JP3035041B2 - Lighting device for high pressure discharge lamp - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art FIG. 7 shows a circuit configuration of a conventional example.
This conventional circuit switches a pair of transistors, etc.
Element Q₁, Q_TwoTo the DC power supply 4
Switching element Q₁, Q_TwoOn and off alternately
General half-bridge type inverter circuit 1
And one switching element Q_TwoIn parallel to
1 capacitor C₁, Inductance element for current limiting
L₁, The second capacitor C_TwoSeries circuits connected in parallel
And capacitor C_TwoThe secondary winding N of the pulse transformer PT
_TwoVia metal halide lamp, mercury lamp, high pressure
A high-pressure discharge lamp 2 such as a thorium lamp is connected. Soshi
Capacitor C_TwoTo the igniter booster circuit 3 in parallel
Then, the output of the igniter booster circuit 3 is set to a switch SW.
Through the primary winding N of the pulse transformer PT₁Connected to
You.

This conventional circuit is shown in FIGS. 8 (a) and 8 (b).
Switching element Q₁, Q_TwoAlternating high frequency (example
For example, if it is turned on and off at 100 to several hundred kHz,
Switching element Q₁, Q_TwoAnd switching element Q₁,
Q_TwoDiode D connected in parallel to₁, D_TwoThe figure
8 (c) and 8 (d)_Q1, I_D1, I_Q2,I _D2
As a result, the high-pressure discharge lamp 2 shown in FIG.
High frequency lamp current I of sinusoidal_LaFlows, high pressure discharge
The lamp 2 keeps lighting stably.

Some high pressure discharge lamps have a starting time of several tens.
Some devices do not start unless a high voltage of 00 V is applied to both electrodes, and the high pressure discharge lamp lighting device generally includes the igniter booster circuit 3 and the igniter circuit IG including the pulse transformer PT. This igniter circuit IG
Obtains a high voltage by the igniter booster circuit 3 and further boosts this high voltage by the pulse transformer PT to increase its secondary winding N ₂
To generate a high pulse voltage, which is applied to both ends of the high pressure discharge lamp 2 of this pulse voltage through a capacitor C ₂ is generally used.

FIG. 9 specifically shows the igniter booster circuit 3.
The conventional example is shown, and the igniter used in this conventional example is shown.
The booster circuit 3 is a capacitor C_Three~ C₆, Diode D_Three
~ D ₆This consists of a multiple voltage circuit composed of
The operation of the igniter booster circuit 3 is as follows. Toes
When the high pressure discharge lamp 2 is not turned on,
Since the impedance is near infinity, the inverter circuit 1
Operates with no load. At this time, the output of the inverter circuit 1
Between the forces A and B, the peak value as shown in FIG.
Sinusoidal voltage V_ABOccurs.

This voltage V_ABMulti-voltage circuit with power supply
The igniter booster circuit 3 composed of That is, point B
In a cycle in which the potential of point A is higher than point A, point B → D_Three
→ C _Three→ Current flows in the direction of point A, and capacitor C_ThreeNo electricity
The voltage rises to E (V), which is equal to the power supply voltage. Then reverse
In the cycle (when the potential of point A is higher than point B), point A →
C_Three→ D_Four→ C_Four→ Current flows in the direction of point B,
Sa C_FourHas a power supply voltage E and a capacitor C _ThreeVoltage E is added
Voltage 2E (V).

In the next cycle, point B → C ₄ → D ₅ →
A current flows in the direction of C ₅ → C ₃ → Point A. By repeating this operation, a voltage 2E (V) that is twice the power supply voltage E is applied to each of the capacitors C ₄ , C ₅ , and C ₆ . Looking at the voltage at point C with reference to point B, a DC voltage of 4E (V) can be obtained. In the circuit of FIG. 9, the igniter booster circuit 3 for generating a quadruple voltage has been described. However, it is needless to say that a higher DC voltage can be obtained by connecting capacitors and diodes in multiple stages in the multiple voltage circuit.

By repeating the above operation, the voltage V _{CB at the} point C rises as shown in FIG. When the at time T ₁ to the primary winding N ₁ of the pulse transformer PT to turn on the switch SW are connected in series, the charge stored in the capacitor C _4, C ₆ is the pulse transformer PT 1
Rapidly discharged via the primary winding N _1. High pulse voltage Vp is the secondary winding N ₂ in accordance with the step-up ratio in this case the pulse transformer PT is generated as shown in Figure 10 (c).

