CN101500364A - Discharge lamp driving apparatus and driving method - Google Patents

Abstract

The invention relates to a driving device of a discharge lamp, which comprises a transformer, a switch component, a control circuit and at least one resonance circuit. The resonance circuit comprises a resonance capacitor and a resonance inductor, wherein the resonance inductor comprises an exciting inductor of the transformer. The driving device of the discharge lamp has the advantages that the exciting inductor of the transformer is led into the resonance circuit, thereby reducing the exciting inductance and leakage inductance of the transformer, decreasing the size of the transformer and lowering the cost.

Description

Discharge lamp driven apparatus and driving method

Technical field

The present invention relates to the drive unit and the driving method of discharge lamp.

Background technology

Nowadays, discharge lamp is as cold-cathode fluorescence lamp (Cold Cathode Fluorescent Lamp, CCFL) and external-electrode fluorescent lamp (External Electrode Fluorescent Lamp, EEFL), be used for liquid crystal display (Liquid Crystal Display, back light LCD) in a large number.Discharge lamp needs drive unit that the AC drive voltage of high frequency and stable lamp current are provided.Generally speaking, discharge lamp driven apparatus comprises control circuit, switch block, and transformer and resonant circuit, wherein control circuit control switch parts make it produce AC signal.Resonant circuit is become with the resonance capacitance group by resonant inductance usually, and resonant circuit is also referred to as accumulator, can store electric energy under specific frequency.

Figure 1A, 1B, 1C are the circuit diagram of existing discharge lamp driven apparatus.Discharge lamp driven apparatus shown in Figure 1A comprises control circuit 10, switch block 20, transformer T ₁, resonant circuit and discharge lamp L, wherein the resonant inductance in the resonant circuit is transformer T ₁The leakage inductance L of secondary winding _Ks, resonant capacitance is a capacitor C, capacitor C both can be and had added electric capacity, also can be made of the distributed capacitance and the parasitic capacitance of discharge lamp.Resonant circuit shown in Figure 1B in the discharge lamp driven apparatus, its resonant inductance are transformer T ₁The leakage inductance L of elementary winding _Kp, resonant capacitance is for adding capacitor C _pResonant circuit shown in Fig. 1 C in the discharge lamp driven apparatus, its resonant inductance is by transformer T ₁The leakage inductance L of elementary winding _KpLeakage inductance L with secondary winding _KsCommon formation, resonant capacitance is a capacitor C, capacitor C both can be and had added electric capacity, also can be made of the distributed capacitance and the parasitic capacitance of discharge lamp.In existing these three kinds of discharge lamp Driving technique, for fear of the magnetizing inrush current phenomenon occurring, the magnetizing inductance of transformer all is provided with greatly usually, can be considered open circuit, so omit in the drawings.

Be example now, the design process of parameter in its resonant circuit is described with the prior art among Figure 1A.As shown in Figure 1A, network 11 is composed in parallel by resonant capacitance C and discharge lamp L, and network 12 is by resonant inductance L _KsBe composed in series with network 11.Fig. 2 is that discharge lamp driven apparatus shown in Figure 1A is at resonance frequency f _ResonanceUnder impedance diagram, wherein

Be the equiva lent impedance of network 11,

Be the equiva lent impedance of network 12, Be resonant inductance L _KsImpedance, θ is

Phase angle.Discharge lamp driven apparatus in normal operation, the equiva lent impedance that needs the common network of forming of discharge lamp and resonant circuit is at resonance frequency f _ResonanceUnder be pure resistive, promptly its phase angle be 0 the degree.For the discharge lamp driven apparatus shown in Figure 1A, the equiva lent impedance of network 12

At resonance frequency f _ResonanceUnder be pure resistive, its phase angle be 0 the degree, with

Vertically, as shown in Figure 2.As shown in Figure 2,

${\stackrel{\→}{Z}}_{\mathrm{in}}={\stackrel{\text{\→}}{Z}}_c+{\stackrel{\→}{Z}}_{\mathrm{Lks}}$

$\left|{\stackrel{\→}{Z}}_{\mathrm{Lks}}\right|=\left|{\stackrel{\→}{Z}}_c\right|\·\sin \mathrm{\θ}$

