JPH0313717B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a discharge lamp lighting device using a transistor inverter device.

A fluorescent lamp lighting device using a transistor inverter device generally has a circuit configuration as shown in FIG. In the figure, 1 is a commercial AC power supply, 2
is a full-wave rectifier that performs full-wave rectification of the commercial AC power supply 1, and since a pulsating current that is not smoothed is obtained on its output side, it constitutes a non-smoothed DC power supply.
A transistor inverter device 4 is connected to the output side of the non-smoothed DC power supply 2 via an inductor 3. This transistor inverter device 4 includes a pair of transistors 5a, 5b and a primary winding 6.
a, an output transformer 6 consisting of a secondary winding 6b and a feedback winding 6c, a capacitor 7 and resistors 8a, 8
b, 8c.

A discharge lamp 9 such as a fluorescent lamp is connected to the secondary side of the output transformer 6.

Further, a switching element 11 such as a triax controlled by a conduction control circuit 10 is connected across a part of the secondary winding 6b of the output transformer 6. This switching element 11 is for short-circuiting a part of the secondary winding 6b of the output transformer 6 for a certain period of time, for example, about 1 second from the start of the discharge lamp 9, to reduce the high frequency output of the output transformer 6. . The reason for this configuration is that if the full power is applied before the electrodes of the discharge lamp are sufficiently heated, the electron emitting material will scatter significantly at the electrodes, causing the discharge lamp to darken early.

Since such a discharge lamp lighting device lights the discharge lamp with high frequency power, it is possible to light the discharge lamp with higher luminous efficiency than when lighting the discharge lamp with normal commercial frequency power. It is also possible to downsize the entire device. Further, by temporarily reducing the high frequency output, early blackening of the discharge lamp can be prevented.

However, the discharge lamp lighting device as described above has the following problems. In other words, since the commercial AC power supply voltage as shown in Figure 3a is full-wave rectified and the non-smoothed DC power supply voltage as shown in Figure 3b is applied to the transistor inverter, the output waveform of the transistor inverter is is in the state shown in FIG. 3c. When this high frequency voltage is applied to the discharge lamp, the discharge lamp is turned off when the high frequency voltage falls below the discharge sustaining voltage, and is turned on when the high frequency voltage rises again and reaches the discharge starting voltage. In other words, the lamp voltage and lamp current of the discharge lamp will be in the states shown in Figure 3 e and f, respectively.
A pause period t ₀ of the lamp current as shown in FIG. 3f results in a decrease in luminous efficiency. Note that FIG. 3d shows the voltage applied to the discharge lamp when a part of the secondary winding of the output transformer of the transistor inverter device is short-circuited.

Therefore, as shown in Figure 2, a commercial AC power supply 1
A smoothing DC power supply consisting of a full-wave rectifier 12, a smoothing capacitor 13, diodes 14a, 14b, etc. is separately provided, and this is configured to be applied to the transistor inverter device 4 together with the non-smoothed DC power supply. There is. In this way, the ripple in the output voltage supplied from the unsmoothed DC power supply is compensated for by the output voltage supplied from the smoothed DC power supply, so that the lamp current of the discharge lamp can also be adjusted as shown in Figure 3 f.
The rest period t ₀ as shown in Fig. 1 is eliminated, and the luminous efficiency is improved. Furthermore, since a large amount of energy is not required when the discharge lamp is re-ignited, power consumption can also be reduced.

However, with this configuration, a new problem arises in that even if an attempt is made to stop the switching element 11 that short-circuits a part of the secondary winding of the transistor inverter device by using ripples in the output voltage of the transistor inverter device 4, it is impossible to do so. This results in problems.

The present invention aims to provide a discharge lamp lighting device that solves the above-mentioned problems all at once.

FIGS. 4 and 5 show circuit diagrams of embodiments of the discharge lamp lighting device according to the present invention.

In FIG. 4, 1 is a commercial AC power source, 2 is an unsmoothed DC power source obtained by full-wave rectification of the commercial AC power source 1, and 3 is a smoothed DC power source obtained by rectifying and smoothing the commercial AC power source 1. be. A transistor inverter device 5 is connected to these two DC power sources via a common inductor 4. A discharge lamp 6 is connected to the output end of the transistor inverter device 5. Further, two of the output transformers (not shown) of the transistor inverter device 5
A switching element 7 such as a triax is connected across a part of the next winding. This switching element 7 is controlled to be conductive by a trigger circuit consisting of a resistor 8, a capacitor 11 and a voltage switch 12, which is controlled by a timer circuit consisting of a resistor 8, a diode 9 and an electrolytic capacitor 10. . That is, the discharge lamp 6 is made conductive for a certain period of time after starting, thereby shorting a part of the secondary winding of the output transformer of the transistor inverter device 5. A full-wave rectifier 13 is separately connected to the output side of the transistor inverter device 5, and a relay coil 15 is connected to the output end of the full-wave rectifier 13 via a transistor 14. the transistor 14
The base of is connected to the electrolytic capacitor 10 and diode 9 of the timer circuit via the zener diode 16.
connected between. In addition, the relay coil 1
A relay contact 17 driven by 5 is connected to open and close the smoothed DC power supply circuit.

