JPH04322094A - Discharging lamp lighting apparatus - Google Patents

Abstract

PURPOSE:To suppress the yield capacity of a switching device and an inductor and lower the generation of noise. CONSTITUTION:A discharging lamp DL having an inductor L1 connected in series and a capacitor C1 connected in parallel is square wave-lighted by an inverter. At the time the square wave transfers from one level to the other level and the time of transferring reversely, the condition of the pulse voltage is altered temporarily to quickly carry out rising and trailing of the lamp current of the discharging lamp DL at the time of reversing the polarity, so that re-igniting voltage is prevented from being generated in the discharging lamp DL. Also at the time the square wave transfers from one level to the other level and the time of the transferring reversely, since the accumulated electric charges of the capacitor C1 are discharged by an accumulated charge discharging means before the pulse duration of the pulse voltage is extended, the current due to the accumulated electric charges of the capacitor C1 is suppressed from flowing rapidly to the inductor L1 and switching devices Q1, Q2 and the wave height of it is made to be almost the same level as that at a normal time.

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 a high-pressure discharge lamp with a rectangular wave using various inverters such as a full-bridge type or a half-bridge type.

0002

2. Description of the Related Art FIG. 11 shows a circuit diagram of a conventional discharge lamp lighting device for lighting a high-pressure discharge lamp in a rectangular wave using a half-bridge type inverter. In Figure 11, VDC is a DC power supply, DL is a discharge lamp, and L1 is a discharge lamp DL.
The inductor C1 is connected in series with the discharge lamp DL.
This is a capacitor connected in parallel with . C2 and C3 are capacitors forming a half-bridge inverter IV1, respectively, and Q1 and Q2 are switching elements forming a half-bridge inverter IV1, respectively. DR1 and DR2 are drive circuits G that turn on and off the switching elements Q1 and Q2, respectively.
1 and G2 are AND gates, G3 is a NOT gate, OS3 is an oscillator, and VF is a voltage-frequency converter.

[0003] In the discharge lamp lighting device having the above configuration, a half-bridge type inverter IV1 is connected to a discharge lamp DL having an inductor L1 connected in series and a capacitor C1 connected in parallel. The configuration is such that the pulse voltage of the second polarity is repeatedly applied during the second period to light the discharge lamp DL in a rectangular wave, and when the polarity of the lamp current of the discharge lamp DL is reversed, the pulse voltage is The lamp is configured to include a pulse control means (not shown) that changes the state of the pulse voltage by temporarily widening the pulse width of the lamp, thereby causing the lamp current of the discharge lamp to rapidly rise and fall.

The operation of the discharge lamp lighting device shown in FIG. 11 will be explained below with reference to FIGS. 12 and 13. Oscillator OS
3, as shown in FIG. 12(a) from the output end A.
A voltage VA is generated which is at a high level during a period T1 and at a low level during a second period T2. In addition, from the output terminal B, as shown in FIG. 12(b), the voltage VA shown in FIG. 12(a)
During a predetermined period after the fall and rise of VB3 (until the lamp current reaches a predetermined level), a voltage VB3 whose voltage value is lower than normal is generated. The voltage VA at the output terminal A is applied to one input terminal of an AND gate G1, and is also applied to an AND gate via a NOT gate G3.
It is applied to one input terminal of gate G2.

Further, the voltage VB3 at the output terminal B is input to a voltage-frequency converter VF. This voltage-frequency converter VF generates a pulse voltage with a frequency (duty ratio is constant) according to the input voltage VB3, and converts this into AN
Commonly added to D gates G1 and G2. The outputs of AND gates G1 and G2 are respectively connected to drive circuit DR1.
, DR2, the switching element Q1
, Q2, respectively.

FIG. 13(a) shows the gate voltage VQ1 input from the drive circuit DR1 to the gate of the switching element Q1, and FIG. 13(b) shows the gate voltage VQ2 input from the drive circuit DR2 to the gate of the switching element Q2. The figure (c) shows the current IL1 flowing through the inductor L1, and the figure (d) shows the lamp current IDL flowing through the discharge lamp DL.

