JPH088158B2 - Discharge lamp lighting device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device, and more particularly, to an electronic ballast type device for lighting a discharge lamp at a high frequency using an inverter, which has a power factor and efficiency. The present invention relates to a lighting device for a discharge lamp capable of improving the above.

(Prior Art) FIG. 2 is an electrical connection diagram showing an example of a conventional lighting device for a discharge lamp of this type. In the figure, 1 is an AC power source, 2
Is a rectifier circuit for full-wave rectifying this AC power supply. 3 is a capacitor, 4 is a choke coil, and these are rectifier circuits 2
It forms a smoothing circuit that smoothes the DC output from. A portion 5 surrounded by a broken line is an inverter which receives the DC signal Ei from the rectifier circuit and produces a high frequency signal for lighting the discharge lamp. In the inverter 5, 6 is an oscillation transformer using a magnetic leakage transformer, 7 and 8 are switching transistors, which turn on / off the DC signal Ei and apply it to the primary coils 9 and 10 of the oscillation transformer 6. 11 is the primary coil
Resonant capacitors connected in parallel to 9,10, 12 and 13 are bias resistors, and 14 is a feedback coil. The signal generated here is given to the bases of transistors 7 and 8, and transistors 7 and 8 are turned on / off alternately. Let Reference numeral 15 is a secondary coil of the oscillating transformer 6, 16 is a discharge lamp that discharges by a high-frequency voltage generated in the secondary coil 15, 17 and 18 are preheating coils, and filaments 19 and 20 of the discharge lamp 16 are generated by the voltage generated here. Is preheated. The current flowing through the discharge lamp 16 is determined by the voltage generated in the secondary coil 15 and the leakage reactance values of the primary coils 9 and 10.

(Problems to be Solved by the Invention) In the conventional device having such a structure, if a plurality of discharge lamps are to be lit, the discharge lamps are connected in series. It is not possible to do thinning-out lighting by thinning out only some of the
Further, in order to start the discharge, it is necessary to apply a certain voltage or more to each discharge lamp, which is a limitation.

Also, in order to improve the blackening of the tube end when the discharge lamp blinks, when a soft start is to be performed, it is necessary to add a circuit for soft start separately, which complicates the circuit configuration.

In addition, since current always flows through the filament of the discharge lamp, there is a problem that efficiency is reduced and the power factor is reduced due to the presence of the smoothing capacitor 3.

The present invention has been made in view of these problems, and an object thereof is to provide a discharge lamp capable of performing soft start with a simple configuration, performing thinning lighting, and improving power factor and efficiency. It is to provide a lighting device.

(Means for Solving Problems) According to the present invention which solves the problems described above, a first rectifier circuit for rectifying an AC voltage and an output terminal of the first rectifier circuit are connected via a diode. A smoothing capacitor; an inverter including an oscillating transformer that inputs a DC signal obtained from the first rectifier circuit and outputs a high frequency signal;
A discharge lamp to which a high frequency voltage obtained in the secondary coil of the oscillation transformer is applied between a pair of filaments, and a discharge current detection inserted and connected in series with the secondary coil of the oscillation transformer and the discharge lamp. Transformer, a second rectifier circuit for rectifying a high frequency output generated on the secondary side of the discharge current detecting transformer, and a relay means for interrupting the filament preheating current of the discharge lamp by the output of the second rectifier circuit. A feedback circuit for charging the output of the second rectifier circuit to a smoothing capacitor provided on the output side of the first rectifier circuit.

(Operation) When the discharge starts, the discharge current (tube current) flows through the discharge current detecting transformer, and the high frequency voltage is output to the secondary side. This high frequency output is rectified, actuating the relay and interrupting the filament preheating current. In addition, it is fed back so as to charge the smoothing capacitor. As a result, it has a soft start function and improves efficiency and power factor.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an electrical connection diagram showing an embodiment of the device of the present invention. In this figure, the same elements as those of each circuit element in FIG. 2 are designated by the same reference numerals. Here, the case where two discharge lamps are turned on is shown, but it is possible to increase the number of more discharge lamps by the same connection.

In the device of the present invention, the transformer 6 included in the inverter 5 does not use the magnetic leakage transformer as used in the conventional device shown in FIG. 2) using an oscillation transformer
A transformer for detecting the alternating frequency voltage generated in the secondary winding 15
The voltage is applied between the filaments 19 and 20 of the discharge tube 16 via 21. Here, 22 is a discharge current detection transformer 21.
Is a primary coil and 23 is a secondary coil.

Reference numeral 30 is a rectifier circuit for rectifying a high frequency signal generated in the secondary coil 23 of the discharge current detecting transformer 21, 24 is a relay operated by a current flowing through the rectifier circuit 30, and has normally closed relay contacts 26, 27. ing. These relay contacts 26 and 27 are
The preheating coils 17 and 18 are inserted and connected in a current supply path from the preheating coils 17 and 18 to the filaments 19 and 20 of the discharge lamp 16. Reference numeral 25 is a current control resistor, 29 is a diode for absorbing spikes of the relay 24, and 31 is a diode for preventing reverse current.

