JPH0665179B2 - Discharge lamp lighting device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention relates to a pair of switching elements and a driving transformer by full-wave rectifying commercial alternating current and using this pulsating flow or DC power that smoothes this pulsating flow. The present invention relates to a device for driving an inverter made up of, for example, and lighting a discharge lamp with a high-frequency output of this inverter.

<Prior Art> A conventional device for lighting a discharge lamp of this kind at a high frequency is a full-wave rectifier for full-wave rectifying commercial alternating current of a commercial alternating-current power supply, and a direct-current power smoothed by a smoothing capacitor is supplied to an inverter. Each output of the pair of drive windings of the drive transformer in this inverter alternately turns on and off a pair of switching elements, causing a high-frequency current to flow in the discharge lamp, and the generation of this high-frequency current causes inductance at both ends of the discharge lamp. A high voltage is generated by series resonance of the element and the capacitance element, and the discharge lamp is configured to shift to a lighting state.

<Problems to be Solved by the Invention> In a conventional discharge lamp lighting device, a series resonance is caused at the same time when power is turned on and an oscillation operation is started, and the series resonance current causes a filament of the discharge lamp to rapidly rise. It is heated and a high voltage is generated at both ends of the discharge lamp, and it immediately shifts to a lighting state. Therefore, the discharge lamp will immediately shift to the lighting state when the filament has not been sufficiently preheated, and the filament is damaged or worn when the discharge lamp is lit, which is a factor that shortens the life of the discharge lamp. Has become.

Therefore, in order to eliminate such inconvenience, means for opening or short-circuiting a part of the circuit components of the series resonance circuit with an AC switch by a timer circuit from the time of power-on until a certain time has elapsed A lighting device has been devised which is configured to prevent the series resonance from occurring and preheat the filament of the discharge lamp with a high frequency current generated by the oscillating operation of the inverter. However, this device delays the generation of series resonance until a certain time elapses after the power is turned on, but since the combined impedance is large, the filament of the discharge lamp cannot be sufficiently preheated.

The present invention has been made in view of such a conventional problem, at the start of lighting the discharge lamp, the filament of the discharge lamp can be sufficiently preheated, and the lighting of the discharge lamp so as to eliminate the power loss after lighting. The purpose is to provide a device.

<Means for Solving the Problems> The present invention has the following technical means for achieving the above object. That is, the commercial AC is full-wave rectified by a full-wave rectifier, and this pulsating flow or DC power that smooths this pulsating flow is supplied to an inverter, and a high-frequency output of this inverter is used to light a discharge lamp. A pair of switching elements that are alternately on / off controlled by the outputs of a pair of drive windings of the drive transformer connected between the positive and negative output terminals of the rectifier, and a series connection in parallel with both switching elements. And a discharge lamp, an inductance element, and a pair of secondary windings connected in series between the intermediate connection point between the capacitors and the intermediate connection point between the switching elements. A filament heating transformer connected to both ends of the electric lamp, a capacitance element connected in parallel to the discharge lamp, and a filament heating transformer connected in parallel. An AC switches, characterized by comprising a timer circuit for outputting a gate signal to the gate terminal of the AC switch from power after a predetermined time has elapsed.

<Operation> When the power is turned on, the DC power that is full-wave rectified by the full-wave rectifier is supplied to the inverter, and the pair of switching elements are alternately switched by each output of the pair of drive windings of the drive transformer of this inverter. ON / OFF control. Here, when one of the switching elements is on, one switching element, one filament of a discharge lamp, a capacitance element, the other filament, an inductance element, and a primary of a filament heating transformer are connected from the positive output terminal of the full-wave rectifier. When a current flows through the winding and the other capacitor, and the other switching element is on, one capacitor from the positive-side output terminal of the full-wave rectifier, the primary winding of the filament heating transformer, the inductance element,
A current flows through the other filament of the discharge lamp, the capacitance element, the one filament and the other switching element.

