CN1925711A - Driving circuit for discharge lamp and driving method thereof - Google Patents

Abstract

This invention relates to discharging lamp drive circuit to drive lamp with first capacitor property with direct voltage source, second capacitor, transducer and switch circuit, wherein, first end of second capacitor is coupled to direct voltage source with second end connected to earth through switch to determine whether or not to connect second end of second capacitor to earth; the both ends of transducer are coupled to first and second ends of second capacitors to couple two ends of first capacitor to make transducer two sides generate drive current signals to light lamp due to preset impulse signals.

Description

The drive circuit of discharge lamp and its driving method

Technical field

The invention relates to a kind of drive circuit of discharge lamp, and particularly relevant for a kind of drive circuit method of not using the discharge lamp of pulse signal driving.

Background technology

Be used to provide the discharge lamp of light source, fluorescent lamp for example, a large amount of is applied on two industries, industry and the consumption market, and the principle of this type of discharge lamp generally is the external power source of lamp body, via electrode electric energy is sent into the gas that participates in discharge, and it is luminous to produce photoelectric effect; The greatest problem of this kind discharge lamp is that electrode participates in photovoltaic reaction and consumes, and makes not beneficial prolongation of life-span.There is the another kind of electrode that adopts electric energy to be sent into the design that the gas that participates in discharge produces the luminous discharge lamp of photoelectric effect in the recent period, can significantly prolongs lamp body useful life by dielectric layer.But known dielectric layer discharge lamp mostly drives its luminous (for example United States Patent (USP) 6th, 568, No. 774) by pulsed current signal, and the discharge lamp that this kind pulsed current signal drives generally all has the relatively poor problem of energy conversion efficiency.

Fig. 1 illustrates a kind of drive circuit figure of known discharge lamp.Please refer to Fig. 1, the drive circuit of known discharge lamp has comprised primary side circuit 110 and secondary side circuit 120, this two couple each other via transformer 130.In primary side circuit 110, the two ends of current source Q, the two ends of coupling capacitance device Cp respectively.In addition, first end of the first end coupling capacitance device Cp of the primary side W1 of transformer 130, second end of the primary side W1 of transformer 130 then couples first source of nmos pass transistor NT/drain end.In addition, the gate terminal of nmos pass transistor NT couples time-pulse signal generator SE 112, and its second source/drain end is second end of coupling capacitance device Cp then.In addition, the secondary side circuit has comprised discharge lamp L, and it is coupled on the secondary side W2 of transformer 130.In general, discharge lamp L has discharge tube and some sparking electrodes of filling dielectric medium, and at least a portion of these sparking electrodes is spaced-apart by dielectric substance layer and dielectric medium.

Please continue with reference to Fig. 1, time-pulse signal generator SE 112 meeting generation clock signals are with decision nmos pass transistor NT conducting (Turn-on) or close (Turn-off), thereby cause primary side circuit 110 to produce primary side current I1 signals.According to primary side current I1 signal, the secondary side W2 of transformer 130 can induce the secondary side current I2 signal of impulse form, makes the two ends of discharge lamp L can have a secondary side voltage signal and to drive discharge lamp L luminous.The drive circuit of known discharge lamp has following shortcoming:

1, the drive circuit of known discharge lamp drives with pulse signal, so the circuit complexity height.

2, the drive circuit of known discharge lamp is to drive discharge lamp with pulse signal, so each pulse signal must have enough energy just can light discharge lamp, and causes the cost of each part to improve.

3, pulse signal must have good waveform shaping, has therefore also improved the complexity of the drive circuit of known discharge lamp.

Summary of the invention

Therefore, purpose of the present invention is exactly that a kind of drive circuit of discharge lamp is being provided, and can make discharge lamp luminous with simple hardware structure.

A further object of the present invention provides a kind of driving method of discharge lamp, can make discharge lamp produce excellent energy efficient.

Purpose of the present invention is providing a kind of drive circuit of discharge lamp, and discharge lamp wherein has first capacitor.Drive circuit of the present invention mainly is made up of direct voltage source, second capacitor, transformer and switching circuit.Wherein first end of second capacitor couples direct voltage source, and its second side is then by switching circuit ground connection, and switching circuit then determines whether the second end ground connection with second capacitor according to a default clock signal.In addition, the two ends of first side of transformer couple first end and second end of second capacitor respectively, and the two ends of its second side then couple first end and second end of first capacitor respectively.

Under preferable situation, switching circuit has comprised nmos pass transistor.Wherein, first source/drain end couples second end of second capacitor, second source/drain end ground connection, and gate terminal then receives default clock signal.

In one embodiment of the invention, voltage supply circuit more comprises clock generating circuit, is used for producing default clock signal to switching circuit.

In addition, under preferable situation, default clock signal is a square-wave signal.And the frequency of this default clock signal start and stable in, have different numerical value to reach the purpose that moment starts.

From another viewpoint, the invention provides a kind of driving method of discharge lamp, its step is described below.At first, provide default clock signal and direct voltage, produce the primary side voltage signal according to presetting clock signal and direct voltage then.Then, the driving current signal of vibrating according to the primary side voltage signal, luminous to drive discharge lamp.

