JPS61171094A - High pressure discharge lamp lighting apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a high-pressure discharge lamp lighting device that takes measures against arc instability caused by an acoustic resonance phenomenon in high-frequency lighting.

[Background technology]

Figure 6 is a circuit diagram of a conventional steel type discharge lamp lighting device.
FIG. 7 is a waveform diagram of the power supply voltage and lamp current.

In Figure 6, E is an AC power supply, L is a choke coil,
1 and a are high pressure discharge lamps. In FIG. 7, vl is the voltage of the AC power source E, and I is the lamp current.

The lamp current IL is very smooth, and the high pressure discharge lamp La
There are no problems with the luminous efficiency or lifespan of the Chiroku Coil L.
Due to the presence of , the equipment becomes larger.

There is a problem with the weight.

High frequency lighting was developed as a method to solve this problem. It is generally above the audible frequency (e.g. 4
It lights up at 0KHz).

FIG. 8 is a principle circuit diagram of a conventional high-frequency lighting device, and FIG. 9 is a waveform diagram of its power supply voltage and lamp current.

In Figure 8, E is an AC power supply, DB+ is a full-wave rectifier,
t and o are choke coils, Try and Tr2 are transistors that turn on and off alternately, C is an oscillation capacitor, and OT
is an oscillation transformer, and La is a high-pressure discharge lamp.

In FIG. 9, the lamp current IL1, which is a high frequency current,
The envelope line of is shown by a broken line.

In the case of this high-frequency lighting device, since high-frequency lighting is performed, the power supply voltage V and the lamp current ILL are approximately similar. That is, there is no negative resistance characteristic as in the case of commercial lighting.

Therefore, the envelope of the waveform of the lamp current ILI approximates the lamp current in the case of resistance loading. Therefore, there are no problems with the luminous efficiency or lifespan of the high pressure discharge lamp La.
Also, choke coil t.

Since only a small capacity is required, the device can be made smaller and lighter.

Note that since the frequency of the full-wave rectified voltage is directly converted without connecting a smoothing capacitor after the full-wave rectifier DBI, the human power factor can be increased without increasing costs.

However, when the high-pressure discharge lamp La is lit at high frequencies above the audible frequency, an acoustic resonance phenomenon occurs and the arc becomes unstable, resulting in fatal problems such as "flickering" or extinguishing of the high-pressure discharge lamp La, and destruction of the arc tube. Defects are a problem.

The mechanism of arc instability that occurs during high-frequency lighting of the high-pressure discharge lamp is considered to be as follows.

That is, the mechanism is: (1) high-frequency fluctuations in electrical input; (0) pressure changes in the gas within the arc tube; (0) generation of standing pressure waves at special frequencies; and (2) occurrence of arc instability due to pressure amplitude exceeding the limit.

Here, the "special frequency" is a so-called acoustic resonance frequency, which is determined by the dimensionality of the arc (specifically, the shape of the arc tube) and the speed of sound inside the arc tube, and the speed of sound is , can be determined once the average molecular weight and ion temperature of the gas are determined, so once these values are known, the acoustic resonance frequency can be determined relatively easily.

However, due to "pressure amplitude exceeding the limit"
As for the acoustic resonance frequency at which J-arc instability occurs, it is a problem in a nonlinear domain, and a solution cannot be found simply.

Note that methods such as rectangular wave lighting and frequency limitation are known as measures to prevent arc instability due to acoustic resonance phenomena, but these are not sufficient.

The basis of this invention is a discharge lamp lighting device of a type developed to solve the problems of the various lighting methods described above.

That is, at least the lowest frequency at which an acoustic resonance phenomenon occurs at a frequency higher than the commercial power supply frequency (for example, in the case of a 250W mercury lamp (H2SO) manufactured by Matsushita Electronics Co., Ltd.,
Approximately 3.5KHz, 250W metal halide lamp manufactured by the same company
(M250 L/BU), approximately 3.0KHz
) If the following frequencies are used, the input power factor can be improved without increasing costs.

