JP4016345B2 - Discharge lamp lighting device - Google Patents

Description

  The present invention relates to a discharge lamp lighting device that lights a discharge lamp with a high-frequency current generated by a switching element.

  FIG. 34 is a circuit diagram of a conventional discharge lamp lighting device, in which IV is connected to a DC power source E, an inverter circuit for switching a DC current of the DC power source E to convert it into a high frequency current, and LAC1 an inverter circuit. A discharge lamp load circuit for lighting the discharge lamp LA by the high-frequency current generated by IV, NP1 is a protection circuit for detecting a malfunction of the discharge lamp load circuit LAC1 and outputting a control signal for stopping the operation of the inverter circuit IV.

Details of each circuit will be described below.
The inverter circuit IV is connected in series between both electrodes of the DC power supply E and a starting circuit in which a starting resistor R1 and a control power supply capacitor C1 are connected in series, and a constant voltage diode DZ1 is connected in parallel to the control power supply capacitor C1. Via a pair of MOS-FETs Q1, Q2 (hereinafter referred to as switching elements Q1, Q2), an inverter control circuit IC1 (hereinafter referred to as IV control circuit IC1) for controlling the switching elements Q1, Q2, and an IV control circuit IC1 The frequency control circuit FC1 for setting the switching frequency of the switching elements Q1 and Q2 is provided. Each terminal of the IV control circuit IC1 has a power supply terminal 1 (hereinafter referred to as a terminal 1) as a control power supply capacitor C1, an output terminal 2, 3, 4 (hereinafter referred to as terminals 2, 3, 4) are connected to switching elements Q1, Q2 and oscillation control terminal 6 , 7 (hereinafter referred to as terminals 6 and 7) are connected to the frequency control circuit FC1. The frequency control circuit FC1 includes a main oscillation resistor R2 and an oscillation capacitor C2 connected in parallel between the terminals 6 and 7 of the IV control circuit IC1 and the negative electrode of the DC power supply E. Thus, this oscillation When the IV control circuit IC1 oscillates at a frequency f = K * (current flowing out from the terminal 6 of the IV control circuit having a constant DC potential) with respect to a constant K determined by the capacitance of the capacitor C2, etc., the switching element Q1 , Q2 is configured to perform a switching operation at the frequency f.

Next, the discharge lamp load circuit LAC1 will be described.
As shown in FIG. 34, the discharge lamp load circuit LAC1 includes a ballast choke T1 at both ends of the switching element Q2, a discharge lamp LA having electrodes F1 and F2, and a coupling capacitor C4 connected in series. And a starting capacitor C3 connected in parallel.

  On the other hand, the protection circuit NP1 is a high-frequency voltage between the electrode F1 side terminal of the ballast choke T1 and the negative electrode of the DC power supply E by the detection capacitors C5 and C6 connected to the discharge lamp load circuit LAC1, the diodes D1 and D2, and the capacitor C7. The peak-to-peak voltage (Vmax−Vmin) of the waveform is detected, and when the DC voltage generated across the capacitor C7 exceeds the Zener voltage of the constant voltage diode DZ2, the IV control circuit IC1 connected to the protection circuit NP1 A signal is output to the oscillation stop terminal 5 (hereinafter referred to as terminal 5), and the switching operation of the switching elements Q1 and Q2 is stopped. When the discharge lamp LA is normally lit, the protection circuit NP1 does not operate because the DC voltage of the capacitor C7 is set to be lower than the Zener voltage of the constant voltage diode DZ2. The resistor R4 is for discharging the electric charge accumulated in the capacitor C7 when the power is turned off. The resistor R16 and the capacitor C11 adjust the voltage inputted to the terminal 5 by dividing it and smooth the external high frequency noise. This prevents the IV control circuit IC1 from malfunctioning.

Next, the operation of this conventional discharge lamp lighting device will be described.
When the discharge lamp lighting device is activated and current is supplied from the DC power source E to the inverter circuit IV, the control power capacitor C1 is charged by the activation current flowing from the DC power source E through the activation resistor R1, and the IV control circuit IC1 When the voltage at the terminal 1 reaches a specified operating voltage, the IV control circuit IC1 oscillates at a frequency f determined by the frequency control circuit FC1, and high-frequency signals are output from the terminals 2 and 4 to the switching elements Q1 and Q2. The switching elements Q1 and Q2 are alternately turned on and off to supply a high-frequency current to the discharge lamp load circuit LAC1, and a series circuit (coupling capacitor) composed of the ballast choke T1 and the starting capacitor C3 by the high-frequency current. Since the capacity of C4 is designed to be as large as several tens of times the capacity of the starting capacitor C3, the coupling capacitor C4 does not significantly affect the following resonance phenomenon) causes LC resonance, and the starting capacitor C3, that is, the discharge lamp A high voltage is generated at both ends of LA, the discharge lamp LA is started, and lighting is continued at the frequency f. Since the constant voltage diode DZ1 is connected in parallel to the control power supply capacitor C1, the voltage applied to the terminal 1 of the IV control circuit IC1 is limited by the Zener voltage of the constant voltage diode DZ1.

Next, the operation of the conventional protection circuit NP1 will be described.
When the discharge lamp LA is turned on, a high-frequency voltage in which a high-frequency voltage is superimposed on a constant DC voltage as shown in FIG. 35 is generated between the electrode F1 side terminal of the ballast choke T1 and the negative electrode of the DC power supply E. In the circuit NP1, the peak-to-peak voltage (Vmax-Vmin) is detected by the detection capacitors C5 and C6 and the diodes D1 and D2 connected therebetween, and further converted into a DC voltage by the capacitor C7 and input to the constant voltage diode DZ2. Is done. Here, when the discharge lamp LA is normally lit, since the DC voltage of the capacitor C7 is set to be equal to or lower than the Zener voltage of the constant voltage diode DZ2, an oscillation stop signal is output from the protection circuit NP1 to the IV control circuit IC1. It will never be done.

  However, for example, when the discharge lamp LA is rectified and lit at the end of its life, the high-frequency lamp voltage of the discharge lamp LA rises, so that the voltage of the capacitor C7 becomes higher than the Zener voltage of the constant voltage diode DZ2, and the protection circuit NP1 An oscillation stop signal is output to the terminal 5 of the IV control circuit IC1, and the switching operation of the switching elements Q1 and Q2 is also stopped by stopping the oscillation of the IV control circuit IC1. As a result, the switching elements Q1, Q2 are prevented from malfunctioning due to abnormal heat generation, or the discharge lamp LA is prevented from being destroyed due to abnormally high temperatures in the vicinity of the electrodes F1, F2 of the discharge lamp LA. The oscillation stop state of the IV control circuit IC1 is reset when the voltage of the control power supply capacitor C1 falls below the specified voltage, and oscillation starts again when the voltage of the control power supply capacitor C1 exceeds the specified voltage.

  A large current flows through the ballast choke T1 and the starting capacitor C3 even when a high voltage associated with resonance occurs in the starting capacitor C3. However, if the discharge lamp LA is not lit at the end of its life or defective, the starting capacitor C3 Since the voltage between the terminals of the capacitor C7 continues to be abnormally high, the DC voltage of the capacitor C7 becomes higher than the Zener voltage of the constant voltage diode DZ2, and, similarly to the above, an oscillation stop signal is output from the protection circuit NP1 to the terminal 5, The oscillation of the circuit IV can be stopped. As a result, it is possible to prevent an excessive current from continuously flowing through the ballast choke T1 and the starting capacitor C3 and thereby destroying the ballast choke T1 and the starting capacitor C3.

  Further, when the discharge lamp LA is removed during lighting, a resonance current flows through the series circuit of the ballast choke T1 and the detection capacitors C5 and C6, and accordingly, the DC voltage of the capacitor C7 is changed to the constant voltage diode DZ2. Therefore, the oscillation stop signal is output from the protection circuit NP1 to the terminal 5 and the oscillation of the inverter circuit IV is stopped. Thus, even when the discharge lamp LA is removed during lighting, the oscillation of the inverter circuit IV is stopped and no high frequency current is supplied to the discharge lamp load circuit LAC1, so that no high frequency voltage is generated at the socket terminal of the discharge lamp LA. This can prevent a ground fault when replacing the lamp.

  However, in the conventional discharge lamp lighting device shown in FIG. 34, the voltage difference between the maximum value and the minimum value of the high-frequency voltage waveform between the electrode F1 side terminal of the ballast choke T1 and the negative electrode of the DC power supply E is detected. The protection circuit NP1 is configured to stop the oscillation of the inverter circuit IV by utilizing the fact that the difference becomes higher when the discharge lamp LA is normally lit than when it is abnormal (rectified lighting, non-lighting, no load). The circuit constant design for determining the protection level is very difficult. That is, in order to increase the reliability of the protection circuit NP1, it is necessary to provide a sufficient margin so that the protection circuit NP1 does not output an oscillation stop signal when the discharge lamp LA is normally lit, while the protection circuit NP1 is protected when the discharge lamp LA is abnormal. Although it is necessary to set a sufficient margin for the circuit NP1 to reliably output the oscillation stop signal, as is apparent from the circuit diagram of FIG. 31, the voltage difference detected by the protection circuit NP1 is the discharge lamp LA. In other words, the voltage applied to both ends of the starting capacitor C3 is detected. In general, considering that the lamp voltage of the discharge lamp LA varies greatly depending on the variation between individuals and the environmental temperature, This conventional abnormality detection method of the protection circuit NP1 has a problem that the above two design margins cannot be increased. In particular, in a discharge lamp lighting device having a dimming function, when the lamp current of the discharge lamp LA is lowered and dimmed, the lamp voltage rises greatly, so that the design of the protection circuit NP1 is very difficult and realistic. However, there is a problem that the above-described protection circuit NP1 cannot be applied to a discharge lamp lighting device having a dimming function.

  The present invention has been made to solve the above-described problems of the conventional discharge lamp lighting device, and a first object of the present invention is to allow a large design margin of the protection circuit and to perform normal lighting. An object of the present invention is to obtain a discharge lamp lighting device in which the protection circuit is highly reliable and the protection circuit can be easily designed because the time and the abnormality can be reliably identified.

  Further, the second object of the present invention is to discharge lamp lighting that can detect abnormalities of various abnormalities of the discharge lamp lighting device, such as rectified lighting, non-lighting, and no load, and can reliably control the operation of the inverter circuit. The object is to obtain a device.

  A third object of the present invention is to ensure that the discharge lamp can be lighted even in a discharge lamp lighting device having a preheating function for the electrodes of the discharge lamp, and that the operation of the inverter circuit can be reliably controlled in the event of an abnormality. An object is to obtain a discharge lamp lighting device.

  Furthermore, a fourth object of the present invention is to reliably turn on the discharge lamp even when the operating point in the steady state of the discharge lamp approaches or passes the resonance frequency of the discharge lamp load circuit, and reliably in the event of an abnormality. An object is to obtain a discharge lamp lighting device capable of controlling the operation of an inverter circuit.

  A fifth object of the present invention is to provide a discharge lamp that can reliably control the operation of an inverter circuit in the event of an abnormality while the discharge lamp is reliably re-lit after the power is restored even in the event of an instantaneous power failure. The object is to obtain a lighting device.

