JP5163892B2 - Discharge lamp lighting device - Google Patents

Description

  The present invention relates to a discharge lamp lighting device including a pair of lamps connected in series.

2. Description of the Related Art Conventionally, for example, a discharge lamp lighting device that continuously dims a pair of discharge lamps is known. Such a lighting device includes an inverter circuit that is connected to the DC power supply unit and lights the discharge lamps in a lump, and the discharge lamp is dimmed by controlling the operating frequency of the inverter circuit. Further, in order to determine whether or not the discharge lamp is mounted, a DC voltage from the DC power supply unit is superimposed. Further, the discharge lamp lighting device includes an end-of-life detection circuit that detects the life of each discharge lamp by detecting the voltage between both terminals of each discharge lamp, and the voltage detected by the end-of-life detection circuit is the voltage detected by each discharge lamp. Is controlled so as to stop the operation of the inverter circuit (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 8-273859 (page 7-10, FIG. 2)

  However, at the time of deep dimming lighting such as 10% or less of the all-light lighting state, the lamp current is small. For this reason, the above-described configuration in which the mounting of the lamp is detected by superimposing a DC voltage on the output from the inverter circuit not only may cause a so-called catalysis phenomenon in which the brightness of the lamp is biased, but also a half-wave discharge. There is also a problem that it is not easy to detect current, that is, to detect the end of life of the discharge lamp.

  The present invention has been made in view of these points, and an object of the present invention is to provide a discharge lamp lighting device that can reliably detect the end of life of each discharge lamp while preventing a catalysis phenomenon.

The discharge lamp lighting device according to claim 1 includes a DC voltage unit that outputs a DC voltage; a DC voltage output from the DC voltage unit is converted into a high-frequency AC voltage, and a pair of discharge lamps connected in series are collectively An inverter circuit that can be turned on; dimming control means for controlling the operating frequency of the inverter circuit according to a dimming signal from the outside; a common connected to the midpoint of each discharge lamp from the output side of the DC voltage unit comprising a resistor, separately provided on each of the respective discharge lamp, with each discharge lamp to detect whether the end of life by detecting the half-wave discharge current end-of-life of the discharge lamp, respectively, common resistor at least one half-wave of the discharge lamp by these life terminal detecting means; and each detectable life terminal detecting means mounted in the corresponding discharge lamp by a DC voltage from the DC voltage part through the Upon detection of denden flow and control means for stopping the operation of the inverter circuit; those which comprises a.

  The DC voltage unit can output a DC voltage by rectifying and smoothing the output voltage of a chopper booster circuit, for example.

  The discharge lamp is preferably a low-pressure mercury discharge lamp such as a fluorescent lamp, but is not limited thereto.

  As the inverter circuit, for example, a half bridge type including a pair of switching elements is used, but the inverter circuit is not limited thereto.

  The dimming control means can employ, for example, a PWM change method in which the operating frequency of the inverter circuit is intermittently turned on and off at a frequency lower than or higher than the frequency of the high frequency voltage.

  The predetermined dimming lighting state means, for example, when the dimming state is about 10% with respect to the all-light lighting state in which all discharge lamps are rated-lit.

  The end-of-life detection means indirectly detects a half-wave discharge current from the voltage of a capacitor charged by a resistance voltage dividing circuit in which a plurality of resistors are connected in series, for example.

  The control means is an MPU (arithmetic element) such as a microcomputer, for example, and can variably control the operating frequency of the inverter circuit corresponding to the state of the discharge lamp.

請 Motomeko 2 discharge lamp lighting apparatus described, in the discharge lamp lighting device according to claim 1, one of the pair of discharge lamp, comprising a off means for turning off the predetermined dimming lighting state, the control means When one discharge lamp is extinguished in a predetermined dimming lighting state, the detection of the half-wave discharge current by the end-of-life detection means corresponding to this discharge lamp is ignored.

  The extinguishing means is, for example, a capacitor that bypasses at least a part of the current flowing through the discharge lamp on the low potential side.

  Ignoring the detection of the half-wave discharge current by the end-of-life detection means means, for example, that the operation of the inverter circuit is not stopped even if the half-wave discharge current is detected.

According to the discharge lamp lighting device of the first aspect, there is provided a common resistor connected from the output side of the DC voltage unit to the midpoint of each discharge lamp, and the life of the half-wave discharge current at the end of the life of the discharge lamp is detected. By providing the end detection means separately for each discharge lamp, the half-wave discharge current can be detected by the end-of-life detection means for each discharge lamp without superimposing the DC voltage on the output of the inverter circuit, thereby suppressing the catalysis phenomenon. The end of life of each discharge lamp can be reliably detected , and each end of life detection means can detect the mounting of the corresponding discharge lamp by the direct current voltage from the direct current voltage section through a common resistor, It is not necessary to separately provide a configuration for detecting the mounting of the discharge lamp, and the configuration can be simplified .

