JP2006073441A - High-pressure discharge lamp lighting device and illumination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to detect abnormalities before start-up of a circuit, even in case a capacity of an electrolytic capacitor of a half-bridge inverter circuit differs from an initial value by end of life or abnormalities. <P>SOLUTION: The lighting device supplies a required power to a high-pressure discharge lamp DL with the use of the half-bridge inverter circuit by alternately repeating a first period of turning on/off a switching element Q1 at a frequency f1 and a second period of turning on/off a switching element Q2 at a frequency f2 at a frequency lower than the first and the second frequencies f1, f2. It is provided with a first detecting means 11 for determining a control frequency of one of the switching elements, and a second detecting means 12 for determining a control frequency of the other switching element. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a high-pressure discharge lamp lighting device that uses a half-bridge inverter to light a high-pressure discharge lamp with a rectangular wave at a low frequency, and an illumination device using the same.

  FIG. 12 is a circuit diagram of a conventional high pressure discharge lamp lighting device (Japanese Patent No. 2948600), and FIGS. 13 and 14 are explanatory diagrams of the operation of the device. The conventional high pressure discharge lamp lighting device shown in FIG. 12 includes a DC power supply 4 having a series circuit of switching elements (MOS FETs in the figure) Q1 and Q2 and a series circuit of two (electrolytic) capacitors C1 and C2 having the same capacity. An inductor L1 and a lamp (high pressure discharge lamp) DL connected in parallel between the output terminals of the switching elements Q1 and Q2 and the connection points of the capacitors C1 and C2, A capacitor C3 connected in parallel with the lamp DL, a high-voltage pulse generation circuit 2 inserted in series between the inductor L1 and the lamp DL so as to be in parallel with the capacitor C3, and switching elements Q1 and Q2 are shown in FIG. 14 and a control circuit 1 for controlling as shown in FIG.

  The DC power supply 4 detects a diode bridge DB that full-wave rectifies the AC voltage of the commercial AC power supply AC into a DC voltage, a step-up chopper 41 that includes an inductor L4, a switching element Q4, and a diode D4. The control circuit 42 is configured to perform on / off control of the switching element Q4 so as to have a predetermined voltage value.

  The high-voltage pulse generation circuit 2 includes a pulse generation circuit and a step-up pulse transformer, and applies a high-voltage pulse voltage to the lamp DL when the discharge lamp is not lit.

  The voltage detection circuit 11 detects the voltage of the lamp DL, and the current detection circuit 14 detects the current of the lamp DL from the resistor R1. As shown in FIGS. 13 and 14, the control circuit 1 performs switching control of the switching elements Q1 and Q2 to supply low-frequency rectangular wave power with a low-frequency rectangular wave voltage to the lamp DL. The power detection circuit 15 calculates the power required for the lamp DL from the detection results of the voltage detection circuit 11 and the current detection circuit 14, and the drive circuit IC2 drives the switching elements Q1 and Q2 according to the calculation result. ing.

  When the lamp DL is not lit, the switching elements Q1 and Q2 are alternately turned off at a low frequency as shown in FIG. 13, and the switching element Q1 is turned on / off at a high frequency when the switching element Q2 is turned off as in the period T1. The switching element Q2 is turned on / off at a high frequency when the switching element Q1 is turned off as in the period T2. As a result, a rectangular wave voltage VDL is generated at a low frequency, and a high voltage pulse voltage Vp of several KV of the high voltage pulse generation circuit 2 is superimposed on the voltage DL and applied to the lamp DL.