  A sixth object of the present invention is to provide a large design margin for a protection circuit even in a discharge lamp lighting device having a dimming function for a discharge lamp, and reliably distinguish between normal lighting and abnormal lighting. An object of the present invention is to obtain a discharge lamp lighting device with high reliability of a protection circuit that can reliably light a discharge lamp and can reliably control the operation of an inverter circuit when an abnormality occurs.

  Furthermore, a seventh object of the present invention is to obtain a discharge lamp lighting device with low electrode loss consumed by the electrode of the discharge lamp and high energy efficiency.

A discharge lamp lighting device according to the present invention includes a DC power supply, a switching element that switches a DC current supplied from the DC power supply to generate a high-frequency current, a switching control circuit that controls switching of the switching element, A plurality of discharge lamp load circuits each having a choke coil, a discharge lamp, and a coupling capacitor, which are connected in parallel to the switching element and connected in series, and the voltage of each coupling capacitor of the plurality of discharge lamp load circuits A first voltage detecting unit that converts the maximum voltage into a first DC voltage; a second voltage that converts a minimum voltage into a second DC voltage among the voltages of the coupling capacitors of the plurality of discharge lamp load circuits; When the first DC voltage detected by the voltage detection unit and the first voltage detection unit exceeds a first reference voltage, A first comparator that outputs a first control signal, and a second comparator that outputs the second control signal when the second DC voltage detected by the second voltage detector falls below a second reference voltage. A protection circuit that outputs a signal that suppresses the high-frequency current to the switching element circuit when either the first or second control signal is output. The voltage detection unit 1 includes a voltage dividing resistor that divides the voltage of each coupling capacitor in a plurality of discharge lamp load circuits, a constant voltage diode connected to the voltage dividing resistor, the voltage dividing resistor, and each coupling. A reverse current blocking diode provided between the capacitors, and outputs a voltage divided by the voltage dividing resistor and the constant voltage diode to the first comparator unit, A voltage dividing unit that divides a predetermined voltage; a constant voltage diode connected to the voltage dividing resistor; a cathode of the constant voltage diode; and each coupling capacitor in a plurality of discharge lamp load circuits; A reverse current blocking diode provided between the discharge lamps, and when the minimum voltage among the voltages of the coupling capacitors is higher than the Zener voltage of the constant voltage diode, the voltage dividing resistor and the constant voltage diode The divided voltage is output to the second comparator unit, and when the minimum voltage among the voltages of the coupling capacitors is lower than the Zener voltage of the constant voltage diode, the voltage supplied from the predetermined voltage is The second capacitor is applied to the coupling capacitor having the minimum voltage through the reverse current blocking diode. It is configured not to be applied to the paralator unit .

  Since the present invention is configured as described above, the following effects can be obtained.

A DC power supply, a switching element that switches a DC current supplied from the DC power supply, generates a high-frequency current, a switching control circuit that controls switching of the switching element, and is connected in parallel to the switching element, A plurality of discharge lamp load circuits having a choke coil, a discharge lamp and a coupling capacitor connected in series, and a maximum voltage among the voltages of the coupling capacitors of the plurality of discharge lamp load circuits is set to the first DC voltage. A first voltage detecting unit for converting; a second voltage detecting unit for converting a minimum voltage to a second DC voltage among the voltages of the coupling capacitors of the plurality of discharge lamp load circuits; and the first voltage detecting unit. A first control signal that outputs the first control signal when the first DC voltage detected by the unit exceeds a first reference voltage. Separator unit, and has a second comparator unit for the second DC voltage and outputting the second control signal to be below the second reference voltage, which is detected by said second voltage detecting unit, wherein A protection circuit that outputs a signal that suppresses the high-frequency current to the switching element circuit when either the first control signal or the second control signal is output, and the first voltage detection unit includes a plurality of discharge circuits. A voltage dividing resistor for dividing the voltage of each coupling capacitor in the lamp load circuit, a constant voltage diode connected to the voltage dividing resistor, and a backflow prevention diode provided between the voltage dividing resistor and each coupling capacitor The voltage divided by the voltage dividing resistor and the constant voltage diode is output to the first comparator unit, and the second voltage detecting unit outputs a predetermined voltage. A voltage dividing resistor to be pressed, a constant voltage diode provided in the voltage dividing resistor, a cathode of the constant voltage diode, a coupling capacitor in a plurality of discharge lamp load circuits, and a backflow prevention diode provided between the discharge lamps, When the minimum voltage among the voltages of the respective coupling capacitors is higher than the Zener voltage of the constant voltage diode, the voltage divided by the voltage dividing resistor and the constant voltage diode is supplied to the second comparator unit. When the minimum voltage among the voltages of the coupling capacitors is lower than the Zener voltage of the constant voltage diode, the voltage supplied from the predetermined voltage has the minimum voltage via the backflow prevention diode. Applied to the coupling capacitor and not applied to the second comparator section. Order to have forms, among the plurality of discharge lamps, any of the discharge lamp there is an effect that it is possible to detect an abnormality at the time of an abnormal state.
In addition, the abnormality is not only the state of rectified lighting 1 in which the detection voltage is increased compared to the case where all the lights are normally lit, but also the abnormality of rectified lighting 2 and the heavenly lighting which is detected voltages lower than that in which all the lights are normally lit. There is an effect that it can be detected.
Furthermore, there is an effect that the number of parts can be reduced as compared with the case where the comparator unit and the voltage detection unit are individually provided for the increase of the discharge lamp load circuit.

Embodiment 1 FIG.
FIG. 1 is a circuit diagram showing the configuration of a discharge lamp lighting device according to the first embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same or equivalent part as the conventional discharge lamp lighting device demonstrated in FIG. 34, and description is abbreviate | omitted.
Compared with the conventional discharge lamp lighting device of FIG. 34, in the first embodiment of the present invention shown in FIG. 1, the configuration of the protection circuit and the detection target for abnormality detection are different. That is, in the first embodiment, the protection circuit NP2 detects the voltage across the coupling capacitor C4 to detect an abnormality in the discharge lamp load circuit LAC1, and outputs a control signal to the IV control circuit IC1. For this reason, the protection circuit NP2 includes a voltage detection unit VIN that detects a DC voltage across the coupling capacitor C4 and a comparator unit COMP that compares the DC voltage detected by the voltage detection unit VIN with a reference voltage. And a control signal output unit VOUT that generates and outputs a control signal based on a comparison result in the comparator unit COMP.

Hereinafter, the detailed configuration of each part constituting the protection circuit NP2 will be described.
First, the voltage detection unit VIN includes detection resistors R10 and R11 that divide the voltage across the coupling capacitor C4, and a capacitor C10 that removes a high-frequency ripple component of the divided voltage, and the detection voltage converted into direct current Is output to the comparator unit COMP. The comparator COMP includes two comparators IC2 and IC3, and a resistor R12 that determines a high threshold value among two reference voltages obtained by dividing the DC voltage of the control power supply capacitor C1 by resistors R12, R13, and R14. The voltage at the connection point of the resistor R13 is input to the non-inverting input terminal of the comparator IC2, the voltage at the connection point of the resistor R13 and the resistor R14 that determines the low threshold is input to the inverting input terminal of the comparator IC3, and the voltage detection unit By configuring the detection voltage from VIN to be input to the inverting input terminal of the comparator IC2 and the non-inverting input terminal of the comparator IC3, a window type comparator is configured. The output terminals of the comparators IC2 and IC3 are open collectors, both output terminals are connected to the base of the transistor Q3, and the collector terminal of the transistor Q3 is connected to the terminal 5 of the IV control circuit IC1, Furthermore, a parallel circuit of a capacitor C11 and a resistor R16 for voltage division and external high frequency noise removal is provided between the collector terminal and the negative electrode of the DC power supply E, and between the collector terminal and the positive electrode of the control power supply capacitor C1. A voltage dividing resistor R15 is connected to form a control signal output unit VOUT.
The diode D3 connected between the non-inverting input terminal of the comparator IC3 and the control power supply capacitor C1 is a protective diode that clips the voltage of the comparator IC3 to the Zener voltage of the constant voltage diode DZ1.

Next, the circuit operation of the first embodiment shown in FIG. 1 will be described with reference to FIGS. The circuit operation from when the discharge lamp lighting device is activated until the discharge lamp LA is lit is the same as that of the conventional device of FIG. 31 described above, and therefore the description thereof will be omitted. In particular, details of the operation of the protection circuit NP2 will be described below. Explained.
When the discharge lamp lighting device is activated and the IV control circuit IC1 oscillates at the frequency f, the switching elements Q1 and Q2 are alternately turned on and off at the same frequency, and the discharge lamp LA is lit. At this time, the terminal voltage of the switching element Q2, that is, the input voltage to the discharge lamp load circuit LAC1, has a peak value at the voltage of the DC power supply E (hereinafter, 440V as an example) as shown in FIG. It becomes a high frequency voltage having f. The high-frequency voltage in FIG. 2A is a high-frequency AC voltage AC having a peak value of 220 V (440 V / 2) and a frequency f shown in FIG. 2B, and 220 V (440 V / 2) shown in FIG. Can be expressed as a composite voltage of the direct current voltage DC. Here, considering the voltage generated at both ends of the coupling capacitor C4 (the negative electrode side of the DC power supply E and the discharge lamp LA side of the coupling capacitor C4), the capacity of the coupling capacitor C4 is designed to be sufficiently large. The high-frequency voltage component shown in FIG. 2B is canceled by charging / discharging in the coupling capacitor C4. As a result, the coupling capacitor C4 has a direct-current voltage component shown in FIG. A quasi-DC voltage on which a slight high-frequency voltage is superimposed is generated.

  Thus, the quasi-DC voltage is divided by the voltage detection unit VIN of the protection circuit NP2, the high frequency component is removed by the capacitor C10 and converted into a DC voltage, and then output to the comparator COMP. Then, this DC voltage is compared with two reference voltages by a window type comparator composed of a comparator IC2 and a comparator IC3. When the DC voltage is outside the range of the reference voltage, the transistor Q3 is turned off and the terminal of the IV control circuit IC1 5, the oscillation stop signal is input, the oscillation of the IV control circuit IC1 is stopped, and the switching operation of the switching elements Q1 and Q2 is stopped. In the following, the case where the control signal of the protection circuit NP2 is input to the oscillation stop signal input terminal 5 of the IV control circuit IC1 will be described. For example, these control signals are directly or via the frequency control circuit FC1. The high frequency output supplied to the discharge lamp LA may be reduced by inputting to the frequency control terminal 6 and controlling the switching frequency of the switching elements Q1 and Q2.

