JPS63237392A - Discharge lamp lighter - 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 discharge lamp lighting device that lights a plurality of discharge lamps in parallel at high frequency using a single-turn separately excited inverter circuit.

(Background technology) FIG. 6 is a circuit diagram of a conventional discharge lamp lighting device.

The power supply voltage of the alternating current power supply AC is rectified by the diode bridge DB, smoothed by the capacitor C0, and made into a direct current voltage. This DC voltage is applied to the series circuit of the primary side of the oscillation transformer OT and the transistor Trl.
・Discharge lamps DL, DL2 are connected in parallel to the secondary side of the lance OT via a capacitor C2 and a balancer T1.
An actance element (capacitor C) is attached to the non-power side of the discharge lamps DL, DL2.

C,) are connected to constitute a discharge lamp filament preheating circuit. A diode current is connected in antiparallel to the transistor TrI. Further, a capacitor C8 that exhibits a resonance state with the inductance component of the circuit is connected in parallel to both ends of the transistor Tr.

The capacitor CI may be connected to both ends of the primary coil of the oscillation transformer OT. transistor T
The output of the separately excited signal generating circuit 1 is inputted to the control pole of r+ via the drive circuit 3.

In the circuit shown in FIG. 6, when the two discharge lamps DL + and DL 2 are both lit, the balancer T1 performs the following:
The voltages induced in the windings 111 and 112 cancel each other out and have almost no inductance component, and when one of the discharge lamps is not lit, there is an inductance component due to the difference in the currents flowing through the windings nI and n2. This is what happens.

Figure 7 shows the operating waveforms of each part when two lamps are lit in such a configuration.
Base drive signal (“H”) to control on/off
The transistor Tr is activated by a separately excited ON signal, which indicates a separately excited ON signal (when it is at "High" level, it is called a separately excited ON signal, and when it is at a LOW" level, it is called a separately excited OFF signal).

When turned on, 5
, a current Ic as shown in FIG. 7(b) flows through the transistor Tr+. Transistor Tr with separately excited off signal
, is turned off, the oscillating transformer OT resonates with the capacitor C1 due to the energy stored in the LC component of the circuit, a resonant capacitor current flows, and the transistor Tr+
A resonant voltage as shown in FIG. 7(a) is generated at both ends of the line. When this resonant voltage becomes zero, the resonant current flows through the diode D1, and when the diode current becomes zero, the separately excited ON signal causes the transistor T'rl to flow.
As in the previous cycle, current Ic flows through (Fig. 7 (b)).
). In this way, oscillation continues, and the voltage generated on the secondary side of the oscillation transformer OT due to this resonance is applied to the discharge lamp via the leakage inductance of the oscillation transformer OT and the capacitor C2, thereby lighting the discharge lamp.

By the way, in the circuit configuration shown in Fig. 6, if one lamp is not lit due to some reason (for example, the life of the discharge lamp or connection uncertainty), the balancer T has an inductance component and As a result, the natural vibration period of the circuit becomes longer, and the width of the voltage vcε across the transistor Trl becomes wider. In this way, even if the natural oscillation period of the circuit becomes long when one lamp is not lit, in a separately excited inverter circuit, the transistor Tr will change according to the period of the separately excited signal.
In order to turn on the transistor Trl, the voltage V across the transistor Trl increases as shown in FIG. E, that is, the transistor Tr+ is turned on when the voltage of the resonant capacitor C1 is high, and the rush current from the capacitor C1 flows to the transistor Trl, causing a large power loss and also causing damage to the transistor Tr. Sometimes.

Therefore, in the circuit of FIG. 9, the transistor Tr.

An element voltage detection circuit 4 is provided to detect the voltage across the transistor Tr+, and when the voltage across the transistor Tr+ is high, the gate circuit 2 blocks passage of the separately excited ON signal and prohibits conduction of the transistor Trl. There is. Therefore, when one lamp is not lit, even if the width of the voltage VcE across the transistor Trl becomes longer as shown in FIG. 10(b), the period of VcB>O as shown in FIG. 10(e) By inhibiting the drive signal inside the transistor Tr+
conduction can be prohibited. The vcE detection signal ■ (Figure 10 (d)) is the vo5 detection signal ■ (Figure 10 (c)).
) is the inverted signal. The gate circuit 2 can be easily constituted by an AND gate that takes the logical result of this VcE detection signal (2) and the separately excited signal (FIG. 10 (a)).