According to the discharge lamp lighting apparatus 請 Motomeko 2 wherein, in addition to the effects of the discharge lamp lighting device according to claim 1, if you have to turn off the one of the discharge lamp by turning off means at a predetermined dimming lighting state Ignoring the detection of the half-wave discharge current by the end-of-life detection means corresponding to this discharge lamp, the state where the discharge lamp is turned off for dimming lighting is the state where this discharge lamp is not mounted. It is possible to prevent erroneous determination.

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

  FIG. 1 is a circuit diagram of a discharge lamp lighting device, FIG. 2 is a perspective view showing a lighting fixture equipped with the discharge lamp lighting device, FIG. 3 is a graph showing a light output change during dimming of the discharge lamp lighting device, and FIG. FIG. 5 is a flowchart of the control of the discharge lamp lighting device, and FIG. 5 is a timing chart of the operation of the power supply unit of the discharge lamp lighting device.

  In FIG. 2, reference numeral 11 denotes a lighting fixture. In this lighting fixture 11, fluorescent lamps 13 and 14 as annular discharge lamps are concentrically arranged on the fixture body 12 so as to cover the fluorescent lamps 13 and 14. A milky white shade 15 is attached to the instrument body 12.

  In the present embodiment, one of the fluorescent lamps 13 has a smaller diameter than the other fluorescent lamp 14, and therefore the rated power is set to be small. The other fluorescent lamp 14 is connected to the low potential side, that is, the ground potential side. Furthermore, the fluorescent lamps 13 and 14 are arranged on substantially the same plane, and the lighting fixture 11 is made thin.

  As shown in FIG. 1, a discharge lamp lighting device 42 (hereinafter referred to as a lighting device 42) mounted on the appliance main body 12 includes an inverter circuit in a power source unit 51 as a DC voltage unit that rectifies and smoothes a commercial AC power source e. 52 is connected, and the filaments FL1a and FL2a of the fluorescent lamps 13 and 14 are connected to the output terminal of the inverter circuit 52 via the resonance circuit 53. Further, the preheating circuit 55 of the filaments FL1a, FL1b, FL2a, and FL2b of the fluorescent lamps 13 and 14 is connected to a connection portion between the inverter circuit 52 and the resonance circuit 53. That is, the fluorescent lamps 13 and 14 are connected in series with each other. In addition, end-of-life detection circuits 56 and 57 as end-of-life detection means are connected to each of the fluorescent lamps 13 and 14, respectively. The power supply unit 51, the inverter circuit 52, the preheating circuit 55, and the end of life detection circuits 56 and 57 are connected to a digital signal processing device 58 (hereinafter referred to as a DSP 58) having functions of a dimming control means and a control means. Yes. The DSP 58 is connected to a dimming signal unit 59 for inputting a dimming signal DIM from the outside. The commercial AC power source e, the power supply unit 51, the inverter circuit 52, the resonance circuit 53, the preheating circuit 55, the end-of-life detection circuits 56 and 57, the DSP 58, the dimming signal unit 59, and the like constitute a lighting circuit LC as an operating circuit. At the same time, the lighting circuit LC and the fluorescent lamps 13 and 14 are connected to form the main circuit MC.

  The power supply unit 51 is a step-up chopper power supply having a so-called critical mode power factor correction (PFC) function that matches the phase of the input current I0 and the input voltage V0. A wave rectifier element REC1 is connected, and a boost chopper circuit 60 is connected to the output side of the full wave rectifier element REC1. In the boost chopper circuit 60, a series circuit of a chopper choke L1 that is a boosting transformer and a reverse blocking diode D1 is connected to the output side of the full-wave rectifying element REC1 and the inverter circuit 52. A first switching element as a switching element, that is, a field effect transistor (FET) Q1, which is a chopping switching element, is connected in parallel to the connection point between the chopper choke L1 and the anode of the diode D1, and the cathode of the diode D1 The electrolytic capacitor C1, which is a smoothing capacitor, is connected in parallel to the connection point between the inverter circuit 52 and the inverter circuit 52.

  The chopper choke L1 has a primary winding L1a and a secondary winding L1b, and the primary winding L1a is connected between the output side of the full-wave rectifying element REC1 and the anode of the diode D1, and the secondary winding L1a One end side of the winding L1b is connected to the ground potential side, and the other end side is connected to a set terminal of a flip-flop 61, which is a sequential circuit as a control signal generation unit, via a detection resistor R1. Therefore, the choke voltage V generated in the resistor R1 by the choke current I is input to the set terminal of the flip-flop 61 from the secondary winding L1b of the chopper choke L1.