And

Be resonant inductance L _KsAt resonance frequency f _ResonanceUnder impedance, have ${\stackrel{\→}{Z}}_{\mathrm{Lks}}=j\·2\·\mathrm{\π}\·f_{\mathrm{resonance}}\·L_{\mathrm{ks}},$ So, $L_{\mathrm{ks}}=\frac{\left|{\stackrel{\→}{Z}}_c\right|\·\sin \mathrm{\θ}}{2\·\mathrm{\π}\·f_{\mathrm{resonance}}}$

By the load characteristic and the decision of resonance capacitance of discharge lamp, so for certain discharge lamp and certain resonance frequency, under certain resonant capacitance value, its resonant inductance value is also certain.For prior art, its resonant inductance is the leakage inductance of transformer, and the size of resonant inductance value defines the size of transformer leakage inductance, thereby defines the volume and the cost of transformer.

Summary of the invention

The object of the present invention is to provide a kind of discharge lamp driven apparatus, this discharge lamp driven apparatus can effectively limit and utilize the static exciter inductance, thereby defines the volume and the cost of transformer, finally reaches the volume of reduction discharge lamp system and the effect of cost.

In order to reach the foregoing invention purpose, the present invention is a kind of discharge lamp driven apparatus, comprises transformer, switch block, control circuit and at least one resonant circuit, and described resonant circuit comprises resonant capacitance and resonant inductance, wherein, described resonant inductance comprises the magnetizing inductance of described transformer.

As described according to a preferred embodiment of the invention discharge lamp driven apparatus, wherein, described resonant circuit is coupled between described transformer and the described discharge lamp, comprises described Secondary winding of transformer leakage inductance.

As described according to a preferred embodiment of the invention discharge lamp driven apparatus, wherein, described resonant circuit is coupled between described control circuit and the described transformer, comprises the elementary winding leakage inductance of described transformer.

As described according to a preferred embodiment of the invention discharge lamp driven apparatus, wherein, described resonant capacitance is the distributed capacitance and the parasitic capacitance of described discharge lamp or adds independent capacitance.

As described according to a preferred embodiment of the invention discharge lamp driven apparatus, wherein, described discharge lamp is single or multiple parallel discharge lamps.

As described according to a preferred embodiment of the invention discharge lamp driven apparatus, wherein, described resonant circuit further comprises the ballast electric capacity of connecting with described discharge lamp.

As described according to a preferred embodiment of the invention discharge lamp driven apparatus, wherein, described transformer comprises a plurality of elementary windings.

As described according to a preferred embodiment of the invention discharge lamp driven apparatus, wherein, described transformer comprises a plurality of secondary winding.

As described according to a preferred embodiment of the invention discharge lamp driven apparatus, wherein, described discharge lamp is external-electrode fluorescent lamp or cold-cathode fluorescence lamp.

The object of the present invention is to provide a kind of discharge lamp driving method, this discharge lamp driving method can effectively limit and utilize the static exciter inductance, thereby defines the volume and the cost of transformer, finally reaches the volume of reduction discharge lamp system and the effect of cost.

In order to reach the foregoing invention purpose, the present invention is a kind of discharge lamp driving method, may further comprise the steps: step S1, and control circuit control switch parts produce first AC signal; Step S2, transformer receives described first AC signal, and generation second AC signal is used to drive discharge lamp on secondary winding, wherein, described AC signal produces resonance by resonant circuit, and the resonant inductance of described resonant circuit comprises the magnetizing inductance of transformer.

As described according to a preferred embodiment of the invention discharge lamp driving method, wherein, the resonant capacitance of described resonant circuit is the distributed capacitance and the parasitic capacitance of described discharge lamp or adds independent capacitance.

As described according to a preferred embodiment of the invention discharge lamp driving method, wherein, in described step S2, resonant circuit carries out resonance to described second AC signal, and the resonant inductance of described resonant circuit also comprises described Secondary winding of transformer leakage inductance.

As described according to a preferred embodiment of the invention discharge lamp driving method, wherein, in described step S2, resonant circuit carries out resonance to described first-class signal, and the resonant inductance of described resonant circuit also comprises the elementary winding leakage inductance of described transformer.

