JP2012089451A - Lighting device of discharge lamp and lighting fixture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device of a discharge lamp in which the end-of-life state of the discharge lamp can be detected reliably, and melting of a socket can be prevented.SOLUTION: The lighting device of a discharge lamp comprises a DC power supply 1 and an inverter 21 which supply a DC voltage to the discharge lamp La while inverting into a high frequency voltage, and a detector 5 which detects the high frequency voltage output from the inverter 21. The detector 5 converts a detection voltage of a resistor R10 based on the high frequency voltage into a voltage having a value equal to or higher than the breakover voltage of a diac DA2 which is higher than a first threshold when the detection voltage exceeds the first threshold, and stops operation of the inverter 21 when the detection voltage is equal to or higher than the breakover voltage of the diac DA2.

Description

  The present invention relates to a discharge lamp lighting device and a lighting fixture. In particular, the present invention relates to a discharge lamp lighting device having a function of detecting the end of life of a discharge lamp and a lighting fixture equipped with the discharge lamp lighting device.

  2. Description of the Related Art Conventionally, a discharge lamp lighting circuit that has an inverter circuit and a resonance circuit connected to the output side of the inverter circuit and controls the lighting of the discharge lamp with the output of the resonance circuit has been proposed. In general, a fluorescent lamp is used as the discharge lamp. In the case of a fluorescent lamp, at the end of the lifetime, the filament becomes in an end-of-life state (so-called Emires state) in which the electron-emitting substance (referred to as an emitter) is consumed. As a result of the phenomenon that the tube voltage of the discharge lamp rises due to the Emires state, excessive stress is generated in the discharge lamp lighting device. Therefore, it is desired to detect such an Emiless state to protect the discharge lamp lighting circuit and to further improve the reliability of the discharge lamp lighting circuit.

  As a discharge lamp lighting device capable of detecting such an abnormal state such as an Emires state, the following Patent Documents 1 to 4 are known.

  The discharge lamp lighting device described in Patent Document 1 has two abnormality detection circuits that operate according to a dimming state set by a dimmer operated from the outside. By switching the abnormality detection circuit, the abnormal state including the end of the life of the discharge lamp is reliably detected without malfunction, and the destruction of the constituent elements is prevented.

  The discharge lamp lighting device described in Patent Document 2 prevents malfunction of the abnormality detection circuit by changing the detection sensitivity in the abnormality detection circuit according to the dimming state set by the dimmer operated from the outside. Is.

  The discharge lamp lighting device described in Patent Document 3 prevents the abnormality detection circuit from malfunctioning due to the characteristics of the components constituting the abnormality detection circuit when the ambient temperature of the discharge lamp is low or high, and the tube voltage decreases. In this case, the abnormality detection circuit operates normally.

  The discharge lamp lighting device described in Patent Document 4 changes the detection voltage in the abnormality detection circuit according to the type of the discharge lamp determined by the discharge lamp determination circuit, and makes the detection voltage substantially constant, This is to reliably detect the end of life of multiple types of discharge lamps.

JP-A-11-135288 Japanese Patent Laid-Open No. 11-204286 Japanese Patent Laid-Open No. 2003-007487 Japanese Patent Application Laid-Open No. 2003-066849

  Thus, some conventional discharge lamp lighting devices have a so-called Emiles detection circuit that stops the operation of an inverter circuit or the like when the tube voltage exceeds a predetermined value. In some cases, the detection threshold for detecting an abnormality is changed in accordance with the voltage of the discharge lamp to prevent malfunction of the Emires detection circuit and to reliably detect the abnormal state of the discharge lamp.

