 can be suppressed.

FIG. 3 is a perspective view illustrating an appearance of a lighting fixture 800 according to Embodiment 1. FIG. 2 is an electric circuit diagram illustrating a circuit configuration of the discharge lamp lighting device 100 according to the first embodiment. FIG. 3 is a detailed block diagram illustrating the configuration of internal blocks of the microcomputer 150 and the abnormality detection circuit 170 in the first embodiment. FIG. 3 is an electric circuit diagram illustrating a specific circuit configuration of the abnormality detection circuit 170 in the first embodiment. The flowchart figure which shows the flow of the light control process which the discharge lamp lighting device 100 in Embodiment 1 adjusts the light control level of the discharge lamp LA. FIG. 3 is a sequence diagram showing an operation of the discharge lamp lighting device 100 in the first embodiment. The flowchart figure which shows the flow of the abnormality detection process which the discharge lamp lighting device 100 in Embodiment 2 detects abnormal lighting of the discharge lamp LA. FIG. 9 is a sequence diagram showing an operation of the discharge lamp lighting device 100 according to the second embodiment. The flowchart figure which shows the flow of the light control process which the discharge lamp lighting device 100 in Embodiment 3 adjusts the light control level of the discharge lamp LA. FIG. 10 is a sequence diagram showing the operation of the discharge lamp lighting device 100 according to the third embodiment. FIG. 6 is an electric circuit diagram showing a specific circuit configuration of an abnormality detection circuit 170 in the fourth embodiment. FIG. 10 is a sequence diagram showing an operation of the discharge lamp lighting device 100 according to the fifth embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 Discharge lamp lighting device, 110 Power supply rectifier circuit, 120 Active filter circuit, 122 PFC, 130 Inverter circuit, 133 Inverter control circuit, 140 Load circuit, 143 Discharge lamp circuit, 145 Discharge lamp connection part, 150 Microcomputer, 151 Dimming Determination unit, 152 frequency instruction unit, 153 detection level instruction unit, 154 oscillation stop instruction unit, 160 operation input circuit, 170 abnormality detection circuit, 171 charge current generation circuit, 172 power storage circuit, 173 discharge circuit, 174-176 resistance circuit, 178, 179 switching circuit, 800 lighting fixture, 810 discharge lamp socket, AC AC power supply, C25, C83, C91 capacitor, C42 coupling capacitor, C44 starting capacitor, D24, D84, D85 diode, DB diode Bridge, GND ground wiring, L21, L41 choke coil, LA discharge lamp, Q23, Q31, Q32 FET, Q08, Q09 transistor, R81, R82, R01 to R05 resistors.

Claims (5)

A load circuit in which a choke coil, a coupling capacitor, and a discharge lamp circuit are electrically connected in series;
An inverter circuit for generating an alternating voltage to be applied to the load circuit;
Based on the potential at one end of the discharge lamp circuit, an abnormality detection circuit that detects the amplitude of the potential at one end of the discharge lamp circuit and generates an abnormality detection voltage proportional to the detected amplitude;
A microcomputer for controlling the inverter circuit,
The discharge lamp circuit has a discharge lamp connecting portion that can be electrically connected to the discharge lamp, and a starting capacitor that is electrically connected in parallel with the discharge lamp when the discharge lamp is electrically connected to the discharge lamp connecting portion.
The microcomputer is
A dimming determination unit for determining the brightness for lighting the discharge lamp electrically connected to the discharge lamp connection unit;
The frequency of the AC voltage generated by the inverter circuit is determined based on the brightness determined by the dimming determination unit, and the inverter circuit is instructed to generate the AC voltage based on the determined frequency. A frequency indicator;
Based on the brightness determined by the dimming determination unit, a ratio between the amplitude detected by the abnormality detection circuit and the abnormality detection voltage generated by the abnormality detection circuit is determined, and the abnormality detection voltage is determined based on the determined ratio. A detection level instruction unit for instructing the abnormality detection circuit to generate
Based on the abnormality detection voltage generated by the abnormality detection circuit, an oscillation stop instruction that instructs the inverter circuit to stop generating the AC voltage when the abnormality detection voltage is higher than a predetermined detection threshold voltage And a discharge lamp lighting device. The detection level instruction unit outputs a detection level instruction signal representing the determined ratio,
The abnormality detection circuit
A charging current generating circuit that detects an amplitude of a potential at one end of the discharge lamp connecting portion and generates a charging current proportional to the detected amplitude;
Based on the detection level instruction signal output from the detection level instruction unit, a discharge circuit composed of a variable resistance circuit whose resistance value changes;
2. The storage circuit according to claim 1, further comprising: a storage circuit that is charged by a charging current generated by the charging current generation circuit, is discharged by a current flowing through the discharge circuit, and uses the charged voltage as the abnormality detection voltage. Discharge lamp lighting device. The discharge circuit is a circuit in which at least two resistance circuits are electrically connected in parallel,
The first resistor circuit among the resistor circuits is a fixed resistor,
The second resistor circuit among the resistor circuits is a circuit in which a fixed resistor and a switching circuit are electrically connected in series,
3. The discharge lamp lighting device according to claim 2, wherein the switching circuit is turned on when the potential of the detection level instruction signal output from the detection level instruction section is higher than a predetermined discharge threshold voltage. The discharge circuit can take two resistance values, and based on the detection level instruction signal output by the detection level instruction section, takes one of the two resistance values,
The detection level instruction unit determines an on time and an off time based on the brightness determined by the dimming determination unit, and as the detection level instruction signal, during the on time, of the two resistance values. Instructing the discharge circuit to take a first resistance value, and instructing the discharge circuit to take a second resistance value of the two resistance values during the off-time. The discharge lamp lighting device according to claim 2 or 3, wherein a repeating signal is output. The discharge lamp lighting device according to any one of claims 1 to 4,
A lighting fixture comprising: a discharge lamp socket to which the discharge lamp can be detachably attached, and which electrically connects the attached discharge lamp to the discharge lamp connecting portion.

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