By controlling in this manner, an increase in loss and destruction of the element due to a rush current flowing through the transistor Tr+ can be avoided. However, as can be seen by comparing the operating waveform when two lamps are lit (Figure 7) and the operating waveform when one lamp is lit (Figure 10), when two lamps are lit and when one lamp is lit,
The operating frequency is significantly different, and when one lamp is lit, the frequency is 1/2 compared to when two lamps are lit. Therefore, it becomes difficult to take noise prevention measures that reduce noise both when one lamp is turned on and when two lamps are turned on, and there is a problem in that the price of the device itself increases accordingly. Also,
For example, even if the frequency is set so that optical remote control interference does not occur when two lamps are turned on, optical remote control interference occurs when one lamp is turned on, which may cause malfunction of the optical remote control device.

Furthermore, in the operating waveform of FIG. 10, after the base drive signal (FIG. 10 (e)) of the transistor Tr output from the gate circuit 2 becomes "High" level, the collector current of the transistor Tr+ Ic (1st
For example, as shown in the operating waveform of FIG. 11, when the oscillating current is about to flow to the collector of the transistor Trl (time 1+), the transistor Tr+ turns on. If not, the operation of the inverter may stop and the discharge lamps may not turn on when one lamp is lit.

(Object of the invention) The present invention has been made in view of the above points, and
The purpose of this is to prevent undesired stress from being applied to semiconductor switch elements, etc., and to prevent the lighting frequency from changing significantly even if at least one of the multiple discharge lamps that are lit in parallel goes out. To provide a discharge lamp lighting device which avoids

(Disclosure of the Invention) The discharge lamp lighting device according to the present invention will be described with reference to the embodiment shown in FIG. A diode D connected in parallel to the transistor Tr+,
, an inductance element (primary side inductance of the oscillation transformer OT) connected in series with the transistor Tr, a resonant capacitor C1 that exhibits a resonance state with the inductance element, and a separately excited signal for repeatedly controlling the conduction of the transistor Tr. The period during which an oscillating voltage exists across the transistor Tr and the separately excited signal generating circuit 1 that generates the
A circuit (gate circuit 2) that prohibits a separately excited signal from being input to the base of the transistor Tr, and a plurality of parallel connections to which an oscillating voltage generated by turning on and off the transistor Trl is applied via a stabilizing element. discharge lamp DL
, DL2, the stability elements include a first stability element (leakage inductance of the oscillation transformer OT) for limiting the load current, and a second stability element (leakage inductance of the oscillation transformer OT) for connecting a plurality of discharge lamps in parallel. It consists of a balancer T, ),
The second stable element has almost no inductance when a plurality of discharge lamps are lit, and has a predetermined inductance value when at least one lamp is not lit. Even if at least one of the discharge lamps goes out, the transistor T
The generation period of the oscillating voltage at both ends of rl is 1 of the separately excited signal.
It is set to be shorter than the period.

In the conventional circuit shown in FIG. 9 described above, the reason why the lighting frequency changes greatly when one lamp goes out of operation is because the balancer T1 has an inductance component.
This is because the oscillation period of the circuit becomes longer, and the period during which the voltage VCε across the transistor Trl increases sinusoidally and returns to zero again becomes longer than one cycle of the separately excited signal.
The present invention is based on this point, and even if at least one of the plurality of discharge lamps goes out, the transistor T
The generation period of the oscillating voltage at both ends of r is 1 of the separately excited signal.
Balancer T so that it is shorter than the cycle.

By setting the inductance value of , it is possible to prevent the lighting frequency from changing significantly.

Examples of the present invention will be described below. Note that in the example circuit, the same elements as those in the conventional example circuit are given the same reference numerals and redundant explanations will be omitted.

Figure 1 is a circuit diagram of an embodiment of the present invention. The circuit configuration of FIG. 1 is the same as the conventional circuit shown in FIG. 9, but in the circuit of FIG. 1, even when one lamp is lit, the oscillation transformer OT, capacitors 01 to C2, discharge lamp DL, DL
, , and the generation period of the sinusoidal voltage applied to the transistor Tr+ is determined by the separately excited signal generating circuit 1 based on the vibration period determined by the inductance value of the balancer T1.
The inductance value of the balancer T1 is set so that it is shorter than one period of the on/off signal sent by the balancer T1. That is, the inductance value of the balancer T8 is set so that the operating waveforms when two lamps are lit and when one lamp is lit are as shown in FIGS. 2(a) and 2(b), respectively.

