JPS58145096A - Device for firing discharge lamp - 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] The present invention relates to an electric lamp lighting device.

[Technical background of the invention]

The following is one of the conventional discharge lamp lighting devices. That is, one end of both filament electrodes m3 &#Jb of the discharge lamp 3 is connected to the AC power supply 1 via the ballast 2, and a bidirectional wire 2 is connected between the other ends of both filament electrodes 3m and 3b of the discharge lamp 3. A diode 5 is connected through the terminal thyristor 4, and the diode 5 is connected to the diode 5 through the terminal thyristor 4.
An electronic switch circuit 6 that performs a switching operation by applying a voltage with a polarity opposite to that of the electronic switch circuit 6 is connected in parallel. At the time of starting, a power supply voltage exceeding the breakover voltage of the thyristor 4 is applied across the thyristor 4 to make the thyristor 4 conductive. As a result, a preheating current flows through the diode 5 to both filament electrodes 3a and 3b of the discharge lamp 30 during the AC half cycle, and during the other half cycle, the electronic switch circuit 6 performs a switching operation to cause the discharge lamp 3 to have both filament electrodes 3m and 3b. A /'P pulse voltage is applied between 3b and 3b. By repeating this operation, the discharge lamp 3 eventually lights up, and as a result, the thyristor 4 maintains its non-conducting state in which the voltage applied across the thyristor 4 is less than its breakover voltage.

In this operation, the voltage waveform applied to the discharge lamp when the discharge lamp 3 is not lit is the dotted line waveform V in FIG. As shown in FIG. 2, the voltage waveform applied to one discharge lamp when the discharge lamp 30 is turned on becomes as shown by the solid line waveform VL in FIG.

The voltage waveform VL includes a discharge sustaining voltage v when the discharge lamp 3 is re-ignited.
A pulsed restriking voltage vr exceeding L occurs. Note that the maximum voltage value of the voltage waveform v0 is vm, and vm>Vr.

[Problems with background technology]

In such a conventional device, the breakover voltage vBo of the thyristor 4 must be set within a narrow range of vm>vBo>vr. Moreover, when the ambient temperature of the discharge lamp decreases, the mercury vapor pressure decreases, the restriking voltage V increases, and the maximum weight and pressure value Vm may decrease due to fluctuations in the power supply voltage. It becomes quite difficult to set the breakover voltage v10, making it difficult to select a thyristor, and if the selection is made incorrectly, there is a risk that the thyristor may become conductive even after the discharge lamp is lit.

[Purpose of the invention]

This invention has been devised to solve these problems, and provides a discharge lamp lighting device that allows easy selection of circuit elements and ensures that the cyrisk remains non-conductive after lighting the discharge lamp. It is.

[Summary of the invention]

This invention divides the voltage applied between both filament electrodes of a discharge lamp, integrates the divided voltage with a capacitor, and applies it to a terminal trigger element on both sides. The three-terminal thyristor is made conductive to preheat the discharge lamp and apply a pulse voltage to the discharge lamp.

[Embodiments of the invention]

As shown in FIG. 3, one ends of both filament electrodes 13h and 13b of a discharge lamp 13 are connected to an AC power supply 1 via a ballast 12. A bidirectional three-terminal thyristor 1 is connected between the other ends of both filament electrodes 13m and 13b of the discharge phantom 13.
Connect the diode 15 through the diode 1
5 is connected in parallel with an electronic switch circuit 16 which performs a switching operation by applying a voltage of opposite polarity to the diode 15. The electronic switch circuit 16 includes a resistor J7.
, a diode 18 of opposite polarity to the diode 15;
, a series time constant circuit including a resistor 19 and a charging/discharging capacitor 20, an NPN transistor 22 connected in parallel to this time constant circuit via a resistor 21 on the collector side, and a collector-emitter between the transistor 220 and the emitter. and the base of this transistor 23 and the diode 18 of the above-mentioned time constant circuit.
a constant voltage conduction diode 24 connected to the connection point between the transistor 220 and the resistor 19; a positive characteristic thermistor 25 connected between the pace emitter of the transistor 220;
A resistor 5-26 connected between the resistor 20 and the anti-transistor side terminal of the resistor 21, a resistor 27 connected between the base and emitter of the transistor 23, and a resistor 17 and a diode 18 of the time constant circuit. resistor 28 connected in parallel to the series circuit of
It also includes a small-capacity capacitor 29 connected in parallel to a series circuit of a resistor 19 and a capacitor 20.

Also, both filament electrodes 13a of the discharge lamp 13.