The high pulse voltage Vp is applied to the capacitor C ₂
Is applied to both ends of the high pressure discharge lamp 2 to start the high pressure discharge lamp 2. When the operation is not started by one pulse, this operation is repeated to generate pulses at T ₂ , T ₃ ,. Here, in the above-described conventional circuit, the high pulse voltage V
It is desirable that the peak value of p be several thousand V or more and the pulse width be several μsec or more. The pulse height is C ₄ ,
The pulse width increases in proportion to the voltage value of C ₆ and the turns ratio of the pulse transformer PT, and the pulse width is proportional to the capacitance values of the capacitors C ₄ and C ₆ and the inductance value of the primary winding N ₁ of the pulse transformer PT. It becomes wider.

[0010]

By the way, this kind of 1
Inductance value of the inductance element L ₁ is a limiting factor in system turned on at the high frequencies above 00KHz number 10μH about, and the value of the capacitor C ₂ of the resonance becomes a small value as several nF. Therefore the high-pressure discharge lamp 2 and the capacitors C ₄ inductor booster circuit 3 consisting of 2 inductance values of windings N ₂ and polyploid pressure circuit of the pulse transformer PT which are connected in series, C _5, the capacitance value of C ₆ It is difficult to set a large value in terms of circuit operation.

For this reason, there is a disadvantage that it is difficult to secure a desired pulse height and pulse width, and the starting performance is poor.
The present invention has been made in view of the above points, and an object of the present invention is to provide a lighting device for a high pressure discharge lamp which has a simple circuit configuration and sufficiently secures the starting performance of the high pressure discharge lamp.

[0012]

In order to achieve the above object, according to the present invention, a series circuit of at least a pair of switching elements which are alternately turned on and off is connected to a DC power supply, and a current-limiting inductance element is provided. 1, an inverter circuit in which a series circuit of a second capacitor is connected in parallel to one of the pair of switching elements, a DC voltage generating circuit using the voltage across the second capacitor as an input power supply, and an output of the DC voltage generating circuit. And a pulse transformer in which a secondary winding is connected in parallel to the second capacitor via a high-pressure discharge lamp, and an output of the DC voltage generating circuit is connected to a second capacitor. It was done.

According to a second aspect of the present invention, an impedance element is connected in parallel with the second capacitor, and the inverter circuit operates intermittently. Further, in the invention according to claim 3, a series circuit of at least a pair of switching elements that are alternately turned on and off is connected to a DC power supply, and a series circuit of a current-limiting inductance element and first and second capacitors is connected to the pair of switching elements. An inverter circuit connected in parallel to one side, a DC voltage generation circuit using the voltage across the second capacitor as an input power supply, and a pulse transformer having a secondary winding connected in parallel to the second capacitor via a high-pressure discharge lamp Wherein the primary winding of the pulse transformer is connected in parallel to the first capacitor, and the output of the DC voltage generating circuit is connected to the second capacitor.

[0014]

According to the first aspect of the present invention, the pulse voltage output from the secondary winding of the pulse transformer is further added to the voltage obtained by superimposing the voltage across the second capacitor and the output voltage of the DC voltage generating circuit. Can be applied to the high-pressure discharge lamp, so that the high-pressure discharge lamp can be reliably started, and the starting performance is significantly improved.

According to the second aspect of the present invention, the voltage across the high pressure discharge lamp can be increased intermittently, and the effective voltage of the voltage across the high pressure discharge lamp can be substantially reduced while securing the peak value of the pulse voltage. And the safety is improved. Further, according to the third aspect of the present invention, it is possible to generate a high-voltage pulse by utilizing the electric charge stored in the first capacitor, and the pulse width is widened only by increasing the capacity of the first capacitor. It is possible to further improve the starting performance.

[0016]

The present invention will be described below with reference to examples. (Embodiment 1) FIG. 1 shows a circuit of this embodiment. In this embodiment, a multiple voltage circuit which is basically the same as the circuit shown in FIG. via the diode D ₇ from point C of the igniter boosting circuit 3 of 9 is obtained by adding a circuit connecting the DC voltage output from the second igniter boosting circuit 3 is a DC voltage generating circuit to the capacitor C _2.

