JPH11135283A - Discharge lamp lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce stress loaded on a circuit element constituting a control power circuit and supply stable control power voltage, by controlling one of positive and negative amplitudes of an alternating output voltage of an inverter circuit so as to be decreased when control power is higher than a given value, and by setting the decreased side voltage of positive and negative voltages of the output voltage to be the control power. SOLUTION: By changing on-duty of signal voltages Ho, Lo input from a control circuit 1 into switching elements Q1 , Q2 , output voltage of a control power circuit can be changed. For example, in a starting mode where high frequency voltage generated in a transformer T1 is high, when high frequency voltage with a low positive side peak is generated on the both sides of the transformer T1 as an unbalanced wave form where on-duty of the Ho of on- duties signal voltages Ho, Lo is larger, stress loaded on a circuit element can be reduced because the output voltage of a control power circuit becomes lower.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a discharge lamp lighting device.

[0002]

2. Description of the Related Art FIG. 6 shows a circuit diagram of a conventional example according to the present invention.

This circuit comprises an AC power supply Vs and a full-wave rectifier D
B, a series circuit of a smoothing capacitor C1 connected to the output terminal of the full-wave rectifier DB, and two transistors (hereinafter referred to as switching elements) Q1 and Q2 connected to both ends of the smoothing capacitor C1; A separately-excited inverter circuit including diodes D1 and D2 connected in anti-parallel to both ends of each of the switching elements Q1 and Q2,
A capacitor C3 connected in parallel with the inductor L1 and the primary winding n1 of the transformer T1 and the primary winding n1 of the transformer T1 connected between the output terminals A and B of the inverter circuit via a DC cut capacitor C2. , A discharge lamp La connected to both ends of the secondary winding n2 of the transformer T1, and a non-power-supply-side terminal of the discharge lamp La to form a preheating current conduction path for the discharge lamp La. It comprises a capacitor C4, a control circuit 1 for driving the switching elements Q1 and Q2, and a series circuit of a diode D3, a resistor R1, and an electrolytic capacitor C5 connected to both ends of a tertiary winding n3 of a transformer T1. Electrolytic capacitor C5
Is connected between the Vcc input terminals of the control circuit 1 and supplies control power to the control circuit 1. Here, the control circuit 1 changes the on-duty of the switching elements Q1 and Q2.

Next, the operation will be briefly described. Control circuit 1
As a result, the switching elements Q1 and Q2 are turned on and off alternately to convert the DC voltage into an AC high frequency voltage, and a rectangular high frequency voltage is generated between the output terminals A and B. This high-frequency voltage is applied across the discharge lamp La connected to the secondary side of the transformer T1 via the lighting resonance circuit, and the discharge lamp La is turned on. When the discharge lamp La is turned on,
The resonance condition of the inductor L1 and the capacitor C3 is broken, and the lamp voltage determined by the inductor L1 is applied to the discharge lamp La. That is, a lamp current determined by the inductor L1 is supplied to the discharge lamp La.

[0005]

However, in the above conventional example, the following problems occur.

[0006] From the control circuit 1, switching elements Q1, Q
Regardless of whether the on-duty of the signal voltage supplied to 2 is unbalanced or balanced, the on-duty is controlled to be constant in any of the preheating mode, the starting mode, and the lighting mode. Therefore, when the sinusoidal high-frequency voltage generated on the primary side of the transformer T1 changes in each mode of the preheating mode / starting mode / lighting mode, or due to a change in the ambient temperature or a change in the power supply voltage,
The high-frequency voltage generated in the tertiary winding n3 of the transformer T1 changes. In particular, when the high-frequency voltage generated on the primary side of the transformer T1 is very high as in the start mode, the high-frequency voltage generated on the tertiary winding n3 of the transformer T1 becomes very high, and the diode D3 and the resistor R1 In addition, the voltage supplied to the control power supply circuit including the smoothing capacitor C5 becomes excessive, and a large stress is generated in the circuit elements constituting the control power supply circuit. When the high frequency voltage generated on the primary side of the transformer T1 is low as in the lighting mode,
The high-frequency voltage generated in the tertiary winding n3 of the transformer T1 becomes low, and the voltage supplied to the control power supply circuit becomes insufficient. That is, it becomes difficult to supply a stable control power supply voltage.