  The field effect transistor Q1 has a drain terminal connected to the connection point between the chopper choke L1 and the anode of the diode D1, a source terminal connected to the ground potential side via the resistor R2, and a gate serving as a control terminal The terminal is connected to the output terminal of the flip-flop 61.

  Here, the flip-flop 61 is a so-called RS type, and an output terminal of an analog comparator 63 which is a comparator as an operational amplifier, that is, a comparator, is connected to a reset terminal. In this analog comparator 63, one input terminal is connected to the connection point between the drain terminal of the field effect transistor Q1 and the resistor R2, and the voltage VQ generated in the resistor R2 by the switching current IQ of the field effect transistor Q1 is input. The other input terminal is connected to the DSP 58 via a resistor R3, and the connection point with the resistor R3 is connected to the ground potential side via a capacitor C2.

  Then, with the flip-flop 61 and the analog comparator 63, etc., boost chopper circuit control means as a switching pulse generation circuit that controls the operation of the boost chopper circuit 60 based on the zero current phase of the choke current I and the switching current IQ. A certain chopping control unit 64 is configured.

  The inverter circuit 52 is a so-called half-bridge type in which field effect transistors Q2 and Q3, which are switching elements for inverters as second switching elements, are connected in series to the power supply unit 51.

  The gate terminals of the field effect transistors Q2 and Q3 are connected to the DSP 58 via a driver 65 as control means, and on / off is controlled by a signal supplied from the driver 65.

  The driver 65 turns on and off the field effect transistors Q2 and Q3 alternately at an operating frequency of about several tens of kHz to 200 kHz, for example, 50 kHz or more in the present embodiment, in accordance with the dimming PWM signal P supplied from the DSP 58. A predetermined high-frequency alternating current is generated by (switching driving).

  In the resonance circuit 53, a resonance capacitor C4 is connected in parallel between both ends of the field effect transistor Q3 via a capacitor C3 that cuts off a DC component and a resonance inductor L2 in series.

  The preheating circuit 55 includes a series circuit of a preheating transformer L3, a capacitor C5, a field effect transistor Q4 as a preheating switching element and a resistor R4 for current detection, and a connection point between the capacitor C5 and the field effect transistor Q4 and a field effect. A diode D2 is connected between the source terminal of the transistor Q2.

  In the preheating transformer L3, the primary winding L3a, the first secondary winding L3b, the second secondary winding L3c, and the third secondary winding L3d are arranged to face each other, and the primary winding L3a The connection point between the effect transistors Q2 and Q3 and the resonance capacitor C4 is connected, and the first secondary winding L3b is connected between both ends of the filament FL1a of the fluorescent lamp 13 in series with the capacitor C6. The second secondary winding L3c is connected in series with the capacitor C7 between the filament FL1b of one of the fluorescent lamps 13 and the filament FL2b of the other fluorescent lamp 14, and the third secondary winding L3d is connected to the capacitor C8. Is connected between both ends of the filament FL2a of the other fluorescent lamp.

  Here, the filament FL1b of one fluorescent lamp 13 and the filament FL2b of the other fluorescent lamp 14 are electrically connected to each other at one end side, and a second secondary winding L3c and a capacitor C8 are connected in series between the other end side. The circuit is electrically connected. Further, a bypass capacitor C9 as a light-off means is connected to one end of the filament FL1b of one fluorescent lamp 13 and the filament FL2b of the other fluorescent lamp. Furthermore, the other end side of the filament FL2b of the other fluorescent lamp 14 is electrically connected to the ground potential side via a DC cut capacitor C10.

  The bypass capacitor C9 is connected between one end side of the filaments FL1b and FL2b and a connection point between the capacitor C8 and one end side of the filament FL2a of the other fluorescent lamp 14, and has a capacitance equivalent to stray capacitance, for example, about 220 pF. And has a function of bypassing a part of the current that is about to flow to the other fluorescent lamp. For this reason, the other fluorescent lamp 14 is bypassed to the bypass capacitor C9 with respect to the current flowing through the other fluorescent lamp 14 when the dimming step by the dimming signal DIM output from the dimming signal unit 59 becomes deep. When the current ratio is relatively increased, it is set to turn off when it is set to a predetermined dimming state, for example, 10% or less when all the fluorescent lamps 13 and 14 are turned on. The bypass capacitor C9 may be formed by physically connecting a capacitor, or may be a stray capacitance formed between the filaments FL2a and FL2b of the other fluorescent lamp 14.