Hereinafter, the operation of the protection circuit NP2 corresponding to each load state of the discharge lamp LA will be sequentially described in detail. FIG. 3 is an equivalent circuit diagram of the discharge lamp load circuit LAC1 and the voltage detection unit VIN in the protection circuit NP2 at the time of all-light normal lighting based on the concept shown in FIG. And an example of impedance. In the figure, “A” and “B” respectively represent the potential on the positive side of the coupling capacitor C4 and the potential of the detection resistor R11 with respect to the negative potential “G” of the DC power supply E.
As shown in the equivalent circuit diagram of FIG. 3, in this case, since the discharge lamp LA is high-frequency lighting of 45 kHz, it can be regarded equivalently as a resistance. Here, a JIS standard FHF32 (Hf) lamp is assumed. 280Ω. Considering the voltage generated at both ends of the coupling capacitor C4 in this circuit, the total resistance value of the detection resistors R10 and R11 is about 1000 times as high as that of the discharge lamp LA. The power source DC is charged to approximately 220 V via the ballast choke T1 and the discharge lamp LA, and the same charge is alternately charged and discharged via the ballast choke T1, the discharge lamp LA, and the starting capacitor C3 by the high frequency power source AC. As a result, the potential “A” of the coupling capacitor C4 becomes a DC voltage of approximately 220 V on which some high frequency components are superimposed. Further, the potential “B” of the detection resistor R11 is about 7V by dividing the potential “A” by the detection resistor R10 (300 kΩ) and the detection resistor R11 (10 kΩ) and removing the high frequency component by the capacitor C10. DC voltage. As described in the conventional example, in general, the discharge lamp LA has a lamp voltage that changes due to a change in ambient temperature, aging, or variation between solids even if the lamp current is constant, that is, the equivalent resistance value changes greatly. As described above, according to the first embodiment, since the resistance values of the detection resistor R10 and the detection resistor R11 are high, for example, even if the equivalent resistance value of the discharge lamp changes by about 30% to 50%, There is a great advantage that the potentials “A” and “B” of the coupling capacitor C4 and the detection resistor R11 hardly change.

Next, regarding the operation in the rectifying lighting 1 (the state in which the electrode F1 is difficult to emit electrons at the end of life) and the rectifying lighting 2 (the state in which the electrodes F2 are difficult to emit electrons at the end of life) in the abnormal state of the discharge lamp LA. explain. FIG. 4 shows the high-frequency lamp current waveform of the discharge lamp LA in the case of all-light lighting, rectified lighting 1 and rectified lighting 2 (the coupling capacitor C4 is charged in the positive direction and the discharging direction is displayed in the negative). It can be seen that the symmetric waveform is obtained when all the lights are lit while the asymmetric waveform is obtained when rectified lighting 1 and rectified lighting 2 are used. FIG. 5 and FIG. 6 show changes in characteristics of the discharge lamp LA due to the difference in the lighting state on an equivalent circuit.
FIGS. 5 and 6 are equivalent circuit diagrams of the voltage detection unit VIN in the discharge lamp load circuit LAC1 and the protection circuit NP2 with respect to the rectified lighting 1 and the rectified lighting 2, respectively. ) (Several tens of ohms to several hundreds of ohms) and a diode series circuit and a large resistor (several hundreds of ohms to several KΩ) and an equivalent circuit composed of an anti-parallel circuit of a diode series circuit. . Here, when considering the potential of the coupling capacitor C4 during rectified lighting 1 and rectified lighting 2 with reference to FIGS. 5 and 6, the coupling capacitor C4 is connected to the DC power source DC in the same way as during normal lighting in FIG. By the ballast choke T1 and the discharge lamp LA (resistance (small) and diode in the rectified lighting 1 and resistance (large) and diode in the rectified lighting 2), it is about to be charged up to about 220V. Although the same charge is charged / discharged through the choke T1 and the starting capacitor C3, the charge current increases with respect to the discharge current in the rectified lighting 1 through the discharge lamp LA due to the change in the characteristics of the discharge lamp LA described above. On the contrary, in the rectified lighting 2, since the discharge current increases with respect to the charging current, the potentials “A” and “B” In the continuous lighting 1, a high value (“A” is 290 V and “B” is 9.4 V in the example of the equivalent circuit), and in the rectified lighting 2, a low value (“A” is in the example of the equivalent circuit). 150V, “B” changes to 4.8V).

Next, a description will be given of a case where the discharge lamp is not lit or unloaded during the abnormality of the discharge lamp LA. When the discharge lamp LA is not lit or unloaded, the equivalent resistance value of the discharge lamp LA becomes infinite, so the equivalent circuit is obtained by deleting the circuit of the discharge lamp LA as shown in FIG. In FIG. 7, when considering the potential of the coupling capacitor C4, there is no path for charging the coupling capacitor C4 from the DC power source DC, and from the high frequency power source AC to the coupling capacitor C4 via the ballast choke T1 and the starting capacitor C3. Since the same charge is alternately charged and discharged, the potentials “A” and “B” are both 0V.
As described above, the potential “A” of the coupling capacitor C4 and the potential “B” of the detection resistor R11 corresponding to each load state of the discharge lamp in the first embodiment are summarized as shown in FIG.

  In this way, the resistor R12 is preliminarily set so that the reference voltage on the high threshold side of the comparator part COMP constituted by the comparators IC2 and IC3 in FIG. 1 is, for example, 8V and the reference voltage on the low threshold side is 6V. , R13 and R14 can be designed by inputting the DC potential “B” of FIG. 8 to the comparator unit, so that the outputs of the comparators IC2 and IC3 are both HI when all the lights are normally lit. Since the transistor Q3 of the part VOUT is in the ON state, the oscillation stop signal is not output to the terminal 5 of the IV control circuit IC1, and the normal all-lighting can be continued. On the other hand, in the rectified lighting 1, the output of the comparator IC2 is In the case of rectified lighting 2, non-lighting and no load, the output of the comparator IC3 becomes LO and the transistor Q3 is turned off, so that the IV control circuit IC1 An oscillation stop signal is output to the terminal 5 to stop the oscillation of the inverter circuit IV, and when the rectified light is turned on or not lighted, the excessive current to the ballast choke T1 and the starting capacitor C3 is cut off to prevent the circuit from being destroyed. When there is no load, the high-frequency voltage generated at the socket of the discharge lamp LA can be turned off.

As described above, according to the first embodiment, at the time of normal lighting, the lamp voltage is hardly influenced by the variation among the individual discharge lamps LA and the environmental temperature, and at the time of abnormality, as shown in FIG. Further, paying attention to the voltage at both ends of the coupling capacitor C4 whose potential changes greatly corresponding to each load state of the discharge lamp, the voltage at both ends of the coupling capacitor C4 is detected to detect the abnormality of the discharge lamp load circuit LC1. Since it is configured to detect, a sufficient margin for not operating the protection circuit when the discharge lamp LA is normally lit can be secured, and when the discharge lamp LA is abnormal, the protection circuit operates reliably to stop the oscillation of the inverter circuit IV. Therefore, a reliable discharge lamp lighting device can be obtained. Continuation of the lighting failure of the discharge lamp lighting device caused by the lamp unlit and destruction of the discharge lamp LA, or the effect of preventing the ground fault or the like during lamp replacement.
In addition, since a sufficient margin can be secured for the operation of the protection circuit NP2 as described above, there is an effect that the design of the protection circuit NP2 such as setting of a reference voltage becomes easy.

  Further, in the first embodiment, the protection circuit NP2 is configured by the voltage detection unit VIN, the comparator unit COMP, and the control signal output unit VOUT, and the comparator unit COMP is configured by a window type comparator having two reference voltages. The effect of being able to detect both the rectified lighting 1 state in which the detection voltage increases compared to when all light is normally lit and the abnormality in both rectified lighting 2 and non-lighting where the detection voltage is lower than when all light is normally lit. is there.

1 shows an example in which only one discharge lamp LA is connected. However, even when a plurality of discharge lamps are connected in series, when one of them becomes an abnormal state, Since the protection circuit NP2 detects an abnormality by the same circuit operation as described above and outputs an oscillation stop signal to the IV control circuit IC1, the same effect can be obtained.
Furthermore, in FIG. 1, the case where the resistors R12, R13, and R14 that set the reference voltage of the comparator unit are configured by fixed resistors has been described. However, some of these resistors are configured by variable resistors, and the reference voltage is set. If, for example, the discharge lamp has different rated values, the reference value can be set more precisely according to the characteristics of the discharge lamp LA.

Embodiment 2. FIG.
FIG. 9 is a circuit diagram of a discharge lamp lighting device showing Embodiment 2 of the present invention. In Embodiment 2, the configuration of the voltage detection unit VIN of the protection circuit is different from that of Embodiment 1 described above. Only is different. That is, in the first embodiment, the voltage detection unit VIN is configured by the detection resistors R10 and R11, whereas in the protection circuit NP3 of the second embodiment, the detection resistors R20 and R21 and the constant voltage diode DZ4 are divided. It has a pressed configuration. The resistor R22 connected in parallel with the constant voltage diode DZ4 is several times higher than the detection resistors R20 and R21, and discharges the charge of the coupling capacitor C4 after the inverter circuit IV stops oscillating. Therefore, even without this resistor R22, there is no problem in the operation of the protection circuit NP3. Also, the same or corresponding parts as those in the first embodiment shown in FIG.

FIGS. 10 to 13 show the all-lamp normal lighting (FIG. 10), the rectified lighting 1 (the electrode F1 is at the end of its life) (FIG. 11), and the rectified lighting 2 (the electrode F2). FIG. 12 shows an example of an equivalent circuit diagram of the voltage detector VIN of the discharge lamp load circuit LAC1 and the protection circuit NP3 in each load state of end of life) (FIG. 12) and non-lighting and no load (FIG. 13). In the figure, the potentials “A” and “B” represent the potential of the coupling capacitor C4 and the potential of the detection resistor R21, respectively, as in FIG.
Thus, as in the first embodiment, the DC potentials “A” and “B” in each load state of the discharge lamp LA are calculated from these equivalent circuit diagrams as shown in FIG. For comparison, FIG. 14 also shows the potential in the first embodiment and the potential in the case where the dimming operation described in the fourth embodiment is performed.

  As is apparent from FIG. 14, the potential “A” of the coupling capacitor C4 has the same value in the first embodiment and the second embodiment, but the potential “B” is the same as that of the constant voltage diode DZ4. According to the threshold characteristics, the change in the second embodiment is more clear in the normal lighting and in the abnormal time (rectified lighting 1, rectified lighting 2, non-lighting and no load) compared to the first embodiment. I understand that. Therefore, according to the second embodiment, the voltage on the high threshold side of the window comparator constituted by the comparators IC2, IC3, etc. is set to 10 V, for example, and the voltage on the low threshold side is set to 4 V, for example. Since the difference between the threshold value of the potential “B” at the normal time and the abnormal time can be set larger than in the first embodiment, the reliability of the protection circuit is further improved. Note that such an operation can be made to function more effectively by setting the voltage of the constant voltage diode DZ4 of the protection circuit NP3 in the vicinity of the voltage generated in the coupling capacitor C4 during normal lighting.

  As described above, in the second embodiment, since the voltage detection unit VIN of the protection circuit NP3 is configured by the detection resistors R20 and R21 and the constant voltage diode DZ4, the change in the potential “B” can be increased. Even if there is a variation in the characteristic value and the lamp characteristic, the protection circuit NP3 can continue the oscillation of the inverter circuit IV (without stopping) when it is normally lit, and can reliably stop the oscillation of the inverter circuit IV when it is abnormal. In comparison with the first embodiment, there is an effect that the reliability is further improved.

