JPH0279398A - Electric discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To permit a proper lamp current to flow through each electric discharge lamp by controlling each lamp current for each electric discharge lamp by means of a switching element provided for each one. CONSTITUTION:Switching elements Q1 to Q4 are put into operation as switching elements for switching the polarity of lamp currents IDL1, IDL2 flowing through electric discharge lamps DL1, DL2 and therewith switching elements Q7, Q8 for high-frequency switching are added for use in current control of two electric discharge lamps DL1, DL2. The lamp currents IDL1, IDL2 flowing through the electric discharge lamps DL1, DL2, respectively, are here detected by current transformers CT1, CT2 and corresponding to the detecting amount a control circuit portion X2 controls the switching elements Q7, Q8. The lamp current can be thus controlled corresponding to each of the electric discharge lamps even if they have different properties.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a discharge lamp lighting device for lighting a discharge lamp such as a high-pressure discharge lamp.

[Prior art] Fig. 6 shows a circuit diagram of a discharge lamp lighting device including a full-bridge inverter circuit, which is the basis of the present invention, and Fig. 7 shows a specific circuit of the main part of Fig. 6. The figure shows.

The discharge lamp lighting device shown in FIG. 6 consists of a DC power supply E1, a discharge lamp DL such as a high-pressure discharge lamp, a series circuit of an inductance element L2, a parallel circuit of a capacitance element C2 consisting of a capacitor, an inductance element L+, and a transistor. The switching elements Q, ,Q, are connected in series to form a first closed circuit that allows current to flow in one direction through the discharge lamp DL1, and the discharge lamp DL+ and the inductance element L2 are connected in series to the DC power source E. Circuit and capacitance element C
A switching element Q2 consisting of two parallel circuits, an inductance element, and a transistor. Q3 is connected in series to form a second closed circuit that allows current to flow in the other direction through the discharge lamp DL. Furthermore, each cycle of the low frequency is divided into a first and a second operating period, and a pause is provided between the first operating period and the second operating period and between the second operating period and the first operating period, respectively. period, the switching element Q1 is turned on and off at high frequency during the first operation period, the switching element Q2 is held off, and the switching element Q3 . During the second operating period, the switching element Q2 is turned on and off at high frequency, and the switching elements (h, Q- are held on and off, respectively. During the rest period, the switching element Q, ,Q2.C3,Q
, a control port 128Xl (details shown in FIG. 7) is provided to keep all of the .

In Fig. 6, ■1 is an AC power supply, D B + is a full-wave rectifier, CI is a smoothing capacitor, and these are the DC power supply E.
1. The main inductance element L2 constitutes a filter circuit together with the capacitance element C2. Further D
1 to 3 are diodes, respectively, and R3 is a current detection resistor.

In FIG. 7, T1 is a transformer, T2 and T.

are each a pulse transformer, DB2 is a full-wave rectifier, C3 to C6 are each a capacitor, and R2 to R15 are each a resistor R3.
, are resistors, Ds and Da are transistors, IC,
is a general-purpose switching regulator control integrated circuit (IR
3MO2N, manufactured by Sharp Corporation), IC2 is a general-purpose timer integrated circuit (LB8555M).

Manufactured by Tokyo Sanyo Electric Co., Ltd.), IC3 is a flip-flop (
4013; Manufactured by Matsushita Electronic Components Co., Ltd.), IC.

IC, is a NOR gate. Note that the symbols a to m in Fig. 7
correspond to the symbols a to m in the control circuit x1 in FIG. 6, respectively.

Next, the operation of the discharge lamp lighting device shown in FIGS. 6 and 7 will be explained with reference to FIG. 8.

In this discharge lamp lighting device, the switching elements Q, , Q2 are operated at a high frequency (for example, 400
Hz).

In this case, switching element Q is off as shown in FIG. 8(c);

is on as shown in FIG. 8(d), the switching element Q is turned on and off at high frequency as shown in FIG. 8(a), and the switching element Q2 is turned on as shown in FIG.
The off state is maintained as shown in Figure (b). On the other hand, the switching element Q3 is on as shown in FIG. 8(C),
When the switching element Q1 is off as shown in FIG. 8(d), the switching element Q1 is off as shown in FIG. 8(a).
), the off state is maintained, and the switching element Q2 turns on and off at high frequency as shown in FIG. 8(b).