Taking advantage of this, there is a discharge lamp lighting device of a type that is configured to light a high-pressure discharge lamp using an inverter circuit that directly converts the commercial AC power frequency to the above-mentioned lighting frequency.

FIG. 1O shows an example of a discharge lamp lighting device that lights at a frequency lower than the lowest frequency at which the acoustic resonance phenomenon occurs. This is a conventional example that directly contrasts with this invention.

In FIG. 10, E is an AC power supply, DB is a full-wave rectifier, Q1 to Q4 are transistors, D, D2 are diodes, Ll is a choke coil, and La is a high-pressure discharge lamp.

A series circuit of transistors Q, , Q, and transistors Q2 . A series circuit of Q3 is connected.

Transistor Q1. The collector of Q2 is a full wave rectifier DB
, and their emitters are connected to the positive terminals of transistors Q4. Connected to the collector of Q3. Transistor Q4. The emitter of Q3 is connected to the fish type terminal of the full wave rectifier DB.

Transistors Q1-Q4 and diode DI.

D2 constitutes an inverter circuit In.

Diodes D1 . . . are connected to the collectors of transistors Q, , Q2, respectively. The cathode of D2 is connected, and the transistor Q,
, Q2 are connected to the emitters of diodes D1., Q2, respectively. The anode of D2 is connected.

The connection point between transistors Q, , Q4 and transistor Q2.
A series circuit of the choke coil 1 and the high pressure discharge lamp La is connected between the connection point of Q3.

FIG. 11 is a time chart of the discharge lamp lighting device of FIG. 10, and FIGS. (A) to (D) are transistor Q
1 to Q4, and Figure (E) shows the waveforms of the lamp electric current 1iLIL2.

From time 1 to t2, transistors Q, , Q3 are on, and transistors Q2 . Since Q is off, the full-wave rectifier D B , -1 - transistor Q1 - choke coil L
1-High pressure discharge lamp La-Transistor Q3-Full wave adjuster D
A lamp current IRI L2 flows in the closed loop of B, and this lamp current IL2 gradually increases.

When transistor Q3 turns off at time t2, time t1
The energy stored in the choke coil L between ~t2 is released in a closed loop of the choke coil 1 - high pressure discharge lamp La -> diode D2 - transistor 1 -> chituk coil L. Therefore, the lamp current 112 gradually decreases.

At the time (3) when the energy becomes zero, transistor Q1 is turned off and transistors Q2 and Q are turned on.

From time t3 to t4, transistor Q2. Since Q4 is on and transistors Q, , Q3 are off, the lamp current [L2 flows in the opposite direction from time t1 to t2, and this lamp current IL2 gradually increases.

When transistor Q4 turns off at time t4, time t3
The energy stored in the choke coil L1 between ~L4 is transferred to the choke coil LI-diode [),
−< ) Positive number light on transistor Q 2 =
JLa - discharged in the closed loop of the choke coil L dish. Therefore, the lamp current IL2 gradually decreases.

At time t5 when the energy becomes zero, transistor Q2 is turned off, transistor Q1. Q3 is turned on.

Thereafter, the same operation is repeated, and the lamp current 1L2 exhibits a waveform as shown in FIG.

FIG. 12 shows the waveform of the lamp current IL2 using an AC type fAE.
The period of one cycle of the waveform of the voltage v1 is shown. Figure 0 (C), which shows the envelope of the lamp current IL2 with a broken line, is the current input from the full-wave rectifier DB to the inverter circuit In! 0 waveform is shown, and the envelope of the input current 1 o is shown as a dashed line.

The conventional example shown in FIG. 10 has the following problems.

As can be seen from the comparison between (A) and (B) in Figure 12,
The current value is small in the first half of the half-wave of power supply voltage 1, and the waveform has a peak in the second half of the half-wave.

The lamp current IL2 having such a waveform has a high crest factor,
Therefore, the life of the discharge lamp is short and the luminous efficiency is poor.

Furthermore, at the time when the lamp current fltIL2 reaches its peak, transistors Q, , Q3 or transistor Q
It is necessary to flow a sufficiently large base drive current with respect to 2+Q4, which increases the capacity and size of the Haas drive portion and increases cost.