  In the second embodiment (FIG. 9), the example in which the coupling capacitor C4 is disposed on the negative electrode side of the switching element Q2 is shown. However, the voltage at both ends may be detected by disposing the coupling capacitor C4 on the positive electrode side. . FIG. 9 shows an example in which the voltage between both ends of the coupling capacitor C4 (the negative side of the DC power supply E and the discharge lamp LA side of the coupling capacitor C4) is used as the voltage input to the protection circuit NP3. For example, a voltage between the positive electrode side of the DC power supply E and the discharge lamp LA side of the coupling capacitor C4 may be detected. In this case, the detected voltage is a combined voltage of the DC power supply E and the coupling capacitor C4. Since the voltage of the coupling capacitor C4 can be easily detected from this combined voltage, the quasi-DC voltage at both ends of the coupling capacitor C4 is substantially detected. The same effect as 2 can be obtained. Further, the coupling capacitor C4 is constituted by a plurality of coupling capacitors, and the voltage of any one of these capacitors is detected, or a detection capacitor is separately provided in addition to the coupling capacitor C4. As a method for detecting the quasi-DC voltage generated in the coupling capacitor C4 while maintaining the essential configuration of the second embodiment, various modifications are possible.

Embodiment 3 FIG.
FIG. 15 shows a circuit diagram of a discharge lamp lighting device according to Embodiment 3 of the present invention as one of modifications. In the third embodiment, the discharge lamp load circuit LAC1 is connected to both ends of the switching element Q2 of the inverter circuit IV in the second embodiment (FIG. 9), whereas the discharge lamp load circuit LAC4 is connected to the switching element Q1. The voltage detected by the protection circuit NP3 is the voltage between the negative electrode side of the DC power supply E and the discharge lamp LA side of the coupling capacitor C4. In this case, the detected voltage is a voltage obtained by subtracting the voltage at both ends of the coupling capacitor C4 from the voltage of the DC power supply E. Even if such a voltage value is used, protection is performed in the same manner as in the second embodiment. A circuit can be configured, and the same effect can be obtained even if the connection position of the coupling capacitor C4 and the position of the voltage to be detected are variously changed.

Embodiment 4 FIG.
In FIG. 16, the circuit diagram of the discharge lamp lighting device which is Embodiment 4 of this invention is shown. In the fourth embodiment, the function of continuously dimming the discharge lamp LA is added to the second embodiment described above. Therefore, the main oscillation of the frequency control circuit FC2 that determines the oscillation frequency of the IV control circuit IC1. The resistor R99 is composed of a variable resistor. In FIG. 16, the same or corresponding parts as in FIG.

  Hereinafter, the operation of the fourth embodiment will be described. In FIG. 16, when the IV control circuit IC1 is oscillating, the terminal 6 of the IV control circuit IC1 is a constant DC voltage, and the greater the current flowing from this terminal 6 to the negative electrode of the DC power supply E, the higher the oscillation frequency. It has the characteristic which becomes. Accordingly, when the variable resistor R99 is gradually reduced from the state in which the discharge lamp LA is all lighted, the current flowing out from the terminal 6 to the negative electrode of the DC power source E increases, and as a result, the oscillation frequency of the IV control circuit IC1 gradually increases. And the impedance of the ballast choke T1 increases, so that the current of the discharge lamp LA is reduced and dimmed. FIG. 17 shows an example of an equivalent practical circuit of the voltage detector VIN of the discharge lamp load circuit LAC1 and the protection circuit NP3 during normal lighting dimming. As shown in the equivalent circuit diagram of FIG. 17, in this case, as the switching frequency is increased to 70 kHz by the dimming operation, the equivalent resistance value of the discharge lamp LA is 7.5 kΩ, which is 27 times that in the normal lighting condition. However, since the resistance values of the detection resistors R20 and R21 are sufficiently large with respect to the resistance of 7.5 kΩ, as shown in FIG. The potentials “A” and “B” of C4 and the detection resistor R11 hardly change to 218V and 7V with respect to 220V and 7V at the time of all-light normal lighting, and are almost the same voltages as at the time of all-light normal lighting. It becomes.

  As described above, if the discharge lamp LA is normally lit, the potential “B” to be detected even if the equivalent resistance value of the discharge lamp LA changes from several hundred Ω to several KΩ or several tens KΩ by the dimming operation. ”Hardly changes, so that the protection circuit NP3 can be applied to a discharge lamp lighting device having a dimming function in exactly the same manner, and the potential“ B ”of the discharge lamp LA is normal and abnormal. Since the change is large, there is an effect that a highly reliable protection circuit and discharge lamp lighting device can be obtained in exactly the same manner as in the first and second embodiments. Furthermore, since the circuit constant of the protection circuit NP3 can be made the same regardless of the type of the discharge lamp LA and the presence or absence of the dimming function, there is an advantage that parts can be standardized in various discharge lamp lighting devices.

  FIG. 18 shows an equivalent circuit diagram in the case where the resistor R2 is replaced with a variable resistor and the dimming operation is performed in the first embodiment. In this case as well, “A” and “B” As shown in FIG. 14, the potentials of “215 V and 7 V are almost the same as those of 220 V and 7 V when all light is normally turned on, and the same effect as in the fourth embodiment can be obtained. .

Embodiment 5 FIG.
FIG. 19 shows a circuit diagram of a discharge lamp lighting device according to Embodiment 5 of the present invention. In the fifth embodiment, as the discharge lamp load circuit LAC3, in addition to the discharge lamp load circuit comprising the discharge lamp LA (starting capacitor C3 in parallel), the coupling capacitor C4, and the ballast choke T1 of the second embodiment, A discharge lamp load circuit comprising a lamp LAY (a start capacitor C3Y in parallel), a coupling capacitor C4Y, and a ballast choke T1Y is connected in parallel, and accordingly, two sets of voltage detectors VIN are connected to the protection circuit NP4. (Detection resistor R21, constant voltage diode DZ4, detection resistor R21), VIN2 (detection resistor R21Y, constant voltage diode DZ4Y, detection resistor R21Y) and comparator unit COMP (comparators IC2, IC3 and reference resistors R12, R13, R14), COMP2 (Comparator IC2Y, I 3Y and reference resistors R12Y, R13Y, R14Y), and outputs from these two comparator units are input and aggregated into a single control signal output unit VOUT, and one control signal is output from the control signal output unit VOUT. The signal is output to the terminal 5 of the IV control circuit IC1. In addition, the same code | symbol is attached | subjected to the same or equivalent part as the said Embodiment 2, and description is abbreviate | omitted.

  Hereinafter, the operation of the fifth embodiment will be described. In FIG. 19, when both the discharge lamps LA and LAY are normal, the outputs of the comparators IC2, IC3, IC2Y, IC3Y are all HI as in the second embodiment, and therefore the transistor Q3 is on, so that the protection circuit NP4 is turned on. No discharge stop signal is output from the discharge lamps LA and LAY, and the normal lighting continues. On the other hand, when one of the discharge lamps LA and LAY is in an abnormal state, the detection voltages output from the voltage detection units connected to the respective discharge lamp load circuits are the comparators IC2 and IC3, or IC2Y and Since any of these outputs becomes L0 compared with the reference voltage by IC3Y, transistor Q3 is turned off, and an oscillation stop signal is output from protection circuit NP4 to IV control circuit IC1 to stop oscillation of inverter circuit IV. To do.

  As described above, according to the fifth embodiment, since the voltage detectors VIN and VIN2 are connected to each of the plurality of discharge lamp load circuits, when any of the discharge lamps becomes abnormal, the inverter circuit IV Oscillation can be stopped, and the protection circuit can be applied to the two-lamp parallel lighting circuit of the discharge lamps LA and LAY.

  Further, since the comparator units COMP and COMP2 are connected to the voltage detection units VIN and VIN2, respectively, the reference voltages of the comparator units COMP and COMP2 can be set according to the characteristics of each discharge lamp load circuit, and fine setting is possible. There is an effect.

Further, a single control signal output unit VOUT is provided for the plurality of voltage detection units VIN and VIN2 and the comparator units COMP and COMP2, and outputs from the plurality of comparator units COMP and COMP2 are aggregated to output a control signal. Since it is configured, the number of control signal output units VOUT can be reduced.
In FIG. 19, the case where there are two discharge lamp load circuits is illustrated, but it is needless to say that the present invention can be similarly applied to three or more parallel lighting circuits.

Embodiment 6 FIG.
FIG. 20 shows a circuit diagram of a discharge lamp lighting device according to Embodiment 6 of the present invention. In the sixth embodiment, the circuit of the second embodiment is provided with a mask circuit MSK that masks the function of the protection circuit for a certain time after the discharge lamp lighting device is turned on. The above protection circuit can also be applied to a discharge lamp lighting device that lights the discharge lamp LA after preheating the electrodes of the discharge lamp LA. In the following description, the mask circuit MSK and the frequency control circuit FC3, which are characteristic components of the sixth embodiment, will be mainly described, and the same reference numerals are used for the same or corresponding parts as in the second embodiment (FIG. 9). The description is omitted.

  As shown in FIG. 20, in the sixth embodiment, the frequency control circuit FC3 includes a preheating oscillation resistor R3 between the terminal 6 of the IV control circuit IC1 and the negative electrode of the DC power supply E in addition to the main oscillation resistor R2 and the oscillation capacitor C2. And a series circuit composed of the preheating oscillation capacitor 30. The protection circuit NP5 includes a mask circuit MSK having a timer circuit TM including resistors R18 and R19, a capacitor C12, and a constant voltage diode DZ3. The mask circuit MSK is connected to the oscillation stop terminal 5 of the IV control circuit IC1. The transistor Q4 is connected between the negative electrodes of the DC power supply E, and the output terminal of the transistor Q5 driven by the output of the timer circuit TM is connected to the input terminal of the transistor Q4. Thus, when the discharge lamp lighting device is turned on, the capacitor C12 is charged via the resistor R1 and the resistor R18, and the transistor Q5 is turned on when the voltage of the capacitor C12 exceeds the Zener voltage of the constant voltage diode DZ3 after a certain time. The transistor Q4 is configured to be turned off. In order to drive the timer circuit TM, the positive side of the resistor 18 is connected to the control power supply capacitor C1, and in order to drive the transistor Q4, the resistor R17 is connected between the control power supply capacitor C1 and the base of the transistor Q4. Yes.

  Next, operations of the mask circuit MSK and the frequency control circuit FC3 in the sixth embodiment will be described with reference to FIGS. Here, FIG. 21 is an LC series resonance curve diagram of the ballast choke T1 and the starting capacitor C3 in the discharge lamp load circuit LAC1, in which (1) is a resonance curve when the discharge lamp LA is lit, and (2) is a discharge lamp. It is a resonance curve at the time of LA non-lighting. FIGS. 22 and 23 show the change over time in the voltage between both electrodes of the discharge lamp LA and the transistor after the DC power source E is turned on when the discharge lamp LA is normally lit and when not lit. The operation of Q3 and transistor Q4 is shown.