  However, when the luminaire is used continuously, the tube voltage of the discharge lamp is lower in the initial state of the Emires state between the initial state of use and the initial state of the Emires state. FIG. 6 is a diagram illustrating a change in tube voltage with the passage of time in the related art. Further, in a lighting fixture having a structure in which the discharge lamp is disposed near the reflector or the discharge lamp is covered with a panel or the like, the temperature difference between the initial use state and the initial Emires state becomes large. In this case, since it is necessary to set a detection threshold for detecting an abnormality in the Emires detection circuit to a higher value, the detection sensitivity of the Emires detection circuit is further deteriorated. Therefore, the power inserted into the filament of the discharge lamp increases until an abnormality is detected exceeding the predetermined tube voltage, and abnormal heat generation occurs at the tube end of the discharge lamp, so that a socket for holding the discharge lamp is provided. There was a problem that it melted. In other words, the Emires state was detected only when the Emires terminal state, which is the terminal state of the Emires state, was reached.

  On the other hand, when the detection threshold is set low in advance so that the detection sensitivity in the Emires detection circuit does not deteriorate, the tube voltage of the discharge lamp is higher in the initial use state than in the initial Emires state. Even though the discharge lamp was normal, an abnormality was sometimes detected. Therefore, the Emires state that should be recognized as abnormal may not be detected with accurate timing.

  Thus, when the detection threshold value for detecting an abnormality is set high, there is a possibility that the Emiless state (end-of-life state) of the discharge lamp can be detected, but the socket may be melted. there were. On the other hand, when the detection threshold is set low, the socket can be prevented from melting, but the Emires state of the discharge lamp cannot be detected.

  The present invention has been made in view of the above circumstances, and is capable of reliably detecting the end-of-life state of a discharge lamp and capable of preventing the socket from melting and a lighting fixture. The purpose is to provide.

  In order to solve the above-mentioned problems, a discharge lamp lighting device according to the present invention detects a high-frequency power supply unit that converts a DC voltage into a high-frequency voltage and supplies the high-frequency voltage to the discharge lamp, and detects the high-frequency voltage output from the high-frequency power supply unit A detection unit, and when the detection voltage based on the high-frequency voltage exceeds a first threshold, the detection unit converts the detection voltage to a value greater than or equal to a second threshold greater than the first threshold, When the detection voltage of the detection unit is equal to or higher than the second threshold value, the operation of the high frequency power supply unit is stopped.

  Further, in the present invention, an oscillation control unit for controlling the output of the high frequency power supply unit is provided, and the high frequency power supply unit includes two switching elements and a resonance circuit including a DC cut capacitor, and the oscillation A control part is comprised by the drive transformer for carrying out the self-excitation drive of the said switching element.

  Further, in the present invention, when the tube voltage of the discharge lamp rises by about 25% with respect to stable lighting, the resistance value of the resistance portion of the detection portion is set so that the detection voltage exceeds the first threshold value. Is done.

  In the present invention, when the power inserted into the filament of the discharge lamp reaches approximately 20 W, the resistance value of the resistance portion of the detection portion is set so that the detection voltage exceeds the first threshold value. The

  Moreover, the lighting fixture of this invention is equipped with one of the said discharge lamp lighting devices, and the fixture main body holding the said discharge lamp lighting device.

  According to the present invention, the end-of-life state of the discharge lamp can be reliably detected, and the socket can be prevented from melting.

The circuit diagram which shows an example of the electrical circuit structure of the discharge lamp lighting device in embodiment of this invention The figure which shows the example of an output of each part of the discharge lamp lighting device in embodiment of this invention in time series The figure which shows an example of the discharge lamp lighting device accommodated in the case in embodiment of this invention The figure which shows an example of the lighting fixture in embodiment of this invention The figure which shows an example of the lighting fixture which is easy to accumulate heat in embodiment of this invention The figure which shows the change of the tube voltage of the discharge lamp with time progress in the conventional discharge lamp lighting device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The discharge lamp lighting device of the present embodiment is for lighting a general hot cathode type discharge lamp La having a pair of filaments. A discharge lamp lighting device 100 shown in FIG. 1 includes a rectification unit DB, a DC power supply unit 1, an inverter unit 21, a resonance unit 22, a drive unit 3, a startup unit 4, a detection unit 5, and a state holding unit 6.

