JPS63175390A - 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 1] The present invention relates to a discharge lamp lighting device for lighting two or more discharge lamps having different rated lamp currents and different rated preheating currents.

[Background Art 1] Fig. 2 shows a discharge lamp lighting device using a self-excited inverter circuit. This discharge lamp lighting device operates using a DC power source (including rectified voltage of an AC power source) E as a power source, and a self-excited inverter circuit 1 is connected in series to both ends of the DC power source E using transistors Q + *Q. t, a driving transformer T1 that alternately biases and drives the transistors Q, Q, and a starting circuit ST, and an inductance 11 connected to the output of the self-excited inverter circuit 1, a capacitor C2, and a discharge lamp. A resonant circuit A consisting of a load R is connected.

When the power switch SW is turned on, charges are multiplied by IF on the capacitor C5 via the resistor R5, and when the voltage across the capacitor C3 reaches the breakover voltage of the switch element Q made of, for example, a diac or SBS, the capacitor C1 , the base current flows to the transistor Q2 via the switch element Q1 and the base/emitter of the transistor Q2, and the transistor Q2 is turned on. In other words, the starting circuit ST starts with the transistor Q at the same time as the power switch SW is turned on.
By making the circuit 2 conductive, the self-excited inverter circuit 1 is activated. Transistor Q2 as mentioned above
When turned on, DC power supply E1 capacitor C5, resonant circuit A1 drive transformer T, primary winding n1, transistor Q
2 and current flows. When this current flows through the primary winding #i n of the drive transformer T1, a voltage that forward biases the transistor Q2 is induced in the secondary winding #i n s, so that the conductive state of the transistor Q2 is maintained. after that,
The above current increases to charge the capacitor C3, but as the capacitor CI is charged, this current gradually decreases, and when the current approaches zero, the feedback voltage of the drive transformer T1 causes a voltage to be applied to the secondary winding n2. transistor Q
A voltage is induced in the secondary winding n, which forward biases the transistor Q2, and a voltage is induced in the secondary winding n, which reverse biases the transistor Q2, which turns off the transistor Q2.
1 turns on. Then, the resonant circuit A1 drive transformer T,
A closed circuit of the primary winding of the transistor Q is formed, and the capacitor C5 starts discharging. This capacitor C
When the discharge current of No. 1 decreases and approaches zero, a voltage of opposite polarity to the induced voltage of the secondary winding nztns described above is generated in the secondary winding #X.
n 2 *n=l is induced, transistor Q1 is turned off and transistor Q2 is turned on. By repeating the charging and discharging of the capacitor C1 in this manner, both transistors Q, , Q are turned on and off alternately to allow current to flow through the resonant circuit A, and the voltage of the capacitor C2 is applied to the load R. When the automatic inverter circuit 1 starts oscillating, the operation of the starting circuit ST is stopped. In other words, due to the conduction of the transistor Q2 of the automatic inverter circuit 1, the diode D,
Since the electric charge charged in the capacitor C3 via the capacitor C3 is discharged, the voltage across the capacitor C1 does not reach the breakover voltage of the switch element Q, and the switch element Q is turned off.

FIG. 3 shows a specific circuit of the resonant circuit A. In this resonant circuit A, the load R is a series connection of discharge lamps αIt Ot2 having different rated lamp currents and 1 rated preheating currents. Discharge lamp a, 1. In α2, filament F+ to F for a certain period of time from the time the power is turned on.

A switch S that closes the preheating circuit 2 for a certain period of time after the power is turned on;
, F, a preheating transformer Tz through which a preheating current flows, and the other filament F of the discharge lamp q2.

and an auxiliary winding n4 that cancels the inductance of the inductance L, lowers the impedance of the resonant circuit A, and increases the resonant current during the preheating period when the switch SI is closed. It is.

Note that a transformer including an auxiliary winding n4 as a secondary winding is used as the inductance L1.