The output of the rectifier circuit 30 operates the relay 24 as described above and is fed back to one end of the smoothing capacitor 3 via the backflow prevention diode 31. In addition, 32 is a valley filling (STOP GAP) power supply diode connected in series with the smoothing capacitor 3.

In this device, the operating point of the discharge current detection relay 24 is determined by the primary coil 22, the secondary coil 23 of the discharge current detection transformer 21, the current control resistor 25, the smoothing capacitor 3 and the like. The discharge current detecting transformer 21 also serves as a ballast.

The operation of the apparatus thus configured will be described below.

When the AC power supply 1 is turned on, the inverter 5 turns the rectifier circuit 2
Oscillation is started by the output from. Immediately after the power is turned on, the smoothing capacitor 3 is not charged, so that the inverter 5 operates by the ripple component from the rectifier circuit 2 and the soft start becomes possible. When the inverter 5 starts oscillating, a high frequency voltage is generated in the secondary coil 15 of the oscillation transformer 6, and this is applied between the filaments 19 and 20 of the discharge lamp 16 via the primary coil 22 of the discharge current detecting transformer 21. Further, a current is supplied to the filaments 19 and 20 through the normally closed contacts 26 and 27 of the relay 24 to be preheated (the relay 24 is not operating when the power is turned on).

Here, when the voltage applied between the filaments 19 and 20 reaches the discharge start voltage of the discharge lamp 16, the discharge lamp 16 starts discharging, and the discharge current flows through the discharge current detecting transformer 21. This discharge current is rectified by the rectifier circuit 30, and the relay 24
And is fed back via the diode 31 so as to charge the smoothing capacitor 3. When the relay 24 operates, the normally closed contacts 26 and 27 are released, and the supply of the filament current to the filaments 19 and 20 is cut off. This reduces power consumption and improves efficiency. Moreover, the feedback to the smoothing capacitor 3 realizes the soft start function,
Helps improve power factor.

After that, the discharge of the discharge lamp 16 is continued in this state. The above operation is similarly performed in another discharge lamp unit (indicated by a portion 28 surrounded by a broken line) connected in parallel to the secondary coil 15 of the oscillation transformer 6. Further, the thinning lighting for each discharge lamp unit is performed by connecting / disconnecting between one terminal A of the secondary coil 15 of the oscillation transformer 6 and one terminal A of the discharge detection transformer 21. You can

In FIG. 1, the auxiliary coil 36, the diode 35 and the capacitor 33 provided in the oscillation transformer 6 apply a bias voltage to the transistors 7 and 8 via the bias resistors 12 and 13 so that the inverter 5 operates stably. It constitutes a circuit for giving and is not always necessary.

(Effects of the Invention) As described in detail above, according to the device of the present invention,
For a short time after the power is turned on until the smoothing capacitor is charged, the inverter operates with only the ripple component and discharge current flows.It has a soft start function and does not require a special soft start circuit. Will be easier. Further, since the magnetic leakage transformer is not used, it is possible to easily connect a plurality of discharge lamp units in parallel with one inverter and perform thinning lighting. Further, after the discharge is started, the filament current is cut off, or feedback is applied so as to charge the smoothing capacitor, so that the efficiency and the power factor can be improved.

[Brief description of drawings]

FIG. 1 is an electrical connection diagram showing an embodiment of the device of the present invention, and FIG. 2 is an electrical connection diagram of a conventional device. 1 ... AC power supply, 2,30 ... Rectifier circuit 3 ... Smoothing capacitor, 5 ... Inverter 6 ... Oscillation transformer, 15 ... Secondary coil 16 ... Discharge lamp 19, 20 ... Filament 21 ... Discharge Transformer for current detection 24 …… Relay, 26,27 …… Relay contact

Claims (1)

[Claims] 1. A first rectifier circuit for rectifying an AC voltage, a smoothing capacitor connected between output terminals of the first rectifier circuit via a diode, and a DC signal obtained from the first rectifier circuit. An inverter including an oscillation transformer that outputs a high frequency signal as an input, a discharge lamp to which a high frequency voltage obtained in a secondary coil of the oscillation transformer is applied between a pair of filaments, a secondary coil of the oscillation transformer, and a discharge lamp. A discharge current detecting transformer inserted and connected so as to be in series with the second current rectifying circuit, a second rectifying circuit for rectifying a high frequency output generated on the secondary side of the discharge current detecting transformer, and an output of the second rectifying circuit. Relay means for shutting off the filament preheating current of the discharge lamp, and a smoothing capacitor provided on the output side of the first rectifier circuit for outputting the output of the second rectifier circuit. The discharge lamp lighting apparatus having a feedback circuit for charging.