[0007] The present invention has been made in view of the above problems, and an object of the present invention is to reduce stress applied to circuit elements constituting a control power supply circuit,
An object of the present invention is to provide a discharge lamp lighting device capable of supplying a stable control power supply voltage.

[0008]

According to the first aspect of the present invention, there is provided an inverter circuit for supplying an AC voltage to a discharge lamp, and a control for controlling an AC output voltage of the inverter circuit. And a discharge lamp lighting device that uses a part of the AC output voltage of the inverter circuit as a control power supply of the control circuit, when the control power supply becomes higher than a predetermined value, the positive and negative of the AC output voltage of the inverter circuit are provided. It is characterized in that one of them is controlled to be lowered, and the voltage on the side of the AC output voltage of the inverter circuit, which is lower in polarity, is used as the control power supply.

According to a second aspect of the present invention, there is provided an inverter circuit for supplying an AC voltage to the discharge lamp, and a control circuit for controlling the AC output voltage of the inverter circuit, and a part of the AC output voltage of the inverter circuit is provided. In a discharge lamp lighting device serving as a control power source for a control circuit, when the control power source becomes lower than a predetermined value, control is performed in such a manner that one of the positive and negative AC output voltages of the inverter circuit is increased, and the AC power of the inverter circuit is increased. It is characterized in that the voltage on the higher side of the positive or negative output voltage is used as the control power supply.

According to the third aspect of the present invention, when the control power supply is higher than a predetermined value, the control is performed in such a manner that one of the positive and negative AC output voltages of the inverter circuit is decreased, and the AC power of the inverter circuit is reduced. The voltage on the lower side of the positive and negative of the output voltage is used as the control power supply, and when the control power supply becomes lower than a predetermined value, control is performed to increase one of the positive and negative AC output voltages of the inverter circuit, It is characterized in that the voltage on the higher side of the positive and negative sides of the AC output voltage of the inverter circuit is used as the control power supply.

According to the fourth aspect of the present invention, the inverter circuit has a series circuit of at least two switching elements, and the control circuit controls the on-duties of the two switching elements so as to be unbalanced with each other. Thereby, the AC output voltage of the inverter circuit is controlled.

According to a fifth aspect of the present invention, when the control power supply becomes higher than the predetermined value, it is at the time of starting the discharge lamp.

According to a sixth aspect of the present invention, when the control power supply becomes lower than the predetermined value, the discharge lamp is lit.

According to a seventh aspect of the present invention, when the control power supply substantially coincides with the predetermined value, the discharge lamp is turned on.

According to the present invention, when the control power is higher than the predetermined value, the discharge lamp is started, and when the control power is lower than the predetermined value, the discharge lamp is turned on. Features.

According to the ninth aspect of the present invention, when the control power is higher than the predetermined value, the discharge lamp is started, and when the control power substantially matches the predetermined value, the discharge lamp is turned on. Features.

According to a tenth aspect of the present invention, the control power supply is obtained by partially rectifying the AC output voltage of the inverter circuit.

According to an eleventh aspect of the present invention, the resonance circuit is connected to the output terminal of the inverter circuit, and the discharge lamp and the control power supply are connected to the output terminal of the resonance circuit.

[0019]

Embodiment

(Embodiment 1) A circuit diagram of a first embodiment according to the present invention is shown in FIG. 1, and its operation waveform diagrams are shown in FIGS.

The difference from the circuit diagram of the conventional example shown in FIG. 6 is that a Zener diode Z is provided at both ends of a smoothing capacitor C5.
D1 is connected, and the same components as those of the other conventional examples are denoted by the same reference numerals and description thereof is omitted.