In FIG. 13, before time t0, there is a period T
2, and the period after time t0 corresponds to period T1. Before time t0, the gate voltage VQ2 is supplied to the switching element Q2, and the switching element Q2 repeats on and off, and after time t0, the gate voltage VQ1 is supplied to the switching element Q1, and the switching element Q1 repeats on and off.

When the switching element Q2 is repeatedly turned on and off, a negative current IL1 flows through the inductor L1.
(in FIG. 13, a downward current) flows, and when the switching element Q1 is repeatedly turned on and off, a positive current IL1 (in FIG. 13, an upward current) flows through the inductor L1. At this time, a negative lamp current IDL (downward current in FIG. 13) flows through the discharge lamp DL during a period T2, and a positive lamp current IDL (an upward current in FIG. 13) flows during a period T1.

At the time of transition from period T2 to period T1, that is, when lamp current IDL changes from negative polarity to positive polarity, the pulse frequency of gate voltage VQ1 applied to the gate of switching element Q1 becomes lower and the pulse width becomes normal. The lamp current IDL rises faster. Also, when transitioning from period T1 to period T2, the pulse width of gate voltage VQ2 applied to the gate of switching element Q2 becomes wider than in normal times, and the fall of lamp current IDL becomes faster, as described above. Note that the period during which the pulse width is widened is until the lamp current IDL reaches a predetermined value.

As mentioned above, when the polarity of the lamp current IDL is reversed, the switching element Q1 or Q2
The reason for temporarily widening the pulse width of the gate voltages VQ1 and VQ2 is that if the switching elements Q1 and Q2 are turned on and off while the pulse width of the gate voltages VQ1 and VQ2 is always constant, the lamp current increases when the polarity of the lamp current IDL is reversed. This is because the rising and falling of the current IDL becomes delayed, and a restriking voltage is generated, causing the discharge lamp DL to flicker.

[0011]

[Problems to be Solved by the Invention] This discharge lamp lighting device has the following characteristics: When the polarity of the lamp current IDL of the discharge lamp DL is reversed,
The pulse widths of the gate voltages VQ1 and VQ2 applied to the switching elements Q1 and Q2 were widened so that the lamp current IDL rose and fell rapidly.
At this time, a voltage that is the sum of the voltage of the DC power supply VDC and the lamp voltage (equal to the voltage VC1 of the capacitor C1) is applied to the inductor L1, so an excessive current flows through the inductor L1 as the current IL1 compared to the normal state. . Therefore, it is necessary to use large capacity switching elements Q1, Q2 and inductor L1, and since a spike-like current with a high peak value flows, this also leads to the generation of noise.

[0012] Accordingly, an object of the present invention is to provide a discharge lamp lighting device that can suppress the withstand capacity of switching elements and inductors, and can also reduce the generation of noise.

[0013]

[Means for Solving the Problems] A discharge lamp lighting device of the present invention repeatedly applies a pulse voltage of a first polarity during a first period from an inverter to a discharge lamp having an inductor connected in series and a capacitor connected in parallel. Apply the second
During the period, a pulse voltage of the second polarity is repeatedly applied to light the discharge lamp in a rectangular wave. In addition, the state of the pulse voltage is temporarily changed at the transition from the first period to the second period and from the second period to the first period, and the polarity reversal of the lamp current of the discharge lamp is performed. A pulse control means for rapidly rising and falling is provided, and the state of the pulse voltage is controlled by the pulse control means at the time of transition from the first period to the second period and from the second period to the first period. Before changing the capacitor, a charge discharge means is provided to store and release the charge accumulated in the capacitor.

[0014]

[Operation] According to the configuration of the present invention, the pulse control means temporarily changes the state of the pulse voltage at the transition from the first period to the second period and from the second period to the first period. By changing this, the lamp current of the discharge lamp rapidly rises and falls when the polarity is reversed, so that it is possible to suppress the generation of a restriking voltage in the discharge lamp.

[0015] Furthermore, before the state of the pulse voltage is changed by the pulse control means at the transition from the first period to the second period and from the second period to the first period, the accumulated charge releasing means Since the accumulated charges in the capacitor are discharged, it is possible to prevent the current caused by the accumulated charges in the capacitor from flowing rapidly to the inductor and the switching element, and the peak value thereof can be made comparable to that in normal times.