From the moment the power is turned on until the timer time set in the timer circuit elapses, the primary winding of the filament heating transformer is connected to the series resonance circuit including the capacitance element including the discharge lamp and the inductance element. Is
And because it is designed for relatively high impedance, series resonance does not occur. When a current flows through the primary winding of the filament heating transformer, a voltage is induced in the pair of secondary windings of the transformer, and the output of each secondary winding is half-waved by the diode. It is rectified and supplied to both filaments of the discharge lamp, and the filaments are sufficiently preheated. Then, when the timer time set in the timer circuit elapses after the power is turned on, the AC switch is turned on by the gate signal output from the timer circuit, and the primary winding of the filament heating transformer is short-circuited. Therefore, the series resonance circuit causes LC series resonance, and a high voltage is generated between both filaments of the discharge lamp due to the series resonance current, and the series resonance circuit shifts to a lighting state. In this lighting state, the primary winding of the filament heating transformer is short-circuited by the AC switch, so that power loss due to this transformer does not occur.

<Examples> Hereinafter, preferred examples of the present invention will be described in detail with reference to the drawings.

In the figure showing one embodiment of the present invention, a commercial AC power supply 1
Full-wave rectification of the commercial alternating current by the full-wave rectifier 2, and this direct-current power is supplied to the separately excited inverter 3 including the oscillation circuit 4, the auxiliary switching element 5, the drive transformer 6, the pair of main switching elements 7, 8 and the like. It is supplied and the discharge lamp La is lit by the high frequency output of this inverter.

Two electrolytic capacitors 9 and 10 are connected in series between the positive and negative pole side output terminals of the full wave rectifier 2, and the intermediate tap of the primary winding 6A of the drive transformer 6 is connected to the intermediate connection point between them. 1
One end of the next winding 6A is connected to the negative side output terminal of the full-wave rectifier 2 via the auxiliary switching element 5 formed of a transistor and the resistor 11, and the other end is connected to the backflow prevention diode 12
Is connected to the negative side output terminal of the full-wave rectifier 2 via an ON / OFF control of the auxiliary switching 5, and a DC current is intermittently supplied from the intermediate tap of the primary winding 6A of the drive transformer 6. Therefore, a rectangular wave alternating voltage is generated in the primary winding 6A.

The oscillation circuit 4 for controlling ON / OFF of the auxiliary switching element 5 shows a semiconductor integrated circuit of the model name NE555 manufactured by Signetic Co., Ltd. as the oscillation element 13 which is a main constituent element in this embodiment. The oscillation frequency and the duty cycle can be arbitrarily changed by changing the time constant of. In this embodiment, a power supply terminal Vcc and a ground terminal GND are connected to both ends of a power supply electrolytic capacitor 10, and two timing resistors 14 for determining an oscillation frequency, which are connected in parallel to the electrolytic capacitor 10 and in series with each other, are provided. , 15 and the timing capacitor 16 are connected at the intermediate connection point between the timing resistors 14 and 15 with the discharge terminal DC, and at the intermediate connection point between the resistor 15 and the capacitor 16 with the threshold terminal TH and the trigger terminal TR, respectively. 16 is both timing resistors 14,15
Self-oscillation operation is performed by repeating charging and discharging via and output from the output terminal OUT. In addition, in order to perform self-oscillation operation, set the reset terminal RS to “0”.
It is necessary not to set the level, and in this embodiment, the reset terminal RS is connected to the charging positive electrode side of the power supply capacitor 10. Furthermore, a bypass capacitor 17 is connected to the control voltage terminal CV.
17 eliminates the influence of power supply noise. Furthermore, the oscillation output from the output terminal OUT is input to the base of the auxiliary switching element 5 via the base resistor 18, whereby the auxiliary switching element 5 is on / off controlled.

A pair of main switching elements 7 and 8 each composed of a transistor connected in series between the positive and negative pole side output terminals of the full-wave rectifier 2 are connected to the drive transformer 6 via base resistors 19 and 20 and resistors 21 and 22, respectively. Connected to the pair of secondary windings 6B and 6C, the main switching elements 7 and 8 are alternately turned on by the voltages alternately induced in the corresponding secondary windings 6B and 6C.
Controlled off.