Next, the operation will be briefly described with reference to FIG. 2, FIG. 3, and FIG. As shown in FIGS. 2A and 2B, when the on-duties of the signal voltages HO and LO supplied from the control circuit 1 to the switching elements Q1 and Q2 substantially match,
As shown in FIG. 2C, at both ends of the transformer T1, an alternating-current high-frequency voltage VT1 whose peak values on the positive side and the negative side are substantially symmetrical is generated, and the output voltage of the control power supply circuit is as shown in FIG. ). Next, as shown in FIGS. 3A and 3B, of the on-duties of the signal voltages HO and LO, H
If the on-duty of O is greater than that of the unbalanced relationship, as shown in FIG. 3C, an AC high-frequency voltage VT2 having a low positive peak value is generated at both ends of the transformer T1, and the control power supply The output voltage of the circuit becomes a low voltage Vcc2 (<Vcc1) as shown in FIG. FIG.
As shown in FIGS. 4A and 4B, when the on-duty of the HO is smaller than the on-duty of the signal voltages HO and LO in an unbalanced relationship, as shown in FIG. A high-frequency voltage VT3 having a high positive peak is generated at both ends of the control power supply circuit, and the output voltage of the control power supply circuit is changed to a high-voltage Vcc3 (> Vcc) as shown in FIG.
1).

As described above, the switching elements Q1, Q
The output voltage of the control power supply circuit can be changed by changing the on-duty of the signal voltages HO and LO input to the control power supply circuit 2.

In the case of the start mode in which the high-frequency voltage generated in the transformer T1 is high, as shown in FIGS. 3A and 3B, the on-duty of the HO out of the on-duties of the signal voltages HO and LO is higher. When a high-frequency voltage VT2 having a low positive peak is generated at both ends of the transformer T1 as a large unbalanced waveform, the output voltage of the control power circuit becomes smaller as shown in FIG. It is possible to reduce the stress applied to the constituent circuit elements and obtain a stable output voltage of the control power supply circuit. However,
Since the high-frequency voltage generated in the transformer T1 in the lighting mode is considerably lower than that in the starting mode, when controlling as shown in FIG. 3, a sufficient output voltage of the control power supply circuit is obtained during the lighting mode. There is a need.

In the case of the lighting mode in which the high-frequency voltage generated in the transformer T1 is lower than that in the starting mode,
As shown in FIGS. 4A and 4B, the signal voltages HO and LO
When the high-frequency voltage VT3 having a higher positive peak at both ends of the transformer T1 is generated as an unbalanced waveform in which the HO on-duty is smaller than the on-duty of HO,
As shown in FIG. 4D, the output voltage of the control power supply circuit becomes higher, and a sufficient output voltage of the control power supply circuit is obtained. However, since the high-frequency voltage generated in the transformer T1 in the start-up mode is considerably higher than that in the lighting mode, a control power supply circuit such as connecting two Zener diodes in series when controlling as shown in FIG. It is necessary to take measures against the stress of the circuit elements constituting the above.

As described above, in the starting mode, the on-duty is controlled so as to reduce the stress of the circuit elements constituting the control power supply circuit, and a sufficient output voltage of the control power supply circuit is obtained in the lighting mode. When the on-duty is controlled in any of the modes, a relatively stable output voltage of the control power supply circuit can be obtained in any of the modes.

(Embodiment 2) A second embodiment according to the present invention will be described below.

In this embodiment, if it is difficult to greatly change the duty of the signal voltages HO and LO between the start mode and the lighting mode, the start mode will be described with reference to FIGS. ), The signal voltages HO, L
The on-duty of HO has a larger unbalanced waveform than the on-duty of O.
As shown in (a) and (b), the on-duties of the signal voltages HO and LO are made to substantially match.

With this configuration, it is possible to reduce the stress of the circuit elements constituting the control power supply circuit in the starting mode, and to compensate for a certain shortage of the output voltage of the control power supply circuit in the lighting mode. In any of the modes, a relatively stable output voltage of the control power supply circuit can be obtained.

(Embodiment 3) FIG. 5 is a circuit diagram of a third embodiment according to the present invention.

