JP3059517B2 - Discharge lamp lighting device - Google Patents

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 for lighting, for example, a high-pressure discharge lamp with a full-bridge inverter in a rectangular wave.

[0002]

2. Description of the Related Art FIG. 14 is a circuit diagram of a conventional discharge lamp lighting device of this type. In this discharge lamp lighting device, as shown in FIG. 14, first and second switching elements Q ₁ and Q ₂ are connected in series between a positive electrode and a negative electrode of a DC power supply _VDC in this order, and a DC power supply Third between _DC positive and negative electrodes
And the fourth switching elements Q ₃ , Q ₄ are connected in series in this order, and the first, second, third and fourth switching elements Q ₁ , Q ₂ , Q ₃ , Q ₄ are connected in series to the first, second, Third and fourth diodes D ₁ , D ₂ , D ₃ and D ₄ are connected in anti-parallel, respectively.

[0003] One end of a discharge lamp DL is connected to a connection point between the first and second switching elements Q ₁ and Q ₂ , and an inductor L is connected to a connection point between the third and fourth switching elements Q ₃ and Q _4. through ₀ connects the other end of the discharge lamp DL, are connected in parallel a capacitor C ₀ to the discharge lamp DL. Also, the potentials V _A and V _{B at} both ends of the discharge lamp DL.
(The difference voltage becomes a lamp voltage) and a potential detecting means (not shown) for detecting
And the fourth switching elements Q ₁ , Q ₂ , Q ₃ , Q ₄
There is provided control means (not shown) for controlling on / off of the power supply.

In the discharge lamp lighting device having the above-described configuration, the control means specifically turns on and off the first and fourth switching elements Q ₁ and Q _{4 at} a high frequency, and simultaneously sets the second and fourth switching elements Q ₁ and Q ₄ . 3 switching elements Q ₂ ,
The first state and the second and third switching element Q _2, the first and fourth switching elements Q _1, Q ₄ off causes repeated at off the high frequency Q ₃ which holds the Q ₃ off The held second state is alternately repeated at a low frequency.

Further, based on the detection result of the potential detecting means, the first, second, third and fourth switching elements Q
_The lamp voltage or lamp current is controlled by controlling the lengths of the ON period and the OFF period of ₁ , Q ₂ , Q ₃ , and Q ₄ . The above discharge lamp lighting device, both ends of the potential V _A of the discharge lamp DL, V _B, respectively Figure 15 (a), as shown in (b). In Figure 15, SW ₁ is first held in the second and third switching elements Q _2, Q ₃ off causes repeated at a high frequency on-off of the first and fourth switching elements Q _1, Q ₄ a period of state, SW ₂ is first held in the second and third switching element Q _2, the first and fourth switching elements Q _1, Q ₄ off causes repeated at off the high frequency Q ₃ This is the period of state 2.

[0006] V_DLIs the lamp voltage and the potential V_BIn
Period SW₁Then the lamp voltage V_DLIs superposed on the negative polarity and the period
SW_TwoThen the lamp voltage V_DLOverlap with the positive polarity. Above
A potential detector for detecting the potential at both ends of the discharge lamp DL.
As the output means, for example, a differential amplifier as shown in FIG.
DA_ThreeAnd the potential V at both ends of the discharge lamp DL is considered.
_A, V_BIs the DC power supply V_DCNegative side as ground
Force, the differential amplifier DA_ThreeOutput voltage V_O1As
Lamp voltage V as shown in FIG. _DLCan detect
Wear. In FIG. 17, the period SW₁Then the lamp voltage V
_DLBecomes positive polarity and the period SW_TwoIs now negative
You.

The differential amplifier DA shown in FIG._ThreeInstead of
And a diode D as shown in FIG. ₁₁, Resistance R₁₇And
And capacitor C_FourUsing a detection circuit DW consisting of
And the lamp voltage V_DLCan be detected. One
In other words, the detection circuit DW has the potential V_BIs the DC power supply V_DCof
Half-wave rectification and integration with the negative side as ground
And the resistance R₁₇And capacitor C_FourTime constant of
Period SW₁And period SW_TwoLarge enough compared to the switching cycle
Output voltage V_O2As shown in FIG.
Voltage is obtained. Note that this voltage V_O2The peak value of V
_DC+ V_DLBecomes However, the DC power supply voltage V_DCIs constant
You.