  In the field effect transistor Q4, a gate terminal which is a control terminal is connected to the DSP 58, and switching control is performed by a preheating PWM signal supplied from the DSP 58.

  One end-of-life detection circuit 56 detects a half-wave discharge current at the end of the life of one fluorescent lamp 13, and is one end side of the filament FL1a of the capacitor C4 which is the output side of the resonance circuit 53 and one fluorescent lamp 14. A series circuit, which is a resistance voltage dividing circuit of resistors R5 and R6, is connected between the connection point of the resistor R5 and R6, and a capacitor C11 to be charged is connected to the ground potential at the connection point of the resistors R5 and R6. Connected between.

  The other end-of-life detection circuit 57 detects a half-wave discharge current at the end of life of the other fluorescent lamp 14, and is connected to the connection point between the capacitor C10 and the other end of the filament FL2a of the other fluorescent lamp 14. A series circuit which is a resistance voltage dividing circuit of resistors R7 and R8 is connected between the ground potential and a capacitor C12 to be charged is connected between the ground potential and a connection point of these resistors R7 and R8.

  The end-of-life detection circuits 56 and 57 include a resistor R11 connected from the output side of the power supply unit 51 to one end side of the filament FL1b of one fluorescent lamp 13, which is the middle point of the fluorescent lamps 13 and 14. A resistor R12 connected between a connection point between R11 and one end of the filament FL1a and a capacitor C6 and the other end of the filament FL1a of one fluorescent lamp 13, and a filament FL2a of the capacitor C7 and the other fluorescent lamp 14 A resistor R13 connected in common with one end side is provided.

  The DSP 58 is an MPU (arithmetic element) such as a so-called microcomputer that performs digital signal processing, and a voltage setting unit 71 that is a reference voltage setting unit as a reference waveform setting unit connected to an input terminal of the analog comparator 63. Preheating circuit controller 72 for controlling switching of field effect transistor Q4 of preheating circuit 55, lighting circuit LC and fluorescent lamp by detecting at least one of discharge current, ie, lamp current IL, and discharge voltage, ie, lamp voltage VL As a state detecting unit 73 having a function of a state detecting means for detecting the operating states of 13 and 14 (the operating state of the main circuit MC), and a signal generating means for generating a PWM signal P for controlling the operation of the field effect transistors Q2 and Q3. The lifespan of the fluorescent lamps 13 and 14 based on outputs from the control signal generation unit 74 and the lifespan detection circuits 56 and 57 as inverter circuit control units In addition, a determination unit 75 as a determination unit for determining whether or not the fluorescent lamps 13 and 14 are mounted is integrally provided therein, and a ROM, a RAM, an I / O port as an interface (not shown), and the like are provided. Each has.

  The DSP 58 integrally including the voltage setting unit 71, the preheating circuit control unit 72, the control signal generation unit 74, the determination unit 75, and the like means that the DSP 58 shares the software processing part.

  The voltage setting unit 71 is a software unit having a function of power supply voltage detection means for detecting at least one of the input voltage V0 and the output voltage V1 of the power supply unit 51, and at least one of the detected voltages V0 and V1 Based on the reference voltage VTH, a reference voltage VTH which is a reference voltage for comparison of the analog comparator 63 and is a PWM signal is set.

  Specifically, in the present embodiment, the reference voltage VTH is generated by a rectified power supply voltage waveform that becomes the reference waveform SW so as to be turned off depending on the magnitude of the voltage VQ input to the analog comparator 63 and the reference voltage VTH. The switching pulse SP of the field effect transistor Q1, which is a control signal for feedback control, that is, a PWM control signal, is set so that the output voltage V1 approaches a desired target value. The reference waveform SW can be varied corresponding to at least one of the output voltage V1 (output current I1) from the power supply unit 51 and the power supply voltage, for example.

  In other words, the lighting device 42 generates the reference voltage VTH for switching for PFC control of the power supply unit 51 by the DSP 58, and generates the switching pulse SP for switching the field effect transistor Q1 by using the flip-flop 61 or the analog comparator. It is generated by a chopping control unit 64 configured by hardware such as 63.

  The preheating circuit control unit 72 is a software unit having a function of preheating current detection means for detecting the preheating current IP of the preheating circuit 55, and monitors the preheating current IP of the preheating circuit 55 while detecting the lamp detected by the state detection unit 73. The gate terminal of the field effect transistor Q4 of the preheating circuit 55 is set so that the optimum preheating condition, that is, the target value is set so as to follow the change of at least one of the current IL and the lamp voltage VL, and the preheating current IP approaches the target value. PWM signal PP for preheating to be supplied to is generated.