The difference from the circuit diagram of the first embodiment shown in FIG. 1 is that the switching elements Q1 and Q2 are MOS transistors.
Using an FET (hereinafter, referred to as a switching element), a capacitor C6 is connected in parallel to the output terminal of the full-wave rectifier DB in place of the smoothing capacitor C1, and the switching element Q1,
A capacitor C8 is connected in parallel to both ends of the series circuit of Q2,
A series circuit of an inductor L2, an electrolytic capacitor C7 and a diode D6 is connected in parallel to both ends of the switching element Q1, and a diode D7 is connected in parallel to both ends of the switching element Q2 via a diode D6.
A diode D4 is connected between one end of the secondary winding n1 and the negative output terminal of the full-wave rectifier DB, and the primary winding n1 of the transformer T1 is connected.
And a capacitor C9 is connected in parallel between the diode D5 and one end of the tertiary winding n3 of the transformer T1, and the same configuration as the other first embodiment. The description is omitted by attaching the reference numerals.

Next, the operation will be briefly described. In this circuit, by providing a circuit including the diode D4, the diode D5, and the capacitor C9, according to the on / off of the switching elements Q1 and Q2, the AC power supply Vs is switched from the AC power supply Vs to the inverter circuit over substantially the entire period of one cycle. Since the current is supplied via the load circuit, the input current can be made substantially sinusoidal, the input power factor can be increased, and the input current waveform distortion can be improved.

Further, by providing a circuit including the diodes D6 and D7, the inductor L2 and the electrolytic capacitor C7, when the switching element Q2 is turned on, the electrolytic capacitor C is connected via the diode D6 and the inductor L2.
While the output voltage of the full-wave rectifier DB is lower than the charging voltage of the electrolytic capacitor C7, the diode D
7, the charged voltage of the electrolytic capacitor C7 is discharged to the capacitor C8, and can act as a power source for the inverter circuit. This constitutes a contracted step-down chopper circuit.

This embodiment may be applied to any of the first and second embodiments.

[0034]

According to the first aspect of the present invention, it is possible to provide a discharge lamp lighting device capable of reducing stress applied to circuit elements constituting a control power supply circuit and supplying a stable control power supply voltage.

According to the second aspect of the present invention, it is possible to provide a discharge lamp lighting device capable of supplying a stable control power supply voltage.

According to the third aspect of the present invention, it is possible to provide a discharge lamp lighting device capable of reducing the stress applied to the circuit elements constituting the control power supply circuit and supplying a stable control power supply voltage.

According to the fourth aspect, in addition to the effects of the first to third aspects, a discharge lamp lighting device having a simple configuration can be provided.

According to the fifth aspect of the present invention, in addition to the effect of the first aspect, at the time of starting the discharge lamp, the discharge lamp lighting which can reduce the stress applied to the circuit elements constituting the control power supply circuit. Equipment can be provided.

According to the invention described in claim 6, according to claim 2,
In addition to the effect of the invention described in claim 3, a discharge lamp lighting device capable of supplying a stable control power supply voltage when the discharge lamp is turned on can be provided.

According to the invention of claim 7, in addition to the effect of the invention of claim 1, the output voltage of the inverter circuit does not greatly change between the time of starting the lamp and the time of lighting the lamp. When the lamp is turned on, a discharge lamp lighting device capable of supplying a stable control power supply voltage can be provided.

According to the eighth aspect of the invention, in addition to the effect of the third aspect of the invention, at the time of starting the discharge lamp, it is possible to reduce the stress applied to the circuit elements constituting the control power supply circuit. It is possible to provide a discharge lamp lighting device capable of supplying a stable control power supply voltage when the electric lamp is turned on.

According to the ninth aspect of the present invention, in addition to the effect of the first aspect of the present invention, at the time of starting the discharge lamp, it is possible to reduce the stress applied to the circuit elements constituting the control power supply circuit. A discharge lamp lighting device capable of supplying a stable control power supply voltage when the discharge lamp is turned on without significantly changing the output voltage of the inverter circuit between when the lamp is started and when the lamp is turned on can be provided.