[0008]

The circuit shown in FIG.
In the first conventional example of combining the differential amplifier DA ₃ of
Although the difference between the potential V _A and the potential V _B is the lamp voltage V _DL, the potential V _A, the power supply voltage which is chopped at a switching frequency in each of the V _B are superposed as common mode. To calculate such a difference in signal potential, differential amplifier DA ₃ used. However, the differential amplifier DA ₃ has a property that ability to remove common-mode decreases as the frequency of the common mode is high. Therefore, it superimposed common mode output of the differential amplifier DA _3, for its removal, is necessary to add an integration circuit occurs.

The circuit shown in FIG. 14 has a detection circuit D shown in FIG.
In the second conventional example in which W is combined, since a half-period voltage is generated by the integration circuit, it must have a sufficiently long time constant with respect to the switching period. in this way,
It becomes necessary to insert an integrating circuit into the detection circuit for the lamp voltage _VDL . However, if the time constant of the integration circuit is long, there is a problem in that a time lag occurs in detection with respect to the actual state of the discharge lamp DL, so that control according to the state of the discharge lamp DL cannot be performed.

Accordingly, it is an object of the present invention to provide a discharge lamp lighting device capable of detecting a lamp voltage of a discharge lamp at a high speed.

[0011]

As shown in FIG. 1, a discharge lamp lighting device according to the present invention comprises first and second switching elements Q ₁ and Q ₂ between a positive electrode and a negative electrode of a DC power supply _VDC. together with connected in series in this order, DC power source V _DC positive electrode and the third and fourth switching elements Q ₃ between the negative electrode,
They are connected in series to Q ₄ in this order. Then, one end of a discharge lamp DL is connected to a connection point between the first and second switching elements Q ₁ and Q ₂ via a _first inductor L ₁ ,
The other end of the discharge lamp DL is connected to a connection point of the third and fourth switching elements Q ₃ and Q ₄ via a _second inductor L ₂ having an inductance value substantially equal to that of the first inductor L _1. A capacitor C ₀ is connected in parallel to DL.

Further, the electric potential V _A at both ends of the discharge lamp DL,
Potential detection means for detecting the V _B (not shown) is provided, first
And a first state in which the on and off of the fourth switching elements Q ₁ and Q ₄ are repeated and the second and third switching elements Q ₂ and Q ₃ are kept off, and the second and third switching elements Q ₂ and Q ₃ are repeatedly turned on and off, and the first and fourth switching elements Q
_1, Q ₄ were alternately repeated and a second state for holding off the first on the basis of the detection result of the potential detection means, the second,
Third and fourth switching elements Q ₁ , Q ₂ , Q ₃ ,
Control means for controlling the length of the ON period and the OFF period of the Q ₄ are provided.

D _{1 to} D ₄ are switching elements Q _{1 to} Q ₄
Is connected in anti-parallel to the diode. Note that the first and second inductors L ₁ and L ₂ have a common iron core,
They may be independent or either.

[0014]

According to the structure of the present invention, since the first and second inductors L ₁ and L ₂ having substantially equal inductance values are provided on both sides of the discharge lamp DL, the first to fourth switching elements Q _{1 to} Q 1 are provided. The fluctuation of the potential at both ends of the discharge lamp DL due to the high frequency switching of ₄ is eliminated. Therefore, an integration circuit for suppressing voltage fluctuation is not required, and detection delay due to integration is eliminated. As a result, the lamp voltage of the discharge lamp DL can be detected at high speed.
On / off of the _{first to fourth} switching elements Q _{1 to} Q ₄ can be controlled in accordance with the change in the state of L.

[0015]

【Example】

 (First Embodiment) A first embodiment of the present invention will be described with reference to FIGS.
A description will be given based on FIG. This discharge lamp lighting device is shown in FIG.
As shown in FIG. 3, one end of the discharge lamp DL is connected to the first and second discharge lamps DL.
Switching element Q₁, Q_TwoAt the connection point of
Kuta L₁And the other end of the discharge lamp DL is connected to the third
And the fourth switching element Q_Three, Q_FourAt the connection point
2 inductor L_TwoConnected through. First and
Second inductor L₁, L _TwoIs the inductance value etc.
And the series combined inductance value is
Inductor L₀Is set to the same as

The potential V at both ends of the discharge lamp DL is_A,
V_BIs the diode D_Five, D₆And resistance R₁Consisting of
Large value detection circuit MX₁At the potential V_A, V_BThe largest of
Value is output voltage V_O3Is output as In this case, the discharge lamp
The first and second inductors having substantially equal inductance values are provided on both sides of the pump DL.
And the second inductor L₁, L_TwoNo first
And the fourth switching element Q ₁~ Q_FourHigh frequency switch
Potential V across the discharge lamp DL_A, V_Bof
The fluctuation disappears. Therefore, the integration circuit for suppressing voltage fluctuation
No path is required, and detection delay due to integration is eliminated. this
As a result, the lamp voltage of the discharge lamp DL can be adjusted with high accuracy and high speed.
Can be detected and can be changed according to the state change of the discharge lamp DL.
And the first to fourth switching elements Q₁, Q_Two,
Q_Three, Q_FourCan be controlled, for example,
It can suppress fluctuations of pump voltage, lamp current, etc.
You.

