CN1046616C

CN1046616C - Preheat starting circuit for electronic ballast of fluorescent lamp

Info

Publication number: CN1046616C
Application number: CN96119871A
Authority: CN
Inventors: 应贤珠
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-10-08
Filing date: 1996-10-08
Publication date: 1999-11-17
Anticipated expiration: 2016-10-08
Also published as: CN1180290A

Abstract

The present invention relates to a circuit for electronic ballast with high-frequency output. An output circuit of the electronic ballast uses a secondary winding for preheating filaments, and the output circuit is connected with a coupling capacity; the output circuit is provided with a delayed triggering circuit to ensure a mode of firstly preheating and switching on a strip lamp; thus, the present invention solves the difficult problem of the matching of the electronic ballast and the ordinary strip lamp of a preheating type, and obtains the effects of reducing the blackening speed of the strip lamp and prolonging the service life of the strip lamp. Besides the reduction of working current, the present invention has the characteristics high-frequency starting, high-frequency working, no stroboflash, no noise, no electromagnetic interference, low requirement of starting voltage, obvious electricity saving, convenient combination and installation and wide application range, and a power factor is higher than 0.97.

Description

The preheat starting circuit that is used for electronic ballast for fluoresent lamp

The present invention relates to the circuit arrangement of discharge lamp igniting or control.

The present a kind of electric ballast operating circuit that uses; for example Xing Di company in Taiwan is in the EBT board SSB1 type electric ballast product of 94 years products; it adopts the filtering of AC power elder generation; protection; back rectification; filtering again; be high-frequency current through the inversion of semibridge system vibration translation circuit then, be defeated by fluorescent tube with output transformer, transient starting work; though sort circuit utilizes high-frequency work; exempt to use starter, noise is little, and electromagnetic interference is little; can accomplish not have stroboscopic; but the fluorescent tube melanism is still relatively more serious, and particularly it can't be used for common by ballast; filament; some fluorescent tubes of starter series circuit work, otherwise melanism is with even more serious.

The object of the present invention is to provide a kind of new preheat starting circuit, it can effectively reduce the melanism speed of lamp tube ends, prolongs the life-span of fluorescent tube, solves the suitable and corresponding problem with common fluorescent tube.

The present invention is on the basis of existing electric ballast operating circuit, change the circuit of its output,, be preheating to certain hour for its filament provides energy earlier with the output transformer of ballast, add operating voltage for again after the time-delay lamp tube ends filament, make its conducting work rapidly.Filament is identical through the condition of work of using at present with common fluorescent tube after the preheating, can be adaptive, and make fluorescent tube conducting work easilier under high-frequency work voltage, thereby can reduce operating current, reduce rush of current, the filament vaporization is slowed down, reach the purpose of prolonging lamp tube service life.

The preheat starting circuit that is used for electronic ballast for fluoresent lamp of the present invention, the elementary winding input higher-order of oscillation electric current of its output transformer, secondaryly be provided with three windings, one of them is with centre tapped winding, be access to an external filament contact of fluorescent tube one end behind the one end serial connection current limiting capacitance, centre cap is access to another filament contact, be used to provide filament pre-heating voltage, the other end is access to the bidirectional triode thyristor electrode of control circuit, another electrode output serial connection current limiting capacitance is received the contact of the fluorescent tube other end then, is used to produce lamp works voltage; Another winding is used to provide the delay trigger circuit operating voltage, be connected into series loop with rectifier diode, capacitance, constitute delay trigger circuit by RC charging circuit, field effect transistor, bidirectional triode thyristor, the intermediate contact of two divider resistances in parallel with said capacitance is in parallel with a charging capacitor, and cross-over connection is between the grid and source electrode of field effect transistor, the control utmost point of the drain electrode of field effect transistor and bidirectional triode thyristor joins, and also is provided with a resistance and constitutes active channel between the output of bidirectional triode thyristor electrode and rectifier diode; The 3rd winding is used to provide fluorescent tube other end filament pre-heating, also is serially connected with current limiting capacitance in the loop.

This circuit adopts high-frequency output transformer, uses high-frequency current work, and the preheating speed is adjustable, can make filament need reach preheat temperature.Use the electric ballast of sort circuit, can match with common fluorescent tube.After fluorescent lamp was opened, operating frequency reduced, but still about 25KHZ, the lamp works electric current is 190mA/36w, and is obviously lower than the situation of the common lamp works electric current 320mA/30w tubule (starting current 530mA/215v, power loss≤8) of present use.Because operating current reduces, electric current alleviates the impact of filament, and the filament durability improves, and will obviously be prolonged in the life-span of external fluorescent tube.

Be further described below in conjunction with specific embodiment and accompanying drawing thereof.

Fig. 1 is the circuit diagram of correlation technique.

Fig. 2 is a circuit diagram of the present invention.

Fig. 3 is to use the circuit diagram of the electric ballast of circuit of the present invention.