Under preferable situation, produce the step of driving current signal, more comprise following step.In the cycle of default clock signal forbidden energy, produce the primary side voltage signal.Induce corresponding secondary side voltage signal according to the primary side voltage signal, produce corresponding driving current signal according to the secondary side voltage signal then.

In addition, in the default clock signal activation cycle, the primary side voltage signal can be 0, thereby causes driving current signal by forbidden energy.

In sum, in the drive circuit of discharge lamp of the present invention, the primary side of transformer and second electric capacity, and the secondary side of transformer and first electric capacity are two LC resonant circuits, and therefore circuit structure of the present invention is very simple.In addition, driving current signal of the present invention is vibrated out by resonant circuit, and the form of non-pulse signal, therefore need not do complicated waveform shaping, and it is luminous just can to drive discharge lamp.

For above-mentioned and other purposes, feature and advantage of the present invention can be become apparent, a preferred embodiment cited below particularly, and cooperate appended graphicly, be described in detail below.

Description of drawings

Fig. 1 illustrates a kind of drive circuit figure of known discharge lamp.

Fig. 2 illustrates the drive circuit schematic diagram according to a kind of discharge lamp of a preferred embodiment of the present invention.

Fig. 3 illustrates the driving method flow chart according to a kind of discharge lamp of a preferred embodiment of the present invention.

Fig. 4 illustrates the signal timing diagram according to the drive circuit of a kind of discharge lamp of a preferred embodiment of the present invention.

110: primary side circuit 120: the secondary side circuit

130,230: transformer 112,216: clock pulse generator

210: voltage supply circuit 212: switching circuit

214:NMOS transistor 220: discharge lamp

S301, S303, S305: the driving method steps flow chart of discharge lamp

Embodiment

Fig. 2 illustrates the drive circuit schematic diagram according to a kind of discharge lamp of a preferred embodiment of the present invention.Please refer to Fig. 2, is to be used for driving the discharge lamp 220 with first capacitor C1 at drive circuit of the present invention.And in the present invention, first end of the second capacitor C2 couples first end of the primary side W1 of the direct voltage source Vsource that is used for supplying direct voltage and transformer 230.And second end of the second capacitor C2, then couple transformer 230 primary side W1 second end and by switching circuit 212 ground connection, wherein switching circuit 212 is to determine whether the second end conducting ground connection with the second capacitor C2 according to predetermined pulse signal CLK.In the present embodiment, default clock signal CLK can be a square-wave signal.In addition, the secondary side W2 of transformer 230 then is coupled to the two ends of the first capacitor C1 in the discharge lamp 220 respectively.

In the present embodiment, switching circuit 212 can comprise nmos pass transistor 214, its first source/drain end couples second end of the second capacitor C2, its second source/drain end ground connection, and its gate terminal then couples the clock pulse generator SE 216 that can be used for producing default clock signal CLK.Wherein, the frequency of default clock signal CLK has different numerical value and reaches the purpose that moment starts when starting and stablizing.

Fig. 3 illustrates the driving method flow chart according to a kind of discharge lamp of a preferred embodiment of the present invention.Please merge with reference to Fig. 3,, can provide default clock signal CLK to switching circuit 212 by clock pulse generator SE 216, and provide direct voltage by voltage source V source at first as described in the step S301.Then, voltage supply circuit 210 will be as described in the step S303, produces the primary side voltage signal according to default clock signal CLK and direct voltage.The secondary side W2 of transformer 230 will not be the driving current signal of pulse signal and vibrate, just step S305 according to the primary side voltage signal then.

Fig. 4 illustrates the signal timing diagram according to the drive circuit of a kind of discharge lamp of a preferred embodiment of the present invention.Please merge with reference to Fig. 4, the present invention in more detail, in the present embodiment, default clock signal CLK is a square-wave signal, when it is enabled (ON), switching circuit 212 conductings.On the contrary, if default clock signal CLK during by forbidden energy (OFF), 212 of switching circuits cut out.When default clock signal CLK is enabled (ON), primary side voltage signal Vp ground connection, so its voltage can be no better than 0, at this moment, the second capacitor C2 begins to charge gradually, and according to the formula of transformer:

$\frac{V1}{N1}=\frac{\mathrm{Vs}}{N2}$

Wherein, N1 and N2 represent the number of turn of the coil of the first side W1 of transformer 220 and the 2nd W2 respectively, and V1 then is the voltage of the first side W1 of transformer 220.The waveform that therefore can obtain secondary side voltage signal Vs as shown in Figure 4.In addition, when switching circuit 212 conductings, because the rate of change of secondary side voltage signal Vs is 0, and the following formula of foundation:

$I2=\frac{1}{L2}\∫\mathrm{Vsdt}---\left(1\right)$

Therefore wherein L2 is the inductance value of the second side W2 of transformer 220, can learn, driving current signal I2 can be no better than 0, so can't light discharge lamp 220.