In addition, the circuit configuration includes diodes D ₅ and D _5
6 and only uses the maximum value detecting circuit MX ₁ comprising resistors R _1, it is possible to perform voltage detection with an extremely simple circuit. In addition, as shown in FIG.
(Consisting of first to fourth switching elements Q ₁ to Q ₄₎
Even if two cables from the lamp to the discharge lamp DL cause a ground fault, since the inductors L ₁ and L ₂ are inserted in the cables on both sides, the current is limited by the inductors L ₁ and L ₂ and the switching element is switched. Q _{1 to} Q ₄ are not destroyed.

FIG. 3 shows the maximum value of the discharge lamp lighting device of FIG.
Value detection circuit MX₁(A) shows the input / output voltage of
Potential V_AAnd (b) shows the potential V_BAnd (c) is the voltage V_O3To
Each is shown. As is apparent from FIG.
_AIs the period SW₁Then (V_DC+ V_DL) / 2
SW_TwoThen (V_DC-V_DL) / 2. Further, the potential V _B
Is the period SW₁Then (V_DC-V_DL) / 2 and the period S
W_TwoThen (V_DC+ V_DL) / 2. Therefore, the maximum
Value detection circuit MX₁Is the potential V_A, V_BOutput the maximum value of
Therefore, always (V_DC+ V_DL) / 2.

[0019] FIG. 4 is caused by a change in the lamp voltage V _DL voltage V
FIG. 4 is a characteristic diagram showing a change in _O3 , where V _{DL 0} is a no-load lamp voltage. (Second Embodiment) A second embodiment of the present invention will be described with reference to FIGS. This discharge lamp lighting device is shown in FIG.
Instead of the maximum value detecting circuit MX ₁ in a diode D
₇ , a minimum value detection circuit MI ₁ composed of D ₈ and a resistor R _2.
The other configuration is the same as that of the discharge lamp lighting device of FIG.

In this embodiment, similarly to the first embodiment, the lamp voltage can be detected with high accuracy and high speed without the need for an integrating circuit for suppressing voltage fluctuation. Therefore,
On / off of the first to fourth switching elements Q ₁ , Q ₂ , Q ₃ , Q ₄ can be controlled in accordance with the state change of the discharge lamp DL, and for example, fluctuations in lamp voltage, lamp current, etc. are suppressed. be able to.

Further, the circuit configuration is composed of diodes D ₇ and D
₈ and the minimum value detecting circuit MI ₁ including a resistor R ₂ only uses, can be performed very simply voltage detection. Output voltage V _O4 of the minimum value detecting circuit MI ₁ in this embodiment, since outputs the minimum value of the potential V _A, V _B, always becomes _{(V DC -V DL) / 2} .

[0022] FIG. 6 is caused by a change in the lamp voltage V _DL voltage V
FIG. 4 is a characteristic diagram showing a change in _O4 . Third Embodiment A third embodiment of the present invention will be described with reference to FIGS. This discharge lamp lighting device is shown in FIG.
Instead of the maximum value detecting circuit MX ₁ of those using a differential amplifier DA _1, other configurations are the same as the discharge lamp lighting device of FIG.

Also in this embodiment, the first and second switching elements Q ₁ , Q ₂ , Q ₂ are provided on both sides of the discharge lamp DL because the first and second inductors L ₁ , L ₂ having substantially equal inductance values are provided. _3, Q ₄ of the high frequency across the potential V _a of the switching by the discharge lamp DL, the variation of V _B is eliminated. Therefore, unlike the first conventional example, voltage detection can be performed with high accuracy and high speed without requiring a differential amplifier having a high common-mode component removal function or without requiring an integrating circuit.

Further, even if the wiring leading to the discharge lamp DL is drawn from the inverter IV, the occurrence of common mode noise is small. Other effects are the same as those of the above-described embodiments. (Fourth Embodiment) A fourth embodiment of the present invention will be described with reference to FIG. This discharge lamp lighting device includes a discharge lamp DL
Both ends of the potential V _A of, rather than adding the V _B into direct differential amplifier DA ₁ shown in FIG. 7, the average value circuit consisting of resistors R ₃ and capacitor C _1, than the resistance R ₄ and the capacitor C ₂ Potentials V _A , V _B
Mean value V _A ', V _B' sought after, the differential amplifier D of
It is input to the A _2. In this case, the time constant of the resistor R ₃ and the capacitor C ₁ and the resistor R ₄ and the capacitor C 1
The time constant of ₂ is set sufficiently larger than the respective period SW _1, SW ₂ of the switching period. Others are the same as FIG.

