JPS5810398A - Device for firint 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] This invention relates to a discharge lamp lighting device.

A conventional discharge lamp lighting device has a choke coil L and a capacitor C at both ends of a commercial AC power supply V, as shown in Figure 1.
Connect the AC input terminal of the full-wave rectifier bridge D through the inverter IN, and connect the smoothing capacitor C2 to the pair of DC output terminals of the full-wave rectifier bridge D.
Connect the inverter IN as a load store and connect the fluorescent lamp LPi to the inverter I with the power source that has been full wave rectified and smoothed by the full wave rectifier bridge D and smoothing capacitor C2.
N is caused to oscillate at a high frequency, and the fluorescent lamp LP is lit with the output of this high frequency oscillation.

To explain in more detail, when the commercial AC power supply V is turned on,
The voltage that has been full-wave rectified by the full-wave rectifier bridge D and the smoothing capacitor C2 is applied to the chiller coil L.

The voltage is applied to the primary winding N of the oscillation transformer OT, through the entire N2, to the transistor Tr, and between the collector and emitter of the transistor Tr2. At the same time, the voltage stepped down by the power transformer PT passes through the base circuit B to the transistor Trx.
l Given to Tr2, transistor Tr.

Base current begins to flow through Tr2. Due to a slight imbalance in the circuit, a collector current begins to flow to either one of the transistors Tr□ and 'rr2. Now, if a collector current begins to flow in the transistor Tr□ on the primary winding N□ side of the oscillation transformer OT, a voltage is induced in the feedback winding N4 in the direction of increasing the base current of the transistor Tr, and the transistor Tr The collector current of the device increases and reaches saturation. However, when the collector current becomes saturated, the voltage induced in the feedback winding N4 disappears, the collector current begins to decrease, tends to become non-conductive, and eventually becomes non-conductive. On the other hand, the base current of the transistor Tr2 on the primary winding N2 side is changed because the voltage induced in the feedback winding N4 becomes forward biased from the time when the transistor Tr2 on the primary winding N□ side is saturated. begins to increase, and its collector current also increases. Furthermore, a voltage is induced in the feedback winding N4 in the direction of forward bias and eventually reaches saturation. Once saturation is reached, the collector current no longer increases,
Therefore, the voltage induced in the feedback winding N4 disappears,
The collector current begins to decrease and becomes non-conducting. These operations return to the initial state, and oscillation continues by repeating this process.

Due to this oscillation operation, a high high frequency voltage proportional to the primary/secondary turns ratio is generated in the secondary winding N3 of the oscillation transformer OT. This high frequency voltage turns on the fluorescent lamp LP using the leakage inductance of the oscillation transformer OT as ballast.

In addition, this discharge lamp lighting device connects a series circuit of a fluorescent lamp LP and an inductance L3, which is a dimming impedance, between the output terminals of an inverter IN, and connects a commercial AC power source V
A series circuit of a relay RY and a dimmer switch SW is connected between both ends of the inverter resistor and a capacitor C1, and the normally closed contact r3'1k of the relay RY is connected in parallel to the inductance L3. When the switch SW is opened, the normally closed contact RY1 is closed and the inductance is shorted, which causes the fluorescent lamp LP to be fully lit.When the dimmer switch SW is closed, the normally closed contact RY1K is opened. Turn on the fluorescent lamp LPi.

Note that C3 is a resonance capacitor. Base circuit B, aftermath rectifier bridge D2. Capacitor c4 and resistor R
, , R2. SB is a shield box and is grounded to the ground. The preheating circuit is illustrated and explained F!
A is omitted.

In such a conventional discharge lamp lighting device, when the fluorescent lamp LP is fully lit (normally closed), the oscillation transformer OT
The fluorescent lamp LP resonates with the resonance capacitor C3,
The oscillation frequency f as shown in FIG. 6(5). = 30KH
It exhibits a sine wave output waveform of z~50KH2. On the other hand, when the fluorescent lamp LP is dimmed and turned on (normally closed contact ry□: PA formation)
is the oscillation frequency feL-18 as shown in Fig. 6 (6)
KH2~40KH2 harmonic component (fdX n; n=3
-15), resulting in a distorted output waveform containing a large amount of Therefore, even though the output power is lower when the spotlight is on than when the spotlight is on, there are many harmonic components (especially the 3rd to 11th harmonics) on the oscillation frequency axis, and this component is generated outside the shield box SB. Lamp wiring LN1. There was a problem in that a large amount of radiation noise was generated using the LN2 and the fluorescent lamp LP as an antenna.

In order to solve the above problem, a discharge lamp lighting device as shown in FIG. 2 was proposed. This discharge lamp lighting device has a capacitor C5, which serves as a radiation noise prevention filter, connected between the output terminals of the inverter IN, that is, between the terminals of the secondary winding N30 of the (5) oscillation transformer OT. The configuration of is similar to that shown in FIG.

In this discharge lamp lighting device, since the capacitor C5 is connected to the oscillation transformer OT, both ends of the secondary winding N3 of the oscillation transformer OT are short-circuited with respect to harmonic components by the capacitor C5. It does not flow to LP, and the 6th
This results in an output waveform as shown in Figure (C), making it possible to reduce radiation noise during dimmed lighting.