  The rectification unit DB is a known diode bridge, and full-wave rectifies the AC power input from the external AC power supply AC.

  The DC power supply unit 1 smoothes at least the output of the rectifying unit DB and outputs DC power. Further, the DC power supply unit 1 can be constituted by, for example, a smoothing capacitor (not shown) connected between the output terminals of the rectification unit DB. In this case, both ends of the smoothing capacitor are the output terminals of the DC power supply unit 1. It becomes.

  The inverter unit 21 includes a series circuit of two transistors Q1 and Q2 as switching elements connected between the output terminals of the DC power supply unit 1, and both ends of the high voltage side (high side) transistor Q1 are connected to the output terminals. It is said. Diodes D1 and D2 are connected in parallel to the transistors Q1 and Q2, respectively, and the output terminal on the low voltage side of the DC power supply unit 1 is connected to the ground.

  The resonance part 22 is connected between the output terminals of the inverter part 21 and constitutes a resonance circuit together with the discharge lamp La. Further, one end of the resonance unit 22 is connected to the non-ground side of the DC power supply unit 1. On the other hand, the other end is connected in parallel with the discharge lamp La (that is, between the filaments of the discharge lamp La) and the series circuit of the capacitor C1 and the inductor L1 connected to the connection point of the transistors Q1 and Q2 of the inverter unit 21. And a capacitor C2.

  In the drive unit 3, a transformer T1 is connected between the connection point of the transistors Q1 and Q2 of the inverter unit 21 and the resonance unit 22, and the transistors Q1 and Q2 of the inverter unit 21 are driven on and off. The transformer T1 functions as a driving transformer for driving the transistors Q1 and Q2 by self-excitation. In the drive unit 3, one end of one secondary winding of the transformer T1 is connected to the base of the transistor Q1 via the resistor R1, and the other end of the winding is connected to the connection point of the transistors Q1 and Q2. . One end of the other winding of the transformer T1 is connected to the base of the transistor Q2 via the resistor R2, and the other end of the winding is connected to the ground.

  Thus, the inverter part 21, the resonance part 22, and the drive part 3 constitute a so-called self-excited half-bridge inverter circuit as a whole.

  Further, the DC power supply unit 1 and the inverter unit 21 have a function as a high frequency power supply unit that converts a DC voltage into a high frequency voltage and supplies it to the discharge lamp La. The drive unit 3 has a function as a transmission control unit that controls the output of the high frequency power supply unit.

  The activation unit 4 activates the inverter unit 21. The starter 4 has one end of a series circuit of resistors R3 and R4 connected to the non-ground side of the DC power supply 1 via the filament of the discharge lamp La, and the other end connected to the ground. A capacitor C3 is connected in parallel to the resistor R4. The connection point between the resistor R3 and the resistor R4 is connected to the connection point of the transistors Q1 and Q2 in the forward direction with the diode D3, and is connected to the base of the transistor Q2 through the series circuit of the diac DA1 and the resistor R5. .

  Further, the detection unit 5 detects the end-of-life state (Emiless state) of the discharge lamp La and stops the operation of the inverter unit 21.

  In the detection unit 5, a series circuit of a coupling capacitor C6, a resistor R8, and a diode D4 is connected between the connection point of the discharge lamp La and the inductor L1 and the ground. The polarity of the diode D4 is forward with respect to the ground.

  A series circuit of a diode D5 and a capacitor C7 is connected between the connection point of the resistor R8 and the diode D4 and the ground. The polarity of the diode D5 is forward with respect to the connection point between the resistor R8 and the diode D4. A series circuit of a resistor R9 and a resistor R10, a series circuit of a resistor R13 and a PNP transistor Q6, and a series circuit of resistors R14 and R15 are connected in parallel to both ends of the capacitor C7. A series circuit of a resistor R11 and a PNP transistor Q5 and a series circuit of an electrolytic capacitor C8 and a resistor R16 are connected in parallel to both ends of the resistor R10. The polarity of this electrolytic capacitor C8 is such that the positive electrode is on the resistor R16 side.