The above-described configuration, the average value V _A 'and the potential V mean V _B of _B' is V _DC Both the potential V _A
/ 2, so that the output voltage V of the differential amplifier DA ₂ is normally
_O6 is zero. However, as shown in FIG. 13, if one power line extending from the inverter IV to the discharge lamp DL is grounded, since rather than _{V A '= V B' =} V DC / 2, the voltage V _O6 some A voltage is output. Thereby, an abnormality of inverter IV can be detected.

The other constitutional effects are the same as those of the prior art. (Fifth Embodiment) A fifth embodiment of the present invention will be described with reference to FIGS. This discharge lamp lighting device,
Instead of the maximum value circuit MX ₁ in FIG. 2, but using the maximum value circuit MX ₂ including a resistive attenuation circuit, other configurations 2
Is the same as

This maximum value circuit MX_TwoIs the voltage dividing resistor R_Five,
R₆, R₇, R₈And transistor Q _Five, Q₆, Q₇When,
Load resistance R₉, R_TenAnd a voltage dividing resistor R_Five, R₇Is
The resistance value is equal and the voltage dividing resistor R₆, R₈Are equal in resistance
No. This maximum value circuit MX_TwoIs the potential V_AThe voltage divider resistor
R_Five, R₆And the potential V_BIs the voltage dividing resistor R₇, R₈so
NPN-type transistor that divides voltage and also serves as current amplification
Q_Five, Q₆Select the maximum value of both divided voltages with
TA Q_Five, Q₆PNP transistor Q of opposite conductivity type
₇Output voltage V through the emitter follower_O7Take out
ing. Note that V_CCIs the control power supply voltage, V_O7≤V_CCIn
You.

The reason for the above configuration is as follows. In general, a control circuit that uses a detected voltage uses a considerably lower voltage than an inverter circuit. Therefore, it is usual that the potentials V _A and V _B are not detected as they are but are attenuated. As outputting a maximum value by inserting an attenuator, as shown in FIG. 11, simply dividing resistor R ₅ to the maximum value circuit MX ₁ in FIG. 2,
But R _6, R _7, the maximum value only by adding the R ₈ circuit MX ₃ is considered, in this circuit, the influence of the load resistor R _9,
Attenuation factor _{R 2 / (R 1 + R} 2) a can not be maintained accurately.

[0029] Therefore, as in the circuit shown in FIG. 10, in place of the diode D _9, D _10, NPN which also serves as a current amplification
Configured using the transistor Q _5, Q ₆ of the mold, while accurately maintaining the attenuation rate without being affected by the load resistor R _9, transistor Q _5, PNP type opposite conductivity type Q ₆ transistor Q ₇ and providing an emitter follower circuit consisting of the load resistors R _10, and so as to compensate for the temperature characteristics of the transistor Q _5, Q _6.

In this embodiment, the maximum value can be detected in a state where the potentials V _A and V _B at both ends of the discharge lamp DL are attenuated, and the decay rate can be maintained accurately, and the temperature change can be maintained. Can be eliminated. Other effects are similar to those of the first embodiment. (Sixth Embodiment) A sixth embodiment of the present invention will be described with reference to FIG. The discharge lamp lighting apparatus, instead of the minimum value circuit MI ₁ in FIG. 5, a maximum value circuit M which includes a resistor attenuating circuit
The other configuration is the same as that of FIG. 5 using I ₂ .

This minimum value circuit MI_TwoIs the voltage dividing resistor R₁₁,
R₁₂, R₁₃, R₁₄And transistor Q ₈, Q₉, Q_TenWhen,
Load resistance R₁₅, R₁₆And a voltage dividing resistor R₁₁, R₁₃Is
The resistance value is equal and the voltage dividing resistor R₁₂, R₁₄Are equal in resistance
No. This minimum value circuit MI_TwoIs the potential V_AThe voltage divider resistor
R₁₁, R₁₂And the potential V_BIs the voltage dividing resistor R₁₃, R₁₄so
PNP transistor that divides voltage and also serves as current amplification
Q₈, Q₉Select the minimum value of both divided voltages with
TA Q₈, Q₉NPN transistor Q of opposite conductivity type
_TenOutput voltage V through the emitter follower_O8Take out
ing. Note that V_CCIs the control power supply voltage, V_O8≤V_CCIn
You.

