KR880000509B1 - Operating device of discharge lamps - Google Patents

Abstract

This invention relates to a lighting device of a discharge lamp like a fluorescent lamp. The device has a stabilizer which is oscillated by RC time constant unlike being oscillated by the feedback of resonant current. This lighting device is composed of a power transistor Q1 for switching and transistor Q2 for small signal. A common AC potential is rectified by a full-wave rectifier which is constructed with bridge diode D1 and capacitor C1 in a small size, and pulsating DC potential is obtained. The pulsating DC potential is applied to the main current path through a transformer T1 and a transistor Q1.

Description

Electronic discharge lamp lighting device with constant output characteristics

1 is a known inverter type fluorescent lamp lighting device,

2 is an overall configuration diagram of the present invention,

3 is an explanatory diagram for determining the turn-on section,

4 is a waveform diagram of each part, (i) is a full wave rectification waveform diagram, (ii) is a collector waveform diagram of transistor Q1, and (iii) is a base waveform diagram of transistor Q1.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device such as a fluorescent lamp, and various lighting devices for turning on a discharge lamp have been devised in the past, but have various drawbacks for practical use. For example, general iron core choke ballasts have disadvantages such as uneven lighting start due to fluctuations in the power supply voltage, high power loss in itself, and heavy weight due to the use of iron core cores. The method of controlling the current as a resistor after multiplying the voltage by direct current to obtain a high voltage and performing an initial lighting is cheap, but the resistance of the lamp is significantly reduced by using a resistor element. It has a disadvantage. In addition, electronic ballasts using high frequency inverters developed in the 1980s have had significant effects in terms of sexual power, but in terms of price, they are much more expensive than conventional choke type ballasts. . In other words, Korean Patent Publication No. 84-854, "Fluorescent Lamp Lighting Device," uses a push-pull inverter and uses a main transformer that operates in the saturation region. Its disadvantage is that its efficiency is low and its power loss is increased and it cannot be realized at a low price. Therefore, in the present invention, in order to maximize the advantages of the electronic ballast, the main transformer is operated in a non-saturation region to minimize its power loss and to be configured at a simple and low price. Unlike oscillation of oscillation by feedback of resonant current, a new and simple type ballast is designed to maintain oscillation by RC time constant.

The circuit configuration of the present invention is shown in FIG. 2.

As shown in FIG. 1, a conventional electronic ballast using a current source inverter is composed of a push-pull method, and therefore, at least two high-power switching power transistors must be used. As shown in Fig. 1), it is composed of one switching power transistor Q1 and a low cost small signal transistor Q2. The basic operation is as follows. The commercial AC power is rectified by an onion rectifier circuit consisting of bridge diode D1 and a small capacity filter capacitor C1 to obtain a pulsating DC portential, which is then connected to the main current path consisting of the main transformer T1 and the transistor Q1. Will be authorized.

The initial operation of the main switching transistor Q1 is performed by a bias circuit consisting of R1 and R2. When current flows in Q1, the electromotive force of the feed back winding N3 of the transformer T1 is applied to Q1 through the capacitor C3 and the resistor R3. Applied Q1 is fully turned on. Turns on when transistor Q1 turns on. The electrical energy is stored as magnetic energy in the transformer T1 during the on period. When the amount of stored energy is Em, Em is

Where L denotes the sum of inductance values of windings N1 and N2 of transformer T1, Vdc is the instantaneous value of the pulse current supply, and ton represents the turn-on period of transistor Q1. . The ton, which is the period where transistor Q1 is turned on, is determined by the resistor R4, the time constant of capacitor C4 and the zener voltage of zener diode ZD1.The voltage charged in capacitor C4 is the zener voltage of zener diode ZD1 and the small signal transistor Q2. If it is greater than the base-emitter voltage of VBE2, Q2 is turned on and thus Q1 is turned off. At this moment, the magnetic energy stored in T1 is transferred to the lamp load by the voltage induced in the winding N2. At this time, if the current of the lamp load is IL, IL is

Can be expressed as:

Here, Ic represents the final value of the collector current of Q1. When the magnetic energy Em stored in T1 is completely transferred to the lamp load, Q1 is turned on again, repeating the same operation as the first time and continuing oscillation. Features of the present invention operating on the principle above can be summarized as follows.

First, since the present invention operates in a direct current pulse power supply, current flows in almost all sections of one cycle, thereby realizing a high power factor characteristic having a power factor of 0.9 or more on the input power supply side.

Second, the switching transistor Q1 turns independently before the main transformer T1 enters the saturation region. By turning it off, losses in T1 can be minimized.

Third, since the current of the lamp load becomes the demagnetizing current of the main transformer T1, it operates like a current source inverter.

Fourth, since the ton, which is the turn-on period of the main transistor Q1, depends on the voltage induced in the winding N3 of the main transformer T1, the output power delivered to the lamp load varies according to the ripple and fluctuation of the supply voltage. Very little nearly constant power is characterized. Since the fourth constant output characteristic is the most important feature of the present invention, it will be described in more detail as follows.

If the instantaneous value of the direct current pulse voltage is set to Vdc, the voltage VN3 induced in N3 during the turn-on period of Q1 ignores the voltage drop in the filament of the load lamp.

Can be expressed as:

And as in (Fig. 3), the voltage Vc4 of C4 is charged exponentially and if the initial value is set to 0,

It shows the same characteristics as

Therefore, when Vc4 becomes greater than the sum of the zener voltage Vz of ZD1 and the base-emitter voltage VBE2 of Q2, Q2 turns. Q1 turns on. Since it is turned off, ton, which is a section where Q1 turns on

Can be expressed as:

here,

to be.

Can be expressed as:

Therefore, when the instantaneous voltage Vdc of the DC pulse voltage increases, ton, which is the time period when Q1 turns on, decreases, and ton increases by decreasing Vdc, resulting in the variables R4, C4, VZ, By properly adjusting the values of N1, N2 and N3, the effect of Vdc change on Em can be minimized. In other words, in the conventional inverter type electronic ballast, the output of the circuit can be regulated even when the output voltage fluctuates from the fluctuation of the input voltage. have.

In the effect of the present invention, the test results compared with the existing electronic ballast for 30Watt first class are as follows.

1. Rated Input Characteristics Report

2. Output power characteristic report against voltage fluctuation

As described above, the present invention, unlike the electronic ballast employing the current-type or voltage-type circuit, uses a single switching power transistor to operate in a direct current pulsation power source to increase the power factor at the input power side and consume the power at the ballast itself. It is possible to reduce the power as much as possible, and it is a new design to realize the constant output characteristics of the lamp load according to the variation of the input voltage at a low price.

Claims (1)

As illustrated in the drawings and described above in the main text, the first connection N1 of the first transformer T1, the second winding N2 of the first transformer, and the series connection structure of the first transistor Q1 are connected to each other. Initial operation of the electronic ballast which connects the both ends (a, e) and turns on the lamp load with the high voltage induced in the second winding N2 of the first transformer T1 by the switching operation of the first transistor Q1. The oscillation operation is performed by a bias circuit to separate the DC pulse current power supply voltage, and the oscillation operation is then performed by the third capacitor C3 and the third resistor C3. This is done by applying to the base of the first transistor Q1 through), and the fourth resistor R4 and the fourth capacitor C4 connected in series with the third winding N3 of the first transformer T1. The number of zener voltages of the first zener diode ZD1 and the second transistor Q2 are set properly. , By varying the turn-on interval of the first transistor (Q1) in accordance with the instantaneous value of the direct-current power by controlling the pulsating flow off a discharge lamp lighting apparatus, characterized in that is configured so as to obtain a stable output power.

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