Also, switching element Q3. Q, both of which are shown in Figure 8 (c
), (d), both switching elements Q, , Q2 are off as shown in FIG. 8(a).

Hold off as shown in (b). Note that the high frequency switching pulse width of the switching elements Q, . . . Q2 is determined by the current flowing through the switching elements Q, .

In the on/off operation of each of the switching elements Q1 to Q4 as described above, the switching elements Q, , Q.

Assuming that is on, a gradually increasing current flows through the resistor R1 due to the action of the inductance element, and this current generates a voltage across the resistor R1. input to the terminal, general-purpose switching regulator control integrated circuit I
The signal is amplified by an error amplifier (operational amplifier) built in C.

On the other hand, integrated circuit I for general-purpose switching regulator control
C, contains an oscillator that generates a sawtooth wave at a period set by a resistor R2 and a capacitor C4 connected to terminals 6 and 5, respectively, and a comparator for pulse width modulation. The output voltage of the amplifier and the sawtooth wave voltage output from the oscillator will be compared by a pulse width modulation comparator. As a result, a high-frequency pulse signal (for example, 40KH2) whose pulse width is modulated in accordance with the voltage across the resistor R from the pulse width modulation comparator is output from the No. 8 terminal of the general-purpose switching regulator control integrated circuit IC. The switching element Q1 is switched by the high frequency pulse signal, and the gradually increasing current is interrupted.

On the other hand, the length of the high-level pulse period Tp (corresponding to the above-mentioned operation period) of the low-frequency pulse signal (for example, 400 2) for turning on and off the switching element Q4 is as follows:
It is determined by the discharge time constant of resistor R14, capacitor C5, and resistor R15 connected to general-purpose timer integrated circuit IC2.

Then, the above-mentioned low frequency pulse signal is outputted from the third terminal of the general-purpose timer integrated circuit IC2.

The above low frequency pulse signal is applied to the flip-flop IC3, N
The output signals are distributed to terminals e and f by AND gates IC6 and IC, and are applied from terminals e and f to the bases of transistors that are switching elements Q, , Q, respectively. As a result, the switching elements Q, , Q, are turned on and off according to the low frequency pulse signal as described above as shown in FIGS. 8(c) and 8(d).

On the other hand, an integrated circuit IC for general-purpose switching regulator control
The high frequency pulse signal outputted from the No. 8 terminal of , is the output signal Q of the flip 70 tube IC3.

It is input to the NOR gate IC<, ICs along with Q, and N
The outputs of OR gates IC4 and IC5 are connected to transistors Q5.
Q, and pulse transformer T2. T, etc. to the base of the transistor which is the switching element Q, , Q2. Therefore, as mentioned above, the switching element Q,
, Q, are turned off and on during the pulse period Tp, as shown in FIGS. 8(a) and 8(b), the switching element Q turns on and off at high frequency, and the switching element Q2 maintains the off state. become. Also, during the pulse rest period Tl1l when both the switching elements Q, , Q4 are off, the switching elements Q, , Q2
Both hold off.

The discharge lamp lighting device shown in FIGS. 6 and 7 operates as described above, and currents as shown in FIGS. 8(e) and 8(f) flow through the switching elements Q1 and Q, respectively. The lamp current of the discharge lamp D L , due to the filtering action of the capacitance element C2 and the inductance element L2. L and the lamp voltage V of the discharge lamp DL. 1. is shown in Figure 8 (g>,
As shown in <1]), both have a substantially rectangular wave shape.

This discharge lamp lighting device has a pulse rest period T. By shortening, when the discharge lamp DL is lit, the discharge lamp D
L, lamp voltage V. A so-called high restriking voltage does not appear in the discharge lamp DL.

It has the advantage that it is extremely difficult to disappear.

In the discharge lamp lighting device shown in FIGS. 6 to 8 above, when lighting two discharge lamps, for example, as shown in FIG. 9, an inductance element is connected in parallel to the output terminal.7. L2, discharge lamp D
L, a series circuit composed of a capacitance element C2, and an inductance element L3. A possible method is to connect the discharge lamp DL2, the discharge lamp DL2, and the capacitance element C7 in a series circuit.