In this way, as is clear from FIGS. 2(a) and 2(b), the operating frequency can be made the same when two lamps are lit and when one lamp is lit, and as described in the conventional example, It becomes possible to easily take measures against problems such as noise and optical remote control interference. Furthermore, as can be seen from Figure 2(b), when one lamp is lit, the inductance of the balancer T is connected in series with the capacitor C2, which lengthens the circuit's oscillation period; During the period when the voltage is applied to the transistor 7r1 by the circuit 4, the gate circuit 2 prohibits conduction control of the transistor Tr+ by the separately excitation signal (output from the separately excitation signal generation circuit 1). There is no rush current.

In addition, in the waveform shown in FIG. 2(b), the separately excited signal “Hi”
gl+” level period and the V.E detection signal’s “’Higl+” level period.
+” level period partially overlaps, but this does not need to overlap, and in Figure 2 (a), 2
'High' level period of separately excited signal and VC when lighting the lamp
It does not matter if the period of the "High" level of the E detection signal partially overlaps, that is, the period during which the oscillating voltage is applied to both ends of the transistor Trl when two lamps are lit and when one lamp is lit. It is sufficient to select the inductance value of the balancer T so that both of them are shorter than one period of the separately excited signal.However, in reality, during the period when the drive signal of the transistor Tr+ is at the "High" level, the transistor It is desirable to shorten the period during which the oscillating voltage is applied to the transistor Tr+ to such an extent that the collector current of the transistor Tr flows.

K1 Takumi FIG. 3 is a circuit diagram of another embodiment of the present invention.

In this embodiment, three discharge lamps DL, -DL can be lit in parallel by using balancers T + and T 2 . The circuit configuration for on/off control of the transistor Tr is the same as that shown in FIG. 1. In this embodiment, when the discharge lamp DL is not lit, the discharge lamp DL2 is , the inductance component due to the winding n12 of balancer T1 is connected in series, and the lamp currents of discharge lamp DL2 and discharge lamp DL become unbalanced.
The winding n21.11□2 also has an inductance component. Therefore, if the inductance value of each winding is L, the discharge lamp DL2 has an inductance of 2L, and the discharge lamp D
The inductance of L is connected in series with L. Further, at i:j'er where the discharge lamp DL is not lit, the discharge lamp DL is connected to the discharge lamp DL, and an inductance of 2L is connected in series to the discharge lamp DL. When the discharge lamp DL2 is not lit, an inductance L is connected in series to each of the discharge lamps DL, DL, and DL.

In addition, if two of the three discharge lamps DL, -DL are not lit, only the discharge lamp DL2 is turned on (when it is lit, 2L are connected in series and discharged). When only the electric lamp DL or the discharge lamp DLs is lit, an inductance L is connected to each in series.

Even in the above combination, the transistor Tr
, balancer T + such that the oscillating voltage applied across it returns to zero within one period of the separately excited signal.

If you select the inductance value of T2, when one lamp is lit,
The dynamic frequency when two lamps are lit and when three lamps are lit can be made the same, and the same effect as in the first embodiment can be expected.

Figure 4 is a circuit diagram of yet another embodiment of the present invention. In this embodiment, when one lamp is lit, it becomes darker than when two lamps are lit. Therefore, control is performed to widen the on period of the transistor Tr+ so as to increase the light output when one lamp is lit.

In the separately excited signal generation circuit 1, tm, tm2 are general-purpose timer ICs (μPD15555 manufactured by NEC).As is well known, this timer IC has a trigger terminal (terminal 2) that is set to 1/3 V ec or less. Then, it is triggered and the output terminal (terminal No. 3) becomes the "Highll" level, and the discharge terminal (terminal No. 7) becomes high impedance. Also, when the threshold terminal (terminal 6) becomes 2/3 Vcc, the output terminal (terminal 3) becomes "Low" level,
The discharge terminal (terminal 7) also becomes "Low". Note that the No. 8 terminal is a power supply terminal, the No. 1 terminal is a ground terminal, the No. 4 terminal is a reset terminal, and the No. 5 terminal is a frequency control terminal.

A resistor R constituting the time constant circuit of the timer ICtml,
The control unit power supply voltage Vcc is applied to the series circuit of R< and the capacitor C5. The connection point between the resistor R5 and the resistor R1 is connected to the discharge terminal (terminal 7) of the timer ICte++. The connection point between the resistor R1 and the capacitor C6 is connected to the threshold terminal (terminal 6) and trigger terminal (terminal 2) of the timer ICt++++. Thereby, the timer ICtm+ constitutes an astable multivibrator that determines the oscillation period of the separately excited signal.

