JP2000208289A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a discharge lamp lighting device capable of accurately detecting the last stage of a discharge lamp lifetime. SOLUTION: In this device, one end of an inductor L1 is connected to a connection point of switching elements Q1, Q2, while one end of an inductor L2 is connected to a connection point of switching elements Q3, Q4. Inductances of the inductors L1, L2 are set to nearly equal values. A discharge lamp FL is connected between the other end of the inductor L1 and the other end of the inductor L2 through a DC cutting capacitor Cc, while a series circuit of capacitors C1, C2 having nearly equal capacitances is connected between both ends of the discharge lamp FL. A lifetime detection circuit 11 detects a DC component superimposed on a voltage between both the ends of the discharged lamp FL during abnormal lighting from a voltage Va of the connecting point of the capacitors C1, C2, so as to detect the last stage of a lifetime of the discharge lamp FL.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device.

[0002]

2. Description of the Related Art FIG.
Some have a circuit having the configuration shown in FIG. This circuit includes a DC power supply VDC, a series circuit of switch elements Q1 and Q2 and a series circuit of switch elements Q3 and Q4 connected between the positive electrode and the negative electrode of the DC power supply VDC, and each of the switch elements Q1 to Q4. An inductor L is connected between diodes D1 to D4 connected in anti-parallel, and a connection point between switch elements Q1 and Q2 and a connection point between switch elements Q3 and Q4.
A current detection transformer T1 connected to a primary winding via an LC series resonance circuit of the capacitor 10 and a capacitor C10, a discharge lamp FL connected in parallel with the capacitor C10, and a secondary winding of the transformer T1. A rectifying / smoothing circuit 14 for rectifying and smoothing a current, and a control circuit 10 for outputting control signals a to d for controlling on / off of the switching elements Q1 to Q4 to control terminals of the switching elements Q1 to Q4 are provided.

The control circuit 10 includes a set of switch elements Q1 and Q4 arranged at diagonal positions and switch elements Q2 and Q4.
By alternately turning on and off the set of 3 at high frequency,
The connection point A between the switching elements Q1 and Q2 and the switching element Q
3 and Q4 to generate a high-frequency rectangular wave voltage, and this high-frequency rectangular wave voltage
The LC series resonance circuit of the capacitor C10 vibrates at a high frequency, and the discharge lamp FL is lit at a high frequency.

In the secondary winding of the transformer T1, a high-frequency AC current proportional to the resonance current I1 flowing through the LC series resonance circuit of the inductor L10 and the capacitor C10 is generated. The DC component superimposed on the resonance current I1 is detected by rectification and smoothing. Here, when the discharge lamp FL enters the Emiless state at the end of life and starts half-wave discharge (asymmetric discharge), the DC component superimposed on the resonance current I1 increases. Since the detected value of the DC component exceeds the predetermined threshold value, the end-of-life state of the discharge lamp FL is detected, and the switch elements Q1 to Q4 are detected.
The protection operation is performed by controlling on / off of Q4.

[0005] Further, as this kind of discharge lamp lighting device, there is a device having a circuit having a configuration shown in FIG. In the above-described discharge lamp lighting device, the connection point A of the switch elements Q1 and Q2
Although a transformer T1 for current detection is connected between the switching element Q3 and the connection point B of the switching element Q3 via an LC series resonance circuit of an inductor L10 and a capacitor C10,
In this circuit, a DC cut capacitor Cc is connected between both connection points A and B through an LC series resonance circuit of an inductor L10 and a capacitor C10, and a difference between the voltages Vcc1 and Vcc2 across the capacitor Cc is detected / compared. Circuit 15
Detected by Here, when the discharge lamp FL enters the Emiless state at the end of life and starts half-wave discharge (asymmetric discharge), the DC component superimposed on the resonance current flowing through the resonance circuit increases, and the difference voltage between the voltages Vcc1 and Vcc2 increases. To increase.
Therefore, the control circuit 10 detects the end-of-life state of the discharge lamp FL since the detection value of the difference voltage between the voltages Vcc1 and Vcc2 exceeds the predetermined threshold value, and
The protection operation is performed by controlling on / off of Q4.

Further, as this kind of discharge lamp lighting device, there is one having a circuit having a configuration shown in FIG.
-322169). In this circuit, in the circuit shown in FIG. 11 described above, one end of the high-pressure discharge lamp DL is connected to the connection point A of the switch elements Q1 and Q2 via the inductor L11, and the other end of the high-pressure discharge lamp DL is connected to the inductor L12. Connection point B of switch elements Q3 and Q4
And a capacitor C11 between both ends of the high-pressure discharge lamp DL.
Are connected. Here, the inductance values of the inductors L11 and L12 are set to substantially the same value. In addition,
Although FIG. 13 omits the control circuit 10 for controlling the on / off of the switch elements Q1 to Q4, the control circuit 1
0 indicates a period in which the switching elements Q2 and Q3 are turned off and the switching elements Q1 and Q4 are repeatedly turned on and off at a high frequency, and a period in which the switching elements Q1 and Q4 are turned off and the switching elements Q2 and Q3 are turned on and off at a high frequency. The period and the period are alternately repeated at a low frequency.

Voltages V11 and V12 across high-pressure discharge lamp DL
Are detected by a maximum value detection circuit 16 composed of diodes D7, D8 and a resistor R10, and the potentials V11, V
12, the higher voltage is output as the output voltage V13.

Here, since the inductors L11 and L12 having substantially equal inductance values are provided at both ends of the high-pressure discharge lamp DL, the voltage fluctuations of the voltages V11 and V12 across the high-pressure discharge lamp DL due to the high-frequency switching of the switch elements Q1 to Q4. Disappears. By the way, the lamp voltage is the voltage V
11 and V12, the voltage between both ends V11 and V12
For example, a differential amplifier is used to detect the twelve differential voltages, but the voltage fluctuations of the terminal voltages V11 and V12 increase, and the power supply voltage chopped at the switching frequency is superimposed on each of the terminal voltages V11 and V12. In such a case, the ability of the differential amplifier to remove the common-mode component decreases as the frequency of the common-mode component increases, so that the common-mode component is superimposed on the output of the differential amplifier, and an integrating circuit is added to remove the common-mode component. There is a need. However, in this circuit, since the inductance values of the inductors L11 and L12 are made substantially equal to each other, the voltage fluctuations of the voltages V11 and V12 are eliminated, so that the integration circuit becomes unnecessary and the detection delay due to the integration operation of the integration circuit is eliminated. , The lamp voltage of the high-pressure discharge lamp DL can be detected at high speed and with high accuracy, and the control circuit 10 performs on / off control of the switch elements Q1 to Q4 according to a change in the discharge state of the high-pressure discharge lamp DL, And fluctuations in lamp current.