  First, in FIG. 20, when the inverter circuit IV is connected to the DC power supply E and the charging voltage of the control power supply capacitor C1 reaches the oscillation start voltage of the IV control circuit IC1, the IV control circuit IC1 starts to oscillate. At this time, the terminal 6 of the IV control circuit IC1 is a constant DC voltage, and current flows out from the terminal 6 via the main oscillation resistor R2 and the preheating oscillation resistor R3. The current of the preheating oscillation resistor R3 is The preheating oscillation capacitor C30 is being charged and decreases with time. For example, it becomes zero in about 3 seconds. Incidentally, since the IV control circuit IC1 has a characteristic that the oscillation frequency is higher as the current flowing out from the terminal 6 is larger, the IV control circuit IC1 is initially higher as the current flowing out from the terminal 6 is reduced. Oscillation is started at a frequency, and the oscillation frequency is controlled to gradually decrease to a predetermined frequency.

  The change in the oscillation frequency of the IV control circuit IC1 during this period and the change in the resonance voltage between the two poles of the discharge lamp LA associated therewith will be described with reference to FIGS. The oscillation frequency when the IV control circuit IC1 first oscillates after the DC power supply E is turned on is designed to be controlled in a frequency range higher than the resonance frequency f0 of the ballast choke T1 and the starting capacitor C3. When the power supply E is turned on, the discharge lamp lighting device starts oscillation at the frequency fH and the operating point H2 at time t0. On the other hand, since the voltage between both electrodes of the discharge lamp LA at this time is designed to be a voltage VH2 lower than the starting voltage VS2 of the discharge lamp LA, the discharge lamp LA does not light up, and the electrode of the discharge lamp LA The electrodes F1 and F2 are preheated by the resonance current flowing through F1 and F2.

  Then, when the oscillation frequency of the IV control circuit IC1, that is, the switching frequency of the switching elements Q1 and Q2, gradually decreases, the voltage between both electrodes of the discharge lamp LA gradually increases along the resonance curve at the time of non-lighting, and the time t1 When the voltage across the discharge lamp LA reaches VS2 at the operating point S2 at the frequency fS, the discharge lamp LA is started (thus, the preheating time is from time t0 to t1). When the discharge lamp LA is lit, the impedance of the discharge lamp changes, and simultaneously with the lighting, the operating point moves from S2 to S1 on the resonance curve at the time of lighting, and the voltage between both electrodes of the discharge lamp LA decreases to VS1. Thereafter, the frequency decreases to fL which is a steady state in response to the decrease in the oscillation frequency of the IV control circuit IC1, and the discharge lamp LA continues to be lit at a predetermined lamp current determined by the impedance of the ballast choke T1. .

  On the other hand, as shown in FIG. 22, the entire operation of the protection circuit NP5 during this period is not lit as described in the second embodiment from the on time t0 of the DC power supply E to the lighting time t1 of the discharge lamp LA. Since the transistor Q3 is turned off to correspond to the state, the potential of the terminal 5 is low because the transistor Q5 is turned off and the transistor Q4 is turned on until the capacitor C12 of the timer circuit TM is charged to a predetermined voltage. Kept at potential. Thus, when the mask circuit MSK is not provided, the transistor Q3 is turned off during the preheating time, and therefore the oscillation stop signal is output from the protection circuit NP5 to the IV control circuit IC1 and the discharge lamp LA cannot be lit. According to the sixth embodiment, since the potential of the terminal 5 is kept low during the preheating time by the mask circuit MSK, the oscillation stop signal is not output from the protection circuit NP5 to the terminal 5 of the IV control circuit IC1, and the time At t1, the discharge lamp LA is lit without trouble.

  When the voltage of the capacitor C12 charged with the closed loop current of the control power supply capacitor C1 → resistor 18 → capacitor C12 → control power supply capacitor C1 reaches the Zener voltage of the constant voltage diode DZ3 at time t3, the transistor Q5 is turned on, and the transistor Q4 Is turned off (thus, the time from t0 to t3 is the masking time of the protection circuit NP5 by the mask circuit MSK and is set longer than the preheating time), but the discharge lamp LA is already lit at time t3. Since this corresponds to the all-light normal lighting state described in the second embodiment, the transistor Q3 is turned on, the transmission stop signal is not output from the protection circuit NP5, and the lighting state is continued.

  On the other hand, when the discharge lamp LA is not lit due to the end of its life or failure, the operating point in FIG. 21 increases as the oscillation frequency of the IV control circuit IC1 decreases from the initial oscillation frequency to the steady state frequency, fH → fS → fL. As shown in FIG. 23, the voltage between both electrodes of the discharge lamp LA rises from VH2 to VL2 between time t0 and time t2, and becomes constant thereafter. During this time, the state of the discharge lamp load circuit LAC1 corresponds to the non-lighting state described in the second embodiment. Therefore, the transistor Q3 of the protection circuit NP5 is turned off. Since the transistor Q3 is off, the transistor Q4 is turned off at the time t3 when the masking time of the mask circuit MSK ends, and at the same time, an oscillation stop signal is output from the protection circuit NP5 to the terminal 5 of the IV control circuit IC1, and the inverter circuit IV Oscillation is stopped and the excessive resonance current continues to flow through the ballast choke T1 and the starting capacitor C3.

As described above, in the sixth embodiment, since the protection circuit NP5 is added with the mask circuit for masking the output of the oscillation stop signal for a predetermined time after the DC power source E is turned on, the discharge lamp is preheated after the electrodes F1 and F2 are preheated. The present invention can also be applied to a discharge lamp lighting device having a function of lighting LA, and there is an effect that a normal discharge lamp can be reliably lit and a discharge lamp lighting device capable of reliably stopping oscillation in the event of an abnormality is obtained.
The mask time is set by the timer circuit as described above. For example, the lighting of the discharge lamp LA is detected in the output state of the comparators IC2 and IC3, and the mask function is canceled in synchronization with the detection result. But you can.

Embodiment 7 FIG.
FIG. 24 shows a circuit diagram of a discharge lamp lighting device according to Embodiment 7 of the present invention. In the seventh embodiment, an over-resonance detection circuit AP that detects an abnormality by detecting a high-frequency current flowing through the discharge lamp load circuit LAC1 is provided in the above-described sixth embodiment. Even in a discharge lamp lighting device whose control range passes the resonance frequency f0 of the ballast choke T1 and the starting capacitor C3 or is configured to approach the resonance frequency f0, the lamp can be lit reliably and an abnormality can be detected more precisely. It is configured to be able to do so. In addition, the same code | symbol is attached | subjected to the same or equivalent part as the said Embodiment 6 (FIG. 20), and description is abbreviate | omitted.

  As shown in FIG. 24, in the seventh embodiment, an overresonance detection circuit AP is added between the terminal 5 of the IV control circuit IC1 and the negative electrode of the DC power supply E. The over-resonance detection circuit AP includes a detection resistor R5 of about 1Ω connected between the coupling capacitor C4 and the negative electrode of the DC power supply E, a connection between the detection resistor R5 and the coupling capacitor C4, and a terminal of the IV control circuit IC1. 5, a series circuit including a constant voltage diode DZ5, a resistor 26, and a diode D5 connected to each other. In the protection circuit NP6, a diode D6 for separating the protection circuit NP6 and the overresonance detection circuit AP is connected between the terminal 5 of the IV control circuit IC1 and the collector of the transistor Q3.

  Hereinafter, the operation of the protection circuit NP6 and the overresonance detection circuit AP will be described with reference to FIG. 24 and FIG. 25 showing the LC series resonance curve of the seventh embodiment. 24 and 25, when the inverter circuit IV is connected to the DC power supply E and the charging voltage of the control power supply capacitor C1 reaches the oscillation start voltage of the IV control circuit IC1, the IV control circuit is the same as in the sixth embodiment. IC1 starts oscillating at frequency fH and operating point H2. Then, when the frequency gradually decreases as the outflow current from the terminal 6 decreases, the voltage between the two electrodes of the discharge lamp LA rises along the LC series resonance curve when the discharge lamp is not lit. The electrodes F1 and F2 are preheated, reach the starting voltage at the frequency fS, and the discharge lamp LA starts. At the same time, the operating point moves from S2 to S1 on the resonance curve during lighting. Thereafter, the frequency further passes through the resonance frequency f0 and gradually decreases to the operating point fL. At the operating point L1, the discharge lamp LA continues to be lit with a predetermined lamp current determined by the impedance of the ballast choke T1. To do. In the above operation, also in the seventh embodiment, since the protection circuit NP6 includes the mask circuit as in the sixth embodiment, the oscillation stop signal is not output until the discharge lamp LA is turned on.

  In the above description, the case where the discharge lamp is turned on has been described. In this way, the control range of the oscillation frequency of the inverter circuit IV passes through the resonance frequency f0 of the ballast choke T1 and the starting capacitor C3, or approaches the resonance frequency f0. In the discharge lamp lighting device configured to do so, for example, when the discharge lamp LA is not lit at the end of its life or defective, the operating point rises along the resonance curve at the time of non-lighting, and near the resonance frequency f0. However, the resonance voltage and the resonance current between the electrodes F1 and F2 of the discharge lamp LA are excessive, and the components of the discharge lamp LA and the discharge lamp load circuit are broken.

  Therefore, how the over-resonance detection circuit AP introduced in the seventh embodiment solves this problem will be described below with reference to FIGS. 25 and 26. In FIG. 25, when the oscillation frequency of the IV control circuit IC1 decreases from fH to fS (the operating point moves from H2 to S2), the resonance current flowing through the detection resistor R5 of the overresonance detection circuit AP increases and is detected accordingly. The positive peak value VP of the high-frequency voltage waveform at both ends of the resistor R5 increases as shown in FIG. If the discharge lamp LA does not light up while the frequency further decreases from fS to f0, when the maximum voltage VP2 set for circuit protection is reached (operation point P2, frequency fp). Since the positive voltage peak value VP of the detection resistor R5 exceeds the Zener voltage of the constant voltage diode DZ5, an oscillation stop signal is output to the terminal 5 of the IV control circuit IC1, and the oscillation of the inverter circuit IV is stopped.

  As described above, in the seventh embodiment, separately from the protection circuit NP6, a high-frequency current that flows through the discharge lamp load circuit LAC1 is detected, and an oscillation stop signal is output to the IV control circuit IC1 when an abnormality occurs. Since the circuit AP is added, the above-described protection circuit can be applied even to a discharge lamp lighting device in which the oscillation frequency of the inverter circuit IV approaches the resonance frequency f0. Exactly the same effect can be obtained.

  In the above description, the operation of the overresonance detection circuit AP has been described as means for avoiding an overresonance state that occurs in a discharge lamp lighting device in which the oscillation frequency of the inverter circuit IV approaches the resonance frequency f0. It is also possible to add this over-resonance detection circuit AP to all the embodiments of the present invention and to detect an abnormality of the discharge lamp LA in cooperation with the protection circuit. In this case, the over-resonance detection circuit AP is generated in the coupling capacitor C4. In addition to the voltage, the high-frequency current waveform supplied from the switching element is also detected and the abnormality is detected, so that the abnormality can be detected more precisely and the reliability of the protection circuit is further improved.