Moreover, as can be seen from FIG. 12(C), the input current 1. Also, the current value is small in the first half of the half-wave of the power supply voltage v1, and the waveform has a peak in the second half of the half-wave, and the crest factor is high, so the input power factor is poor.

(Object of the Invention) The object of the present invention is to solve the above-mentioned problems and to light a high-pressure discharge lamp by using a pulsating voltage obtained by full-wave rectification of the output of a commercial AC power supply through an inverter circuit. It is an object of the present invention to provide a high-pressure discharge lamp lighting device that not only prevents instability of the arc due to a resonance phenomenon but also has a high lighting efficiency, a long life, and a high input power factor.

[Disclosure of the invention]

The high-pressure discharge lamp lighting device of the present invention includes a DC power supply that full-wave rectifies an AC voltage, and a discharge terminal connected to the output terminal of the DC power supply to change the frequency of the output voltage of the DC power supply by the acoustic resonance phenomenon of the high-pressure discharge lamp. an inverter circuit that converts the frequency to a lower frequency than the lowest frequency at which instability occurs; a series circuit of a high-pressure discharge lamp and its current limiting element connected to the output end of the inverter circuit; It is equipped with a control circuit that controls the output voltage of the DC power source to be low in a low region and high in a high region.

According to the configuration of this invention, the following effects are achieved.

ta+ The pulsating voltage obtained by full-wave rectification of the AC power supply output is converted by an inverter circuit to a frequency lower than the frequency at which arc instability occurs due to acoustic resonance phenomenon, and the high-pressure discharge lamp is lit. can be prevented.

(b) Since it is equipped with a control circuit that controls the output frequency of the inverter circuit to be low in the low output voltage range of the DC power supply and high in the high range, the discharge lamp current is covered by the first half and the second half of the half-wave of the power supply voltage. The route will be almost symmetrical.

Therefore, the peak value of the discharge lamp current can be made smaller than that of the conventional example even though the effective value is the same, and the short life of the discharge lamp and the poor luminous efficiency caused by the poor crest factor observed in the conventional example are solved.

fcl Furthermore, the peak value of the discharge lamp current is reduced, and the drive current to be passed through the switching elements of the inverter circuit is small, making it possible to reduce the capacity, size, and cost of the drive' portion.

+d+ Moreover, the crest factor of the input current to the inverter circuit is improved, and the human power factor is also improved.

Embodiment A first embodiment of the present invention will be described with reference to FIGS. 1 to 3. Figure 1 is a circuit diagram of the high-pressure discharge lamp lighting device, Figure 2 is its time chart, and Figure 3 is a waveform diagram for explaining the operation.
J In these figures, the same symbols used in FIG. and the conventional example have the same configuration.

The structure in which this embodiment differs from the conventional example shown in FIG. 10 is as follows.

A lamp current detecting resistor R1 is interposed between the anode of the diode D1 and the choke coil LL, and a primary winding i1N+ of a lamp current detecting transformer T is connected between both ends thereof.

A full-wave rectifier DB2 is connected between both ends of the secondary winding N2 of the lamp current detection transformer T, and a base drive stop circuit P2 is connected to the output end of the full-wave rectifier DB2.

Emitter of transistor Q4 and full wave rectifier DB.

A resistor R2 is inserted between the negative terminal of the full-wave rectifier DB and the input current to the inverter circuit In, and thus the lamp current IL3, and a lamp current maximum value detection circuit is inserted between both ends of this resistor R2. P1 is connected.

P3 is an inverter circuit control circuit connected to the lamp current maximum value detection circuit P1 and the base drive stop circuit P2.

These lamp current maximum value detection circuit P1 and its related circuits, base drive stop circuit P2 and its related circuits, and inverter circuit control circuit P3 are arranged so that the output frequency of the inverter circuit can be adjusted to This is an example of a control circuit ConJ that controls the voltage to be low in a low region and high in a high region.

The lamp current maximum value detection circuit P1 compares the voltage corresponding to the instantaneous value of the input terminal detected by the resistor R2 with a reference voltage,
When the voltage corresponding to the instantaneous value of the input current reaches the reference voltage, a signal for stopping the base drive of the transistor Q3 or the transistor Q4 is output to the inverter circuit control circuit P3.