Thereafter, when the lamp DL is turned on and started, as shown in FIG. 14, appropriate rectangular wave AC power is supplied to the lamp DL by the same switching control as described above. Here, the high frequency is about several tens of KHz, and the low frequency is a frequency (usually several tens to several hundreds Hz) of a period obtained by adding the periods T1 and T2. Note that Patent Document 2 (Japanese Patent Laid-Open No. 2001-68277) proposes that the ON widths of the switching elements Q1 and Q2 in the periods T1 and T2 are made different.
Japanese Patent No. 2948600 JP 2001-68277 A

  In the above-described prior art, when the switching elements Q1 and Q2 are chopped as usual in a state where one of the electrolytic capacitors C1 and C2 has lost its capacity due to life or abnormality, the amount of charging current to the capacitor having lost capacity decreases. Therefore, the power supplied to the lamp alternates in an unbalanced manner, or the design capacity balance of the electrolytic capacitor is disrupted as shown in FIG. 15, and the voltage concentrates on one side, leading to the breakdown voltage of the electrolytic capacitor in which the voltage is concentrated. There was also a possibility.

  As shown in FIG. 13, the voltage that can be applied to the lamp DL when not lit is half of the output voltage E of the DC power supply 4 (the voltage applied to the series circuit of the capacitors C1 and C2 in FIG. 12). Therefore, a no-load voltage of about 250 V to about 450 V (voltage applied to both ends of the lamp DL when not lit) required to smoothly shift from glow discharge to arc discharge after the start of the lamp DL is obtained. For this reason, it is necessary to increase the withstand voltage of the components constituting the DC power supply 4.

  The present invention has been made in view of the above circumstances, and even if the capacity balance between the two electrolytic capacitors responsible for the upper and lower power supplies of the half-bridge inverter circuit is lost and is different from the initial setting value, the upper and lower electrolytic capacitors are generated. In the unlikely event that the capacity collapses beyond control, it is possible to stop the inverter by detecting it, and arc discharge from glow discharge immediately after the lamp is lit An object of the present invention is to provide a high-pressure discharge lamp lighting device capable of realizing the voltage required for smooth transition to the above without increasing the breakdown voltage of the components, and realizing these with a small number of components and a small component mounting area.

  In the high pressure discharge lamp lighting device of the present invention, in order to solve the above problems, as shown in FIG. 1, an inverter circuit that obtains a rectangular wave AC output by alternating the DC output of the DC power supply Vs is provided, The inverter circuit is connected in parallel to a series circuit of first and second capacitors C1, C2 connected between output terminals of the DC power supply Vs and a series circuit of first and second capacitors C1, C2. A series circuit of first and second switching elements Q1, Q2 and a control circuit 1 for switching control of the first and second switching elements Q1, Q2 are provided, and the first and second capacitors C1, C2 are connected. Between the point and the connection point of the first and second switching elements Q1 and Q2, at least a series connection circuit of the high-pressure discharge lamp DL and the inductor L1, and a third capacitor connected in parallel to the high-pressure discharge lamp DL. C3, and a first period during which the first switching element Q1 on the high potential side of the DC power supply Vs is turned on / off at the first frequency f1 and a second period on the low potential side of the DC power supply Vs. The second period in which the switching element Q2 is turned on / off at the second frequency f2 is alternately repeated at a frequency lower than the first and second frequencies f1 and f2, whereby desired power is supplied to the high-pressure discharge lamp DL. In the lighting device to be supplied, the control circuit 1 detects the lamp voltage of the high-pressure discharge lamp DL, and determines the control frequency f1 of one switching element Q1, and the first or second detection means 11 And a second detector 12 for detecting a voltage of at least one capacitor C2 and determining a control frequency f2 of the other switching element Q2. Note that the first detection unit 11 may control the frequency f2 of the switching element Q2, and the second detection unit 12 may control the frequency f1 of the switching element Q1. The second detection unit 12 may detect the voltage of the capacitor C1 on the high potential side.

  According to the present invention, even when the capacity of the electrolytic capacitor differs from the initial value due to life or abnormality, abnormality detection is possible before the inverter circuit is started. Even when an abnormality such as capacity loss occurs in the electrolytic capacitor while the lamp is lit, the distribution of the voltages generated in the upper and lower two electrolytic capacitors can be maintained at a desired voltage.