  The PNP transistor Q6 has a base connected to a connection point between the resistors R14 and R15, an emitter connected to the ground, and a collector connected to the resistor R13. The PNP transistor Q5 has a base connected to a connection point between the resistor R13 and the PNP transistor Q6, an emitter connected to the ground, and a collector connected to the resistor R11. The resistor R12 has one end connected to the base of the PNP transistor Q5 and the other end connected to the ground. The connection point of the resistor R10, the resistor R11, and the electrolytic capacitor C8 is connected to the base of the transistor Q2 of the inverter unit 21 via the diac DA2.

  The state holding unit 6 receives the output of the detection unit 5 and holds the operation state of the inverter unit 21. A series circuit of a resistor R6 and a capacitor C4 is connected to both ends of the resistor R16 of the detection unit 5. The base and emitter of the NPN transistor Q3 are connected to both ends of the capacitor C4, and the collector of the PNP transistor Q4 is connected to the non-ground side which is one end of the capacitor C4.

  The collector of NPN transistor Q3 is connected to the base of PNP transistor Q4. The emitter of the PNP transistor Q4 is connected to the connection point between the resistor R3 and the resistor R4 of the starter 4, and is connected to the base of the PNP transistor Q4 through a parallel circuit of the resistor R7 and the capacitor C5. Yes.

  Next, operation | movement of the discharge lamp lighting device 100 of this embodiment is demonstrated, referring FIG.

  As shown in FIG. 2A, when the AC power supply AC is supplied at the timing indicated by time t0, a rectified voltage is generated in the DC power supply unit 1. And as shown in FIG.2 (b), when the direct current flows through the path | route of the high voltage | pressure side filament of the discharge lamp La, resistance R3, and resistance R4, the output of the starting part 4 once raises at the time t0.

  Subsequently, when the voltage of the resistor R4 exceeds the breakover voltage of the diac DA1 at time t1, a current flows through the base of the transistor Q2 of the inverter unit 21, and the transistor Q2 is turned on. When the transistor Q2 is turned on, the inverter unit 21 is activated and the discharge lamp La starts discharging. At this time, as shown in FIG. 2C, a voltage (hereinafter also referred to as a lamp voltage) is generated at both ends of the discharge lamp La. Further, as shown in FIG. 2B, since the direct current from the direct current power supply unit 1 flows through the discharge lamp La, the output of the starting unit 4 decreases. Once the inverter unit 21 is activated, a voltage is generated in the transformer T1 of the drive unit 3 so that a so-called self-oscillation operation is continued, and the discharge lamp La is lit at a high frequency.

  Subsequently, at time t2, that is, when several hours have elapsed from the start of supply of the AC power supply AC, the discharge lamp La and the discharge lamp lighting device 100 are in a stable state, and the lamp voltage decreases compared to the initial voltage. This stable state is continued between times t2 and t3.

  In the detection unit 5, the high-frequency voltage from the connection point between the discharge lamp La and the resonant inductor L1 is DC-cut by the coupling capacitor C6 of the detection unit 5, and this high-frequency voltage is half-waved to a negative potential by the diodes D4 and D5. Rectify. The half-wave rectified voltage is divided by a plurality of resistors. Here, the voltage of the resistor R10 is set as the detection voltage of the lamp voltage.

  The voltage of the resistor R10 shown in FIG. 2 (d) is a voltage obtained by dividing the negative envelope of the lamp voltage shown in FIG. 2 (c). When the discharge lamp lighting device 100 is continuously operated after the AC power supply AC is supplied, the discharge lamp La enters the initial Emires state at time t3. The initial Emires state is a boundary point between a stable state (between times t2 and t3) in which the lamp voltage is kept constant and a state in which the lamp voltage increases. In the initial state of Emiles, as shown in FIG. 2C, the lamp voltage starts to rise, and the voltage of the resistor R10 shown in FIG. 2D also increases in the negative direction.