The base drive stop circuit P2 includes a lamp current detection resistor R and a lamp current detection transformer T.

Lamp current 111 inputted at
When EIt3 becomes zero, transistor Q1 or transistor Q is connected to inverter circuit control circuit P3.
This outputs a signal for stopping the base drive of No. 2.

The inverter circuit control circuit P3 controls the transistors Q and -Q4 of the inverter circuit In as follows. That is, for all the transistors Q1 to Q4, the start point of their on-period is the point in time when the base drive stop circuit P2 detects zero of the lamp current L3. Further, the transistors Q, Q2 are controlled to be turned on and off alternately, and the transistors Q3 + Q4 are controlled to be turned on and off alternately. Furthermore, transistor Q1. The on periods of transistors Q3 overlap, and transistors Q2. Control is performed so that the on periods of Q4 overlap.

Further, the inverter circuit control circuit P3 includes an internal timer, and transistors Q3. After transistor Q4 is turned on, transistor Q3. If the base drive stop signal of transistor Q3 is not input, the transistor Q3. Q.

This automatically stops the base drive.

The rest of the configuration is the same as that of the conventional example shown in FIG. 1θ, so a description thereof will be omitted.

Next, the operation will be explained based on FIG.

Figure (A) shows the power supply voltage v1, and Figure (B) shows the lamp current 11.
3, and Figures (C) to (F) are transistors Q1 to Q1, respectively.
The operation of Q4 is shown.

■ Reference current in figure (B) +1. , -1. , the lamp current IL3 is this reference current +1. , -1m is detected by the lamp current maximum value detection circuit Pl, and the transistor Q3. This is for outputting a base drive stop signal for Q4 to the inverter circuit control circuit P3.

■ Time at the beginning of power supply voltage v1 t ll' = t 12
In this case, transistors Q, , Q3 are on, and lamp current IL3 gradually increases in the positive direction. However, the transistor Q3 set inside the inverter circuit control circuit P3
．． The point in time when the longest ON period T of Q has elapsed
By time t12, which is J, the lamp current IL3 increases to the reference current +1. Since the transistor Q3 has not reached
turns off at time t12 when the longest on period T has elapsed.

(2) The energy accumulated in the choke coil L1 during the period from time t11 to t12 is transferred to the high pressure discharge lamp La, the diode D2, . Transistor Q1
The lamp current IL3 gradually decreases in the positive direction. Then, at time t13 when the lamp current IL3 crosses zero, the pace drive stop circuit P2 detects this and turns off the transistor Q1 via the inverter circuit control circuit P3.

■ At time t13 when transistor Q1 is turned off, transistor Q2. Q is turned on, and a lamp current 113 flows through the high-pressure discharge lamp La in the opposite direction (negative direction) to that at time tll""112. In this case, since the power supply voltage v1 is higher than at times t41 to t12, the slope of the lamp current IL3, which gradually increases in the negative direction, is also increased.

Therefore, the lamp current 113 reaches the reference current -1m at time t14, and the lamp current maximum value detection circuit P detects this and turns off the transistor Q4 via the inverter circuit control circuit P3.

(2) The energy accumulated in the choke coil L1 during the period from time t13 to t14 is transferred to the diode D1. Transistor Q2. high pressure discharge lamp la
The lamp m current IL3 gradually decreases in the negative direction. Then, at time t+5 when the lamp current IL3 crosses zero, the straight drive stop circuit P2 detects this and turns off the transistor Q2 via the inverter circuit control circuit P3.

(2) At time t15 when the transistor Q2 is turned off, the transistors Ql and Q3 are turned on, and a lamp current IL3 flows in the positive direction through the high-pressure discharge lamp La.

In this case as well, since the power supply voltage 1 is high, the slope of the gradually increasing lamp current fLI13 is also large.

Lamp current lL3 becomes reference current +li at time t16
The lamp current maximum value detection circuit P1 detects this and turns off the transistor Q3 via the inverter circuit control circuit P3.