A control unit power supply voltage Vcc is applied to a series circuit of a resistor R1 and a capacitor C8 forming a time constant circuit of tie'/-I Ctm2. The connection point between resistor R6 and capacitor C5 is the threshold terminal (6
(Terminal No. 7) and the discharge terminal (Terminal No. 7).

The trigger terminal (terminal 2) of the timer ICtm is connected to the output terminal (terminal 3) of the timer ICtm+. Thereby, the timer ICtm2 constitutes a monostable multivibrator that determines the width of the separately excited off signal.

The output of the separately excited signal generation circuit 1 is N in the gate circuit 2.
It is connected to one input of an AND gate G via an OR gate G2. AND game) The other input of a + is the detection output of the element voltage detection circuit 4 connected to the inverter I.
, the logic is inverted and input. The output of the AND gate G is sent to the buffer B in the drive circuit 3.
It is also input to the base of the transistor Trl via a speed-up circuit consisting of a parallel circuit of a resistor R11 and a capacitor C.

As the element voltage detection circuit 4, a voltage dividing circuit including resistors R, , R2 is used. A Zener diode ZD for regulating the output of the element voltage detection circuit 4 is connected in parallel to the resistor R2. The detection output of the element voltage detection circuit 4 is connected to one input of the AND game G3. The other input of AND gate G3 is a NOR gate)
The output of G2 is connected. The output of the AND gate G3 is connected to the reset input R of the R,S flip-flop FF.

Control unit power supply voltage Vcc is applied to the series circuit of resistor R6 and capacitor C7. The terminal voltage of capacitor C7 is applied to the input of inverter 2. When the control unit power supply voltage Vcc is turned on, the capacitor C is turned on for a certain period of time.
1 is at a low level, the output of inverter I2 is at a high level, R1S flip-flop 1FF is set, and one input of NOR gate G2 is at a high level, so its output is at a low level. Become. After the certain period of time has elapsed, the terminal voltage of capacitor C7 becomes high, so the output of inverter I2 is maintained at a low level.
It will be done. Resistor R6 is connected to a capacitor when the power is turned off.
A diode D2 for discharging the charge of C, is connected in parallel.

The series circuit of resistor R8 and resistor R9 has a control unit power supply voltage V
cc is applied. The voltage at the connection point between the resistor R8 and the resistor R is input to the non-inverting input terminal of the operational amplifier ○P. The output voltage of the operational amplifier OP is fed back to the inverting input terminal of the operational amplifier OP. The output voltage of the operational amplifier OP is input to the No. 5 terminal of the timer ICtml. A resistor R1 is connected to the resistor R1 via a transistor Tr2.
10 are connected in parallel. The base of the transistor Trz is connected to the Q output of the RS flip-flop FF via a resistor R7.

The operation of this embodiment will be explained below. Figure 5 (a
) and (b) are operational waveform diagrams of this embodiment. Figure (a)
shows the operating waveform when two lamps are lit. Also, the same figure (b
) shows the operating waveform when the l lamp is turned on.

In both waveform diagrams, the waveform on the left side shows the operating waveform when the power is turned on, and the waveform on the right side shows the waveform during steady state with the time scale expanded.

First, when the power is turned on, the set force S of the RS flip-flop FF becomes "High" level for a moment, and its Q
The output is held at the "High" level. Therefore, the transistor Tr is turned on, and the non-inverting input voltage of the operational amplifier OP becomes, and this voltage remains as it is at 5 of the timer IC1st+.
No. terminal voltage. The operational amplifier OP is working here as an impedance converter.

The operating frequency of the timer IC is determined by the resistors R and R.

It is determined by the time constant of the capacitor Cg and the voltage at the No. 5 terminal, and the higher the No. 5 terminal voltage, the lower the operating frequency becomes. On the other hand, the timer ICtn2 is triggered when the voltage at the second terminal becomes 1/3 or less of the power supply voltage Vcc, and the output from the third terminal is at the "High!+" level for a certain period determined by the time constant of the resistor R6 and the capacitor C6. becomes.

When two lamps are lit, while the output of inverter 1 is at High level, the output of AND gate G is connected to NOR gate G.
The output of 2 can be obtained as is. This signal is supplied via the drive circuit 3 to the base of the transistor Tr+.