That is, in the present embodiment, when there is no load before the high-pressure discharge lamp 2 is started, the peak value E between the points A and B of the inverter circuit 1 as shown in FIG. The voltage V _{AB in} the form of a sine wave is generated, and the igniter booster circuit 3 including the multiple voltage circuit receives the voltage V _AB to generate a high DC voltage. Since here the present embodiment the circuit is fed back to the point A of the inverter circuit 1 as a power source of the igniter booster circuit 3 through the diode D ₇ of the DC voltage, the voltage V _AB between the output AB Figure 2 As shown in (a), the voltage is a voltage on which a DC component is superimposed.

On the other hand, the voltage V _{CB at the} point C is as shown in FIG. Then, when the switch SW is turned on at the time T ₁ when the voltage V _CB rises to a certain value, the secondary winding N ₂ of the pulse transformer PT is operated according to the principle described in the conventional example.
2 shows a pulse voltage Vp is generated as indicated by (c), is applied to both ends of the high-pressure discharge lamp 2 via the capacitor C _2.

At this time, the voltage V _DB across the high-pressure discharge lamp 2
FIG. 3 shows a comparison between the voltage V _{DB of the} conventional example and the voltage V _{DB of the} conventional example. In the conventional example, the operation of superimposing the voltage E between the outputs A and B is performed as shown in FIG. In this embodiment, a pulse voltage V is added to a voltage obtained by superimposing the voltage E between A and B and the output voltage of the igniter booster circuit 3 as shown in FIG.
The voltage on which p is superimposed is applied to both ends of the high-pressure discharge lamp 2.

Therefore, compared to the prior art, a voltage sufficient for starting is applied to the high pressure discharge lamp 2, so that the starting performance for the high pressure discharge lamp 2 is significantly improved. (Embodiment 2) FIG. 4 shows a circuit according to the present embodiment. In this embodiment, the output of the igniter booster circuit 3 is a diode D.
₇ is connected to the point A of the inverter circuit 1 through the same as the first embodiment, but the primary winding N of the pulse transformer PT is
₁ and a switch SW are connected to a first capacitor C _1.
The parallel connection, is characterized in that to generate a high-voltage pulse voltage using the charge stored in the capacitor C _1.

In the first embodiment, the capacitor of the multiple voltage circuit is used.
Sensor C_Four, C₆A pulse using the charge stored in the
In the second embodiment, the capacitor C_Four, C₆
And C ₁When comparing the capacitance value of each capacitor of
Normal C₁≫C_Four, C₆So that C₁The value of C_Four, C
₆Is set to be two or three digits larger. Therefore Igna
If the capacity of the capacitor of the ita booster circuit 3 is expanded, the pulse width
Similarly, in this embodiment, the capacitor C₁Charge of
Can be used to increase the pulse width.
The starting performance can be further improved compared to the first embodiment.
You.

(Embodiment 3) FIG. 5 shows a circuit of this embodiment. In this embodiment, a capacitor in the igniter booster circuit 3 and first and second capacitors C ₁ and C 2 are added to the circuit of Embodiment ₁ . the impedance element Z for discharging the charges stored in the C ₂ connected between the output a-B of the inverter circuit 1 and the switching element to Q ₁ inverter circuit 1, Q
_It is characterized in that ₂ operates intermittently.

That is, in the first embodiment, if the high-pressure discharge lamp 2 cannot be started at the end of its life, or if it is turned on immediately after being turned off, the high-pressure discharge lamp 2 does not break down at the original pulse voltage. In addition, the high-pressure discharge lamp 2 does not always start, and even a minute discharge due to a pulse may not occur. In this case, in the first embodiment, the state in which the voltage V _DB across the high-pressure discharge lamp 2 is high as shown in FIG.

On the other hand, in this embodiment, the voltage V _DB across the high-pressure discharge lamp 2 is increased intermittently as shown in FIG.
The effective voltage of _DB is substantially reduced to improve safety. That is, the switching elements Q ₁ and Q ₂ are oscillated as shown in FIGS. 6A and 6B to increase the voltage V _DB across the high pressure discharge lamp 2 during the oscillation period and generate the pulse voltage Vp. In addition, a pause period is provided by intermittently oscillating the operation, and the electric charge stored in the capacitors C ₁ , C _{2 and the} like is discharged through the impedance element Z during the pause period to lower the voltage V _DB between both ends. It is.

Although each of the above embodiments uses the half-bridge type inverter circuit 1, it can be applied to a full-bridge type inverter circuit.