Embodiment 8 FIG.
FIG. 27 shows a circuit diagram of a discharge lamp lighting device according to Embodiment 8 of the present invention. In this eighth embodiment, a power source obtained by rectifying and smoothing a commercial AC power source is used as the DC power source E in the above seventh embodiment. In order to prevent the electric light LA from being extinguished, the instantaneous power failure countermeasure circuit SH is provided so that the mask function of the protection circuit NP6 becomes effective again. Note that the same or corresponding parts as those in FIG.

  Hereinafter, the power supply portion and the instantaneous power failure countermeasure circuit SH which are characteristic components of the eighth embodiment will be described. In FIG. 27, AC is a commercial AC power source, and this commercial AC power source AC is connected to the diode bridge DB, and the output terminal of this diode bridge DB is connected to the smoothing capacitor C7 and the input terminal of the inverter circuit IV via the separation diode D7. It is connected. Further, an instantaneous power failure countermeasure circuit SH is connected to the output terminal of the diode bridge DB, and this instantaneous power failure countermeasure circuit SH is configured as follows. That is, the pulsating voltage input from the diode bridge DB to the instantaneous power failure countermeasure circuit SH is divided by the resistors R90 and R91, and the voltage of the resistor R91 is connected to the input terminal of the transistor Q90 via the resistor 92. A capacitor C90 is connected in parallel across the resistor R91. Further, the output of the comparator IC4 is connected to the contact point between the resistor R18 and the resistor R19 of the protection circuit NP6, the connection part of the resistors R23 and R24 connected in series to both ends of the control power supply capacitor C1, and the resistors R25 and R26. Are connected to the non-inverting terminal which is the reference voltage input terminal and the inverting terminal which is the detection voltage input terminal of the comparator IC4, respectively, and the collector of the transistor Q90 is further connected to the inverting terminal of the comparator IC4.

  Hereinafter, the operation of the instantaneous power failure countermeasure circuit SH will be described. First, considering the case where the commercial AC power supply AC stably supplies power, in FIG. 27, the AC current input from the commercial AC power supply AC to the diode bridge DB is rectified to a DC current by the diode bridge DB. Further, after being smoothed by the smoothing capacitor C7, it is inputted to the inverter circuit IV and functions as a DC power source. On the other hand, since the base current is always supplied from the commercial AC power supply AC to the transistor Q90 via the diode bridge DB, the resistor R90, and the resistor R92 during this period, the transistor Q90 is always turned on. As a result, the output of the comparator IC4 is The mask circuit MSK is turned off and the mask circuit MSK functions, and the discharge lamp LA is stably lit after the commercial AC power supply AC is turned on by the same circuit operation as in the seventh embodiment of FIG.

  Next, the operation of the instantaneous power failure countermeasure circuit SH in the case where an instantaneous power failure that causes the discharge lamp LA to be extinguished for a moment during the lighting of the discharge lamp LA will be described. First, during normal lighting of the discharge lamp LA, as in the seventh embodiment, the transistor Q3 of the protection circuit NP6 is on and the transistor Q4 is off. In this state, when an instantaneous power failure occurs in the commercial AC power supply AC and the discharge lamp LA is extinguished for a moment, this corresponds to the non-lighting state described in the second embodiment, so that the transistor Q3 of the protection circuit NP6 is turned off. However, at this time, since the pulsating voltage output of the diode bridge DB becomes zero due to an instantaneous power failure, the base current supplied from the pulsating voltage output to the transistor Q90 via the resistors R90 and R92 is momentarily cut off. The transistor Q90 is turned off for a moment.

  Here, the resistance values of the resistors R23, R24, R25, and R26 are set so that the inverting input terminal voltage of the comparator IC4 is higher than that of the non-inverting input terminal. The output terminal is momentarily inverted, that is, L0. Thus, since the electric charge stored in the capacitor C12 of the timer circuit TM is instantaneously discharged, the transistor Q5 is turned off, the transistor Q4 is turned on, and the mask circuit MSK is automatically reset. When the power failure is restored, the transistor Q90 is turned on and the mask circuit MSK starts to function, and the transistor Q4 remains on until the capacitor C12 is charged again and charged to the zener voltage of the constant voltage diode DZ3. As a result, the mask circuit MSK functions for a certain period of time after the power failure is restored. As a result, even if the discharge lamp LA is turned off momentarily due to an instantaneous power failure and the transistor Q3 of the protection circuit NP6 is turned off once, the mask circuit MSK is restarted. Thereafter, the oscillation stop signal is not output from the protection circuit NP6 to the IV control circuit IC1, and the discharge lamp is reliably turned on.

  As described above, in the eighth embodiment, since the instantaneous power failure countermeasure circuit SH that automatically resets the mask circuit MSK in conjunction with a power failure is added, for example, the commercial AC power supply AC is used as the DC power supply for the inverter circuit IV. Even when an instantaneous power failure occurs in the commercial AC power supply AC, such as when using a rectified and smoothed one, this mask circuit can function effectively again after the power failure is restored, and it is linked to the power supply recovery. As a result, the discharge lamp LA can be reliably turned on again, and the protection function of the protection circuit NP6 can be applied as it is.

  In particular, in the eighth embodiment, since the instantaneous power failure countermeasure circuit SH is configured to rapidly discharge the charge of the capacitor C12, the mask circuit MSK is formed at a higher speed than when the charge of the capacitor C12 is discharged through the resistor R19. It can be reset and can respond to fast phenomena such as instantaneous power outages.

  In the above description, the operation and effect of the instantaneous power failure countermeasure circuit SH with respect to the instantaneous power failure have been described. However, from the operation principle, the instantaneous power failure countermeasure circuit SH functions effectively even in a normal power failure other than the instantaneous power failure. Is clear. It is also clear that this is effective not only for a power failure where the voltage is completely zero, but also for a so-called sag in which the voltage drops.

Embodiment 9 FIG.
FIG. 28 shows a circuit diagram of a discharge lamp lighting device according to Embodiment 9 of the present invention. In the ninth embodiment, a voltage resonance type monolithic circuit is applied as the inverter circuit IV2. A parallel resonance circuit including an oscillation transformer T2 and a resonance capacitor C31 is connected instead of the switching element Q1, and the IV control circuit IC2 is connected. The oscillation terminal is connected only to the switching element Q2. In addition, the same code | symbol is attached | subjected to the same or an equivalent part as Embodiment 2 (FIG. 9), and description is abbreviate | omitted.

  Hereinafter, a difference in operation between the ninth embodiment and the second embodiment will be described. FIG. 29 shows the voltage waveform applied to the discharge lamp load circuit LAC1 when the discharge lamp LA is normally lit, that is, the high-frequency voltage waveform between the terminals of the switching element Q2, in the ninth embodiment. Due to the resonance operation of the choke T1 and the oscillation transformer T2, this high-frequency voltage waveform becomes a sine half wave (in the second embodiment, a square wave as shown in FIG. 2A). Since this is exactly the same as in the second embodiment, the change in the voltage of the coupling capacitor C4 when the discharge lamp LA is normal and abnormal is the same, and therefore the protection circuit NP3 is a voltage resonance type monolithic circuit like this. The discharge lamp lighting device adopting the above can be applied in the same manner as described above, and can be protected.

Embodiment 10
FIG. 30 shows a circuit diagram of a discharge lamp lighting device according to Embodiment 10 of the present invention. In the tenth embodiment, in order to reduce the electrode loss during lighting of the discharge lamp LA, the starting capacitor C3 of the second embodiment (FIG. 9) is replaced with two separate starting capacitors C8 and C9 (the combined capacity of C8 and C9). 1 is separated from the discharge lamp LA on the side of the switching element Q2 with respect to the discharge lamp LA. In addition, the same code | symbol is attached | subjected to FIG. 9 and an equivalent part, and description is abbreviate | omitted.

Thus, according to the tenth embodiment, the starting capacitor C3 is distributed to the plurality of separated starting capacitors C8 and C9, and at least one of them is disposed on the switching element Q2 side with respect to the discharge lamp LA. When the discharge lamp LA is normally lit, the high-frequency current flowing through the ballast choke T1 is distributed and flows in both the separation starting capacitor C8 (equal to the electrode current flowing in the electrodes F1 and F2) and the separation starting capacitor C9. Since the current flowing through the capacitor C9 bypasses the electrodes F1 and F2, the power consumed by the electrode of the discharge lamp LA (electrode loss) is reduced, and the energy efficiency is improved compared to the second embodiment.
Further, the operation and effect of the protection circuit NP3 can be expressed by an equivalent circuit similar to that of the second embodiment in the tenth embodiment, and the same protection operation and effect as those of the previous embodiments can be obtained. Can do.

  Further, as in the fourth embodiment (FIG. 16), in the discharge lamp lighting device that performs dimming by the frequency control circuit FC2, the voltage between both electrodes and the frequency of the discharge lamp LA are reduced in accordance with the dimming operation of the discharge lamp LA. As a result, the current of the starting capacitor increases as compared with that when all light is lit. Therefore, if this configuration in which the starting capacitor is dispersed is applied to such a discharge lamp lighting device, the current of the starting capacitor is increased. There is also an effect that it is possible to suppress an increase in electrode loss due to a dimming operation and a rapid increase in electrode loss.

  In the tenth embodiment (FIG. 30), the circuit provided with the protection circuit NP3 and the like has been described. However, the effect of the separate starting capacitors C8 and C9 is an inverter circuit as is apparent from the operation principle. This is common to discharge lamp lighting devices to which IV is applied, and the same effect can be obtained regardless of the presence or absence of the protection circuit and the instantaneous power failure countermeasure circuit SH.

Embodiment 11
FIG. 31 shows a circuit diagram of a discharge lamp lighting device according to Embodiment 11 of the present invention. In the eleventh embodiment, the discharge lamp load circuit LAC5 is added to the discharge lamp load circuit including the discharge lamp LA (starting capacitor C3 in parallel), the coupling capacitor C4, and the ballast choke T1 as in the fifth embodiment. A discharge lamp load circuit including two discharge lamps LAY and LAZ (starting capacitors C3Y and C3Z in parallel), coupling capacitors C4Y and C4Z, and ballast chokes T1Y and T1Z are connected in parallel.
Further, in the case where a plurality of discharge lamp load circuits are provided, in the fifth embodiment, the comparator unit and the voltage detection unit are individually provided for the increase in the number of discharge lamp load circuits. Dividing the voltage detection unit into two parts, that is, a first voltage detection unit that detects a voltage when the coupling capacitor rises and a second voltage detection unit that detects a voltage when the coupling capacitor falls. Thus, it is possible to detect the coupling voltage of one inverter in parallel lighting only by increasing the number of the voltage dividing resistors and the backflow prevention diodes by the amount increased by the discharge lamp load circuit. In addition, the same code | symbol is attached | subjected to the same or equivalent part as the said Embodiment 5, and description is abbreviate | omitted.