  Thereafter, until the Emiles state of the discharge lamp La advances and time t4 is reached, the PNP transistor Q5 is kept on as shown in FIG. 2 (e), and the PNP transistor Q6 is shown in FIG. 2 (f). Remains off. Therefore, the detection voltage of the resistor R10 is affected by the resistor R11, and the voltage dividing ratio between the resistor R10 and the series circuit of the resistor R8 and the resistor R9 is low.

  At time t4, the base voltage of the PNP transistor Q6 increases in the negative direction, whereby the PNP transistor Q6 is turned on, and the charge accumulated in the base of the transistor Q5 is extracted (discharged). Therefore, the transistor Q5 is turned off, and as shown in FIG. 2D, the detection voltage of the resistor R10 is not affected by the resistor R11, and the voltage dividing ratio between the series circuit of the resistor R8 and the resistor R9 and the resistor R10 is high. Become. Then, the detection voltage of the resistor R10 exceeds the breakover voltage of the diac DA2, the diac DA2 becomes conductive, and the inverter unit 21 stops.

  Thus, the detection unit 5 detects the detection voltage based on the lamp voltage of the discharge lamp La and stops the inverter unit 21.

  When the detection voltage of the resistor R10 exceeds the breakover voltage of the diac DA2, the charge accumulated at the base of the transistor Q2 of the inverter unit 21 is extracted (discharged). At the same time, the electric charge charged in the electrolytic capacitor C8 is discharged, so that the NPN transistor Q3 of the state holding unit 6 is turned on, the PNP transistor Q4 is also turned on, and the resistance R3 and the resistance R4 of the starting unit 4 The voltage at the connection point is maintained at 0V. By operating in this way, no restart is applied to mask the starter 4, and the inverter 21 is kept stopped.

  Note that a voltage equal to the detection voltage of the resistor R10 when the PNP transistor Q6 is turned on corresponds to the first threshold value. The breakover voltage of the diac DA2 corresponds to the second threshold value. Therefore, when the detection voltage of the resistor R10 exceeds the first threshold value (in the negative direction), the detection unit 5 converts the value to a value equal to or higher than the second threshold value (in the negative direction) greater than the first threshold value. When the detection voltage of the resistor R10 is equal to or higher than the second threshold value (in the negative direction), the operation of the inverter unit 21 is stopped.

  Also, at time t5, unlike the discharge lamp lighting device 100 of this embodiment, when the transistors Q5 and Q6 are not provided and the detection voltage is not switched, the detection voltage becomes the breakover voltage of the diac DA2. It's time. Here, the difference between the lamp voltage in the stable state of the discharge lamp La and the lamp voltage when the detection unit 5 detects the Emires state (time t4) is ΔA. In this case, as shown in FIG. 2 (c), the lamp voltage in the stable state of the discharge lamp La and the lamp voltage at the time of detection of the Emires state (time t5) by the discharge lamp lighting device without switching of the detection voltage , Is represented by ΔB.

  The magnitude relationship between ΔA and ΔB is ΔA <ΔB. This means that the difference between the lamp voltage in the stable state of the discharge lamp La and the lamp voltage at the time of detecting the Emires state is smaller than in the past. Therefore, it means that the electric power inserted into the filament of the discharge lamp La becomes small before the detection of the Emiless state, and it is possible to prevent the socket from melting before the detection of the Emiless state.

  In the discharge lamp lighting device 100, for example, as shown in FIG. 3, a printed wiring board 70 on which the components of the circuit of FIG. In the example of FIG. 3, the output terminal connector CN connected to the discharge lamp La is also mounted on the printed wiring board 70 which is the same substrate. The case 71 is housed and held in a one-lamp or two-lamp apparatus body 80 as shown in FIGS. 4A and 4B to constitute the lighting apparatus 8. That is, the lighting fixture 8 includes the discharge lamp lighting device 100 and the fixture main body 80. The lighting fixture 8 and the fixture body 80 are, for example, white in order to efficiently distribute the light from the discharge lamp La.

