CN101426324B - Fluorescent lamp starting process controlling circuit and control method therefor - Google Patents

Abstract

The present invention discloses a starting procedure control circuit of fluorescent lamp and a control method thereof. The circuit comprises a periphery capacitor, switches of S0 and S1 connected with the periphery capacitor, a plurality of switch group of group 0 to group N which are formed through the series connection of two switches. Group 0 comprises switches of S00 and S10,..., and group N comprise switches of S0N and S1N. Two switches in each group respectively control two current sources with same magnitude, and the binding point between the two switches is connected the periphery capacitor. The method comprises high frequency preheating and frequency sweep ignition when only the switch S0 is conducted; and low frequency normal operation when only the switch S0 is switched off. In frequency sweep ignition, switches of S0 and S1 are all switched off, switches of S00 to S0N in group 0 to group N are all conducted, switches of S10 to S1N in group 0 to group N are all switched off, then one or a plurality of switches selected from S10 to S1N are conducted in sequence, and the rest switches are switched off. The invention adopts a digitized method for controlling the processes of high frequency preheating, frequency sweep ignition and low frequency operation required for actuating the fluorescent lamp.

Description

A kind of fluorescent lamp starting process control circuit and control method thereof

Technical field

The present invention relates to lighting field, relate in particular to a kind of control Driver Circuit and control method thereof that is used for the electric ballast of lighting circuit fluorescent lamp.

Technical background

Realize that at present three required states of fluorescent lamp starting are: radio-frequency preheating, frequency sweep igniting (high frequency → low frequency), low frequency operation.In order to realize energy-efficient lighting system; Electric ballast need convert power frequency component into high-frequency square-wave signal with the driving fluorescent lamp load circuit usually; And because the startup of fluorescent lamp need be passed through preheating → igniting → operate as normal three phases, so electric ballast need provide the square-wave signal of high frequency → frequency sweep → low frequency.

See also Fig. 1; Realization schematic diagram for the voltage controlled oscillator of prior art; Wherein Vc is control voltage, and Rt is external concussion resistance, and earlier following transistor Mn1 through amplifier and source electrode, will to control voltage transitions be Control current Vc/Rt; Be separately converted to current source I1, the I2 to external capacitor Ct charge and discharge through the current mirror copy again, its estimation expression formula difference is formula as follows.

$\mathrm{<figure-callout\; id="1"\; label="I"\; filenames="H2008102041195E00021.png"\; state="\{\{state\}\}">I</figure-callout>}1=\frac{{(W/L)}_{p3}}{{(W/L)}_{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="H2008102041195E00021.png"\; state="\{\{state\}\}">p</figure-callout>}1}}\&CenterDot;\frac{V_c}{R_t}$

$\mathrm{<figure-callout\; id="2"\; label="I"\; filenames="H2008102041195E00021.png"\; state="\{\{state\}\}">I</figure-callout>}2=\frac{{(W/L)}_{p2}}{{(W/L)}_{\mathrm{<figure-callout\; id="1"\; label="p"\; filenames="H2008102041195E00021.png"\; state="\{\{state\}\}">p</figure-callout>}1}}\&CenterDot;\frac{{(W/L)}_{n3}}{{(W/L)}_{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="H2008102041195E00021.png"\; state="\{\{state\}\}">n</figure-callout>}2}}\&CenterDot;\frac{V_c}{R_t}$

In the formula

W/L---transistorized breadth length ratio

VC---voltage controlled oscillator control voltage

Rt---external concussion resistance

V1, V2 are respectively the last lower threshold voltage of comparator among the figure, and the voltage on Ct surpasses V1, and comparator toggles, and the logical circuit output high level of control back are opened the Mn4 pipe, turn-off the Mp4 pipe, capacitor discharge; Voltage on Ct is less than V2, and comparator toggles, and the logical circuit output low level of control back are opened the Mp4 pipe, turn-off the Mn4 pipe, the electric capacity charging.Therefore, at output node Vout place, we can obtain a standard square-wave signal, below our will derive frequency expression formula of this square-wave signal.

Known

Q＝CU＝It

So, the charge and discharge time t of each clock cycle electric capacity _r, t _fBe respectively

$t_r=\frac{\mathrm{CU}}{I}=\frac{C_t(V1-V2)}{I1}$

$t_f=\frac{\mathrm{CU}}{I}=\frac{C_t(V1-V2)}{I2}$

Clock cycle then

$T=t_r+t_f=\frac{C_t(V1-V2)}{\mathrm{<figure-callout\; id="1"\; label="I"\; filenames="H2008102041195E00021.png"\; state="\{\{state\}\}">I</figure-callout>}1}+\frac{C_t(V1-V2)}{I2}$

Select the size of current mirror transistor to make $\mathrm{<figure-callout\; id="1"\; label="I"\; filenames="H2008102041195E00021.png"\; state="\{\{state\}\}">I</figure-callout>}1=I2=m\frac{V_c}{R_t}$ , output signal frequency is expressed and is shown as follows

$f=\frac{1}{T}=\frac{1}{t_r+t_f}=\frac{m{V}_c}{2R_t\&CenterDot;C_t\&CenterDot;(V1-V2)}$

Can find out that from following formula signal output frequency is directly proportional with control voltage.