[0009]

Among the discharge lamp lighting devices described above, in the discharge lamp lighting device shown in FIG. 11, the rectification / smoothing circuit 14 rectifies and smoothes a high-frequency resonance current I1 flowing through the resonance circuit. Since the end of life of the discharge lamp FL is detected by detecting the DC component superimposed on the resonance current I1, there is a problem that a detection delay or a detection error occurs when rectifying and smoothing the high-frequency current.

In the discharge lamp lighting device shown in FIG.
The difference detection / comparison circuit 15 is a DC cut capacitor C.
c, the voltages Vcc1 and Vcc2 are detected.
The end-of-life state of the discharge lamp FL is detected by comparing the difference voltage between Vcc1 and Vcc2 with a predetermined threshold value. However, since the voltages Vcc1 and Vcc2 are high-frequency AC voltages, it is necessary to handle the high-frequency AC voltage. There has been a problem that the circuit configuration of the difference detection / comparison circuit 15 is complicated and a detection error occurs.

Further, in the discharge lamp lighting device shown in FIG. 13, when the switching elements Q2 and Q3 are turned off, the switching element Q
1, Q4 at a high frequency, and switching elements Q2, Q4 when switching elements Q1, Q4 are off.
Since the voltage V11, V12 of the high-pressure discharge lamp DL is oscillated at a low frequency by alternately repeating a period during which the on / off of 3 is repeated at a high frequency at a low frequency, the discharge lamp is lit with a high-frequency alternating current. There was a problem that it could not be applied when making it.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a discharge lamp lighting device capable of accurately detecting the end-of-life state of a discharge lamp that is operated by high-frequency AC. Is to provide.

[0013]

In order to achieve the above object, according to the present invention, a series circuit of first and second switch means connected between a positive electrode and a negative electrode of a DC power supply, A series circuit of third and fourth switch means connected between the positive electrode and the negative electrode of the DC power supply; and first to fourth rectifier means connected in anti-parallel with the first to fourth switch means, respectively. A first impedance element having one end connected to a connection point of the first and second switch means, a second impedance element having one end connected to a connection point of the third and fourth switch means, A load circuit including at least a discharge lamp connected between the other end of the first impedance element and the other end of the second impedance element via a capacitor; and the first and second load circuits connected between both ends of the load circuit. 2 impedance elements and And a control circuit for controlling the on / off of the first to fourth switch means to supply high-frequency AC power to the load circuit, and a third and fourth impedance element. And a life detecting means for detecting an end-of-life state of the discharge lamp from an electric quantity at a connection point of the elements, wherein the life detecting means divides a voltage between both ends of the discharge lamp by the third and fourth impedance elements. Since the end-of-life state of the discharge lamp is detected from the amount of electricity at the pressurized partial pressure point, the DC component superimposed at the time of abnormal lighting can be directly detected. Detection errors can be eliminated.

According to the second aspect of the present invention, a series circuit of the first and second switch means connected between the positive electrode and the negative electrode of the DC power supply, and a series circuit connected between the positive electrode and the negative electrode of the DC power supply. A series circuit of third and fourth switch means;
First to fourth rectifiers respectively connected in anti-parallel with the first switch, a first impedance element having one end connected to a connection point of the first and second switch, and third and fourth rectifiers. A second impedance element having one end connected to a connection point of the switch means, and at least a discharge lamp connected via a capacitor between the other end of the first impedance element and the other end of the second impedance element. And third and fourth load circuits connected between both ends of the load circuit.
A fifth impedance element connected between both ends of the load circuit to form a resonance circuit together with the first and second impedance elements;
A control circuit for controlling the on / off of the switch means to supply high-frequency AC power to the load circuit; and a life detecting means for detecting an end-of-life state of the discharge lamp from an electric quantity at a connection point of the third and fourth impedance elements. It is characterized by having
Similarly to the first aspect of the invention, the life detecting means detects the end-of-life state of the discharge lamp from the amount of electricity at a voltage dividing point obtained by dividing the voltage across the discharge lamp by the third and fourth impedance elements. Therefore, it is possible to directly detect the DC component superimposed at the time of abnormal lighting, and it is possible to eliminate a detection delay and a detection error that occur when a high-frequency component is detected.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the first and second impedance elements have substantially the same impedance, and the first and second impedance elements have substantially the same impedance. Since the impedance elements are provided at both ends of the load circuit, it is possible to eliminate the fluctuation of the voltage between both ends of the discharge lamp due to the switching of the first to fourth switch means.

According to a fourth aspect of the present invention, in the first or second aspect, the impedance of the third impedance element is substantially equal to the impedance of the fourth impedance element, and the third and fourth impedance elements are connected. Since the potential at the point is a voltage obtained by averaging the voltages at both ends of the discharge lamp, the high-frequency component is canceled and the DC component can be directly detected.

According to a fifth aspect of the present invention, in the first or second aspect of the invention, the life detecting means detects an end-of-life state of the discharge lamp from a DC component of an electric quantity at a connection point of the third and fourth impedance elements. Since the life detecting means directly detects the DC component, there is no need to provide a circuit for rectifying and smoothing the high frequency component as in the case of detecting the high frequency component. The detection delay and the detection error which occur in the above can be eliminated.

According to a sixth aspect of the present invention, in the first or second aspect of the present invention, the discharge lamp has a filament electrode at both ends, and is connected between the other end of the first impedance element and the other end of the second impedance element. A power supply side terminal of both filament electrodes is connected via a capacitor therebetween, and a series circuit of third and fourth impedance elements is connected between the non-power supply side terminals of both filament electrodes. It is.