However, since the capacitor C5 is connected across the secondary winding N3 of the oscillation transformer OT even during full lighting, there is a drawback that power loss due to capacitor C5 during full lighting is large. In addition, since the oscillation transformer OT is a single-cage type (the radiated noise prevention filter has a high short-circuit effect against harmonics during dimming, the oscillation frequency is different during full lighting and dimming, and the impedance of leakage inductance Abnormal oscillation (a phenomenon in which the output waveform resonates with the radiated noise prevention filter) may occur during full lighting or when no load (6) is applied. It is not possible to greatly enhance the filter effect during dimming, and its optimum value has a very narrow range.
It is also extremely difficult to negotiate.

Therefore, it is an object of the present invention to provide a discharge lamp lighting device that causes no power loss during full lighting and can reduce radiation noise during dimmed lighting.

An embodiment of this invention is shown in FIG. That is, in this discharge lamp lighting device, the C0M terminal of the switching contact ry2 of the relay RY is connected to the filter side output end of the secondary winding N3 of the oscillation transformer OT instead of the normally closed contact ry, and the NC terminal of the switching contact ry2 is connected to the filter side output terminal of the secondary winding N3 of the oscillation transformer OT. Connect the capacitor C5, which serves as a radiation noise prevention filter, to the connection point of the 3-pin fluorescent lamp LP on the inductance, and connect it to the lamp side output end of the secondary winding N3 of the oscillation transformer OT and the NO terminal of the switching contact r'12. The other parts are the same as those shown in FIG. 2.

In this discharge lamp lighting device, when the dimmer switch SW is opened and the switching contact ry2 is switched to the NC side, the inductance L3 is shorted and the fluorescent lamp LP is fully lit, and the capacitor C5 is connected to the oscillating transformer OT. Secondary winding N3
There is no power loss due to capacitor C5. On the other hand, close the dimmer switch SW and switch contact ry2.
When switched to the NO side, the fluorescent lamp LP is dimmed and lit by the inductance L3, and the capacitor C5 is connected to the secondary winding iN3 of the oscillation transformer OT, which is harmonically short-circuited to the fluorescent lamp LP. does not flow and radiated noise is reduced. When designing a filter for preventing radiated noise, it is only necessary to consider the dimmed lighting, and there is no need to consider abnormal oscillations, and a filter with higher filter effectiveness can be used. Furthermore, the normally closed contact ry of relay RY and the switching contact r
Since it is only necessary to change to f2 and change the connection of capacitor C5, it can be constructed easily and at low cost.

Another embodiment of this invention is shown in FIG. That is, this discharge lamp lighting device uses a parallel circuit of a capacitor C6 and an inductor 4 instead of the inductance L3 as a dimming impedance, and is otherwise similar to the device shown in FIG.

This discharge lamp lighting device operates in the same way as the one shown in FIG. 3 when the lamp is fully lit. On the other hand, during dimming lighting, capacitor C5 harmonically shorts both ends of secondary winding N3 of oscillation transformer OT to prevent harmonic noise from flowing into the fluorescent lamp LP, and also prevents harmonic noise from flowing into the fluorescent lamp LP. Due to the parallel resonance of a certain capacitor C and inductance 4, the frequency of f=-□ 7q is not outputted to the outside, and the dimming impedance can be used as a noise prevention filter.

In the above embodiment, the capacitor C5 is used as the radiation noise prevention filter, but a series circuit of the capacitor C and the inductance L5 may also be used.

As described above, the discharge lamp lighting device of the present invention includes an inverter, a series circuit of a discharge lamp and a dimming impedance connected between the output terminals of the inverter, and a dimming impedance (9) of the inverter. a switching contact having its own common terminal connected to its output end and one switching terminal of its own connected to the midpoint of the discharge lamp and the dimming impedance, and the discharge lamp side output end of the inverter connected to the switching contact. Since it is equipped with a radiation noise prevention filter that is connected between the other switching terminal and harmonically shorts the output terminals of the inverter, there is no power loss during full lighting, and moreover, when dimmed lighting This has the effect of reducing radiated noise easily and inexpensively.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional discharge lamp lighting device, Fig. 2 is a circuit diagram of a proposed example, Fig. 3 is a circuit diagram of an embodiment of the present invention, and Fig. 4 is a circuit diagram of another embodiment of the invention. Main part circuit diagram, Figure 5 is a circuit diagram of another radiated noise prevention filter, Figure 6 (3) is an output waveform diagram of the circuit in Figure 1 when all lights are on, and Figure 6 (B) is the same adjustment diagram. FIG. 6(C) is an output waveform diagram of the circuit of FIG. 2 during dimming lighting. ■...Commercial AC power supply, IN...Inverter, LP...
・(]0) Fluorescent lamp, L3... Inductance (impedance for dimming), C5... Capacitor (filter for preventing radiation noise), SW... Dimmer switch, RY... Relay, ry2... ...Switching contact (11) 1 〉 457 TOMUKU U"-I+-η→0 group"

Claims (1)

[Claims] an inverter, a series circuit of a discharge lamp and a dimming impedance connected between output terminals of the inverter, and a common terminal connected to the output terminal of the dimming impedance side of the inverter; A switching contact having one switching terminal connected to the midpoint of the impedance for the inverter, and the discharge lamp side output terminal of the inverter and the other switching terminal of the switching contact, connecting the output terminals of the inverter. A discharge lamp lighting device equipped with a radiation noise prevention filter that causes harmonic short circuit.