(Embodiment 1)
FIG. 1 is a circuit diagram of a high pressure discharge lamp lighting device according to Embodiment 1 of the present invention. This lighting device is connected in parallel to a DC power source Vs, a power switch Qs for turning on / off the DC power source Vs, and a series circuit of electrolytic capacitors C1, C2 having the same capacity forming a half-bridge inverter circuit. Inductor L1 inserted between a series circuit of switching elements Q1 and Q2 (in the example, an FET but may be a transistor) and a connection point between capacitors C1 and C2 and a connection point between switching elements Q1 and Q2 of the half-bridge inverter circuit , The lamp DL, the smoothing capacitor C3, the control circuit 1 for controlling the switching of the switching elements Q1 and Q2, and the high voltage pulse generating circuit 2 for applying a pulse voltage of several KV between the lamp electrodes at the start to break down the lamp DL. It consists of. The control circuit 1 detects a lamp voltage to determine the frequency f1 of the switching element Q1, a Vla detection circuit 11 that detects the voltage Vc2 of the capacitor C2 and determines the frequency f2 of the switching element Q2, and A first period T1 in which the switching element Q1 is turned on / off at the frequency f1 and a second period T2 in which the switching element Q2 is turned on / off at the frequency f2 are switched at a frequency lower than the respective frequencies f1, f2. A low frequency generation circuit 13, AND circuits A1 and A2, and an inverting circuit N1 are provided. The outputs of the AND circuits A1 and A2 are supplied to the switching elements Q1 and Q2 via the drive circuit IC2. The high voltage pulse generation circuit 2 includes an igniter circuit IG for generating a pulse voltage and a pulse transformer PT for boosting the pulse voltage. The high voltage pulse voltage generated in the secondary winding of the pulse transformer PT at the time of start-up is a capacitor. It is applied to both ends of the lamp DL via C3. Capacitor C3 and inductor L1 constitute a low-pass filter of a step-down chopper circuit.

Until the high-pressure discharge lamp reaches a stable lighting state from a non-lighting state, the lighting device is roughly divided into three processes shown in FIG.
1) No-load mode: The lamp is in a non-lighting state, and a pulse voltage for dielectric breakdown is applied between the high-voltage pulse generation circuit 2 and the electrode of the lamp DL.
2) Start-up mode: When the lamp DL breaks down due to the pulse voltage, an arc discharge occurs through a glow discharge. In the process from immediately after the start of the arc discharge until the temperature in the arc tube is equalized and stabilized, the lamp voltage Vla is It gradually rises over several minutes from a low voltage of several volts to a stable voltage of several tens of volts.
3) Stable lighting mode: A few minutes after the lamp is lit, the temperature in the arc tube of the lamp DL rises to a stable state, and the lamp voltage Vla becomes almost constant.

  Hereinafter, the operation in the above three modes of the high pressure discharge lamp lighting device of FIG. 1 will be described in detail.

《No load mode》
When the power switch Qs is turned on and the DC power supply Vs is connected to the inverter circuit, charging to the electrolytic capacitors C1 and C2 starts from the timing of “Qs on” in FIG. As a result, voltages Vc1 and Vc2 are generated in the capacitors C1 and C2, respectively. After the power switch Qs is turned on, the Vc detection circuit 12 detects the voltage Vc2 of the electrolytic capacitor C2 after a predetermined time t1, and compares it with the determination value. At this time, the determination value is a value for confirming that the voltages generated in the capacitors C1 and C2 do not exceed the respective withstand voltages. For example, 250V is normally generated in the electrolytic capacitors C1 and C2 having a withstand voltage of 300V. In the designed circuit, it is confirmed whether the lower limit judgment value of 200V <Vc2 <300V or not. (The Vc detection circuit 12 generates voltages Vc1 and Vc2 that are inversely proportional to the non-uniform ratio when the capacitances of the electrolytic capacitors C1 and C2 are set non-uniformly as described in the second embodiment. If it is, it is determined as normal.)

  When the Vc determination result is at an abnormal level equal to or higher than a predetermined value or lower than the predetermined value, the high pressure discharge lamp lighting device does not start the lamp DL. At this time, a means for notifying the outside of the abnormality may be provided. If the Vc determination result is normal, the operation proceeds to the ignition operation at t2 in FIG.