As described according to a preferred embodiment of the invention discharge lamp driving method, wherein, described resonant circuit further comprises the ballast electric capacity of connecting with described discharge lamp.

As described according to a preferred embodiment of the invention discharge lamp driving method, wherein, described discharge lamp is external-electrode fluorescent lamp or cold-cathode fluorescence lamp.

The invention has the advantages that, the magnetizing inductance of transformer is introduced resonant circuit, reduced the magnetizing inductance and the leakage inductance of transformer, thereby reduced the volume of transformer greatly, reduced cost.

Description of drawings

Figure 1A is the circuit diagram of one of discharge lamp driven apparatus in the prior art;

Figure 1B is two a circuit diagram of discharge lamp driven apparatus in the prior art;

Fig. 1 C is three a circuit diagram of discharge lamp driven apparatus in the prior art;

Fig. 2 is that the discharge lamp driven apparatus shown in Figure 1A is at resonance frequency f _ResonanceUnder impedance diagram;

Fig. 3 is the circuit diagram according to the discharge lamp driven apparatus of first specific embodiment of the present invention;

Fig. 4 is that discharge lamp driven apparatus shown in Figure 3 is at resonance frequency f _ResonanceUnder impedance diagram;

Fig. 5 is the circuit diagram according to second specific embodiment of discharge lamp driven apparatus of the present invention;

Fig. 6 is the circuit diagram according to second specific embodiment of discharge lamp driven apparatus of the present invention;

Fig. 7 is the circuit diagram according to the 3rd specific embodiment of discharge lamp driven apparatus of the present invention;

Fig. 8 is the circuit diagram according to the 4th specific embodiment of discharge lamp driven apparatus of the present invention;

Fig. 9 be according to the present invention the discharge lamp driving method the flow chart of first specific embodiment;

Figure 10 be according to the present invention the discharge lamp driving method the flow chart of second specific embodiment;

Figure 11 is for utilizing Nu-pulse according to the present invention ^TMThe schematic diagram of one of discharge lamp driven apparatus of technology; And

Figure 12 is for utilizing Nu-pulse according to the present invention ^TMTwo schematic diagram of the discharge lamp driven apparatus of technology.

Embodiment

The magnetizing inductance of transformer is provided with greatly usually in the prior art, can be considered open circuit, cause volume of transformer bigger, for the magnetizing inductance that further effectively utilizes transformer reduces volume of transformer simultaneously, the invention provides a kind of discharge lamp driven apparatus, its principle is to reduce the static exciter inductance, utilizes the magnetizing inductance of transformer to constitute the resonant circuit of discharge lamp driven apparatus, thereby reaches the purpose that the magnetizing inductance that effectively utilizes transformer reduces volume of transformer simultaneously.

Explain according to four specific embodiments of the present invention in detail respectively to Fig. 8 below in conjunction with accompanying drawing Fig. 3.Drive unit first specific embodiment

Fig. 3 is the circuit diagram according to first specific embodiment of discharge lamp driven apparatus of the present invention, and it comprises control circuit 10, switch block 20, transformer T ₁, resonant circuit and discharge lamp L, wherein the resonant inductance of resonant circuit is by the magnetizing inductance L of transformer _mLeakage inductance L with the transformer secondary output winding _KsCommon formation, resonant capacitance is a capacitor C.Wherein, capacitor C both can be and had added electric capacity, also can be made of distributed capacitance and the parasitic capacitance of discharge lamp L.Switch block 20 comprises at least one switch, switches by switch to produce first AC signal.Control circuit 10 is electrically coupled to switch block 20, and the switch of control switch parts 20 switches.Transformer T ₁Have an elementary winding and a secondary winding, its elementary winding electric is coupled to switch block 20 receiving first AC signal, and produces second AC signal on the level winding secondarily.Resonant circuit is electrically coupled to transformer T ₁Secondary winding, receive second AC signal, and drive discharge lamp L.