  The state detection unit 73 is an A / D converter that is an arithmetic unit that converts at least one of the lamp current IL and the lamp voltage VL, which are analog signals, into digital frequency data corresponding to the lamp current IL and the lamp voltage VL. And outputs at least one of the A / D converted lamp current IL and lamp voltage VL to the preheating circuit controller 72 or the control signal generator 74. The detection timing of the lamp current IL or lamp voltage VL in this state detection unit 73 is, for example, at least one analog signal in the main circuit MC such as a power supply voltage waveform or a voltage across the resonance capacitor C4, or The timing is synchronized with the peak phase of the lamp current IL or the lamp voltage VL based on predetermined frequency data which is a digital signal calculated based on the lamp current IL or the lamp voltage VL detected by the state detector 73. . In the present embodiment, for example, since the state detection unit 73 has a function of an A / D converter, it is based on predetermined frequency data that is a digital signal calculated based on the lamp current IL, the lamp voltage VL, and the like. Thus, the detection timing of the lamp current IL or the lamp voltage VL is determined.

  The ROM stores in advance various programs executed by each part of the DSP 58, for example, the voltage setting unit 71, the preheating circuit control unit 72, the control signal generation unit 74, and the like.

  In the RAM, various digital values detected by the state detection unit 73 and the like are stored in areas assigned to them.

  The dimming signal unit 59 is a signal output unit 76 that outputs a PWM dimming signal of about 100 Hz, for example, and a rectifying unit that rectifies the PWM dimming signal output from the signal output unit 76 and inputs the rectified signal to the DSP 58. And a full-wave rectifying element REC2.

  The control signal generation unit 74 indirectly detects the lighting state of the fluorescent lamps 13 and 14 detected by the state detection unit 73, that is, at least one of the lamp current IL and the lamp voltage VL, by the end-of-life detection circuits 56 and 57. This is a software unit that generates a PWM signal P having a predetermined frequency based on the lifetime of the fluorescent lamps 13 and 14 or the dimming signal DIM output from the dimming signal unit 59. As shown in FIG. 3, the dimming characteristics of the PWM signal P generated by the control signal generator 74 are as follows: the total light output of the fluorescent lamp 13 is A1, the light output of the fluorescent lamp 14 is A2, and the fluorescent lamp The light output A is the sum of the light outputs A1 and A2 of 13 and 14.

  The determination unit 75 determines whether or not the fluorescent lamps 13 and 14 are at the end of their life by comparing the outputs from the end of life detection circuits 56 and 57 with a predetermined threshold value in a lighting state. It is determined whether or not the fluorescent lamps 13 and 14 are mounted by comparing the outputs from the end-of-life detection circuits 56 and 57 with a predetermined threshold value in a lighting state. In addition, the determination unit 75 is provided with a mounting state counter (not shown) corresponding to each of the fluorescent lamps 13 and 14. These mounted state counters are used to determine whether or not the fluorescent lamps 13 and 14 are in a mounted state by being cleared when it is determined that the fluorescent lamps 13 and 14 are in a mounted state. Each determination by the determination unit 75 is always performed in a power-on state.

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

  First, the end-of-life detection control of the fluorescent lamps 13 and 14 and the detection control of whether or not the fluorescent lamps 13 and 14 are mounted in the control signal generation unit 74 of the DSP 58 will be described with reference to the flowchart shown in FIG. To do.

  The determination unit 75 of the DSP 58 first determines whether or not the lighting fixture 11 is in the lighting operation (step S1).

  For this determination, outputs from the end of life detection circuits 56 and 57 are used. That is, when both the fluorescent lamps 13 and 14 are lit, the impedance of these fluorescent lamps 13 and 14 becomes very small, the current of the resistor R12 and the current of the resistor R13 are bypassed, and the filament FL1a, Since the resistance loss in FL1b, FL2a, and FL2b is also very small, the voltages VC11 and C11 and C12 of the capacitors C11 and C12 that are divided and charged by the resistors R5 and R6 and the resistors R7 and R8 of the life end detection circuits 56 and 57, respectively. Since VC12 becomes very small, the determination unit 75 of the DSP 58 can determine that the light is on.

  Similarly, when only one of the fluorescent lamps 13 is lit, such as a dimming state of 10% or less when all the lights are lit, the impedance of one of the fluorescent lamps 13 becomes very small, and the current of the resistor R12 In the other fluorescent lamp 14, since the current of the resistor R13 is bypassed by the bypass capacitor C9, the voltages VC11 and VC12 of the capacitors C11 and C12 are very small in the same manner as described above. The determination unit 75 can determine that the lighting is in progress.