A pair of electrolytic capacitors 23, 24 are connected in parallel to each of the main switching elements 7, 8 and in series with each other, and an intermediate connection point between the main switching elements 7, 8 and an intermediate connection between the capacitors 23, 24 are connected. Between the point and the inductance element 26, the discharge lamp La, the LC series resonance circuit consisting of the capacitance element 27 connected in parallel to this discharge lamp La and the primary winding 28A of the filament heating transformer 28 are connected. And a pair of secondary windings 28B of the filament heating transformer 28,
28C is connected to the filaments on both sides of the discharge lamp La via diodes 29 and 30, respectively. In addition, in the filament heating transformer 28, the primary winding is short-circuited and the discharge lamp La
A triac 31 for lighting up is connected in parallel, and the gate terminal of the triac 31 is further provided with a timer circuit 32 that outputs a gate signal after a lapse of a certain time from the power-on.
Is connected to the timer circuit 32, and a voltage is input to the timer circuit 32 from the auxiliary winding 6D wound around the driving transformer 6.

An AC unit 33 is connected between the commercial AC power supply 1 and the full-wave rectifier 2, and the secondary output of the current transformer 33 is full-wave rectified by a full-wave rectifier circuit 34. Are supplied to both ends of the electrolytic capacitor 10 for supplying power to the oscillation element 13.

Explaining other circuit elements, a protection element 35 such as a varistor connected to both ends of the AC power supply 1, a capacitor 36, a line filter 37, a capacitor 38, and a capacitor connected between the positive and negative pole side output terminals of the full-wave rectifier 2. The numeral 39 is for preventing the mixing of power source noise or the transmission of noise from the circuit to the power source 1 in addition to absorbing the external pulse. A resistor 40 and a Zener diode 41 are connected in series between the positive and negative output terminals of the full-wave rectifier 2, and the power supply voltage to the oscillator 13 is stabilized by the Zener voltage of the Zener diode 41. Further, discharge resistors 42 and 43 are connected in wave series to the electrolytic capacitors 23 and 24, respectively. Furthermore, diodes 44 and 45 are respectively connected in parallel to both main switching elements 7 and 8,
Each main switching element 7, 8 has a corresponding diode 44,
45 absorbs the pulsed electromagnetic energy of each secondary winding 6B, 6C of the drive transformer 6 and the inductance element 26.

Next, the operation of the above embodiment will be described. When the power is turned on, the commercial alternating current of the commercial power supply 1 is full-wave rectified by the full-wave rectifier 2, and this pulsating flow flows through the resistor 40 and the electrolytic capacitor 9 and is supplied to the power supply terminal V _CC of the oscillation element 13, The oscillating element 13 starts an oscillating operation and the auxiliary switching element 5 is on / off controlled, and at the same time, a small amount of electric charge is accumulated in the electrolytic capacitor 10. By the switching operation of the auxiliary switching element 5, the driving transformer 6
Since a DC current intermittently flows between the center tap and one end of the secondary winding 6A, an alternating voltage of a rectangular wave is generated in the primary winding 6A. Therefore, a voltage is alternately induced in the pair of secondary windings 6B and 6C of the driving transformer 6, and the pair of main switching elements are
7, 8 are alternately turned on and off via the drive circuit. At the same time, a voltage is also induced in the auxiliary winding 6D of the driving transformer 6, and the current resulting from this induced voltage is input to the timer circuit 32, and the timer circuit 32 starts the time counting operation. At this time, the triac 31 is off and the transformer for filament heating is
Since LC is connected and the impedance of the primary winding 28A is relatively high, LC series resonance does not occur.

Here, at the moment when one main switching element 7 is turned on, one main switching element 7 from the positive output terminal of the full-wave rectifier 2, one filament of the discharge lamp La,
Capacitance element 27, other filament of discharge lamp La, inductance element 26, filament heating transformer
A current flows through the primary winding 28A of 28 and the other capacitor 24 to the negative output terminal of the full-wave rectifier 2. Next, when the other main switching element 8 is turned on, one capacitor 23, the primary winding 28A of the filament heating transformer 28, the inductance element 26, the other filament of the discharge lamp La, and the capacitance element 27. , A current flows to the negative side output terminal of the full-wave rectifier 2 via one filament of the discharge lamp La and the other main switching element 8, and thus the driving of the inverter 3 generates a high frequency current.