Hereinafter, the preheating operation of the discharge lamps Q, +-Q, and z will be explained. When the power is turned on, the switch Sl is closed and the preheating current (1) flows through the primary winding n21 of the preheating transformer T2, the primary winding n31 of the preheating transformer T, the auxiliary winding n1, and the inductance. This preheating current I is set to the rated preheating current of the discharge lamp α1. Now, preheating transformer T
If we calculate the preheating current 2 flowing on the secondary side of A current near IA flows as current I2,
If the resistance of the secondary winding n0 is R1°, then I22R. A copper loss occurs.

For this reason, it is necessary to increase the wire diameter of the secondary wires 8+12, which results in the problem that the shape of the preheating transformer T becomes large.

[Objective of the Invention 1 The present invention has been made in view of the above-mentioned problems, and its object is to reduce the current flowing through the secondary winding of the preheating transformer and to downsize the preheating transformer. An object of the present invention is to provide a discharge lamp lighting device that ends with.

[Disclosure of the Invention 1 (Structure) The present invention comprises an inverter circuit that converts a DC power source into a high frequency voltage by switching a switching element, a series circuit of a capacitor and an inductance connected in series to the output of the inverter circuit, and the above-mentioned A resonant circuit consisting of a plurality of discharge lamps with different rated preheating currents connected in series to both ends of a capacitor, and a preheating circuit that preheats the filament of the discharge lamp for a certain period of time from the time the power is turned on, are provided. A plurality of preheating transformers that preheat the filament are connected in series with the primary winding of the preheating transformer to cancel out the inductance of the above inductance, and the rated preheating current of the discharge lamp with the largest rated preheating current is applied to the primary winding of the preheating transformer. The preheating circuit is provided with an auxiliary 84s for passing a preheating current corresponding to the preheating current, and a second preheating transformer for passing the preheating current through the filament of the discharge lamp with the smallest preheating current, and preheating the filament of the discharge lamp with the smallest preheating current. The current flowing through the next winding is divided from the preheating current, and the current flowing through the filament of the discharge lamp with the smaller rated preheating current is set to the rated preheating current of that discharge lamp. The current flowing through the secondary 8#i of the preheating transformer that preheats the filament is made to be only the difference current between the preheating current corresponding to the largest rated preheating current and the smallest rated preheating current,
The current flowing through the secondary winding of the preheating transformer, which has the smallest rated preheating current, is suppressed to a small value, allowing the preheating transformer to be made smaller.

(Example) FIG. 1 shows a resonant circuit A according to an embodiment of the present invention.

The difference between the resonant circuit A of this embodiment and the conventional resonant circuit A shown in FIG. 3 is that the @ light beginning of the secondary winding #1n32 of the preheating transformer T3 is reversely wound, and the secondary winding The discharge lamp (Lx's filament F4, auxiliary winding n4, and preheating transformer T, secondary volume #iLn:12
It is connected to the bean.

The preheating current 1. is applied to the primary winding n of the preheating transformer T3. , a secondary current I flows in the direction shown in the figure due to the induced voltage in the secondary winding n3□ of the preheating transformer T. The preheating current 11 then flows through the preheating transformer T, the primary winding ns+, and the auxiliary winding n to the filament F of the discharge lamp 0.2. However, the secondary winding of preheating transformer T3 #! ns
The current I2 flowing through the filament F is divided by the current flowing through the filament F, and the current I2 flows through the filament F, and the current I2 flowing through the filament F is the current flowing through the secondary winding IF2. canceled out. Therefore, the preheating current I is the rated preheating current of the discharge lamp t1.

The rated preheating current of discharge lamp α2 is filament F.

Secondary winding of preheating transformer T, so as to flow to @ n 3□
All you have to do is set the current that flows. For this reason, in the present example, the current flowing through the secondary winding nst of the preheating transformer T was close to IA, but in this embodiment it is 100 to 200 soA.
The current value can be set to a relatively low value. Therefore, the loss of the secondary winding n32 of the preheating transformer T can be reduced (0) For example, the current flowing through the secondary winding n32 of the preheating transformer T3 is conventionally 800-A, but in this embodiment, the current flowing through the secondary winding n32 is 200-A.
Assuming 0*A, the copper loss can be reduced by a factor of 16.