According to a seventh aspect of the present invention, in the first to sixth aspects of the present invention, the DC power supply connects an AC power supply between AC input terminals of a full-wave rectifier. A DC output terminal of a full-wave rectifier is connected between both ends of any of the switch means via an inductor, and a first and a second
A smoothing capacitor is connected in parallel with the series circuit of the switch means, and a chopper circuit is composed of an inductor, a smoothing capacitor, the switch means, and rectifying means connected in anti-parallel to the switch means. By performing the chopper operation, harmonic distortion included in the input current can be reduced.

According to an eighth aspect of the present invention, in the first to sixth aspects of the present invention, the DC power supply is a series circuit of fifth and sixth rectifiers in anti-parallel with the series circuit of the first and second switch means. And an inductor is connected between one of the connection points of the first and second switch means or the connection point of the third and fourth switch means and the connection point of the fifth and sixth rectifier means. And a smoothing capacitor connected in parallel with the series circuit of the first and second switch means. The inductor, the smoothing capacitor, the switch means, and the rectifier connected in anti-parallel to the switch means. Means constitutes a chopper circuit, and the chopper circuit performs a chopper operation to reduce harmonic distortion included in the input current. In addition, full-wave rectification can be achieved by adding only two rectifiers. It is possible to configure, it is possible to reduce the number of components constituting the circuit as compared with the invention of claim 7, it is possible to reduce the cost.

According to a ninth aspect of the present invention, in the first to eighth aspects, the discharge lamp has an optical path length of about 1400 mm or more and about 2500 mm or less, and a tube diameter of about 18 mm or more and about 29 mm or less. This is a desirable embodiment.

[0022]

(Embodiment 1) FIG. 1 shows a circuit diagram of a discharge lamp lighting device according to this embodiment. The circuit includes a DC power supply VDC, a series circuit of switch elements Q1 and Q2 and a series circuit of switch elements Q3 and Q4 connected in parallel between the positive electrode and the negative electrode of DC power supply VDC, respectively, and switch elements Q1 to Q4. And diodes D1 to D4 connected in anti-parallel with each other, an inductor L1 as a first impedance element having one end connected to a connection point A of the switch elements Q1 and Q2, and a connection point B of the switch elements Q3 and Q4. Inductor L2 as a second impedance element having one end connected thereto, and the other end of inductor L1 and inductor L2
A discharge lamp FL forming a load circuit connected to the other end of the discharge lamp FL via a DC cut capacitor Cc, and a discharge circuit connected between both ends of the discharge lamp FL and forming a resonance circuit together with the inductors L1 and L2. A series circuit of capacitors C1 and C2 as third and fourth impedance elements, and a control circuit 10 for outputting control signals a to d for turning on and off the switch elements Q1 to Q4 to control terminals of the switch elements Q1 to Q4.
And the discharge lamp F from the potential of the connection point of the capacitors C1 and C2.
And a life detecting circuit 11 serving as a life detecting means for detecting the end-of-life state of L. Here, the switching elements Q1 to Q1
Q4 is formed of, for example, a bipolar transistor. First to fourth switch means are constituted by switch elements Q1 to Q4, and first to fourth rectifier means are constituted by diodes D1 to D4. The inductance values of the inductors L1 and L2 are set to substantially equal values, and the capacitances of the capacitors C1 and C2 are also set to substantially equal values.

The life detecting circuit 11 includes capacitors C1, C
2, a capacitor C3 connected between the connection point 2 and the negative terminal of the DC power supply VDC, a reference voltage generator 11a for generating a reference voltage Vr, and a reference voltage generated by the reference voltage generator 11a for generating a voltage across the capacitor C3. And a comparator CP1 for comparing with Vr.

Here, since the voltage across the capacitor C3 is substantially equal to the voltage Va at the connection point between the capacitors C1 and C2, the life detecting circuit 11 calculates the voltage Va at the connection point between the capacitors C1 and C2 from the voltage across the capacitor C3. Can be detected. When the discharge lamp FL is normally lit, the voltage Va =
(VDC / 2) × (C1 + C2) / (C1 + C2 + C
3), the comparator CP1 compares the level of the voltage Va with the level of the reference voltage Vr, and outputs the comparison result to the control circuit 10. The control circuit 10 detects the end-of-life state of the discharge lamp FL from the comparison result of the comparator CP1, controls the on / off of the switch elements Q1 to Q4, and reduces or stops the voltage applied to the discharge lamp FL. I do.

That is, when the on-duties of the switching elements Q1 to Q4 are equal and the discharge lamp FL is operating normally, the voltages V1 and V2 across the discharge lamp FL are as shown in FIG.
As shown in (a) and (b), since high-frequency AC voltages having the same amplitude and opposite phases with respect to the voltage VDC / 2 are centered, the high-frequency component of the voltage Va at the connection point of the capacitors C1 and C2 is canceled. Then, as shown in FIG.
It is detected as a DC voltage of (C / 2) × (C1 + C2) / (C1 + C2 + C3). On the other hand, when the discharge lamp FL enters the Emiless state at the end of its life and the discharge lamp FL starts half-wave discharge (asymmetric discharge), the DC component superimposed on the voltages V1 and V2 increases, and the discharge lamp FL shown in FIGS. ), Voltages V1 and V2 are voltages V1 ′ and V2 ′ (> VDC /
A high-frequency AC voltage having the same amplitude in opposite phases with respect to 2), and a voltage Va that is an average voltage of the voltages V1 and V2.
Is (V1 '+ V2') / 2 (>) as shown in FIG.
(VDC / 2) × (C1 + C2) / (C1 + C2 + C
3)) DC voltage.

Here, the reference voltage Vr generated by the reference voltage generator 11a is, for example, (VDC / 2) × (C1 + C2)
/ (C1 + C2 + C3), the discharge lamp FL
When the discharge lamp FL starts half-wave discharge at the end of the life of the battery and the discharge lamp FL starts half-wave discharge, the voltage Va becomes (VDC / 2) × (C1
+ C2) / (C1 + C2 + C3), and the comparison result between the voltage Va and the reference voltage Vr is not zero. Therefore, the control circuit 10 can detect the end-of-life state of the discharge lamp FL from the comparison result of the comparator CP1. .