This minimum value circuit MI_TwoAlso serves as current amplification
NPN transistor Q_Five, Q ₆Configure using
And the damping rate is determined by the load resistance R₉Accurately maintained without being affected by
And the transistor Q_Five, Q₆Of the opposite conductivity type
PNP transistor Q₇And load resistance R_TenConsists of
By providing an emitter follower circuit, the transistor Q_Five, Q
₆Is compensated for.

In this embodiment, the minimum value can be detected in a state where the potentials V _A and V _B at both ends of the discharge lamp DL are attenuated, and the attenuation rate can be maintained accurately, and the temperature change can be maintained. Can be eliminated. Note that the inductors L ₁ and L _{2 in} each of the above embodiments may be either wound with the same iron core or wound with separate iron cores.

[0034]

According to the discharge lamp lighting apparatus of the present invention, since the first and second inductors having substantially equal inductance values are provided on both sides of the discharge lamp, high-frequency switching of the first to fourth switching elements is performed. Fluctuations in the potential at both ends of the discharge lamp can be eliminated. Therefore, an integration circuit for suppressing voltage fluctuation is not required, and detection delay due to integration is eliminated. As a result, the lamp voltage of the discharge lamp can be detected at high speed, and the on / off of the first to fourth switching elements can be controlled in accordance with a change in the state of the discharge lamp.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a discharge lamp lighting device according to the present invention.

FIG. 2 is a circuit diagram of the discharge lamp lighting device according to the first embodiment of the present invention.

FIG. 3 is a time chart of each unit in FIG. 2;

FIG. 4 is a characteristic diagram showing a change in voltage V _O3 with respect to a change in lamp voltage V _DL in the circuit of FIG. 2;

FIG. 5 is a circuit diagram showing a configuration of a main part of a discharge lamp lighting device according to a second embodiment of the present invention.

FIG. 6 is a characteristic diagram showing a change in voltage V _O3 with respect to a change in lamp voltage V _DL in the circuit of FIG. 5;

FIG. 7 is a circuit diagram showing a configuration of a main part of a discharge lamp lighting device according to a third embodiment of the present invention.

FIG. 8 is a time chart of an output voltage of the circuit of FIG. 7;

FIG. 9 is a circuit diagram showing a configuration of a main part of a discharge lamp lighting device according to a fourth embodiment of the present invention.

FIG. 10 is a circuit diagram showing a configuration of a main part of a discharge lamp lighting device according to a fifth embodiment of the present invention.

FIG. 11 is a circuit diagram of a reference maximum value circuit.

FIG. 12 is a circuit diagram showing a configuration of a main part of a discharge lamp lighting device according to a sixth embodiment of the present invention.

FIG. 13 is a schematic diagram showing a state of a ground fault of the discharge lamp lighting device.

FIG. 14 is a circuit diagram showing a conventional example of a discharge lamp lighting device.

FIG. 15 is a time chart of each part of the circuit of FIG. 14;

FIG. 16 is a circuit diagram of a portion for detecting a voltage across the discharge lamp.

17 is a time chart of the output voltage of the circuit of FIG.

FIG. 18 is a circuit diagram of a portion for detecting a voltage across the discharge lamp.

FIG. 19 is a time chart of the output voltage of the circuit of FIG. 18;

[Explanation of symbols]

V _DC DC power supply Q ₁ first switching element Q ₂ second switching element Q ₃ the third switching element Q ₄ fourth switching element DL discharge lamp C ₀ capacitor L ₁ first inductor L ₂ second inductor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H02M 7/48 H02M 7/5387 H05B 41/24 H02M 1/00

Claims (1)

(57) [Claims] A first and a second switching element are connected in series between a positive electrode and a negative electrode of a DC power supply in this order, and a third and a fourth switching element are connected between the positive and negative electrodes of the DC power supply. Connected in series in this order, the first and second
One end of the discharge lamp is connected to the connection point of the switching element through a first inductor, and the second inductor having an inductance value substantially equal to that of the first inductor is connected to the connection point of the third and fourth switching elements. The other end of the discharge lamp is connected to the discharge lamp, a capacitor is connected in parallel to the discharge lamp, and potential detecting means for detecting a potential at both ends of the discharge lamp is provided, and the first and fourth switching elements are turned on and off. The first state in which the second and third switching elements are kept off and the on / off of the second and third switching elements are repeated, and the first and fourth switching elements are kept off. The second state is alternately repeated with the first, second, third and fourth states based on the detection result of the potential detecting means. The discharge lamp lighting apparatus provided with control means for controlling the length of the ON period and OFF period of the switching element.