  If it is determined in step S1 that the fluorescent lamps 13 and 14 are lit, it is determined whether one of the high-pressure fluorescent lamps 13 is at the end of its life (step S2).

  For this determination, the output from one end of life detection circuit 56 is used. That is, when one of the fluorescent lamps 13 is mounted at the end of its life, either one of the filaments FL1a and FL1b is in an emitterless state, causing a rectifying action on one of the fluorescent lamps 13 and causing a half-wave discharge. When the current is generated, the voltage is divided by the resistors R5 and R6 of one end of life detection circuit 56, and the capacitor C11 is charged. Therefore, the determination unit 75 determines whether or not the voltage VC11 of the charged capacitor C11 is larger than the preset predetermined voltage a and smaller than the voltage b, that is, whether a <VC11 <b. It can be determined whether one of the fluorescent lamps 13 is at the end of its life.

  If it is determined in step S2 that one of the fluorescent lamps 13 is at the end of its life, the output from the determination unit 75 stops the PWM signal P output from the control signal generation unit 74 to the driver 65 and stops oscillation. Processing is performed (step S3). Thereafter, the determination unit 75 of the DSP 58 determines whether or not the other fluorescent lamp 14 is turned off, that is, whether or not the dimming lighting state is below a predetermined level of dimming lighting state, for example, 10% or less when all light is on. If it is determined (step S4) and it is determined that the dimming lighting state is below the predetermined level, the process returns. If it is determined in step S4 that the dimming lighting state is not lower than the predetermined level, it is determined whether the other fluorescent lamp 14 on the low pressure side is at the end of its life (step S5). If it is determined in step S2 that one of the fluorescent lamps 13 is not at the end of its life, the process proceeds to step S4 as it is.

  For the determination in step S5, the output from the other end of life detection circuit 57 is used. Similar to the determination in step S2, that is, when the other fluorescent lamp 14 is mounted in the state of reaching the end of its life, one of the filaments FL2a and FL2b is in an emitterless state, and the other fluorescent lamp 14 As a result of the rectifying action and the half-wave discharge current, the voltage is divided by the resistors R7 and R8 of the other end of life detection circuit 57 and the capacitor C12 is charged. Therefore, the determination unit 75 determines whether or not the voltage VC12 of the charged capacitor C12 is larger than the predetermined voltage c set in advance and smaller than the voltage d, that is, whether c <VC12 <d. It can be determined whether the other fluorescent lamp 14 is at the end of its life.

  If it is determined in step S5 that the other fluorescent lamp 14 is at the end of its life, the PWM signal P output to the driver 65 is stopped, oscillation stop processing is performed (step S6), and the process returns. If it is determined in step S5 that the other fluorescent lamp 14 is not at the end of its life, the process returns as it is.

  On the other hand, if it is determined in step S1 that the fluorescent lamps 13 and 14 are not lit, it is determined whether or not one of the high-pressure fluorescent lamps 13 is mounted (step S7).

  For this determination, the output from one end-of-life detection circuit 56 is used as in step S2. For example, when one of the fluorescent lamps 13 is mounted, the resistance R11, R12, the filament FL1a acting as a resistance, and the resistance R5, R6 distribution circuit are connected to the DC voltage from the power supply unit 51. Thus, the voltage is divided by the resistors R11 and R12, the filament FL1a and the resistors R5 and R6 and the capacitor C11 is charged. On the other hand, when one of the fluorescent lamps 13 is not mounted, the distribution circuit is It is not formed and the capacitor C11 is not charged. Therefore, the determination unit 75 can determine whether one of the fluorescent lamps 13 is mounted by detecting the voltage of the charged capacitor C11.

  If it is determined in step S6 that one of the fluorescent lamps 13 is mounted, the determination unit 75 of the DSP 58 clears the mounting state counter on the one fluorescent lamp 13 side (step S8). Next, the determination unit 75 of the DSP 58 determines whether one of the fluorescent lamps 13 is attached (step S9). If it is determined in step S7 that one of the fluorescent lamps 13 is not mounted, the process proceeds directly to step S9.

  For the determination in step S9, the output from the other end of life detection circuit 57 is used as in step S5. For example, when the other fluorescent lamp 14 is mounted, the resistor R11, the filament FL2b that acts as a resistor, the resistor R13, the filament FL2a that acts as a resistor, and the resistor R7, with respect to the DC voltage from the power supply unit 51, By connecting the distribution circuit of R8, the voltage is divided by the resistor R11, the filament FL2b, the resistor R13, the filament FL2a and the resistors R7 and R8 to charge the capacitor C12, whereas the other fluorescent lamp 14 When not mounted, the distribution circuit is not formed, and the capacitor C12 is not charged. Accordingly, the determination unit 75 can determine whether or not the other fluorescent lamp 14 is mounted by detecting the voltage of the charged capacitor C12.