As described above, in the discharge lamp lighting device for lighting the discharge lamp FL at high frequency, the life detecting circuit 11 includes the voltage Va at the connection point of the capacitors C1 and C2, that is, the discharge lamp FL.
The voltage obtained by dividing the voltage across L by the capacitors C1 and C2 is detected. At the connection point of the capacitors C1 and C2, the high-frequency AC voltages included in the voltages V1 and V2 across the discharge lamp FL cancel each other, and Since the DC components superimposed on V1 and V2 can be directly detected, there is no detection delay or detection error unlike the case where the DC components are detected by rectifying and smoothing the high-frequency AC voltage. Since a circuit and a smoothing circuit are not required, the circuit configuration is simplified, and the cost can be reduced. Further, if the resonance inductors L1 and L2 are configured by winding windings around one bobbin, a core can be shared by the inductors L1 and L2, and the cost can be further reduced.

(Embodiment 2) FIG. 4 is a circuit diagram showing a discharge lamp lighting device according to this embodiment. In the discharge lamp lighting device of the first embodiment, the DC voltage of the DC power supply VDC is converted to a high-frequency AC voltage by a full-bridge inverter and applied to the discharge lamp FL. In the present embodiment, however, the commercial AC power supply AC is connected to a filter circuit. A full-wave rectifier connected between the AC input terminals of a full-wave rectifier 12 composed of a diode bridge via F and a chopper choke (inductor) L3 between both ends of a switch element Q2 also serving as a chopper switch means. 12 DC output terminals, and switch elements Q1,
A DC power supply is configured by connecting a smoothing capacitor C0 in parallel with the series circuit of Q2 and the series circuit of switch elements Q3 and Q4. Further, an on-duty ratio control circuit 13 for generating a duty control signal for controlling the on-duty ratio of the switch element Q2 is provided, and the reference voltage generating unit 11a is configured to generate a duty control signal based on the duty control signal generated by the on-duty ratio control circuit 13. The voltage value of the reference voltage Vr is changed. Here, choke L3 for chopper,
A boost chopper circuit is constituted by the switch element Q2, the diode D1, and the smoothing capacitor C0. Harmonic distortion of the input current can be reduced by the chopper operation of the boost chopper circuit. Note that the same components as those of the discharge lamp lighting device according to the first embodiment described above are denoted by the same reference numerals, and description thereof will be omitted.

In this circuit, a set of switch elements Q1, Q4 and switch elements Q2,
By alternately turning on and off the set of Q3, a high-frequency voltage is applied to the load circuit 1 and simultaneously the switching element Q2
The input current is drawn from the commercial AC power supply AC through the filter circuit F, the full-wave rectifier 12, and the chopper choke L3 during the on-period, and energy is stored in the chopper choke L3, and the chopper choke during the off-period of the switch element Q2. A boost chopper operation is performed to store the energy stored in L3 in the smoothing capacitor C0 via the diode D1 connected in anti-parallel to the switch element Q1. In the boost chopper circuit, if the ON period of the switching element Q2 is lengthened,
The energy stored in the choke choke L3 increases, the voltage across the smoothing capacitor C0 increases, and if the on-period of the switch element Q1 is shortened, the energy stored in the choke choke L3 decreases, resulting in smoothing. The voltage across the capacitor C0 decreases.

Therefore, the on-duty ratio control circuit 13 controls the on-duty ratio of the switching element Q2 according to each operation mode of the discharge lamp FL, thereby controlling the voltage across the smoothing capacitor C0 to a desired voltage value. Can be. Thus, the on-duty ratio of the switching element Q2 changes according to the operation mode of the discharge lamp FL, and the switching element Q2
1 and Q2, the on-duty ratios become unequal, so that even if the discharge lamp FL is normal, the DC cut capacitor C
Although the DC component superimposed on the reference voltage Vc changes, the reference voltage generator 11a changes the reference voltage Vr according to the change in the on-duty ratio.
Is changed, the life detection circuit 11 does not erroneously detect the change in the DC component due to the change in the on-duty ratio as the end-of-life state of the discharge lamp FL, and can accurately detect the end-of-life state.

In this embodiment, the switching element Q2 is shared by the full-bridge inverter circuit and the step-up chopper circuit. However, the switching element Q2 is not limited to the above-described circuit configuration. The circuit may be configured so that either one is used as both the full-bridge inverter circuit and the chopper circuit, and the chopper circuit performs the chopper operation, thereby reducing the harmonic distortion of the input current.

(Embodiment 3) FIG. 5 is a circuit diagram showing a discharge lamp lighting device according to this embodiment. In the discharge lamp lighting device according to the second embodiment, one switch element Q2 is shared by the full-bridge inverter circuit and the boost chopper circuit.
In the present embodiment, two switch elements Q1 and Q2 are shared by the full-bridge inverter circuit and the boost chopper circuit. Note that the same components as those of the discharge lamp lighting device according to the first or second embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In this circuit, a series circuit of diodes D5 and D6 serving as fifth and sixth rectifiers is connected in anti-parallel with a series circuit of switch elements Q1 and Q2.
At the connection point of Q2, choke (inductor) L3 for chopper
Is connected, and a commercial AC power supply AC is connected via a filter circuit F between the other end of the chopper choke L3 and the connection point of the diodes D5 and D6.

Here, during a period in which the side of the commercial AC power supply AC connected to the chopper choke L3 via the filter circuit F is positive, the switch element Q2 is also used as a switch element of the boost chopper circuit. That is, during the ON period of the switch element Q2, the input current is drawn through the path of the commercial AC power supply AC → the filter circuit F → the choke L3 for the chopper → the switch element Q2 → the diode D6 → the filter circuit F → the commercial AC power supply AC. Energy is accumulated in the choke L3, and a boosting chopper operation is performed in which the energy accumulated in the choke choke L3 during the OFF period of the switch element Q2 is accumulated in the smoothing capacitor C0 via the diode D1 connected in anti-parallel to the switch element Q1. .
On the other hand, during a period in which the side of the commercial AC power supply AC connected to the connection point of the diodes D5 and D6 via the filter circuit F is positive, the switch element Q1 is also used as a switch element of the boost chopper circuit. That is, the switching element Q1
AC power supply AC → Filter circuit F → Diode D5 → Switching element Q1 → Chopper choke L during the ON period of
3 → the filter circuit F → the input current is drawn in the path of the commercial AC power supply AC, energy is accumulated in the choke choke L3, and the energy accumulated in the chopper choke L3 during the OFF period of the switch element Q1 is converted to the switch element Q2.
Performs a step-up chopper operation of accumulating in the smoothing capacitor C0 via the diode D2 connected in anti-parallel to suppress harmonic distortion included in the input current.