[0016]

【Example】

(First Embodiment) FIG. 1 shows a circuit diagram of a discharge lamp lighting device according to a first embodiment of the present invention, which lights a high-pressure discharge lamp in a rectangular wave using a half-bridge type inverter. In Figure 1, VDC is a DC power supply, DL is a discharge lamp, and L1
is an inductor connected in series to the discharge lamp DL, C1
is a capacitor connected in parallel to the discharge lamp DL. C
2 and C3 are capacitors forming a half-bridge inverter IV1, respectively, and Q1 and Q2 are switching elements forming a half-bridge inverter IV1, respectively. DR1 and DR2 are drive circuits that turn on and off the switching elements Q1 and Q2, respectively, G1 and G2 are AND gates, G3 is a NOT gate, OS1 is an oscillator, and VF is a voltage-frequency converter.

In the discharge lamp lighting device having the above configuration, a half-bridge type inverter IV1 is connected to a discharge lamp DL having an inductor L1 connected in series and a capacitor C1 connected in parallel. A pulse voltage of the second polarity is repeatedly applied during the second period, and the discharge lamp DL is lit in a rectangular wave.

[0018] Furthermore, the state of the pulse voltage can be changed by temporarily widening the pulse width of the pulse voltage at the transition from the first period to the second period and from the second period to the first period. a pulse control means (not shown) that changes the lamp current of the discharge lamp DL to rapidly rise and fall when the polarity is reversed; The device is configured to include an accumulated charge release means (not shown) that releases the accumulated charge of the capacitor C1 before the pulse control means changes the state of the pulse voltage at the time of transition to the first period. The output waveform of the oscillator OS1 is controlled as shown in FIG. 2 by the control means and the accumulated charge release means.

The operation of the discharge lamp lighting device shown in FIG. 1 will be explained below with reference to FIG. 2.
This will be explained with reference to FIG. The oscillator OS1 starts from the output terminal A during the first period T, as shown in FIG. 2(a).
1 generates a voltage VA which is at a high level and which is at a low level during a second period T2. Also, from output end B,
As shown in (b), after the fall of the voltage VA in (a) of the same figure, and for a certain period after the fall (capacitor C1
Until the charge is released (that is, until the lamp current IDL exceeds zero), the voltage value will be higher than normal, and for a predetermined period after that (until the lamp current IDL reaches a predetermined level), the voltage will be higher than normal. A voltage VB1 having a low value is generated. The voltage VA at the output terminal A is applied to one input terminal of an AND gate G1, and is also applied to one input terminal of an AND gate G2 via a NOT gate G3.

Further, the voltage VB1 at the output terminal B is input to a voltage-frequency converter VF. This voltage-frequency converter VF generates a pulse voltage with a frequency (duty ratio is constant) according to the input voltage VB1, and converts this into AN
Commonly added to D gates G1 and G2. The outputs of AND gates G1 and G2 are respectively connected to drive circuit DR1.
, DR2, the switching element Q1
, Q2, respectively.

FIG. 3(a) shows the gate voltage VQ1 input from the drive circuit DR1 to the gate of the switching element Q1, and FIG. 3(b) shows the gate voltage VQ2 input from the drive circuit DR2 to the gate of the switching element Q2. The figure (c) shows the current IL1 flowing through the inductor L1, and the figure (d) shows the lamp current IDL flowing through the discharge lamp DL.

In FIG. 3, before time t0, period T2
, and the period after time t0 corresponds to period T1. Before time t0, the gate voltage VQ2 is supplied to the switching element Q2, and the switching element Q2 is repeatedly turned on and off, and after time t0, the switching element Q2 is supplied with the gate voltage VQ2.
The gate voltage VQ1 is supplied to the switching element Q1, and the switching element Q1 is repeatedly turned on and off.

When the switching element Q2 is repeatedly turned on and off, a negative current IL1 flows through the inductor L1.
(in FIG. 3, a downward current) flows, and when the switching element Q1 is repeatedly turned on and off, a positive current IL1 (in FIG. 3, an upward current) flows through the inductor L1. At this time, a negative lamp current IDL (downward current in FIG. 3) flows through the discharge lamp DL during a period T2, and a positive lamp current IDL (an upward current in FIG. 3) flows during a period T1.