  Further, when it is determined in step S9 that the other fluorescent lamp 14 is mounted, the determination unit 75 of the DSP 58 clears the mounting state counter on the other fluorescent lamp 14 side (step S10) and returns. On the other hand, if it is determined in step S9 that the fluorescent lamp 14 is not mounted, the process returns.

  The operation when it is determined by the above control that the fluorescent lamps 13 and 14 are mounted in a state that is not at the end of their life (when the mounting state counter is cleared) will be described.

  In the power supply unit 51, the lighting device 42 generates the switching pulse SP by the operation of the flip-flop 61 to switch the field effect transistor Q1, and improves the power factor by matching the phases of the input voltage V0 and the input current I0. .

  Specifically, as shown in FIGS. 1 and 4, when the field effect transistor Q1 is turned on by a starting circuit (not shown) or the like, a linearly increasing current flows through the chopper choke L1 (diode D1). A choke current I flows through the secondary winding L1b of the chopper choke L1, and electromagnetic energy is accumulated in the chopper choke L1. At the same time, when the voltage VQ (≧ reference voltage VTH) generated by the resistor R2 due to the switching current IQ when the field effect transistor Q1 is turned on is input to the analog comparator 63, the reset voltage VR ( = Voltage VQ) is input, and the switching pulse SP that is off from the output terminal of the flip-flop 61 is supplied to the gate terminal of the field effect transistor Q1 and the field effect transistor Q1 is turned off, so that it accumulates in the chopper choke L1. The released electromagnetic energy is released, and a linearly decreasing current flows through the chopper choke L1 (diode D1).

  By repeating this operation, an output current I1 is formed using the waveform of the input voltage V0, that is, the reference waveform SW which is a sine waveform subjected to full-wave rectification, as an envelope.

  The output voltage V1 generated by the power supply unit 51 is converted into a high-frequency AC voltage by operating the field effect transistors Q2 and Q3 of the inverter circuit 52 at a predetermined frequency such as 50 kHz and a predetermined on-duty, for example. .

  By this high frequency AC voltage, the resonance circuit 53 resonates and a resonance current flows, and the field effect transistor Q4 is switched by the preheating PWM signal PP having a predetermined frequency generated by the preheating circuit control unit 72. A preheating current IP flows through the secondary windings L3b, L3c, and L3d of the preheating transformer L3 to preheat the filaments FL1a, FL1b, FL2a, and FL2b of the fluorescent lamps 13 and 14, respectively.

  Then, by preheating the filaments FL1a, FL1b, FL2a, FL2b, a predetermined starting voltage is applied between the filaments FL1a, FL1b and between the filaments FL2a, FL2b, and the fluorescent lamps 13, 14 are turned on (started). 14 is lit steady.

  When dimming the fluorescent lamps 13 and 14 thus lit, the drive frequency for driving the inverter circuit 52 by inputting the PWM signal P from the control signal generation unit 74 of the DSP 58 to the driver 65 of the lighting device 42 is variable. To do. By increasing or decreasing the drive frequency of the inverter circuit 52, the high frequency power from the inverter circuit 52 is suppressed or increased, the lamp current IL is suppressed or increased, and the fluorescent lamps 13 and 14 are dimmed. .

  The operating frequency of the inverter circuit 52, that is, the frequency of the PWM signal P is determined by the control signal generation unit 74 at least one of the lamp current IL and the lamp voltage VL detected by the state detection unit 73, or the dimming signal unit 59. Is set based on the dimming signal DIM output from the.

  As shown in FIG. 1 and FIG. 3, when the dimming degree is set to a predetermined dimming state, for example, 10% or less when all light is lit, by the dimming signal DIM output from the dimming signal unit 59. When a part of the lamp current IL is bypassed by the bypass capacitor C9, the other fluorescent lamp 14 is turned off (light output A2), and only one fluorescent lamp 13 is turned on.

  Therefore, in a dimming state of 10% or less when all the lights are lit, the inverter circuit 52, the DSP 58, and the like perform dimming control on only one of the fluorescent lamps 13.

  In the preheating circuit 55, the preheating current is set to the target value set by the preheating circuit control unit 72 so as to follow the lamp current IL, the lamp voltage VL, the lamp power, or the ambient temperature change detected by the state detection unit 73. The field effect transistor Q4 is switched by the preheating PWM signal PP generated so that the IP approaches, thereby optimizing the preheating amount during lighting that varies depending on the types of fluorescent lamps 13 and 14 and variations in the manufacturing process. To do.