  When the Vc determination result is normal, a drive signal is output from the control circuit 1, and a period T1 during which the switching element Q1 is chopped at a high frequency f1 of several tens to several hundreds of kilohertz (the switching element Q2 is kept off during this time) The period T2 in which the switching element Q2 is chopped at a high frequency f2 of several tens to several hundreds of kilohertz (the switching element Q1 is kept off during this period) is alternately repeated at a low frequency of several tens to several hundreds of hertz. As a result, a rectangular wave voltage of several hundred volts in which the voltage Vc1 and the voltage Vc2 alternate is applied to the lamp DL. Further, since a high voltage pulse voltage of about 3 to 5 KV for dielectric breakdown of the lamp DL by the high voltage pulse generation circuit 2 is superimposed on this rectangular wave voltage, the voltage VDL applied to the lamp DL is as shown in FIG.

《Start-up mode》
When the lamp DL breaks down, the lamp DL shifts from glow discharge to arc discharge, and the lamp voltage VDL increases from about 0 V toward the rated voltage over several minutes. The Vla detection circuit 11 detects the lamp voltage VDL, selects the target power / current in the output characteristic table of FIG. 5 based on the voltage VDL, and outputs an on-width drive signal that can supply the target value. . By controlling based on the power characteristic curve of FIG. 5, excessive stress is not applied to the lamp DL. On the other hand, the ON width of the switching element Q2 is controlled by the error amplifier configuration so that the voltage Vc2 always becomes a predetermined value by the Vc detection circuit 12.

  The on-width control means for chopping differs between the switching elements Q1 and Q2 as described above, but the period T1 during which the switching element Q1 is chopped at a high frequency f1 of several tens to several hundreds of kilohertz (the switching element Q2 is kept off during this time). The operation in which the switching element Q2 is chopped at a high frequency f2 of several tens to several hundreds of kilohertz at a low frequency of several tens to several hundreds of hertz T2 (the switching element Q1 is kept off during this time) It is the same.

<Stable lighting mode>
In the third mode of FIG. 2, the lamp voltage is almost stable, and the lamp voltage is at the rated voltage. In this stable lighting mode, similarly to the start mode, the chopping of the switching element Q1 is controlled to supply the target power / current referred to in the power characteristic table of FIG. 5 based on the detected lamp voltage VDL. For example, when the lamp is stabilized at 90 V, control is performed so that 0.77 A and 70 W are supplied to the lamp from FIG. The example of FIG. 5 shows the characteristics of a discharge lamp lighting device to which a 70 W lamp having a general rated lamp voltage of 90 V is connected.

  In the chopping operation of the switching element Q2, similarly to the start mode, the ON width is controlled by the error amplifier configuration so that the voltage Vc2 of the capacitor C2 always becomes a predetermined value. The configuration for detecting the voltage Vc2 of the capacitor C2 and the configuration for detecting the lamp voltage are not particularly limited. In short, the frequency f1 of the switching element Q1 can be controlled so that appropriate lamp power is supplied according to the lamp voltage while controlling the frequency f2 of the switching element Q2 so that the voltage Vc2 of the capacitor C2 becomes a predetermined value. If it is good.

  FIG. 4 shows a chopping operation common to the start mode and the stable lighting mode. In both the start mode and the stable lighting mode, the current IDL flowing through the lamp and the power WDL (not shown: IDL × VDL) applied to the lamp are equal in both the period T1 and the period T2, and the lamp has less stress. Has been. In order to satisfy this, it is desirable to design the chopping frequency and the ON width of the switching element Q1 and the switching element Q2 in consideration of the following two points.

1) Ton1 / τ1≈Ton2 / τ2
That is, the control by the error amplifier of the switching element Q2 is designed so that the chopping operation of the switching element Q2 for keeping the target value Vc2 at a constant value converges to Ton1 / τ1.
2) Chopping period T1 of switching element Q1 = chopping period T2 of switching element Q2
Here, Ton1 and Ton2 are ON times when the switching elements Q1 and Q2 are chopped, respectively, and τ1 and τ2 are reciprocals of the chopping frequencies of the switching elements Q1 and Q2. That is, if Toff1 and Toff2 are the off times when the switching elements Q1 and Q2 are chopped, τ1 = Ton1 + Toff1 and τ2 = Ton2 + Toff2.