Next, when one lamp is lit, the period in which the oscillating voltage is applied to both ends of the transistor Tr becomes long, and the period in which the input voltage of the inverter is at the "High" level and the period in which the input voltage of the inverter Tr is
There is a partial overlap with the period in which the output of R gate G2 is at the "'Higl+" level, and during that period, the AND game)
The output of the RS flip 70-tube FF becomes the ")iigl+" level, and the reset input R of the RS flip 70-tube FF becomes the "High" level. As a result, the RS flip-flop FF
The Q output of , becomes u L o, IT level, and the transistor Tr2 is turned off. Therefore, op amp OP
The non-inverting input voltage and the voltage at the fifth terminal of the timer ICtm are Rs · V cc/ (Rs + n *), which are higher values than when two lamps are lit, and the operating frequency becomes lower. Accordingly, the output signal of NOR gate G2 becomes “
The period during which the lights are at the "Highb" level is longer than when two lamps are turned on.

As described above, in this embodiment, in order to increase the optical output when one lamp is lit, the separately excited signal is lower than when two lamps are lit.
Because the period of "Highb" level is made longer, the operating frequency is lower when one lamp is lit than when two lamps are lit. Therefore, the operating frequency when one lamp is lit and when two lamps are lit are completely the same. However, as described in the conventional example, since the operating frequency does not change so much as to be halved, the change in the lighting frequency is smaller compared to the conventional example.

(Effects of the Invention) As described above, the present invention provides a resonant single-stone switch that protects the semiconductor switch element by prohibiting conduction of the semiconductor switch element when an oscillating voltage is applied. In a separately excited inverter circuit, the inductance value of the second stabilizing element for connecting multiple discharge lamps in parallel is set so that the period during which the oscillating voltage is applied to the semiconductor switch element is shorter than one cycle of the separately excited signal. Since it is set to
The operating frequency does not change significantly depending on the number of discharge lamps lit, which has the effect of making it easy and inexpensive to take measures against noise and optical remote control interference.In addition, no inrush current flows through the semiconductor switch element, reducing loss. This has the effect of not causing an increase in the amount of water or damage to the device.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of one embodiment of the present invention, Fig. 2 is an operation waveform diagram of the same as above, Fig. 3 is a circuit diagram of another embodiment of the present invention, and Fig. 4 is a circuit diagram of an embodiment of the present invention.
The figure is a circuit diagram of still another embodiment of the present invention, FIG. 5 is an operation waveform diagram of the same as above, FIG. 6 is a circuit diagram of a conventional example, and FIGS.
The figure is the same operating waveform diagram as above, and Figure 9 is a circuit diagram of another conventional example.
FIGS. 10 and 11 are operation waveform diagrams of the same as above. 1 is a separately excited signal generation circuit, 2 is a gate circuit, 4 is an element voltage detection circuit, E is a DC power supply, T r + is a transistor,
DI is a diode, C5 is a capacitor, OT is an oscillation transformer, DLI and DI2 are discharge lamps, and T is a balancer.

Claims (2)

[Claims] (1) A DC power supply, a semiconductor switching element in the forward direction with respect to the DC power supply, a diode connected in parallel to the semiconductor switching element in the reverse direction with respect to the DC power supply, and an inductance element connected in series with the semiconductor switching element. , a resonant capacitor that exhibits a resonance state with the inductance element, a separately excited signal generation circuit that generates separately excited signals for repeatedly conducting conduction control of the semiconductor switch element, and a period during which an oscillating voltage exists across the semiconductor switch element. , a circuit that prohibits a separately excited signal from being input to the conduction control pole of the semiconductor switch element, and a plurality of parallel-connected circuits that apply an oscillating voltage generated by turning on and off the semiconductor switch element via a stabilizing element. the stabilizing element includes a first stabilizing element for limiting load current and a second stabilizing element for connecting a plurality of discharge lamps in parallel; is a stable element that has almost no inductance when a plurality of discharge lamps are lit, and has a predetermined inductance value when at least one lamp is not lit. A discharge lamp lighting device characterized in that the period of generation of an oscillating voltage at both ends of a semiconductor switch element is set to be shorter than one period of a separately excited signal even if at least one lamp goes out of lighting. (2) The inductance element is composed of an inductance seen from the primary side of a leakage type oscillation transformer, and the first stable element is composed of a leakage inductance of the oscillation transformer. Discharge lamp lighting device.