In this circuit, instead of using the full-wave rectifier 12 composed of a diode bridge, the switching elements Q1,
A series circuit of diodes D5 and D6 is connected in anti-parallel with the series circuit of Q2, and a full-wave rectifier can be configured by simply adding two diodes D5 and D6, reducing the number of circuit components and reducing costs. And a circuit in which harmonic distortion of the input current is reduced at low cost can be realized.

Here, if the ON period of the switching elements Q1 and Q2 is lengthened, the energy stored in the choke L3 for chopper increases, the voltage across the smoothing capacitor C0 increases, and the ON state of the switching elements Q1 and Q2 increases. If the period is shortened, the energy stored in the choke choke L3 decreases, and the voltage across the smoothing capacitor C0 decreases. Therefore, the on-duty ratio control circuit 13 switches the switch element in accordance with each operation mode of the discharge lamp FL. By controlling the on-duty ratio of Q1 and Q2, the voltage across smoothing capacitor C0 can be controlled to a desired voltage value. Thus, the switching elements Q1, Q2 are selected according to the operation mode of the discharge lamp FL.
2, the on-duty ratio changes, and the switching elements Q1, Q
2 are not equal, the discharge lamp F
Even if L is normal, the DC component superimposed on the DC cut capacitor Cc changes, but the reference voltage generator 11a
Changes the reference voltage Vr in accordance with the change in the on-duty ratio. Therefore, similarly to the second embodiment, the end-of-life detection circuit 11 detects the change in the DC component due to the change in the on-duty ratio in the end-of-life state of the discharge lamp FL. Is not erroneously detected as
The end-of-life state of the discharge lamp FL can be accurately detected.

In this circuit, the switching elements Q1, Q
Although the commercial AC power supply AC is connected via the choke L3 for the chopper between the connection point of the switching element Q2 and the connection point of the diodes D5 and D6, the connection point of the switching elements Q3 and Q4 and the connection point of the diodes D5 and D6. Choke L for chopper between
3, the commercial AC power supply AC may be connected, and the same effect as described above can be obtained.

(Embodiment 4) FIG. 6 is a circuit diagram showing a discharge lamp lighting device according to this embodiment. In this circuit, in the discharge lamp lighting device according to the first embodiment, instead of connecting a series circuit of the capacitors C1 and C2 in parallel with the discharge lamp FL, a capacitor as a fifth impedance element that forms a resonance circuit together with the inductors L1 and L2 C5 is connected in parallel with the discharge lamp FL. Further, a voltage detecting resistor R as third and fourth impedance elements is provided in parallel with the discharge lamp FL.
1 and R2, a resistor R3 is connected between the connection point of the resistors R1 and R2 and the negative electrode of the DC power supply VDC, and the voltage across the resistor R3 and the reference voltage V of the reference voltage generator 11a.
and r is compared by the comparator CP1. Here, the inductance values of the inductors L1 and L2 are set to substantially equal values, and the resistance values of the resistors R1 and R2 are set to substantially equal values. Note that the same components as those of the discharge lamp lighting device of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Also in this embodiment, the DC power supply VDC may be configured by a boost chopper circuit as described in the second or third embodiment.

The life detecting circuit 11 detects the voltage Va at the connection point between the resistors R1 and R2 from the voltage across the resistor R3.
During normal lighting of the discharge lamp FL, the voltage V across the discharge lamp FL
1 and V2 are high-frequency AC voltages having the same amplitude and opposite phases with respect to VDC / 2, so that the voltage Va at the connection point of the resistors R1 and R2 has the high-frequency components offset each other, and (V
DC / 2) × R3 (R1 + R2) / (R1R2 + R2R
3 + R3R1) and the comparator CP1
Compares the voltage Va with the reference voltage Vr, and outputs the comparison result to the control circuit 10.

Here, when the reference voltage Vr is set to the voltage value of the voltage Va when the discharge lamp FL is normally lit, the comparison result between the voltage Va and the reference voltage Vr becomes zero when the discharge lamp FL is lit normally. On the other hand, when the discharge lamp FL enters the Emiless state at the end of its life and the discharge lamp FL starts half-wave discharge, the DC component superimposed on the voltages V1 and V2 between both ends increases, and the voltage Va increases. Voltage V
Since the comparison result between a and the reference voltage Vr is not zero, the control circuit 10 can detect the end-of-life state of the discharge lamp FL from the comparison result of the comparator CP1.

In this embodiment, the third and fourth impedance elements and the life detecting means are constituted by the resistors R1 to R3. However, the third and fourth impedance elements and the life detecting means are limited to the resistors. Instead, it may be constituted by impedance elements Z1 to Z3 such as capacitors (see FIG. 7). At this time, when the discharge lamp FL is normally lit, the voltages V1 and V2 across the discharge lamp FL are equal to VDC.
Since the high-frequency AC voltages have the same amplitude in opposite phases with respect to / 2, the high-frequency components of the potential Va at the connection point of the impedance elements Z1 and Z2 cancel each other and (VD
C / 2) × ｛Z3 (Z1 + Z2) / (Z1Z2 + Z2Z
3 + Z3Z1) DC voltage. Therefore, if the reference voltage Vr is set to the voltage value of the voltage Va at the time of normal lighting, when the discharge lamp FL enters the emiless state at the end of its life and the discharge lamp FL starts half-wave discharge, the voltage V1 across the discharge lamp FL , V2 increases, and the voltage Va and the reference voltage Vr become unequal. Therefore, the control circuit 10 determines the discharge lamp FL from the comparison result of the comparator CP1.
The end-of-life state can be accurately detected.