[0026]

According to the first aspect of the present invention, a series circuit of at least a pair of switching elements that are alternately turned on and off is connected to a DC power supply, and a series circuit of a current limiting inductance element and first and second capacitors is connected to the pair. An inverter circuit connected in parallel to one of the switching elements, a DC voltage generating circuit using the voltage across the second capacitor as an input power supply, and an output of the DC voltage generating circuit connected to a primary winding;
A pulse transformer in which a secondary winding is connected in parallel to the second capacitor via a high-pressure discharge lamp, and the output of the DC voltage generation circuit is connected to the second capacitor.
A voltage obtained by superimposing a pulse voltage output from the secondary winding of the pulse transformer on a voltage obtained by superimposing the voltage across the second capacitor and the output voltage of the DC voltage generation circuit can be applied to the high-pressure discharge lamp. As a result, the high-pressure discharge lamp can be reliably started, and the starting performance is significantly improved with a simple circuit configuration.

According to the second aspect of the present invention, since an impedance element is connected in parallel with the second capacitor and the inverter circuit is operated intermittently, it is possible to intermittently increase the voltage across the high pressure discharge lamp. Thus, the effective voltage of the voltage between both ends of the high-pressure discharge lamp can be substantially reduced while securing the peak value of the pulse voltage, and there is an effect that safety is improved.

Further, according to a third aspect of the present invention, a series circuit of at least a pair of switching elements that are turned on and off alternately is connected to a DC power supply, and a current-limiting inductance element,
An inverter circuit in which a series circuit of a second capacitor is connected in parallel to one of the pair of switching elements; a DC voltage generation circuit that uses the voltage across the second capacitor as an input power supply; And a pulse transformer connected in parallel to the second capacitor via a primary winding of the pulse transformer connected in parallel to the first capacitor and an output of the DC voltage generating circuit connected to the second capacitor. As a result, a high-voltage pulse voltage can be generated by using the charge (energy) of the first capacitor, and the pulse width can be widened only by increasing the capacity of the first capacitor, and the starting performance can be increased. Is further improved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a first embodiment of the present invention.

FIG. 2 is a waveform diagram for explaining the operation of the first embodiment of the present invention.

FIG. 3 is a comparative explanatory diagram of the first embodiment of the present invention.

FIG. 4 is a circuit diagram of a second embodiment of the present invention.

FIG. 5 is a circuit diagram of a third embodiment of the present invention.

FIG. 6 is a waveform diagram for explaining the operation of the third embodiment of the present invention.

FIG. 7 is a circuit diagram of a conventional example.

FIG. 8 is a waveform diagram for explaining the operation of the conventional example.

FIG. 9 is a circuit diagram showing a specific circuit of a conventional igniter booster circuit.

FIG. 10 is a waveform diagram for explaining the operation of the conventional igniter booster circuit.

[Explanation of symbols]

First inverter circuit 2 high-pressure discharge lamp 3 igniter booster circuit 4 direct-current power source Q ₁ switching element Q ₂ switching element PT pulse transformer N ₁ 1 winding N ₂ 2 winding C ₁ capacitor C ₂ capacitors L ₁ inductance element D ₇ diode

Claims (3)

(57) [Claims] 1. A series circuit of at least a pair of switching elements which are turned on and off alternately is connected to a DC power supply, and a series circuit of a current limiting inductance element and first and second capacitors is connected in parallel to one of the pair of switching elements. A connected inverter circuit, a DC voltage generating circuit using the voltage across the second capacitor as an input power supply, an output of the DC voltage generating circuit connected to a primary winding, and a secondary winding connected via a high-pressure discharge lamp. And a pulse transformer connected in parallel with the second capacitor, wherein the output of the DC voltage generating circuit is connected to the second capacitor. 2. The lighting device for a high pressure discharge lamp according to claim 1, wherein an impedance element is connected in parallel with said second capacitor, and said inverter circuit is operated intermittently. 3. A series circuit of at least a pair of switching elements that are turned on and off alternately is connected to a DC power supply, and a series circuit of a current limiting inductance element and first and second capacitors is connected in parallel to one of the pair of switching elements. It comprises an inverter circuit connected thereto, a DC voltage generating circuit using the voltage across the second capacitor as an input power supply, and a pulse transformer having a secondary winding connected in parallel to the second capacitor via a high-pressure discharge lamp. A lighting device for a high pressure discharge lamp, wherein a primary winding of the pulse transformer is connected in parallel to a first capacitor, and an output of a DC voltage generating circuit is connected to a second capacitor.