Therefore, the wire diameter of the secondary winding n32 can be made thinner, and the preheating transformer T can be made smaller. Here, if the secondary current of the preheating transformer T is reduced from 800 * A to 200 A, the number of turns of the secondary winding n31 needs to be quadrupled according to equation (1) in the background art section. It can be said that increasing the number of turns is not a problem compared to reducing the wire diameter by reducing the copper loss at the secondary winding port 2.

[Effect of the Invention J As described above, the present invention comprises an inverter circuit that converts a DC power source into a high frequency voltage by switching a switching element, a series circuit of a capacitor and an inductance connected in series to the output of the inverter circuit, and It is equipped with a resonant circuit consisting of a plurality of discharge lamps having different window preheating currents connected in series to both ends of the capacitor, and a preheating circuit that preheats the filament of the discharge lamp for a certain period of time from when the power is turned on. A discharge lamp with the largest preheating current is connected in series with the primary winding of the preheating transformer to cancel the inductance of the inductance, and the primary winding of the preheating transformer is connected in series to preheat the filament of the electric lamp. The preheating circuit is provided with an auxiliary winding that passes a preheating current corresponding to a window preheating current of The current flowing through the secondary winding of the preheating transformer to be preheated is divided from the preheating current, and the current flowing through the filament of the discharge lamp with the smaller window preheating current is set to the window preheating current of that discharge lamp. Therefore, the current flowing in the secondary winding of the preheating transformer that preheats the filament of the discharge lamp with the smallest window preheating current is the preheating current corresponding to the largest window preheating current and the smallest of the window preheating currents. Only the difference current between the preheating transformer and the preheating transformer is required, and therefore, the current flowing through the secondary winding of the preheating transformer, which has the smallest window preheating current, can be suppressed to a small value, and this preheating transformer can be made smaller.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a resonant circuit according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing a conventional discharge lamp lighting device, and FIG. 3 is a circuit diagram showing the same resonant circuit. 1 is an inverter circuit, 2 is a preheating circuit, A is a resonant circuit, C2 is a discharge lamp, E is a DC power supply, Q,,Q. is Trannosta, I2. T, preheating transformer, Fl~F
, is the filament, ■ is the preheating current, I2 is the filament current, ■ is the secondary current, n12 is the secondary winding, 1 is the auxiliary winding, C2 is the capacitor, and Ll is the inductance. Agent Patent Attorney Ishi 1) Chief 7F, ~F. I1...Preheating current I2 Fig. 2 3N

Claims (1)

[Claims] (1) An inverter circuit that converts a DC power source into a high-frequency voltage by switching a switching element, a series circuit of a capacitor and an inductance connected in series to the output of this inverter circuit, and a series circuit connected in series to both ends of the capacitor. A plurality of preheating transformers that preheat the filaments of each of the discharge lamps, including a resonant circuit consisting of a plurality of discharge lamps having different rated preheating currents, and a preheating circuit that preheats the filaments of the discharge lamps for a certain period of time from when the power is turned on. and an auxiliary winding connected in series with the primary winding of the preheating transformer to cancel the inductance of the inductance and to flow a preheating current corresponding to the rated preheating current of the discharge lamp with the largest rated preheating current to the primary winding of the preheating transformer. The preheating circuit is provided with a wire, the preheating current is passed through the filament of the discharge lamp with the smallest preheating current, and the current is passed through the secondary winding of the preheating transformer that preheats the filament of the discharge lamp with the smallest preheating current. A discharge lamp lighting device characterized in that a preheating current is branched from the preheating current and the current flowing through the filament of the discharge lamp having a small rated preheating current is set to the rated preheating current of the discharge lamp.