  As described above, by connecting the end-of-life detection circuits 56 and 57 for detecting the half-wave discharge current at the end of the life of the fluorescent lamps 13 and 14 from the output side of the power supply unit 51, the DC voltage is supplied to the inverter circuit 52. Because the half-wave discharge current can be detected by the end-of-life detection circuits 56 and 57 for each fluorescent lamp 13 and 14 without being superimposed on the output, the end of life of each fluorescent lamp 13 and 14 can be reliably detected while suppressing the cataphoresis phenomenon. .

  That is, of the fluorescent lamps 13 and 14 connected in series, a bypass capacitor C9 that bypasses a part of the high-frequency current is connected in parallel to only the fluorescent lamp 14, and this bypass capacitor C9 allows all light to pass. In a predetermined dimming state of 10% or less at the time of lighting, the fluorescent lamp 14 is turned off, and when the light output is small, only one of the fluorescent lamps 13 is dimmed and controlled, for example, each of the fluorescent lamps 13, 14 In this embodiment that enables fine dimming control without complicating the configuration, such as by providing an inverter circuit that controls lighting, etc., the current in such dimming state is small, and the DC voltage is converted into an inverter circuit. When a direct current flows through the fluorescent lamps 13 and 14 by being superimposed on the output side of 52, not only the catalysis phenomenon is likely to occur, but also it is not easy to detect the half-wave discharge current. For this reason, one lifetime detection circuit 56 is connected to one fluorescent lamp 13, and the other lifetime detection circuit 57 is connected to the other fluorescent lamp 14. Thus, the end of life of each of the fluorescent lamps 13 and 14 can be reliably detected.

  In addition, since the end of life detection circuits 56 and 57 can detect the mounting of the corresponding fluorescent lamps 13 and 14, respectively, it is not necessary to separately provide a configuration for detecting the mounting of the fluorescent lamps 13 and 14. It can be simplified.

  Further, when the other fluorescent lamp 14 is turned off by bypassing the current by the capacitor C9 in a predetermined dimming lighting state, the half-wave discharge current is detected by the end-of-life detection circuit 57 corresponding to the fluorescent lamp 14. Is ignored by the determination unit 75 of the DSP 58, so that it is possible to prevent erroneous determination of a state in which the other fluorescent lamp 14 is turned off for dimming and lighting as a state in which the fluorescent lamp 14 is not mounted.

  In the above-described embodiment, a capacitor similar to the bypass capacitor C9 may be connected in parallel to a lamp having a small rated power, that is, a lamp disposed inside.

  The power supply unit 51 is not limited to the above configuration as long as it can output a DC voltage.

  Further, the configuration of the resonance circuit 53, the preheating circuit 55, etc., and the control thereof are not limited to the above configuration and control.

It is a circuit diagram of a discharge lamp lighting device showing an embodiment of the present invention. It is a perspective view which shows the lighting fixture provided with the discharge lamp lighting device same as the above. It is a graph which shows the light output change at the time of light control of a discharge lamp lighting device same as the above. It is a timing chart of operation | movement of the power supply part of a discharge lamp lighting device same as the above. It is a flowchart of control of a discharge lamp lighting device same as the above.

13, 14 Fluorescent lamps as discharge lamps
42 Discharge lamp lighting device
51 Power supply as DC voltage
52 Inverter circuit
56, 57 End of life detection circuit as end of life detection means
58 Digital signal processing device having dimming control means and functions of control means
C9 Bypass capacitor as a light-off means
R11 resistor

Claims (2)

A DC voltage section for outputting a DC voltage;
An inverter circuit capable of converting a direct current voltage output from the direct current voltage unit into a high frequency alternating current voltage and collectively lighting a pair of discharge lamps connected in series;
Dimming control means for controlling the operating frequency of the inverter circuit according to a dimming signal from the outside;
A common resistor connected to the midpoint of each discharge lamp from the output side of the DC voltage part, separately provided, respectively for each discharge lamp, detecting the half-wave discharge current end-of-life of the discharge lamp, respectively Life detecting means for detecting whether each discharge lamp is at the end of its life and capable of detecting mounting of the corresponding discharge lamp by a direct current voltage from a direct current voltage section via a common resistor ;
Upon detecting at least one of the half-wave discharge current of the discharge lamp by these life terminal detecting means and control means for stopping the operation of the inverter circuit;
A discharge lamp lighting device comprising: A light-off means for turning off one of the pair of discharge lamps in a predetermined dimming lighting state;
The control means ignores detection of the half-wave discharge current by the end-of-life detection means corresponding to the discharge lamp when one of the discharge lamps is turned off in a predetermined dimming lighting state. Item 2. A discharge lamp lighting device according to Item 1.

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