According to the tenth aspect, the first aspect is provided.
In addition to the effects of the present invention, it is possible to provide a discharge lamp lighting device capable of configuring a control power supply with a simple configuration.

According to the eleventh aspect of the present invention, the first aspect is provided.
In addition to the effects of the inventions according to the tenth to tenth aspects, a discharge lamp lighting device capable of supplying the output voltage of the resonance circuit to the discharge lamp and the control power supply can be provided.

[Brief description of the drawings]

FIG. 1 shows a circuit diagram of a first embodiment according to the present invention.

FIG. 2 shows a first operation waveform diagram according to the embodiment.

FIG. 3 shows a second operation waveform chart according to the embodiment.

FIG. 4 shows a third operation waveform diagram according to the embodiment.

FIG. 5 shows a circuit diagram of a second embodiment according to the present invention.

FIG. 6 shows a circuit diagram of a conventional example according to the present invention.

[Explanation of symbols]

 1 control circuit La discharge lamp Q switching element

Claims (11)

[Claims] 1. An inverter circuit for supplying an AC voltage to a discharge lamp, and a control circuit for controlling an AC output voltage of the inverter circuit, wherein a part of the AC output voltage of the inverter circuit is controlled by a control power supply of the control circuit. In the discharge lamp lighting device, when the control power supply is higher than a predetermined value, control is performed in a direction to decrease one of the positive and negative AC output voltages of the inverter circuit, and the AC output voltage of the inverter circuit is controlled. A discharge lamp lighting device, characterized in that a voltage on the lower side of the positive and negative sides is used as the control power supply. 2. An inverter circuit for supplying an AC voltage to a discharge lamp, and a control circuit for controlling an AC output voltage of the inverter circuit, wherein a part of the AC output voltage of the inverter circuit is controlled by a control power supply of the control circuit. In the discharge lamp lighting device, when the control power supply is lower than a predetermined value, the control circuit controls the AC output voltage of the inverter circuit so as to increase one of the positive and negative AC output voltages, and controls the AC output voltage of the inverter circuit. A discharge lamp lighting device, characterized in that the voltage on the higher side of the positive and negative of the above is used as the control power supply. 3. When the control power supply is lower than a predetermined value, control is performed in such a manner that one of the positive and negative AC output voltages of the inverter circuit is increased, and the positive and negative AC output voltages of the inverter circuit are increased. 2. The discharge lamp lighting device according to claim 1, wherein the voltage on the increased side is used as the control power supply. 4. The inverter circuit has a series circuit of at least two switching elements, and the control circuit controls the on-duties of the two switching elements in a direction in which the on-duties of the two switching elements are unbalanced with each other. 4. The discharge lamp lighting device according to claim 1, wherein the device controls an AC output voltage of the circuit. 5. The discharge lamp lighting device according to claim 1, wherein the control power supply becomes higher than a predetermined value when the discharge lamp is started. 6. The discharge lamp lighting device according to claim 2, wherein the control power supply becomes lower than a predetermined value when the discharge lamp is turned on. 7. The discharge lamp lighting device according to claim 1, wherein when the control power supply substantially matches a predetermined value, the discharge lamp is lit. 8. The method according to claim 8, wherein the control power is higher than a predetermined value when the discharge lamp is started, and when the control power is lower than a predetermined value when the discharge lamp is turned on. Item 3. A discharge lamp lighting device according to Item 3. 9. The method according to claim 8, wherein the control power supply is higher than a predetermined value when the discharge lamp is started, and when the control power supply substantially matches the predetermined value, the discharge lamp is turned on. Item 10. The discharge lamp lighting device according to Item 1. 10. The discharge lamp lighting device according to claim 1, wherein the control power supply is obtained by partially rectifying an AC output voltage of the inverter circuit. 11. The control circuit according to claim 1, wherein a resonance circuit is connected to an output terminal of the inverter circuit, and the discharge lamp and the control power supply are connected to an output terminal of the resonance circuit. A discharge lamp lighting device according to any one of the above.