As shown in Figure 3, network 31 is composed in parallel by resonant capacitance C and discharge lamp L, and network 32 is by transformer T ₁The leakage inductance L of secondary winding _KsBe composed in series with network 31, network 33 is by transformer T ₁Magnetizing inductance L _mCompose in parallel with network 32.Fig. 4 is that discharge lamp driven apparatus shown in Figure 3 is at resonance frequency f _ResonanceUnder impedance diagram, wherein

Be the equiva lent impedance of network 31,

Be the equiva lent impedance of network 32,

Be the equiva lent impedance of network 33,

Leakage inductance for the transformer secondary output winding _LksImpedance,

Magnetizing inductance L for transformer _mImpedance, θ is

Phase angle, α is Phase angle.Discharge lamp driven apparatus in normal operation, the equiva lent impedance of the common network of forming of discharge lamp and resonant circuit is at resonance frequency f _ResonanceUnder be pure resistive, promptly its phase angle be 0 the degree.For discharge lamp driven apparatus shown in Figure 3, the equiva lent impedance of network 33

At resonance frequency f _ResonanceUnder be pure resistive, its phase angle be 0 the degree, with

With

Vertically.

Fig. 4 is that discharge lamp driven apparatus shown in Figure 3 is at resonance frequency f _ResonanceUnder impedance diagram, as shown in Figure 4,

${\stackrel{\→}{Z}}_s={\stackrel{\text{\→}}{Z}}_c+{\stackrel{\→}{Z}}_{\mathrm{Lks}}$

$\frac{1}{{\stackrel{\→}{Z}}_{\mathrm{in}}}=\frac{1}{{\stackrel{\→}{Z}}_s}+\frac{1}{{\stackrel{\→}{Z}}_{\mathrm{Lm}}}$

$\left|{\stackrel{\→}{Z}}_{\mathrm{Lks}}\right|=\left|{\stackrel{\→}{Z}}_c\right|\·\sin \mathrm{\θ}-\left|{\stackrel{\→}{Z}}_c\right|\·\cos \mathrm{\θ}\·\tan \mathrm{\α}$

And

Be resonant inductance L _KsAt resonance frequency f _ResonanceUnder impedance,

${\stackrel{\→}{Z}}_{\mathrm{Lks}}=j\·2\·\mathrm{\π}\·f_{\mathrm{resonance}}\·L_{\mathrm{ks}}$

So,

$L_{\mathrm{ks}}=\frac{\left|{\stackrel{\→}{Z}}_c\right|\·\sin \mathrm{\θ}-\left|{\stackrel{\→}{Z}}_c\right|\·\cos \mathrm{\θ}\·\tan \mathrm{\α}}{2\·\mathrm{\π}\·f_{\mathrm{resonance}}}$

By the load characteristic of discharge lamp and the decision of resonance capacitance, α is by the decision of choosing of the magnetizing inductance of the leakage inductance of transformer secondary output winding and transformer.L under prior art and the first drive unit specific embodiment of the present invention shown in Figure 3 shown in contrast Figure 1A _KsSize as can be known, the present invention has reduced the leakage inductance of secondary winding.

This shows that in the discharge lamp Driving technique of prior art, it is very big that the magnetizing inductance of transformer all is designed to be, and can be considered open circuit, and the present invention introduces resonant circuit with the magnetizing inductance of transformer, reduced the magnetizing inductance of transformer greatly.Thereby the present invention reduced the volume of transformer greatly, reduced cost.Simultaneously, the board area of whole drive unit also will reduce, and cost reduces more.

Drive unit second specific embodiment

As shown in Figure 5, the present invention also can be used for driving a plurality of discharge lamp L that are connected in parallel ₁To L _n, Fig. 5 is the circuit diagram according to second specific embodiment of discharge lamp driven apparatus of the present invention.

As shown in Figure 6, ballast electric capacity is introduced into the driving of a plurality of discharge lamps in parallel, and with each discharge lamp series connection, to reach the purpose of balanced lamp current, Fig. 6 is the circuit diagram according to second specific embodiment of discharge lamp driven apparatus of the present invention respectively.