[Problem to be solved by the invention] However, if one lamp is lit as shown in Fig. 6, the discharge lamp D
Due to the resistance R5, the discharge lamp DL,
The current was controlled by detecting the current of the switching elements Q, Q2 and changing the switching duty of the switching elements Q, Q2, but when lighting two lamps as shown in Fig. 9, the discharge lamp DL and the discharge lamp DL
It is not possible to individually control the currents of both.

Therefore, if you want to control the current of the discharge lamps DL and DL2 individually, you will have to configure another bridge inverter circuit for the discharge lamp DL2 instead of lighting the two lamps in parallel as shown in Figure 9. However, there is a problem that the number of parts increases.

The present invention has been made in view of the above-mentioned problems, and its purpose is to provide a discharge lamp lighting device which has a simple structure and eliminates the disadvantages of lighting two lamps as described above. .

[Means for Solving the Problems] The present invention connects a series circuit of a first switching element and a second switching element between output terminals of a DC power supply, and connects a series circuit of a third switching element and a fourth switching element. A series circuit is connected between the first switching element and the second switching element.
A series circuit consisting of at least a discharge lamp and an inductance element is connected between a connection point with the first switching element and a connection point between the third switching element and the fourth switching element, and the first switching element A circuit including a discharge lamp, an inductance element, and a fourth switching element to flow a lamp current to the discharge lamp, and a circuit including a third switching element, a discharge lamp, an inductance element, and a fourth switching element to produce a discharge lamp. In a discharge lamp lighting device that controls a switching element so as to alternately form circuits that flow a lamp current at a low frequency and intermittent the lamp current at a high frequency, a plurality of discharge lamps are connected between the connection points. At the same time, a switching element is inserted in series in the lamp current supply path of each discharge lamp to detect the lamp current flowing through each discharge lamp and control each lamp current individually according to the detected amount. This is what I did.

In particular, in the invention according to claim 2, a fifth switching element is connected in series between the first switching element and the second switching element, and a sixth switching element is connected in series between the third switching element and the fourth switching element. switching elements are connected in series, and at least a first discharge lamp is connected between a connection point between the first switching element and the fifth switching element and a connection point between the third switching element and the sixth switching element. A series circuit consisting of the first inductance element and the first inductance element is connected, and at least A fifth circuit connects a series circuit consisting of a second discharge lamp and a second inductance element, detects the lamp current flowing through each discharge lamp, and controls each lamp current separately according to the detected amount. ,
The switching of the sixth switching element is controlled.

[Accordingly, in the present invention, a switching element is provided that corresponds to the lamp current of each discharge lamp, more specifically, in claim 2.
As in the invention described in Section 5. A sixth switching element controls the respective lamp current. Therefore, even if the characteristics of each discharge lamp are different, the lamp current can be controlled to suit each discharge lamp.

[Example] The present invention will be explained below with reference to Examples.

FIG. 1 shows an example circuit, and this example basically connects the switching elements Q, ~Q4 of the circuit of FIG. 6 to the discharge lamp D.
L,, Lamp current work that does not flow to DL2.

Ll l T operates as a switching element to change the polarity of DL2, and two discharge lamps DL,
.

Switching elements Q, Qa for high frequency switching are added for current control of DL2, and the discharge lamp DL
,, Lamp current flowing through DL2, respectively ■DLI, ID
t,2 is detected by the current transformers CT, CT2, and depending on the detected amount, the control circuit section X switches the switching element Q7. It is designed to control Qs.

The control circuit section X2 is composed of a circuit as shown in FIG.

In FIGS. 1 and 2, circuit components that are the same as those in FIGS. 6 and 7 are given the same symbols.
Descriptions of components that perform similar operations will be omitted. Also the first
Terminals a to h in the figure correspond to terminals a to h in FIG. 2.

Next, the operation of the embodiment circuit shown in FIG. 1 will be explained based on the operation waveform diagram shown in FIG.

First, switching elements Q1, Q, consisting of transistors,
and Q7. As shown in FIGS. 3(a) and (b), Q is alternately turned on and off at a low frequency (for example, 4001(z). On the other hand, switching elements Q7 and Q8 consisting of transistors are switched on and off at low frequencies (for example, 4001(z)) as shown in FIGS. ) as shown in the discharge lamps DL,,DL
Current transformer CTI, CT2 that detects the current flowing in
It turns on and off at high frequency while changing the on-duty according to the detected amount.