(Embodiment 5) FIG. 8 is a circuit diagram of a discharge lamp lighting device according to this embodiment. In the first embodiment, a capacitor C3 is connected between a connection point of the capacitors C1 and C2 connected between both ends of the discharge lamp FL and a negative electrode of the DC power supply VDC,
Although the potential Va at the connection point between the capacitors C1 and C2 is detected from the voltage across the capacitor C3, in the present embodiment,
A current transformer CT in which a primary winding is connected between a connection point of the capacitors C1 and C2 and a negative electrode of the DC power supply VDC, and an intermediate tap of a secondary winding is connected to the negative electrode of the DC power supply VDC; D9 and D11 each having an anode connected to both ends of the secondary winding of
And the cathodes of the diodes D9 and D11 and the DC power supply VD
A life detecting circuit including a capacitor C3 connected between the negative electrode of C, a reference voltage generator 11a for generating a reference voltage Vr, and a comparator CP1 for comparing the voltage Vc across the capacitor C3 with the reference voltage Vr. The current Ia flowing on the primary side of the current transformer CT is converted into a voltage Vc by the current transformer CT and the diodes D9 and D11 and detected. Note that the same components as those of the discharge lamp lighting device of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Also, in the present embodiment, as described in the second or third embodiment, the DC power supply VD
C may be configured by a step-up chopper circuit.

FIGS. 9A and 9B show the current Ia and the voltage Vc when the discharge lamp FL is normally lit and when it is abnormally lit. At the time of normal lighting of the discharge lamp FL, the current Ia flowing to the primary side of the current transformer CT becomes substantially zero, so that the voltage Vc also becomes substantially zero. On the other hand, when the discharge lamp FL enters the Emiless state at the end of its life and is abnormally lit such that the discharge lamp FL starts half-wave discharge, the symmetry of the voltage V1, V2 between the both ends of the discharge lamp FL is broken, and the current transformer CT Flows on the primary side of the capacitor C3, and the voltage Ic across the capacitor C3 increases due to the current Ia. If the reference voltage Vr is set to a value lower than the voltage Vc at the time of abnormal lighting, the voltage Vc becomes higher than the reference voltage Vr and the output of the comparator CP1 is inverted at the time of abnormal lighting. The end-of-life state of the discharge lamp FL can be detected from the comparison result of the comparator CP1.

In each of the above embodiments, the discharge lamp FL has an optical path length of, for example, about 1400 mm or more and about 2
500mm or less, tube diameter is about 18mm or more and about 29m
m or less may be used. It is needless to say that the discharge lamp FL is not limited to the above-described one, but may be one having a desired optical path length or tube diameter.

(Embodiment 6) FIG. 10 is a circuit diagram of a discharge lamp lighting device according to this embodiment. In the present embodiment, the fluorescent lamp FL ′ having the filament electrodes f1 and f2 is used as the discharge lamp load in the discharge lamp lighting device of the first embodiment. In this circuit, the power supply side terminal of one filament electrode f1 of the fluorescent lamp FL 'is connected to the connection point A of the switching elements Q1 and Q2 via the inductor L1, and the power supply terminal of the other filament electrode f2 of the fluorescent lamp FL' is connected. The side terminal is connected to a connection point B of the switching elements Q3 and Q4 via a series circuit of a DC cut capacitor Cc and an inductor L2, and both filament electrodes f1 and f1 of the fluorescent lamp FL 'are connected.
A series circuit of capacitors C1 and C2 is connected between the non-power-supply-side terminals of f2. Here, a resonance circuit is formed by the capacitors C1 and C2 and the inductors L1 and L2, and the capacitors C1 and C2 are also used as capacitors for preheating the filament electrodes f1 and f2. Note that the same components as those of the discharge lamp lighting device of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Also, in the discharge lamp lighting devices according to the second to fifth embodiments, it is needless to say that the fluorescent lamp FL ′ having a filament electrode may be used as the discharge lamp load as in the present embodiment.

The life detecting circuit 11 has the same configuration as that of the first embodiment. When the fluorescent lamp FL 'enters the emiless state at the end of the life of the fluorescent lamp FL' and the fluorescent lamp FL 'starts half-wave discharge,
The DC component superimposed on the voltages V1 and V2 across the fluorescent lamp FL 'increases, and the voltage Va at the connection point of the capacitors C1 and C2 increases.
Increase. Here, since the reference voltage Vr is set to the voltage value of the voltage Va at the time of normal lighting, when the voltage Va increases at the end of the life, the comparison value between the voltage Va and the reference voltage Vr becomes non-zero, so that the control circuit At 10, the end-of-life state of the fluorescent lamp FL 'can be detected from the output of the comparator CP1.

When one of the filament electrodes f1 and f2 is disconnected, an AC voltage is generated at the connection point between the capacitors C1 and C2. Therefore, the life detecting circuit 11 is configured as shown in the fifth embodiment. Capacitor C
It is possible to detect an AC voltage generated at a connection point between the first and second electrodes C1 and C2, and it is also possible to detect a break in the filament electrodes f1 and f2. Further, in this circuit, since the capacitors C1 and C2 can be used for both preheating and detection, the number of circuit components can be reduced and the cost can be reduced.

Here, for example, a ring-shaped fluorescent lamp having a rated lamp output of about 97 W, a rated lamp current of about 0.43 A, and a rated lamp voltage of about 229 V may be used for the fluorescent lamp FL ′. A ring-shaped fluorescent lamp having 68 W, a rated lamp current of about 0.43 A, and a rated lamp voltage of about 160 V may be used. It is needless to say that the fluorescent lamp FL 'is not intended to be limited to the one described above, and that a fluorescent lamp having each rated value other than the above values may be used.