Drive unit the 3rd specific embodiment

Fig. 7 is the circuit diagram according to the 3rd specific embodiment of discharge lamp driven apparatus of the present invention, it comprises a plurality of transformers and a plurality of resonant circuit, as shown in Figure 7, a plurality of resonant circuits are conductively coupled to a plurality of Secondary winding of transformer respectively, each resonant circuit all comprises the leakage inductance of the magnetizing inductance and the transformer secondary output winding of corresponding transformer, and resonant capacitance.Wherein, resonant capacitance both can be and had added electric capacity, also can be made of the distributed capacitance and the parasitic capacitance of corresponding discharge lamp.

Drive unit the 4th specific embodiment

Fig. 8 is the circuit diagram according to the 4th specific embodiment of discharge lamp driven apparatus of the present invention, and this discharge lamp driven apparatus comprises control circuit 10, switch block 20, transformer T ₁, resonant circuit and discharge lamp L, wherein resonant circuit is positioned at switch block 20 and transformer T ₁Between, transformer T ₁Turn ratio be n.The resonant inductance of resonant circuit is by the magnetizing inductance of transformer

Leakage inductance L with the primary winding _KpCommon formation, resonant capacitance C _pFor adding electric capacity.Switch block 20 comprises at least one switch, switches by switch to produce AC signal.Control circuit 10 is electrically coupled to switch block 20, with the switch switching of control switch parts 20.Resonant circuit is electrically coupled with switch block 20 and transformer T ₁Elementary winding between.Transformer T ₁Have an elementary winding and a secondary winding, its elementary winding electric is coupled to resonant circuit, and its secondary winding drives discharge lamp L.

Switch block in above-described each specific embodiment of the present invention, its topology can be half-bridge, full-bridge, recommends, and also can be Nu-pulse ^TMTechnology (U.S. Patent number: US7191305).Figure 11 is for utilizing Nu-pulse according to the present invention ^TMThe schematic diagram of one of discharge lamp driven apparatus of technology; Figure 12 is for utilizing Nu-pulse according to the present invention ^TMTwo schematic diagram of the discharge lamp driven apparatus of technology, wherein, transformer as shown in figure 11 comprises two elementary windings; Transformer as shown in figure 12 comprises the secondary winding of two elementary windings and two parallel connections.

Resonance frequency f _ResonanceCan be set to less than the operating frequency of switch block to realize zero voltage switch (Zero Voltage Switching, ZVS), also can be set to greater than the operating frequency of switch block to realize Zero Current Switch (Zero Current Switching, ZCS), or the operating frequency that is set to equal switch block to realize low input current.

The driving lamp of giving out light according to the present invention can be used for driving cold-cathode fluorescence lamp (Cold CathodeFluorescent Lamp, CCFL), also can be used for driving external-electrode fluorescent lamp (External ElectrodeFluorescent Lamp, EEFL).

The magnetizing inductance of transformer is provided with greatly usually in the prior art, can be considered open circuit, cause volume of transformer bigger, for the magnetizing inductance that further effectively utilizes transformer reduces volume of transformer simultaneously, the invention provides a kind of discharge lamp driving method, its principle is to reduce the static exciter inductance, utilizes the resonant circuit of the magnetizing inductance formation of transformer, thereby reaches the purpose that the magnetizing inductance that effectively utilizes transformer reduces volume of transformer simultaneously.

Driving method first specific embodiment

Fig. 9 is the flow chart according to first specific embodiment of discharge lamp driving method of the present invention, comprises step 91,92 and 93.

In step 91, control circuit control switch parts switch generation first AC signal; In step 92, transformer T ₁Elementary winding receive first AC signal, and produce second AC signal on the level winding secondarily; In step 93, resonant circuit receives second AC signal, it is carried out resonance, and driving discharge lamp, wherein the resonant inductance of this resonant circuit comprises the static exciter inductance, resonant capacitance can be made up of the distributed capacitance and the parasitic capacitance of described discharge lamp, also can be and adds independent capacitance, and resonant inductance also can comprise the leakage inductance of described Secondary winding of transformer.

Driving method second specific embodiment

Figure 10 is the flow chart of second specific embodiment of discharge lamp driving method according to the present invention, comprises step 101,102 and 103.