When the switching elements Q, Q4 are on, the discharge lamp DL,
There is a switching element Q, → an inductance element, →
Inductance element L2→discharge lamp DL.

A current flows in the path of → switching element Q8 → current transformer CT, → switching element Q4, and the lamp current I[)Ll of the discharge lamp DL is controlled by the switching element Q8.

Similarly, in the discharge lamp DL2, a current flows through the path of the switching element Q, → switching element Q7 → current transformer CT2 → inductance element L3 → inductance element → discharge lamp DL2 → switching element Q4, and the current flows through the discharge lamp DL2.
The lamp current I DL2 is controlled by the switching element Q7.

On the other hand, switching element Q2. When Q3 is on, current flows in both the discharge lamps DL, DL2 in the opposite direction to that in the above case, and the current control of the discharge lamp DL+ is controlled by the switching element Q.
.

The diodes D1-D4 and D7-D1o act as an inductance element I- during the ON period of the switching element Q7+Qs.
1, the energy stored in L3 is transferred to the switching element Q
7. The inductance element L 2 during the off period of Qa,
L4 constitutes a closed circuit for discharging via the discharge lamps DL, DL2.

Note that FIGS. 3(e) and 3(f) show a switching element Q7. made of a transistor. Collector current Io7+ of Q8
Waveforms of IQ@, (g) and (h) of the same figure are discharge lamp DL.

The lamp currents I11'Ll and ITIL2 of DL2 are shown, respectively.

The control circuit section x2 includes a general-purpose switching regulator control integrated circuit IC that operates in the same manner as the circuit shown in FIG. 7, and this general-purpose switching regulator control integrated circuit IC.
A general-purpose switching regulator control integrated circuit ICe similar to , is provided, and the general-purpose switching regulator control integrated circuit ■C1 controls the on-off duty according to the detected current amount of the current transformer CT2.
The transistor Q5 is driven by the high frequency signal outputted from the No. 8 terminal, and a driving signal for the switching element Q7 is outputted to the terminal m via the pulse transformer T2 and the resistor R1o.

Also, integrated circuit IC for general-purpose switching regulator control.
, controls the on/off duty according to the amount of current detected by the current transformer CT, and drives the transistor Q6 with the high frequency signal output from the No. 8 terminal, and connects the terminal L, through the pulse transformer T3 and the resistor R11. A drive signal for the switching element Q8 is output to n.

General-purpose timer integrated circuit IC2, flip-flop IC3
, NAND gates IC, , IC7 are passed through terminals e and f to switching elements Q3. Q
, and is further transmitted through resistors R22 and R23 to transistors Q9. Q, , is driven, and the pulse transformer T
4. A drive signal for the switching element Q1 synchronized with the switching element Q4 is output to the terminals g and i through the resistor R2, and the pulse transformer T9. A drive signal for the switching element Q2 synchronized with the switching element Q is output to the terminal i through the resistor R2S.

Note that the resistors R3 and R2 correspond to the resistors R2 to R7, and the capacitor C6 corresponds to the capacitor C1. In addition, the diode D and 1°DI2 are connected to the pulse transformer T4. This is a T5 back electromotive voltage absorbing diode.

By the way, in the above embodiment, the switching element Q++Q2 is switched at a low frequency, but the switching element Q
, ,Q may be operated at high frequency only during the on period. Fourth
The figure shows the circuit of the control circuit section X2 used in this case, and in this circuit, a general-purpose switching regulator control integrated circuit IC similar to the general-purpose switching regulator control integrated circuit C1, ICs, is further provided. A high frequency signal output from the No. 8 terminal of this general-purpose switching regulator control integrated circuit IC causes transistor Q to pass through NOR gates IC4 and IC5.

By driving Q + o, the switching element Q
1. A high-frequency drive signal synchronized with the on period of Q is
Generated from the i terminal, the j terminal, and the switching element Q
,, Q2 is switched at high frequency. FIG. 5(a) to (d) show switching elements Q1 to Q.
4 switching states are shown.