The discharge lamp lighting device of each of the above-described embodiments has a full-bridge circuit configuration in which switch elements Q1 to Q4 are bridge-connected, and is about twice as large as a half-bridge circuit configuration. Since this AC voltage can be applied to the load circuit, the circuit configuration is particularly suitable for high-frequency lighting of a high-voltage fluorescent lamp having a double thin tube. Also, in the case of a thin tube fluorescent lamp, there is a problem that the filament electrode becomes overheated at the end of life,
It is necessary to surely detect the end-of-life state to perform a protection operation, and in this respect, the discharge lamp lighting device of the present invention is a circuit configuration suitable as a lighting circuit of a thin tube fluorescent lamp.

In each of the above embodiments, the first to fourth
Although the switch elements Q1 to Q4 formed of bipolar transistors are used for the switch means of the above, the first to fourth switch means are not limited to bipolar transistors.
ET may be used. When a MOSFET having a body diode is used for the first to fourth switch means, the first to fourth rectifier means can be used also as the body diode of the MOSFET, thereby reducing the number of circuit components and reducing cost. Can be achieved.

[0051]

As described above, the first aspect of the present invention comprises a series circuit of first and second switch means connected between a positive electrode and a negative electrode of a DC power supply, and a series circuit of a positive electrode and a negative electrode of the DC power supply. A series circuit of third and fourth switch means connected therebetween;
First to fourth rectifiers connected in antiparallel with the first to fourth switch means, a first impedance element having one end connected to a connection point of the first and second switch means, A second impedance element having one end connected to a connection point of the third and fourth switch means, and a second impedance element connected via a capacitor between the other end of the first impedance element and the other end of the second impedance element; A load circuit including at least a discharge lamp, third and fourth impedance elements connected between both ends of the load circuit and forming a resonance circuit together with the first and second impedance elements; A control circuit that controls the on / off of the switch means to supply high-frequency AC power to the load circuit, and detects the end-of-life state of the discharge lamp from the amount of electricity at the connection point of the third and fourth impedance elements. A life detecting means, wherein the life detecting means detects an end-of-life state of the discharge lamp from an amount of electricity at a voltage dividing point obtained by dividing a voltage between both ends of the discharge lamp by third and fourth impedance elements. As a result, it is possible to directly detect the DC component superimposed during abnormal lighting, which has the effect of eliminating detection delays and detection errors that occur when detecting high-frequency components. Rectifies high frequency components compared to
Since a smoothing circuit is not required and the circuit configuration of the life detecting means is simplified, there is also an effect that cost can be reduced.

According to a second aspect of the present invention, there is provided a series circuit of first and second switch means connected between a positive electrode and a negative electrode of a DC power supply, and a series circuit connected between a positive electrode and a negative electrode of the DC power supply. 3
And a series circuit of fourth switch means, first to fourth rectifier means connected in antiparallel with the first to fourth switch means, respectively, and one end at a connection point of the first and second switch means. Is connected to a first impedance element,
And a second impedance element having one end connected to a connection point of the fourth switch means, and a second impedance element connected via a capacitor between the other end of the first impedance element and the other end of the second impedance element. A resonance circuit is formed together with a load circuit including at least a discharge lamp, third and fourth impedance elements connected between both ends of the load circuit, and the first and second impedance elements connected between both ends of the load circuit. A fifth impedance element, a control circuit that controls on / off of the first to fourth switch means to supply high-frequency AC power to the load circuit, And a life detecting means for detecting an end-of-life state of the discharge lamp, wherein the life detecting means detects the third and third end voltages of the discharge lamp. Since the end-of-life state of the discharge lamp is detected from the quantity of electricity at the voltage division point divided by the impedance element, the DC component superimposed at the time of abnormal lighting can be directly detected, and when the high frequency component is detected. This has the effect of eliminating detection delays and detection errors that occur, and eliminates the need for a circuit for rectifying and smoothing high-frequency components as compared with the case of detecting high-frequency components, thereby simplifying the circuit configuration of the life detecting means. Therefore, there is also an effect that the cost can be reduced.

According to a third aspect of the present invention, in the first or second aspect, the impedance of the first impedance element is substantially equal to the impedance of the second impedance element, and the first and second impedance elements are substantially equal. Since the impedance element is provided at both ends of the load circuit, there is an effect that fluctuation of the voltage between both ends of the discharge lamp due to switching of the first to fourth switch means can be eliminated.

According to a fourth aspect of the present invention, in the first or second aspect, the impedance of the third impedance element is substantially equal to the impedance of the fourth impedance element, and the connection of the third and fourth impedance elements is performed. Since the potential at the point is a voltage obtained by averaging the voltages at both ends of the discharge lamp, there is an effect that the high-frequency component is canceled and the DC component can be directly detected.

According to a fifth aspect of the present invention, in the first or second aspect of the invention, the life detecting means detects the end-of-life state of the discharge lamp from the DC component of the electric quantity at the connection point of the third and fourth impedance elements. Since the life detecting means directly detects the DC component, there is no need to provide a circuit for rectifying and smoothing the high frequency component as in the case of detecting the high frequency component. This has the effect that the detection delay and the detection error occurring in the above can be eliminated.

According to a sixth aspect of the present invention, in the first or second aspect of the present invention, the discharge lamp has a filament electrode at both ends, and is connected between the other end of the first impedance element and the other end of the second impedance element. A power supply side terminal of both filament electrodes is connected via a capacitor therebetween, and a series circuit of third and fourth impedance elements is connected between the non-power supply side terminals of both filament electrodes. It is.

According to a seventh aspect of the present invention, in the first to sixth aspects of the present invention, the DC power supply connects an AC power supply between AC input terminals of a full-wave rectifier, and includes a first to a fourth switching means. A DC output terminal of a full-wave rectifier is connected between both ends of any of the switch means via an inductor, and a smoothing capacitor is connected in parallel with a series circuit of the first and second switch means, A chopper circuit is composed of a full-wave rectifier, an inductor, a smoothing capacitor, a switch means, and a rectifier connected in anti-parallel to the switch means. By performing the chopper operation, harmonic distortion contained in the input current can be reduced. effective.