In the present invention, the second side W2 of transformer 220 and the second capacitor C2 form a LC resonant circuit, therefore, as default clock signal CLK during by forbidden energy, can cause switching circuit 212 to be closed and present open-circuit condition, this moment, the second capacitor C2 began discharge, and make the second side W2 and the formed LC resonant circuit of the second capacitor C2 starting oscillation of transformer 220, and form as among Fig. 4, during default clock signal CLK was by the week of forbidden energy (OFF), primary side voltage signal Vp discharged and recharged waveform.Simultaneously, according to the formula of above-mentioned transformer, also can obtain the waveform of secondary side voltage signal Vs.At length, and the accurate position of secondary side voltage signal Vs rise to from minimum value Vs_min Vx during, because the speed of its increase is very fast, therefore according to (1) formula, the waveform of driving current signal I2 can be the ascending curve of a positive half cycle, and when the accurate arrival in the position of secondary side voltage signal Vs Vx, drive current also rises to maximum I2_max.

Please continue with reference to Fig. 2 and Fig. 4, after the waveform of secondary side voltage signal Vs passes through Vx, because the speed that increases begins to slow down, therefore the waveform of driving current signal I2 can begin to descend, arrive maximum Vs_max up to secondary side voltage signal Vs, this moment, driving current signal I2 can be no better than 0 according to (1) formula as can be known.And after the waveform of secondary side voltage signal Vs passes through maximum Vs_max, meeting decline rapidly, and because its slope becomes negative value, so the waveform of driving current signal I2 can increase towards negative half period.Similarly, after the waveform of secondary side voltage signal Vs was reduced to below the Vx, because the speed that reduces begins to slow down, so the waveform of driving current signal I2 began again to rise, and Vs reduces to minimum value Vs_min up to the secondary side voltage signal.

Default clock signal in the above embodiment can be the square-wave signal or the signal of other kinds, and the present invention is not limited.In addition, have the knack of the frequency that this skill person can adjust default clock signal, to reach best efficient combination.

In sum, the present invention comprises following advantage at least:

1. the present invention adopts direct voltage source to make initiatively power supply, so the hardware circuit framework is very simple.

2. in the present invention, the primary side of transformer and second capacitor can form a LC resonant circuit, and the secondary side of transformer and first capacitor can form another LC resonant circuit.Therefore the present invention can be vibrated driving current signal easily and do not needed complicated waveform shaping technology.

3. the present invention just can produce excellent energy efficient via the coupling of secondary side, first capacitor and the default clock signal of the primary side of transformer, second capacitor, transformer.

4. via the activation of adjusting default clock signal and the time of forbidden energy, just can make the present invention produce excellent energy efficient.

5. because of the present invention simple in structure, therefore cost of the present invention can reduce effectively.

Though the present invention discloses as above with preferred embodiment; right its is not in order to limit the present invention; anyly have the knack of this skill person; without departing from the spirit and scope of the present invention; when can doing a little change and retouching, so protection scope of the present invention is as the criterion when looking accompanying the claim person of defining.

Claims (9)

1, a kind of drive circuit of discharge lamp, wherein this discharge lamp has one first capacitor, it is characterized in that this drive circuit comprises:

One direct current voltage source;

One second capacitor, its first end couples this direct voltage source;

One transformer, the two ends of its first side couple first end and second end of this second capacitor respectively, and the two ends of its second side then couple first end and second end of this first capacitor respectively; And

One switching circuit couples ground connection with second end of this second capacitor, and with the second end ground connection of this second capacitor whether this switching circuit is to decide according to a default clock signal.

2, the drive circuit of discharge lamp according to claim 1, it is characterized in that wherein said switching circuit comprises a nmos pass transistor, its first source/drain end couples second end of this second capacitor, its second source/drain end ground connection, and its gate terminal then receives this default clock signal.

3, the drive circuit of discharge lamp according to claim 1 is characterized in that wherein said voltage supply circuit more comprises a clock generating circuit, should preset clock signal to this switching circuit in order to produce.

4, the drive circuit of discharge lamp according to claim 1 is characterized in that wherein said default clock signal is a square-wave signal.

5, the drive circuit of discharge lamp according to claim 1, the frequency that it is characterized in that wherein said default clock signal have different numerical value to reach the purpose that moment starts when starting and stablizing.

6, a kind of driving method of discharge lamp is characterized in that it comprises the following steps:

One default clock signal and a direct current voltage is provided;

According to presetting clock signal and this direct voltage, the mode of vibrating with LC produces a primary side voltage signal; And

The driving current signal of vibrating according to this primary side voltage signal is in order to drive this discharge lamp discharge.

7, the driving method of discharge lamp according to claim 6 is characterized in that wherein producing more comprising the following steps: the step of this driving current signal

In this default clock signal forbidden energy cycle, produce this primary side voltage signal;

Induce a corresponding secondary side voltage signal according to this primary side voltage signal; And

Produce corresponding this driving current signal according to this secondary side voltage signal.

8, the driving method of discharge lamp according to claim 6 is characterized in that wherein said default clock signal is a square-wave signal.

9, the drive circuit of discharge lamp according to claim 6, the frequency that it is characterized in that wherein said default clock signal have different numerical value to reach the purpose that moment starts when starting and stablizing.

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