As shown in Figure 1, this circuit is the output circuit that once adopted the commercially available prod, because it belongs to the type of transient starting work, can not match with common fluorescent tube, otherwise startup work can be quickened the damage of filament on the contrary under the impact of high-frequency current.Output transformer T ₁Elementary winding L ₁The input high-frequency current, secondary winding L ₂, L ₃, be used to connect filament, produce high pressure and directly power to the both sides filament.Capacitor C plays coupling and metering function, has the compensation effect that reduces power consumption concurrently.This be must be many in the electric ballast way circuit a circuit.

Circuit of the present invention shown in Figure 2 has changed the basic structure of Fig. 1 circuit.Remove output transformer T ₁Input circuit identical outside, the secondary winding of output is as constituting preheating circuit and output services circuit.Capacitor C ₁, C ₃Playing metering function has concurrently and lowers the filament loss and raise the efficiency.Main winding L wherein ₂Operating current is provided, but must be by delay process, by delay trigger circuit control, then through capacitor C ₂Supply with filament, thereby improved the condition of work of filament.A, B, C, D are expressed as a set of connections contact of external filament.1-6 winding point can be set in an identical manner, use for many fluorescent tube parallel connections.Delay trigger circuit is by L ₃And VD ₁Direct-current working volts are provided.R ₁The formation path is used and the electrode 1 of triode ac switch VS joins.C ₅Provide operating voltage, R ₂, R ₃Be divider resistance and capacitor C ₄Constitute charging circuit, realize time-delay.Field effect transistor VT ₁Be used to amplify the control utmost point triggering work of triggering signal control VS.L ₂, VS, C ₂, C ₃, and fluorescent tube constitute the major loop of bidirectional triode thyristor work.VT ₁, R ₃, R ₂, R ₁Form control loop with the control utmost point, the electrode 1 of VS.

Its course of work is summarized as follows:

Behind the output transformer input high-frequency current, output current at first makes tube filament begin preheating, and charging circuit is to C ₄Charge, delay time, make the field effect transistor conducting after voltage raises, trigger the control utmost point of bidirectional triode thyristor, VS is conducting thereupon, and fluorescent tube conducting is again started working.

Fig. 3 has provided a circuit of electronic ballast embodiment who utilizes circuit of the present invention.T ₁Be isolating output transformer, its preheating with the output winding respectively parallel connection pick out and be access to filament, export four set of connections contacts and connect usefulness for connecting four tubes.Its left side is a power circuit, wherein V ₁Be overvoltage protection piezo-resistance, L, C ₁, C ₂Form anti-tampering input filter circuit, VD ₁-VD ₄Constitute bridge rectifier, C ₃Be electrolytic capacitor filter.The right is depicted as half raise formula switch transformed circuit, and the dc inversion after the rectification is become higher-order of oscillation electric current.Switch triode VT wherein ₂, VT ₃Alternate conduction work is by L ₇, L ₈The input positive feedback signal is set up vibration, output transformer T ₁On elementary winding L ₁Make oscillator coil and constitute high frequency oscillation circuit.C ₃, C ₄Main as dividing potential drop, VD ₆, VD ₇Be protecting diode, VD ₉, VD ₁₀Be negative peak protecting diode, C ₁₃Form alternating current path, R ₄, R ₅Current limliting usefulness, R ₆Setover R ₇, C ₁₂, ST forms circuits for triggering.The pre-thermal output winding of output transformer is identical with the described circuit of Fig. 2 with delay trigger circuit.The general technology index of electric ballast, this circuit all can meet or exceed, and power factor is higher than 0.97, total harmonic component is lower than 20%, crest factor is lower than 1.5, compares with the Inductive ballast of spreading and can economize on electricity 40%, and operating voltage is lower than at 25% o'clock and still can normally starts.This circuit can with present common fluorescent tube adapted.

Claims

1, a kind of preheat starting circuit that is used for electronic ballast for fluoresent lamp, its an output transformer (T ₁) elementary winding (L ₁) input higher-order of oscillation electric current, secondaryly being provided with three windings, one of them is with centre tapped winding (L ₂), one end serial connection current limiting capacitance (C ₂, C ₃) after be access to the external filament contact (A) of fluorescent tube one end, centre cap is access to another filament contact (B), be used to provide filament pre-heating voltage, the other end is access to the bidirectional triode thyristor electrode (2) of control circuit, then another electrode (1) output serial connection current limiting capacitance (C ₂, C ₃) receive the contact (C) of the fluorescent tube other end, be used to produce lamp works voltage; Another winding (L ₃) be used to provide the delay trigger circuit operating voltage, with rectifier diode (VD ₁), capacitance (C ₅) be connected into series loop, by RC charging circuit, field effect transistor (VT ₁), bidirectional triode thyristor (VS) constitutes delay trigger circuit, with said capacitance (C ₅) intermediate contact and a charging capacitor (C of in parallel two divider resistances ₄) parallel connection, and cross-over connection is in field effect transistor (VT ₁) grid and source electrode between, the control utmost point of the drain electrode of field effect transistor and bidirectional triode thyristor (VS) joins, and also is provided with a resistance (R between the output of bidirectional triode thyristor electrode (1) and rectifier diode ₁) the formation active channel; The 3rd winding (L ₄) be used to provide fluorescent tube other end filament pre-heating, also be serially connected with current limiting capacitance (C in the loop ₃).