In step 101, control circuit control switch parts switch generation first AC signal; In step 102, resonant circuit receives first AC signal, it is carried out resonance, wherein the resonant inductance of this resonant circuit comprises the static exciter inductance, resonant capacitance can be made up of the distributed capacitance and the parasitic capacitance of described discharge lamp, also can be and add independent capacitance, resonant inductance also can comprise the leakage inductance of described Secondary winding of transformer; In step 103, transformer T ₁Elementary winding receive first AC signal, produce second AC signal on the level winding secondarily, and drive discharge lamp.

Discharge lamp driving method according to the present invention can be used for driving single discharge lamp, also can be used for driving a plurality of discharge lamps.When driving a plurality of discharge lamp, discharge lamp can be connected in parallel, and the ballast electric capacity of also can connecting on each discharge lamp is with the electric current of equilibrium by each discharge lamp.This discharge lamp driving method both can be used for driving external-electrode fluorescent lamp, also can be used for driving cold-cathode fluorescence lamp.

More than; be for those skilled in the art understand the present invention, and to the detailed description that the present invention carried out, but can expect; in the scope that does not break away from claim of the present invention and contained, can also make other variation and modification, these variations and revising all in protection scope of the present invention.

Claims (16)

1. a discharge lamp driven apparatus comprises transformer, switch block, control circuit and at least one resonant circuit, and described resonant circuit comprises resonant capacitance and resonant inductance, it is characterized in that, described resonant inductance comprises the magnetizing inductance of described transformer.

2. discharge lamp driven apparatus as claimed in claim 1 is characterized in that, described resonant circuit is coupled between described transformer and the described discharge lamp, comprises described Secondary winding of transformer leakage inductance.

3. discharge lamp driven apparatus as claimed in claim 1 is characterized in that, described resonant circuit is coupled between described control circuit and the described transformer, comprises the elementary winding leakage inductance of described transformer.

4. discharge lamp driven apparatus as claimed in claim 1 is characterized in that, described resonant capacitance is the distributed capacitance and the parasitic capacitance of described discharge lamp or adds independent capacitance.

5. discharge lamp driven apparatus as claimed in claim 1 is characterized in that, described discharge lamp is single or multiple parallel discharge lamps.

6. discharge lamp driven apparatus as claimed in claim 5 is characterized in that, further comprises the ballast electric capacity of connecting with described discharge lamp.

7. discharge lamp driven apparatus as claimed in claim 1 is characterized in that, described transformer comprises a plurality of elementary windings.

8. discharge lamp driven apparatus as claimed in claim 1 is characterized in that described transformer comprises a plurality of secondary winding.

9. discharge lamp driven apparatus as claimed in claim 1 is characterized in that, described discharge lamp is external-electrode fluorescent lamp or cold-cathode fluorescence lamp.

10. discharge lamp driving method may further comprise the steps:

Step S1, control circuit control switch parts produce first AC signal;

Step S2, transformer receives described first AC signal, and generation second AC signal is used to drive discharge lamp on secondary winding, wherein, described AC signal is carried out resonance by resonant circuit, and the resonant inductance of described resonant circuit comprises the magnetizing inductance of transformer.

11. discharge lamp driving method as claimed in claim 10 is characterized in that, the resonant capacitance of described resonant circuit is the distributed capacitance and the parasitic capacitance of described discharge lamp or adds independent capacitance.

12. discharge lamp driving method as claimed in claim 10 is characterized in that, in described step S2, resonant circuit carries out resonance to described second AC signal, and the resonant inductance of described resonant circuit also comprises described Secondary winding of transformer leakage inductance.

13. discharge lamp driving method as claimed in claim 10 is characterized in that, in described step S2, resonant circuit carries out resonance to described first-class signal, and the resonant inductance of described resonant circuit also comprises the elementary winding leakage inductance of described transformer.

14. discharge lamp driving method as claimed in claim 10 is characterized in that, described discharge lamp is single or multiple parallel discharge lamps.

15. discharge lamp driving method as claimed in claim 14 is characterized in that, described resonant circuit further comprises the ballast electric capacity of connecting with described discharge lamp.

16. discharge lamp driving method as claimed in claim 10 is characterized in that, described discharge lamp is external-electrode fluorescent lamp or cold-cathode fluorescence lamp.

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