Hereinafter, a detailed configuration of the voltage detection unit VIN will be described.
The voltage detection unit VIN of the eleventh embodiment detects the rising voltages of the coupling capacitors C4, C4Y, and C4Z, converts them into DC voltages, and inputs the detected voltages to the inverting input terminal of the first comparator IC2. The second voltage input to the non-inverting input terminal of the second comparator IC3 by detecting the first voltage detection unit VA and the falling voltage of each of the coupling capacitors C4, C4Y, and C4Z, respectively, and converting them to a DC voltage. It is comprised with the detection part VB.
The first voltage detector VA includes diodes D31, D31Y, D31Z each having an anode connected to each of the coupling capacitors C4, C4Y, C4Z, and a voltage dividing resistor R30 connected to the cathodes of the diodes D31, D31Y, D31Z. A constant voltage diode DZ4 having a cathode connected to the voltage dividing resistor R30, and a voltage dividing resistor R31 having one end connected to the anode of the constant voltage diode DZ4 and the other end grounded. And the voltage dividing resistor R31 are connected to the inverting input terminal of the first comparator IC2.

  The second voltage detection unit VB is a diode D32, D32Y, D32Z having a cathode connected to each coupling capacitor C4, C4Y, C4Z, and a cathode connected to the anode of each diode D32, D32Y, D32Z. The voltage diode DZ5 has a voltage dividing resistor R33 having one end connected to the anode of the constant voltage diode DZ5 and the other end grounded, and the connection point between the constant voltage diode DZ5 and the voltage dividing resistor R33 is a non-inversion of the comparator IC3. Further, the cathode of the constant voltage diode DZ5 is connected to the positive side of the DC power supply E via the voltage dividing resistor R32.

The operation of this eleventh embodiment will be described below.
In FIG. 31, when all of the discharge lamps LA, LAY, and LAZ are normal, the first voltage detection unit VA detects the DC voltage of each of the coupling capacitors C4, C4Y, C4Z, and the first voltage detection unit VA The detection voltage output to the first comparator IC2 is set to be equal to or lower than the reference voltage of the first comparator IC2, and the output of the first comparator IC2 becomes HI.
In the second voltage detection unit VB, a voltage obtained by dividing the DC voltage of the DC power source E by the voltage dividing resistors R32 and R33 and the constant voltage diode DZ5 is output to the second comparator IC2, and the voltage is output to the second comparator IC2. It is set to be equal to or higher than the reference voltage of the comparator IC2, and the output of the second comparator IC3 is also HI. Therefore, since the transistor Q3 is on, the protection circuit NP5 does not output an oscillation stop signal, and the discharge lamps LA, LAY, and LAZ continue to be normally lit.
Thus, when all of the discharge lamps LA, LAY, and LAZ are normal, the voltage detected by the second voltage detector VB is divided by the resistor R32, the constant voltage diode DZ5, and the resistor R33. Voltage.

  Further, when any of the discharge lamps LA, LAY, and LAZ is in an abnormal state, that is, for example, the discharge lamp LA performs rectified lighting 1 and the direct-current voltage of the coupling capacitor C4 of the discharge lamp LA is compared with normal lighting of all light. Is increased, the DC voltage of the coupling capacitor C4 that is the highest voltage is applied to the diode D31 side of the voltage dividing resistor R30 of the first voltage detector VA by the diodes D31, D31Y, and D31Z connected in parallel. It will be. Thus, a DC voltage obtained by further dividing the DC voltage obtained by subtracting the voltage drop of the diode D31 and the voltage of the constant voltage diode DZ4 from the increased voltage of the coupling capacitor C4 (rising voltage) by the resistors R30 and R31 is the first comparator. Since the DC voltage input to the minus pin that is the inverting input terminal of IC2 exceeds the reference voltage that is input to the plus pin that is the non-inverting input terminal of the first comparator IC2, the output of the first comparator IC2 is Invert. Then, the transistor Q3 is turned off, an oscillation stop signal is output to the terminal 5 of the IC1, and the oscillation of the inverter circuit IV is stopped.

Further, when any of the discharge lamps LA, LAY, and LAZ is in an abnormal state, that is, for example, the direct current of the coupling capacitor C4 of the discharge lamp LA as compared with the normal lighting of all light when the discharge lamp LA is rectified lighting 2 or not lighting. When the voltage drops or the DC voltage of the coupling capacitor C4 of all the discharge lamps LA becomes 0V with no discharge lamp LA removed, the DC voltage detected by the second voltage detection circuit VB is 0V. The DC voltage is input as a falling voltage to the plus pin that is the non-inverting input terminal of the second comparator IC3, and the DC voltage is input to the minus pin that is the inverting input terminal of the second comparator IC2. Since it falls below the voltage, the output of the comparator IC3 is inverted. Then, the transistor Q3 is turned off, an oscillation stop signal is output to the terminal 5 of the IC1, and the oscillation of the inverter circuit IV is stopped.
As described above, the DC voltage detected by the second voltage detection circuit VB becomes 0V as the falling voltage because the DC voltage of the coupling capacitor C4 of the discharge lamp LA decreases or becomes 0V. Among the diodes D32, D32Y, and D32Z connected to the voltage dividing resistor R32 that divides the DC voltage, the voltage on the anode side of the backflow prevention diode D32 whose voltage has decreased is increased, and the backflow prevention diode D32 is turned on. This is because the DC voltage of the DC power source E is applied to the coupling capacitor C4 via the voltage dividing resistor R32.

  As described above, according to the eleventh embodiment, in the discharge lamp lighting device having a plurality of discharge lamp load circuits, the rising voltage of each coupling capacitor connected to the voltage detector VIN in the plurality of discharge lamps. The first voltage detection unit VA that detects (the maximum voltage in this embodiment) and the falling voltage (in this embodiment, the minimum voltage is detected and then 0 V is output as the falling voltage) are detected. By dividing into two of the second voltage detection unit VB, it is possible to detect the coupling voltage of one inverter in parallel lighting only by increasing the number of voltage dividing resistors and backflow prevention diodes by the number of discharge lamp load circuits. Thus, the number of parts can be reduced compared to the case where the comparator unit and the voltage detection unit are individually provided by the amount of increase in the discharge lamp load circuit as in the fifth embodiment. . Therefore, in the eleventh embodiment, the number of parts can be reduced as the number of discharge lamp load circuits increases.

Even if the number of discharge lamp load circuits increases, not only the state of the rectifying lighting 1 in which any one of the plurality of discharge lamps is in an abnormal state, that is, the detected voltage is increased compared to when all the lights are normally lit. Thus, it is possible to detect the state of the rectified lighting 2 in which the detection voltage is lower than that in the case where the all-lights are normally lit, and the presence or absence of the discharge lamp in which the detection voltage is 0 V by removing the discharge lamp. In addition, although the presence or absence of a discharge lamp can be detected, the presence or absence of a discharge lamp and the presence or absence of abnormality cannot be distinguished.
The first voltage detector VA outputs the voltage divided by the voltage dividing resistors R30 and R31 and the constant voltage diode DZ4 to the first comparator IC2, and the second voltage detector VB includes each coupling capacitor C4. , C4Y, C4Z, when the voltage is higher than a predetermined voltage, the voltage divided by the voltage dividing resistors R32, R33 and the constant voltage diode DZ5 is output to the second comparator IC3. The difference in the reference voltage between normal lighting and abnormal lighting in the comparators IC2 and IC3 can be set large, and the reliability of the protection circuit is further improved.
In FIG. 31, the case where there are three discharge lamp load circuits is illustrated, but it is needless to say that the present invention can be similarly applied to three or more parallel lighting circuits.

Embodiment 12
FIG. 32 shows a circuit diagram of a discharge lamp lighting device according to Embodiment 12 of the present invention. In this twelfth embodiment, it should be called the first modification of the eleventh embodiment, and the detection position of the voltage of the coupling capacitor of the second voltage detector VB is different from the eleventh embodiment. is there.
That is, in the twelfth embodiment, one end of the backflow prevention diodes D32, D32Y, D32Z of the second voltage detector VB is connected to the starting capacitor side of the discharge lamps LA, LAY, LAZ.
Therefore, when any of the discharge lamps LA, LAY, and LAZ is in an abnormal state, for example, the direct current of the coupling capacitor C4 of the discharge lamp LA is compared with, for example, the discharge lamp LA is rectified lighting 2 or non-lighting and all-light normal lighting. When the voltage drops, the DC voltage detected by the second voltage detection circuit VB becomes 0 V, the DC voltage is input to the plus pin that is the non-inverting input terminal of the comparator IC3, and the DC voltage is input to the inverting input of the comparator IC2. Since the voltage is lower than the reference voltage input to the minus pin that is a terminal, the output of the comparator IC3 is inverted. Then, the transistor Q3 is turned off, an oscillation stop signal is output to the terminal 5 of the IC1, and the oscillation of the inverter circuit IV is stopped.

  However, for example, in the case of no load with the discharge lamp F1Z removed, the circuit of the coupling capacitor C4Z and the backflow prevention diode D32Z of the discharge lamp LAZ is cut off in the second voltage detection circuit VB. All of LAY and LAZ are the same as in a normal state, and the voltage detected by the second voltage detector VB is obtained by dividing the DC voltage of the DC power supply E by the voltage dividing resistor R32, the constant voltage diode DZ5, and the voltage dividing resistor R33. Since the voltage is input to the second comparator IC3, the output of the second comparator IC3 remains HI, and the transistor Q3 is on, so that the protection circuit NP5 outputs an oscillation stop signal. There is no output. Therefore, when the number of discharge lamp load circuits is increased, the presence or absence of the discharge lamp is not detected in the case of no load with any discharge lamp removed.

Embodiment 13
FIG. 33 shows a circuit diagram of a discharge lamp lighting device according to Embodiment 13 of the present invention. In this thirteenth embodiment, it should be called another modified example of the eleventh embodiment, and the backflow prevention diode constituting the OR circuit of the first voltage detection unit VA and the second voltage detection unit VB is provided. The position to be provided is different from that in the eleventh embodiment.
In the first voltage detector VA of the thirteenth embodiment, the voltage dividing resistors R40, R42, and R44 connected to the coupling capacitors C4, C4Y, and C4Z, and the voltage dividing resistors R40, R42, and R44 have cathodes, respectively. Each of the voltage regulator diodes DZ4, DZ4Y, DZ4Z connected to each other, voltage dividing resistors R41, R43, R45 having one end connected to the anode of each of the voltage regulator diodes DZ4, DZ4Y, DZ4Z and the other end grounded, and each constant voltage Backflow blocking diodes D31, D31Y, having anodes connected to the connection points of the diodes DZ4, DZ4Y, DZ4Z and the voltage dividing resistors R41, R43, R45, respectively, and cathodes connected to the inverting input terminals of the first comparator IC2, respectively. D31Z.

  The second voltage detector VB shares the voltage dividing resistors R40, R42, R44, the constant voltage diodes DZ4, DZ4Y, DZ4Z and the voltage dividing resistors R41, R43, R45 of the first voltage detector VA. The backflow prevention diodes D32, D32Y, D32Z and the backflow prevention diodes D32, D32Y, D32Z, whose cathodes are connected to the connection points of the constant voltage diodes DZ4, DZ4Y, DZ4Z and the voltage dividing resistors R41, R43, R45, respectively. Of the voltage diode DZ5, and a voltage dividing resistor R46 having one end connected to the anode of the voltage diode DZ5 and the other end grounded. The connection point of the resistor R46 is connected to the non-inverting input terminal of the second comparator IC3, and further a constant voltage diode It is connected to the positive side of the DC power source E Z5 cathode of through the voltage dividing resistor R32.