Fluorescent lamp starting will pass through radio-frequency preheating, frequency sweep igniting, low frequency operate as normal three phases usually.Common implementation method is earlier through preheating electric capacity (is received long influence warm-up time; This electric capacity is bigger) charge and discharge produce control voltage of voltage-controlled oscillator; Because the oscillator output frequency is directly proportional with the control voltage swing, so finally control the variation of voltage and signal frequency shown in figure two.VC representes control voltage of voltage-controlled oscillator among the figure, and f representes the oscillator output frequency.

In the prior art; Use the voltage controlled oscillator clocking; The function that realizes the frequency sweep igniting must produce a scanning voltage from high to low earlier, and this voltage usually will be through the filling of very big electric capacity, put a little and produce, and has increased the pin or the increase area of chip of chip.

Summary of the invention

The objective of the invention is to overcome the defective of prior art, and a kind of fluorescent lamp starting process control circuit and control method thereof are provided, it adopts method for digitizing control to realize the required radio-frequency preheating of fluorescent lamp starting, frequency sweep igniting and low frequency operation process.

The technical scheme that realizes above-mentioned purpose is:

A kind of fluorescent lamp starting process control circuit of one of the present invention comprises an external capacitor Ct, wherein, comprises some switches set that are in series by two switches, and for organizing 0 to group N, group 0 comprises switch S ₀₀And switch S ₁₀, group 1 comprises switch S ₀₁And switch S ₁₁..., group N comprises switch S _0NAnd S _1N, two switches of every group are controlled two identical current sources of size respectively so that open simultaneously and can cancel each other, and the node between two switches of every group all links to each other to charge with described external capacitor Ct, also comprises the switch S that links to each other with external capacitor Ct ₀And S ₁, wherein:

Two switch S of described group 0 ₀₀And switch S ₁₀The current source of control is I ₀, two switch S of group 1 ₀₁And switch S ₁₁The current source of control is 2 _I0..., two switch S of group N _0NAnd S _1NThe current source of control is 2 ^NI ₀

Described switch S ₀The current source of control is 2 ^N+1I ₀

Described switch S ₁The current source of control is 2 ^NI ₀

Wherein, N is the integer more than or equal to 0.

A kind of control method based on above-mentioned fluorescent lamp starting process control circuit of two of the present invention comprises radio-frequency preheating, frequency sweep igniting and the low frequency operate as normal of fluorescent lamp starting process, wherein,

During radio-frequency preheating, switch S ₀Conducting, rest switch all turn-offs, and giving the electric current of capacitor C t charging this moment is 2 ^N+1I ₀

During the frequency sweep igniting, in switch S ₀And S ₁Turn-off, group 0 is to the switch S of organizing among the N ₀₀, S ₀₁..., S _0NAll under the condition of conducting, at first, group 0 is to the switch S of organizing among the N ₁₀, S ₁₁..., S _1NAll turn-off, open switch S then successively ₁₀, S ₁₁..., S _1NIn one or certain several, all the other shutoffs;

During the low frequency operate as normal, group 0 is to the whole conductings of organizing among the N of switch, switch S ₀Turn-off switch S ₁Conducting, giving the electric current of capacitor C t charging this moment is 2 ^NI ₀, wherein N is the integer more than or equal to 0.

The control method of above-mentioned fluorescent lamp starting process control circuit wherein, when frequency sweep is lighted a fire, is opened switch S each time ₁₀, S ₁₁..., S _1NIn one or certain several, according to switch S ₁₀, S ₁₁..., S _1NIn the order that increases progressively successively of the size in the total current source controlled open.

The invention has the beneficial effects as follows: the present invention adopts method for digitizing to control and realizes the course of work that fluorescent lamp starting is required, changed original implementation, gives capacitor C _tA charging current source that successively decreases one by one is provided; And the frequency of oscillator signal is directly proportional with the size of this charging current on the electric capacity; So the final output signal frequency that produces also successively decreases one by one, realized that promptly radio-frequency preheating, the frequency sweep to fluorescent lamp starting process lighted a fire, the control of low frequency operate as normal.