At the time of transition from period T2 to period T1, that is, when lamp current IDL changes from negative polarity to positive polarity, the pulse frequency of gate voltage VQ1 applied to the gate of switching element Q1 increases once, and the pulse width increases. After becoming narrower than normal (period T11), the pulse frequency of gate voltage VQ1 becomes lower and the pulse width becomes wider than normal (period T12);
The pulse frequency of 1 returns to its original state, and the pulse width also returns to its original state (period T13).

As a result, when transitioning from period T2 to period T1, that is, when lamp current IDL changes from negative polarity to positive polarity, switching element Q1 is first turned on and off with a narrow pulse width, thereby reducing the accumulation in capacitor C1. After the charges are released and the charges accumulated in the capacitor C1 are released, the switching element Q1 is turned on and off with a wide pulse width, thereby rapidly raising the lamp current IDL.

Also, when transitioning from period T1 to period T2, similarly to the above, after the pulse frequency of gate voltage VQ2 applied to the gate of switching element Q2 becomes higher and the pulse width becomes narrower than normal, The pulse frequency of gate voltage VQ2 becomes lower and the pulse width becomes wider than normal, and then the pulse frequency of gate voltage VQ2 returns to its original state and the pulse width also returns to its original state. As a result, after the accumulated charge in the capacitor C1 is released, the lamp current IDL is rapidly reduced. Note that the period for narrowing the pulse width is until the accumulated charge in capacitor C1 is exhausted, and the period for widening the pulse width is for lamp current ID.
This is until L reaches a predetermined value.

[0027] The discharge lamp lighting device of this embodiment has the following advantages: at the time of transition from the first period to the second period and from the second period to the first period.
During the transition to the period, the frequency of the pulse voltage is temporarily lowered to make the rise and fall of the lamp current IDL of the discharge lamp DL more rapid when the polarity is reversed. can be deterred,
Flickering of the discharge lamp DL can be prevented.

Furthermore, before lowering the frequency of the pulse voltage at the transition from the first period to the second period and from the second period to the first period, the accumulated charge in the capacitor C1 is released. , the current due to the accumulated charge in capacitor C1 suddenly flows through inductor L1 and switching element Q.
1 and Q2 can be suppressed. Therefore, the peak value can be made comparable to that in normal times, and the inductor L1 and switching element Q1,
It is possible to keep the withstand amount of Q2 small, and
The generation of noise can be reduced.

(Second Embodiment) FIG. 4 shows a circuit diagram of a discharge lamp lighting device according to a second embodiment of the present invention, which lights a high-pressure discharge lamp in a rectangular wave using a half-bridge type inverter. In FIG. 4, PM is a pulse width modulation circuit,
It replaces the voltage-frequency conversion circuit VF in FIG. 1,
Other configurations are similar to those in FIG. 1.

In this embodiment, the oscillator OS1 is as shown in FIG.
Voltages VA and VB as shown in a) and (b) are output, and their waveforms are the same as in FIGS. 1(a) and (b). If the pulse width modulation circuit PM is used as in this embodiment,
Gate voltage VQ1 of switching elements Q1 and Q2,
VQ2, current IL1 and lamp current IDL are as shown in FIGS. 6(a) to 6(d), respectively. In other words, when transitioning from period T2 to period T1, that is, when lamp current IDL changes from negative polarity to positive polarity, switching element Q1
After the pulse width of the gate voltage VQ1 applied to the gate of the gate becomes narrower than normal (period T11, frequency is constant), the pulse width of the gate voltage VQ1 becomes wider than normal (period T12), and then the gate voltage The pulse width of VQ1 returns to its original state (period T13).

As a result, when transitioning from period T2 to period T1, that is, when lamp current IDL changes from negative polarity to positive polarity, switching element Q1 is first turned on and off with a narrow pulse width, thereby reducing the accumulation in capacitor C1. After the charges are released and the charges accumulated in the capacitor C1 are released, the switching element Q1 is turned on and off with a wide pulse width, thereby rapidly raising the lamp current IDL.