  Further, if the electric power inserted into the filament before the detection of the Emiless state by the detection unit 5 is set to about 20 W or less, the melting of the socket can be surely prevented even in the case of the lighting fixture 8 that is relatively easy to accumulate heat. . As the lighting fixture 8 that is relatively easy to heat up, for example, a fixture having a structure in which a discharge lamp La as shown in FIG. 5 is accommodated in the fixture main body 80, or a milky white panel or the like is attached to the fixture main body 80. A device having a structure in which the discharge lamp La cannot be directly seen is conceivable.

  In order to set the power inserted into the filament to 20 W or less, the detection unit is configured such that when the power inserted into the discharge lamp La reaches approximately 20 W, the detection voltage of the resistor R10 exceeds the first threshold value. The resistance value of the resistance part (resistors R8 to R16) within 5 may be set.

  For example, in a 4-foot high-frequency fluorescent lamp FHF32, when the constant of the detection unit 5 is set so that the Emires state is detected when the lamp voltage rises by approximately 25% from the lamp voltage during stable lighting, The socket can be prevented from melting.

  That is, when the detection voltage of the resistor R10 rises by about 25% from the detection voltage in the stable state, the resistance portion (resistor R8) in the detection unit 5 is set so that the detection voltage of the resistor R10 exceeds the first threshold value. ˜R16) may be set.

  According to the discharge lamp lighting device 100 of the present embodiment as described above, the malfunction of the detection unit 5 in the initial use of the discharge lamp La is prevented, and the ambient temperature of the discharge lamp La rises so that the tube voltage of the discharge lamp La is increased. Even if it decreases, it is possible to minimize deterioration of the detection sensitivity of the Emires state. Furthermore, an inexpensive and highly safe discharge lamp lighting device can be realized.

DESCRIPTION OF SYMBOLS 100 Discharge lamp lighting device 1 DC power supply part 21 Inverter part 22 Resonance part 3 Drive part 4 Start-up part 5 Detection part 6 State holding part 70 Printed wiring board 71 Case 8 Lighting fixture 80 Instrument body AC AC power supply DB Rectification part La Discharge lamp

Claims (5)

A high-frequency power supply unit that converts a DC voltage into a high-frequency voltage and supplies it to a discharge lamp;
A detection unit for detecting the high-frequency voltage output from the high-frequency power supply unit;
With
When the detection voltage based on the high-frequency voltage exceeds a first threshold, the detection unit converts the detection voltage to a value equal to or greater than a second threshold that is greater than the first threshold, and the detection voltage of the detection unit A discharge lamp lighting device that stops the operation of the high-frequency power supply unit when is greater than or equal to the second threshold value. The discharge lamp lighting device according to claim 1, further comprising:
An oscillation control unit for controlling the output of the high-frequency power supply unit;
The high-frequency power supply unit includes two switching elements and a resonance circuit including a DC cut capacitor.
The oscillation control unit is a discharge lamp lighting device including a drive transformer for self-excitingly driving the switching element. The discharge lamp lighting device according to claim 1 or 2,
A discharge lamp lighting device in which a resistance value of the resistance portion of the detection unit is set so that the detection voltage exceeds the first threshold when the tube voltage of the discharge lamp rises by about 25% with respect to stable lighting. . The discharge lamp lighting device according to claim 1 or 2,
A discharge lamp lighting device in which a resistance value of a resistance portion of the detection unit is set so that the detection voltage exceeds the first threshold when the power inserted into the filament of the discharge lamp reaches approximately 20 W. The discharge lamp lighting device according to any one of claims 1 to 4,
An instrument body holding the discharge lamp lighting device;
A lighting fixture comprising:

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