A resistive voltage divider circuit 32 formed by connecting resistors 30 and 31 in four rows is connected between the other ends of the resistor 13b. A capacitor 33 is connected in parallel to the resistor 31, and the connection point between the resistor 31 and the resistor 30 is connected to a bidirectional two-terminal trigger element 34.
It is connected to f-) of the thyristor 14 via.

Note that both filament electrodes 13m of the discharge lamp 13.

A noise prevention capacitor 35 is connected between the other ends of 13b.

In the embodiment of the present invention configured as described above, as shown in FIG. Assuming that a cycle is applied to the discharge lamp 13, the discharge lamp continues until the charging voltage of the capacitor 33, which is charged with the voltage obtained by dividing this voltage v0 by the resistors 30 and 31, reaches the breakover voltage of the trigger element 34. The voltage vL of No. 13 rises similarly to the power supply voltage v0. Thereafter, at time t1, when the charging voltage of the capacitor 33 reaches the breakover voltage of the trigger element 34, the trigger element 34 becomes conductive and the thyristor 14 becomes conductive.

As a result, a current S8 flows as a preheating current to both electrodes 13m and 13b of the discharge lamp 130 via the disthyristor 14 and the diode 15. At this time, since there is almost no voltage drop between the thyristor 14 and the diode 15, the voltage vL is approximately zero. In addition, the preheating current 18 is controlled by the ballast 12 to a voltage vr
, the phase is delayed by nearly 90 degrees with respect to . At time t2 when this preheating current 18 becomes less than the holding current of the thyristor 14, the thyristor 14 becomes non-conductive and the current 18 becomes zero. Therefore, at this point, the voltage vL is the power supply voltage V. Both electrodes IRh, 1.3b of the discharge lamp 13 have the same waveform as
In between, a positive voltage and voltage suddenly appear. This voltage is applied across the thyristor 14 via a resistor 21 and a transistor 22. Further, this voltage is divided by resistors 30 and 31 and applied to a capacitor 33, thereby charging the capacitor 33. And time t! At time t3, which is slightly delayed, the trigger element 34 becomes conductive and the thyristor 1
4 is conductive. At this time, the capacitor 20 is charged via the resistor 17, the diode 18, and the resistor 19, but since the amount of charge is small, the constant voltage conduction diode 24 is not conductive, and therefore the transistor 23 is not conductive. Furthermore, since the transistor 23 is non-conductive, current flows through the resistor 26 to the transistor 22, so that the resistor 21
and current 1. through transistor 22. flows. The current i at this time is small because the resistance value of the resistor 21 is large, and is equal to the power supply voltage V. There is also a slight phase difference between the two.

And current 1. When becomes less than the holding current of the thyristor 14, the thyristor 14 becomes non-conductive and the stain current l becomes O.

In this way, a half cycle in which the power supply voltage v0 becomes negative again begins. As the above operations are repeated, stains occur.1. When is negative, a preheating current flows, and when is positive, the capacitor 20 is charged. Note that the capacitor 20 is also charged via the resistors 28 and 19, but the charge at this time is the current 1. When is a negative half cycle, resistor 19,
Since it is discharged via the capacitor 211, it does not contribute to the accumulated charge due to repeated charging to the capacitor 20. Thus the current 1. The charging voltage of capacitor 20 increases every half cycle when is positive. Since capacitor 20 exhibits almost zero impedance to alternating current, no alternating voltage appears across capacitor 200. However, since the resistor 19 is connected in series, an alternating current voltage appears in the form of small pulsations across the series connection of the resistor 19 and capacitor 20.