Description of drawings

Fig. 1 is the realization schematic diagram of the voltage controlled oscillator of prior art;

Fig. 2 is the graph of a relation that control voltage of the prior art and signal frequency change;

Fig. 3 is the implementation structure figure of one of the present invention's fluorescent lamp starting process control circuit;

Fig. 4 is the present invention's two frequency or a charging current size and time relation figure.

Embodiment

Below in conjunction with accompanying drawing the present invention is described further.

See also Fig. 3, a kind of fluorescent lamp starting process control circuit of one of the present invention has been shown among the figure, comprise an external capacitor Ct, also comprise some switches set that are in series by two switches, for organizing 0 to group N, group 0 comprises switch S ₀₀And switch S ₁₀, group 1 comprises switch S ₀₁And switch S ₁₁..., group N comprises switch S _0NAnd S _1N, two switches of every group are controlled two identical current sources of size respectively so that open simultaneously and can cancel each other, and the node between two switches of every group all links to each other to charge with described external capacitor Ct, also comprises the switch S that links to each other with external capacitor Ct ₀And S ₁, wherein:

Two switch S of group 0 ₀₀And switch S ₁₀The current source of control is I ₀, two switch S of group 1 ₀₁And switch S ₁₁The current source of control is 2I ₀..., two switch S of group N _0NAnd S _1NThe current source of control is 2 ^NI ₀

Switch S ₀The current source of control is 2 ^N+1I ₀

Switch S ₁The current source of control is 2 ^NI ₀

Wherein, N is the integer more than or equal to 0.

The control method of a kind of fluorescent lamp starting process control circuit based on claim 1 of two of the present invention comprises radio-frequency preheating, frequency sweep igniting and the low frequency operate as normal of fluorescent lamp starting process, wherein,

During radio-frequency preheating, switch S ₀Conducting, rest switch all turn-offs, and giving the electric current of capacitor C t charging this moment is 2 ^N+1I ₀

During the frequency sweep igniting, in switch S ₀And S ₁Turn-off, group 0 is to the switch S of organizing among the N ₀₀, S ₀₁..., S _0NAll under the condition of conducting, at first, group 0 is to the switch S of organizing among the N ₁₀, S ₁₁..., S _1NAll turn-off, open switch S successively according to certain order and combination then ₁₀, S ₁₁..., S _1NIn one or certain several, all the other shutoffs;

When frequency sweep is lighted a fire, open switch S each time ₁₀, S ₁₁..., S _1NIn one or certain several (according to switch S ₁₀, S ₁₁..., S _1NIn the order that increases progressively successively of the size in the total current source controlled open), for example: S for the first time ₁₀, S ₁₁..., S _1NAll turn-off; For the second time, open S ₁₀, with the current source of top counteracting be I ₀For the third time, open S ₁₁, with the current source of top counteracting be 2I ₀The 4th time, open S ₁₀And S ₁₁, with the current source of top counteracting be I ₀+ 2I ₀=3I ₀, the 5th time, open S ₁₂, with the current source of top counteracting be 4I ₀The 6th time, open S ₁₀And S ₁₂, with the current source of top counteracting be I ₀+ 4I ₀=5I ₀The 7th time, open S ₁₁And S ₁₂, with the current source of top counteracting be 2I ₀+ 4I ₀=6I ₀... the 2nd ^N-1 time, open S ₁₁+ ...+S _1N-1, with the current source of top counteracting be 2I ₀+ 4I ₀+ ...+2 ^N-1I ₀=(2 ^N-2) I ₀

That is, the size in the total current source controlled of the switch of opening each time increases progressively I successively ₀, 2I ₀, 3I ₀, 4I ₀, 5I ₀..., (2 ^N-2) I ₀

Embodiment is following:

The 1st time, switch S ₀, S ₁Turn-off switch S _Oo, S _O1... S _ONAll conductings; Switch S _1o, S ₁₁... S _1NTurn-off, be to this moment the electric current of capacitor C t charging:

I ₀+2I ₀+......+2 ^NI ₀＝(2 ^N+1-1)I ₀；

The 2nd time, switch S ₀, S ₁Turn-off switch S _Oo, S _O1... S _ONAnd S _1oConducting, rest switch turn-offs, because switch S _OoAnd switch S _1oThe big or small identical of current source of corresponding control (is I ₀), cancel out each other, so become for the electric current of capacitor C t charging:

2I ₀+......+2 ^NI ₀＝(2 ^N+1-2)I ₀；

The 3rd time, switch S ₀, S ₁Turn-off switch S _Oo, S _O1... S _ONAnd S ₁₁Conducting, rest switch turn-offs, because switch S ₀₁And S ₁₁The big or small identical of current source of corresponding control (is 2I ₀), cancel out each other, so give capacitor C _tThe electric current of charging becomes:

I ₀+4I ₀......+2 ^NI ₀＝(2 ^N+1-3)I ₀；

The 4th, switch S ₀, S ₁Turn-off switch S _Oo1, S _O1... S _ONAnd S _1o, S ₁₁Conducting, rest switch turn-offs, because switch S _Oo, S ₀₁And S _1o, S ₁₁The big or small identical of current source of corresponding control (is I ₀+ 2I ₀), cancel out each other, so give capacitor C _tThe electric current of charging becomes:

4I ₀+8I ₀......+2 ^NI ₀＝(2 ^N+1-4)I ₀；

……

The 2nd ^N-1 time, switch S ₀, S ₁Turn-off S _Oo, S _O1... S _ONAnd S ₁₁, S ₁₂... S _1N-1Conducting, rest switch turn-offs, S ₁₁, S ₁₂... S _1N-1And S ₀₁, S ₀₂... S _ON-1The big or small identical of current source of corresponding control (is (2 ^N-2) I ₀), cancel out each other, so give capacitor C _tThe electric current of charging becomes:

I ₀+2 ^NI ₀＝(2 ^N+1)I ₀；

During the low frequency operate as normal, group 0 is to the whole conductings of organizing among the N of switch, switch S ₀Turn-off switch S ₁Conducting, current source is offset capacitor C t is not exerted an influence up and down, and giving the electric current of capacitor C t charging this moment is 2 ^NI ₀, wherein N is the integer more than or equal to 0.

A charging current source that successively decreases one by one is provided among the present invention capacitor C t; And the frequency of oscillator signal is directly proportional with the size of this charging current on the electric capacity; So the final output signal frequency that produces also successively decreases one by one, please refer to Fig. 4, frequency of the present invention or charging current size and time relation figure; F representes to state place's signal frequency among the figure; I representes to shake the charging current source of capacitor C t, this shows that the present invention has realized radio-frequency preheating, the frequency sweep igniting to fluorescent lamp starting process, the control of low frequency operate as normal, has adopted digitized mode to overcome present shortcoming.

Need to prove: above only unrestricted technical scheme of the present invention in order to explanation; Although the present invention is specified with reference to the foregoing description; Those of ordinary skill in the art is to be understood that: still can make amendment or be equal to replacement the present invention; And replace any modification or the part that do not break away from the spirit and scope of the present invention, and it all should be encompassed in the middle of the claim scope of the present invention.

Claims (2)

1. a fluorescent lamp starting process control circuit comprises an external capacitor Ct, it is characterized in that, comprises some switches set that are in series by two switches, and for organizing 0 to group N, group 0 comprises switch S ₀₀And switch S ₁₀, group 1 comprises switch S ₀₁And switch S ₁₁..., group N comprises switch S _0NAnd S _1N, two switches of every group are controlled two identical current sources of size respectively so that open simultaneously and can cancel each other, and the node between two switches of every group all links to each other to charge with described external capacitor Ct, also comprises the switch S that links to each other with external capacitor Ct ₀And S ₁, wherein:

Two switch S of described group 0 ₀₀And switch S ₁₀The current source of control is I ₀, two switch S of group 1 ₀₁And switch S ₁₁The current source of control is 2I ₀..., two switch S of group N _0NAnd S _1NThe current source of control is 2 ^NI ₀

Described switch S ₀The current source of control is 2 ^N+1I ₀

Described switch S ₁The current source of control is 2 ^NI ₀

Wherein, N is the integer more than or equal to 0.

2. control method based on the fluorescent lamp starting process control circuit of claim 1 comprises it is characterized in that radio-frequency preheating, frequency sweep igniting and the low frequency operate as normal of fluorescent lamp starting process,

During radio-frequency preheating, switch S ₀Conducting, rest switch all turn-offs, and giving the electric current of capacitor C t charging this moment is 2 ^N+1I ₀

During the frequency sweep igniting, in switch S ₀And S ₁Turn-off, group 0 is to the switch S of organizing among the N ₀₀, S ₀₁..., S _0NAll under the condition of conducting, at first, group 0 is to the switch S of organizing among the N ₁₀, S ₁₁..., S _1NAll turn-off, open switch S then successively ₁₀, S ₁₁..., S _1NIn one or certain several, all the other shutoffs;

When frequency sweep is lighted a fire, open switch S each time ₁₀, S ₁₁..., S _1NIn one or certain several, according to switch S ₁₀, S ₁₁..., S _1NIn the order that increases progressively successively of the size in the total current source controlled open;

During the low frequency operate as normal, group 0 is to the whole conductings of organizing among the N of switch, switch S ₀Turn-off switch S ₁Conducting, giving the electric current of capacitor C t charging this moment is 2 ^NI ₀, wherein N is the integer more than or equal to 0.

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