According to an eighth aspect of the present invention, in the first to sixth aspects of the present invention, the DC power supply is a series circuit of fifth and sixth rectifiers in anti-parallel with the series circuit of the first and second switch means. And an inductor is connected between one of the connection points of the first and second switch means or the connection point of the third and fourth switch means and the connection point of the fifth and sixth rectifier means. And a smoothing capacitor connected in parallel with the series circuit of the first and second switch means, the fifth and sixth rectifier means, an inductor, a smoothing capacitor, a switch means, A chopper circuit is constituted by rectifying means connected in anti-parallel to the switching means. By performing the chopper operation, there is an effect that harmonic distortion included in the input current can be reduced, and two rectifying means are provided. It is possible to configure the full-wave rectifier only by pressing, it is possible to reduce the number of components constituting the circuit as compared with the invention of claim 7, there is also an effect that costs can be reduced.

According to a ninth aspect of the present invention, in the first to eighth aspects, the discharge lamp has an optical path length of about 1400 mm or more and about 2500 mm or less, and a tube diameter of about 18 mm or more and about 29 mm or less. This is a desirable embodiment.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating a discharge lamp lighting device according to a first embodiment.

FIGS. 2 (a) to 2 (c) are waveform diagrams illustrating the operation of the above discharge lamp lighting device during normal lighting.

FIGS. 3 (a) to 3 (c) are waveform diagrams illustrating the operation of the above discharge lamp lighting device during abnormal lighting.

FIG. 4 is a circuit diagram showing a discharge lamp lighting device according to a second embodiment.

FIG. 5 is a circuit diagram illustrating a discharge lamp lighting device according to a third embodiment.

FIG. 6 is a circuit diagram illustrating a discharge lamp lighting device according to a fourth embodiment.

FIG. 7 is a circuit diagram showing another discharge lamp lighting device of the above.

FIG. 8 is a circuit diagram showing a discharge lamp lighting device according to a fifth embodiment.

FIGS. 9A and 9B are waveform diagrams illustrating the operation of the above.

FIG. 10 is a circuit diagram illustrating a discharge lamp lighting device according to a sixth embodiment.

FIG. 11 is a circuit diagram showing a conventional discharge lamp lighting device.

FIG. 12 is a circuit diagram showing another discharge lamp lighting device of the above.

FIG. 13 is a circuit diagram showing still another discharge lamp lighting device of the above.

[Explanation of symbols]

 11 Life detection circuit C1 to C3, Cc Capacitor FL Discharge lamp L1, L2 Inductor Q1 to Q4 Switch element Va voltage

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masato Onishi 1048 Odomo Kadoma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Works, Ltd. HB03

Claims (9)

[Claims] 1. A series circuit of first and second switch means connected between a positive electrode and a negative electrode of a DC power supply, and third and fourth series circuits connected between a positive electrode and a negative electrode of the DC power supply. One end is connected to a connection point of the series circuit of the switch means, the first to fourth rectification means connected in antiparallel with the first to fourth switch means, respectively, and the first and second switch means. A first impedance element, a second impedance element having one end connected to a connection point of the third and fourth switch means, and a second impedance element having the other end of the first impedance element and the other end of the second impedance element. A load circuit including at least a discharge lamp connected via a capacitor therebetween, and third and fourth impedance elements connected between both ends of the load circuit to form a resonance circuit together with the first and second impedance elements; , First A control circuit for controlling the on / off of the fourth switch means to supply high-frequency AC power to the load circuit, and a lifetime for detecting an end-of-life state of the discharge lamp from an electric quantity at a connection point of the third and fourth impedance elements. A discharge lamp lighting device comprising: a detection unit. 2. A series circuit of first and second switch means connected between a positive electrode and a negative electrode of a DC power supply, and a third and a fourth circuit connected between a positive electrode and a negative electrode of the DC power supply. One end is connected to a connection point of the series circuit of the switch means, the first to fourth rectification means connected in antiparallel with the first to fourth switch means, respectively, and the first and second switch means. A first impedance element, a second impedance element having one end connected to a connection point of the third and fourth switch means, and a second impedance element having the other end of the first impedance element and the other end of the second impedance element. A load circuit including at least a discharge lamp connected via a capacitor therebetween, third and fourth impedance elements connected between both ends of the load circuit, and the first and fourth elements connected between both ends of the load circuit. 2 impedance elements Fifth impedance element which together forms a resonance circuit, control circuit for controlling on / off of first to fourth switch means to supply high-frequency AC power to a load circuit, and connection of third and fourth impedance elements A discharge lamp lighting device comprising: a life detecting unit configured to detect an end-of-life state of the discharge lamp from a quantity of electricity at a point. 3. The discharge lamp lighting device according to claim 1, wherein impedances of the first impedance element and the second impedance element are substantially equal. 4. The discharge lamp lighting device according to claim 1, wherein the impedances of the third impedance element and the fourth impedance element are substantially equal. 5. The discharge lamp according to claim 1, wherein the life detecting means detects an end-of-life state of the discharge lamp from a DC component of an electric quantity at a connection point of the third and fourth impedance elements. Lighting device. 6. The discharge lamp has a filament electrode at both ends, and power supply terminals of both filament electrodes are connected between the other end of the first impedance element and the other end of the second impedance element via a capacitor. The discharge lamp lighting device according to claim 1, wherein a series circuit of the third and fourth impedance elements is connected between the non-power-supply-side terminals of the two filament electrodes. 7. The DC power supply according to claim 1, wherein the AC power supply is connected between AC input terminals of a full-wave rectifier, and is connected between both ends of any one of the first to fourth switch means via an inductor. Connecting the DC output terminals of the wave rectifier to the first and second
7. The discharge lamp lighting device according to claim 1, wherein a smoothing capacitor is connected in parallel with the series circuit of the switch means. 8. The DC power source connects a series circuit of fifth and sixth rectifiers in anti-parallel with a series circuit of first and second switch means, and connects the first and second switch means. An AC power source is connected via an inductor between the point or one of the connection points of the third and fourth switch means and the connection point of the fifth and sixth rectification means, and the first and second switches are connected. 7. The discharge lamp lighting device according to claim 1, wherein a smoothing capacitor is connected in parallel with the series circuit of the means. 9. The discharge lamp according to claim 1, wherein the discharge lamp has an optical path length of about 1400 mm or more and about 2500 mm or less, and a tube diameter of about 18 mm or more and about 29 mm or less.
The discharge lamp lighting device as described in the above.