  According to the first embodiment, even when the capacity of the electrolytic capacitor C1 or C2 is different from the initial value due to the life or abnormality, the abnormality can be detected before starting the circuit. Even when an abnormality such as capacity loss occurs in the electrolytic capacitor while the lamp is lit, the distribution of the voltages generated in the upper and lower two electrolytic capacitors can be maintained at a desired voltage.

(Embodiment 2)
FIG. 6 is a circuit diagram of a high pressure discharge lamp lighting device according to Embodiment 2 of the present invention. The circuit configuration and the main part of the first embodiment shown in FIG. 1 are the same, except that electrolytic capacitors having different capacities are used as the electrolytic capacitors C1 and C2. Another difference is that a step-up chopper circuit that rectifies and smoothes the commercial AC power supply AC is used as the DC power supply Vs. The step-up chopper circuit includes a diode bridge DB, an inductor L4, a switching element Q4, and a diode D4, and outputs a DC voltage obtained by boosting the commercial AC power supply AC when the switching element Q4 is turned on / off at a high frequency. .

  Here, conditions necessary for lighting the high pressure discharge lamp will be described. In order to smoothly shift the high-pressure discharge lamp from glow discharge to arc discharge, a no-load voltage of 250 to 400 V is required, and this can be achieved with the circuit of Embodiment 1 (that is, with Vc1 = Vc2). As a DC power source Vs, it is necessary to supply a DC voltage of at least 500V.

  When the AC power source is converted into a DC voltage by the boost chopper circuit as in the second embodiment, it is necessary to boost the input voltage to at least the DC voltage of the input voltage × √2 × 1.1 in order to reduce the input current distortion. Here, 1.1 times means that 10% power fluctuation tolerance is provided. For example, 311V is required for a 200V AC power supply.

In the half-bridge inverter circuit, the voltages Vc1 and Vc2 of the capacitors C1 and C2 are alternately applied to the lamp DL. Therefore, the voltages Vc1 and Vc2 need to be at least the lamp stable lighting voltage (generally 70 to 120 V).
In order to satisfy the above conditions, the following design is possible.

a) The voltage required for smoothly shifting the high-pressure discharge lamp to arc discharge may be supplied only when chopping one of the switching elements Q1 or Q2 on one side. For example, the capacitor C1 may be designed to generate 300V.
b) The other electrolytic capacitor C2 needs to have a lamp stable lighting voltage or higher, for example, Vc2 = 150V.

  From the above, the output voltage of the step-up chopper circuit may output 450V. Since 450V ÷ √2 ÷ 1.1 = 290V, as a result, it is possible to realize a high-pressure discharge lamp lighting device that can support at least commercial power supply 100V / 242V in Japan and commercial power supply 120V / 277V in the United States.

Here, a design method capable of supplying desired symmetrical power to the lamp DL even when the capacities of the capacitors C1 and C2 are different will be described.
FIG. 7 is a diagram in which two step-down chopper circuits configured by the half-bridge inverter circuit of FIG. 6 are expanded into equivalent circuits. Each free wheel diode (diode for energizing regenerative current) is a built-in diode of the other switching element.

The step-down chopper circuit developed in two is a general one, and these two circuits have the following relationship.
VDL1 = Vc1 × Ton1 / τ1 = Vc1 × Ton1 × f1
VDL2 = Vc2 × Ton2 / τ2 = Vc2 × Ton2 × f2
VDL1 = VDL2

  As described in the first embodiment, as a lighting method with less stress on the lamp DL, the lamp voltages VDL1 and VDL2 become equal as a result of equalizing the vertical lamp current. Ton1 and Ton2 are the chopping ON times of the switching elements Q1 and Q2, respectively, τ1 and τ2 are the chopping periods of the switching elements Q1 and Q2, and f1 and f2 are the chopping frequencies of the switching elements Q1 and Q2.