Furthermore, when transitioning from period T1 to period T2, similarly to the above, after the pulse width of gate voltage VQ2 applied to the gate of switching element Q2 becomes narrower than normal, the pulse width of gate voltage VQ2 becomes narrower. The pulse width of the gate voltage VQ2 becomes wider than normal, and then the pulse width of the gate voltage VQ2 returns to its original state. As a result, after the accumulated charge in the capacitor C1 is released, the lamp current IDL is rapidly reduced. Note that the period for narrowing the pulse width is until the accumulated charge in capacitor C1 is exhausted, and the period for widening the pulse width is for lamp current I.
This is until DL reaches a predetermined value.

The effects of this embodiment are similar to those of the first embodiment. (Third Embodiment) FIG. 7 shows a circuit diagram of a discharge lamp lighting device according to a third embodiment of the present invention, which lights a high-pressure discharge lamp in a rectangular wave using a half-bridge type inverter. This discharge lamp lighting device uses an oscillator OS2 in place of the oscillator OS1 shown in FIG. 1, and a series circuit of a switch SW and a resistor R whose on/off is controlled by the output of the oscillator OS2 is connected in parallel to a capacitor C1. , the other configurations are the same as those in FIG.

In this embodiment, the oscillator OS2 is connected to the terminal A
outputs a voltage VA as shown in FIG. 8(a) from terminal B.
The difference from the conventional example shown in FIG. 11 is that a voltage VB is generated from the terminal C as shown in FIG. 8(b), and a voltage VC as shown in FIG. 8(c) is generated from the terminal C. In other words, this oscillator OS
2, a pulse voltage is generated as voltage VC from just before voltage VA falls until it falls, and a pulse voltage is generated as voltage VC from just before voltage VA rises until it rises.

In addition, as in the conventional example, the voltage VB2 is lower than the normal voltage during a predetermined period (until the lamp current reaches a predetermined level) after the fall and rise of the voltage VA shown in FIG. A voltage VB2 having a low value is generated. With the above configuration, in this discharge lamp lighting device, the accumulated charge in the capacitor C1 is transferred to the resistor R within a predetermined period immediately before the voltage VA falls and immediately before the voltage VA rises.
At this time, the lamp current IDL returns to zero, and after that, the gate voltages VQ1 and VQ2 with wide pulse widths are applied to the switching elements Q1 and Q2.
In addition to this, the lamp current IDL will rapidly fall or rise.

FIG. 9(a) shows the gate voltage VQ1 input from the drive circuit DR1 to the gate of the switching element Q1, and FIG. 9(b) shows the gate voltage VQ2 input from the drive circuit DR2 to the gate of the switching element Q2. 8(c) shows the control signal VSW applied to the switch SW, and this waveform is the same as the voltage VC in FIG. 8(c). The figure (d) shows the current IL1 flowing through the inductor L1, and the figure (e) shows the discharge lamp DL.
2 shows the lamp current IDL flowing through the lamp.

In FIG. 9, before time t0, period T2
, and the period after time t0 corresponds to period T1. Before time t0, the gate voltage VQ2 is supplied to the switching element Q2, and the switching element Q2 is repeatedly turned on and off, and after time t0, the switching element Q2 is supplied with the gate voltage VQ2.
The gate voltage VQ1 is supplied to the switching element Q1, and the switching element Q1 is repeatedly turned on and off.

When the switching element Q2 is repeatedly turned on and off, a negative current IL1 flows through the inductor L1.
(in FIG. 9, a downward current) flows, and when the switching element Q1 is repeatedly turned on and off, a positive current IL1 (in FIG. 9, an upward current) flows through the inductor L1. At this time, a negative lamp current IDL (downward current in FIG. 9) flows through the discharge lamp DL during a period T2, and a positive lamp current IDL (an upward current in FIG. 9) flows during a period T1.

At the time of transition from period T2 to period T1, that is, when lamp current IDL changes from negative polarity to positive polarity, switch SW is once turned on and capacitor C
After the charge of 1 is released, the pulse frequency of gate voltage VQ1 becomes lower and the pulse width becomes wider than normal, and after this, the pulse frequency of gate voltage VQ1 returns to its original state and the pulse width also returns to its original state. .