Next, the operation of this circuit will be explained.

First, when the commercial AC power supply 1 is turned on, the power supply voltage is full-wave rectified by the full-wave rectifier 2 and applied to the transistor inverter device 5 . As a result, high-frequency power is output to the secondary side of the output transformer of the transistor inverter device 5, but the switching element 7 is kept in a conductive state by the trigger circuit for a certain period of time, for example, 1 second after the start of the engine. Since part of the secondary winding of the output transformer is shorted, the high frequency power is reduced and the discharge lamp 6 does not start.

In this state, the transistor 14 is off, the relay coil 15 is not energized, and the relay contact 17 maintains the smoothing DC power supply circuit in an open state. When the electrode of the discharge lamp 6 is sufficiently heated after a certain period of time has elapsed, charging of the electrolytic capacitor 10 of the timer circuit is completed and time-up occurs.
Current no longer flows in the trigger circuit of the switching element 7, and the switching element 7 is turned off due to natural commutation. In this case, since only the non-smoothed DC power supply is connected to the input of the transistor inverter device 5, the output also has a large amount of ripple, and the switching element 7 is surely turned off. As the timer circuit times up, a constant voltage is applied to the zener diode 16, so the transistor 14 is turned on, the relay coil 15 is energized, and the relay contact 17 closes the smoothed DC power supply circuit. Thereby, the transistor inverter device 5 operates by being supplied with input voltage from both the unsmoothed DC power source and the smoothed DC power source.

FIG. 5 shows an example in which a photocoupler is used in place of the mechanical relay device shown in FIG. Numeral 18 is a light emitting diode that emits light when the Zener diode 16 is turned on, and 19 is a diode that becomes conductive upon receiving the light from the light emitting diode 18.The operation of the entire circuit is the same as that in FIG. 4.

As is clear from the above description, the discharge lamp lighting device according to the present invention operates the transistor inverter device using only the non-smoothed DC power source for a certain period of time after starting the discharge lamp, and at the same time operates the transistor inverter device. A part of the secondary winding of the output transformer is short-circuited to prevent early blackening of the discharge lamp, and after the short-circuit of the secondary winding of the output transformer is reliably released, the non-smoothed DC power supply and smoothed The transistor inverter device is configured to operate on both DC power sources.

As a result, the discharge lamp can be lit with high luminous efficiency without causing early blackening, and the entire lighting device can be made smaller and lighter, which fully achieves the intended purpose. It is something that can be done.

[Brief explanation of the drawing]

1 and 2 are circuit diagrams of a conventional discharge lamp lighting device, FIG. 3 is a voltage waveform diagram of each part during operation of the device in FIG. 1, and FIGS. 4 and 5 are a discharge lamp according to the present invention. It is a circuit diagram of a lighting device. In FIG. 4 or 5, 1...Commercial AC power supply, 2...Unsmoothed DC power supply, 3...Smoothed DC power supply, 4...Inductor, 5...Transistor inverter device, 6...Discharge lamp , 7... Switching element, 15... Relay coil, 17... Relay contact, 18... Light emitting diode, 19... Light receiving diode.

Claims (1)

[Claims] 1 A commercial AC power source, an unsmoothed DC power source obtained by full-wave rectification of the commercial AC power source, and a smoothed DC power source obtained by rectifying and smoothing the commercial AC power source, and energized by these two DC power sources. a discharge lamp energized by the output of the transistor inverter, and a discharge lamp connected across a part of the secondary winding of the output transformer of the transistor inverter and discharged by a timer circuit. A switching element that short-circuits a part of the secondary winding for a certain period of time from the start of the lamp to reduce the output of the output transformer, and a relay device that operates in conjunction with the operation of the timer circuit that controls the switching element. The smoothed DC power source is separated from the transistor inverter device by the relay device while a part of the secondary winding of the output transformer of the transistor inverter device is short-circuited by the switching element. . A discharge lamp lighting device, characterized in that the smoothed DC power source is connected to a transistor inverter device by the relay device after a short circuit in a part of the secondary winding of the output transformer is released.