  That is, in order for two step-down chopper circuits having different power supply voltages Vc1 and Vc2 to supply the constant voltage VDL to the lamp DL, the chopping frequencies f1 and f2 are Vc1 × Ton1 × f1 = Vc2 × Ton2 × f2. And the ON widths Ton1 and Ton2. FIG. 8 illustrates the above operation.

For example, when designing for the case of Vc1 = 300V and Vc2 = 150V,
VDL1 = 300V × Ton1 × f1
VDL2 = 150V × Ton2 × f2
∴300V × Ton1 × f1 = 150V × Ton2 × f2
Ton1 × f1 = Ton2 × f2 / 2

  For example, when Ton1 = Ton2, the frequency f1 for chopping the switching element Q1 is ½ times the frequency f2 for chopping the switching element Q2. However, as a premise of the period T1 for chopping the switching element Q1 and the period T2 for chopping the switching element Q2, the same power and current are supplied to the lamp DL to supplement the energy supplied from the capacitor C1 or C2. It is necessary to set T1 = period T2.

  Finally, no-load operation in this circuit system will be described with reference to FIG. When no load is applied, as shown in FIG. 9, the switching operation is started from the period T1 during which the higher voltage (Vc1 in the figure) of the electrolytic capacitor can be applied to the VDL, so that the start operation is efficiently performed. Further, since only the period T1 during which a high voltage can be applied to the VDL has a voltage necessary for smoothly shifting from the glow discharge to the arc discharge, the time distribution between the periods T1 and T2 is as shown in FIG. When T1> T2 is set and the voltage Vc1 of the electrolytic capacitor C1 decreases, the voltage Vc1 may be adjusted by executing the operation of the period T2, the capacitances of the electrolytic capacitors C1 and C2 are large, and the voltage Vc1 If there is almost no attenuation, T1 >> T2 may be set, or the period T2 may be eliminated.

  According to the second embodiment, even when the capacity of the electrolytic capacitor C1 or C2 is different from the initial value due to the life or abnormality, the abnormality can be detected before the inverter circuit is started. Even when an abnormality such as capacity loss occurs in the electrolytic capacitor while the lamp is lit, the distribution of the voltages generated in the upper and lower two electrolytic capacitors can be maintained at a desired voltage. Furthermore, the possibility of disappearing at the time of starting can be reduced, and dielectric breakdown can be efficiently caused.

(Embodiment 3)
FIG. 10 is a circuit diagram of a high pressure discharge lamp lighting device according to Embodiment 3 of the present invention. In the first and second embodiments described above, the half-bridge inverter is operated in a BCM (Boundary Current Mode) in which the current flowing through the inductor L1 is continuous and the chopper switching element is turned on when the current reaches 0A. ing. For this purpose, the circuits of FIGS. 1 and 6 are designed such that the current flowing through the inductor L1 is detected by the secondary winding, and the chopper switching element is turned on by the zero cross detection (ZCS detection). In this case, in order to operate the inverter efficiently, use a FET with a built-in fast recovery type diode (FRD) that can cut the regenerative current with a diode with a short reverse recovery time as a body diode, or an external FRD. Was considered desirable. However, when an FET with a built-in FRD is used to reduce the component mounting area, the built-in high-speed diode has a problem that the reverse recovery time changes greatly with respect to temperature rise, and the regenerative current also increases at high temperatures. .

A circuit that solves the above problem is realized as follows using a circuit having different capacities of the electrolytic capacitors C1 and C2 as shown in the second embodiment.
1) Regarding the setting of the capacitance of the electrolytic capacitor The capacitance is set such that n × C1 = C2 or C1 = n × C2 (n is a natural number). For example, C1 = 100 μF and C2 = 50 μF are set so that voltages applied to Vc1 = 150V and Vc2 = 300V, respectively.
2) Chopping of switching elements Q1 and Q2 While calculating Vc1 × Ton1 × f1 = Vc2 × Ton2 × f2 described in the second embodiment, the rated voltage 90V of a general low-power high-pressure discharge lamp is calculated as an example. ,
From VDL1 = Vc1 × Ton1 × f1, 90V = 150V × Ton1 × f1, so Ton1 × f1 = 0.6.
Further, from VDL2 = Vc2 × Ton2 × f2, 90V = 300V × Ton2 × f2, so Ton2 × f2 = 0.3.
For example, when Ton1 = Ton2, the switching frequency f1 of the switching element Q1 is set to be twice the switching frequency f2 of the switching element Q2.