As a result, when transitioning from period T2 to period T1, that is, when lamp current IDL changes from negative polarity to positive polarity, first, by turning on switch SW, the accumulated charge in capacitor C1 is released. , after the accumulated charge in the capacitor C1 is released, the switching element Q1 is turned on and off with a wide pulse width, thereby rapidly raising the lamp current IDL.

[0041] Also, when transitioning from period T1 to period T2, similarly to the above, after turning on the switch SW once,
The pulse frequency of gate voltage VQ2 becomes lower and the pulse width becomes wider than normal, and then the pulse frequency of gate voltage VQ2 returns to its original state and the pulse width also returns to its original state. As a result, after the accumulated charge in the capacitor C1 is released, the lamp current IDL is rapidly reduced. In addition,
The period in which the switch SW is turned on is until the accumulated charge in the capacitor C1 is exhausted, and the period in which the pulse width is widened is until the lamp current IDL reaches a predetermined value.

This embodiment has the same effects as the first embodiment. Although FIG. 10 shows a discharge lamp lighting device that lights a high-pressure discharge lamp with a square wave using a full-bridge inverter, it goes without saying that the present invention can be applied to such a discharge lamp lighting device as well. That's true. In FIG. 10, Q11 to Q14 are switching elements, D11 to D14 are diodes, and these constitute a full bridge inverter IV2. L2 is an inductor.

[0043]

According to the discharge lamp lighting device of the present invention, the pulse voltage is controlled by the pulse control means at the time of transition from the first period to the second period and from the second period to the first period. The state is temporarily changed to make the lamp current of the discharge lamp rise and fall quickly when the polarity is reversed, so it is possible to suppress the generation of re-ignition voltage in the discharge lamp, and to reduce the flickering of the discharge lamp. It can be prevented.

Furthermore, before the state of the pulse voltage is changed by the pulse control means at the transition from the first period to the second period and from the second period to the first period, the accumulated charge releasing means Since the accumulated charge in the capacitor is released, it is possible to prevent the current caused by the accumulated charge in the capacitor from suddenly flowing into the inductor and switching element, and therefore, the peak value can be made to be the same as in normal times. The withstand capacity of the inductor and the switching element can be kept low, and the generation of noise can be reduced.

[Brief explanation of drawings]

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

FIG. 2 is a time chart showing the operation of the discharge lamp lighting device of FIG. 1;

FIG. 3 is a time chart showing the operation of the discharge lamp lighting device shown in FIG. 1;

FIG. 4 is a circuit diagram showing the configuration of a discharge lamp lighting device according to a second embodiment of the present invention.

FIG. 5 is a time chart showing the operation of the discharge lamp lighting device of FIG. 4;

6 is a time chart showing the operation of the discharge lamp lighting device shown in FIG. 4; FIG.

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

8 is a time chart showing the operation of the discharge lamp lighting device of FIG. 7. FIG.

9 is a time chart showing the operation of the discharge lamp lighting device similarly shown in FIG. 7. FIG.

FIG. 10 is a circuit diagram showing the configuration of a full-bridge discharge lamp lighting device.

FIG. 11 is a circuit diagram showing the configuration of a conventional example of a discharge lamp lighting device.

12 is a time chart showing the operation of the discharge lamp lighting device of FIG. 11. FIG.

13 is a time chart showing the operation of the discharge lamp lighting device similarly shown in FIG. 11. FIG.

[Explanation of symbols]

VDC DC power supply DL Discharge lamp L1 Inductor C1 Capacitor C2, C3 Capacitor Q1, Q2 Switching element DR1, D
R2 Drive circuit G1, G2 A
ND gate G3 Not gate OS1 Oscillator VF Voltage-frequency converter

Claims (1)

[Claims] 1. A discharge lamp having an inductor connected in series and a capacitor connected in parallel, a pulse voltage of a first polarity is repeatedly applied during a first period, and a pulse voltage of a second polarity is applied during a second period. an inverter that lights the discharge lamp with a rectangular wave by repeatedly applying the pulse voltage; pulse control means for temporarily changing the state of the lamp current of the discharge lamp to rapidly rise and fall at the time of polarity reversal; 2. A discharge lamp lighting device comprising: charge discharge means for discharging the charge accumulated in the capacitor before the pulse control means changes the state of the pulse voltage at the time of transition from period 2 to the first period.