In the above embodiment, two lamps are lit in parallel, but the number of lamps is not limited to two, and even in the case of series lighting, it is sufficient to switch the lamp current supply path to each discharge lamp. Of course.

[Effects of the Invention] As described above, the present invention provides a switching element which is provided to control the lamp current of each discharge lamp respectively, and in particular, in the invention according to claim 2, the switching element is provided in a manner corresponding to the lamp current of each discharge lamp. Since each lamp current is controlled by the sixth switching element, even if the characteristics of each discharge lamp are different, the lamp current can be controlled according to each lamp. This has the effect that an appropriate lamp current can be passed through each discharge lamp, and the circuit configuration can be realized by simply adding a few circuit components to the basic full-bridge inverter circuit.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an embodiment of the present invention, Fig. 2 is a circuit diagram of an example of a control circuit used in the above, Fig. 3 is a waveform diagram for explaining the operation of the same, and Fig. 4 is used in the same. A circuit diagram of the other side of the control circuit section, FIG. 5 is a timing chart showing the switching states of the switching elements same as above, FIG. 6 is a circuit diagram of the discharge lamp lighting device which is the basis of the present invention, and FIG. 7 is a circuit diagram of the same as above. A circuit diagram of the control circuit section, FIG. 8 is a waveform diagram for explaining the operation of the same as above,
FIG. 9 is a circuit diagram of the main parts of the conventional example. DL,, DL2 are discharge lamps, Q1 to Q1, Q,, Q are switching elements, Ll to L4 are inductance elements, C
T, , CT2 is a current transformer, X2 is a control circuit section, E,
is a DC power supply. Agent Patent Attorney Ishi 1) Choshichi

Claims (2)

[Claims] (1) A series circuit of a first switching element and a second switching element is connected between the DC power supply output terminals, a series circuit of a third switching element and a fourth switching element is connected, and a series circuit of a third switching element and a fourth switching element is connected between A series circuit comprising at least a discharge lamp and an inductance element is connected between a connection point between the switching element and the second switching element and a connection point between the third switching element and the fourth switching element. , a circuit including a first switching element, a discharge lamp, an inductance element, and a fourth switching element to flow a lamp current to the discharge lamp; a third switching element, a discharge lamp, an inductance element, and a fourth switching element; In a discharge lamp lighting device that controls a switching element so as to alternately form a circuit for flowing a lamp current into a discharge lamp at a low frequency and to intermittent the lamp current at a high frequency, the lamp is connected between the above connection points. In addition to having multiple discharge lamps, a switching element is connected in series to the lamp current supply path of each discharge lamp to detect the lamp current flowing through each discharge lamp and control each lamp current separately according to the detected amount. A discharge lamp lighting device characterized by being inserted into a. (2) Connect a series circuit of the first switching element and the second switching element between the output terminals of the DC power supply, and connect a series circuit of the switching element and the fourth switching element shown in FIG. one switching element and a second switching element
A series circuit consisting of at least a discharge lamp and an inductance element is connected between a connection point with the first switching element and a connection point between the third switching element and the fourth switching element, and the first switching element A circuit including a discharge lamp, an inductance element, and a fourth switching element to flow a lamp current to the discharge lamp, and a circuit including a third switching element, a discharge lamp, an inductance element, and a fourth switching element to produce a discharge lamp. In a discharge lamp lighting device that controls a switching element so as to alternately form a circuit that flows a lamp current at a low frequency and to intermittent the lamp current at a high frequency, the first switching element and the second switching element are connected to each other. A fifth switching element is connected in series between the third switching element and the fourth switching element, a sixth switching element is connected in series between the first switching element and the fifth switching element, and a sixth switching element is connected in series between the third switching element and the fourth switching element. A series circuit including at least a first discharge lamp and a first inductance element is connected between the connection point and a connection point between the third switching element and the sixth switching element, and the fifth
A series circuit comprising at least a second discharge lamp and a second inductance element between the connection point between the switching element and the second switching element and the connection point between the sixth switching element and the fourth switching element. and detecting the lamp current flowing through each discharge lamp, and controlling the switching of the fifth and sixth switching elements so as to control each lamp current separately according to the detected amount. A discharge lamp lighting device characterized by: