CN201051193Y

CN201051193Y - Power circuit of backlight display system

Info

Publication number: CN201051193Y
Application number: CNU2006200154119U
Authority: CN
Inventors: 谭继荣
Original assignee: SHENZHEN SAIQI INNOVATION TECHNOLOGY Co Ltd
Current assignee: SHENZHEN SAIQI INNOVATION TECHNOLOGY Co Ltd
Priority date: 2006-10-25
Filing date: 2006-10-25
Publication date: 2008-04-23
Anticipated expiration: 2016-10-25

Abstract

The utility model discloses a power circuit for a backlighting display system. The utility model can ensure the normal starting and current balance of the working of a plurality of luminous bodies of cold cathode fluorescent lamps (CCFL) or external electrode fluorescent lamp (EEFL) in series connection and in parallel connection. The employed technical scheme of the utility model is that a backlighting power supply is employed as a luminous circuit to provide a high-voltage power supply, the luminous circuit includes a plurality of the luminous bodies and a plurality of mutual inductors, each luminous circuit is inserted in the backlighting power supply after being in series connection with a primary coil of the mutual inductor corresponding to the luminous body, forming a return circuit, each luminous body is in parallel connection with the circuit forming by the primary coils of the mutual inductors, an in-phase end of the secondary coil of the first mutual inductor is connected with an out-phase end of the secondary coil of the adjacent mutual inductor, and so on, an in-phase end of the secondary coil of the mutual inductor is connected with an out-phase end of the secondary coil of the first mutual inductor, and all the secondary coils of the mutual inductors are in series connection. Because each mutual inductor has the same parameters, the secondary coils of each mutual inductor work in serious connection, and primary coils of the mutual inductors have the same currents, thereby each luminous body has the same current, solving the current balance problem of a plurality of luminous bodies which are used in parallel connection.

Description

The power circuit of backlight display system

Technical field

The utility model relates to a kind of power circuit of backlight display system, particularly relates to the backlight circuit that a kind of CCFL of utilization or EEFL make backlight.

Background technology

In the prior art, in the backlight circuit of LCDs (LCD) product, use cold-cathode fluorescence lamp (CCFL) or external electrode fluorescent lamp (EEFL) as its backlight.Because CCFL and EEFL be the voltage height when starting, and voltage is low during operate as normal, trigger voltage requires more than the 1000V usually for CCFL, and the voltage of operate as normal has only 300V usually between the 800V, if it is a plurality of CCFL are directly in parallel, when adding the above voltage starting of 1000V, because between each CCFL, performance difference is arranged, often cause that to have only a CCFL to start luminous, after this CCFL starts, impressed voltage drops to below the 800V, other CCFL can not start, when using EEFL as luminophor, just the trigger voltage that requires is higher, and the voltage of operate as normal improves relatively, therefore need increase electric capacity (as Fig. 1) when in the prior art CCFL and EEFL being carried out parallel running or transformer (as Fig. 2) circuit could start all CCFL in parallel or EEFL, the circuit of luminophor tandem working does not also appear in prior art.

Fig. 1 utilizes CCFL for prior art and does the circuit diagram of LCD back light, in this circuit, the electric capacity of connecting between each CCFL and the backlight electric power, because capacitance partial pressure effect, after CCFL starts, during the CCFL operate as normal, there is voltage at the capacitor two ends, the operating voltage of CCFL when the voltage of electric capacity adds operate as normal, other CCFL is started, but, flow through the current imbalance of each CCFL, when current error is excessive because each CCFL performance is variant, the electric current that some of them CCFL flows through is too big, make the life-span of CCFL descend, and the electric current of other CCFL is too small, CCFL does not reach design brightness.

Fig. 2 utilizes CCFL for prior art and makees the another kind of structural circuit synoptic diagram of LCD back light, on the basis of Fig. 1, increase a transformer in each CCFL circuit, utilize transformer to boost for each CCFL fluorescent tube, though this technical scheme solved CCFL directly parallel connection light, technical matterss such as working current imbalance and since each transformer must with the supporting use of corresponding CCFL, circuit is adjusted difficulty, poor compatibility when changing CCFL, need be readjusted circuit.This technical scheme has cost height, working service inconvenience, and along with the increase of CCFL quantity, circuit impedance increases, and temperature raises and causes the increase of life of product decline and power consumption.