  However, when the circuit of FIG. 1 or FIG. 6 operates and the component temperature rises, the reverse recovery time of the body diode built in the FET is gradually delayed, so the regenerative current increases and an ON signal enters the FET. From when the current actually flows from 0 A to a delay, and as a result, the peak value of the output current decreases. In particular, the switching operation of the switching element Q1 having a high switching frequency is affected by the fact that the reverse recovery time of the body diode of the FET is delayed by the temperature rise. That is, this is a mode in which a regenerative current flows through the body diode DQ2 of the switching element Q2 as a free wheel diode. As a result, there is a possibility that harmful effects such as the inability to output a predetermined output may occur.

  Therefore, in order to reduce the change due to the temperature characteristic of the body diode DQ2 of the switching element Q2 in particular, the free wheel diode of the switching element Q2 in which the regenerative current of the switching element Q1 with high dependence on the temperature characteristic flows depends on the temperature characteristic. An external FRD (fast recovery diode) with little change is inserted as a diode D2 in FIG. As a result, a highly efficient half-bridge inverter circuit can be realized. In addition, by inserting an external FRD (fast recovery diode), the FET (switching element Q2) that does not use the built-in body diode can be selected to select a FET with a lower on-resistance, thereby further improving circuit efficiency. A good circuit can be realized. The diode D1 is inserted in series with the switching element Q2 in order to block the current flowing through the body diode DQ2 of the switching element Q2.

  On the other hand, on the switching element Q2 side having a low switching frequency, even if the reverse recovery time is somewhat delayed, the rise of current at the time of switching is slow, so that it is not easily affected. That is, since the free wheel diode of the switching element Q1 through which the regenerative current of the switching element Q2 having a low dependence on the temperature characteristic flows can be an FET with a built-in FRD (fast recovery diode), the external FRD portion can be used. The number of parts can be reduced.

  According to the present embodiment, even when the number of components is small and the temperature of the components rises, it is possible to suppress a decrease in output due to an increase in the component temperature or a dull current response to a chopping signal, thereby maintaining a high circuit efficiency. Further, even when the capacity of the electrolytic capacitor C1 or C2 differs from the initial value due to the life or abnormality, it is possible to detect the abnormality before starting the circuit. Furthermore, even when an abnormality such as capacity loss occurs in the electrolytic capacitor while the lamp is lit, the distribution of the voltages generated in the upper and lower two electrolytic capacitors can be maintained at a desired voltage.

(Embodiment 4)
FIG. 11 shows a structural example of a lighting fixture using the discharge lamp lighting device of the present invention. (A), (b) is an example applied to a spotlight, (c) is an example applied to a downlight, in the figure, 5 is an electronic ballast storing the circuit of the lighting device, 6 is a high pressure discharge lamp The lamp body 7 is a wiring. A lighting system may be constructed by combining a plurality of these lighting fixtures. By realizing a small high-pressure discharge lamp lighting device using the above-described half-bridge inverter circuit system, it is possible to give design freedom to these high-pressure discharge lamp lighting fixtures.