That is, a pulsating alternating current component appears at the connection point between the diode 18 and the resistor 19, superimposed on the direct current voltage rising during the reversal cycle. At time t4 when the tip of this pulsating component exceeds the Zener voltage of the constant voltage diode 24, the transistor 2
3 turns on, which instantly cuts off the transistor 22. Therefore, the ballast 12, electrodes 13m, 13b
, the current 1. flowing through the resistor 21. decreases rapidly, a transient phenomenon with the ballast 12 generates a sipulse voltage,
The discharge lamp 13 is started by applying power between the electrodes 13m and 13b, which have already been sufficiently preheated. At this time, diode 1
The tip of the pulsating component at the connection point between 8 and resistor 19 coincides with the peak point of current +8 flowing through the ballast, and this current 18 and voltage V. Since the phase difference is small, the first pulse voltage generated is voltage V. Since the current is generated at the maximum point and the current is at the maximum point, the voltage becomes the maximum during the half cycle, and the starting lighting of the discharge lamp 13 is performed satisfactorily. When the discharge lamp 13 starts discharging, the voltage VL between the electrodes 13m and 13b settles to vL in FIG. 2. Further, a restriking voltage V is generated by the discharge of the discharge lamp 13, but this voltage Vr is a kind of pulse voltage, and is integrated and absorbed by the capacitor 33, so that it has an effect on the conduction of the trigger element -10=34. There's no chance of it happening. Therefore, the breakover voltage vB0 of the trigger element 34 is set so that it does not conduct with the voltage across the resistor 31 obtained by dividing the voltage vL after discharge by the resistors 3θ and 31 (Vm') VB 0
>VL', the trigger element 34 is not conductive after the discharge lamp 130 is turned on, and the thyristor 14 is maintained in a non-conductive state. Note that Vm' is the voltage across the resistor 3 when the voltage is 1 m, and L' is the voltage across the resistor 31 when the voltage is VL. Since the setting range of the breakover voltage of the trigger element 34 can be expanded in this way, the breakover voltage can be easily set even if the influence of the ambient temperature of the discharge lamp 13 and fluctuations in the power supply voltage are taken into account. Also discharge lamp 13
When lit, power to the electronic switch circuit 16 is stopped, so that the charged capacitor 200 is immediately discharged via the resistor 19.28.

Note that even if the discharge lamp 130 is not lit by the first pulse voltage, the small capacity capacitor 29 is connected in parallel to the series circuit of the resistor 19 and the capacitor 20.
The capacitor 29 generates small-amplitude pulsations during a half cycle to control the transistor 23 on and off, which in turn causes the transistor 22 to operate on and off to continuously generate a voltage of 90 kHz, causing the discharge lamp 13 to turn on and off. is started. In addition, if the discharge lamp 13 continues to remain unlit for a relatively long period of time, the resistance value of the transistor 22 decreases due to the heat generated by the transistor 22, which increases the resistance value of the transistor 220. p) limits the collector current of transistor 22, thereby protecting transistor 22 from thermal damage;

In addition, the electronic switch circuit 16 does not generate a pulse voltage immediately after the power is turned on, and generates a pulse voltage after the photoelectric charge to the capacitor 20 is cycled every positive half cycle. During this time, connect both filaments of the discharge lamp 13 to the poles 13a.

13b is sufficiently preheated, and the discharge lamp 13 is not forced to start, so there is no risk of severe wear and tear on both filament electrodes, and the life of the discharge lamp can be extended.

In the above embodiment, even without the capacitor 29, the discharge lamp can be started because multiple pulses are generated. Further, since the resistor 27 only adjusts the drive current flowing to the transistor 23, the electronic switch circuit operates even without it.

Furthermore, instead of cutting off the current and generating pulses after a certain period of time as in the above embodiment, the electronic switch circuit may generate the /4' pulse simultaneously with the operation of the discharge lamp lighting device.

〔Effect of the invention〕

As described above, according to the present invention, the voltage applied between both filament electrodes of a discharge lamp is divided by a voltage dividing circuit, the divided voltage is integrated by a capacitor, and the voltage is applied to the element. Since the thyristor is made conductive to flow a preheating current and operate the electronic switch circuit, the breakover voltage of the trigger element can be easily set, and the circuit elements can be easily selected.13-1 ' This is the non-induction of the thyristor after the Sf discharge lamp is turned on.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram showing a conventional example, Fig. 2 is a waveform diagram showing the voltage between both filament electrodes when a discharge lamp is lit, Fig. 3 is a circuit diagram showing an embodiment of the present invention, and Fig. 4 (- and (b) are waveform diagrams showing the voltage between both filament electrodes and circuit current of the discharge lamp at the time of starting in the same example. 11... AC power supply, 12... Ballast, 13... discharge lamp , 14... bidirectional 3-terminal thyristor, 15...
・Diode, 16...Electronic switch circuit, 32...
- Resistance voltage divider circuit, 33... Capacitor, 34... Bidirectional two-terminal trigger element. Applicant's agent Patent attorney Takehiko Suzue 14-

Claims (1)

[Claims] An alternating current power supply, a discharge lamp with one end of both filament electrodes connected to this power supply via a ballast, and a diode connected between the other ends of both filament electrodes of this discharge lamp via a bidirectional three-terminal thyristor. A parallel circuit with an electronic switch circuit that performs switching operation by applying a voltage of opposite polarity to this diode, a resistive voltage divider circuit connected between the other end of the discharge lamp, and this voltage divider. A discharge lamp lighting device comprising: a capacitor connected in parallel to a voltage dividing resistor of a circuit and between a dart terminal of the thyristor via a bidirectional two-terminal trigger element.