■ From then on, repeat the same operation until time tl? ~til
Enter period l. During this period, transistor Q2
+Q4 is on, and the lamp voltage fil+,:+ gradually increases in the negative direction.

However, in this period, since the power supply voltage V is low, the lamp current 113 does not reach the reference current -11, so the transistor Q4 is turned on at time th, which is the point in time when the longest on period T has elapsed.
It turns off at e.

■ Time Ll? The energy accumulated in the chiller coil L1 during the period from the to t18 is transferred to the diode D+, the transistor Q2, . High pressure discharge lamp La
7. The lamp current 113 gradually decreases in the negative direction. Then, at time t19 when the lamp current IL3 crosses zero, the base drive stop circuit P2 detects this and turns off the transistor Q2 via the inverter circuit control circuit P3.

Figure 3 shows the waveform of the lamp current IL3 of the AC type 1llE.
The period of one cycle of the waveform of the voltage Vi is shown. The envelope of the lamp current ILI is shown by a dashed line. Figure (C) shows the waveform of the current ■1 input from the full-wave rectifier DB to the inverter circuit In, and the input current 1. The envelope of is shown as a dashed line.

As can be seen from the comparison between (A) and (B) in FIG. 3, the envelope lines of the lamp current IL3 are almost symmetrical in the first half and the second half of the half wave of the power supply voltage v1. This and Figure 12 (
Comparing B), the peak value of the lamp current ■L3 is smaller even though the effective value is the same, and the life of the discharge lamp is shortened due to the poor crest factor seen in the conventional example shown in Figure 10. and the problem of poor luminous efficiency has been resolved.

Furthermore, since the peak value of lamp current IL3 is small, transistors Q, , Q3 or transistors Q2... Q4
The base drive current applied to the base drive can be reduced, and the base drive part can be made smaller and smaller.
It is possible to reduce costs.

Moreover, as can be seen from FIG. 3(C), the crest factor of the input current 11 is also improved, and the input power factor can also be improved.

From the above, it is clear that according to this embodiment, the effects of the configuration of the invention described above can be obtained.

A second embodiment will be explained based on FIG. 4. FIG. 4 is a time chart of the high-pressure discharge lamp lighting device. FIG. 8 (A) shows the power supply voltage (1), and FIGS. (B) to (E) show the operations of the transistors Q1 to Q4, respectively.

The circuit of the high pressure discharge lamp lighting device of this embodiment is the lamp current maximum value detection circuit P in the circuit of FIG.

and its related circuits, and the circuit is the same as that of FIG. 1 except for the base drive stop circuit P2 and its related circuits.

However, regarding the control of the transistors Q and -Q4, a control form different from that of the first embodiment is adopted.

That is, in the case of the first embodiment, the on-timings of transistors Q, . The off timing of Q is determined by the lamp current IL3 as the reference current +r, .
, -11, and transistors Q, ,Q
The off timing of No. 2 is set at the time when the lamp current 113 crosses zero.

Therefore, two elements, the lamp current maximum value detection circuit P1 and the base drive stop circuit P2, are required as circuit state detection elements, making the circuit configuration a little complicated.

In contrast, in the case of the second embodiment, the switching modes of the transistors Q1 to Q4 are set in advance so that the peak value of the lamp current is approximately constant.

That is, the on period of each of the transistors Q1 to Q4 is made longer in the region where the power supply voltage ■1 is low, and
By setting the lamp current to be short in a region where the current is high, the peak value of the lamp current is kept almost constant.

Therefore, two elements, the lamp current maximum value detection circuit P1 and the base drive stop circuit P2, as in the case of the first embodiment, become unnecessary, and the circuit configuration is simplified.

A third embodiment will be explained based on FIG. FIG. 5 is a circuit diagram of the high pressure discharge lamp lighting device.

In FIG. 5, the same reference numerals used in FIG. 1 according to the first embodiment refer to the same parts as those indicated by the reference numerals. Regarding connections, unless otherwise specified,
This embodiment has the same configuration as the first embodiment.

The configurations in which this embodiment differs from the first embodiment are as follows.