Summary of the invention

In order to solve the above-mentioned technical matters that luminophor such as CCFL or EEFL parallel running brings in the prior art, reduce product and use and manufacturing cost, the utility model designs a kind of power circuit of novel backlight display system.

The utility model is that the technical scheme that its goal of the invention of realization is adopted is: the power circuit of backlight display system, comprise backlight electric power, illuminating circuit, backlight electric power provides high-voltage power supply for illuminating circuit, the mutual inductor that comprises a plurality of luminophors and luminophor quantity correspondence in the illuminating circuit, each luminophor one end is connected with the primary coil of the mutual inductor of corresponding setting, the other end of the other end of luminophor and the primary coil of mutual inductor links to each other with the two poles of the earth of backlight electric power respectively, chopped-off head mutual inductor secondary coil one end is connected with the other end of final stage mutual inductor secondary coil, and the other end of chopped-off head mutual inductor secondary coil is connected in series through the other end of intergrade mutual inductor secondary coil and level mutual inductor secondary coil not out-phase successively.

Further improve as the utility model,, can between the other end of mutual inductor and backlight electric power transformer, serially add a luminophor, finish the luminophor tandem working as long as it is enough high that the transformer parameter of backlight electric power is adjusted the suitable output voltage that makes.In addition in illuminating circuit between the adjacent mutual inductor secondary coil through two resistance in series ground connection, between two resistance in seriess, stretch out a detection head and can detect circuit easily.

The beneficial effects of the utility model are, since used mutual inductor, the primary coil of mutual inductor and luminophor series connection, and each secondary coil is connected mutually, circuit is very simple, debugging easily, detection, electric energy and magnetic energy in each mutual inductor coil are changed mutually, and resistance is little, reduce the heating of electric elements, reduce power consumption, improve product serviceable life, a kind of circuit that improves simultaneously of the present utility model has solved the problem that luminophor for a long time can not tandem working.

Description of drawings

Fig. 1: CCFL circuit theory diagrams in the prior art.

Fig. 2: CCFL circuit theory diagrams in the prior art.

Fig. 3: the utility model embodiment 1 circuit theory diagrams.

Fig. 4: the utility model embodiment 2 circuit theory diagrams.

Fig. 5: the utility model embodiment 3 circuit theory diagrams.

Fig. 6: the utility model current detection circuit schematic diagram.

Among the figure: 1,2 primary coils, 3,4 secondary coils, 5 power-supply controller of electric, 6 transformers, T mutual inductor, 81,82,83,84,85,86 luminophors.

Embodiment

This is described in detail the utility model embodiment with reference to 3 couples in figure.The power circuit of backlight display system comprises backlight electric power, illuminating circuit, backlight electric power provides high-voltage power supply for illuminating circuit, backlight electric power is made up of driving circuit 5 and transformer 6, backlight electric power is transformed into ac high-voltage with dc low-voltage, comprise a plurality of luminophors 81 in the illuminating circuit, 82,83 and the mutual inductor T1 corresponding with luminophor quantity, T2, T3, each

luminophor

81,82, the mutual inductor T1 of 83 1 ends and corresponding setting, T2, the primary coil (1 of T3,2) series connection,

luminophor

81,82,83 the other end and the primary coil of mutual inductor (1,2) the other end links to each other with the two poles of the earth of backlight electric power respectively, chopped-off head mutual inductor T1 secondary coil (3,4) a end and (3 of level mutual inductor secondary coil not, 4) the out-phase end connects, chopped-off head mutual inductor T secondary coil (3,4) the other end is through intergrade mutual inductor secondary coil (3,4) with level mutual inductor secondary coil (3 not, 4) other end out-phase successively is connected in series.