When the high frequency current flows through the primary winding 28A of the filament heating transformer 28, a current according to the turn ratio thereof also starts flowing through the pair of secondary windings 28B, 28C, and these currents are respectively fed to the diode 29, Half-wave rectified by 30 and supplied to each filament of the discharge lamp La, each filament is forcibly and sufficiently preheated. On the other hand, when a high frequency current flows, an input current corresponding to this oscillation level flows to the primary side of the current transformer 33,
A current according to the winding ratio also starts to flow on the secondary side of the AC device 33. This current is full-wave rectified by the rectifier circuit 34 and applied to both ends of the electrolytic capacitor 10 for supplying power to the oscillating element 13, and power for permanently supplying energy to the load is accumulated. After the oscillation circuit 4 starts the oscillation operation,
Most of the power supply to the oscillator 13 is from the current transformer 33 via the rectifier circuit 34.

Then, when the timer time of the timer circuit 32 set to the time required for the discharge lamp La to be sufficiently overheated after the power is turned on, the gate signal is output from the timer circuit 32 and the triac 31 is turned on, The primary winding of the filament heating transformer 28 is short-circuited. Therefore, LC series resonance occurs due to the inductance element 26 and the capacitance element 27, a high voltage is generated across the discharge lamp La due to the series resonance current, and the discharge lamp La immediately shifts to the lighting state.
In this lighting state, the primary winding 28A of the filament heating transformer 28 is short-circuited, so that power loss due to this transformer 28 does not occur.

The present invention is not limited to the above description and illustrated examples, and various modifications may be included without departing from the scope of the claims. For example, the inverter 3 is shown as a separately excited type, but a self excited type can also be used. Further, although a triac is shown as the AC switch, a combination of a diode bridge and a transistor may be used.

<Effects of the Invention> As described in detail above, according to the discharge lamp lighting device of the present invention, the filament heating transformer having the pair of secondary windings in the LC series resonance circuit including the inductance element and the capacitance element is provided. The primary winding is inserted and connected, the output of each secondary winding is supplied to both filaments of the discharge lamp through the diode, respectively, and after a certain period of time has passed since the power was turned on, the AC switch is activated by the gate signal from the timer circuit. Since the primary winding of the filament heating transformer is short-circuited with the AC switch turned on, the filament heating transformer forcibly heats the filament of the discharge lamp sufficiently, and then the series resonance The discharge lamp can be lit by the generation of a high voltage due to, and the damage and wear of the filament when the discharge lamp is lit can be significantly reduced.
Further, since the primary winding of the filament heating transformer is short-circuited during lighting, it is possible to prevent power loss due to useless current flow.

[Brief description of drawings]

 The drawing is an electric circuit diagram of an embodiment of the present invention. 1 …… Commercial AC power supply 2 …… Full wave rectifier 3 …… Inverter 6 …… Drive transformer 6B, 6C …… Secondary winding (driving winding) 7,8 …… Switching element 23,24 …… Capacitor 26 …… Inductance element 27 …… Capacitance element 28 …… Filament heating transformer 28A …… Filament heating transformer primary winding 28B, 28C …… Filament heating transformer secondary winding 29,30… … Diode 31 …… Triac (AC switch) 32 …… Timer circuit

Continuation of the front page (56) Reference JP 61-271793 (JP, A) JP 59-130996 (JP, A) JP 63-4597 (JP, A) JP 59-149691 (JP , A) Actually opened 63-127098 (JP, U) Actually opened 58-110999 (JP, U) Actually opened 58-122398 (JP, U) Actually opened 58-118699 (JP, U) Actually opened 57-130996 (JP, U) Actual development Sho-58-150298 (JP, U)

Claims (1)

[Claims] 1. A device for full-wave rectifying commercial alternating current with a full-wave rectifier, supplying this pulsating flow or direct-current power smoothing this pulsating flow to an inverter, and lighting a discharge lamp with a high-frequency output of this inverter, A pair of switching elements that are alternately on / off controlled by the outputs of a pair of drive windings of a driving transformer connected between the positive and negative pole side output terminals of the full-wave rectifier, and a pair of switching elements connected in parallel to the switching elements. A pair of capacitors connected in series with each other, and a discharge lamp, an inductance element, and a pair of secondary windings connected in series between an intermediate connection point of the both capacitors and an intermediate connection point of the switching elements respectively form a diode. A filament heating transformer connected to both ends of the discharge lamp via a capacitance element connected in parallel to the discharge lamp, and a filament heating transformer connected in parallel to the filament heating transformer. An AC switch that is continued, the discharge lamp lighting apparatus, characterized by comprising a timer circuit for outputting a gate signal after a predetermined time has elapsed from when the power is turned to the gate terminal of the AC switch.