There is no base drive stop circuit P2 and its related circuits in the first embodiment, but instead a full wave rectifier DB
A capacitor C1 is connected across the output of , and
Transistor Q3. The point is that diodes D3 and D4 are connected between the emitter and collector of Q4, respectively.

Capacitor CI is a bypass capacitor for discharging the energy stored in choke coil 1, and full-wave rectifier DB
The transistors Ql and Q are not intended to smooth the output of
3 are turned off and on at the same time, and transistors Q2. Q4 turns off and on at the same time.

Also, transistors Q, , Q3 and transistors Q2 . Q
, and alternately turn on and off with each other.

That is, when the transistors Q, Q3 are switched from on to off, the energy stored in the choke coil L, - the diode D.

- Capacitor C1 - Diode D3 - High pressure discharge lamp La -
It is released in the closed loop circuit of the choke coil L.

Also, transistor Q2. When Q4 is switched from on to off, the energy stored in the choke coil L1 is released in a closed loop circuit of choke coil L1 - high pressure discharge lamp La - diode D2 -> capacitor C1 - diode D4 - choke coil S1.

In other words, the control of transistors Q and -Q4 is as follows:
J transistor Q1. Q3 and transistor Q2. It suffices to simply turn Q4 on and off alternately, and the circuit configuration is simplified compared to the first embodiment. That is, transistor Q1. Q2
It is sufficient to provide only the lamp current maximum value detection circuit P and its related circuits without considering the off-timing of the lamp current.

〔Effect of the invention〕

According to this invention, the following effects are achieved.

It is equipped with a control circuit that controls the output frequency of the inverter circuit to be low in the low output voltage range of the DC power supply and high in the high range, so that the envelope of the discharge lamp current can be adjusted in the first and second half of the half-wave of the power supply voltage. It can be made almost symmetrical,
Although the effective value is the same, the peak value of the discharge lamp current can be made smaller than that of the conventional example, the crest factor can be improved, and the life of the discharge lamp can be extended and the luminous efficiency can be improved.

Furthermore, the peak value of the discharge lamp current is reduced, and the drive current flowing through the switching elements of the inverter circuit can be small, making it possible to reduce the capacity, size, and cost of the drive portion.

IcI Furthermore, the crest factor and input power factor of the input terminal to the inverter circuit can also be improved.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of a high-pressure discharge lamp lighting device according to a first embodiment of the present invention, FIG. 2 is a time chart thereof, FIG. 3 is a waveform diagram for explaining the operation, and FIG. 4 is a diagram of a second embodiment. The time chart of the example high-pressure discharge lamp lighting device, Fig. 5 is the circuit diagram of the third embodiment, Fig. 6 is the circuit diagram of the conventional steel type discharge lamp lighting device, and Fig. 7 is the power supply voltage and lamp. Current waveform diagram,
Figure 8 is a basic circuit diagram of a conventional high-frequency lighting device, Figure 9 is a waveform diagram of its power supply voltage and lamp current, and Figure 10 is a diagram of a method for lighting at a frequency lower than the lowest frequency at which acoustic resonance occurs. FIG. 11 is a circuit diagram of an example of a discharge lamp lighting device; FIG. 11 is a time chart thereof; FIG. 12 is a waveform diagram of AC voltage, lamp current, and input terminals. E...AC power supply, DB,...full wave rectifier, In...
・Inverter circuit, l-a...high pressure discharge lamp, LI...
・Choke coil (current limiting element), Con... Control circuit Con #Ier@% -N (Q %t > (5C$CIC$1)

Claims (1)

[Claims] A DC power supply that performs full-wave rectification of AC voltage is connected to the output terminal of this DC power supply, and the frequency of the output voltage of this DC power supply is lower than the lowest frequency at which discharge instability occurs due to the acoustic resonance phenomenon of high-pressure discharge lamps. an inverter circuit that converts the frequency into a high-pressure discharge lamp connected to the output end of the inverter circuit, and a series circuit of a current-limiting element thereof; A high-pressure discharge lamp lighting device equipped with a high-control control circuit.