Start moment at the CCFL fluorescent tube, because the parameter of every tubes can not be absolute the same, so just having a tubes lights at first, after this tubes is lighted, just the voltage at backlight electric power transformer 6 two ends has been dragged down, at this moment other fluorescent tube just temporarily can not be lighted, and does not also just temporarily have electric current to flow through.After this tubes is lighted, just have the primary coil (1 that an electric current flows through the mutual inductor T of series connection with it, 2), because primary coil (1,2) there is electric current to tide over, according to the mutual inductor principle, its secondary coil (3,4) also there is induction current to tide on, because the secondary coil (3 of all mutual inductor T, 4) connect, so just have the secondary coil (3 that an electric current flows through the mutual inductor of connecting with the fluorescent tube that other is not lighted, 4), again because the mutual inductance effect of mutual inductor, will be at the primary coil (1 of these mutual inductors, 2) produce a voltage, the voltage superposition at this voltage and transformer 6 two ends this moment, the lamp tube ends of not lighting like this, to reach and light the required voltage of fluorescent tube, thereby normally light fluorescent tube, so, all light other fluorescent tube, finally reach parallel running moment normally to light the purpose of whole CCFL fluorescent tubes.

Because the parameter of each mutual inductor T is identical, and the secondary coil of each mutual inductor (3,4) tandem working, the electric current that guarantees each mutual inductor secondary coil (3,4) like this is identical, according to the mutual inductance principle, then the electric current of the primary coil of mutual inductor (1,2) is identical, the electric current of every like this each luminophor is identical, has solved the current balance type problem when a plurality of luminophors are in parallel to be used.

Luminophor of the present utility model can be cold-cathode fluorescence lamp (CCFL) or external electrode fluorescent lamp (EEFL).

Fig. 4 is the circuit theory diagrams of the utility model embodiment 2, at this moment backlight electric power is selected the higher transformer 6 of output voltage, between primary winding of mutual inductor (1,2) and power electrode, increase a luminophor, it can make two luminophors, 81,84 series connection backs start and the energy operate as normal, and this structure is specially adapted to large-sized LCDs and uses.

Fig. 5 is the circuit theory diagrams of embodiment 3 of the present utility model, use the circuit of the opposite transformer 6 driven for emitting lights body series and parallel work of two phase places, the secondary coil series connection output of two transformer T, increase the driving voltage of power supply, this is very important when using external electrode fluorescent lamp EEFL to need high starting voltage and high working voltage for luminophor, respectively connect a

luminophor

81,84 at the two ends of mutual inductor like this and not only can normally all start, but while holding current balance.

The utility model is because the secondary coil (3 of mutual inductor, 4) all adopt series connection, and parameter each other is the same, electric current also is the same, so when whole luminophor operate as normal, the junction current potential of each mutual inductor secondary coil is all the same, between the junction of each adjacent mutual inductor secondary coil and ground, connect two resistance, between two resistance, connect a detection head, when all luminophor operate as normal, the current potential of detection head is an electronegative potential, when damaging if any a luminophor, then the circuit at its place is in open-circuit condition, then the detection head between the resistance just is high level, the part that so just can detect open circuit as shown in Figure 6, thereby the fault location point.

Claims

1. the power circuit of a backlight display system, comprise backlight electric power, illuminating circuit, backlight electric power provides high-voltage power supply for illuminating circuit, it is characterized in that: the mutual inductor that comprises a plurality of luminophors and luminophor quantity correspondence in the illuminating circuit, the primary coil (1 of each luminophor one end and the mutual inductor of corresponding setting, 2) series connection, (1 of the other end of luminophor and the primary coil of mutual inductor, 2) other end links to each other with the two poles of the earth of backlight electric power respectively, chopped-off head mutual inductor T1 secondary coil (3,4) end and final stage mutual inductor T3 secondary coil (3,4) the other end connects, chopped-off head mutual inductor T1 secondary coil (3,4) the other end is through intergrade mutual inductor T2 secondary coil (3,4) with level mutual inductor T3 secondary coil (3 not, 4) other end out-phase successively is connected in series.

2. the power circuit of a kind of backlight display system according to claim 1 is characterized in that: in the described illuminating circuit, also be in series with luminophor between each primary winding of mutual inductor (1,2) other end and backlight electric power.

3. the power circuit of a kind of backlight display system according to claim 1 and 2, it is characterized in that: described luminophor is cold-cathode fluorescence lamp CCFL or external electrode fluorescent lamp EEFL.

4. the power circuit of a kind of backlight display system according to claim 1 is characterized in that: in the described illuminating circuit between the adjacent mutual inductor secondary coil (3,4) through two resistance in series ground connection.