It is a circuit diagram of Embodiment 1 of the present invention. It is operation | movement explanatory drawing which shows three processes from the non-lighting state of Embodiment 1 of this invention to the stable lighting state. It is a wave form diagram for description of operation at the time of no load of Embodiment 1 of this invention. It is a wave form diagram which shows the chopping operation common to the starting mode and stable lighting mode of Embodiment 1 of this invention. It is a characteristic view of the lighting device of Embodiment 1 of the present invention. It is a circuit diagram of Embodiment 2 of the present invention. FIG. 7 is a circuit diagram in which the step-down chopper circuit of the half-bridge inverter circuit of FIG. 6 is expanded into an equivalent circuit. It is operation | movement explanatory drawing at the time of lighting of Embodiment 2 of this invention. It is operation | movement explanatory drawing at the time of no load of Embodiment 2 of this invention. It is a circuit diagram of Embodiment 3 of the present invention. It is a perspective view which shows the lighting fixture of Embodiment 4 of this invention. It is a circuit diagram of the conventional high pressure discharge lamp lighting device. It is operation | movement explanatory drawing of the apparatus of FIG. It is operation | movement explanatory drawing of the apparatus of FIG. It is explanatory drawing for demonstrating the subject of the apparatus of FIG.

Explanation of symbols

Q1 1st switching element Q2 2nd switching element C1 1st capacitor C2 2nd capacitor C3 3rd capacitor L1 Inductor DL High pressure discharge lamp 11 Vla detection circuit (lamp voltage detection circuit)
12 Vc detection circuit (capacitor voltage detection circuit)

Claims (7)

An inverter circuit that obtains a rectangular wave AC output by alternating the DC output of the DC power supply, the inverter circuit comprising: a series circuit of first and second capacitors connected between output terminals of the DC power supply; A series circuit of first and second switching elements connected in parallel to the series circuit of the second capacitor; and a control circuit for controlling the switching of the first and second switching elements, the first and second Between the connection point of the capacitor and the connection point of the first and second switching elements, at least a series connection circuit of the high pressure discharge lamp and the inductor and a third capacitor connected in parallel to the high pressure discharge lamp are connected. A first period during which the first switching element on the high potential side of the DC power supply is turned on / off at the first frequency, and a second switching element on the low potential side of the DC power supply at the second frequency. In the lighting device for supplying desired power to the high pressure discharge lamp by alternately repeating the second period of turning on and off at a frequency lower than the first and second frequencies, the control circuit includes: A first detecting means for determining a control frequency of one of the switching elements and a voltage of at least one of the first and second capacitors to detect a control frequency of the other switching element. A high pressure discharge lamp lighting device comprising: a second detecting means for determining. 2. The high-pressure discharge lamp lighting device according to claim 1, wherein at least the first or second capacitor is turned on before turning on / off the first and second switching elements at the start of operation of the high-pressure discharge lamp lighting device in which direct-current output starts to be supplied from the direct-current power source. A high pressure discharge lamp lighting device characterized by detecting one of the voltages. 3. The high pressure discharge lamp lighting device according to claim 1, wherein the capacities of the first and second capacitors are set to different values. 4. The operation of the high pressure discharge lamp lighting device according to claim 3, wherein the DC power supply starts to be supplied from the DC power supply, and the switching element connected to the capacitor having the smaller capacity is turned on / off at the connection end with the DC power supply. A high pressure discharge lamp lighting device characterized by starting operation. 5. The period T1 during which the switching element connected to the capacitor having the smaller capacity is turned on and off at the time of no load before the high-pressure discharge lamp is turned on. A high pressure discharge lamp lighting device characterized in that a relationship of a period T2 during which the switching element connected to the capacitor having a larger capacitance is turned on and off is T1 >> T2. 6. The switching element according to claim 3, wherein the switching element connected to the capacitor having the smaller capacity at the connection end to the DC power supply is the first FET, and the capacitor having the larger capacity at the connection end to the DC power supply. The switching element connected to the first FET has a second FET, a first circuit having a cathode connected to the drain of the second FET, a parallel circuit to the series circuit, and the anode side is connected to the second diode. The regenerative diode built in the first FET has a shorter reverse recovery time than the regenerative diode built in the second FET, and the first and second regenerative diodes are connected to the source of the FET. A high pressure discharge lamp lighting device characterized in that the diode has a reverse recovery time equivalent to that of the regenerative diode built in the first FET. An illumination device comprising the high-pressure discharge lamp lighting device according to any one of claims 1 to 6.

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