In the thirteenth embodiment, the DC voltage of each of the coupling capacitors C4, C47Y, and C4Z is divided between the voltage dividing resistor R40, the constant voltage diode DZ4, and the voltage dividing resistor R41, and the voltage dividing resistor R43 and the constant voltage diode DZ4Y. The voltage dividing circuit of the voltage resistor R43, the voltage dividing resistor R44, the constant voltage diode DZ4Z, and the voltage dividing resistor R45 respectively divide the voltage, and the divided voltage is supplied to the first comparator unit IC2 as a backflow prevention diode D31, Each voltage is input via D31Y and D31Z, and the DC voltage of the DC power source E is divided by the voltage dividing circuit of the voltage dividing resistor R32, the constant voltage diode DZ5, and the voltage dividing resistor R46, and the divided voltage is connected to each coupling capacitor. Input to C4, C47Y, C4Z via backflow prevention diodes D32, D32Y, D32Z, respectively. , Reverse-blocking diode D31, D31Y, D31Z, D32, D32Y, D32Z is effective which can be used having a low withstand voltage than that of the eleventh embodiment.
Since other operations and effects are the same as those of the eleventh embodiment, description of the operations and effects is omitted.

The circuit diagram which shows the structure of the discharge lamp lighting device of Embodiment 1 of this invention. The voltage waveform figure between the terminals of the switching element showing operation | movement of the discharge lamp lighting device of Embodiment 1 of this invention. The equivalent circuit diagram at the time of all-light normal lighting of the discharge lamp lighting device of Embodiment 1 of this invention. The lamp current waveform figure at the time of all-light normal lighting and rectification lighting of the discharge lamp lighting device of Embodiment 1 of this invention. The equivalent circuit figure at the time of the rectification lighting of the discharge lamp lighting device of Embodiment 1 of this invention. The equivalent circuit figure at the time of the rectification lighting of the discharge lamp lighting device of Embodiment 1 of this invention. The equivalent circuit diagram at the time of non-lighting of the discharge lamp lighting device of Embodiment 1 of the present invention. The comparison figure which shows the change of the electric potential of the discharge lamp lighting device of Embodiment 1 of this invention. The circuit diagram which shows the structure of the discharge lamp lighting device of Embodiment 2 of this invention. The equivalent circuit diagram at the time of all-light normal lighting of the discharge lamp lighting device of Embodiment 2 of this invention. The equivalent circuit figure at the time of the rectification lighting of the discharge lamp lighting device of Embodiment 2 of this invention. The equivalent circuit figure at the time of the rectification lighting of the discharge lamp lighting device of Embodiment 2 of this invention. The equivalent circuit figure at the time of non-lighting of the discharge lamp lighting device of Embodiment 2 of this invention. The comparison figure which shows the change of the electric potential of the discharge lamp lighting device of Embodiment 1 and Embodiment 2 of this invention. The circuit diagram which shows the structure of the discharge lamp lighting device of Embodiment 3 of this invention. The circuit diagram which shows the structure of the discharge lamp lighting device of Embodiment 4 of this invention. The equivalent circuit figure at the time of the dimming lighting of the discharge lamp lighting device of Embodiment 4 of this invention. The equivalent circuit figure at the time of the dimming lighting of the discharge lamp lighting device of Embodiment 1 of this invention. The circuit diagram which shows the structure of the discharge lamp lighting device of Embodiment 5 of this invention. The circuit diagram which shows the structure of the discharge lamp lighting device of Embodiment 6 of this invention. The LC series resonance curve figure showing circuit operation of the discharge lamp lighting device of Embodiment 6 of this invention. The lamp voltage waveform diagram and transistor operation | movement diagram showing the circuit operation | movement of the discharge lamp lighting device of Embodiment 6 of this invention. The lamp voltage waveform diagram and transistor operation | movement diagram showing the circuit operation | movement of the discharge lamp lighting device of Embodiment 6 of this invention. The circuit diagram which shows the structure of the discharge lamp lighting device of Embodiment 7 of this invention. The LC series resonance curve figure showing the circuit operation of the discharge lamp lighting device of Embodiment 7 of this invention. The high frequency current waveform figure of the discharge lamp lighting device of Embodiment 7 of this invention. The circuit diagram which shows the structure of the discharge lamp lighting device of Embodiment 8 of this invention. The circuit diagram which shows the structure of the discharge lamp lighting device of Embodiment 9 of this invention. The voltage waveform figure between the terminals of the switching element showing operation | movement of the discharge lamp lighting device of Embodiment 9 of this invention. The circuit diagram which shows the structure of the discharge lamp lighting device of Embodiment 10 of this invention. The circuit diagram which shows the structure of the discharge lamp lighting device of Embodiment 11 of this invention. The circuit diagram which shows the structure of the discharge lamp lighting device of Embodiment 12 of this invention. The circuit diagram which shows the structure of the discharge lamp lighting device of Embodiment 13 of this invention. The circuit diagram which shows the structure of the conventional discharge lamp lighting device. The voltage waveform figure showing operation | movement of the conventional discharge lamp lighting device.

Explanation of symbols

E DC power supply IV, IV2 Inverter circuit IC1, IC2 IV control circuit (switching element control circuit)
Q1, Q2 Switching element LA Discharge lamp LAC1, LAC2, LAC3, LAC4 Discharge lamp load circuit T1 Ballast choke C4 Coupling capacitor NP1, NP2, NP3, NP4, NP5, NP6 Protection circuit VIN, VIN2 Voltage detection part COMP, COMP2 Comparator part VOUT control signal output unit R10, R20 detection resistor (voltage dividing resistor)
R11, R21 Detection resistance (voltage dividing resistance)
DZ4 Constant voltage diode IC2 Comparator IC3 Comparator FC1, FC2, FC3 Frequency control circuit R99 Variable resistor MSK Mask circuit AP Over resonance detection circuit SH Instantaneous power failure countermeasure circuit (power failure countermeasure circuit)
AC AC power supply DB Diode bridge C7 Smoothing capacitor C3 Starting capacitor C8, C9 Separate starting capacitor

Claims (3)

DC power supply,
A switching element that switches a direct current supplied from the direct current power source to generate a high-frequency current;
A switching control circuit for controlling switching of the switching element;
A plurality of discharge lamp load circuits connected in parallel to the switching element, each having a choke coil, a discharge lamp and a coupling capacitor connected in series;
A first voltage detection unit that converts a maximum voltage among the voltages of the coupling capacitors of the plurality of discharge lamp load circuits to a first DC voltage;
A second voltage detector for converting a minimum voltage to a second DC voltage among the voltages of the coupling capacitors of the plurality of discharge lamp load circuits;
When the first DC voltage detected by the first voltage detection unit exceeds a first reference voltage, a first comparator unit that outputs the first control signal, and the second voltage detection unit A second comparator that outputs the second control signal when the detected second DC voltage falls below a second reference voltage;
A protection circuit that outputs a signal for suppressing the high-frequency current to the switching element circuit when either the first or second control signal is output;
With
The first voltage detection unit includes a voltage dividing resistor that divides a voltage of each coupling capacitor in a plurality of discharge lamp load circuits, a constant voltage diode connected to the voltage dividing resistor, the voltage dividing resistor, and each of the voltage dividing resistors. Comprising a backflow prevention diode provided between the coupling capacitors,
A voltage divided by the voltage dividing resistor and the constant voltage diode is output to the first comparator unit;
The second voltage detector includes a voltage dividing resistor for dividing a predetermined voltage, a constant voltage diode connected to the voltage dividing resistor, a cathode of the constant voltage diode, and each cup in the plurality of discharge lamp load circuits. Comprising a ring capacitor and a backflow prevention diode provided between each discharge lamp,
When the minimum voltage among the voltages of the respective coupling capacitors is higher than the Zener voltage of the constant voltage diode, the voltage divided by the voltage dividing resistor and the constant voltage diode is output to the second comparator unit,
When the minimum voltage among the voltages of the coupling capacitors is lower than the Zener voltage of the constant voltage diode, the voltage supplied from the predetermined voltage has the minimum voltage via the reverse current blocking diode. A discharge lamp lighting device configured to be applied to a capacitor and not applied to the second comparator unit . Each discharge lamp in the plurality of discharge lamp load circuits has a first filament and a second filament,
In each of the plurality of discharge lamp load circuits, between the other end of the first filament on the side to which a high-frequency current is supplied and the other end of the two filaments on the side to which a coupling capacitor is connected. Connect the starting capacitor,
The discharge lamp lighting device according to claim 1, wherein the cathode of the second voltage detecting unit of the reverse-blocking diode and being connected to the other end of the second filament. DC power supply,
A switching element that switches a direct current supplied from the direct current power source and generates a high-frequency current;
A switching control circuit for controlling switching of the switching element;
A plurality of discharge lamp load circuits connected in parallel to the switching element, each having a choke coil, a discharge lamp and a coupling capacitor connected in series;
A first voltage detection unit that converts a maximum voltage among the voltages of the coupling capacitors of the plurality of discharge lamp load circuits to a first DC voltage;
A second voltage detector for converting a minimum voltage to a second DC voltage among the voltages of the coupling capacitors of the plurality of discharge lamp load circuits;
A first comparator that outputs the first control signal when the first DC voltage detected by the first voltage detector exceeds a first reference voltage; and
A second comparator that outputs the second control signal when the second DC voltage detected by the second voltage detector falls below a second reference voltage;
A protection circuit that outputs a signal for suppressing the high-frequency current to the switching element circuit when either the first or second control signal is output;
With
The first voltage detection unit includes a first voltage dividing resistor that divides the voltage of each coupling capacitor in a plurality of discharge lamp load circuits, and a first constant voltage diode connected to the first voltage dividing resistor. When, and a respective of said first constant voltage diode and the first first reverse-blocking diode respectively provided between the comparator unit,
A voltage divided by the first voltage dividing resistor and the first constant voltage diode is output to the first comparator unit via the first backflow prevention diode;
It said second voltage detecting unit includes a second voltage dividing resistor for dividing a predetermined voltage, a second constant voltage diode, an anode and the second constant-voltage diode of each of said first zener diode A second backflow blocking diode connected between the cathodes of
When the maximum value of each of the first output voltage of the constant voltage diode is higher than the reference voltage of the second comparator unit is divided by the second voltage dividing resistor and the second constant voltage diode Output the voltage to the second comparator section,
When the minimum value of the output voltage of each of the first constant voltage diodes is lower than the Zener voltage of the second constant voltage diode, the predetermined voltage is used as the second reverse current blocking diode and the first voltage detection. voltage through the first dividing resistor and the first constant voltage diode parts is applied to the minimum of the coupling capacitor, and wherein the second comparator unit is configured so as not to be applied Discharge lamp lighting device.

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